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Ammonia removal and recovery using heated struvite as an adsorbent Novotny, Chad 2011

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AMMONIA REMOVAL AND RECOVERY USING HEATED STRUVITE AS AN ADSORBENT  by Chad Novotny B.Sc., Simon Fraser University, 2008  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF APPLIED SCIENCE  in  The Faculty of Graduate Studies  (Civil Engineering)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  February 2011  © Chad Novotny, 2011  Abstract The removal and recovery of aqueous ammonia from BNR plant centrate or supernatant is an important research area. Stringent ammonia discharge requirements must be met to avoid fish toxicity in the receiving waters. Completely removing ammonia from the process reduces the load recycled back to the head of the plant and minimizes operational problems associated with high return loads. The controlled recovery of phosphate and ammonia into struvite with a dedicated fluidized bed crystallizer has led to the production of commercially valuable struvite pellets for the fertilizer industry. However, excess ammonia remains after struvite crystallization.  The purpose of this research was to initiate the development of a nitrogen removal technology. This was achieved using the isothermal decomposition of struvite to remove ammonia. The decomposed pellets were subsequently placed into an ammonium solution for removal of excess aqueous ammonium. Struvite was shown to decompose into a mixture of magnesium phosphates and struvite. Satisfactory decomposition was achieved with a minimum of 100°C for 30 minutes. Ammonium removal reached up to 99% for a solution pH 8. Effective ammonia-N removal required a minimum reaction duration of between 15-30 minutes with a 66.7g/L dose.  Struvite heated at higher temperatures worked as a better substrate to remove aqueous ammonia-N. Molar ratio comparisons show that the ammonia removed from solution is likely incorporated into newly formed fine struvite, rather than being incorporated into the heated struvite. This provides evidence in favour of a dissolution-reformation ii  mechanism, whereby heated struvite acts a source of magnesium and phosphate. Heated struvite is more soluble than unheated struvite, because water of hydration and ammonia are removed from the pellet. Mass balances were reasonable but were complicated by natural adsorption of atmospheric water onto heated pellets.  The economic viability of this technology may be unfavourable. A trade off exists between high ammonium removal and dissolution of pellets, which are worth up to $3000 per tonne in the United States. The total daily cost to remove nitrogen using this technology is estimated to be about 15 times greater than using side stream nitrification.  iii  Table of contents Abstract ............................................................................................................................... ii Table of contents ................................................................................................................ iv List of tables ..................................................................................................................... viii List of figures ..................................................................................................................... xi Acknowledgements ........................................................................................................ xviii 1 Introduction ...................................................................................................................... 1 2 Research objectives .......................................................................................................... 5 3 Literature review .............................................................................................................. 6 3.1 Solution equilibria..................................................................................................... 6 3.2 Struvite chemistry ..................................................................................................... 6 3.3 Struvite (MAP) process............................................................................................. 7 3.4 Ammonia as an energy source .................................................................................. 8 3.5 Struvite thermal decomposition ................................................................................ 8 3.5.1 Thermal mass loss .............................................................................................. 9 3.5.2 Thermal gravimetric analysis (TGA) ................................................................. 9 3.5.3 Thermo-gas (TG) titrimetry ............................................................................. 10 3.5.4 Evolved gas analysis (EGA) ............................................................................ 12 3.5.5 Inductively coupled plasma (ICP) spectroscopy.............................................. 13 3.5.6 Fourier transform infrared spectroscopy (FT-IR) ............................................ 14 3.5.7 Ammonium content using distillation and titration ......................................... 14 3.5.8 31P Magic angle spinning nuclear magnetic resonance (31P MAS NMR) ....... 15 3.5.9 Heating in acid and alkali solutions ................................................................. 15 3.6 Aqueous recovery of ammonium ............................................................................ 16 3.6.1 Struvite and newberyite solubility ................................................................... 16 3.6.2 Solution-mediated reformation mechanism ..................................................... 17 3.6.3 Dissolution reformation mechanism ................................................................ 17 3.6.4 Complete acid dissolution reformation mechanism ......................................... 18 3.6.5 Gaseous adsorption .......................................................................................... 18 4 Materials and methods ................................................................................................... 19 4.1 Reactor design ......................................................................................................... 19 4.2 Thermally decomposing struvite............................................................................. 20 4.3 Feed solution characteristics ................................................................................... 20 iv  4.4 Aqueous uptake experiments .................................................................................. 21 4.5 Pellet drying and collecting .................................................................................... 22 4.6 Struvite product sample preparation ....................................................................... 23 4.7 Aqueous analytical methods ................................................................................... 24 4.7.1 Magnesium ....................................................................................................... 24 4.7.2 Ammonia-N ..................................................................................................... 24 4.7.3 Orthophosphate ................................................................................................ 24 4.8 Molar ratios ............................................................................................................. 24 4.9 Mass balance ........................................................................................................... 25 4.10 Heated pellet dissolution in DI water.................................................................... 25 4.11 Elemental analysis (EA) ....................................................................................... 25 4.12 Impurities – Total inorganic carbon and elemental analysis ................................ 26 4.13 Scanning electron microscopy (SEM) analysis .................................................... 26 5 Results and discussion ................................................................................................... 27 5.1 Thermal decomposition .......................................................................................... 27 5.1.1 Mass loss curves .............................................................................................. 27 5.1.2 Mass gain versus time ...................................................................................... 28 5.1.3 Vacuum desiccation ......................................................................................... 30 5.2 Elemental analysis .................................................................................................. 31 5.2.1 Ammonia content ............................................................................................. 31 5.2.2 Water content ................................................................................................... 33 5.2.3 Possible chemical identity................................................................................ 34 5.2.4 Environment effects on ammonia and water content ....................................... 35 5.2.5 Comparing heated pellets to uptake pellets ..................................................... 36 5.3 Wet-chemical analysis – Molar ratios..................................................................... 38 5.3.1 N:P ratio ........................................................................................................... 39 5.3.2 N:Mg ratio ........................................................................................................ 40 5.3.3 Mg:P ratio ........................................................................................................ 41 5.4 Bulk sample heating ................................................................................................ 41 5.4.1 Percent mass remaining ................................................................................... 42 5.4.2 Comparison of crushed and pelletized struvite from Lulu Island WWTP and Edmonton Alberta Gold Bar WWTP ........................................................................ 42 5.4.3 Time to achieve chemical transformation ........................................................ 44 5.5 Uptake stage one: June 2009-October 2009 ........................................................... 46 5.5.1 Ammonium profile........................................................................................... 46 v  5.5.1.1 Total ammonia concentration versus time at pH 8 ....................................... 47 5.5.1.2 Total ammonia concentration versus time at pH 9 ....................................... 48 5.5.1.3 Total ammonia concentration versus time at pH 10 ..................................... 48 5.5.1.4 Ammonia removal summary......................................................................... 49 5.5.2 Orthophosphate profile .................................................................................... 50 5.5.2.1 Orthophosphate concentration versus time at pH 8 ...................................... 50 5.5.2.2 Orthophosphate concentration versus time at pH 9 ...................................... 51 5.5.2.3 Orthophosphate concentration versus time at pH 10 .................................... 51 5.5.2.4 Orthophosphate removal summary ............................................................... 52 5.5.3 Magnesium profile ........................................................................................... 53 5.5.3.1 Total magnesium concentration versus time at pH 8 .................................... 53 5.5.3.2 Total magnesium concentration versus time at pH 9 .................................... 53 5.5.3.3 Total magnesium concentration versus time at pH 10 .................................. 54 5.5.3.4 Total magnesium removal summary............................................................. 55 5.5.4 Solution supersaturation ratio (SSR) ............................................................... 55 5.5.4.1 SSR at pH 8................................................................................................... 56 5.5.4.2 SSR at pH 9................................................................................................... 56 5.5.4.3 SSR at pH 10................................................................................................. 57 5.5.5 Struvite fines production (dissolution-reformation validation) ....................... 58 5.5.6 Caustic usage ................................................................................................... 59 5.5.7 Molar ratio comparison across solid products ................................................. 62 5.5.7.1 N:P ratio comparison of roasted versus uptake versus fine struvite ............. 62 5.5.7.2 N:Mg ratio comparison of roasted versus uptake versus fine struvite .......... 64 5.5.7.3 Mg:P ratio comparison of roasted versus uptake versus fine struvite .......... 65 5.5.8 Effect of temperature on molar ratios .............................................................. 67 5.5.8.1 Molar ratios versus temperature for constant pH 8 ....................................... 67 5.5.8.2 Molar ratios versus temperature for constant pH 9 ....................................... 69 5.5.8.3 Molar ratios versus temperature for constant pH 10 ..................................... 70 5.5.9 Effect of pH on molar ratios for constant temperatures ................................... 72 5.5.10 Mass balance .................................................................................................. 75 5.5.10.1 N balance .................................................................................................... 76 5.5.10.2 P balance ..................................................................................................... 76 5.5.10.3 Mg balance .................................................................................................. 77 5.5.10.4 Summary of mass balance results ............................................................... 77 vi  5.6 Uptake stage two: May 2010-August 2010 ........................................................ 77 5.6.1 Uptake experiments at constant pH 8 .............................................................. 78 5.6.1.1 Total ammonia concentration versus time at constant pH 8 ......................... 78 5.6.1.2 Ortho-phosphate concentration versus time at constant pH 8 ...................... 78 5.6.1.3 Magnesium concentration versus time at constant pH 8 .............................. 79 5.6.2 Uptake experiments at initial pH 8 with no control ......................................... 80 5.6.2.1 Total ammonia concentration versus time at initial pH 8 ............................. 80 5.6.2.2 Orthophosphate concentration versus time at initial pH 8 ............................ 81 5.6.2.3 Magnesium concentration versus time at initial pH 8 .................................. 82 5.6.3 Uptake experiments at constant pH 9 .............................................................. 83 5.6.3.1 Total ammonia concentration versus time at constant pH 9 ......................... 83 5.6.3.2 Orthophosphate concentration versus time at constant pH 9 ........................ 84 5.6.3.3 Magnesium concentration versus time at constant pH 9 .............................. 84 5.6.4 Molar ratios ...................................................................................................... 85 5.6.4.1 N:P ratios at pH 8 .......................................................................................... 85 5.6.4.2 N:Mg ratios at pH 8 ...................................................................................... 86 5.6.4.3 Mg:P ratios at pH 8 ....................................................................................... 87 5.6.4.4 N:P ratios at pH 9 .......................................................................................... 88 5.6.4.5 N:Mg ratios at pH 9 ...................................................................................... 88 5.6.4.6 Mg:P ratios at pH 9 ....................................................................................... 89 5.6.5 Full dissolution followed by reformation ........................................................ 90 5.7 Mass balance ....................................................................................................... 93 5.8 Specific uptake .................................................................................................... 93 5.9 SEM results ......................................................................................................... 95 5.10 Preliminary economic analysis ......................................................................... 97 6 Conclusions .................................................................................................................. 100 7 Recommendations ........................................................................................................ 102 References ....................................................................................................................... 104 Appendix A: Instrument operational parameters ............................................................ 107 Appendix B: Mass balance data ...................................................................................... 108 Appendix C: Elemental analysis spreadsheet ................................................................. 163 Appendix D: Mass balance graphs ................................................................................. 164 Appendix E: Economic analysis ..................................................................................... 178  vii  List of tables Table 1 Struvite benefit comparison case studies. .............................................................. 3 Table 2 Struvite crystallizer effluent characteristics. .......................................................... 4 Table 3 Content of NH4+ in magnesium phosphate sediment after drying or roasting in various temperatures for 24 hours..................................................................................... 14 Table 4 Feed solution makeup for 2009 and 2010. ........................................................... 21 Table 5 Percent mass recovery after sitting on lab bench for two weeks. ........................ 30 Table 6 Theoretical bulk sample identity after exposure to atmospheric moisture. ......... 30 Table 7 Observed and calculated mass loss and possible chemical formula immediately after heating. ..................................................................................................................... 34 Table 8 Observed and calculated mass loss and possible chemical formula two weeks after heating and exposure to the atmosphere. .................................................................. 35 Table 9 Structure comparison. .......................................................................................... 38 Table 10 Economic analysis. ............................................................................................ 98 Table A. 1 Magnesium AA operating parameters .......................................................... 107 Table A. 2 Lachat parameters for ammonia and phosphate............................................ 107 Table B. 1 2009 nitrogen balance 100°C ........................................................................ 108 Table B. 2 2009 nitrogen balance 120°C ........................................................................ 110 Table B. 3 2009 nitrogen balance 140°C ........................................................................ 112 Table B. 4 2009 nitrogen balance 160°C ........................................................................ 114 Table B. 5 2009 nitrogen balance 180°C ........................................................................ 116 Table B. 6 2009 nitrogen balance 200°C ........................................................................ 118 Table B. 7 2009 phosphorus balance 100°C ................................................................... 120 viii  Table B. 8 2009 phosphorus balance 120°C ................................................................... 122 Table B. 9 2009 phosphorus balance 140°C ................................................................... 124 Table B. 10 2009 phosphorus balance 160°C ................................................................. 126 Table B. 11 2009 phosphorus balance 180°C ................................................................. 128 Table B. 12 2009 phosphorus balance 200°C ................................................................. 130 Table B. 13 2009 magnesium balance 100°C ................................................................. 132 Table B. 14 2009 magnesium balance 120°C ................................................................. 134 Table B. 15 2009 magnesium balance 140°C ................................................................. 136 Table B. 16 2009 magnesium balance 160°C ................................................................. 138 Table B. 17 2009 magnesium balance 180°C ................................................................. 140 Table B. 18 2009 magnesium balance 200°C ................................................................. 142 Table B. 19 2010 mass balance summary for N, P, and Mg........................................... 144 Table B. 20 2010 nitrogen balance 80°C ........................................................................ 145 Table B. 21 2010 nitrogen balance 105°C ...................................................................... 147 Table B. 22 2010 nitrogen balance 160°C ...................................................................... 149 Table B. 23 2010 phosphorus balance 80°C ................................................................... 151 Table B. 24 2010 phosphorus balance 105°C ................................................................. 153 Table B. 25 2010 phosphorus balance 160°C ................................................................. 155 Table B. 26 2010 magnesium balance 80°C ................................................................... 157 Table B. 27 2010 magnesium balance 105°C ................................................................. 159 Table B. 28 2010 magnesium balance 160°C ................................................................. 161 Table C. 1 Elemental analysis solver .............................................................................. 163 Table E. 1 Heating-reformation method ......................................................................... 178  ix  Table E. 2 Sidestream nitrification method .................................................................... 179  x  List of figures Figure 1 Struvite process diagram. ..................................................................................... 7 Figure 2 Struvite uptake reactor with feed and heated struvite batch. .............................. 20 Figure 3 Struvite TGA curve – Percent mass remaining versus temperature. .................. 28 Figure 4 Percent struvite mass remaining over time for six different 24-hour heat treatments. ......................................................................................................................... 30 Figure 5 Struvite mass increase over time. ....................................................................... 31 Figure 6 Nitrogen content immediately after heating compared to after two weeks exposed to the atmosphere for six different temperatures and 24 hour duration. ............. 32 Figure 7 Water content immediately after heating compared to after two weeks exposed to the atmosphere for six different temperatures and 24 hour duration. ........................... 34 Figure 8 Effect of heating temperature on struvite nitrogen content for three different environments. .................................................................................................................... 35 Figure 9 Effect of heating temperature on struvite water content for three different environments. .................................................................................................................... 36 Figure 10 Effect of different environments on the nitrogen content in struvite heated at 105°C. ............................................................................................................................... 37 Figure 11 Effect of different environments on the water content in struvite heated at 105°C. ............................................................................................................................... 38 Figure 12 N:P ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture. ................................................................................... 40 Figure 13 N:Mg ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture. ................................................................................... 40 xi  Figure 14 Mg:P ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture. ................................................................................... 41 Figure 15 Percent mass remaining after 24 hours heating. ............................................... 42 Figure 16 Percent mass remaining versus time comparing size and morphology at a heating temperature of 100°C. .......................................................................................... 43 Figure 17 Percent mass remaining versus time comparing size and morphology at a heating temperature of 110°C. .......................................................................................... 43 Figure 18 Percent mass remaining versus time comparing size and morphology at a heating temperature of 120°C. .......................................................................................... 44 Figure 19 Mg:P vs. heating time for four temperatures. ................................................... 45 Figure 20 N:P vs. heating time for four temperatures. ..................................................... 45 Figure 21 N:Mg vs. heating time for four temperatures. .................................................. 46 Figure 22 Ammonia concentration for Gold Bar struvite at pH 8. ................................... 47 Figure 23 Ammonia concentration for Gold Bar struvite at pH 9. ................................... 48 Figure 24 Ammonia concentration for Gold Bar struvite at pH 10. ................................. 49 Figure 25 Orthophosphate concentration for Gold Bar struvite at pH 8........................... 50 Figure 26 Orthophosphate concentration for Gold Bar struvite at pH 9........................... 51 Figure 27 Orthophosphate concentration for Gold Bar struvite at pH 10......................... 52 Figure 28 Magnesium concentration for Gold Bar struvite at pH 8. ................................ 53 Figure 29 Magnesium concentration for Gold Bar struvite at pH 9. ................................ 54 Figure 30 Magnesium concentration for Gold Bar struvite at pH 10. .............................. 55 Figure 31 SSR vs. time for various temperatures at pH 8. ............................................... 56 Figure 32 SSR vs. time for various temperatures at pH 9. ............................................... 57  xii  Figure 33 SSR vs. time for various temperatures at pH 10. ............................................. 58 Figure 34 Percent fines produced versus isothermal heating temperature for pH 8, 9, and 10....................................................................................................................................... 59 Figure 35 Volume NaOH used vs. time for pH 8. ............................................................ 60 Figure 36 Volume NaOH used vs. time for pH 9. ............................................................ 60 Figure 37 Volume NaOH used vs. time for pH 10. .......................................................... 61 Figure 38 Total mmol NaOH used versus temperature for 3 pH values. ......................... 62 Figure 39 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8. ................. 63 Figure 40 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9. ................. 63 Figure 41 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10. ............... 64 Figure 42 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8. ................. 64 Figure 43 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9. ................. 65 Figure 44 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10. ............... 65 Figure 45 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8. ................. 66 Figure 46 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9. ................. 66  xiii  Figure 47 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10. ............... 67 Figure 48 N:P ratios versus temperature for pH 8. ........................................................... 68 Figure 49 N:Mg ratios versus temperature for pH 8. ........................................................ 68 Figure 50 Mg:P ratios versus temperature for pH 8. ........................................................ 69 Figure 51 N:P ratios versus temperature for pH 9. ........................................................... 69 Figure 52 N:Mg ratios versus temperature for pH 9. ........................................................ 70 Figure 53 Mg:P ratios versus temperature for pH 9. ........................................................ 70 Figure 54 N:P ratios versus temperature for pH 10. ......................................................... 71 Figure 55 N:Mg ratios versus temperature for pH 10. ...................................................... 71 Figure 56 Mg:P ratios versus temperature for pH 10. ...................................................... 72 Figure 57 Solid product molar ratios vs. pH for a heating temperature of 100°C. ........... 73 Figure 58 Solid product molar ratios vs. pH for a heating temperature of 120°C. ........... 73 Figure 59 Solid product molar ratios vs. pH for a heating temperature of 140°C. ........... 74 Figure 60 Solid product molar ratios vs. pH for a heating temperature of 160°C. ........... 74 Figure 61 Solid product molar ratios vs. pH for a heating temperature of 180°C. ........... 75 Figure 62 Solid product molar ratios vs. pH for a heating temperature of 200°C. ........... 75 Figure 63 NH4+ concentration vs time at pH 8. ................................................................ 78 Figure 64 PO43- concentration vs. time at pH 8. ............................................................... 79 Figure 65 Mg2+ concentration vs. time at pH 8. ............................................................... 80 Figure 66 Effect of no pH control on NH4+ concentration. .............................................. 81 Figure 67 Effect of no pH control on PO43- concentration. ............................................... 82 Figure 68 Effect of no pH control on Mg2+ concentration................................................ 82  xiv  Figure 69 NH4+ concentration vs. time at pH 9. ............................................................... 83 Figure 70 PO43- concentration vs. time at pH 9. ............................................................... 84 Figure 71 Mg2+ concentration vs. time at pH 9. ............................................................... 85 Figure 72 Solid product N:P ratios for uptake experiments at pH 8................................. 86 Figure 73 Solid product N:Mg ratios for uptake experiments at pH 8. ............................ 87 Figure 74 Solid product Mg:P ratios for uptake experiments at pH 8. ............................. 87 Figure 75 Solid product N:P ratios for uptake experiments at pH 9................................. 88 Figure 76 Solid product N:Mg ratios for uptake experiments at pH 9. ............................ 89 Figure 77 Solid product Mg:P ratios for uptake experiments at pH 9. ............................. 89 Figure 78 Effect of complete dissolution using acid prior to struvite crystallization for different heating temperatures and sample sizes. ............................................................. 90 Figure 79 Nitrogen balance for 10g complete dissolution and reformation for a heating temperature of 105°C. ....................................................................................................... 91 Figure 80 Nitrogen balance for 5.7g complete dissolution and reformation for a heating temperature of 160°C. ....................................................................................................... 91 Figure 81 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 80°C. ......................................................................................................... 92 Figure 82 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 160°C. ....................................................................................................... 92 Figure 83 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 105°C. ....................................................................................................... 93 Figure 84 2009 specific uptake versus heating temperature for three pH values. ............ 94 Figure 85 2010 specific uptake versus heating temperature at pH 8. ............................... 94  xv  Figure 86 2010 specific uptake versus heating temperature at pH 9. ............................... 95 Figure 87 Raw Gold Bar struvite interior 35x. ................................................................. 96 Figure 88 Heated Gold Bar struvite interior 70x. ............................................................. 96 Figure 89 Raw Gold Bar struvite interior 70x. ................................................................. 96 Figure 90 Raw Gold Bar Struvite cut 500x interior. ......................................................... 96 Figure 91 Heated Gold Bar struvite 500x interior. ........................................................... 96 Figure 92 Uptake pH 8.5 cut 500x interior. ...................................................................... 96 Figure 93 Uptake pH 8.5 cut 40x. ..................................................................................... 97 Figure 94 Uptake pH 10.5 cut 40x. ................................................................................... 97 Figure 95 Uptake pH 10.5 cut 500x interior. .................................................................... 97 Figure D. 1 2009 nitrogen mass balance @ T=100 for pH 8,9,10 .................................. 164 Figure D. 2 2009 nitrogen mass balance @ T=120 for pH 8,9,10 .................................. 164 Figure D. 3 2009 nitrogen mass balance @ T=140 for pH 8,9,10 .................................. 165 Figure D. 4 2009 nitrogen mass balance @ T=160 for pH 8,9,10 .................................. 165 Figure D. 5 2009 nitrogen mass balance @ T=180 for pH 8,9,10 .................................. 166 Figure D. 6 2009 nitrogen mass balance @ T=200 for pH 8,9,10 .................................. 166 Figure D. 7 2009 phosphorus mass balance @ T=100 for pH 8,9,10 ............................. 167 Figure D. 8 2009 phosphorus mass balance @ T=120 for pH 8,9,10 ............................. 167 Figure D. 9 2009 phosphorus mass balance @ T=140 for pH 8,9,10 ............................. 168 Figure D. 10 2009 phosphorus mass balance @ T=160 for pH 8,9,10 ........................... 168 Figure D. 11 2009 phosphorus mass balance @ T=180 for pH 8,9,10 ........................... 169 Figure D. 12 2009 phosphorus mass balance @ T=200 for pH 8,9,10 ........................... 169 Figure D. 13 2009 magnesium mass balance @ T=100 for pH 8,9,10 ........................... 170  xvi  Figure D. 14 2009 magnesium mass balance @ T=120 for pH 8,9,10 ........................... 170 Figure D. 15 2009 magnesium mass balance @ T=140 for pH 8,9,10 ........................... 171 Figure D. 16 2009 magnesium mass balance @ T=160 for pH 8,9,10 ........................... 171 Figure D. 17 2009 magnesium mass balance @ T=180 for pH 8,9,10 ........................... 172 Figure D. 18 2009 magnesium mass balance @ T=200 for pH 8,9,10 ........................... 172 Figure D. 19 2010 nitrogen mass balance @ T=80 ........................................................ 173 Figure D. 20 2010 nitrogen mass balance @ T=105 ...................................................... 173 Figure D. 21 2010 nitrogen mass balance @ T=160 ...................................................... 174 Figure D. 22 2010 phosphorus mass balance @ T=80 ................................................... 174 Figure D. 23 2010 phosphorus mass balance @ T=105 ................................................. 175 Figure D. 24 2010 phosphorus mass balance @ T=160 ................................................. 175 Figure D. 25 2010 magnesium mass balance @ T=80 ................................................... 176 Figure D. 26 2010 magnesium mass balance @ T=105 ................................................. 176 Figure D. 27 2010 magnesium mass balance @ T=160 ................................................. 177  xvii  Acknowledgements I would like to acknowledge the following people for their advice, assistance, and support during my time at UBC:  Dr. Don Mavinic for providing funding and invaluable advice as my supervisor. Fred Koch for the interesting conversations regarding ammonia recovery technologies and for providing alternative ways to view problems. Paula Parkinson, Tim Ma, and Larissa Lam for helping with my experiments and sample analysis. Dr. Parvez Fattah for sparking my interest in nutrient removal and recovery, and providing me practical training of running the pilot scale crystallizer. Lulu Island Wastewater Treatment Plant personnel for allowing me to conduct research and gain practical understanding of a nutrient recovery system. NSERC for providing me one year of funding through a CGS scholarship. Doug, Harald, Bill, and Scott for their help building my lab reactor components. Dr. Eric Hall for his generous help to purchase and learn BioWin. Dr. Pierre Berube for being our advisor for the AECOM design competition. Dr. Lo for reviewing my thesis. The PCWM graduate students for the companionship, and interesting discussions. My loved ones for the continuous support.  xviii  1 Introduction The primary sources of nitrogen in waste are feces, urine, and food-processing plants, with the majority existing as free ammonia, and the remainder is incorporated in organic material (Viessman & Hammer, 2004). At environmentally relevant pH values, unionized ammonia is acutely toxic to fish species, and therefore is cause for concern. An excess of nutrients in a water body has also been shown to cause eutrophication and eventual death of the aquatic ecosystem (Schindler, 1974). This has resulted in ammonia removal from waste streams becoming a key political priority in many jurisdictions around the world.  Ammonia can be removed by primary treatment and secondary biological treatment in which the activated sludge contains about 6% nitrogen by mass (Viessman & Hammer, 2004). After digestion, the nitrogen content is reduced to approximately 4%. Anaerobic sludge digestion has been found to release much of the nitrogen and phosphorus contained in the biosolids, back into the waste stream in concentrations much higher than in the influent (Britton et al., 2005). Unfortunately, if magnesium is present in the influent, the solution may become supersaturated with respect to magnesium ammonium phosphate, commonly known either as MAP or struvite, and spontaneous crystallization in digester pumps and pipes is likely to occur (Fattah et al., 2008). Hydraulic capacity becomes compromised and pumping and maintenance costs increase, since acid must be flushed through the pipes to dissolve and remove the encrustation. Plants also risk noncompliance with nutrient discharge limits.  1  Controlled production of struvite can be advantageous for any biological nutrient removal (BNR) plant and easily fits into existing solids processing facilities. By harvesting struvite, hydraulic capacity is maintained and maintenance costs are reduced. As the phosphate content in biosolids is decreased, sludge volume may also be reduced by up to 30% or 49% compared to EBNR and chemical phosphorus precipitation, respectively, which minimizes final disposal costs (Woods et al., 1999). Also, phosphorus and nitrogen loads on the plant are reduced, which diminishes the amount of chemical polishing required, as well as aeration (Britton et al., 2007).  Pilot studies at five treatment plants have shown exceptional removal and recovery of phosphorus (Table 1). Phosphorus and nitrogen concentration can be reduced by up to 95 and 20 percent, respectively. Maximum reduction in phosphorus and nitrogen loading on any plant was 30 and 10 percent, respectively. Additional cost savings on acid flushing can be significant. For example, the Gold Bar Treatment Plant saved $100,000 per year after implementing a pilot project.  A life cycle analysis of wastewater-derived struvite fertilizer production at the 68.7 mgd, Gold Bar WWTP, found that approximately 12,000 tonnes of carbon dioxide emissions per year can be offset versus conventional fertilizer production, largely due to the mining, thermal processes and long transport distances required by the latter (Britton et al., 2007). The struvite pellets produced are a highly pure, slow-release fertilizer suitable for sale in the $1B per year container nursery market (Baur, 2009). In Japan, the market price was $375 USD per tonne after three years’ experience of operating and selling recovered  2  struvite from a full scale plant (Ueno & Fujii, 2001). In North America, the market price is still under flux but has reached as high as $3000 USD per tonne (Mavinic, 2010). Thus, nutrient recovery benefits both the environment and the process integrity, while providing a significant revenue stream for the treatment plant owners.  Table 1 Struvite benefit comparison case studies.  Treatment Plant  Flow  Influent Influent P N P load N load Struvite P N removal removal reduction reduction Prod.  Yearly Rev.  Gold Bar  mgd 68.7  Nansemond  18.3  Durham  20  (mg/L) 207 140700 600  Penticton  5.6  37-71  Lulu Island  21.1  39-88  (mg/L) 805 500800 1200 197436 410907  (%) 75  (%) 20  (%) 20  (%) 5  (t/yr) 1200  ($ mill) 3.6  80  42  30  10  1650  4.9  95  19  24  6  430  1.3  91  10  N/A  N/A  N/A  N/A  90  4  N/A  N/A  N/A  N/A  Pilot and full scale studies have been shown to completely remove and recover phosphorus from the feed streams. However, nitrogen concentrations are usually in large excess and can still result in harm to the receiving waters. Typically, remaining ammonia is removed by recycling the effluent back into the biological process for conventional nitrification-denitrification (Turker & Celen, 2007). Other methods include side stream nitrification, breakpoint chlorination, ion-exchange, electrodialysis, evaporation, and reverse osmosis (Stefanowicz et al., 1992), as well as physical adsorption onto activated carbon and zeolite materials (Fumoto et al., 2009). These technologies are limited in use to particular pH conditions and initial influent concentrations and high temperatures. Furthermore, at concentrations near 1000 mg/L and volumes near 70 m3, the capital and operating costs become too high (Stefanowicz et al., 1992). A sustainable approach, 3  based on nitrogen recovery, is ideal to stabilize the overall nitrogen balance and to potentially reduce the overall economics cost of the wastewater treatment plant (Turker & Celen, 2007).  To overcome the disadvantages of the aforementioned nitrogen removal technologies, it was hypothesized that struvite pellets can be heated to thermally decompose struvite, removing ammonia and water from the crystal. Decomposed pellets can then act as an aqueous ammonium removal agent, restoring the crystal back to its original chemical form. This recycling process can theoretically continue until the excess ammonia is completely removed.  In this research, a synthetic feed solution, with concentrations similar to effluent from Lulu Island Waste Water Treatment Plant (LIWWTP), was used to simulate the effectiveness at relevant and realistic concentrations (Table 2). It is believed that amorphous newberyite can be recycled back into the MAP crystallizer to reform crystalline struvite (Equation 1).  MgHPO4 (s) + NH3 (aq) + 6H20  MgNH4PO4●6H20 (s) (Equation 1) Table 2 Struvite crystallizer effluent characteristics.  Component  2009 Concentration Molar ratio  2010 Concentration Molar ratio  N  300 mg/L  N:P = 65:1  700 mg/L  N:P = 150:1  P Mg  10 mg/L 30 mg/L  Mg:P = 37:1 N:Mg = 4.2:1  10 mg/L 30 mg/L  Mg:P = 37:1 N:Mg = 4.2:1  4  2 Research objectives The purpose of this research was to initiate the development of a nitrogen removal technology. This was to be achieved through the thermal decomposition of struvite and subsequent placement of the decomposition product into an ammonia-rich solution, at concentrations that are typical of UBC/Lulu Island pilot struvite crystallizer effluent.  The decomposition reaction is dependent on the temperature, atmospheric conditions, heating duration, oven size and type, and the sample size. A key objective was to gain a better understanding of struvite decomposition variables and the reaction mechanism so that struvite decomposition could be optimized.  To fully develop a nitrogen recovery technology, an understanding of the conditions necessary to uptake ammonia is required. Another key objective was to determine optimal pH conditions, reaction durations, reactant mass, and heating temperatures, in order to maximize ammonia uptake into heated struvite pellet, while minimizing the competing production of fine struvite.  The final objective was to provide an initial understanding of the economic viability of the process compared to sidestream nitrification.  5  3 Literature review A review of struvite chemistry in terms of thermal stability is presented This is followed by a review of analytical detection techniques and aqueous ammonia removal methods.  3.1 Solution equilibria Pure ammonia in solution exists as two species: unionized ammonia (NH3) and ammonium ion (NH4+). The relative proportion of these two species is dependent on the pH of the solution. Phosphate in solution exists as four species: phosphoric acid (H3PO4), dihydrogen phosphate (H2PO4-), hydrogen phosphate (HPO42-), and orthophosphate (PO43-). The relative proportion of these four species is also dependent on the pH of the solution. Magnesium exists in solution in the cationic form with a hexahydrate shell (Mg2+●6H2O). However, at basic pH values, magnesium cation can become bound to the hydroxyl ion in various ways.  3.2 Struvite chemistry The mineral magnesium ammonium phosphate hexahydrate (MgNH4PO4●6H2O) is known commonly as struvite. A pure crystal contains equimolar amounts of magnesium, ammonium and orthophosphate, along with six waters of hydration. Depending on solution pH, the formation of struvite can occur through two competing reactions (Equation 2-3). Mg2+ + NH4+ + HPO42- + OH- + 5H2O  MgNH4PO4●6H20 (Equation 2) Mg2+ + NH4+ + H2PO4- + 2OH- + 4H2O  MgNH4PO4●6H20 (Equation 3)  6  3.3 Struvite (MAP) process In 1999, BC Hydro provided funding for the University of British Columbia to initiate research into nutrient recovery from wastewater. BC Hydro was interested in technologies that could lead to discoveries of new sources of fertilizers for use in nutrient deprived lakes and rivers. The UBC teams’ solution was to channel anaerobic digester centrate or supernatant to a dedicated sidestream fluidized bed reactor for controlled crystallization of struvite. The process shown in Figure 1 involves centrate or supernatant influent entering the injection port and mixing with a magnesium source and a caustic source, to precipitate struvite out of solution. The fluidized bed reactor maintains a constant and sufficient upflow velocity to allow for crystal growth and agglomeration into a large pellet that can be harvested when desired. The success in the removal of phosphorus from the wastewater has allowed this process to be commercialized and several full scale plants now operate throughout the world. However, the process performs poorly in removing ammonia from solution, when an excess of ammonia exists in the centrate or supernatant.  Figure 1 Struvite process diagram.  7  3.4 Ammonia as an energy source The recovery of ammonia from wastewater benefits the treatment plant, but also can be viewed as a source of energy (Christensen et al., 2005; Klerke et al., 2008). Gaseous ammonia can be trapped in an acidified solution of sodium borohydride (NaBH4) via Equation 4.  NH4+ + BH4-  NH4BH4 (Equation 4)  Ammonium borohydride, provides storage of hydrogen on both the ammonium cation and the borohydride anion. This solid compound also contains the highest gravimetric hydrogen density at approximately 24%. It has been found that 20 wt% of hydrogen is released at temperatures lower than 160°C (Karkamkar et al., 2009). Thus, the release of ammonia from heated struvite, and subsequent storage in borohydride, may play a role in the hydrogen economy.  Alternately, gaseous ammonia can be trapped in magnesium chloride, forming magnesium hexammine chloride Mg(NH3)6Cl2 (Jacobsen et al., 2007; Christensen et al., 2006). This compound can be thermally decomposed to magnesium chloride and recycled back to the struvite crystallizer, to remove remaining ammonium ions from solution.  3.5 Struvite thermal decomposition It is important to understand the thermal stability and phase transitions of struvite and related compounds in order to more effectively produce pure agriculturally desired  8  fertilizer products (Bhuiyan et al., 2008). This knowledge is also useful in developing an ammonium recovery technology using recycled, thermally decomposed struvite. It has been proposed by many researchers that heating struvite results in the expulsion of the six waters of hydration and the chemically bound ammonia (Equation 5), forming magnesium hydrogen phosphate, commonly known as newberyite (Sugiyama et al., 2005; Frost et al., 2004; Wang et al., 2006).  MgNH4PO4●6H20 (s) + heat  MgHPO4 (s) + NH3 (g)↑+ 6H20 (g)↑ (Equation 5)  3.5.1 Thermal mass loss The calculated mass loss is used to qualitatively determine the average composition of struvite after heating. The theoretical mass loss for struvite based on Equation 5 is 51.42% (44.08% water, and 7.34% ammonia). It was found that, between 100-140 °C, the mass lost was stable at approximately 45% for any duration two hours or longer, indicating that increasing the time for heating does not significantly increase the mass lost (Frost et al., 2004; Wang et al., 2006).  3.5.2 Thermal gravimetric analysis (TGA) Struvite decomposition is dependent on the local atmospheric conditions (ie. nitrogen atmosphere versus moist atmosphere) (Frost et al., 2004). Using a TGA, it was found that struvite originating in human kidneys or urinary tracts, or guano formations, decomposed at 85°C when heated at a rate of 2°C/min. The reaction product was not identified. Sarkar (1991) however, found that struvite decomposed at approximately 106°C, when heated at a rate of 5°C/min. Wang et al. (2006) found that struvite decomposed between 1009  140°C, although the heating rate was not stated. All three groups found only one peak in the differential TGA curve, suggesting that water and ammonia are simultaneously released.  When the heating rate was decreased to 1°C/min, Frost et al. (2004) found that the decomposition occurred at three distinct temperatures: 39.5, 57.8, and 82.6°C. Struvite decomposition is highly dependent on heating rate. This results in a contradictory hypothesis in which ammonia is first released, followed by the waters of crystallization. The waters of crystallization are hypothesized to be strongly hydrogen bonded to the magnesium cation because a strong infrared OH stretching band is observed on samples of heated struvite (Cahil et al., 2007). The crystallographic data shows that the water molecules in struvite form donor hydrogen bonds, which are of the shortest length for all known minerals.  (Bhuiyan et al. 2008) studied the thermal decomposition of struvite in dry air and observed a conversion to amorphous newberyite. The decomposition of struvite was highly dependent on the rate of heating, with slower rates of heating achieving maximum rate of decomposition at lower temperatures.  3.5.3 Thermo-gas (TG) titrimetry Non-isothermal analytical methods, such as TGA, do not reflect the real nature of transformation because the thermal analytical curves are characteristic of heat and gas transport processes, rather than the intrinsic transformation process (Paulik, 1999). Heat transfer is the slowest process and thus controls the rate of mass loss (Paulik & Paulik, 10  1975). They determined the composition and course of the elementary partial struvite decomposition reactions, as well as how the elementary partial reactions are influenced by experimental conditions by using simultaneous thermo-gas titrimetry (TG) and evolved gas analysis (EGA). Quasi-isothermal and quasi-isobaric conditions, and were used to detect the changes in the different gaseous decomposition products evolved. The technique operates as follows: The temperature inside the furnace heats up at a fast rate until the sample begins to decompose and lose mass. This sends an electrical signal to the furnace shutting it off until the rate of mass change decreases at which point the furnace heats up again. This essentially provides for the quasi-isothermal decomposition conditions such that the thermal analytical curve is not erroneously dictated by heattransfer. The evolved gas is trapped in water. A potential difference develops between the pH electrodes, which induces an automatic burette to titrate the ammonia-water solution with hydrochloric acid. The strength of this method is the overlapping decomposition reactions are separated in space and time. It was found that five moles of crystallization water leave the crystal first followed by one mole of crystallization water. The third step involves simultaneous release of ammonia and the water of constitution. It was interesting to note that approximately 5% of ammonia was calculated to leave the struvite crystal at the onset of heating. The mechanism proposed shows the final product as magnesium pyrophosphate (Equation 6-8), rather than amorphous newberyite.  MgNH4PO4●6H20  MgNH4PO4●H20 + 5H20 (Equation 6) MgNH4PO4●H20  MgNH4PO4 + H20 (Equation 7) 2MgNH4PO4  Mg2P2O7 + 2NH3 + H2O (Equation 8)  11  Paulik (1999) also found that struvite decomposition depends on water vapour pressure. At a high vapour pressure, the hypothesized mechanism does not require the middle elementary reaction (Equation 7) and instead proceeds via Equations 9-10.  MgNH4PO4●6H2O = MgNH4PO4●H2O + 5H2Of (Equation 9) 2MgNH4PO4●H2O = Mg2P2O7 + 3H2O + 2NH3 (Equation 10)  At a lower water vapour partial pressure, the decomposition was found to take place in one step (Equation 11).  2MgNH4PO4●6H2O = Mg2P2O7 + 13H2O + 2NH3 (Equation 11)  3.5.4 Evolved gas analysis (EGA) Evolved gas analysis (EGA) and combined differential thermal analysis mass spectrometry (DTA/MS) can be used to determine the type and amount of gaseous reaction products during heating of minerals. Muller-Vonmoos et al. (1977) used a thermoanalyzer, combined with a quadrupole mass spectrometer, to perform simultaneous DTA, TGA and evolved gas analysis. During heating, weight loss occurs and the evolved gases are instantly quantitatively detected by the mass spectrometer. The location of evolved gas peaks has been shown to be dependent on the degree of saturation of the bulk material (Yariv et al., 1989). This effect may interfere with the analysis of heated struvite and struvite after an uptake experiment, in which water may be adhered to the pellets. Koel et al. (1997) found that it is more appropriate to analyze the evolved gases using thermogravimetry/gas chromatography (TG/GC) and designed an instrument 12  by connecting a low volume furnace to a gas chromatograph interfaced by a computer controlled pneumatic sampler. The spectrum produced is called a thermochromatograph because evolved gases can be resolved into components according to two independent variables, namely, temperature and time. There are two main drawbacks to this method. The instrument is not very sensitive when the evolved gases make up only a small proportion of the total mass. This was not a problem with the heating of struvite, which theoretically loses 51.42% mass. Also, the monitoring is “pseudocontinuous” as the evolved gases take time to go through the GC and, thus, mixing can occur. Overlapping decomposition processes were separated using factor analysis and principle component analysis (PCA). Koel et al. (1998) successfully separated and detected the evolved gases from an ammonium salt finding that 73.7% of water evolved between 90-190°C, and 23.1% water evolved simultaneously with 100% of ammonia between 240-320°C. The remaining 3.2% of water evolved between 450-570°C.  3.5.5 Inductively coupled plasma (ICP) spectroscopy Two ICP methods were developed for nitrogen determination in fertilizers, although they have never been tested on struvite. Nham (1993) developed an ICP-AES method for direct nitrogen determination in fertilizer. This removes the time consuming digestion period, which is usually required in colorimetry analysis. Jaber et al. (2009) improved the technique by removing matrix interferences by incorporating a hydride generator system (ICP-AES-HG). This technique reduced the problems with background nitrogen levels in the air and in solution that plagued the first method. The mean values of N, using both methods, matched well with the standard colorimetric method.  13  3.5.6 Fourier transform infrared spectroscopy (FT-IR) Banks et al. (1975) used FT-IR measurements to track the composition of the solid phase during the aqueous conversion process of struvite to newberyite. The characteristic band of absorbance for struvite is at 1442 cm-1 (v4 NH4+ bending mode). Babic-Ivancic et al. (2006) used this result in conjunction with IR spectra for newberyite (peaks at 1237, 1171, and 890 cm-1), to present a semi-quantitative estimate of the ratio of newberyite to struvite in a solid mixture using FT-IR. Well-defined mixtures of struvite and newberyite were prepared and a calibration curve was constructed by plotting the absorbance of the struvite bands versus the proportion by mass of struvite in the sample. This method may be useful for determining percent struvite versus percent newberyite composition after heating, assuming that the thermal conversion is in fact struvite to newberyite. This method may also be useful for determining the success of ammonium removal into pellets.  3.5.7 Ammonium content using distillation and titration  The ammonia remaining in the solid was analyzed by distillation and titration in HCl solution (Stefanowicz et al., 1992). Ammonia was observed to be released even at low temperatures (Table 3). The identity of the roast product was stated as Mg3(PO4)2 rather than amorphous newberyite. However, the researchers did not analyze the roast product to determine its chemical identity. Table 3 Content of NH4+ in magnesium phosphate sediment after drying or roasting in various temperatures for 24 hours.  Heating temperature (°C) 50 100  Content of NH4+ (%) 2.7 1.2 14  Heating temperature (°C) 150 250  Content of NH4+ (%) 0.4 0  3.5.8 31P Magic angle spinning nuclear magnetic resonance (31P MAS NMR) Sugiyama et al. (2005) heated struvite samples for 3 hours and found (using XRD) that, between 100 and 150°C, the hexahydrate was converted to monohydrate. Between 200 and 500 °C, an essentially amorphous XRD pattern was observed. Structural information of amorphous phases cannot be determined using XRD, necessitating the use of solid state 31P MAS NMR. Using this technique, it was shown that the amorphous compounds between 200 and 500 °C correspond to MgHPO4. Above 800°C, XRD has been shown to convert to Mg2P2O7 (Paulik, 1999). This result suggests that Mg3(PO4)2 is not formed as suggested by (Stefanowicz et al., 1992).  3.5.9 Heating in acid and alkali solutions He et al. (2007) heated struvite in an alkali solution (NH4+:OH- 1:1) for 2 hr at 90°C, forming MgNaPO4. Upon re-introduction into an ammonium solution, the Na+ ion substituted for NH4+, because Na+ is a less stable univalent cation than NH4+. Results show that, after 6 reuse cycles, ammonium removal was maintained at 84%.  Alternately, Zhang et al. (2004) found that MAP powder can release ammonium to form MgHPO4 at pH < 5.0 and heating temperatures greater than 40°C. The resulting decomposition residues effectively removed ammonium from solution. However, this method allowed about 4% of phosphate and magnesium loss. The molar ratio of N:P  15  increased dramatically with the increase of temperature from 25°C to 40°C, indicating that ammonium was selectively released from MAP under a relatively high temperature. So, a high temperature was not only preferable for ammonium release, but also for keeping phosphate in the residual precipitations.  3.6 Aqueous recovery of ammonium Sarkar (1991) found that struvite is thermally unstable in air at temperatures above 50°C and loses part or all of its ammonia and water molecules, depending on the time and temperature of heat treatment. Ultimately, magnesium hydrogen phosphate was suggested to form from the decomposition of dittmarite, which is thermodynamically more stable than struvite. Upon room-temperature rehydration, struvite was reformed along with unknown hydrates and newberyite, depending on the amount of ammonia left in the structure.  3.6.1 Struvite and newberyite solubility The solubility products of newberyite and struvite are shown in Equation 12 and Equation 13, respectively (Ohlinger et al., 1999; Taylor et al., 1963). The magnitude of newberyite solubility is much greater than struvite solubility. Heated struvite is likely to be more soluble than newberyite as both ammonia and crystalline water are no longer holding the crystal together. Effectively, heated struvite acts as a source of magnesium and phosphate ions.  Ksp(newberyite) = 1.58E-6  Pksp (newberyite) = 5.80 (Equation 12) Ksp (struvite) = 5.37E-14  pKsp (struvite) = 13.27 (Equation 13) 16  3.6.2 Solution-mediated reformation mechanism Babic-Ivancic et al. (2006) argue that a solution-mediated conversion process is the most plausible transformation mechanism for struvite to newberyite. A precipitation diagram was constructed which showed the approximate concentration regions where struvite, newberyite, and their mixtures exist at room temperature. The ratio of initial supersaturation ratios of struvite to newberyite (Sstruvite/Snewberyite) had a strong influence on the struvite to newberyite conversion. Boistelle et al. (1983) previously found that struvite always crystallizes first when Snewberyite/Sstruvite has a value less than 2. It was also found that for Snewberyite/Sstruvite greater than 4, newberyite crystallized first, and for ratios between 2 to 4, the first phase to crystallize was dependent on the initial pH value. It was further found that newberyite is formed and most stable at excess Mg concentrations and low pH values. This presents a trade off; Newberyite is preferentially formed in solution at pH values of approximately 6.58, and the preformed struvite pellets dissolve into the solution.  3.6.3 Dissolution reformation mechanism Sugiyama et al. (2005) argue in favour of a similar mechanism known as dissolutionprecipitation. They found that ammonium was better removed at pH 8 rather than pH 10, because newberyite is more soluble at lower pH. The solubilized ions are hypothesized to react with aqueous ammonium, forming struvite. It was shown that, by allowing the pH to drop from 8 to 6 during uptake, ammonium removal of up to 93% can be achieved. Finally, Sugiyama et al. (2009) found that increasing the mass of newberyite placed in the reactor caused an increase in the ammonium removal. This may because a larger mass of struvite acts as a bigger source of magnesium and phosphate ions. 17  3.6.4 Complete acid dissolution reformation mechanism Stefanowicz et al. (1992) introduced heated struvite into ammonia water (1000 mg/L) and lowered the pH to a value of 1-2. The solid was completely dissolved, releasing aqueous magnesium and phosphate into solution. Caustic solution was added to increase the pH back to a value 9-10, causing the reformation of MAP, and the lowering of ammonia concentrations to below 1mg/L. The best conditions were when the reaction time was five hours or more. The specific ammonia removal rate was approximately 71.4 mg N/ g roast product.  3.6.5 Gaseous adsorption Activated carbon and zeolite adsorbents have been used to recover ammonia gas (Fumoto et al., 2009). These adsorbents are not ideal because of the high temperatures needed to desorb ammonia. Evolved gaseous ammonia and water were measured using quadrupole mass spectrometry with m/z 15 and 18, respectively. Heated MAP exhibited hysteresis and thus was shown to contain pores. Bigger pores were observed at 105°C compared to 300°C. Gaseous ammonia was best absorbed at lower temperatures.  18  4 Materials and methods The basic experimental design and research methodology is presented. Heating, drying, aqueous uptake, and analysis are outlined.  4.1 Reactor design The bench-scale reactor was rectangular with inside dimensions 11.5cm X 11.5cm X 20.5cm as shown in Figure 2. A rectangular impeller with dimensions 10cm X 4cm X 0.3cm stirred the reactor contents and was powered by a Dayton® DC gear motor (1/30 hp, 90V, 0.42A). A pH probe (Oakton® WD-35801-00 epoxy body) was mounted inside the reactor in order to monitor the pH continuously. The pH probe used was calibrated with three pH standards (pH 4, 7, and 10). The pH probe was interfaced to a Fischer Scientific Accumet® pH meter 50, which read the pH values electronically. The probe was calibrated before each experiment. A conductivity meter (Oakton® TDS/Conductivity/°C metre Conio Series) measured the temperature and conductivity of the feed solution. A separate hole was drilled into the top of the reactor to allow for caustic addition with a 1ml syringe. Two batches of caustic were made (1M and 6M) in order to increase the pH quickly or more slowly in the reactor, respectively.  19  Figure 2 Struvite uptake reactor with feed and heated struvite batch.  4.2 Thermally decomposing struvite Struvite was selected from a large batch obtained from the Gold Bar WWTP and sieved through a No. 8 (2.36mm) and retained on a No. 10 (2.0mm). Thus, all struvite pellets for heating were between the size range of 2.0mm-2.36mm. Two different ovens were used throughout the duration of the experiments, because the first oven broke. The oven used in the Part 1: 2009 experiments was a Fisher Isotemp 2.5 cubic foot forced air model, and the oven used in the Part 2: 2010 experiments was a Lab Line L-C model. Struvite was heated isothermally at temperatures ranging from 40 to 200°C, for durations ranging from 30 minutes to 24 hours. After heating, struvite was either placed on the lab bench to cool to room temperature, and to achieve stable mass, or was placed in the vacuum desicator to achieve stable mass.  4.3 Feed solution characteristics The feed solution was made with the following ingredients: 20  Magnesium chloride hexahydrate, MgCl2●6H2O (CAS 7791-18-6) Sodium dihydrogen phosphate, Na2HPO4 (CAS 7558-79-4) Ammonium chloride, NH4Cl (CAS 12125-02-9) DI water: 18.6 μS/cm The feed solution for Part 1 and Part 2 are shown in Table 4. Table 4 Feed solution makeup for 2009 and 2010.  Species Mg N P pH  Part 1: 2009 30 300 10 6.63-7.08  Part 2: 2010 30 700 10 6.65-6.76  4.4 Aqueous uptake experiments Feed solution was added to the reactor using a 1L graduated cylinder in 2009 and with a 500 ml volumetric flask in 2010 with quantities of 750ml and 500ml, respectively. The initial pH of the solution was measured. The temperature and conductivity of the feed solution was also measured. A 5ml aliquot of the feed solution was drawn directly from the reactor using a 5ml volumetric pipette. The contents were emptied into a small test tube and two drops of H2SO4 were placed into the test tube to reduce to pH<2 for sample preservation. The pH in the reactor was then increased using 6M NaOH for rapid increase, and 1M NaOH for precisely achieving the appropriate pH value defined. For the 2009 experiments, once the pH setpoint was reached, a 30 ml syringe was used to take an aliquot of solution at the pH setpoint and the contents were filtered (Whatman® cellulose nitrate membrane filters 0.45μm 25mm diameter) into a 5ml test tube and preserved with two drops of H2SO4. A similar procedure was conducted for the 2010 experiments except that a 5ml volumetric pipette was used to accurately obtain the aliquot. Also, if any crystallized struvite was found attached to the paper, it would be placed back into the 21  reactor so that the crystals would re-enter the solution. A 5ml aliquot of the adjusted feed was drawn from the beaker and placed in a test tube and preserved with two drops of H2SO4. This sample served as the baseline for the initial mass of magnesium, nitrogen, and phosphorus. An aluminum dish was tared on a balance and the appropriate mass of heated struvite was placed into the dish. The moment this struvite was placed into the reactor, was assigned as the start time of the uptake experiment. Every 15 minutes, for a duration of two hours, a 5ml sample was taken from the reactor using the respective procedures (ie. 2009, and 2010), so that a time series of the reaction progress could later be plotted. During the uptake experiment, the pH would decline as struvite was being formed. The pH was maintained by dropping 1M NaOH through the top of the reactor using a 1ml syringe. At the end of the 2 hour period, the solution was vacuum filtered through a 10 cm ceramic Buchner funnel using a filter paper with 50μm pore size (Whatman® 50 Hardened 9cm diameter). The filtrate was used to wash the retained pellets and reactor surfaces twice in order to remove any fine struvite that may be adsorbed to the surfaces. The pellets were then transferred to a stacked series of three sieves and a pan with mesh decreasing in diameter. The sieves had mesh diameter 1mm, 500μm, and 250μm (No. 18, 35, 60), respectively. The filtrate was used to wash the reactor surfaces one more time before the final filtration. The fine struvite were retained on the filter paper and dried.  4.5 Pellet drying and collecting The pellets and fine struvite were dried at room temperature for a minimum of 24 hours on the stacked series of sieves (No.18, No.35, and No.60) and filter paper, respectively.  22  The sieves were shaken so that any small crystals were separated and retained on the appropriate sieve. The mass of struvite remaining on each sieve and the pan was taken, and then each component was stored in a sample bag (Nasco Whirl-pak®). The fine struvite retained on the filter paper was scraped off the filter paper and into an aluminum weigh dish using an aluminum spatula. Some samples were stored in a LABCONCO vacuum desicator at 17mm Hg, while others were stored on the lab bench. This was because the vacuum desicator was found not sufficient to prevent water from reabsorbing to the surface of the pellets and fines.  4.6 Struvite product sample preparation Three different types of struvite were analyzed: struvite pellets that had gone through a heating procedure only, struvite pellets that had gone through a heating procedure and an uptake procedure, and struvite fines which carried through the heating and uptake procedure or were newly formed during the uptake period. The samples were finely crushed using a ceramic mortar and pestle; approximately 40 mg or 200mg were placed in a 250ml volumetric flask during 2009 and 2010 experiments, respectively. One pipette full (approximately 30 drops) of concentrated HCl (CAS No: 7647-01-0) was placed into the flask to reduce to pH 2, and then was DI water (18.6 μS/cm) was added to make up the volume. The flask was shaken by hand and was allowed to digest the struvite sample for a minimum of 24 hours or until all solid material was dissolved and no longer visible. The contents were then transferred to a centrifuge tube for storage.  23  4.7 Aqueous analytical methods Analytical methods for detection of magnesium, ammonia-N, and orthophosphate are outlined here. The instrument operational parameter details are provided in Appendix A. 4.7.1 Magnesium Samples were diluted appropriately with DI water. Nitric acid was used for preservation and lanthanum nitrate was used as an internal standard. The prepared sample was mixed using a vortex (Scientific Industries Vortex-Genie 2). Magnesium analysis was done using flame atomic absorption spectrophotometry with a Varian Inc. SpectraAA 200 Fast Sequential Atomic Absorption Spectrophotometer and a Varian SPS5 Sample Preparation System. A five point calibration curve was constructed. 4.7.2 Ammonia-N Samples were diluted appropriately using DI water. The samples were analyzed using flow injection analysis with a Lachat Instruments QuikChem 8000 attached to a Lachat Instruments XYZ autosampler ASX-500 Series.  4.7.3 Orthophosphate Samples were diluted appropriately using DI water. The samples were analyzed using flow injection analysis with a Lachat Instruments QuikChem 8000 attached to a Lachat Instruments XYZ autosampler ASX-500 Series.  4.8 Molar ratios The molar ratios for the three components of struvite are calculated in order to determine the success of reactions. N:P, N:Mg, and Mg:P ratios for each of the three solid “types” 24  of struvite were calculated using results from aqueous ammonia-N, aqueous orthophosphate, and magnesium data for each experiment.  4.9 Mass balance Mass balance of total N, P, and Mg in struvite was conducted from raw struvite, heated struvite, through to reformed struvite in solution. The mass balance spreadsheets can be found in Appendix B.  4.10 Heated pellet dissolution in DI water To quantify the confounding effect of natural pellet dissolution, heated struvite samples were placed in DI water and the pH adjusted to 8-10 and then mixed for 15 minutes to determine how much of the pellet dissolves when no feed solution is present. The concentration of the three struvite components was measured in the water and mass balance was also calculated.  4.11 Elemental analysis (EA) Elemental Analysis was conducted on solid samples of heated struvite, uptake struvite, and fine struvite. The percent of C, H, and N was determined using the UBC Chemistry Departments FISONS Instruments EA1108 equipped with an AS-200LS autosampler, a combustion oven packed with oxidation catalyst and metallic copper wires, a PorapakQ GC column, and a thermal conductivity detector. The structural identity of the sample was identified by simultaneous solution of a system of two equations and two unknowns using Microsoft Excel Solver function as shown in Appendix C. The unknown “x” corresponds to fractional ammonia in the crystal where “x” ranges from 0-1 (Equation 25  14). The unknown “y” corresponds to the fractional water in the crystal where “y” ranged from 0-6 (Equation 15).  MgH(NH3)xPO4(H2O)y % N: (14)X/[(17)X + Mass of MgHPO4 + (18)y] (Equation 14) % H: [1+2y+3x]/[(17)X + Mass of MgHPO4 + (18)y] (Equation 15)  4.12 Impurities – Total inorganic carbon and elemental analysis The chemical formula for pure struvite is MgNH4PO4●6H2O. However, impurities usually make up a small fraction of a pellet. Total Inorganic Carbon analysis was conducted by weighing five grams of solid sample and dissolving into 30 ml of DI water using an ultrasonic mixer. It was found that struvite formed at the Gold Bar Treatment Plant contained approximately 0.03-0.22% carbon. This agrees quite well with elemental analysis, which found that carbon accounts for 0.18-0.35 % of the total mass.  4.13 Scanning electron microscopy (SEM) analysis The surface morphology of struvite pellets were examined by scanning electron microscope, using the UBC Materials Engineering Hitachi S-3000N SEM. The pellet sample was placed in epoxy resin and left to cure, followed by polishing. The oval shaped pellet was polished down so that the interior of the struvite was exposed at the surface of the resin holder.  26  5 Results and discussion The results of both heating experiments and uptake experiments for both 2009 and 2010 research seasons are given. Comparison to prior research is outlined accordingly.  5.1 Thermal decomposition It is important to understand the mechanism of ammonia and water loss during heat treatment in order to begin optimizing this ammonia recovery technology. Three complementary approaches were utilized to understand the mechanism including: mass loss curves, solid elemental analysis, and wet-chemical analysis (orthophosphate, ammonium-N, and total magnesium).  5.1.1 Mass loss curves The mass loss of heated struvite was analyzed using thermogravimetric analysis (TGA) after 24 hour isothermal heat treatment in a thermostatted oven. A TGA was run at 1°/min under moist atmospheric conditions (ie. STP). The total percent mass remaining after the end of the TGA run was 50.41% as shown in Figure 3. This is quite close to the theoretical value of 48.98% for the conversion of magnesium ammonium phosphate hexahydrate to magnesium hydrogen phosphate (Frost et al., 2004). However, a temperature program of 1°/min is not representative of the heating conditions applied when heating batches of struvite for re-use. In this research, batches of struvite were isothermally heated in a pan in a thermostatted oven for 24 hours. The mass loss curves (calculated as percent mass remaining) for six different 24 hour isothermal treatments are also shown on Figure 3. A large gap exists between the mass remaining for the struvite that was isothermally heated at 80°C and 105°C, and the corresponding mass remaining 27  at these two temperatures on the TGA curve. The discrepancy is likely a result of the slow kinetics of thermal decomposition of struvite and is termed an “isothermal effect.” The temperature program in the TGA is too fast and does not give an accurate representation of the true thermodynamic decomposition temperature. In general, thermal decomposition depends on temperature, time, pan size and shape, and chemical makeup, as well as heat transport physics. With a perfectly designed oven and infinite heating duration, it is likely that the decomposition temperature for struvite falls in the range of 60-80°C. Wang et al. (2006) also find that the decomposition temperature lies between 60-100°C.  Percent mass remaining  100 90  TGA curve  80  Theoretical percent mass remaining 24 hour isothermal treatments  70 60 50 40 30 20 10 0 30  40  50  60  70  80  90 100 110 120 130 140 150 160 170 180 190 200 Heating temperature (°C)  Figure 3 Struvite TGA curve – Percent mass remaining versus temperature.  5.1.2 Mass gain versus time Heated struvite loses a large amount of water when heated and, therefore, has potential to gain mass when sitting on a table for a long period of time. Figure 4 shows the mass gain effect over a period of two weeks or greater sitting on a lab bench. The first point on each curve is the mass remaining immediately after being taken out of the oven. The 28  calculated mass increases are tabulated and range from 0-25% (Table 5). The two lowest heating temperatures show hardly any change in mass over time. However, between 80°C and 200°C, the mass recovery becomes much larger, reaching about 25%. The mass recovery is quite stable and does not seem to increase much further after approximately four days.  Calculations were also performed to determine the theoretical percent mass remaining in struvite for each additional water molecule that may become attached to an initially completely amorphous newberyite molecule (Table 6). This represents the possible “bulk sample” structural identity. The term “bulk sample” is defined as the average chemical composition of the sample. For the sample heated to 80°C, it appears that, immediately after heating, struvite has been converted to magnesium hydrogen phosphate monohydrate (MgHPO4●H2O) (Figure 4 and Table 6). After atmospheric exposure, it appears that the mineral identity reverts closer to newberyite (MgHPO4●3H2O) (Figure 4 and Table 6). The sample heated to 105°C appears to exist as MgHPO4●H2O immediately after heating, with conversion to MgHPO4●2H2O after two weeks. The samples heated to 160°C and 200°C appears to exist as amorphous newberyite (MgHPO4) immediately after heating with conversion to MgHPO4●2H2O after two weeks. These observed mass gains are hypothesized to be attributed to water absorption into the crystals, but were tested further using elemental analysis. In all cases the product was deduced based on mass only and represents a possible “bulk sample” identity. For example, it is likely that while sitting on the bench, some fraction of molecules become  29  trihydrated to the known mineral newberyite, while the other fraction does not. This leads to an average composition of a dihydrate, which may not actually exist in nature.  Percent mass remaining  100% 90% 40 80%  60  70%  80  60%  105 160  50%  200 40% 0  25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400  Theoretical  Time (hours) Figure 4 Percent struvite mass remaining over time for six different 24-hour heat treatments.  Table 5 Percent mass recovery after sitting on lab bench for two weeks.  Temperature 40 60 80 105 160 200  Percent mass recovery -0.7 1.1 13.3 18.0 25.3 25.4  Table 6 Theoretical bulk sample identity after exposure to atmospheric moisture.  Bulk Identity MgHPO4 MgHPO4●1H2O MgHPO4●2H2O MgHPO4●3H2O  Mass remaining 49% 56% 64% 71%  Two week water gain No water gain 1 water gain 2 water gain 3 water gain  5.1.3 Vacuum desiccation To prevent the heated pellets from absorbing atmospheric moisture, a vacuum desicator was tested for storage of some samples. The desicator used, however, was unable to 30  prevent a mass gain (Figure 5). The desicator did slightly reduce the equilibrium mass increase (1.4%) after 48 hours compared to the pellets being stored on the bench (1.7%). Since a better vacuum desicator was unable to be found, its use was abandoned as a method to control heated struvite mass gain over time.  26.8 26.6 26.4 mass (g)  26.2 26 25.8  mass in dessicator  25.6 25.4  mass when exposed to air  25.2 25 24.8 0  10  20  30  40  50  60  Time (hours) Figure 5 Struvite mass increase over time.  5.2 Elemental analysis Elemental Analysis of solid samples was conducted in order to supplement the results of the mass loss experiments. The accuracy of this technique allows for stronger evidence of heated struvite structural identity.  5.2.1 Ammonia content Elemental analysis results for nitrogen content in heated struvite pellets immediately after heating and after two weeks exposure to atmospheric moisture are shown in Figure 6. Excel solver was used to solve for ammonia content as shown in Appendix C. The lowest  31  temperature heat treatment does not show any difference in nitrogen content compared to the control sample (Ostara Crystal Green®). Beginning at a temperature of 60°C, the nitrogen content decreased to approximately 80%, and then drops significantly to about 30% when heated to between 80°C and 105°C. Heating at higher temperatures resulted in a drop in nitrogen content to between 13-19%. These results do not agree with Frost et al. (2004), likely because in this research isothermal heating was employed rather than a temperature program.  A paired two-tail t-test found no significant difference (p>0.05) in nitrogen content for samples taken immediately after heating compared to samples taken after two weeks of atmospheric exposure. This suggests that the crystals are not labile in terms of nitrogen release. These results are different than those found by Sugiyama et al. (2005), in which all ammonia was lost from struvite dust at 200°C. Perhaps, the interior of a pellet is not as accessible by the heat, and therefore, the bulk pellet contains a residual level of nitrogen.  1 0.9  Moles of nitrogen  0.8 0.7  Nitrogen content immediately after heat Nitrogen content after two weeks  0.6 0.5 0.4 0.3 0.2 0.1 0 Control  40  60 80 105 Heating temperature (°C)  160  200  Figure 6 Nitrogen content immediately after heating compared to after two weeks exposed to the atmosphere for six different temperatures and 24 hour duration.  32  5.2.2 Water content Elemental analysis was used to determine the hydrogen content in heated struvite pellets immediately after heating, and after two weeks exposure to atmospheric moisture (Figure 7). Similar to nitrogen, 40°C is not hot enough to cause decomposition. However, heating at 60°C causes the crystal to lose one water molecule. This result is inconsistent with mass loss data because one molecule of water theoretically accounts for 7.34% of total mass, but only 3.32% mass loss was observed. This may be explained by taking an elemental analysis sample from a non-homogeneous mixture of heated pellets. It is conceivable that in bulk heating, some portions of pellets are exposed to the heat more than others, resulting in a bulk heating mass loss lower than expected, if all portions of pellets were exposed equally. Heating at 80°C results in a loss of four additional (five total) water molecules. Above 80°C results in additional fractional water release. Approximately 0.18 water molecules remained after 200°C heating. These results do not confirm Sugiyama et al. (2009) who found that MgHPO4•3H20 is produced at heating temperatures of 60°C, or with Wang et al. (2006) who found that struvite is converted to amorphous newberyite at 100°C.. However, the results do confirm Sugiyama et al. (2005) who found that dittmarite is produced upon heating at 100-150°C.  In the range of 80-200°C it was observed that exposure to atmospheric moisture for two weeks resulted in an uptake of between 1.2-1.5 waters. However, as a percent increase, the water increase at each temperature was much different. For 80, 105, 160, and 200°C, the values are 130, 170, 480, and 720%, respectively, suggesting that struvite, heated at higher temperatures, has a greater affinity for atmospheric moisture after being taken out of the oven. 33  6  Moles of water  5 4  Water content immediately after heat  3  Water content after two weeks  2 1 0 Control  40  60  80 105 Heating temperature (°C)  160  200  Figure 7 Water content immediately after heating compared to after two weeks exposed to the atmosphere for six different temperatures and 24 hour duration.  5.2.3 Possible chemical identity The observed mass loss based on the weighing method, and calculated mass loss based on elemental analysis, is in close agreement and is shown in Table 7 and Table 8. A possible chemical formula of pellets heated at each temperature is also presented. The ammonia content is fairly stable across all samples, whereas the water content increases in the samples that were heated at temperatures at 60°C or above.  Table 7 Observed and calculated mass loss and possible chemical formula immediately after heating.  Temperature Room “control” 40 60 80 105 160 200  Observed loss N/A 0.4% 3.3% 39.5% 45.2% 49.3% 51.2%  Calculated loss 1.1% 1.5% 8.9% 41.7% 43.7% 47.4% 48.8%  Possible chemical formula MgHPO4(NH3)0.95(H2O)5.90 MgHPO4(NH3)0.96(H2O)5.84 MgHPO4(NH3)0.82(H2O)4.97 MgHPO4(NH3)0.28(H2O)1.00 MgHPO4(NH3)0.31(H2O)0.70 MgHPO4(NH3)0.19(H2O)0.31 MgHPO4(NH3)0.13(H2O)0.18  34  Table 8 Observed and calculated mass loss and possible chemical formula two weeks after heating and exposure to the atmosphere.  Temperature Room “control” 40 60 80 105 160 200  Observed loss N/A 0.7% 2.2% 31.4% 35.4% 36.5% 38.8%  Calculated loss 1.1% 2.8% 6.2% 32.3% 35.1% 36.6% 39.5%  Possible chemical formula MgHPO4(NH3)0.95(H2O)5.90 MgHPO4(NH3)0.90(H2O)5.71 MgHPO4(NH3)0.78(H2O)5.36 MgHPO4(NH3)0.26(H2O)2.30 MgHPO4(NH3)0.31(H2O)1.87 MgHPO4(NH3)0.16(H2O)1.80 MgHPO4(NH3)0.13(H2O)1.45  5.2.4 Environment effects on ammonia and water content The chemical composition of pellets placed in DI water for 5 minutes was tested using elemental analysis to see if any change occurs upon introduction of heated pellets into solution. Figure 8 shows that the ammonia content stays fairly stable upon placement in water except for the sample that had previously undergone isothermal heat treatment at 105°C. This may be due to the solubility of heated struvite. However, this effect was not observed at the other two temperatures.  0.35  Immediately after heat  Fractional moles of nitrogen  0.3  24 hours after heat  0.25  Rehydration after heat  0.2 0.15 0.1 0.05 0 80  105  160  Heating temperature (°C) Figure 8 Effect of heating temperature on struvite nitrogen content for three different environments.  35  The water content increases for all three temperatures when placed in DI water (Figure 9). This is expected as heated pellets are surrounded by water allowing for crystallization in areas of the crystal that was previously water deficient. The pellets probably do not reattain a molar water value of six because of the very short reaction period.  4 Immediately after heat  3.5  Moles of water  3  24 hours after heat  2.5 Rehydration after heat  2 1.5 1 0.5 0 80  105 Heating temperature (°C)  160  Figure 9 Effect of heating temperature on struvite water content for three different environments.  5.2.5 Comparing heated pellets to uptake pellets The three samples above were compared to a full batch of struvite (80g/L) that was rehydrated in DI water for 15 minutes, and a full batch of struvite (80g/L) that was placed in the synthetic ammonium solution at pH 8 for two hours. The ammonia content of the full batch of rehydrated struvite was slightly lower compared to struvite that has been heated only (Figure 10). This may be due to some dissolution of the pellet, releasing ammonium into solution. However, the pellets that were exposed to the synthetic ammonium solution resulted in a slight increase in nitrogen content. Dissolution of the pellets may be a source of magnesium and phosphate which can subsequently react with ammonium in the synthetic solution to reform new “fine” struvite that attaches to the 36  surface of the pellet. This mechanism, known as “dissolution-reformation (DR),” was also found by (Sugiyama et al., 2005).The validity of this hypothesis is supported by the  Fractional moles of nitrogen  nitrogen content in the fines that was close to the theoretical struvite value of one.  1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Immediately after heat  24 hours after heat  Rehydration after heat  Batch rehydration after heat  Uptake pH 8, Fines pH 8, 40g 40g  Figure 10 Effect of different environments on the nitrogen content in struvite heated at 105°C.  Approximately four moles of water exist in the structure of the rehydrated pellets and the “uptake” pellets (Figure 11). However, the fine crystals contain a water content of about 5.7 moles, which is closer to the theoretical pure struvite value. The “uptake” pellets and the fines both came from the same source of heated struvite and were subject to the exact same experimental conditions during the two hour exposure to synthetic ammonium solution. It is logical to assume that both solids had the same water content. Since this was not observed, the evidence in favour of a DR mechanism is strengthened.  37  6  Moles of water  5 4 3 2 1 0 Immediately after heat  24 hours after heat  Rehydration after heat  Batch rehydration after heat  Uptake pH 8, Fines pH 8, 40g 40g  Figure 11 Effect of different environments on the water content in struvite heated at 105°C.  All of the structures based on elemental analyses are compared in Table 9. It is most important to note that both the nitrogen and water content of pellets exposed to DI water and the pellets exposed to synthetic solution were very similar, whereas the fines have a chemical structure much closer to theoretical struvite.  Table 9 Structure comparison.  “Type” of struvite Heated struvite Heated struvite after 24 hours exposure Rehydration in DI H2O Uptake Fines  Possible chemical formula MgHPO4(NH3)0.31(H2O)0.70 MgHPO4(NH3)0.31(H2O)1.87 MgHPO4(NH3)0.26(H2O)4.12 MgHPO4(NH3)0.36(H2O)4.27 MgHPO4(NH3)0.90(H2O)5.67  5.3 Wet-chemical analysis – Molar ratios A small amount of heated struvite samples were dissolved and analyzed for the magnesium, nitrogen, and phosphorus concentrations. Molar ratios were calculated (N:P,  38  N:Mg, and Mg:P). Struvite immediately after 24 hour isothermal heating and for the same sample after being exposed to the atmosphere for two weeks was compared.  5.3.1 N:P ratio The N:P ratio was near unity up to 60°C (Figure 12). Between 80°C and 105°C, the N:P ratio drops to approximately 0.3 as ammonia is released from the crystal. Fumoto et al. (2009) also find that ammonia content drops to 0.3 when heated in an oven at 105°C. The N:P ratio decreased further to 0.22 and 0.16 for heating at 160°C and 200°C, respectively. The trend of results of these wet-chemical analyses is similar to the trend of the results using the elemental analysis method. However, at 160 and 200°C the elemental method yielded slightly smaller nitrogen contents compared to the N:P ratio calculated from wet-chemical analyses. For 60°C, the nitrogen content, using elemental analysis, was 0.15 moles less than the wet-chemical method. A plausible explanation may be that acid dissolution is unable to dissolve all of the phosphate in the pellets, leading to a N:P ratio that is biased high. This comparison is also complicated by the fact that absolute nitrogen content (elemental analysis) is being compared to relative nitrogen content (N:P ratio).  39  1.2  N:P ratio  1 0.8 0.6  Immediately after heating  0.4  After 2 weeks atmospheric exposure  0.2 0 40  60  80  105  160  200  Heating temperature (°C) Figure 12 N:P ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture.  5.3.2 N:Mg ratio Figure 13 shows the N:Mg ratio for the same set of samples. The same trend was observed as in the N:P ratio. This result is expected as both Mg is non-volatile.  1.2 1  N:Mg  0.8 0.6  Immediately after heating  0.4  After 2 weeks atmospheric exposure  0.2 0 40  60  80  105  160  200  Heating temperature (°C) Figure 13 N:Mg ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture.  40  5.3.3 Mg:P ratio Both magnesium and phosphorus don’t have a gaseous form and cannot escape the crystal when heated. Therefore, the Mg:P ratio was expected to be close to unity across all temperatures. The samples heated between 40°C to 105°C have the expected Mg:P ratio of 1 (Figure 14). The ratio observed at 160°C and 200°C was 1.2 and 1.45, respectively. This deviation was unexpected and suggests that a chemical conversion is occurring during thermal decomposition in this temperature range. Perhaps some phosphate is converted to pyrophosphate, which is much harder to dissolve in the acid used. Effectively, this reduces the amount of phosphorus that the analyzer can detect, resulting in an increased Mg:P ratio.  1.6 1.4 1.2  Mg:P  1 0.8  Immediately after heating  0.6  After 2 weeks atmospheric exposure  0.4 0.2 0 40  60  80 105 160 Heating temperature (°C)  200  Figure 14 Mg:P ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture.  5.4 Bulk sample heating Large samples of struvite (~120-150g) were isothermally heated for 24 hours in an aluminum pan. Percent remaining and molar ratios are calculated below. 41  5.4.1 Percent mass remaining In general, less mass remained as the temperature of isothermal heating increased (Figure 15). However, the trend is not followed for the 120°C, 180°C, and 200°C. Many experimental conditions were not controlled. These experiments were carried out over a two year period, using different pans and different ovens, which may explain some variation. Also, it is likely that the samples at 180°C and 200°C were able to absorb atmospheric moisture before the weight was recorded, causing a biased high result.  59  Percent mass remaining  58 57 56 55 54 53 52 51 50 80  100  105  120  140  160  180  200  Heating temperature (°C) Figure 15 Percent mass remaining after 24 hours heating.  5.4.2 Comparison of crushed and pelletized struvite from Lulu Island WWTP and Edmonton Alberta Gold Bar WWTP It was hypothesized that the surface area exposed to heat was a limiting factor in struvite mass loss and chemical transformation. For temperatures between 100°C -120°C, a comparison of the mass loss versus time for struvite in pellet form and crushed pellets indicates that surface area is not a key factor limiting the water and ammonia removal from a struvite crystal (Figure 16-18). This is surprising because thermal decomposition 42  is controlled by heat transfer, which increases as the surface area to volume gets larger. However, due to the long heating duration, heat transfer may no longer play an important role, resulting in near equal thermal decomposition profiles for different morphologies. This is further confirmed by the observation that the majority of mass loss occurred within the first hour of heating.  100 AB-100 whole AB-100 crushed AB-110 crushed AB-110 whole % theoretical remaining  90  % mass remaining  80 70 60 50 40 30 20 10 0 0  6  12  18  24  Heating time (hours)  % mass remaining  Figure 16 Percent mass remaining versus time comparing size and morphology at a heating temperature of 100°C.  AB-110 whole AB-110 crushed Lulu-110 whole Lulu-110 crushed  100 90 80 70 60 50 40 30 20 10 0 0  6  12 Heating time (hours)  18  24  Figure 17 Percent mass remaining versus time comparing size and morphology at a heating temperature of 110°C.  43  % mass remaining  AB-120 whole AB-120 crushed Lulu-120 whole Lulu-120 crushed  100 90 80 70 60 50 40 30 20 10 0 0  6  12 Heating time (hours)  18  24  Figure 18 Percent mass remaining versus time comparing size and morphology at a heating temperature of 120°C.  5.4.3 Time to achieve chemical transformation Separate struvite samples were heated at 30 minute intervals until three hours had elapsed and the remaining samples were heated at 60 minute intervals up to 6 hours. This procedure was carried out at four different temperatures ranging from 100°C to 140°C. The Mg:P ratios (Figure 19) were expected to remain unity as Mg and P are not non volatile. This was observed for the three lowest temperatures, but not for the highest temperature. This is likely due to the difficulty in dissolving phosphorus that may have been converted to pyrophosphate during heating at 140°C. The N:P ratio declined to 0.30.4 after 30 minutes of heating (Figure 20). The N:P ratio declined slightly further to 0.23-0.26 if the samples remained in the oven up to six hours. The same trend was observed in the N:Mg ratios (Figure 21). It appears that ammonia removal is largely complete after 30 minutes of heating at all temperatures. In comparison, Wang et al. (2006) found that heating longer than 2 hours is not cost effective to remove the  44  remainder of ammonia. This has important implications with respect to energy cost savings associated with heating struvite to remove ammonia.  1.40  100  1.20  110  Mg:P  1.00 0.80  120  0.60  140  0.40 0.20 0.00 0  1  2  3 4 Heating time (hours)  5  6  Figure 19 Mg:P vs. heating time for four temperatures.  N:P  100 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00  110 120 140  0  1  2  3 4 Heating time (hours)  5  6  Figure 20 N:P vs. heating time for four temperatures.  45  1.20  100  1.00  110  Mg:N  0.80 120  0.60  140  0.40 0.20 0.00 0  1  2  3 4 Heating time (hours)  5  6  Figure 21 N:Mg vs. heating time for four temperatures.  5.5 Uptake stage one: June 2009-October 2009 The first stage of struvite reformation experiments were conducted over a period of six months in 2009. Raw struvite from Edmonton, Alberta Gold Bar WWTP was isothermally heated at six temperatures (between 100°C-200°C) for 24 hours, to remove ammonia from the crystal. Struvite samples were subsequently placed in the synthetic ammonium feed at three different pH values (8, 9, and 10). These 24 combinations were used to determine the most effective heating temperature and solution pH to achieve maximum ammonium removal, while simultaneously maintaining pellet shape and strength. The struvite reformation reactions were completed over a period of 2 hours, with aqueous samples being taken every 15 minutes.  5.5.1 Ammonium profile The ammonia profile versus temperature of heating is discussed below. Experiments were conducted at three different constant pH values and compared. 46  5.5.1.1 Total ammonia concentration versus time at pH 8 The ammonia removals after 2 hours ranged from 91-98% (Figure 22). In general, ammonia removal was faster for struvite that was heated to higher temperatures. However, for struvite heated at 200°C, the trend was not followed. The relatively poor ammonia removal within the first 30 minutes may be explained by the greater solubility that the struvite has when heated at high temperatures. It is possible that the product is thermodynamically unstable and dissolves easily in water, releasing ammonium ions that were previously bound within the crystal. In general, a two hour reaction duration was required to reduce ammonia concentrations by 90% for struvite heated at low temperatures. The required reaction duration was only one hour for struvite heated at higher temperatures. This reduction in required reaction time is likely due to the higher solubility of struvite heated at higher temperatures. This means that struvite is a source of magnesium and phosphate and reacts with the excess ammonia, forming struvite more quickly.  350 300  Ammonia (mg/L)  250 Temp 100C  200  Temp 120C Temp 140C  150  Temp 160C  100  Temp 180C  50  Temp 200C  0 0  15  30  45 60 Time (Minutes)  75  90  105  120  Figure 22 Ammonia concentration for Gold Bar struvite at pH 8.  47  5.5.1.2 Total ammonia concentration versus time at pH 9 A similar total ammonia concentration versus time profile occurred for the samples that underwent the struvite reformation reaction at pH 9 (Figure 23). The major difference observed was the flatter shapes of the ammonia concentration versus time curves. At the 100°C heating temperature, only 48% ammonia was removed after two hours, whereas 97-99% was removed for the 140°C -180°C heating temperatures. Again, the sample heated to 200°C underperformed, likely as a result of high dissolution.  350 300  Ammonia (mg/L)  250  Temp 100C  200  Temp 120C  150  Temp 140C Temp 160C  100  Temp 180C  50  Temp 200C  0 0  15  30  45 60 75 Time (Minutes)  90  105  120  Figure 23 Ammonia concentration for Gold Bar struvite at pH 9.  5.5.1.3 Total ammonia concentration versus time at pH 10 Compared to the pH 9 profiles, the ammonia removals at pH 10 were worse (Figure 24). This is likely due to lower solubility of struvite at higher pH values, retarding the dissolution of the heated pellets, resulting in a lower source pool of magnesium and phosphate ions. The lowest ammonia removals occurred at 100°C and 200°C, with values of only 36% and 48%, respectively. The largest ammonia removals occurred at 140°C and 160°C at 73%. 48  350 300 Ammonia (mg/L)  250  Temp 100C  200  Temp 120C  150  Temp 140C Temp 160C  100  Temp 180C  50  Temp 200C  0 0  15  30  45  60  75  90  105  120  Time (Minutes) Figure 24 Ammonia concentration for Gold Bar struvite at pH 10.  5.5.1.4 Ammonia removal summary The results across all three pH conditions suggest that pH 8 is required to achieve the largest ammonia removals (91%-98%). This contradicts both Wang et al. (2006) and Sugiyama et al. (2009), who found that pH 10 results in the best ammonium removal due to a decrease in struvite solubility. If a two hour reaction duration is applied, the temperature that struvite was heated at becomes only a minor factor in ammonia removal. However, if heated at mid range temperatures (140°C -180°C) one hour reaction duration is sufficient. Higher heating temperature generally resulted in better ammonium removals, unlike Fumoto et al. (2009), who observed that higher heating temperature led to less adsorption sites. The ammonia removals are probably lower for reactions conducted at pH 9 and pH 10 because the solubility of struvite is reduced at higher pH values. This means that the fraction of struvite that remains in a heated crystal is thermodynamically stable and will not dissolve and act as a source of magnesium and phosphate, for nascent struvite formation. 49  5.5.2 Orthophosphate profile The orthophosphate profile versus temperature of heating is discussed below. Experiments were conducted at three different constant pH values and compared.  5.5.2.1 Orthophosphate concentration versus time at pH 8 The phosphate concentration profiles versus time were plotted at pH 8 for all six temperatures (Figure 25). At all temperatures, the concentration of phosphorus was found to increase over time. Dissolution is a time-dependent process and, therefore, the longer the pellets stay in solution the more they are able to dissolve, so that the solution can achieve saturation with respect to struvite. It was interesting to find that the lowest temperatures yield the smallest increase in phosphate concentrations. This result matches with the lowest ammonium removal (Figure 22). Also, the samples heated to 160°C and 200°C show the largest increase in phosphate concentrations, matched with the largest ammonium removals.  500 450 400 Phosphate (mg/L)  350  Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  300 250 200 150 100 50 0 0  15  30  45 60 75 Time (minutes)  90  105  120  Figure 25 Orthophosphate concentration for Gold Bar struvite at pH 8.  50  5.5.2.2 Orthophosphate concentration versus time at pH 9 The phosphate concentrations for reactions at pH 9 are lower than compared to pH 8 and do not show as much of a linear increase over time (Figure 26). This is due to the fact that struvite is less soluble at higher pH values. Similar to pH 8, the samples which had the largest phosphate concentrations also had the best ammonium removals. This suggests that heated struvite is a source of phosphate, which is subsequently utilized by excess  Phosphate (mg/L)  ammonium to form new struvite.  500 450 400 350 300 250 200 150 100 50 0  Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C 0  15  30  45  60  75  90  105  120  Time (minutes) Figure 26 Orthophosphate concentration for Gold Bar struvite at pH 9.  5.5.2.3 Orthophosphate concentration versus time at pH 10 The phosphate concentrations are stable for the duration of the reaction period at pH 10 (Figure 27). For the two highest temperatures, the phosphorus profile decreases versus time, because struvite is highly insoluble at this pH value.  51  Phosphate (mg/L)  500 450 400 350 300 250 200 150 100 50 0  Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C 0  15  30  45  60  75  90  105  120  Time (minutes) Figure 27 Orthophosphate concentration for Gold Bar struvite at pH 10.  5.5.2.4 Orthophosphate removal summary In general, phosphorus concentrations increase over time because the solution is undersaturated with respect to struvite; this caused the heated pellets to dissolve. This effect is known as “phosphate release” or “phosphate melting.” This process is time dependent and is amplified at lower pH values because heated struvite becomes more soluble. Phosphorus increased in solution by between 1050 to 1850% at pH 8, by 700 to 1900% at pH 9, and by -20 to 900% at pH 10.  It is apparent that a trade off between ammonium removal and phosphate release exists. To achieve the largest ammonium removals, one must be willing to release phosphate from the pellets back into solution. This melting process will be discussed further in the context of new, fine struvite formation.  52  5.5.3 Magnesium profile The magnesium profile versus temperature of heating is discussed below. Experiments were conducted at three different constant pH values and compared.  5.5.3.1 Total magnesium concentration versus time at pH 8 The magnesium concentration profiles versus time were plotted at pH 8 for all six temperatures (Figure 28). In general, magnesium concentration increased over time and was larger for struvite heated to higher temperatures. The concentration increase ranged from 70 to 2350%. Heated struvite pellets are a source of magnesium and the solubility increases with the degree of dehydration.  300.00 250.00  Maganisum (mg/L)  200.00 Temp 100C 150.00  Temp 120C Temp 140C  100.00  Temp 160C Temp 180C  50.00  Temp 200C 0.00 0  15  30  45 60 75 Time (minutes)  90  105  120  Figure 28 Magnesium concentration for Gold Bar struvite at pH 8.  5.5.3.2 Total magnesium concentration versus time at pH 9 The magnesium concentration profile at pH 9 showed smaller increases over time because the solubility of heated struvite is lower at higher pH (Figure 29). Magnesium is 53  not released from the pellets in large quantities like at pH 8. The percent increase in magnesium from solution ranged from -90 to 110%. This means that, in some experiments, magnesium was taken out of solution rather than being dissolved from the pellet source. These results correspond to the generally lower ammonium removals at pH 9, because of the smaller supply of available magnesium to form struvite.  80.00  Maganisum (mg/L)  70.00 60.00 50.00  Temp 100C  40.00  Temp 120C  30.00  Temp 140C Temp 160C  20.00  Temp 180C  10.00  Temp 200C  0.00 0  15  30  45 60 75 Time (minutes)  90  105  120  Figure 29 Magnesium concentration for Gold Bar struvite at pH 9.  5.5.3.3 Total magnesium concentration versus time at pH 10 Heated struvite pellets are most stable in the pH 10 solution. Magnesium release was minimal, ranging from -90 to 40% (Figure 30). Again, in some experiments, magnesium was taken out of solution rather than being added to solution from the pellet source. Since magnesium is not released in high quantities during pH 10 experiments, it makes sense that the least ammonium removals also occurred during the pH 10 experiments (Figure 24) as compared to the pH 8 experiments (Figure 22).  54  Maganisum (mg/L)  50.00 45.00 40.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00  Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C 0  15  30  45 60 75 Time (minutes)  90  105  120  Figure 30 Magnesium concentration for Gold Bar struvite at pH 10.  5.5.3.4 Total magnesium removal summary Lower pH causes heated struvite to become a source of magnesium in solution. This affect is amplified if the pellets were heated at temperatures 140°C and above. Below 140°C, the pellets are likely not dehydrated enough to allow for “melting.” Thus, a trade off also exists between ammonium removal and magnesium release. Ammonium cannot be effectively removed from solution without the pellets acting as a source of magnesium back to solution.  5.5.4 Solution supersaturation ratio (SSR) The SSR was calculated for each sample taken every 15 minutes using the Potts model. The variables measured were magnesium, phosphate, and ammonium concentrations, as well as temperature and conductivity. SSR is a measure of how much natural drive towards struvite crystallization exists in solution at any moment.  55  5.5.4.1 SSR at pH 8 The supersaturation ratios for experiments at pH 8 are shown in Figure 31. The four highest temperatures showed an initial increase in SSR followed by a subsequent decrease. This suggests that heated struvite dissolves at pH 8, releasing magnesium and phosphate into solution. This large molar source of magnesium and phosphate is likely the reason why ammonium reduction is so effective at pH 8. The two lowest temperatures do not show the same spike in SSR. This is likely because magnesium is not released from the pellets as shown in Figure 28, resulting is less ammonium removal. The SSR declined to a value below five, as the time reaches 120 minutes, suggesting that the struvite reaction is essentially complete.  45.0 40.0 35.0 30.0 100 120 140 160 180 200  SSR  25.0 20.0 15.0 10.0 5.0 0.0 0  20  40  60 80 Time (minutes)  100  120  140  Figure 31 SSR vs. time for various temperatures at pH 8.  5.5.4.2 SSR at pH 9 The SSR for experiments conducted at pH 9 is shown in Figure 32. Initially the SSR was high for all experiments, but then decreases over time. The SSR values are higher than for the corresponding experiments at pH 8. This means that more ions remain in solution 56  at pH 9. This is counter-intuitive, considering the previous argument that heated struvite is more soluble at lower pH values. Much more magnesium and phosphate are released back into solution at pH 8, compared to at pH 9. These ions quickly react with available ammonium to form struvite. This leaves excess magnesium and phosphate in solution but not ammonium, which leads to the decline in SSR. On the other hand, magnesium and phosphate are released more slowly and in smaller quantities at pH 9. Also, the releases are not necessarily stoiciometrically favourable for the formation of struvite and thus ammonium is removed less effectively from solution. Since all three components exist in solution in varying amounts, the SSR remains at a moderate level (SSR>10) for the majority of the experiments. 90.0 80.0 70.0 60.0  100 120 140 160 180 200  SSR  50.0 40.0 30.0 20.0 10.0 0.0 0  20  40  60 80 Time (minutes)  100  120  140  Figure 32 SSR vs. time for various temperatures at pH 9.  5.5.4.3 SSR at pH 10 The SSR for experiments conducted at pH 10 is shown in Figure 33. Here, the SSR values remain relatively large throughout the duration of all experiments. Heated struvite is even less soluble at pH 10, and not enough magnesium dissolves into solution to make 57  the formation of struvite as favourable as compared to pH 8. There is a large concentration of ammonium and phosphate that don’t have enough magnesium to form struvite, but still result in a relatively high SSR. Another possibility is that magnesium is released into solution in sufficient concentrations but is converted to an unavailable form of magnesium that is less reactive with ammonium and phosphate such as MgOH+, or Mg(OH)2.  120.0 100.0 80.0  100 120 140 160 180 200  SSR  60.0 40.0 20.0 0.0 0  20  40  60 80 Time (minutes)  100  120  140  Figure 33 SSR vs. time for various temperatures at pH 10.  5.5.5 Struvite fines production (dissolution-reformation validation) To quantitatively understand how well a heated pellet acts as a source of magnesium and phosphate, the fines were separated, dried on the lab bench, and weighed after the uptake reaction was completed. The samples at pH 8 produced a larger percentage of fines by weight, compared to pH 9 and pH 10 (Figure 34). The large release of phosphate (Figure 25) and magnesium (Figure 28) effectively removes ammonium from solution (Figure 22). The large SSR ratios at the beginning of the reaction confirms the large increase in phosphate and magnesium and also explains how 2-15% new fines (by total mass) are 58  formed, despite the feed solution being undersaturated with respect to struvite. The chemical identity of the fines is discussed in subsequent sections. It appears as though the trade off between ammonium removal and magnesium and phosphate release is validated. The unfortunate by product of ammonia removal, using heated struvite pellets, is a large percentage of fines formation. These fines are unwanted because they may clog up the struvite crystallizer. From an economical/marketing perspective, it is unsuitable to dissolve a valuable fertilizer pellet only to reform the same fertilizer, but in the form of a fine dust. However, for the purposes of ammonia removal alone, this may become a useful process.  18 16 14 % Fines produced  12 10 8 9 10  8 6 4 2 0 100  120  140  160  180  200  Heating temperature (°C) Figure 34 Percent fines produced versus isothermal heating temperature for pH 8, 9, and 10.  5.5.6 Caustic usage The amount of caustic used over time is shown for each temperature experiment over the three pH values (Figure35-37). It is seen that the amount of caustic use at the beginning is largest and minimal after the first 15 minutes. This is likely because most of the ammonia is removed from solution in the first 15 minutes. The pellet dissolves and becomes a 59  source of magnesium and phosphate and subsequently forms new struvite fines; this reduces the pH and requires an addition of caustic to maintain the pH set point.  30.0 25.0 100 120 140 160 180 200  mmol NaOH  20.0 15.0 10.0 5.0 0.0 0  20  40  60 Time (minutes)  80  100  120  Figure 35 Volume NaOH used vs. time for pH 8.  30.0 25.0  mmol NaOH  20.0 100 140 160 180 200  15.0 10.0 5.0 0.0 0  20  40  60 Time (minutes)  80  100  120  Figure 36 Volume NaOH used vs. time for pH 9.  60  30.0 25.0  mmol NaOH  20.0  100 120 140 160 180 200  15.0 10.0 5.0 0.0 0  20  40  60 Time (minutes)  80  100  120  Figure 37 Volume NaOH used vs. time for pH 10.  The total caustic use was recorded for each two hour ammonium removal experiment (Figure 38). Considering that the heated struvite is more soluble at lower pH and for pellets isothermally heated at higher temperatures, the caustic usage should be maximized. There is no clear trend in caustic usage. This is likely due to experimental error. Sometimes, caustic was added in quantities leading to a pH higher than the desired set point. Also, the volume added was determined by eye. A more rigorous record of caustic use is likely to result in an increase in caustic use at lower pH conditions, since heated struvite becomes a source of magnesium and phosphate which can react to form new struvite. When struvite forms, the pH is lowered, requiring an addition of caustic to maintain constant pH.  61  45 40 35  mmol NaOH  30 25  8 9 10  20 15 10 5 0 100  120  140 160 Temperature (°C)  180  200  Figure 38 Total mmol NaOH used versus temperature for 3 pH values.  5.5.7 Molar ratio comparison across solid products Heated struvite, uptake struvite, and fine struvite samples were dissolved in water and acid, and their contents analyzed. The three molar ratios were calculated for each of the heating temperature-pH experimental combinations. The purpose was to semiquantitatively determine the conditions producing the best ammonium removal.  5.5.7.1 N:P ratio comparison of roasted versus uptake versus fine struvite The N:P ratios calculated for each pH and heating temperature condition are shown in Figure 39-41. In general, the N:P ratio of roasted struvite declined with increasing temperature, as more ammonia is released from the crystal. Also, the N:P ratio increased slightly for most samples of uptake struvite compared to roasted struvite. This suggests that a fractional amount of ammonium is taken from solution and recovered into the pellet. The new fines formed possessed an N:P ratio that is closer to the characteristic  62  struvite ratio of 1:1. This suggests that fines formed are likely to be struvite, whereas uptake pellets are a mixture of magnesium phosphates, and possibly a thin struvite cover.  1.00 0.90 0.80 0.70 100 120 140 160 180 200  0.60  N:P  0.50 0.40 0.30 0.20 0.10 0.00 Roasted N:P  Uptake N:P  Fines N:P  Figure 39 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8.  1.00 0.90 0.80 0.70 100 120 140 160 180 200  0.60 N:P  0.50 0.40 0.30 0.20 0.10 0.00 Roasted N:P  Uptake N:P  Fines N:P  Figure 40 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9.  63  1.20 1.00 0.80  100 120 140 160 180 200  N:P  0.60 0.40 0.20 0.00 Roasted N:P  Uptake N:P  Fines N:P  Figure 41 N:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10.  5.5.7.2 N:Mg ratio comparison of roasted versus uptake versus fine struvite The N:Mg ratios calculated for each pH and heating temperature condition are shown in Figure 42-44. Similar trends to the N:P ratios are found because the nitrogen is compared to magnesium instead of phosphate, both of which are non-volatile.  1.20 1.00 0.80 100 120 140 160 180 200  N:Mg  0.60 0.40 0.20 0.00 Roasted N:Mg  Uptake N:Mg  Fines N:Mg  Figure 42 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8.  64  1.20 1.00 0.80  100 120 140 160 180 200  N:Mg  0.60 0.40 0.20 0.00 Roasted N:Mg  Uptake N:Mg  Fines N:Mg  Figure 43 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9.  1.4 1.2 1 100 120 140 160 180 200  N:Mg  0.8 0.6 0.4 0.2 0 Roasted N:Mg  Uptake N:Mg  Fines N:Mg  Figure 44 N:Mg ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10.  5.5.7.3 Mg:P ratio comparison of roasted versus uptake versus fine struvite The Mg:P ratios calculated for each pH and heating temperature condition are shown in Figure 45-47. Both magnesium and phosphorus are non-volatile at the heating temperatures applied during these experiments. It was expected that ratios for all experimental combinations would be close to the ideal 1:1. The ideal ratio was found to 65  be true, for fine struvite at all temperatures and pH conditions. However, an unexpected observation occurred for the heated and uptake samples. There was an upward trend towards an increasing Mg:P ratio with increasing heating temperature. This result confirms the more quantitative elemental analyses whose Mg:P ratios were 1.2 and1.5 for 160°C and 200°C, respectively (Figure 14).  1.60 1.40 1.20 1.00  100 120 140 160 180 200  Mg:P  0.80 0.60 0.40 0.20 0.00 Roasted Mg:P  Uptake Mg:P  Fines Mg:P  Figure 45 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 8.  1.40 1.20 1.00 100 120 140 160 180 200  Mg:P  0.80 0.60 0.40 0.20 0.00 Roasted Mg:P  Uptake Mg:P  Fines Mg:P  Figure 46 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 9.  66  1.60 1.40 1.20 1.00  100 120 140 160 180 200  Mg:P  0.80 0.60 0.40 0.20 0.00 Roasted Mg:P  Uptake Mg:P  Fines Mg:P  Figure 47 Mg:P ratios for roasted, uptake, and fine struvite. Six different roasting temperatures were used and all uptake experiments were conducted at pH 10.  5.5.8 Effect of temperature on molar ratios The temperature that pellets were roasted at was hypothesized to influence the molar ratios of the three solid products. The results were compared across three pH values. 5.5.8.1 Molar ratios versus temperature for constant pH 8 At constant pH 8 it was observed that both the roasted and uptake pellets exhibit a decrease in N:P and N:Mg ratio with increasing temperature (Figure 48-Figure 49). The fines have N:P and N:Mg ratios of about 1:1 indicating pure struvite. The Mg:P ratio in the fines is also indicative of struvite (Figure 50). However, the Mg:P ratio of the roasted and uptake pellets increases past unity above a heating temperature of 140°C. This result agrees with results from elemental analysis (Figure 14).  67  1.00 0.90 0.80 0.70 N:P ratio  0.60  Roasted N:P Uptake N:P Fines N:P  0.50 0.40 0.30 0.20 0.10 0.00 100  120  140  160 Temperature (°C)  180  200  220  Figure 48 N:P ratios versus temperature for pH 8.  1.20  N:Mg ratio  1.00 0.80 0.60  Roasted N:Mg  0.40  Uptake N:Mg Fines N:Mg  0.20 0.00 100  120  140  160  180  200  Temperature (°C) Figure 49 N:Mg ratios versus temperature for pH 8.  68  1.60 1.40  Mg:P ratio  1.20 1.00 0.80  Roasted Mg:P  0.60  Uptake Mg:P  0.40  Fines Mg:P  0.20 0.00 100  120  140  160  180  200  Temperature (°C) Figure 50 Mg:P ratios versus temperature for pH 8.  5.5.8.2 Molar ratios versus temperature for constant pH 9 Similar to pH 8, the N:P and N:Mg ratios of roasted and uptake struvite decline with increasing roasting temperature, and whereas the ratio in the fines is indicative of struvite (Figure 51-52). Again, the Mg:P ratio of roasted and uptake struvite becomes greater than  N:P raio  unity at heating temperatures greater than 140°C (Figure 53).  1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00  Roasted N:P Uptake N:P Fines N:P  100  120  140 160 Temperature (°C)  180  200  Figure 51 N:P ratios versus temperature for pH 9.  69  1.20 1.00  Mg:N ratio  0.80  Roasted Mg:N Uptake Mg:N Fines Mg:N  0.60 0.40 0.20 0.00 100  120  140 Temperature (°C)  160  180  200  Figure 52 N:Mg ratios versus temperature for pH 9.  1.40 1.20 1.00 Mg:P ratio  0.80 0.60  Roasted Mg:P  0.40  Uptake Mg:P  0.20  Fines Mg:P  0.00 100  120  140 160 Temperature (°C)  180  200  Figure 53 Mg:P ratios versus temperature for pH 9.  5.5.8.3 Molar ratios versus temperature for constant pH 10 Similar to pH 8 and 9, the N:P and N:Mg ratios of roasted and uptake struvite decline with increasing roasting temperature, and whereas the ratio in the fines is indicative of struvite (Figure 54-55). The Mg:P ratio of roasted and uptake struvite becomes does not  70  become greater than unity at heating temperatures greater than 140°C but still exhibits an increasing trend (Figure 56).  1.20  N:P ratio  1.00 0.80  Roasted N:P Uptake N:P Fines N:P  0.60 0.40 0.20 0.00 100  120  140  160 Temperatuer (°C)  180  200  Figure 54 N:P ratios versus temperature for pH 10.  1.4 1.2  N:Mg ratio  1 Roasted N:Mg Uptake N:Mg Fines N:Mg  0.8 0.6 0.4 0.2 0 100  120  140  160 Temperature (°C)  180  200  Figure 55 N:Mg ratios versus temperature for pH 10.  71  1.60 1.40 Mg:P ratio  1.20 1.00  Roasted Mg:P Uptake Mg:P Fines Mg:P  0.80 0.60 0.40 0.20 0.00 100  120  140  160 Temp erature(°C)  180  200  Figure 56 Mg:P ratios versus temperature for pH 10.  5.5.9 Effect of pH on molar ratios for constant temperatures The pH of the uptake reaction was hypothesized to influence the effectiveness of the desired uptake reaction. Molar ratios of the three solid products versus pH were calculated. For all six temperatures, the uptake N:Mg increases when the reaction takes place at pH 10 instead of pH 8 or 9 (Figure 57-Figure 62). However, the uptake N:P ratio does not have this same trend. This can be rationalized by the decrease in Mg:P ratio of both the roasted and uptake struvite when the reaction takes place at pH 10 instead of pH 8 or 9. Essentially, these results suggest that divalent magnesium ion becomes unavailable at higher pH values due to conversion into magnesium hydroxide species.  72  1.20 Roasted N:P  1.00  Molar ratio  Roasted Mg:P 0.80  Roasted N:Mg Uptake N:P  0.60  Uptake Mg:P 0.40  Uptake N:Mg Fines N:P  0.20  Fines Mg:P Fines N:Mg  0.00 pH 8  pH 9  pH 10  Figure 57 Solid product molar ratios vs. pH for a heating temperature of 100°C.  1.40 Roasted N:P  1.20  Roasted Mg:P  Molar ratios  1.00  Roasted N:Mg 0.80  Uptake N:P  0.60  Uptake Mg:P Uptake N:Mg  0.40  Fines N:P  0.20  Fines Mg:P  0.00  Fines N:Mg pH 8  pH 9  pH 10  Figure 58 Solid product molar ratios vs. pH for a heating temperature of 120°C.  73  1.40 Roasted N:P  1.20  Roasted Mg:P  Molar ratios  1.00  Roasted N:Mg 0.80  Uptake N:P  0.60  Uptake Mg:P Uptake N:Mg  0.40  Fines N:P  0.20  Fines Mg:P  0.00  Fines N:Mg pH 8  pH 9  pH 10  Figure 59 Solid product molar ratios vs. pH for a heating temperature of 140°C.  Molar ratios  1.60 1.40  Roasted N:P  1.20  Roasted Mg:P  1.00  Roasted N:Mg Uptake N:P  0.80  Uptake Mg:P 0.60  Uptake N:Mg  0.40  Fines N:P  0.20  Fines Mg:P  0.00  Fines N:Mg pH 8  pH 9  pH 10  Figure 60 Solid product molar ratios vs. pH for a heating temperature of 160°C.  74  1.40 Roasted N:P  1.20  Roasted Mg:P  Molar ratios  1.00  Roasted N:Mg 0.80  Uptake N:P  0.60  Uptake Mg:P Uptake N:Mg  0.40  Fines N:P  0.20  Fines Mg:P  0.00  Fines N:Mg pH 8  pH 9  pH 10  Figure 61 Solid product molar ratios vs. pH for a heating temperature of 180°C.  Molar ratios  1.60 1.40  Roasted N:P  1.20  Roasted Mg:P  1.00  Roasted N:Mg Uptake N:P  0.80  Uptake Mg:P 0.60  Uptake N:Mg  0.40  Fines N:P  0.20  Fines Mg:P  0.00  Fines N:Mg pH 8  pH 9  pH 10  Figure 62 Solid product molar ratios vs. pH for a heating temperature of 200°C.  5.5.10 Mass balance Mass balance calculations were conducted to quantitatively determine the sources, transfers, and sinks for the three species in struvite: Mg2+, NH4+, and PO43-. The masses of “heated struvite” were recorded before the uptake reaction. Struvite that remained on the 1mm, 500μm, and 250μm sieves were summed together and labelled as “total uptake 75  struvite”. Struvite that passed through the 250μm sieve was summed with struvite that remained on the filter paper and was labelled as “total fine struvite”. Mass balance data spreadsheets can be found in Appendix B.  5.5.10.1 N balance Bar graphs and a summary table illustrating the nitrogen balances for each experimental condition can be found in Appendix D. In most experiments, a nitrogen mass “imbalance” occurred. Nitrogen balance ranged from 88-181% of initial nitrogen. More nitrogen was calculated to be in the fines and uptake pellets than was available (ie. the mass of nitrogen removed from solution). This is likely due to experimental error. Care must be taken to control the water content in the particular components. The mass calculations are based on converting a solution concentration into a mass. The total mass of heated pellets was only recorded initially after being taken out of the oven, but not when the sub sample from these pellets were dissolved for analysis. During this time, atmospheric water absorbs onto a heated pellet, as shown in Figure 7, Figure 9, and Figure 11.  5.5.10.2 P balance Bar graphs and a summary table illustrating the phosphorus balances for each experimental condition can be found in Appendix D. Phosphorus mass “imbalances” were calculated for most experiments; this was caused by the absorption of water on the heated pellets during the time between taken out of the oven and when the samples were actually analyzed. The imbalances ranged from 89-131% of initial phosphorus.  76  5.5.10.3 Mg balance Bar graphs and a summary table illustrating the magnesium balances for each experimental condition can be found in Appendix D. Magnesium mass “imbalances” were also calculated for most experiments, ranging from 61-157%. The likely cause was also the absorption of water on the heated pellets during the time between taken out of the oven and when the samples were actually analyzed. 5.5.10.4 Summary of mass balance results The mass “imbalances” are likely largely attributed to mass losses during transfer from the oven to the balance, and from the reactor to the weigh dish. Two other large sources of error include the fact that struvite is hygroscopic after heating, and the long duration (up to 5 days) needed for drying to an equilibrium temperature.  5.6 Uptake stage two: May 2010-August 2010 The second stage of struvite reformation experiments were conducted over a period of four months in 2010. Raw struvite from the Gold Bar WWTP was isothermally heated at three temperatures (80°C, 105°C, and 160°C) for 24 hours. Only three temperatures were selected at this stage, so that a comparison could be made between low, medium, and high temperature heating on ammonium removal. Also, only two different pH conditions were applied (pH 8 and pH 9) because it was concluded in Stage one that ammonium removal was unsatisfactory at pH 10. To obtain an estimate of the required amount of sorbent required, heated struvite was added in either 20g (40g/L) or 40g (80g/L) batches. The struvite reformation reactions were completed over a period of 2 hours, with aqueous samples being drawn from the reactor every 15 minutes.  77  5.6.1 Uptake experiments at constant pH 8 The three components of struvite were sampled every 15 minutes and stored for later analysis. The pH was maintained at constant pH 8 for the duration of uptake.  5.6.1.1 Total ammonia concentration versus time at constant pH 8 All experiments show decreasing ammonium concentrations versus time (Figure 63). In general, ammonium removal was better when the sorbent was heated at higher temperatures, and when sorbent addition was largest (Sugiyama et al., 2009). The best  Concentration NH4+ (mg/L)  removal occurred for 40g sorbent heated to 160°C.  750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0  105°C, 20g, 2hr 105°C, 20g, 2hr 105°C, 20g, 2hr 105°C, 40g, 2hr 160°C, 20g, 2hr 160°C, 40g, 2hr 80°C, 20g, 2hr 80°C, 20g, 2hr 0  15  30  45  60 75 Time (minutes)  90  105  120  80°C, 40g, 2hr  Figure 63 NH4+ concentration vs time at pH 8.  5.6.1.2 Ortho-phosphate concentration versus time at constant pH 8 All experiments show an increase in phosphate concentrations over time (Figure 64). The dissolution of phosphate from the pellets was higher for larger sorbent dosages, and for higher temperatures of heating. Almost the same amount of phosphate was released for both the 105°C and 160°C temperatures, with a sorbent dosage of 40g. This suggests that 78  105°C is the approximate threshold heating temperature that alters the crystal enough to cause significant “melting.” Since the ammonium removal was lower at 105°C, compared with 160°C, but the “melting” was the same, it is recommended that the pellets should be  Concentration PO43- (mg/L)  heated to 160°C, in order to maximize ammonium removal.  240 220 200 180 160 140 120 100 80 60 40 20 0  105°C, 20g, 2hr 105°C, 20g, 2hr 105°C, 20g, 2hr 105°C, 40g, 2hr 160°C, 20g, 2hr 160°C, 40g, 2hr 80°C, 20g, 2hr 80°C, 20g, 2hr 80°C, 40g, 2hr  0  15  30  45  60 75 Time (minutes)  90  105  120  Figure 64 PO43- concentration vs. time at pH 8.  5.6.1.3 Magnesium concentration versus time at constant pH 8 The magnesium concentration profile over time is shown for uptake experiments at constant pH 8 (Figure 65). The magnesium was released in large amounts only when heated at 160°C for both dosages. This seems to contradict the above argument regarding phosphate release. Perhaps the release of magnesium and phosphate is a function of heating temperature, sorbent quantity, as well as solubility conditions. This means that the reaction solutions are undersaturated with respect to phosphate and, thus, the largest sorbent quantity (80g/L) can supply enough through dissolution. On the other hand, magnesium may not be as undersaturated as phosphate is. Instead, the pellet became  79  soluble when heated to 160°C, regardless of sorbent quantity and may, in fact, cause supersaturation with respect to magnesium.  Concentration Mg2+ (mg/L)  200 180  105°C, 20g, 2hr  160  105°C, 20g, 2hr  140  105°C, 20g, 2hr  120 105°C, 40g, 2hr  100 80  160°C, 20g, 2hr  60  160°C, 40g, 2hr  40  80°C, 20g, 2hr  20  80°C, 20g, 2hr  0 0  15  30  45  60 75 Time (minutes)  90  105  120  80°C, 40g, 2hr  Figure 65 Mg2+ concentration vs. time at pH 8.  5.6.2 Uptake experiments at initial pH 8 with no control An experiment was conducted to characterize the effectiveness of the uptake reaction when pH was initially set to 8, but not controlled thereafter. Results were compared to constant pH experiments. 5.6.2.1 Total ammonia concentration versus time at initial pH 8 The ammonium removal, when the pH was not controlled, was very poor (Figure 66). After the two hour reaction period, the solids were separated and the pH of the filtrate was increased to approximately pH 9-10. The ammonium removal achieved was the same as in the experiment at 160°C, with 80g/L of sorbent. This experiment shows that the pellets must be dissolving when the pH declines; leaving a source of magnesium and phosphate in solution that is subsequently removed when caustic is added to the filtrate. 80  In effect, controlling the pH may not be the best way to recycle struvite for ammonium removal. This contradicts Sugiyama et al. (2006) who found that ammonia removal increases when the pH is not controlled and allowed to decline from 8 to 6 over the duration of the reaction.  700 Concentration NH4+ (mg/L)  600  160°C, 20g, 2hr  500  160°C, 40g, 2hr  400 300  160°C, 20g, 2hr, no pH control  200 100 0 0  15  30  45 60 75 Time (minutes)  90  105  120  160°C, 20g filtrate, 30 min  Figure 66 Effect of no pH control on NH4+ concentration.  5.6.2.2 Orthophosphate concentration versus time at initial pH 8 The pellets were confirmed to dissolve when the pH was not controlled (Figure 67). The two middle curves are data already shown in Figure 64 and are comparatively lower despite, being the previously largest phosphate release curves. Uncontrolled pH uptake reactions release large quantities of phosphate into solution because heated struvite is more soluble at more acidic pH. When the pH of the filtrate was increased, the phosphate immediately declined to approximately 20 mg/L, which is close to the initial value. This method is as effective at preventing phosphate from leaving the reactor as the experiments conducted at 80°C (Figure 64), with the added benefit of maximal ammonium removal. 81  700 160°C, 20g, 2hr  Concentration PO43- (mg/L)  600 500  160°C, 40g, 2hr  400  200  160°C, 20g, 2hr, no pH control  100  160°C, 20g filtrate, 30 min  300  0 0  15  30  45  60 75 Time (minutes)  90  105  120  Figure 67 Effect of no pH control on PO43- concentration.  5.6.2.3 Magnesium concentration versus time at initial pH 8 The uncontrolled pH also released substantially more magnesium compared to the controlled experiments (Figure 68). When the pH of the filtrate was raised, the magnesium immediately decreased down to 10 mg/L, which is close to the initial concentration.  600  Concentration Mg2+ (mg/L)  500 160°C, 20g, 2hr  400 300  160°C, 40g, 2hr  200  160°C, 20g, 2hr, no pH control  100  160°C, 20g filtrate, 30 min  0 0  15  30  45  60 75 Time (minutes)  90  105  120  Figure 68 Effect of no pH control on Mg2+ concentration.  82  5.6.3 Uptake experiments at constant pH 9 Uptake experiments were conducted at a constant pH 9 and the three struvite components were sampled from solution every 15 minutes, over a reaction period of two hours. A comparison was made for different masses of sorbent added, and for different temperatures that the struvite was heated at.  5.6.3.1 Total ammonia concentration versus time at constant pH 9 The ammonia removal was greater for the larger sorbent additions (Figure 69). However, the ammonia removal was very poor compared to the corresponding experiments conducted at constant pH 8 (Figure 63). It appears as though increasing the pH reduces the viability of the ammonia recovery, using heated struvite.  900  80°C, 20g, 2hr  800 Concentration NH4+ (mg/L)  700  80°C, 40g, 2hr  600 160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr  500 400 300 200  105°C, 20g, 2hr  100 0 0  15  30  45  60  75  90  105  120  105°C, 40g, 2hr  Time (minutes) Figure 69 NH4+ concentration vs. time at pH 9.  83  5.6.3.2 Orthophosphate concentration versus time at constant pH 9 Orthophosphate concentrations versus time did not show a large change when the experiment was conducted at constant pH 9 (Figure 70). This is much different than at constant pH 8 (Figure 64), which showed that phosphate was released into solution in large quantities.  20 18 Concentration PO43- (mg/L)  16  80°C, 20g, 2hr  14 12  80°C, 40g, 2hr  10 8  160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr  6 4 2 0 0  15  30  45  60 75 Time (minutes)  90  105  120  Figure 70 PO43- concentration vs. time at pH 9.  5.6.3.3 Magnesium concentration versus time at constant pH 9 Magnesium concentrations increased for only the 160°C roasting temperatures, and decreased for all other experiments (Figure 71). This is similar to the result found at pH 8 (Figure 65). This means that at pH 9 the solutions may still be undersaturated with respect to magnesium, but not with respect to phosphate.  84  50  Concentration Mg2+ (mg/L)  45 40  80°C, 20g, 2hr  35 30  80°C, 40g, 2hr  25 20  160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr  15 10 5 0 0  15  30  45  60  75  90  105  120  Time (minutes) 2+  Figure 71 Mg concentration vs. time at pH 9.  5.6.4 Molar ratios Solid samples of roasted struvite, struvite after uptake, and fine struvite after uptake were dissolved with HCl and the concentrations of magnesium, ammonium, and phosphate were analyzed. Molar ratios were calculated for each experiment.  5.6.4.1 N:P ratios at pH 8 At pH 8, the N:P ratios for roasted struvite and struvite after uptake were in close agreement, except for one experiment (Figure 72). This suggests that ammonium does not become incorporated into the heated struvite crystal during the uptake reaction. The N:P ratio of uptake struvite in experiment nine was probably larger than the roasted struvite because the pH was not controlled in this experiment; this may have caused fine struvite to form and bond to the surface of the intact pellet. This is different than fines formed in solution, which are completely detached from the intact struvite pellets. Struvite fines that appear during the uptake reaction had an N:P ratio much closer to unity, suggesting that  85  struvite is the likely identity. The fines for the fifth experiment did not show the characteristic struvite N:P ratio. This is explainable because these pellets were only subjected to DI water in order to rehydrate the pellet and did not have access to external sources of ammonia. These fines may simply be fine fragments that broke away from the pellet during mixing, rather than newly formed fine struvite.  1.20 1.00 N:P ratio  0.80 0.60 0.40 0.20 0.00  roasted uptake fines  Figure 72 Solid product N:P ratios for uptake experiments at pH 8.  5.6.4.2 N:Mg ratios at pH 8 The N:Mg ratios at pH 8 followed nearly the same trends as the N:P ratios (Figure 73). These results suggest that classic struvite is not reformed in the intact pellets. Newly formed fines are probably closer in identity to pure struvite.  86  1.20 1.00 N:Mg ratio  0.80 0.60 0.40 0.20  roasted uptake fines  0.00  Figure 73 Solid product N:Mg ratios for uptake experiments at pH 8.  5.6.4.3 Mg:P ratios at pH 8 Theoretically, the Mg:P ratio should remain unchanged with a value of 1:1 for all three solid phases. This hypothesis was confirmed, because the Mg:P ratios for all twelve experiments are similar (within expected experimental errors) for the three solid phases  Mg:P ratio  (Figure 74). 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00  roasted uptake fines  Figure 74 Solid product Mg:P ratios for uptake experiments at pH 8.  87  5.6.4.4 N:P ratios at pH 9 The N:P ratios were calculated for nine experiments done at constant pH 9 (Figure 75). The roasted and uptake samples generally had the same ratios, whereas the fines had a much higher ratio. These results agree with Stage one: 2009 results. 1.00 0.90 0.80 0.70 N:P ratio  0.60 roasted uptake fines  0.50 0.40 0.30 0.20 0.10 0.00 80°C, 20g  80°C, 40g  160°C, 20g  160°C, 40g  105°C, 20g  105°C, 40g  Figure 75 Solid product N:P ratios for uptake experiments at pH 9.  5.6.4.5 N:Mg ratios at pH 9 The N:Mg ratios at pH 9 followed nearly the same trends as the N:P ratios (Figure 76). In most instances, the roasted and uptake samples had very close to the same ratios. The fines usually had N:Mg ratios greater than 0.8, indicative of struvite formation, albeit impure.  88  1.20 1.00  N:Mg  0.80 roasted uptake fines  0.60 0.40 0.20 0.00 80°C, 20g  80°C, 40g  160°C, 20g 160°C, 40g 105°C, 20g 105°C, 40g  Figure 76 Solid product N:Mg ratios for uptake experiments at pH 9.  5.6.4.6 Mg:P ratios at pH 9 Mg:P ratios for the nine experiments conducted at pH 9 is shown in Figure 77. As expected, the characteristic struvite ratio was found for most samples. One samples has a large Mg:P ratio, likely as a result of an analysis error in magnesium or phosphate concentration.  1.80 1.60 1.40 Mg:P ratio  1.20 1.00  roasted uptake fines  0.80 0.60 0.40 0.20 0.00 80°C, 20g  80°C, 40g  160°C, 20g 160°C, 40g 105°C, 20g 105°C, 40g  Figure 77 Solid product Mg:P ratios for uptake experiments at pH 9.  89  5.6.5 Full dissolution followed by reformation In five experiments, the heated struvite was completely dissolved in acid to pH <2, containing 500 ml of feed solution. All residual ammonia in the pellets was released, as well as magnesium and phosphate. This solution was then increased up to pH 9-10 so that struvite could be crystallized again. These five experiments are hypothesized to follow the DR mechanism. The N:P ratio of the fines formed in these experiments was lower than expected (0.4-0.5) (Figure 78). The concentration of caustic used was quite high (6M) and likely increased the pH much past 9 in concentrated zones, in which other insoluble magnesium phosphates are formed, before struvite. It is also possible that during the quick increase of pH, the highly concentrated aqueous ammonia was able to escape into the atmosphere.  1.20 1.00  Molar ratios  0.80 0.60 N:P Mg:P  0.40  N:Mg 0.20 0.00 105°C, 10g  160°C, 5.7g  80°C, 20g  160°C, 20g  105°C, 20g  Figure 78 Effect of complete dissolution using acid prior to struvite crystallization for different heating temperatures and sample sizes.  Nitrogen mass balances were calculated for all samples and are shown in Figure 79-83. Since no pellets were formed, the ammonia in the feed was incorporated into newly 90  formed fine struvite. The nitrogen mass remained slightly imbalanced for all experiments (87-127%), despite the lack of pellets which are known to adsorb water. Four of the five experiments had a reduction in mass, as expected, due to ammonia evaporation. One of the five experiments had a gain in mass, which may have occurred if the fines were not  mg N  completely dry.  800 700 600 500 400 300 200 100 0  before after  Feed  Fines  Total  N sink  mg N  Figure 79 Nitrogen balance for 10g complete dissolution and reformation for a heating temperature of 105°C.  500 450 400 350 300 250 200 150 100 50 0  before after  Feed  Fines N sink  Total  Figure 80 Nitrogen balance for 5.7g complete dissolution and reformation for a heating temperature of 160°C.  91  mg N  1000 900 800 700 600 500 400 300 200 100 0  before after  Feed  Fines N Sink  Total  mg N  Figure 81 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 80°C.  1000 900 800 700 600 500 400 300 200 100 0  before after  Feed  Fines  Total  N sink Figure 82 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 160°C.  92  1200 1000 mg N  800 before  600  after  400 200 0 Feed  Fines  Total  N sink Figure 83 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 105°C.  5.7 Mass balance The mass balances for nitrogen, phosphorus, and magnesium for 2009 experiments, ranged from 75-122%, 63-202%, and 67-191%, respectively as shown in the source and sink budgets in Appendix D. There is no clear trend showing the flow of the different components between sources and sinks, despite the evidence based on molar ratios in favour of a DR mechanism. 5.8 Specific uptake The specific uptake was calculated for each experimental condition and shown in Figure 84-86. There are no clear trends. It looks as though the specific uptake decreases as the temperature of heating increases, although this result needs to be replicated in order to be valid. It also appears that pH 9 may have a higher specific uptake compared to pH 8 (which dissolves struvite too much) and pH 10 (which does not dissolve struvite to provide enough source ions). Stefanowicz et al. (1992) achieved a much higher specific ammonia removal rate at approximately 71.4 mg N/ g roast product. 93  Specific uptake (mg N uptake/g heated struvite)  10.0 8.0 6.0 4.0 pH 8 2.0  pH 9  0.0 -2.0  pH 10 100  120  140  160  180  200  -4.0 -6.0  Heating temperature (°C)  Figure 84 2009 specific uptake versus heating temperature for three pH values.  Specific uptake (mg N per g of heated struvite)  5 4 3 2 1  Constant pH, 20g  0  no pH control, 20g  -1  80  105  160  Constant pH, 40g  -2 -3 -4  Heating temperature (°C)  Figure 85 2010 specific uptake versus heating temperature at pH 8.  94  Specific uptake (mg N per g of heated struvite)  12.0 10.0 8.0 6.0 Constant pH, 20g  4.0  Constant pH, 40g  2.0 0.0 -2.0 -4.0  80  105  160  Heating temperature (°C)  Figure 86 2010 specific uptake versus heating temperature at pH 9.  5.9 SEM results The inside of a raw Gold Bar struvite pellet is shown in Figure 87 and Figure 89. A distinct “onion” layering is observed, due to the nature of formation of crystal aggregation in the fluidized bed reactor. Heating the pellet causes cracks along the surface of the layers as the bulk structure weakens, releasing water and ammonia (Figure 88). At 500 times magnification, the raw struvite is seen to have a generally smooth surface (Figure 90), whereas the roasted struvite has a much rougher “needle-like” surface due to the extensive fracturing (Figure 91). For an uptake pH of both 8.5 and 10.5, the pellet morphology is observed to have a “dulling” characteristic (Figure 92-95). The cracked structures still exist, but the needle-like crystals are replaced by a more rounded globular formation. This may be the result of dissolution of the needle-like magnesium hydrogen phosphate crystals with subsequent struvite reformation to fill in the crevices.  95  Figure 87 Raw Gold Bar struvite interior 35x.  Figure 90 Raw Gold Bar Struvite cut 500x interior.  Figure 88 Heated Gold Bar struvite interior 70x.  Figure 91 Heated Gold Bar struvite 500x interior.  Figure 89 Raw Gold Bar struvite interior 70x.  Figure 92 Uptake pH 8.5 cut 500x interior.  96  Figure 93 Uptake pH 8.5 cut 40x.  Figure 94 Uptake pH 10.5 cut 40x.  Figure 95 Uptake pH 10.5 cut 500x interior.  5.10 Preliminary economic analysis A preliminary economic analysis was conducted to determine the possible costs involved with this ammonia recovery approach. The four major costs involved are for purchasing raw struvite, caustic, electricity, and labour. It is assumed that the cost of purchasing raw struvite is $3000/tonne. Also, to determine the amount of centrate produced per year, the average 2009 flow and BOD removals at Lulu Island WWTP were retrieved and used from Metro Vancouver, with values of 76.2 MLD and 550lb/ML, respectively. Other assumptions include the sludge specific gravity equal to 1.02 (Viessman & Hammer, 97  2004), BOD utilization rate of 0.05 lb cells/lb BOD utilized (Viessman & Hammer, 2004), 0.5% of influent flow becoming sludge flow (Constantine, 2006), and 75% of sludge flow becoming centrate flow (Viessman & Hammer, 2004). The caustic price is assumed to be $500/tonne. The electricity price is assumed to be $0.02817/kwh as per BC Hydro’s business rates. The mixer is assumed to have an efficiency of 90%. Labour costs are assumed to be $120/day (Britton et al., 2005). The cost summary to treat this volume of wastewater (with Lulu Island WWTP characteristics) is shown in Table 10. The largest cost is for purchasing the raw struvite because it is a very valuable commodity. However, if prices fluctuate and moved downward, this cost might be reduced. The detailed spreadsheet calculations are shown in Appendix E. Table 10 Economic analysis.  Price component Struvite Caustic Electricity Labour Total  Cost per day ($/day) 8670 805 217 120 9812  For a valid economic analysis, this technique must be compared to an alternative, such as side stream biological nitrification. Right now in Metro Vancouver, ammonia discharge concentrations are not enforced because it is deemed that ammonia toxicity is not a high priority issue. However, facilities such as the Hyperion Waste Water Treatment Plant in Los Angeles, California, nitrify the digester supernatant and centrate in order to prevent ammonia toxicity in Santa Monica Bay. Therefore, an approach assuming Lulu Island WWTP will also one day side stream nitrify the digester centrate has been selected. To reduce the ammonia from 700mg/L to the EPA guideline of 5mg/L with the Lulu Island WWTP flows it would require about 1620 kg/day of oxygen. At a cost of $0.2/kg O2, the 98  daily oxygen cost would be about $320. Assuming the wastewater contains 100mg/L alkalinity as CaCO3, the amount which must be replaced, is approximately 1113 kg/day of CaCO3. This cost would sum to $334 per day, assuming a price of $0.3/kg CaCO3. Thus, the total daily cost to nitrify the centrate to non toxic concentrations, would be about $650. Therefore, the preliminary economic analysis has found that conventional side stream nitrification of anaerobic centrate is about 15 times cheaper per day. This analysis depends on the assumption that ammonia toxicity is an issue to be addressed. Of course if ammonia toxicity is not a problem, then both of these processes should not be implemented, solely based on cost.  99  6 Conclusions The results of the preliminary bench-scale research on ammonia removal and recovery, using heated struvite as an adsorbent, yielded the following conclusions:  The 24-hour isothermal decomposition temperature of struvite at atmospheric pressure and moisture conditions was between 60-80°C. Struvite is not completely decomposed to amorphous newberyite because the N:P ratios remain at 0.2-0.3. The product is likely a mixture of magnesium phosphates. Higher heating temperature caused both the amount of ammonia and water released to be increased. Only 0.5-1 hour was necessary at 100-200°C to decompose struvite and remove about 70% of nitrogen. Sample surface area or sample location source did not seem to have an effect on the heating of a bulk struvite sample. The environment and duration have a large effect on the amount of water readsorbed onto the crystal after heating. Vacuum desiccation at 17in Hg was not sufficient to prevent this effect. Higher heating temperatures had proportionally higher water adsorption rates, on decomposed pellets. A trade off exists; ammonia removal can be achieved, up to 99%, using heated struvite as an adsorbent, which must first dissolve, ruining the marketable pellet form. 100  Phosphate and magnesium are released from the pellet form into solution, due to the high solubility of heated struvite. The molar ratios data revealed that only newly-formed fines were struvite whereas the pellet struvite was a mixture of different magnesium phosphates. Newly formed fines possess molar ratios characteristic of pure struvite. Pellets did not possess molar ratios characteristic of pure struvite after the uptake reaction. The molar ratios resembled heated struvite pellets. Pellets showed a small fractional increase in nitrogen content, due to surface adsorption by fines. If a different technology could make use of struvite as an adsorbent of ammonia nitrogen, without any material losses, then this technology might be more cost effective at full scale compared to conventional side stream nitrification.  101  7 Recommendations Based on the results of the bench scale experiments on ammonia removal and recovery using struvite as an adsorbent, the following recommendations are proposed:  XRD analyses should be conducted in order to construct phase diagrams after heating struvite. Real-time TGA-MS or TGA-IR analyses run to precisely determine if water and ammonia are evolved at the same temperature and time. Use a better vacuum desiccation system to control atmospheric moisture from adsorbing or absorbing onto struvite pellets Determine if struvite can be decomposed into newberyite at high vacuum, at room temperature. Do more elemental analyses between 60-80°C, to probe closer to the true decomposition temperature. An elemental analysis should be run on a sample that is rehydrated for longer than 5 minutes, after heating, to allow for a longer time for water to access the whole pellet and potentially regain hexahydration. Determine the identity of the product after heating at 160°C and above, to determine the source of the Mg:P ratio between 1.2-1.5. The viability of collecting the evolved ammonia, using a resin or boric acid or by a common fertilizer method, should be investigated.  102  The effects of scaling up to pilot scale should be determined to check what happens to attrition rates, ammonium removals, and phosphate and magnesium release into solution. More rigorous and controlled experimental conditions must be maintained from heating through to uptake, in order to properly mass balance the three components that make up struvite. 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W., & Gurney, E. L. (1963). Solubility products of magnesium ammonium and magnesium potassium phosphates. Transactions of the Faraday Society , 59, 1580-1584. Turker, M., & Celen, I. (2007). Removal of ammonia as struvite from anaerobic digester effluents and recycling of magnesium and phosphate. Bioresource Technology , 98, 1529–1534. Ueno, Y., & Fujii, M. (2001). Three years experience of operating and selling recovered struvite from full-scale plant. Environ. Technol. , 22, 1373-1381. Viessman, W. J., & Hammer, M. J. (2004). Water Supply and Pollution Control. Prentice Hall. Wang, L., Sun, T., & Zhang, Y. (2006). Preparation of sorbent from magnesium ammonium phoshpate for adsorption of ammonia nitrogen in wastewater. Sciencepaper Online , 1-7. Woods, N. C., Sock, S. M., & Daigger, G. T. (1999). Phosphorus recovery technology modeling and feasibility evaluation for municipal wastewater treatment plants. Environmental Technology , 20, 663-679. Yariv, S., Muller-Vonmoos, M., Kahr, G., & Rub, A. (1989). Thermal analytic study of the adsorption of acridine organge by smectite minerals. 35, 1997-2008. Zhang, S., Yao, C., Feng, X., & Yang, M. (2004). Repeated use of MgNH4PO4.6H20 residuesfor ammonium removal by acid dipping. Desalination , 170, 27-32.  106  Appendix A: Instrument operational parameters Table A. 1 Magnesium AA operating parameters  Species Analyzed Concentration Units Instrument mode Sampling mode Calibration mode Measurement mode Replicates standard Replicates sample Wavelength Range  Magnesium2+ Mg mg/L Absorbance Autonormal Concentration Integrate 3 3 202.6 nm 0-100 mg/L  Flame type Calibration algorithm Lamp current  N2O/C2H2 New rational 4.0 mA  Table A. 2 Lachat parameters for ammonia and phosphate  Species Analyzed Concentration Units Range Temperature  PO4-P  NH3-N  mg/L  mg/L 0-100 mg/L 63°C  0-100 mg/L 63°C Ammonia Method Molybdate Phenate Reference 1 2 1: LaChat Instruments Methods Manual for the QuikChem Automated Ion Analyzer (1990). QuikChem method number 10-115-01-1Z 2: APHA, AWWA, WPCF (1995). Method 4500-NH3-F. Phenate Method  107  Appendix B: Mass balance data Table B. 1 2009 nitrogen balance 100°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  112 0.05 200 50000 1400.00 1.40  102 0.05 200 50040 1276.02 1.28  105 0.05 200 49990 1312.24 1.31  mg/L L mg g g  295 0.75 221.25 0.22125 1.62 0.1364688 0.8635312  300 0.75 225 0.225 1.50 0.149898069 0.850101931  321 0.75 241 0.24 1.55 0.155023785 0.844976215  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  89.4 0.05 200 73910 1651.89 1.65  72.3 0.05 200 76180 1376.95 1.38  87.8 0.05 200 72690 1595.55 1.60  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  211 0.05 200 2610 137.68 0.14  196 0.05 200 1490 73.01 0.07  216 0.05 200 1540 83.16 0.08  mg/L L mg g  67.6 0.05 3.38 0.00  39.1 0.05 1.96 0.00  94.3 0.05 4.72 0.00  mg/L L g  324.2 0.005 0.001621  219 0.005 0.001095  281 0.005 0.001405  mg/L  187  188  229  START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  15 mins  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper Feed Conc N as NH3 Vol. sample Ammount of N in feed Conc N as NH3  108  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of N in feed  L g  0.005 0.000935  0.005 0.00094  0.005 0.001145  30 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  133 0.005 0.000665  167 0.005 0.000835  218 0.005 0.00109  45 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  107 0.005 0.000535  158 0.005 0.00079  207 0.005 0.001035  60 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  84.5 0.005 0.0004225  162 0.005 0.00081  196 0.005 0.00098  75 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  63.8 0.005 0.000319  158 0.005 0.00079  206 0.005 0.00103  90 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  45.2 0.005 0.000226  155 0.005 0.000775  202 0.005 0.00101  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  36.6 0.005 0.000183  153 0.005 0.000765  213 0.005 0.001065  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  25.2 0.71 0.017892  156 0.71 0.11076  206 0.71 0.14626  g  1.82 0.02 0.14 1.65 0.00 -0.19  1.57 0.11 0.07 1.38 0.01 -0.07  1.84 0.15 0.09 1.60 0.01 -0.29  0.20 112  0.11 105  0.09 118  105 mins  120 mins  TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  109  Table B. 2 2009 nitrogen balance 120°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite  mg/L L mg mg mg g  105 0.05 200 50000 1312.50 1.31  90.1 0.05 200 50030 1126.93 1.13  105 0.05 200 49990 1312.24 1.31  Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed  mg/L L mg g  290 0.75 217.5 0.2175  314 0.75 235.5 0.2355  327 0.75 245 0.25  g  1.53 0.142156 9 0.857843 1  1.36 0.17285345 6 0.82714654 4  1.56 0.15746514 8 0.84253485 2  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  84.9 0.05 200 71070 1508.46 1.51  61.5 0.05 200 76670 1178.80 1.18  73.4 0.05 200 78760 1445.25 1.45  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  217 0.05 200 3670 199.10 0.20  201 0.05 200 2010 101.00 0.10  222 0.05 200 1850 102.68 0.10  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper  mg/L L mg g  77.8 0.05 3.89 0.00  50 0.05 2.50 0.00  139 0.05 6.95 0.01  Feed Conc N as NH3 Vol. sample  mg/L L  319 0.005  168 0.005  230 0.005  Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  110  Sample  Unit  pH 8  pH 9  pH 10  Ammount of N in feed  g  0.001595  0.00084  0.00115  15 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  170 0.005 0.00085  138 0.005 0.00069  185 0.005 0.000925  30 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  115 0.005 0.000575  133 0.005 0.000665  166 0.005 0.00083  45 mins  Conc N as NH3 Vol. sample  mg/L L  124 0.005  165 0.005  0.00062  0.000825  Ammount of N in feed  g  89.5 0.005 0.000447 5  60 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  71.8 0.005 0.000359  116 0.005 0.00058  161 0.005 0.000805  75 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  52.4 0.005 0.000262  117 0.005 0.000585  167 0.005 0.000835  90 mins  Conc N as NH3 Vol. sample  mg/L L  112 0.005  160 0.005  0.00056  0.0008  105 mins  120 mins  Ammount of N in feed  g  36.3 0.005 0.000181 5  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  25.4 0.005 0.000127  108 0.005 0.00054  159 0.005 0.000795  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  17.4 0.71 0.012354  102 0.71 0.07242  153 0.71 0.10863  g  1.73 0.01 0.20 1.51 0.00 -0.20  1.36 0.07 0.10 1.18 0.01 0.00  1.67 0.11 0.11 1.45 0.01 -0.11  0.20 113  0.16 100  0.13 107  TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  111  Table B. 3 2009 nitrogen balance 140°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite  mg/L L mg mg mg g  89.9 0.05 200 50000 1123.75 1.12  59.6 0.05 200 50000 745.00 0.75  86.1 0.05 200 50010 1076.47 1.08  Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed  mg/L L mg g  300 0.75 225 0.225  286 0.75 214.5 0.2145  316 0.75 237 0.24  g  1.35 0.166821 1 0.833178 9  0.96 0.22355393 4 0.77644606 6  1.31 0.18043872 9 0.81956127 1  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  74.3 0.05 200 66950 1243.60 1.24  67.3 0.05 200 71010 1194.74 1.19  51.3 0.05 200 78250 1003.56 1.00  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  208 0.05 200 6170 320.84 0.32  145 0.05 200 4140 150.08 0.15  248 0.05 200 4380 271.56 0.27  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper  mg/L L mg g  110 0.05 5.50 0.01  81.5 0.05 4.08 0.00  196 0.05 9.80 0.01  Feed Conc N as NH3 Vol. sample  mg/L L  329 0.005  193 0.005  218 0.005  Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  112  Sample 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Unit  pH 8  pH 9  pH 10  Ammount of N in feed  g  0.001645  0.000965  0.00109  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  164 0.005 0.00082  103 0.005 0.000515  130 0.005 0.00065  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  97.9 0.005 0.0004895  79.3 0.005 0.0003965  115 0.005 0.000575  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  54.8 0.005 0.000274  61.3 0.005 0.0003065  104 0.005 0.00052  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  35 0.005 0.000175  47.2 0.005 0.000236  100 0.005 0.0005  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  26 0.005 0.00013  28.9 0.005 0.0001445  98 0.005 0.00049  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  13.8 0.005 0.000069  15.6 0.005 0.000078  91 0.005 0.000455  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  10 0.005 0.00005  5.6 0.005 0.000028  90.4 0.005 0.000452  Conc N as NH3 Vol. sample Ammount of N in feed TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE  mg/L L g g  8.38 0.71 0.0059498 1.58 0.01 0.33 1.24 0.00 -0.23  2.37 0.71 0.0016827 1.35 0.00 0.15 1.19 0.00 -0.39  86.2 0.71 0.061202 1.35 0.06 0.28 1.00 0.00 -0.04  0.22 117  0.21 141  0.17 103  Reduction of mass in solution RECOVERY (%)  g  113  Table B. 4 2009 nitrogen balance 160°C  Sample START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  69.8 0.05 200 50000 872.50 0.87  58.4 0.05 200 50030 730.44 0.73  75.1 0.05 200 49990 938.56 0.94  mg/L L mg g  301 0.75 225.75 0.22575  298 0.75 223.5 0.2235  326 0.75 245 0.24  g  1.10 0.205554 3 0.794445 7  0.95 0.23429195 6 0.76570804 4  1.18 0.20666706 3 0.79333293 7  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  60.4 0.05 200 66280 1000.83 1.00  49.1 0.05 200 72370 888.34 0.89  51 0.05 200 73050 931.39 0.93  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  168 0.05 200 5830 244.86 0.24  207 0.05 200 3140 162.50 0.16  188 0.05 200 3250 152.75 0.15  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper  mg/L L mg g  187 0.05 9.35 0.01  63.5 0.05 3.18 0.00  249 0.05 12.45 0.01  Feed Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  325 0.005 0.001625  216 0.005 0.00108  261 0.005 0.001305  Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  114  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  137 0.005 0.000685  124 0.005 0.00062  130 0.005 0.00065  30 mins  Conc N as NH3 Vol. sample  mg/L L  94 0.005  115 0.005  0.00047  0.000575  Ammount of N in feed  g  47.5 0.005 0.000237 5  45 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  20.2 0.005 0.000101  67.6 0.005 0.000338  128 0.005 0.00064  60 mins  Conc N as NH3 Vol. sample  mg/L L  51.2 0.005  113 0.005  0.000256  0.000565  Ammount of N in feed  g  12.5 0.005 0.000062 5  75 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  8.93 0.005 4.465E-05  39.7 0.005 0.0001985  95.9 0.005 0.0004795  90 mins  Conc N as NH3 Vol. sample  mg/L L  32.2 0.005  99 0.005  0.000161  0.000495  Ammount of N in feed  g  6.22 0.005 0.000031 1  105 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  6.41 0.005 3.205E-05  23.3 0.005 0.0001165  94.2 0.005 0.000471  120 mins  Conc N as NH3 Vol. sample  mg/L L  6.24 0.71 0.004430 4  7.27 0.71  88.8 0.71  0.0051617  0.063048  1.26 0.00 0.25 1.00 0.00 -0.16  1.06 0.01 0.17 0.89 0.00 -0.11  1.16 0.06 0.17 0.93 0.01 0.02  0.22 115  0.22 111  0.18 98  Ammount of N in feed  g  TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE  g  Reduction of mass in solution RECOVERY (%)  g  115  Table B. 5 2009 nitrogen balance 180°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  56.2 0.05 200 50000 702.50 0.70  53.6 0.05 200 49990 669.87 0.67  83.7 0.05 200 50010 1046.46 1.05  mg/L L mg g  293 0.75 219.75 0.21975  290 0.75 217.5 0.2175  332 0.75 249 0.25  g  0.9223 0.238276 0.761724  0.8874 0.24510743 0.75489257  1.2955 0.192209828 0.807790172  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  45.2 0.05 200 56710 640.82 0.64  55.7 0.05 200 66720 929.08 0.93  51.3 0.05 200 63760 817.72 0.82  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  155 0.05 200 8740 338.68 0.34  224 0.05 200 4100 229.60 0.23  160 0.05 200 4930 197.20 0.20  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper  mg/L L mg g  130 0.05 6.50 0.01  81.5 0.05 4.08 0.00  169 0.05 8.45 0.01  Feed Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  323 0.005 0.001615  216 0.005 0.00108  294 0.005 0.00147  Conc N as NH3  mg/L  170  113  224  START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  15 mins  116  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of N in feed  L g  0.005 0.00085  0.005 0.000565  0.005 0.00112  30 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  56.2 0.005 0.000281  66.1 0.005 0.0003305  198 0.005 0.00099  45 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  15.9 0.005 0.0000795  50.7 0.005 0.0002535  182 0.005 0.00091  60 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  5.43 0.005 2.715E-05  32.4 0.005 0.000162  163 0.005 0.000815  75 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  5.36 0.005 0.0000268  16.9 0.005 0.0000845  174 0.005 0.00087  90 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  3.7 0.005 0.0000185  8.6 0.005 0.000043  164 0.005 0.00082  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  5.3 0.005 0.0000265  4.21 0.005 0.00002105  153 0.005 0.000765  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  6.48 0.71 0.0046008  4.54 0.71 0.0032234  159 0.71 0.11289  g  0.99 0.00 0.35 0.64 0.00 -0.07  1.17 0.00 0.23 0.93 0.00 -0.28  1.14 0.11 0.21 0.82 0.01 0.15  0.21 108  0.21 132  0.13 88  105 mins  120 mins  TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  117  Table B. 6 2009 nitrogen balance 200°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  45.4 0.05 200 50000 567.50 0.57  46.6 0.05 200 50010 582.62 0.58  49.9 0.05 200 50020 624.00 0.62  mg/L L mg g  298 0.75 223.5 0.2235  321 0.75 240.75 0.24075  317 0.75 238 0.24  g  0.79 0.2825537 0.7174463  0.82 0.292397128 0.707602872  0.86 0.27589224 0.72410776  Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of N in struvite after uptake Amount of N in struvite after uptake  mg/L L mg mg mg g  37.5 0.05 200 55400 519.38 0.52  34.7 0.05 200 68170 591.37 0.59  37.4 0.05 200 67560 631.69 0.63  Fines Conc N as NH3 Vol. sample Wt sample for digesting Wt fines Amount of N in fines Amount of N in fines  mg/L L mg mg mg g  172 0.05 200 7000 301.00 0.30  202 0.05 200 2640 133.32 0.13  193 0.05 200 2030 97.95 0.10  Filter Paper Conc N as NH3 Vol. sample Amount of N on filter paper Amount of N in filter paper  mg/L L mg g  167 0.05 8.35 0.01  54.7 0.05 2.74 0.00  61.1 0.05 3.06 0.00  Feed Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  325 0.005 0.001625  298 0.005 0.00149  259 0.005 0.001295  START Roasted struvite Conc N as NH3 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of N in roasted struvite Amount of N in roasted struvite Feed Conc N as NH3 Vol. sample Amount of N in feed Amount of N in feed Total N to start Proportion of Mass N in feed Proportion of N in calcinated pellets END  0 mins  118  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  226 0.005 0.00113  143 0.005 0.000715  231 0.005 0.001155  30 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  152 0.005 0.00076  111 0.005 0.000555  197 0.005 0.000985  45 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  58.5 0.005 0.0002925  103 0.005 0.000515  181 0.005 0.000905  60 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  40.3 0.005 0.0002015  81.4 0.005 0.000407  184 0.005 0.00092  75 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  14.4 0.005 0.000072  72.1 0.005 0.0003605  163 0.005 0.000815  90 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  6.81 0.005 3.405E-05  55.2 0.005 0.000276  166 0.005 0.00083  105 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  6.11 0.005 3.055E-05  56.8 0.005 0.000284  169 0.005 0.000845  120 mins  Conc N as NH3 Vol. sample Ammount of N in feed  mg/L L g  5.06 0.71 0.0035926  55.4 0.71 0.039334  164 0.71 0.11644  g  0.84 0.00 0.31 0.52 0.00 -0.05  0.77 0.04 0.14 0.59 0.00 0.05  0.86 0.12 0.10 0.63 0.01 0.00  0.22 106  0.20 94  0.11 99  TOTAL N AT END Mass N remain in soln (g) Mass in fines + filter (g) Mass N in uptake pellets (g) Mass N lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  119  Table B. 7 2009 phosphorus balance 100°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  846 0.05 200 50000 10575.00 10.58  930 0.05 200 50040 11634.30 11.63  839 0.05 200 49990 10485.40 10.49  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  21.5 0.75 16.125 0.016125  10.4 0.75 7.8 0.0078  36.3 0.75 27 0.03  g  10.59 0.001522 5 0.998477 5  11.64 0.00066998 2 0.99933001 8  10.51 0.00258974 3 0.99741025 7  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  586 0.05 200 73910 10827.82 10.83  527 0.05 200 76180 10036.72 10.04  607 0.05 200 72690 11030.71 11.03  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  561 0.05 200 2610 366.05 0.37  538 0.05 200 1490 200.41 0.20  570 0.05 200 1540 219.45 0.22  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  156 0.05 7.80 0.01  95.8 0.05 4.79 0.00  84.5 0.05 4.23 0.00  Feed Conc P as PO4 Vol. sample  mg/L L  80.7 0.005  69.9 0.005  96.4 0.005  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  120  Sample 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Unit  pH 8  pH 9  pH 10  Ammount of P in feed  g  0.0004035  0.0003495  0.000482  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  107 0.005 0.000535  81.3 0.005 0.0004065  107 0.005 0.000535  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  130 0.005 0.00065  83.7 0.005 0.0004185  108 0.005 0.00054  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  154 0.005 0.00077  84.3 0.005 0.0004215  114 0.005 0.00057  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  177 0.005 0.000885  89 0.005 0.000445  110 0.005 0.00055  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  203 0.005 0.001015  90.8 0.005 0.000454  100 0.005 0.0005  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  225 0.005 0.001125  93 0.005 0.000465  110 0.005 0.00055  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  260 0.005 0.0013  97.4 0.005 0.000487  111 0.005 0.000555  Conc P as PO4 Vol. sample Ammount of P in feed TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE  mg/L L g g  251 0.71 0.17821 11.39 0.18 0.37 10.83 0.01 -0.80  98.6 0.71 0.070006 10.32 0.07 0.21 10.04 0.00 1.33  105 0.71 0.07455 11.33 0.07 0.22 11.03 0.00 -0.82  -0.17 108  -0.07 89  -0.05 108  Reduction of mass in solution RECOVERY (%)  g  121  Table B. 8 2009 phosphorus balance 120°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  908 0.05 200 50000 11350.00 11.35  763 0.05 200 50030 9543.22 9.54  796 0.05 200 49990 9948.01 9.95  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  15.6 0.75 11.7 0.0117  9.09 0.75 6.8175 0.0068175  10.9 0.75 8 0.01  g  11.36 0.001029 8 0.998970 2  9.55 0.00071387 1 0.99928612 9  9.96 0.00082109 8 0.99917890 2  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  565 0.05 200 71070 10038.64 10.04  443 0.05 200 76670 8491.20 8.49  572 0.05 200 78760 11262.68 11.26  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  533 0.05 200 3670 489.03 0.49  506 0.05 200 2010 254.27 0.25  552 0.05 200 1850 255.30 0.26  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  169 0.05 8.45 0.01  123 0.05 6.15 0.01  136 0.05 6.80 0.01  Feed Conc P as PO4 Vol. sample  mg/L L  10.7 0.005  115 0.005  72.2 0.005  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  122  Sample 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Unit  pH 8  pH 9  pH 10  Ammount of P in feed  g  0.0000535  0.000575  0.000361  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  104 0.005 0.00052  132 0.005 0.00066  84 0.005 0.00042  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  132 0.005 0.00066  134 0.005 0.00067  87.1 0.005 0.0004355  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  151 0.005 0.000755  137 0.005 0.000685  83.8 0.005 0.000419  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  181 0.005 0.000905  138 0.005 0.00069  84.9 0.005 0.0004245  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  200 0.005 0.001  141 0.005 0.000705  91 0.005 0.000455  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  235 0.005 0.001175  143 0.005 0.000715  88.8 0.005 0.000444  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  264 0.005 0.00132  149 0.005 0.000745  94.8 0.005 0.000474  Conc P as PO4 Vol. sample Ammount of P in feed TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE  mg/L L g g  281 0.71 0.19951 10.74 0.20 0.50 10.04 0.01 0.62  151 0.71 0.10721 8.86 0.11 0.26 8.49 0.01 0.69  98 0.71 0.06958 11.60 0.07 0.26 11.26 0.00 -1.64  -0.19 95  -0.11 93  -0.06 116  Reduction of mass in solution RECOVERY (%)  g  123  Table B. 9 2009 phosphorus balance 140°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  739 0.05 200 50000 9237.50 9.24  608 0.05 200 50000 7600.00 7.60  834 0.05 200 50010 10427.09 10.43  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  20.1 0.75 15.075 0.015075  11.2 0.75 8.4 0.0084  13.9 0.75 10 0.01  g  9.25 0.001629 3 0.998370 7  7.61 0.00110404 3 0.99889595 7  10.44 0.00099880 1 0.99900119 9  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  590 0.05 200 66950 9875.13 9.88  526 0.05 200 71010 9337.82 9.34  517 0.05 200 78250 10113.81 10.11  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  533 0.05 200 6170 822.15 0.82  445 0.05 200 4140 460.58 0.46  531 0.05 200 4380 581.45 0.58  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  258 0.05 12.90 0.01  191 0.05 9.55 0.01  193 0.05 9.65 0.01  Feed Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  12.4 0.005 0.000062  101 0.005 0.000505  123 0.005 0.000615  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  124  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  157 0.005 0.000785  115 0.005 0.000575  132 0.005 0.00066  30 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  244 0.005 0.00122  113 0.005 0.000565  133 0.005 0.000665  45 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  238 0.005 0.00119  119 0.005 0.000595  137 0.005 0.000685  60 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  251 0.005 0.001255  128 0.005 0.00064  123 0.005 0.000615  75 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  279 0.005 0.001395  135 0.005 0.000675  125 0.005 0.000625  90 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  297 0.005 0.001485  150 0.005 0.00075  127 0.005 0.000635  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  377 0.005 0.001885  174 0.005 0.00087  144 0.005 0.00072  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  392 0.71 0.27832  229 0.71 0.16259  141 0.71 0.10011  g  11.00 0.28 0.84 9.88 0.01 -1.75  9.98 0.16 0.47 9.34 0.01 -2.37  10.81 0.10 0.59 10.11 0.01 -0.37  -0.27 119  -0.16 131  -0.09 104  105 mins  120 mins  TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  125  Table B. 10 2009 phosphorus balance 160°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  680 0.05 200 50000 8500.00 8.50  577 0.05 200 50030 7216.83 7.22  724 0.05 200 49990 9048.19 9.05  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  27.7 0.75 20.775 0.020775  11.8 0.75 8.85 0.00885  13.7 0.75 10 0.01  g  8.52 0.002438 2 0.997561 8  7.23 0.00122479 9 0.99877520 1  9.06 0.00113429 8 0.99886570 2  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  535 0.05 200 66280 8864.95 8.86  448 0.05 200 72370 8105.44 8.11  484 0.05 200 73050 8839.05 8.84  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  488 0.05 200 5830 711.26 0.71  508 0.05 200 3140 398.78 0.40  485 0.05 200 3250 394.06 0.39  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  485 0.05 24.25 0.02  170 0.05 8.50 0.01  556 0.05 27.80 0.03  Feed Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  19.8 0.005 0.000099  104 0.005 0.00052  100 0.005 0.0005  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  126  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  200 0.005 0.001  128 0.005 0.00064  128 0.005 0.00064  30 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  246 0.005 0.00123  128 0.005 0.00064  126 0.005 0.00063  45 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  282 0.005 0.00141  126 0.005 0.00063  120 0.005 0.0006  60 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  339 0.005 0.001695  136 0.005 0.00068  116 0.005 0.00058  75 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  371 0.005 0.001855  139 0.005 0.000695  112 0.005 0.00056  90 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  383 0.005 0.001915  145 0.005 0.000725  107 0.005 0.000535  105 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  410 0.005 0.00205  164 0.005 0.00082  109 0.005 0.000545  120 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  412 0.71 0.29252  197 0.71 0.13987  103 0.71 0.07313  g  9.90 0.29 0.74 8.86 0.01 -1.38  8.66 0.14 0.41 8.11 0.01 -1.43  9.34 0.07 0.42 8.84 0.00 -0.28  -0.28 116  -0.14 120  -0.07 103  TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  127  Table B. 11 2009 phosphorus balance 180°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  577 0.05 200 50000 7212.50 7.21  561 0.05 200 49990 7011.10 7.01  687 0.05 200 50010 8589.22 8.59  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  22.5 0.75 16.875 0.016875  14.4 0.75 10.8 0.0108  12 0.75 9 0.01  g  7.2294 0.002334 2 0.997665 8  7.0219 0.00153804 6 0.99846195 4  8.5982 0.00104672 9 0.99895327 1  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  435 0.05 200 56710 6167.21 6.17  466 0.05 200 66720 7772.88 7.77  462 0.05 200 63760 7364.28 7.36  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  462 0.05 200 8740 1009.47 1.01  558 0.05 200 4100 571.95 0.57  478 0.05 200 4930 589.14 0.59  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  325 0.05 16.25 0.02  167 0.05 8.35 0.01  172 0.05 8.60 0.01  Feed Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  13.2 0.005 0.000066  90.7 0.005 0.0004535  51 0.005 0.000255  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  128  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  208 0.005 0.00104  138 0.005 0.00069  43.2 0.005 0.000216  30 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  261 0.005 0.001305  151 0.005 0.000755  38.5 0.005 0.0001925  45 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  366 0.005 0.00183  155 0.005 0.000775  32.9 0.005 0.0001645  60 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  390 0.005 0.00195  164 0.005 0.00082  30.5 0.005 0.0001525  75 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  443 0.005 0.002215  169 0.005 0.000845  27.5 0.005 0.0001375  90 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  466 0.005 0.00233  207 0.005 0.001035  25.9 0.005 0.0001295  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  442 0.005 0.00221  219 0.005 0.001095  24.4 0.005 0.000122  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  432 0.71 0.30672  254 0.71 0.18034  21.1 0.71 0.014981  g  7.51 0.31 1.03 6.17 0.01 -0.28  8.54 0.18 0.58 7.77 0.01 -1.52  7.98 0.01 0.60 7.36 0.00 0.62  -0.30 104  -0.18 122  -0.01 93  105 mins  120 mins  TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  129  Table B. 12 2009 phosphorus balance 200°C  Sample  Unit  pH 8  pH 9  pH 10  START Roasted struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite for uptake Amount of P in roasted struvite Amount of P in roasted struvite  mg/L L mg mg mg g  511 0.05 200 50000 6387.50 6.39  559 0.05 200 50010 6988.90 6.99  564 0.05 200 50020 7052.82 7.05  Feed Conc P as PO4 Vol. sample Amount of P in feed Amount of P in feed  mg/L L mg g  24 0.75 18 0.018  12 0.75 9 0.009  11.6 0.75 9 0.01  g  6.41 0.002810 1 0.997189 9  7.00 0.00128610 1 0.99871389 9  7.06 0.00123202 9 0.99876797 1  Uptake: struvite Conc P as PO4 Vol. sample Wt sample for digesting Wt struvite after uptake Amount of P in struvite after uptake Amount of P in struvite after uptake  mg/L L mg mg mg g  366 0.05 200 55400 5069.10 5.07  391 0.05 200 68170 6663.62 6.66  373 0.05 200 67560 6299.97 6.30  Fines Conc P as PO4 Vol. sample Wt sample for digesting Wt fines Amount of P in fines Amount of P in fines  mg/L L mg mg mg g  460 0.05 200 7000 805.00 0.81  493 0.05 200 2640 325.38 0.33  469 0.05 200 2030 238.02 0.24  Filter Paper Conc P as PO4 Vol. sample Amount of P on filter paper Amount of P in filter paper  mg/L L mg g  390 0.05 19.50 0.02  118 0.05 5.90 0.01  130 0.05 6.50 0.01  Feed Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  14.3 0.005 0.000071  134 0.005 0.00067  39 0.005 0.000195  Total P to start Proportion of Mass P in feed Proportion of P in calcinated pellets END  0 mins  130  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  183 0.005 0.000915  82.5 0.005 0.0004125  51.3 0.005 0.0002565  30 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  193 0.005 0.000965  95.5 0.005 0.0004775  16.6 0.005 0.000083  45 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  227 0.005 0.001135  96.1 0.005 0.0004805  13 0.005 0.000065  60 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  268 0.005 0.00134  95.2 0.005 0.000476  10.9 0.005 0.0000545  75 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  288 0.005 0.00144  97.1 0.005 0.0004855  10.9 0.005 0.0000545  90 mins  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  354 0.005 0.00177  95.1 0.005 0.0004755  10.4 0.005 0.000052  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  374 0.005 0.00187  93.1 0.005 0.0004655  9.35 0.005 0.00004675  Conc P as PO4 Vol. sample Ammount of P in feed  mg/L L g  369 0.71 0.26199  93.6 0.71 0.066456  9.44 0.71 0.0067024  g  6.17 0.26 0.82 5.07 0.01 0.24  7.07 0.07 0.33 6.66 0.00 -0.07  6.55 0.01 0.24 6.30 0.00 0.51  -0.25 96  -0.06 101  0.00 93  105 mins  120 mins  TOTAL P AT END Mass P remain in soln (g) Mass in fines + filter (g) Mass P in uptake pellets (g) Mass P lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  131  Table B. 13 2009 magnesium balance 100°C  Sample START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  558.125 0.05 200 50000 6976.56 6.98  534.595 0.05 200 50040 6687.78 6.69  445.265 0.05 200 49990 5564.70 5.56  mg/L L mg  2.5635 0.75 1.922625 0.001922 6  28.323 0.75 21.24225  30.62 0.75 23  0.02124225  0.02  6.71  Amount of Mg in feed  g  Total Mg to start  g  Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets  6.98 0.000275 5 0.999724 5  0.00316622 0.99683378  5.59 0.00410994 6 0.99589005 4  END  0 mins  Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake  mg/L L mg mg mg g  377.82 0.05 200 73910 6981.17 6.98  338.585 0.05 200 76180 6448.35 6.45  336.215 0.05 200 72690 6109.87 6.11  Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  mg/L L mg mg mg g  355.68 0.05 200 2610 232.08 0.23  400.205 0.05 200 1490 149.08 0.15  409.135 0.05 200 1540 157.52 0.16  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  97.555 0.05 4.88 0.00  54.902 0.05 2.75 0.00  62.6125 0.05 3.13 0.00  Feed Conc Mg Vol. sample  mg/L L  10.334 0.005  2.3755 0.005  g  5.167E-05  5.369 0.005 0.00002684 5  Ammount of Mg in feed  1.18775E-05  132  Sample  Unit  pH 8  pH 9  pH 10  15 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  7.1505 0.005 3.575E-05  2.0095 0.005 1.00475E-05  2.13 0.005 0.00001065  30 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  4.4105 0.005 2.205E-05  2.1565 0.005 1.07825E-05  1.706 0.005 0.00000853  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  3.025 0.005 1.513E-05  1.8325 0.005 9.1625E-06  1.6275 0.005 8.1375E-06  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  5.5465 0.005 2.773E-05  2.59 0.005 0.00001295  1.7675 0.005 8.8375E-06  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  1.729 0.005 8.645E-06  2.4095 0.005 1.20475E-05  1.9055 0.005 9.5275E-06  90 mins  Conc Mg Vol. sample  mg/L L  1.928 0.005 0.00000964  2.031 0.005 0.00001015 5  105 mins  120 mins  Ammount of Mg in feed  g  26.411 0.005 0.000132 1  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  14.8145 0.005 7.407E-05  1.8995 0.005 9.4975E-06  1.3155 0.005 6.5775E-06  Conc Mg Vol. sample  mg/L L  6.116 0.71 0.004342 4  1.9635 0.71 0.00139408 5  1.883 0.71 0.00133693  7.22 0.00 0.24 6.98 0.00 -0.24  6.60 0.00 0.15 6.45 0.00 0.11  6.27 0.00 0.16 6.11 0.00 -0.68  0.00 104  0.02 98  0.02 112  Ammount of Mg in feed  g  TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE  g  Reduction of mass in solution RECOVERY (%)  g  133  Table B. 14 2009 magnesium balance 120°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  528.945 0.05 200 50000 6611.81 6.61  550.155 0.05 200 50030 6881.06 6.88  600.42 0.05 200 49990 7503.75 7.50  mg/L L mg g g  3.4015 0.75 2.551125 0.0025511 6.61 0.0003857 0.9996143  26.1955 0.75 19.646625 0.019646625 6.90 0.002847044 0.997152956  35.143 0.75 26 0.03 7.53 0.003500249 0.996499751  Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake  mg/L L mg mg mg g  426.26 0.05 200 71070 7573.57 7.57  356.305 0.05 200 76670 6829.48 6.83  330.615 0.05 200 78760 6509.81 6.51  Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  mg/L L mg mg mg g  331.725 0.05 200 3670 304.36 0.30  392.72 0.05 200 2010 197.34 0.20  387.22 0.05 200 1850 179.09 0.18  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  35.575 0.05 1.78 0.00  79.6695 0.05 3.98 0.00  227.495 0.05 11.37 0.01  Feed Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  3.6065 0.005 1.803E-05  5.661 0.005 0.000028305  3.9515 0.005 1.97575E-05  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  3.224 0.005 1.612E-05  7.218 0.005 0.00003609  2.346 0.005 0.00001173  START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed Amount of Mg in feed Total Mg to start Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets END  0 mins  15 mins  134  Sample  Unit  pH 8  pH 9  pH 10  30 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  1.2475 0.005 6.238E-06  5.146 0.005 0.00002573  2.793 0.005 0.000013965  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  2.173 0.005 1.087E-05  3.831 0.005 0.000019155  3.2175 0.005 1.60875E-05  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  2.173 0.005 1.087E-05  4.188 0.005 0.00002094  3.226 0.005 0.00001613  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  7.9105 0.005 3.955E-05  4.175 0.005 0.000020875  3.2005 0.005 1.60025E-05  90 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  14.056 0.005 7.028E-05  4.0325 0.005 2.01625E-05  3.1655 0.005 1.58275E-05  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  25.746 0.005 0.0001287  4.9435 0.005 2.47175E-05  1.8175 0.005 9.0875E-06  Conc Mg Vol. sample Ammount of Mg in feed TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE  mg/L L g g  5.7625 0.71 0.0040914 7.88 0.00 0.31 7.57 0.00 -1.27  4.432 0.71 0.00314672 7.03 0.00 0.20 6.83 0.00 -0.13  4.0565 0.71 0.002880115 6.70 0.00 0.19 6.51 0.00 0.83  0.00 119  0.02 102  0.02 89  105 mins  120 mins  Reduction of mass in solution RECOVERY (%)  g  135  Table B. 15 2009 magnesium balance 140°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  507.745 0.05 200 50000 6346.81 6.35  460.25 0.05 200 50000 5753.13 5.75  526.545 0.05 200 50010 6583.13 6.58  mg/L L mg g g  6.7985 0.75 5.098875 0.0050989 6.35 0.0008027 0.9991973  28.5885 0.75 21.441375 0.021441375 5.77 0.003713071 0.996286929  27.5075 0.75 21 0.02 6.60 0.003124073 0.996875927  mg/L L mg mg mg g  414.535 0.05 200 66950 6938.28 6.94  403.015 0.05 200 71010 7154.52 7.15  287.29 0.05 200 78250 5620.11 5.62  mg/L L mg mg mg g  330.7 0.05 200 6170 510.10 0.51  344.835 0.05 200 4140 356.90 0.36  429.195 0.05 200 4380 469.97 0.47  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  206.065 0.05 10.30 0.01  134.86 0.05 6.74 0.01  327.19 0.05 16.36 0.02  Feed Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  38.706 0.005 0.0001935  11.859 0.005 0.000059295  4.6275 0.005 2.31375E-05  15 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  66.6185 0.005 0.0003331  13.1475 0.005 6.57375E-05  8.257 0.005 0.000041285  30 mins  Conc Mg  mg/L  51.0805  13.3695  10.588  START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed Amount of Mg in feed Total Mg to start Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets END Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  0 mins  136  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of Mg in feed  L g  0.005 0.0002554  0.005 6.68475E-05  0.005 0.00005294  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  55.735 0.005 0.0002787  15.3885 0.005 7.69425E-05  11.463 0.005 0.000057315  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  68.7255 0.005 0.0003436  16.968 0.005 0.00008484  12.4735 0.005 6.23675E-05  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  82.277 0.005 0.0004114  19.1225 0.005 9.56125E-05  12.971 0.005 0.000064855  90 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  74.7505 0.005 0.0003738  24.509 0.005 0.000122545  13.2465 0.005 6.62325E-05  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  150.435 0.005 0.0007522  40.1565 0.005 0.000200783  12.5235 0.005 6.26175E-05  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  166.485 0.71 0.1182044  51.987 0.71 0.03691077  13.664 0.71 0.00970144  g  7.58 0.12 0.52 6.94 0.00 -1.23  7.56 0.04 0.36 7.15 0.00 -1.78  6.12 0.01 0.49 5.62 0.00 0.49  -0.12 119  -0.02 131  0.01 93  105 mins  120 mins  TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  137  Table B. 16 2009 magnesium balance 160°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  590.755 0.05 200 50000 7384.44 7.38  461.765 0.05 200 50030 5775.53 5.78  971.415 0.05 200 49990 12140.26 12.14  mg/L L mg g g  35.0835 0.75 26.312625 0.0263126 7.41 0.0035506 0.9964494  32.135 0.75 24.10125 0.02410125 5.80 0.004155655 0.995844345  32.4115 0.75 24 0.02 12.16 0.001998314 0.998001686  mg/L L mg mg mg g  436.385 0.05 200 66280 7230.90 7.23  377.77 0.05 200 72370 6834.80 6.83  389.55 0.05 200 73050 7114.16 7.11  mg/L L mg mg mg g  348.38 0.05 200 5830 507.76 0.51  369.735 0.05 200 3140 290.24 0.29  313.235 0.05 200 3250 254.50 0.25  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  348.28 0.05 17.41 0.02  115.81 0.05 5.79 0.01  357.06 0.05 17.85 0.02  Feed Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  34.1185 0.005 0.0001706  13.064 0.005 0.00006532  6.4235 0.005 3.21175E-05  15 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  55.4185 0.005 0.0002771  14.612 0.005 0.00007306  11.5665 0.005 5.78325E-05  30 mins  Conc Mg  mg/L  73.5385  15.296  20.2225  START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed Amount of Mg in feed Total Mg to start Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets END Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  0 mins  138  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of Mg in feed  L g  0.005 0.0003677  0.005 0.00007648  0.005 0.000101113  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  73.3185 0.005 0.0003666  16.84 0.005 0.0000842  24.2205 0.005 0.000121103  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  78.32 0.005 0.0003916  20.5585 0.005 0.000102793  24.8635 0.005 0.000124318  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  83.1175 0.005 0.0004156  19.958 0.005 0.00009979  24.075 0.005 0.000120375  90 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  90.683 0.005 0.0004534  21.6575 0.005 0.000108288  26.605 0.005 0.000133025  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  170.595 0.005 0.000853  27.622 0.005 0.00013811  30.0545 0.005 0.000150273  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  162.905 0.71 0.1156626  25.5055 0.71 0.018108905  33.3745 0.71 0.023695895  g  7.88 0.12 0.53 7.23 0.00 -0.46  7.15 0.02 0.30 6.83 0.00 -1.35  7.41 0.02 0.27 7.11 0.00 4.75  -0.09 106  0.01 123  0.00 61  105 mins  120 mins  TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  139  Table B. 17 2009 magnesium balance 180°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  520.095 0.05 200 50000 6501.19 6.50  546.14 0.05 200 49990 6825.38 6.83  607.225 0.05 200 50010 7591.83 7.59  mg/L L mg g g  35.81 0.75 26.8575 0.0268575 6.5280 0.0041142 0.9958858  30.6935 0.75 23.020125 0.023020125 6.8484 0.003361385 0.996638615  33.017 0.75 25 0.02 7.6166 0.003251158 0.996748842  mg/L L mg mg mg g  415.79 0.05 200 56710 5894.86 5.89  485.765 0.05 200 66720 8102.56 8.10  444.44 0.05 200 63760 7084.37 7.08  mg/L L mg mg mg g  350.895 0.05 200 8740 766.71 0.77  423.33 0.05 200 4100 433.91 0.43  358.37 0.05 200 4930 441.69 0.44  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  232.02 0.05 11.60 0.01  111.3 0.05 5.57 0.01  283.325 0.05 14.17 0.01  Feed Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  38.11 0.005 0.0001906  18.5435 0.005 9.27175E-05  20.235 0.005 0.000101175  15 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  108.915 0.005 0.0005446  23.032 0.005 0.00011516  14.401 0.005 0.000072005  30 mins  Conc Mg  mg/L  131.525  28.1515  20.5035  START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed Amount of Mg in feed Total Mg to start Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets END Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  0 mins  140  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of Mg in feed  L g  0.005 0.0006576  0.005 0.000140758  0.005 0.000102518  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  176.04 0.005 0.0008802  29.908 0.005 0.00014954  23.989 0.005 0.000119945  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  209.145 0.005 0.0010457  32.0055 0.005 0.000160028  27.116 0.005 0.00013558  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  242.6 0.005 0.001213  34.4925 0.005 0.000172463  28.337 0.005 0.000141685  90 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  255.6 0.005 0.001278  51.5035 0.005 0.000257518  31.715 0.005 0.000158575  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  194.6 0.005 0.000973  53.9835 0.005 0.000269918  34.0485 0.005 0.000170243  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  168.02 0.71 0.1192942  64.385 0.71 0.04571335  36.3155 0.71 0.025784005  g  6.80 0.12 0.78 5.89 0.01 -0.27  8.59 0.05 0.44 8.10 0.00 -1.74  7.57 0.03 0.46 7.08 0.00 0.05  -0.10 104  -0.02 125  0.00 99  105 mins  120 mins  TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  141  Table B. 18 2009 magnesium balance 200°C  Sample  Unit  pH 8  pH 9  pH 10  mg/L L mg mg mg g  524.615 0.05 200 50000 6557.69 6.56  491.235 0.05 200 50010 6141.67 6.14  52.64 0.05 200 50020 658.26 0.66  mg/L L mg g g  40.475 0.75 30.35625 0.0303563 6.59 0.0046078 0.9953922  29.9265 0.75 22.444875 0.022444875 6.16 0.003641219 0.996358781  28.855 0.75 22 0.02 0.68 0.03182984 0.96817016  mg/L L mg mg mg g  418.05 0.05 200 55400 5789.99 5.79  327.145 0.05 200 68170 5575.37 5.58  57.225 0.05 200 67560 966.53 0.97  mg/L L mg mg mg g  332.725 0.05 200 7000 582.27 0.58  360.505 0.05 200 2640 237.93 0.24  145.39 0.05 200 2030 73.79 0.07  Filter Paper Conc Mg Vol. sample Amount of Mg on filter paper Amount of Mg in filter paper  mg/L L mg g  294.7 0.05 14.74 0.01  76.631 0.05 3.83 0.00  11.75 0.05 0.59 0.00  Feed Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  37.91 0.005 0.0001896  75.7965 0.005 0.000378983  29.112 0.005 0.00014556  15 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  156.54 0.005 0.0007827  27.3775 0.005 0.000136888  38.8465 0.005 0.000194233  30 mins  Conc Mg  mg/L  160.205  34.8695  22.452  START Roasted struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite for uptake Amount of Mg in roasted struvite Amount of Mg in roasted struvite Feed Conc Mg Vol. sample Amount of Mg in feed Amount of Mg in feed Total Mg to start Proportion of Mass Mg in feed Proportion of Mg in calcinated pellets END Uptake: struvite Conc Mg Vol. sample Wt sample for digesting Wt struvite after uptake Amount of Mg in struvite after uptake Amount of Mg in struvite after uptake Fines Conc Mg Vol. sample Wt sample for digesting Wt fines Amount of Mg in fines Amount of Mg in fines  0 mins  142  Sample  Unit  pH 8  pH 9  pH 10  Vol. sample Ammount of Mg in feed  L g  0.005 0.000801  0.005 0.000174348  0.005 0.00011226  45 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  159.65 0.005 0.0007983  35.626 0.005 0.00017813  28.0095 0.005 0.000140048  60 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  183.615 0.005 0.0009181  36.01 0.005 0.00018005  32.0795 0.005 0.000160398  75 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  187.415 0.005 0.0009371  34.855 0.005 0.000174275  34.6805 0.005 0.000173403  90 mins  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  227.17 0.005 0.0011359  30.58 0.005 0.0001529  35.553 0.005 0.000177765  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  226.965 0.005 0.0011348  30.481 0.005 0.000152405  39.0735 0.005 0.000195368  Conc Mg Vol. sample Ammount of Mg in feed  mg/L L g  208.285 0.71 0.1478824  27.4405 0.71 0.019482755  39.129 0.71 0.02778159  g  6.54 0.15 0.60 5.79 0.01 0.05  5.84 0.02 0.24 5.58 0.00 0.33  1.07 0.03 0.07 0.97 0.00 -0.39  -0.12 99  0.00 95  -0.01 157  105 mins  120 mins  TOTAL Mg AT END Mass Mg remain in soln (g) Mass in fines + filter (g) Mass Mg in uptake pellets (g) Mass Mg lost during sampling (g) DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  143  Table B. 19 2010 mass balance summary for N, P, and Mg  ID 9a 9b 9c 10a 10b 10c 11a 11b 11c 11d 12a 12b 12c 12d 15a 15b 15c 16a 16b 16c 17a 17b 17c  Conditions Constant pH 8, 2hour, T=105, Mass=20g Constant pH 8, 2hour, T=105, Mass=20g Initial pH 8, 2hour, T=105, Mass=20g Constant pH 8, 2hour, T=105, Mass=20g Rehydration pH 8, 15min, T=105, Mass=20g Constant pH 8, 2hour, T=105, Mass=40g Constant pH 8, 2hour, T=160, Mass=20g Constant pH 8, 2hour, T=160, Mass=40g Initial pH 8, 2hour, T=160, Mass=20g Initial pH 8 filtrate, 30min, T=160, Mass=20g Constant pH 8, 2hour, T=80, Mass=20g Rehydration, 15min, T=80, Mass=5.5g Constant pH 8, 2hour, T=80, Mass=20g Constant pH 8, 2hour, T=80, Mass=40g Constant pH 9, 2hour, T=80, Mass=20g Constant pH 9, 2hour, T=80, Mass=40g Diss-ref pH 9, 2hour, T=80, Mass=20g Diss-ref pH 9, 2hour, T=160, Mass=20g Constant pH 9, 2hour, T=160, Mass=20g Constant pH 9, 2hour, T=160, Mass=40g Diss-ref pH 9, 2hour, T=105, Mass=20g Constant pH 9, 2hour, T=105, Mass=20g Constant pH 9, 2hour, T=105, Mass=40g  N 94.5 92.6 85.7 110.2 110.4 102.6 98.9 97.8 100.9 95.3 105.7 107.9 103.8 104.3 101.1 94.9 99.5 74.5 102.2 81.6 96.3 112.8 122.1  P 107.5 107.6 105.4 103.0 95.0 102.6 101.9 103.7 72.9 91.4 119.4 202.1 114.9 135.5 104.2 99.7 100.9 84.4 98.2 62.9 98.6 100.9 91.4  Mg 96.5 97.6 97.2 103.9 102.7 101.7 99.8 101.0 85.9 110.7 120.4 190.7 119.3 119.3 100.9 101.1 99.3 87.8 100.1 67.4 91.4 165.7 93.2  144  Table B. 20 2010 nitrogen balance 80°C Temperature: 80°C Sample  12a  12b  12c  12d  15a  15b  15c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  5.41  5.41  5.41  5.41  4.92  4.92  4.92  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  40.7  40.7  40.7  40.7  47.3  47.3  47.3  Wt struvite for uptake  mg  20159.5  5489  19802.2  40048.3  20068.5  39729.1  19590  Amount of N in roasted struvite  mg  669.92  182.40  658.05  1330.84  521.87  1033.12  509.42  Amount of N in roasted struvite  g  0.67  0.18  0.66  1.33  0.52  1.03  0.51  mg/L  703  0.148  661  681  616  636  650  L  0.5  0.5  0.5  0.5  0.5  0.5  0.577  START Roasted struvite Conc N as NH3 Vol. sample  Feed Conc N as NH3 Vol. sample Amount of N in feed  mg  351.5  0.074  331  341  308  318  375  Amount of N in feed  g  0.3515  0.000074  0.33  0.34  0.31  0.32  0.38  Total N to start  g  1.02  0.18  0.99  1.67  0.83  1.35  0.88  Proportion of Mass N in feed  0.34  0.00  0.33  0.20  0.37  0.24  0.42  Proportion of N in calcinated pellets  0.66  1.00  0.67  0.80  0.63  0.76  0.58  mg/L  4.47  4.15  4.43  4.33  3.35  3.21  0  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  END Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting  mg  43.9  40.2  42.8  41.8  37.4  38.8  0  Wt struvite after uptake  mg  30659.5  7361.8  27926.5  56265.5  24887  49176  0  Amount of N in struvite after uptake  mg  780.46  190.00  722.63  1457.11  557.30  1017.11  0.00  Amount of N in struvite after uptake  g  0.78  0.19  0.72  1.46  0.56  1.02  0.00  mg/L  8.95  0  9.36  9.49  7.58  7.41  4.65 0.25  Fines Conc N as NH3  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.8  0  41.6  41.9  36.3  37.4  40.3  Wt fines  mg  427.7  23.8  417  918.7  135.2  393.3  30001.5  Amount of N in fines  mg  24.04  0.00  23.46  52.02  7.06  19.48  865.43  Amount of N in fines  g  0.02  0.00  0.02  0.05  0.01  0.02  0.87  Vol. sample  Filter Paper mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Conc N as NH3 Vol. sample  Feed 0 mins  mg/L  667  0  658  663  617  639  1700  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.003335  0  0.00329  0.003315  0.003085  0.003195  0.0085  Conc N as NH3  145  Temperature: 80°C 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  12a  Sample  Unit  Conc N as NH3  pH 8  12b  12c pH 8  12d pH 8  15a pH 8  15b pH 9  15c pH 9  pH 9  mg/L  599  0  599  545  563  523  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.002995  0  0.002995  0.002725  0.002815  0.002615  0  mg/L  588  0  587  522  563  515  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00294  0  0.002935  0.00261  0.002815  0.002575  0  Conc N as NH3  mg/L  554  0  573  495  551  512  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00277  0  0.002865  0.002475  0.002755  0.00256  0  Conc N as NH3  mg/L  561  0  573  483  565  502  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.002805  0  0.002865  0.002415  0.002825  0.00251  0  Conc N as NH3  mg/L  558  0  559  468  553  500  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00279  0  0.002795  0.00234  0.002765  0.0025  0  mg/L  572  0  583  476  560  500  0  Conc N as NH3  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00286  0  0.002915  0.00238  0.0028  0.0025  0  mg/L  559  0  549  474  506  486  0  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.002795  0  0.002745  0.00237  0.00253  0.00243  0  mg/L  548  13.9  557  464  548  488  10.5  Vol. sample  L  0.46  0.49  0.46  0.46  0.46  0.46  0.567  Ammount of N in feed  g  0.25208  0.006811  0.25622  0.21344  0.25208  0.22448  0.0059535  TOTAL N AT END  g  Conc N as NH3  1.08  0.20  1.03  1.74  0.84  1.28  0.88  Mass N remain in soln (g)  0.25  0.01  0.26  0.21  0.25  0.22  0.01  Mass in fines + filter (g)  0.02  0.00  0.02  0.05  0.01  0.02  0.87  Mass N in uptake pellets (g)  0.78  0.19  0.72  1.46  0.56  1.02  0.00  Mass N lost during sampling (g)  0.02  0.00  0.02  0.02  0.02  0.02  0.01  -0.06  -0.01  -0.04  -0.07  -0.01  0.07  0.00  Reduction of mass in solution  0.08  -0.01  0.05  0.11  0.03  0.07  0.36  RECOVERY (%)  106  108  104  104  101  95  99  DIFFERENCE  g  146  Table B. 21 2010 nitrogen balance 105°C 9a  Temperature: 105°C Sample  9b  9c  10a  10b  10c  17a  17b  17c  Unit  pH 8  pH 8  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  6.91  6.91  6.91  5.04  5.04  5.04  3.03  3.03  3.03 0.25  START Roasted struvite Conc N as NH3 Vol. sample  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41.2  41.2  41.2  38.4  38.4  38.4  35.4  35.4  35.4  Wt struvite for uptake  mg  20053.8  20026.6  20026  19950  19958  40551  19871  19911.7  39942.4  Amount of N in roasted struvite  mg  840.85  839.71  839.68  654.61  654.87  1330.58  425.21  426.08  854.70  Amount of N in roasted struvite  g  0.84  0.84  0.84  0.65  0.65  1.33  0.43  0.43  0.85  mg/L  578  677  680  661  3.27  663  767.5  871  939  L  0.5  0.5  0.5  0.5  0.5  0.5  0.6  0.5  0.5  Amount of N in feed  mg  289  338.5  340  331  2  332  461  436  470  Amount of N in feed  g  0.289  0.3385  0.34  0.33  0.00  0.33  0.46  0.44  0.47  Total N to start  g  Feed Conc N as NH3 Vol. sample  1.13  1.18  1.18  0.99  0.66  1.66  0.89  0.86  1.32  Proportion of Mass N in feed  0.26  0.29  0.29  0.34  0.00  0.20  0.52  0.51  0.35  Proportion of N in calcinated pellets  0.74  0.71  0.71  0.66  1.00  0.80  0.48  0.49  0.65  mg/L  4.59  4.15  4.87  4.15  3.65  3.66  0  3.97  4.04  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41  39.2  41.2  38.3  39.2  38.2  0  43.6  40.7  Wt struvite after uptake  mg  29071.2  30211.9  26399.5  30497.1  30427.8  61526.8  0  24837.8  51166.7  Amount of N in struvite after uptake  mg  813.64  799.61  780.13  826.13  708.30  1473.74  0.00  565.40  1269.74  Amount of N in struvite after uptake  g  0.81  0.80  0.78  0.83  0.71  1.47  0.00  0.57  1.27  mg/L  7.85  7.5  6.21  8.59  1.18  8.94  5.41  4.81  8.15 0.25  END Uptake: struvite Conc N as NH3 Vol. sample  Fines Conc N as NH3 Vol. sample  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  38.6  39  37.3  38  11.6  39.1  50.9  23  38.2  Wt fines  mg  391.2  516.7  45.8  507  34.5  1525  31605.3  120.4  234.8  Amount of N in fines  mg  19.89  24.84  1.91  28.65  0.88  87.17  839.81  6.29  12.52  Amount of N in fines  g  0.02  0.02  0.00  0.03  0.00  0.09  0.84  0.01  0.01  0  0  0  0  0  0  Filter Paper Conc N as NH3  mg/L  0  0  0  L  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  mg/L  712  679  676  679  0  671  1820  868  867  Vol. sample  Feed 0 mins  Conc N as NH3  147  9a  Temperature: 105°C Sample  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Unit  pH 8  9b  9c pH 8  10a pH 8  10b  10c  pH 8  pH 8  pH 8  17a  17b  pH 9  pH 9  17c pH 9  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00356  0.003395  0.00338  0.003395  0  0.003355  0.0091  0.00434  0.00434  Conc N as NH3  mg/L  610  597  0  604  0  476  0  765  792  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00305  0.002985  0  0.00302  0  0.00238  0  0.00383  0.00396  Conc N as NH3  mg/L  613  595  0  540  0  410  0  734  733  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.003065  0.002975  0  0.0027  0  0.00205  0  0.00367  0.00367  Conc N as NH3  mg/L  570  569  0  530  0  368  0  738  655  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00285  0.002845  0  0.00265  0  0.00184  0  0.00369  0.00328  mg/L  542  537  0  521  0  342  0  814  733  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00271  0.002685  0  0.002605  0  0.00171  0  0.00407  0.00367  Conc N as NH3  mg/L  519  559  0  501  0  321  0  763  693  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.002595  0.002795  0  0.002505  0  0.001605  0  0.00382  0.00347  Conc N as NH3  mg/L  515  569  0  494  0  300  0  758  732  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.002575  0.002845  0  0.00247  0  0.0015  0  0.00379  0.00366  Conc N as NH3  mg/L  496  561  0  466  0  286  0  772  703  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00248  0.002805  0  0.00233  0  0.00143  0  0.00386  0.00352  Conc N as NH3  mg/L  460  530  490  455  32.2  279  7.43  803  662  Vol. sample  L  0.46  0.46  0.46  0.46  0.49  0.46  0.56  0.46  0.46  Ammount of N in feed  g  0.2116  0.2438  0.2254  0.2093  0.01578  0.12834  0.0041608  0.36938  0.30452  TOTAL N AT END  g  1.07  1.09  1.01  1.09  0.72  1.71  0.85  0.97  1.62  Mass N remain in soln  g  0.21  0.24  0.23  0.21  0.02  0.13  0.00  0.37  0.30  Mass in fines + filter  g  0.02  0.02  0.00  0.03  0.00  0.09  0.84  0.01  0.01  Mass N in uptake pellets  g  0.81  0.80  0.78  0.83  0.71  1.47  0.00  0.57  1.27  Mass N lost during sampling  g  0.02  0.02  0.00  0.02  0.00  0.02  0.01  0.03  0.03  Reduction of mass in solution  g  0.05  0.07  0.11  0.10  -0.01  0.19  0.45  0.04  0.14  MASS BALANCE  g  0.06  0.09  0.17  -0.10  -0.07  -0.04  0.03  -0.11  -0.29  95  93  86  110  110  103  96  113  122  RECOVERY (%)  148  Table B. 22 2010 nitrogen balance 160°C 11a  Temperature: 160°C Sample  11b  11c  11d  16a  16b  16c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  3.57  3.57  3.57  0  2.32  2.32  2.32 0.25  START Roasted struvite Conc N as NH3 Vol. sample  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  39.6  39.6  0  40.5  40.5  40.5  Wt struvite for uptake  mg  19910.7  40334.9  20472.3  0  19990.3  19962.3  39673.8  Amount of N in roasted struvite  mg  448.74  909.06  461.40  0.00  286.28  285.88  568.17  Amount of N in roasted struvite  g  0.45  0.91  0.46  0.00  0.29  0.29  0.57  mg/L  691  698  673  520  875  699  727  L  0.5  0.5  0.5  0.46  0.564  0.5  0.5  Amount of N in feed  mg  345.5  349  337  239  494  350  364  Amount of N in feed  g  0.3455  0.349  0.34  0.24  0.49  0.35  0.36  Total N to start  g  0.79  1.26  0.80  0.24  0.78  0.64  0.93  Proportion of Mass N in feed  0.435004  0.277411  0.421731  1  0.63287  0.55006  0.39016  Proportion of N in calcinated pellets  0.564996  0.722589  0.578269  0  0.36713  0.44994  0.60984  mg/L  3.11  2.97  3.27  0  0  2.31  2.06  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  40  39.6  0  0  42.3  51.5  Wt struvite after uptake  mg  24809.6  50027.4  25818.7  0  0  24197.8  48258.1  Amount of N in struvite after uptake  mg  487.11  928.63  533.00  0.00  0.00  330.36  482.58  g  0.49  0.93  0.53  0.00  0.00  0.33  0.48  mg/L  8.72  12.5  4.77  8.8  3.92  4.97  5.88  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Feed Conc N as NH3 Vol. sample  END Uptake: struvite Conc N as NH3 Vol. sample  Amount of N in struvite after uptake Fines Conc N as NH3 Vol. sample Wt sample for digesting  mg  40.3  58.5  38.3  40.6  51.2  29.4  32  Wt fines  mg  2315  5275.9  406.5  2206.6  29792.9  88.5  182.3  Amount of N in fines  mg  125.23  281.83  12.66  119.57  570.25  3.74  8.37  Amount of N in fines  g  0.13  0.28  0.01  0.12  0.57  0.00  0.01  Filter Paper Conc N as NH3  mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Vol. sample  Feed 0 mins  Conc N as NH3  mg/L  675  687  673  0  1270  690  703  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.003375  0.003435  0.003365  0  0.00635  0.00345  0.00352  149  11a  Temperature: 160°C  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Sample  Unit  Conc N as NH3  pH 8  11b pH 8  11c pH 8  11d  16a  pH 8  pH 9  16b pH 9  16c pH 9  mg/L  594  308  627  255  0  630  571  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00297  0.00154  0.003135  0.00128  0  0.00315  0.00286  mg/L  462  197  600  215  0  613  558  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00231  0.000985  0.003  0.00108  0  0.00307  0.00279  Conc N as NH3  mg/L  430  154  586  0  0  631  550  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00215  0.00077  0.00293  0  0  0.00316  0.00275  Conc N as NH3  mg/L  402  122  557  0  0  660  544  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.00201  0.00061  0.002785  0  0  0.0033  0.00272  Conc N as NH3  mg/L  387  88.5  566  0  0  606  512  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.001935  0.000443  0.00283  0  0  0.00303  0.00256  Conc N as NH3  mg/L  369  68.9  568  0  0  717  543  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.001845  0.000345  0.00284  0  0  0.00359  0.00272  Conc N as NH3  mg/L  349  44.1  538  0  0  672  537  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.001745  0.000221  0.00269  0  0  0.00336  0.00269  Conc N as NH3  mg/L  337  26.2  512  241  8.29  629  537  Vol. sample  L  0.46  0.46  0.46  0.44  0.554  0.46  0.46  Ammount of N in feed  g  0.15502  0.012052  0.23552  0.10604  0.00459  0.28934  0.24702  TOTAL N AT END  g  0.79  1.23  0.80  0.23  0.58  0.65  0.76  Mass N remain in soln (g)  0.16  0.01  0.24  0.11  0.00  0.29  0.25  Mass in fines + filter (g)  0.13  0.28  0.01  0.12  0.57  0.00  0.01  Mass N in uptake pellets (g)  0.49  0.93  0.53  0.00  0.00  0.33  0.48  Mass N lost during sampling (g)  0.02  0.01  0.02  0.00  0.01  0.03  0.02  0.01  0.03  -0.01  0.01  0.20  -0.01  0.17  0.17  0.33  0.08  0.13  0.48  0.03  0.09  99  98  101  95  75  102  82  DIFFERENCE Reduction of mass in solution RECOVERY (%)  g  150  Table B. 23 2010 phosphorus balance 80°C Temperature: 80°C Sample  12a  12b  12c  12d  15a  15b  15c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  24.3  24.3  24.3  24.3  35.5  35.5  35.5  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  40.7  40.7  40.7  40.7  47.3  47.3  47.3  Wt struvite for uptake  mg  20159.5  5489  19802.2  40048.3  20068.5  39729.1  19590  Amount of P in roasted struvite  mg  3009.07  819.30  2955.73  5977.73  3765.50  7454.46  3675.71  Amount of P in roasted struvite  g  3.01  0.82  2.96  5.98  3.77  7.45  3.68  mg/L  11  0.382  9.43  35.9  9.2  9.38  9.26  L  0.5  0.5  0.5  0.5  0.5  0.5  0.577  START Roasted struvite Conc P as PO4 Vol. sample  Feed Conc P as PO4 Vol. sample Amount of P in feed  mg  5.5  0.191  5  18  5  5  5  Amount of P in feed  g  0.0055  0.000191  0.00  0.02  0.00  0.00  0.01  Total P to start  g  3.01  0.82  2.96  6.00  3.77  7.46  3.68  Proportion of Mass P in feed  0.0018245  0.00023307  0.001592664  0.002993825  0.001220128  0.000628758  0.001451  Proportion of P in calcinated pellets  0.9981755  0.99976693  0.998407336  0.997006175  0.998779872  0.999371242  0.998549  END Uptake: struvite Conc P as PO4 Vol. sample  mg/L  19.8  35  20.4  23.6  23.5  23.3  0  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  43.9  40.2  42.8  41.8  37.4  38.8  0  Wt struvite after uptake  mg  30659.5  7361.8  27926.5  56265.5  24887  49176  0  Amount of P in struvite after uptake  mg  3457.05  1602.38  3327.69  7941.78  3909.39  7382.74  0.00  Amount of P in struvite after uptake  g  3.46  1.60  3.33  7.94  3.91  7.38  0.00  mg/L  42.6  0  23.7  26  18.3  18.9  19.4 0.25  Fines Conc P as PO4  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.8  0  41.6  41.9  36.3  37.4  40.3  Wt fines  mg  427.7  23.8  417  918.7  135.2  393.3  30001.5  Amount of P in fines  mg  114.45  0.00  59.39  142.52  17.04  49.69  3610.60  Amount of P in fines  g  0.11  0.00  0.06  0.14  0.02  0.05  3.61  Vol. sample  Filter Paper mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of P on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of P in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Conc P as PO4 Vol. sample  Feed 0 mins  mg/L  10.3  0  9.15  9.02  9.16  9.26  6390  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.0000515  0  0.00004575  0.0000451  0.0000458  0.0000463  0.03195  Conc P as PO4  151  Temperature: 80°C  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  12a  Sample  Unit  Conc P as PO4  pH 8  12b  12c pH 8  12d pH 8  15a pH 8  15b pH 9  15c pH 9  pH 9  mg/L  20.5  0  9.93  9.17  2.49  10.2  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.0001025  0  0.00004965  0.00004585  0.00001245  0.000051  0  mg/L  21.4  0  22.9  53.1  2.2  10.9  0  Conc P as PO4 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000107  0  0.0001145  0.0002655  0.000011  0.0000545  0  mg/L  20.9  0  26.2  63.4  2.19  11.2  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.0001045  0  0.000131  0.000317  0.00001095  0.000056  0  Conc P as PO4  mg/L  22.4  0  57  71.6  2.19  11.2  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000112  0  0.000285  0.000358  0.00001095  0.000056  0  Conc P as PO4  mg/L  23  0  29.7  75.2  2.24  11.5  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000115  0  0.0001485  0.000376  0.0000112  0.0000575  0  Conc P as PO4  mg/L  23  0  30.3  78.2  2.35  11.7  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000115  0  0.0001515  0.000391  0.00001175  0.0000585  0  Conc P as PO4  mg/L  24.3  0  31.6  83.4  2.47  13.6  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.0001215  0  0.000158  0.000417  0.00001235  0.000068  0  Conc P as PO4  mg/L  61  109  31.7  85.3  2.54  12.1  125  Vol. sample  L  0.46  0.49  0.46  0.46  0.46  0.46  0.567  Ammount of P in feed  g  0.02806  0.05341  0.014582  0.039238  0.0011684  0.005566  0.070875  TOTAL P AT END  g  3.60  1.66  3.40  8.13  3.93  7.44  3.71  Mass P remain in soln (g)  0.03  0.05  0.01  0.04  0.00  0.01  0.07  Mass in fines + filter (g)  0.11  0.00  0.06  0.14  0.02  0.05  3.61  Mass P in uptake pellets (g)  3.46  1.60  3.33  7.94  3.91  7.38  0.00  Mass P lost during sampling (g)  0.00  0.00  0.00  0.00  0.00  0.00  0.03  -0.59  -0.84  -0.44  -2.13  -0.16  0.02  -0.03  Reduction of mass in solution  -0.02  -0.05  -0.01  -0.02  0.00  0.00  -0.10  RECOVERY (%)  119  202  115  136  104  100  101  Conc P as PO4  DIFFERENCE  g  152  Table B. 24 2010 phosphorus balance 105°C Temperature: 105°C Sample  9a  9b  9c  10a  10b  10c  17a  17b  17c  Unit  pH 8  pH 8  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  32.7  32.7  32.7  36.6  36.6  36.6  29.5  29.5  29.5 0.25  START Roasted struvite Conc P as PO4  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41.2  41.2  41.2  38.4  38.4  38.4  35.4  35.4  35.4  Wt struvite for uptake  mg  20053.8  20026.6  20026  19950  19958  40551  19871  19911.7  39942.4  Amount of P in roasted struvite  mg  3979.12  3973.72  3973.61  4753.71  4755.62  9662.54  4139.79  4148.27  8321.33  Amount of P in roasted struvite  g  3.98  3.97  3.97  4.75  4.76  9.66  4.14  4.15  8.32  mg/L  8.68  8.94  8.72  9.74  1.21  9.56  10.1  10.7  10.3  L  0.5  0.5  0.5  0.5  0.5  0.5  0.6  0.5  0.5  Amount of P in feed  mg  4.34  4.47  4  5  1  5  6  5  5  Amount of P in feed  g  0.00434  0.00447  0.00  0.00  0.00  0.00  0.01  0.01  0.01  Total P to start  g  Vol. sample  Feed Conc P as PO4 Vol. sample  3.98  3.98  3.98  4.76  4.76  9.67  4.15  4.15  8.33  Proportion of Mass P in feed  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Proportion of P in calcinated pellets  1.00  1.00  1.00  1.00  1.00  1.00  1.00  1.00  1.00  mg/L  23.7  21.7  23.6  24.1  22.8  23.9  0  29.3  24.1  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41  39.2  41.2  38.3  39.2  38.2  0  43.6  40.7  Wt struvite after uptake  mg  29071.2  30211.9  26399.5  30497.1  30427.8  61526.8  0  24837.8  51166.7  Amount of P in struvite after uptake  mg  4201.14  4181.11  3780.51  4797.52  4424.45  9623.63  0.00  4172.86  7574.43  Amount of P in struvite after uptake  g  4.20  4.18  3.78  4.80  4.42  9.62  0.00  4.17  7.57  mg/L  19.5  19.8  19.8  22.1  7.62  20.5  25.4  12.3  19.7 0.25  END Uptake: struvite Conc P as PO4 Vol. sample  Fines Conc P as PO4  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  38.6  39  37.3  38  11.6  39.1  50.9  23  38.2  Wt fines  mg  391.2  516.7  45.8  507  34.5  1525  31605.3  120.4  234.8  Amount of P in fines  mg  49.41  65.58  6.08  73.72  5.67  199.89  3942.90  16.10  30.27  Amount of P in fines  g  0.05  0.07  0.01  0.07  0.01  0.20  3.94  0.02  0.03  0  0  0  0  0  0  Vol. sample  Filter Paper mg/L  0  0  0  L  0.05  0.05  0.05  Amount of P on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of P in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  mg/L  8.68  8.78  38.4  8.97  0  9.21  7300  10.7  10.1  Conc P as PO4 Vol. sample  Feed 0 mins  Conc P as PO4  153  Temperature: 105°C Sample  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  9a Unit  pH 8  9b  9c  pH 8  10a  pH 8  10b  pH 8  pH 8  10c pH 8  17a  17b  pH 9  17c  pH 9  pH 9  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  4.34E-05  4.39E-05  0.00019  4.49E-05  0  4.6E-05  0.0365  5.35E-05  5.05E-05  mg/L  46.9  70.6  0  87.3  0  139  0  3.36  3.6  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000235  0.000353  0  0.000437  0  0.0007  0  1.68E-05  0.000018  Conc P as PO4  mg/L  48.2  63.1  0  62.1  0  143  0  2.25  3.28  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000241  0.000316  0  0.000311  0  0.00072  0  1.13E-05  1.64E-05  Conc P as PO4  mg/L  50.9  56.8  0  54  0  158  0  2.1  3.08  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000255  0.000284  0  0.00027  0  0.00079  0  1.05E-05  1.54E-05  mg/L  54.4  58.1  0  55.7  0  169  0  2.06  3.18  Conc P as PO4  Conc P as PO4 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000272  0.000291  0  0.000279  0  0.00085  0  1.03E-05  1.59E-05  mg/L  56.2  61.6  0  57.3  0  174  0  2  3.14  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000281  0.000308  0  0.000287  0  0.00087  0  0.00001  1.57E-05  Conc P as PO4  mg/L  58.6  40.8  0  59.4  0  182  0  4.33  2.99  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000293  0.000204  0  0.000297  0  0.00091  0  2.17E-05  1.5E-05  Conc P as PO4  mg/L  61.4  68.3  0  59.9  0  189  0  2.25  2.97  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000307  0.000342  0  0.0003  0  0.00095  0  1.13E-05  1.49E-05  Conc P as PO4  mg/L  66.5  69.4  882.5  62  178  198  196  2.23  3.12  Vol. sample  L  0.46  0.46  0.46  0.46  0.49  0.46  0.56  0.46  0.46  Ammount of P in feed  g  0.03059  0.031924  0.40595  0.02852  0.08722  0.09108  0.10976  0.001026  0.001435  TOTAL P AT END  g  4.28  4.28  4.19  4.90  4.52  9.92  4.09  4.19  7.61  Mass P remain in soln  Conc P as PO4  g  0.03  0.03  0.41  0.03  0.09  0.09  0.11  0.00  0.00  Mass in fines + filter  g  0.05  0.07  0.01  0.07  0.01  0.20  3.94  0.02  0.03  Mass P in uptake pellets  g  4.20  4.18  3.78  4.80  4.42  9.62  0.00  4.17  7.57  Mass P lost during sampling  g  0.00  0.00  0.00  0.00  0.00  0.01  0.04  0.00  0.00  Reduction of mass in solution  g  -0.03  -0.03  -0.40  -0.03  -0.09  -0.09  -0.14  0.00  0.00  MASS BALANCE  g  -0.30  -0.30  -0.21  -0.14  0.24  -0.25  0.06  -0.04  0.72  108  108  105  103  95  103  99  101  91  RECOVERY (%)  154  Table B. 25 2010 phosphorus balance 160°C Temperature: 160°C Sample  11a  11b  11c  11d  16a  16b  16c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  28.5  28.5  28.5  0  31.5  31.5  31.5 0.25  START Roasted struvite Conc P as PO4  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  39.6  39.6  0  40.5  40.5  40.5  Wt struvite for uptake  mg  19910.7  40334.9  20472.3  0  19990.3  19962.3  39673.8  Amount of P in roasted struvite  mg  3582.42  7257.23  3683.46  0.00  3887.00  3881.56  7714.35  Amount of P in roasted struvite  g  3.58  7.26  3.68  0.00  3.89  3.88  7.71  mg/L  8.88  12.2  11.4  686  10.4  10.1  9.99  L  0.5  0.5  0.5  0.46  0.564  0.5  0.5  Amount of P in feed  mg  4.44  6.1  6  316  6  5  5  Amount of P in feed  g  0.00444  0.0061  0.01  0.32  0.01  0.01  0.00  Total P to start  g  3.59  7.26  3.69  0.32  3.89  3.89  7.72  Proportion of Mass P in feed  0.001238  0.0008398  0.0015451  1  0.001507  0.0013  0.00064708  Proportion of P in calcinated pellets  0.998762  0.9991602  0.9984549  0  0.998493  0.9987  0.99935292  mg/L  21.2  21.6  14.5  0  0  26.6  20.6  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  40  39.6  0  0  42.3  51.5  Wt struvite after uptake  mg  24809.6  50027.4  25818.7  0  0  24197.8  48258.1  Amount of P in struvite after uptake  mg  3320.48  6753.70  2363.45  0.00  0.00  3804.15  4825.81  Amount of P in struvite after uptake  g  3.32  6.75  2.36  0.00  0.00  3.80  4.83  mg/L  20.4  30.4  3.36  20.7  21.8  14.8  16.7  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Vol. sample  Feed Conc P as PO4 Vol. sample  END Uptake: struvite Conc P as PO4 Vol. sample  Fines Conc P as PO4 Vol. sample Wt sample for digesting  mg  40.3  58.5  38.3  40.6  51.2  29.4  32  Wt fines  mg  2315  5275.9  406.5  2206.6  29792.9  88.5  182.3  Amount of P in fines  mg  292.97  685.42  8.92  281.26  3171.31  11.14  23.78  Amount of P in fines  g  0.29  0.69  0.01  0.28  3.17  0.01  0.02  Filter Paper mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of P on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of P in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Conc P as PO4 Vol. sample  Feed 0 mins  mg/L  9.55  10.8  11.4  0  5910  10.1  10.2  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  4.78E-05  0.000054  0.000057  0  0.02955  5.1E-05  0.000051  Conc P as PO4  155  Temperature: 160°C 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  11a  Sample  Unit  Conc P as PO4  pH 8  11b pH 8  11c  11d  pH 8  16a  pH 8  16b  pH 9  16c  pH 9  pH 9  mg/L  236  165  523  22.4  0  14.4  17.3  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.00118  0.000825  0.002615  0.000112  0  7.2E-05  0.0000865  mg/L  93.2  146  571  16.5  0  8.94  12.7  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000466  0.00073  0.002855  8.25E-05  0  4.5E-05  0.0000635  Conc P as PO4  mg/L  94.3  150  583  0  0  7  10.7  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000472  0.00075  0.002915  0  0  3.5E-05  0.0000535  Conc P as PO4  mg/L  92.5  150  599  0  0  6.23  9.67  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000463  0.00075  0.002995  0  0  3.1E-05  0.00004835  Conc P as PO4  mg/L  90.1  149  621  0  0  5.61  8.87  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000451  0.000745  0.003105  0  0  2.8E-05  0.00004435  mg/L  87.4  156  622  0  0  5.29  8.11  Conc P as PO4  Conc P as PO4 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000437  0.00078  0.00311  0  0  2.6E-05  0.00004055  mg/L  83.8  178  630  0  0  5.28  7.99  Conc P as PO4 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of P in feed  g  0.000419  0.00089  0.00315  0  0  2.6E-05  0.00003995  7.46  mg/L  82.8  190  646  15.6  155  5.15  Vol. sample  L  0.46  0.46  0.46  0.44  0.554  0.46  0.46  Ammount of P in feed  g  0.038088  0.0874  0.29716  0.006864  0.08587  0.00237  0.0034316  TOTAL P AT END  g  Conc P as PO4  3.66  7.53  2.69  0.29  3.29  3.82  4.85  Mass P remain in soln (g)  0.04  0.09  0.30  0.01  0.09  0.00  0.00  Mass in fines + filter (g)  0.29  0.69  0.01  0.28  3.17  0.01  0.02  Mass P in uptake pellets (g)  3.32  6.75  2.36  0.00  0.00  3.80  4.83  Mass P lost during sampling (g)  0.00  0.01  0.02  0.00  0.03  0.00  0.00  -0.07  -0.27  1.00  0.03  0.61  0.07  2.87  Reduction of mass in solution  -0.04  -0.09  -0.31  0.31  -0.11  0.00  0.00  RECOVERY (%)  102  104  73  91  84  98  63  DIFFERENCE  g  156  Table B. 26 2010 magnesium balance 80°C 12a  Temperature: 80°C Sample  12b  12c  12d  15a  15b  15c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  18.92  18.92  18.92  18.92  27.284  27.284  27.284  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  40.7  40.7  40.7  40.7  47.3  47.3  47.3  Wt struvite for uptake  mg  20159.5  5489  19802.2  40048.3  20068.5  39729.1  19590  Amount of N in roasted struvite  mg  2342.86  637.91  2301.34  4654.26  2894.02  5729.22  2825.02  Amount of N in roasted struvite  g  2.34  0.64  2.30  4.65  2.89  5.73  2.83  mg/L  34.47  1.2825  31.1425  31.3875  30.6175  31.29  31.1375  L  0.5  0.5  0.5  0.5  0.5  0.5  0.577  START Roasted struvite Conc N as NH3 Vol. sample  Feed Conc N as NH3 Vol. sample Amount of N in feed  mg  17.235  0.64125  16  16  15  16  18  Amount of N in feed  g  0.017235  0.00064125  0.02  0.02  0.02  0.02  0.02  Total N to start  g  2.36  0.64  2.32  4.67  2.91  5.74  2.84  Proportion of Mass N in feed  0.0073027  0.001004225  0.006720703  0.003360578  0.005261949  0.002723301  0.00632  Proportion of N in calcinated pellets  0.9926973  0.998995775  0.993279297  0.996639422  0.994738051  0.997276699  0.99368  mg/L  15.889  26.106  16.642  16.227  17.5175  18.1975  0  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  END Uptake: struvite Conc N as NH3 Vol. sample Wt sample for digesting  mg  43.9  40.2  42.8  41.8  37.4  38.8  0  Wt struvite after uptake  mg  30659.5  7361.8  27926.5  56265.5  24887  49176  0  Amount of N in struvite after uptake  mg  2774.20  1195.19  2714.68  5460.65  2914.16  5765.98  0.00  Amount of N in struvite after uptake  g  2.77  1.20  2.71  5.46  2.91  5.77  0.00  mg/L  15.725556  0  18.04  19.893  13.899  14.684  14.8815 0.25  Fines Conc N as NH3 Vol. sample  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.8  0  41.6  41.9  36.3  37.4  40.3  Wt fines  mg  427.7  23.8  417  918.7  135.2  393.3  30001.5  Amount of N in fines  mg  42.25  0.00  45.21  109.04  12.94  38.60  2769.65  Amount of N in fines  g  0.04  0.00  0.05  0.11  0.01  0.04  2.77  Filter Paper Conc N as NH3  mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  mg/L  34.835  0  31.4475  31.205  30.8  31.045  5267.75  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  g  0.0001742  0  0.000157238  0.000156025  0.000154  0.000155225  0.026339  Vol. sample  Feed 0 mins  Conc N as NH3 Vol. sample Ammount of N in feed  157  12a  Temperature: 80°C 15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  Sample  Unit  pH 8  Conc N as NH3  12b  12c pH 8  12d  15a  15b  pH 8  pH 8  pH 9  15c pH 9  pH 9  mg/L  25.215  0  16  8.4275  14.3625  3.3  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0001261  0  0.00008  4.21375E-05  7.18125E-05  0.0000165  0  Conc N as NH3  mg/L  22.9025  0  14.29  8.1225  13.8125  3.1775  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0001145  0  0.00007145  4.06125E-05  6.90625E-05  1.58875E-05  0  Conc N as NH3  mg/L  21.8075  0  12.885  7.695  13.5675  3.1775  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.000109  0  0.000064425  0.000038475  6.78375E-05  1.58875E-05  0  Conc N as NH3  mg/L  21.8075  0  11.8475  6.9625  13.5675  2.995  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.000109  0  5.92375E-05  3.48125E-05  6.78375E-05  0.000014975  0  Conc N as NH3  mg/L  21.1975  0  11.175  6.84  14.055  3.1175  0  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.000106  0  0.000055875  0.0000342  0.000070275  1.55875E-05  0  mg/L  22.905  0  10.625  6.4725  14.3  3.055  0  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0001145  0  0.000053125  3.23625E-05  0.0000715  0.000015275  0  mg/L  21.3125  0  10.015  6.4775  14.055  4.725  0  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0001066  0  0.000050075  3.23875E-05  0.000070275  0.000023625  0  50.0375  Conc N as NH3  mg/L  51.1925  46.2875  9.5275  5.745  14.1775  3.3925  Vol. sample  L  0.46  0.49  0.46  0.46  0.46  0.46  0.567  Ammount of N in feed  g  0.0235486  0.022680875  0.00438265  0.0026427  0.00652165  0.00156055  0.028371  TOTAL N AT END  g  2.84  1.22  2.76  5.57  2.93  5.81  2.82  Mass N remain in soln (g)  0.02  0.02  0.00  0.00  0.01  0.00  0.03  Mass in fines + filter (g)  0.04  0.00  0.05  0.11  0.01  0.04  2.77  Mass N in uptake pellets (g)  2.77  1.20  2.71  5.46  2.91  5.77  0.00  Mass N lost during sampling (g)  0.00  0.00  0.00  0.00  0.00  0.00  0.03  -0.48  -0.58  -0.45  -0.90  -0.02  -0.06  0.02  Reduction of mass in solution  -0.01  -0.02  0.01  0.01  0.01  0.01  -0.04  RECOVERY (%)  120  191  119  119  101  101  99  DIFFERENCE  g  158  Table B. 27 2010 magnesium balance 105°C Temperature: 105°C Sample  9a  9b  9c  10a  10b  10c  17a  17b  17c  Unit  pH 8  pH 8  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  27.2885  27.2885  27.2885  25.666  25.666  25.666  23.0418  23.04175  23.0418 0.25  START Roasted struvite Conc N as NH3  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41.2  41.2  41.2  38.4  38.4  38.4  35.4  35.4  35.4  Wt struvite for uptake  mg  20053.8  20026.6  20026  19950  19958  40551  19871  19911.7  39942.4  Amount of N in roasted struvite  mg  3320.62  3316.12  3316.02  3333.57  3334.91  6775.92  3233.49  3240.12  6499.60  Amount of N in roasted struvite  g  3.32  3.32  3.32  3.33  3.33  6.78  3.23  3.24  6.50  mg/L  31.29  31.29  32.8525  30.7775  0  30.8375  30.386  32.00723  31.191  L  0.5  0.5  0.5  0.5  0.5  0.5  0.6  0.5  0.5  Amount of N in feed  mg  15.645  15.645  16  15  0  15  18  16  16  Amount of N in feed  g  0.015645  0.015645  0.02  0.02  0.00  0.02  0.02  0.02  0.02  Total N to start  g  Vol. sample  Feed Conc N as NH3 Vol. sample  3.34  3.33  3.33  3.35  3.33  6.79  3.25  3.26  6.52  Proportion of Mass N in feed  0.00  0.00  0.00  0.00  0.00  0.00  0.01  0.00  0.00  Proportion of N in calcinated pellets  1.00  1.00  1.00  1.00  1.00  1.00  0.99  1.00  1.00  mg/L  17.9267  16.5768  18.481649  17.17629  17.433299  16.76299  0  37.74607  19.2385  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  41  39.2  41.2  38.3  39.2  38.2  0  43.6  40.7  Wt struvite after uptake  mg  29071.2  30211.9  26399.5  30497.1  30427.8  61526.8  0  24837.8  51166.7  Amount of N in struvite after uptake  mg  3177.75  3193.98  2960.60  3419.24  3383.02  6749.82  0.00  5375.74  6046.49  Amount of N in struvite after uptake  g  3.18  3.19  2.96  3.42  3.38  6.75  0.00  5.38  6.05  mg/L  14.4161  14.7172  15.397113  14.82763  5.2668041  15.10485  19.0779  9.76896  14.743 0.25  END Uptake: struvite Conc N as NH3 Vol. sample  Fines Conc N as NH3  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  38.6  39  37.3  38  11.6  39.1  50.9  23  38.2  Wt fines  mg  391.2  516.7  45.8  507  34.5  1525  31605.3  120.4  234.8  Amount of N in fines  mg  36.53  48.75  4.73  49.46  3.92  147.28  2961.50  12.78  22.65  Amount of N in fines  g  0.04  0.05  0.00  0.05  0.00  0.15  2.96  0.01  0.02  0  0  0  0  0  0  Vol. sample  Filter Paper mg/L  0  0  0  L  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  mg/L  30.6775  30.0675  43.6  30.41  0  30.655  1428.25  31.23025  32.0592  Conc N as NH3 Vol. sample  Feed 0 mins  Conc N as NH3  159  Temperature: 105°C Sample  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  9a Unit  pH 8  9b  9c pH 8  10a pH 8  10b  10c  pH 8  pH 8  pH 8  17a  17b  pH 9  pH 9  17c pH 9  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.000153  0.0001503  0.000218  0.000152  0  0.000153  0.00714  0.000156  0.00016 13.6194  mg/L  18.5775  39.905  0  57.4  0  26.135  0  17.77938  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  9.29E-05  0.0001995  0  0.000287  0  0.000131  0  8.89E-05  6.8E-05 12.6474  Conc N as NH3  mg/L  15.155  30.6775  0  35.1725  0  16.1225  0  16.71673  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  7.58E-05  0.0001534  0  0.000176  0  8.06E-05  0  8.36E-05  6.3E-05 12.4661  Conc N as NH3  mg/L  13.69  22.9775  0  25.8925  0  15.51  0  16.48353  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  6.85E-05  0.0001149  0  0.000129  0  7.76E-05  0  8.24E-05  6.2E-05  mg/L  12.7125  19.0675  0  25.16  0  17.045  0  16.53494  12.3108  Conc N as NH3  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  6.36E-05  9.534E-05  0  0.000126  0  8.52E-05  0  8.27E-05  6.2E-05  mg/L  11.49  18.2125  0  22.5325  0  14.7075  0  15.83534  12.57  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  5.75E-05  9.106E-05  0  0.000113  0  7.35E-05  0  7.92E-05  6.3E-05 12.4921  Conc N as NH3  mg/L  9.7775  16.3775  0  21.3725  0  14.7075  0  17.98661  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  4.89E-05  8.189E-05  0  0.000107  0  7.35E-05  0  8.99E-05  6.2E-05 12.1291  Conc N as NH3  mg/L  10.145  15.8275  0  20.2725  0  14.4625  0  16.71673  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  5.07E-05  7.914E-05  0  0.000101  0  7.23E-05  0  8.36E-05  6.1E-05  mg/L  9.045  15.645  595.7  19.0525  78.53  14.7075  3.595  16.56091  11.9218  Conc N as NH3  Conc N as NH3 Vol. sample  L  0.46  0.46  0.46  0.46  0.49  0.46  0.56  0.46  0.46  Ammount of N in feed  g  0.004161  0.0071967  0.274022  0.008764  0.0384797  0.006765  0.00201  0.007618  0.00548  TOTAL N AT END  g  3.22  3.25  3.24  3.48  3.43  6.90  2.97  5.40  6.08  Mass N remain in soln  g  0.00  0.01  0.27  0.01  0.04  0.01  0.00  0.01  0.01  Mass in fines + filter  g  0.04  0.05  0.00  0.05  0.00  0.15  2.96  0.01  0.02  Mass N in uptake pellets  g  3.18  3.19  2.96  3.42  3.38  6.75  0.00  5.38  6.05  Mass N lost during sampling  g  0.00  0.00  0.00  0.00  0.00  0.00  0.01  0.00  0.00  Reduction of mass in solution  g  0.01  0.01  -0.26  0.01  -0.04  0.01  0.01  0.01  0.01  MASS BALANCE  g  0.12  0.08  0.09  -0.13  -0.09  -0.11  0.28  -2.14  0.44  96  98  97  104  103  102  91  166  93  RECOVERY (%)  160  Table B. 28 2010 magnesium balance 160°C Temperature: 160°C Sample  11a  11b  11c  11d  16a  16b  16c  Unit  pH 8  pH 8  pH 8  pH 8  pH 9  pH 9  pH 9  mg/L  26.253  26.253  26.253  0  24.80612  24.80612  24.80612 0.25  START Roasted struvite Conc N as NH3  L  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  39.6  39.6  0  40.5  40.5  40.5  Wt struvite for uptake  mg  19910.7  40334.9  20472.3  0  19990.3  19962.3  39673.8  Amount of N in roasted struvite  mg  3299.97  6685.05  3393.05  0.00  3061.00  3056.71  6075.02  Amount of N in roasted struvite  g  3.30  6.69  3.39  0.00  3.06  3.06  6.08  mg/L  30.215  33.025  33.33  528.48  31.5815  30.824  30.5795  L  0.5  0.5  0.5  0.46  0.564  0.5  0.5  Amount of N in feed  mg  15.1075  16.5125  17  243  18  15  15  Amount of N in feed  g  0.0151075  0.0165125  0.02  0.24  0.02  0.02  0.02  Total N to start  g  3.32  6.70  3.41  0.24  3.08  3.07  6.09  Proportion of Mass N in feed  0.0045572  0.00246398  0.0048875  1  0.00578534  0.00501673  0.0025105  Proportion of N in calcinated pellets  0.9954428  0.99753602  0.9951125  0  0.99421466  0.99498327  0.9974895  mg/L  19.453  19.868  16.4588889  0  0  21.32826  17.36439  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Wt sample for digesting  mg  39.6  40  39.6  0  0  42.3  51.5  Wt struvite after uptake  mg  24809.6  50027.4  25818.7  0  0  24197.8  48258.1  Amount of N in struvite after uptake  mg  3046.85  6212.15  2682.75  0.00  0.00  3050.22  4067.83  Amount of N in struvite after uptake  g  3.05  6.21  2.68  0.00  0.00  3.05  4.07  mg/L  15.787  22.434  0.21777778  19.5011111  17.92672  10.971  13.29823  L  0.25  0.25  0.25  0.25  0.25  0.25  0.25  Vol. sample  Feed Conc N as NH3 Vol. sample  END Uptake: struvite Conc N as NH3 Vol. sample  Fines Conc N as NH3 Vol. sample Wt sample for digesting  mg  40.3  58.5  38.3  40.6  51.2  29.4  32  Wt fines  mg  2315  5275.9  406.5  2206.6  29792.9  88.5  182.3  Amount of N in fines  mg  226.72  505.81  0.58  264.97  2607.86  8.26  18.94  Amount of N in fines  g  0.23  0.51  0.00  0.26  2.61  0.01  0.02  Filter Paper mg/L  0  0  0  0  0  0  0  L  0.05  0.05  0.05  0.05  0.05  0.05  0.05  Amount of N on filter paper  mg  0.00  0.00  0.00  0.00  0.00  0.00  0.00  Amount of N in filter paper  g  0.00  0.00  0.00  0.00  0.00  0.00  0.00  30.5795  Conc N as NH3 Vol. sample  Feed 0 mins  mg/L  31.3225  31.19  33.33  0  3605.5  30.9215  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0001566  0.00015595  0.00016665  0  0.0180275  0.00015461  0.0001529  Conc N as NH3  161  Temperature: 160°C  15 mins  30 mins  45 mins  60 mins  75 mins  90 mins  105 mins  120 mins  11a  11b  11c  11d  16a  Sample  Unit  pH 8  pH 8  pH 8  pH 8  Conc N as NH3  16b  16c  pH 9  pH 9  pH 9 43.8035  mg/L  183.445  105.065  436.7675  12.9175  0  39.5015  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0009172  0.00052533  0.00218384  6.4588E-05  0  0.00019751  0.00021902  mg/L  80.43  106.2875  485.445  8.1675  0  35.5905  40.5035  Conc N as NH3 Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0004022  0.00053144  0.00242723  4.0838E-05  0  0.00017795  0.00020252  mg/L  86.83  103.72  496.575  0  0  33.977  39.4525  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0004342  0.0005186  0.00248288  0  0  0.00016989  0.00019726 37.9615  Conc N as NH3  mg/L  87.02  96.015  493.64  0  0  33.6595  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0004351  0.00048008  0.0024682  0  0  0.0001683  0.00018981 37.7415  Conc N as NH3  mg/L  82.9875  87.575  491.9275  0  0  35  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0004149  0.00043788  0.00245964  0  0  0.000175  0.00018871 37.096  Conc N as NH3  mg/L  77.61  89.9  485.69  0  0  125.46  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0003881  0.0004495  0.00242845  0  0  0.0006273  0.00018548  Conc N as NH3  mg/L  73.0275  98.8275  494.375  0  0  32.2905  36.6165  Vol. sample  L  0.005  0.005  0.005  0.005  0.005  0.005  0.005  Ammount of N in feed  g  0.0003651  0.00049414  0.00247188  0  0  0.00016145  0.00018308 35.9935  Conc N as NH3  mg/L  71.6225  103.5975  496.085  8.9  136.8325  32.486  Vol. sample  L  0.46  0.46  0.46  0.44  0.554  0.46  0.46  Ammount of N in feed  g  0.0329464  0.04765485  0.2281991  0.003916  0.07580521  0.01494356  0.01655701  TOTAL N AT END  g  3.31  6.77  2.93  0.27  2.70  3.08  4.10  Mass N remain in soln (g)  0.03  0.05  0.23  0.00  0.08  0.01  0.02  Mass in fines + filter (g)  0.23  0.51  0.00  0.26  2.61  0.01  0.02  Mass N in uptake pellets (g)  3.05  6.21  2.68  0.00  0.00  3.05  4.07  Mass N lost during sampling (g)  0.00  0.00  0.02  0.00  0.02  0.00  0.00  0.01  -0.07  0.48  -0.03  0.38  0.00  1.99  Reduction of mass in solution  -0.02  -0.03  -0.23  0.24  -0.08  0.00  0.00  RECOVERY (%)  100  101  86  111  88  100  67  Conc N as NH3  DIFFERENCE  g  162  Appendix C: Elemental analysis spreadsheet Table C. 1 Elemental analysis solver  user input %N user input %H %N + %H (from input) Mass of MgHPO4  = = = =  0.053 0.064 0.117 120.286  Solve%N Equation (Eqn 14) Solve %H Equation (Eqn 15) %N + %H (output) Input = output= ? X solved (amount N) Y solved (amount H2O)  = = = = = =  0.053 0.064 0.117 YES 0.902 5.705  <=go to target cell <=go to target cell <= Target cell soln  163  Appendix D: Mass balance graphs  0.50 0.40  mass (g)  0.30  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.20 0.10 0.00 -0.10  8  9  10  -0.20 pH  -0.30  Figure D. 1 2009 nitrogen mass balance @ T=100 for pH 8,9,10  0.50 0.40 0.30 mass (g)  0.20  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.10 0.00 -0.10  8  9  10  -0.20 -0.30  pH  Figure D. 2 2009 nitrogen mass balance @ T=120 for pH 8,9,10  164  0.50 0.40 0.30 mass (g)  0.20  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.10 0.00 -0.10  8  9  10  -0.20 pH  -0.30  Figure D. 3 2009 nitrogen mass balance @ T=140 for pH 8,9,10  0.50 0.40  mass (g)  0.30 N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.20 0.10 0.00 -0.10  8  9  10  -0.20 -0.30  pH  Figure D. 4 2009 nitrogen mass balance @ T=160 for pH 8,9,10  165  0.50 0.40 0.30  mass (g)  0.20 0.10 0.00 -0.10  8  9  10  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  -0.20 -0.30  pH  Figure D. 5 2009 nitrogen mass balance @ T=180 for pH 8,9,10  0.50 0.40 0.30 mass (g)  0.20  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.10 0.00 -0.10  8  9  10  -0.20 -0.30  pH  Figure D. 6 2009 nitrogen mass balance @ T=200 for pH 8,9,10  166  2.40 1.90 1.40 mass (g)  0.90 0.40 -0.10 8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -0.60 -1.10 -1.60  pH  Figure D. 7 2009 phosphorus mass balance @ T=100 for pH 8,9,10  2.40 1.90 1.40  mass (g)  0.90 0.40 -0.10 -0.60  8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -1.10 -1.60  pH  Figure D. 8 2009 phosphorus mass balance @ T=120 for pH 8,9,10  167  2.40 1.90 1.40  mass (g)  0.90 0.40 -0.10 8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -0.60 -1.10 -1.60  pH  Figure D. 9 2009 phosphorus mass balance @ T=140 for pH 8,9,10  2.40 1.90 1.40 mass (g)  0.90 0.40 -0.10 -0.60  8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -1.10 -1.60  pH  Figure D. 10 2009 phosphorus mass balance @ T=160 for pH 8,9,10  168  2.40 1.90 1.40 mass (g)  0.90 0.40 -0.10 -0.60  8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -1.10 -1.60  pH  Figure D. 11 2009 phosphorus mass balance @ T=180 for pH 8,9,10  2.40 1.90  mass (g)  1.40 0.90 0.40 -0.10 -0.60  8  9  10  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  -1.10 -1.60  pH  Figure D. 12 2009 phosphorus mass balance @ T=200 for pH 8,9,10  169  1.00 0.90 0.80 0.70 mass (g)  0.60  Mg loss in solution (g)  0.50 0.40  Mg in fines + filter (g)  0.30 0.20 0.10 0.00 8  9 pH  10  Figure D. 13 2009 magnesium mass balance @ T=100 for pH 8,9,10  1.90 0.90  mass (g)  -0.10 -1.10  8  9  10  -2.10  Mg loss in solution (g) Mg in fines + filter (g)  -3.10 -4.10 -5.10  pH  Figure D. 14 2009 magnesium mass balance @ T=120 for pH 8,9,10  170  1.90 0.90  mass (g)  -0.10 -1.10  8  9  10  Mg loss in solution (g) Mg in fines + filter (g)  -2.10 -3.10 -4.10 -5.10  pH  Figure D. 15 2009 magnesium mass balance @ T=140 for pH 8,9,10  1.90 0.90 -0.10 mass (g)  8  9  10  -1.10 -2.10  Mg loss in solution (g) Mg in fines + filter (g)  -3.10 -4.10 -5.10  pH  Figure D. 16 2009 magnesium mass balance @ T=160 for pH 8,9,10  171  1.90 0.90 -0.10 mass (g)  8  9  10  -1.10  Mg loss in solution (g) Mg in fines + filter (g)  -2.10 -3.10 -4.10 -5.10  pH  Figure D. 17 2009 magnesium mass balance @ T=180 for pH 8,9,10  1.90 0.90 -0.10 mass (g)  8  9  10  -1.10  Mg loss in solution (g) Mg in fines + filter (g)  -2.10 -3.10 -4.10 -5.10  pH  Figure D. 18 2009 magnesium mass balance @ T=200 for pH 8,9,10  172  0.50 0.40  mass (g)  0.30 N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.20 0.10 0.00 12a  -0.10  12b  12c  12d  15a  15b  15c  -0.20 pH -0.30 Figure D. 19 2010 nitrogen mass balance @ T=80  0.50 0.40  mass (g)  0.30  N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.20 0.10 0.00 -0.10 -0.20  9a  9b  9c  10a  10b  10c  17a  17b  17c  pH  -0.30 Figure D. 20 2010 nitrogen mass balance @ T=105  173  0.50 0.40  mass (g)  0.30 N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  0.20 0.10 0.00 -0.10  11a  11b  11c  11d  16a  16b  16c  -0.20 -0.30  pH  Figure D. 21 2010 nitrogen mass balance @ T=160  0.50 0.40 0.30 mass (g)  0.20  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  0.10 0.00 -0.10  12a  12b  12c  12d  15a  15b  15c  -0.20 -0.30  pH  Figure D. 22 2010 phosphorus mass balance @ T=80  174  0.50 0.40  mass (g)  0.30  P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  0.20 0.10 0.00 -0.10  9a  9b  9c  10a  10b  10c  17a  17b  17c  -0.20 pH  -0.30  Figure D. 23 2010 phosphorus mass balance @ T=105  0.50 0.40  mass (g)  0.30 P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  0.20 0.10 0.00 -0.10  11a  11b  11c  11d  16a  16b  16c  -0.20 -0.30  pH  Figure D. 24 2010 phosphorus mass balance @ T=160  175  0.50 0.40  mass (g)  0.30 0.20  Mg loss in solution (g)  0.10  Mg in fines + filter (g)  0.00 -0.10  12a  12b  12c  12d  15a  15b  15c  -0.20 pH  -0.30  Figure D. 25 2010 magnesium mass balance @ T=80  0.50 0.40  mass (g)  0.30  Mg loss in solution (g)  0.20 Mg in fines + filter (g) 0.10 0.00 -0.10  9a  9b  9c  10a  10b  10c  17a  17b  17c  -0.20 pH -0.30 Figure D. 26 2010 magnesium mass balance @ T=105  176  0.50 0.40  mass (g)  0.30 Mg loss in solution (g)  0.20 0.10  Mg in fines + filter (g)  0.00 -0.10  11a  11b  11c  11d  16a  16b  16c  -0.20 -0.30  pH  Figure D. 27 2010 magnesium mass balance @ T=160  177  Appendix E: Economic analysis Table E. 1 Heating-reformation method  Struvite price ($/tonne) Struvite price ($/gram) initial mass (g) mass after heat (g) mass after uptake (g) Mass used per experiment (g) Total Struvite cost per batch ($/batch) volume centrate per batch (L/batch) Cost per litre ($/litre) Total volume wastewater per day (MLD) BOD removed per day (lb/ML) Total volume centrate treated per day (L/Day) Sludge specific gravity water unit weight (lb/ft3) BOD utilization rate (lb cells/lb BOD utilized) Volume sludge (cubic feet per day) volume centrate per volume sludge Volume centrate (liters per day) Cost per day ($/day)  3000 0.003 50 28.5 43.3 5.2 0.01554 0.5 0.03108 76.2 548.5986  Caustic price ($/kg) Caustic usage (kg/L) Caustic price ($/L treated) Total caustic price per day ($/day)  0.5 0.005773 0.002887 805.3043  Electricity price ($/kwh) Power per volume (hp/L) power per volume (kilowatts/L) efficiency (%) power drawn per day per litre Daily power drawn per litre (kwh/day/l) Daily Electricity cost ($/day)  0.02817 0.033333 0.02486 0.9 0.03 0.03 217.07  Labour Cost Total Cost per day ($/day)  54000 1.02 62.4 0.05 13135.75 0.75 278973.8 8670.505  120.55 9813  178  Table E. 2 Sidestream nitrification method  centrate NH3 conc (mg/L) desired NH3 effluent conc (mg/L) NH3 removal desired (mg/L) molar mass NH3 molar mass N N removal desired (mg/L) alkalinity consumption (eq CaCO3/mol N) total alkalinity required (mg/L as CaCO3) alkalinity in centrate (mg/L as CaCO3) alkalinity addition required (mg/L as CaCO3) Flow treated (L/day) daily mass CaCO3 requirmennt (kg/day) price CaCO3 ($/kg) Daily alkalinity cost ($/day) oxygen requirement (kg/day) oxygen price ($/kg) Daily oxygen cost ($/day) Total Cost per day ($/day)  700 5 695 17 14 572.3529 2 4088.235 100 3988.235 278973.8 1112.613 0.3 334 1620 0.2 324 658  179  

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