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Ammonia removal and recovery using heated struvite as an adsorbent 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  ii  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  iii  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.    iv  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 31 P Magic angle spinning nuclear magnetic resonance ( 31 P 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  v  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  vi  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  vii  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   viii  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  ix  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  x  Table E. 2 Sidestream nitrification method .................................................................... 179    xi  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  xii  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  xiii  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  xiv  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 PO4 3-  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 PO4 3- concentration. ............................................... 82 Figure 68 Effect of no pH control on Mg 2+  concentration. ............................................... 82  xv  Figure 69 NH4 +  concentration vs. time at pH 9. ............................................................... 83 Figure 70 PO4 3-  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  xvi  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  xvii  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    xviii  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.  1  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 non- compliance with nutrient discharge limits.   2  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  3  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 $3000 USD per tonne (Mavinic, 2010). Thus, nutrient recovery benefits both the environment and the process integrity, while providing a significant revenue stream for the treatment plant owners.  Table 1 Struvite benefit comparison case studies. Treatment Plant Flow Influent P Influent N P removal N removal P load reduction N load reduction Struvite Prod. Yearly Rev.  mgd (mg/L) (mg/L) (%) (%) (%) (%) (t/yr) ($ mill) Gold Bar 68.7 207 805 75 20 20 5 1200 3.6 Nansemond 18.3 140- 700 500- 800 80 42 30 10 1650 4.9 Durham 20 600 1200 95 19 24 6 430 1.3 Penticton 5.6 37-71 197- 436 91 10 N/A N/A N/A N/A Lulu Island 21.1 39-88 410- 907 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 m 3 , the capital and operating costs become too high (Stefanowicz et al., 1992). A sustainable approach,  4  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.   2009 2010 Component Concentration Molar ratio Concentration Molar ratio N 300 mg/L N:P = 65:1 700 mg/L N:P = 150:1 P 10 mg/L Mg:P = 37:1 10 mg/L Mg:P = 37:1 Mg 30 mg/L N:Mg = 4.2:1 30 mg/L N:Mg = 4.2:1  5  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.   6  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 (HPO4 2- ), and orthophosphate (PO4 3- ). 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 (Mg 2+●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). Mg 2+  + NH4 +  + HPO4 2-  + OH -  + 5H2O  MgNH4PO4●6H20 (Equation 2) Mg 2+  + NH4 +  + H2PO4 -  + 2OH -  + 4H2O  MgNH4PO4●6H20 (Equation 3)    7  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.  8  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  9  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 100-  10  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,  11  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 heat- transfer. 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)  12  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  13  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.   14  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 Content of NH4 +  (°C) (%) 50 2.7 100 1.2  15  Heating temperature Content of NH4 +  (°C) (%) 150 0.4 250 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 31 P 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  16  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)  17  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 dissolution- precipitation. 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.  18  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.    19  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.  20   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:  21  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 Part 1: 2009 Part 2: 2010 Mg 30 30 N 300 700 P 10 10 pH 6.63-7.08 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  22  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.  23  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.    24  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”  25  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  26  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.   27  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  28  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.   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 0 10 20 30 40 50 60 70 80 90 100 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 P e rc e n t m as s re m ai n in g Heating temperature (°C) TGA curve Theoretical percent mass remaining 24 hour isothermal treatments  29  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  30  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.  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 Percent mass recovery 40 -0.7 60 1.1 80 13.3 105 18.0 160 25.3 200 25.4  Table 6 Theoretical bulk sample identity after exposure to atmospheric moisture. Bulk Identity Mass remaining Two week water gain MgHPO4 49% No water gain MgHPO4●1H2O 56% 1 water gain MgHPO4●2H2O 64% 2 water gain MgHPO4●3H2O 71% 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 40% 50% 60% 70% 80% 90% 100% 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 P e rc e n t m as s re m ai n in g Time (hours) 40 60 80 105 160 200 Theoretical  31  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.   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 24.8 25 25.2 25.4 25.6 25.8 26 26.2 26.4 26.6 26.8 0 10 20 30 40 50 60 m as s (g ) Time (hours) mass in dessicator mass when exposed to air  32  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.   Figure 6 Nitrogen content immediately after heating compared to after two weeks exposed to the atmosphere for six different temperatures and 24 hour duration. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Control 40 60 80 105 160 200 M o le s o f n it ro ge n Heating temperature (°C) Nitrogen content immediately after heat Nitrogen content after two weeks  33  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.  34   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 Observed loss Calculated loss Possible chemical formula Room “control” N/A 1.1% MgHPO4(NH3)0.95(H2O)5.90 40 0.4% 1.5% MgHPO4(NH3)0.96(H2O)5.84 60 3.3% 8.9% MgHPO4(NH3)0.82(H2O)4.97 80 39.5% 41.7% MgHPO4(NH3)0.28(H2O)1.00 105 45.2% 43.7% MgHPO4(NH3)0.31(H2O)0.70 160 49.3% 47.4% MgHPO4(NH3)0.19(H2O)0.31 200 51.2% 48.8% MgHPO4(NH3)0.13(H2O)0.18  0 1 2 3 4 5 6 Control 40 60 80 105 160 200 M o le s o f w at e r Heating temperature (°C) Water content immediately after heat Water content after two weeks  35  Table 8 Observed and calculated mass loss and possible chemical formula two weeks after heating and exposure to the atmosphere. Temperature Observed loss Calculated loss Possible chemical formula Room “control” N/A 1.1% MgHPO4(NH3)0.95(H2O)5.90 40 0.7% 2.8% MgHPO4(NH3)0.90(H2O)5.71 60 2.2% 6.2% MgHPO4(NH3)0.78(H2O)5.36 80 31.4% 32.3% MgHPO4(NH3)0.26(H2O)2.30 105 35.4% 35.1% MgHPO4(NH3)0.31(H2O)1.87 160 36.5% 36.6% MgHPO4(NH3)0.16(H2O)1.80 200 38.8% 39.5% 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.   Figure 8 Effect of heating temperature on struvite nitrogen content for three different environments.  0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 80 105 160 Fr ac ti o n al  m o le s o f n it ro ge n Heating temperature (°C) Immediately after heat 24 hours after heat Rehydration after heat  36  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 re- attain a molar water value of six because of the very short reaction period.   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 0 0.5 1 1.5 2 2.5 3 3.5 4 80 105 160 M o le s o f w at e r Heating temperature (°C) Immediately after heat 24 hours after heat Rehydration after heat  37  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 nitrogen content in the fines that was close to the theoretical struvite value of one.   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.  0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Immediately after heat 24 hours after heat Rehydration after heat Batch rehydration after heat Uptake pH 8, 40g Fines pH 8, 40g Fr ac ti o n al  m o le s o f n it ro ge n  38   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 Possible chemical formula Heated struvite MgHPO4(NH3)0.31(H2O)0.70 Heated struvite after 24 hours exposure MgHPO4(NH3)0.31(H2O)1.87 Rehydration in DI H2O MgHPO4(NH3)0.26(H2O)4.12 Uptake MgHPO4(NH3)0.36(H2O)4.27 Fines 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, 0 1 2 3 4 5 6 Immediately after heat 24 hours after heat Rehydration after heat Batch rehydration after heat Uptake pH 8, 40g Fines pH 8, 40g M o le s o f w at e r  39  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).   40   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.    Figure 13 N:Mg ratio comparison of pellets immediately after heating and after 2 weeks exposure to atmospheric moisture. 0 0.2 0.4 0.6 0.8 1 1.2 40 60 80 105 160 200 N :P  r at io Heating temperature (°C) Immediately after heating After 2 weeks atmospheric exposure 0 0.2 0.4 0.6 0.8 1 1.2 40 60 80 105 160 200 N :M g Heating temperature (°C) Immediately after heating After 2 weeks atmospheric exposure  41  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.   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. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 40 60 80 105 160 200 M g: P Heating temperature (°C) Immediately after heating After 2 weeks atmospheric exposure  42  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.   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 50 51 52 53 54 55 56 57 58 59 80 100 105 120 140 160 180 200 P e rc e n t m as s re m ai n in g Heating temperature (°C)  43  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.   Figure 16 Percent mass remaining versus time comparing size and morphology at a heating temperature of 100°C.  Figure 17 Percent mass remaining versus time comparing size and morphology at a heating temperature of 110°C. 0 10 20 30 40 50 60 70 80 90 100 0 6 12 18 24 %  m as s re m ai n in g Heating time (hours) AB-100 whole AB-100 crushed AB-110 crushed AB-110 whole % theoretical remaining 0 10 20 30 40 50 60 70 80 90 100 0 6 12 18 24 %  m as s re m ai n in g Heating time (hours) AB-110 whole AB-110 crushed Lulu-110 whole Lulu-110 crushed  44   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 0.3- 0.4 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 0 10 20 30 40 50 60 70 80 90 100 0 6 12 18 24 %  m as s re m ai n in g Heating time (hours) AB-120 whole AB-120 crushed Lulu-120 whole Lulu-120 crushed  45  remainder of ammonia. This has important implications with respect to energy cost savings associated with heating struvite to remove ammonia.   Figure 19 Mg:P vs. heating time for four temperatures.  Figure 20 N:P vs. heating time for four temperatures. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 0 1 2 3 4 5 6 M g: P Heating time (hours) 100 110 120 140 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 0 1 2 3 4 5 6 N :P Heating time (hours) 100 110 120 140  46   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. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0 1 2 3 4 5 6 M g: N Heating time (hours) 100 110 120 140  47  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.   Figure 22 Ammonia concentration for Gold Bar struvite at pH 8. 0 50 100 150 200 250 300 350 0 15 30 45 60 75 90 105 120 A m m o n ia  ( m g/ L) Time (Minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  48  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.   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%. 0 50 100 150 200 250 300 350 0 15 30 45 60 75 90 105 120 A m m o n ia  ( m g/ L) Time (Minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  49    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. 0 50 100 150 200 250 300 350 0 15 30 45 60 75 90 105 120 A m m o n ia  ( m g/ L) Time (Minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  50  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.   Figure 25 Orthophosphate concentration for Gold Bar struvite at pH 8. 0 50 100 150 200 250 300 350 400 450 500 0 15 30 45 60 75 90 105 120 P h o sp h at e  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  51  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 ammonium to form new struvite.   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.  0 50 100 150 200 250 300 350 400 450 500 0 15 30 45 60 75 90 105 120 P h o sp h at e  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  52   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. 0 50 100 150 200 250 300 350 400 450 500 0 15 30 45 60 75 90 105 120 P h o sp h at e  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  53  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.    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 0.00 50.00 100.00 150.00 200.00 250.00 300.00 0 15 30 45 60 75 90 105 120 M ag an is u m  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  54  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.   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).  0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 0 15 30 45 60 75 90 105 120 M ag an is u m  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  55   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. 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 0 15 30 45 60 75 90 105 120 M ag an is u m  ( m g/ L) Time (minutes) Temp 100C Temp 120C Temp 140C Temp 160C Temp 180C Temp 200C  56  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.   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 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 0 20 40 60 80 100 120 140 SS R Time (minutes) 100 120 140 160 180 200  57  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.  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 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 0 20 40 60 80 100 120 140 SS R Time (minutes) 100 120 140 160 180 200  58  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.   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 0.0 20.0 40.0 60.0 80.0 100.0 120.0 0 20 40 60 80 100 120 140 SS R Time (minutes) 100 120 140 160 180 200  59  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.   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 0 2 4 6 8 10 12 14 16 18 100 120 140 160 180 200 %  F in e s p ro d u ce d Heating temperature (°C) 8 9 10  60  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.   Figure 35 Volume NaOH used vs. time for pH 8.   Figure 36 Volume NaOH used vs. time for pH 9.   0.0 5.0 10.0 15.0 20.0 25.0 30.0 0 20 40 60 80 100 120 m m o l N aO H Time (minutes) 100 120 140 160 180 200 0.0 5.0 10.0 15.0 20.0 25.0 30.0 0 20 40 60 80 100 120 m m o l N aO H Time (minutes) 100 140 160 180 200  61   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.  0.0 5.0 10.0 15.0 20.0 25.0 30.0 0 20 40 60 80 100 120 m m o l N aO H Time (minutes) 100 120 140 160 180 200  62   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 semi- quantitatively 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 0 5 10 15 20 25 30 35 40 45 100 120 140 160 180 200 m m o l N aO H Temperature (°C) 8 9 10  63  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.   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.  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. 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Roasted N:P Uptake N:P Fines N:P N :P 100 120 140 160 180 200 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Roasted N:P Uptake N:P Fines N:P N :P 100 120 140 160 180 200  64   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.   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. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 Roasted N:P Uptake N:P Fines N:P N :P 100 120 140 160 180 200 0.00 0.20 0.40 0.60 0.80 1.00 1.20 Roasted N:Mg Uptake N:Mg Fines N:Mg N :M g 100 120 140 160 180 200  65   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.  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 0.00 0.20 0.40 0.60 0.80 1.00 1.20 Roasted N:Mg Uptake N:Mg Fines N:Mg N :M g 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Roasted N:Mg Uptake N:Mg Fines N:Mg N :M g 100 120 140 160 180 200  66  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).   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.  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. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Roasted Mg:P Uptake Mg:P Fines Mg:P M g: P 100 120 140 160 180 200 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Roasted Mg:P Uptake Mg:P Fines Mg:P M g: P 100 120 140 160 180 200  67   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).  0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Roasted Mg:P Uptake Mg:P Fines Mg:P M g: P 100 120 140 160 180 200  68   Figure 48 N:P ratios versus temperature for pH 8.   Figure 49 N:Mg ratios versus temperature for pH 8.  0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 100 120 140 160 180 200 220 N :P  r at io Temperature (°C) Roasted N:P Uptake N:P Fines N:P 0.00 0.20 0.40 0.60 0.80 1.00 1.20 100 120 140 160 180 200 N :M g ra ti o Temperature (°C) Roasted N:Mg Uptake N:Mg Fines N:Mg  69   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 unity at heating temperatures greater than 140°C (Figure 53).   Figure 51 N:P ratios versus temperature for pH 9. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 100 120 140 160 180 200 M g: P  r at io Temperature (°C) Roasted Mg:P Uptake Mg:P Fines Mg:P 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 100 120 140 160 180 200 N :P  r ai o Temperature (°C) Roasted N:P Uptake N:P Fines N:P  70   Figure 52 N:Mg ratios versus temperature for pH 9.   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 0.00 0.20 0.40 0.60 0.80 1.00 1.20 100 120 140 160 180 200 M g: N  r at io Temperature (°C) Roasted Mg:N Uptake Mg:N Fines Mg:N 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 100 120 140 160 180 200 M g: P  r at io Temperature (°C) Roasted Mg:P Uptake Mg:P Fines Mg:P  71  become greater than unity at heating temperatures greater than 140°C but still exhibits an increasing trend (Figure 56).   Figure 54 N:P ratios versus temperature for pH 10.    Figure 55 N:Mg ratios versus temperature for pH 10.  0.00 0.20 0.40 0.60 0.80 1.00 1.20 100 120 140 160 180 200 N :P  r at io Temperatuer (°C) Roasted N:P Uptake N:P Fines N:P 0 0.2 0.4 0.6 0.8 1 1.2 1.4 100 120 140 160 180 200 N :M g ra ti o Temperature (°C) Roasted N:Mg Uptake N:Mg Fines N:Mg  72   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.  0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 100 120 140 160 180 200 M g: P  r at io Temp erature(°C) Roasted Mg:P Uptake Mg:P Fines Mg:P  73   Figure 57 Solid product molar ratios vs. pH for a heating temperature of 100°C.    Figure 58 Solid product molar ratios vs. pH for a heating temperature of 120°C. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 pH 8 pH 9 pH 10 M o la r ra ti o Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 pH 8 pH 9 pH 10 M o la r ra ti o s Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg  74   Figure 59 Solid product molar ratios vs. pH for a heating temperature of 140°C.   Figure 60 Solid product molar ratios vs. pH for a heating temperature of 160°C.   0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 pH 8 pH 9 pH 10 M o la r ra ti o s Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 pH 8 pH 9 pH 10 M o la r ra ti o s Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg  75   Figure 61 Solid product molar ratios vs. pH for a heating temperature of 180°C.   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: Mg 2+ , NH4 + , and PO4 3- . 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 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 pH 8 pH 9 pH 10 M o la r ra ti o s Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 pH 8 pH 9 pH 10 M o la r ra ti o s Roasted N:P Roasted Mg:P Roasted N:Mg Uptake N:P Uptake Mg:P Uptake N:Mg Fines N:P Fines Mg:P Fines N:Mg  76  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.  77  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.  78  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 removal occurred for 40g sorbent heated to 160°C.   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 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  N H 4 + (m g/ L) Time (minutes) 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  79  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 heated to 160°C, in order to maximize ammonium removal.   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 0 20 40 60 80 100 120 140 160 180 200 220 240 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  P O 4 3 - (m g/ L) Time (minutes) 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  80  soluble when heated to 160°C, regardless of sorbent quantity and may, in fact, cause supersaturation with respect to magnesium.    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. 0 20 40 60 80 100 120 140 160 180 200 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  M g2 + (m g/ L) Time (minutes) 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  81  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.   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. 0 100 200 300 400 500 600 700 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  N H 4 + (m g/ L) Time (minutes) 160°C, 20g, 2hr 160°C, 40g, 2hr 160°C, 20g, 2hr, no pH control 160°C, 20g filtrate, 30 min  82    Figure 67 Effect of no pH control on PO4 3- 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.   Figure 68 Effect of no pH control on Mg2+ concentration. 0 100 200 300 400 500 600 700 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  P O 4 3 - (m g/ L) Time (minutes) 160°C, 20g, 2hr 160°C, 40g, 2hr 160°C, 20g, 2hr, no pH control 160°C, 20g filtrate, 30 min 0 100 200 300 400 500 600 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  M g2 + (m g/ L) Time (minutes) 160°C, 20g, 2hr 160°C, 40g, 2hr 160°C, 20g, 2hr, no pH control 160°C, 20g filtrate, 30 min  83  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.   Figure 69 NH4 + concentration vs. time at pH 9.   0 100 200 300 400 500 600 700 800 900 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  N H 4 + (m g/ L) Time (minutes) 80°C, 20g, 2hr 80°C, 40g, 2hr 160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr 105°C, 20g, 2hr 105°C, 40g, 2hr  84  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.   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.  0 2 4 6 8 10 12 14 16 18 20 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  P O 4 3- (m g/ L) Time (minutes) 80°C, 20g, 2hr 80°C, 40g, 2hr 160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr  85   Figure 71 Mg2+ 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 0 5 10 15 20 25 30 35 40 45 50 0 15 30 45 60 75 90 105 120 C o n ce n tr at io n  M g2 + (m g/ L) Time (minutes) 80°C, 20g, 2hr 80°C, 40g, 2hr 160°C, 20g, 24 hr, no pH control 160°C, 40g, 2hr  86  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.   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.  0.00 0.20 0.40 0.60 0.80 1.00 1.20 N :P  r at io roasted uptake fines  87   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 (Figure 74).  Figure 74 Solid product Mg:P ratios for uptake experiments at pH 8.  0.00 0.20 0.40 0.60 0.80 1.00 1.20 N :M g ra ti o roasted uptake fines 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 M g: P  r at io roasted uptake fines  88  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.   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.  0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 80°C, 20g 80°C, 40g 160°C, 20g 160°C, 40g 105°C, 20g 105°C, 40g N :P  r at io roasted uptake fines  89   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.   Figure 77 Solid product Mg:P ratios for uptake experiments at pH 9. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 80°C, 20g 80°C, 40g 160°C, 20g 160°C, 40g 105°C, 20g 105°C, 40g N :M g roasted uptake fines 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 80°C, 20g 80°C, 40g 160°C, 20g 160°C, 40g 105°C, 20g 105°C, 40g M g: P  r at io roasted uptake fines  90  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.    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 0.00 0.20 0.40 0.60 0.80 1.00 1.20 105°C, 10g 160°C, 5.7g 80°C, 20g 160°C, 20g 105°C, 20g M o la r ra ti o s N:P Mg:P N:Mg  91  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 completely dry.   Figure 79 Nitrogen balance for 10g complete dissolution and reformation for a heating temperature of 105°C.   Figure 80 Nitrogen balance for 5.7g complete dissolution and reformation for a heating temperature of 160°C. 0 100 200 300 400 500 600 700 800 Feed Fines Total m g N N sink before after 0 50 100 150 200 250 300 350 400 450 500 Feed Fines Total m g N N sink before after  92   Figure 81 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 80°C.   Figure 82 Nitrogen balance for 20g complete dissolution and reformation for a heating temperature of 160°C.  0 100 200 300 400 500 600 700 800 900 1000 Feed Fines Total m g N N Sink before after 0 100 200 300 400 500 600 700 800 900 1000 Feed Fines Total m g N N sink before after  93   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. 0 200 400 600 800 1000 1200 Feed Fines Total m g N N sink before after  94   Figure 84 2009 specific uptake versus heating temperature for three pH values.   Figure 85 2010 specific uptake versus heating temperature at pH 8. -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 100 120 140 160 180 200 Sp e ci fi c u p ta ke  ( m g N  u p ta ke /g  h e at e d  st ru vi te ) Heating temperature (°C) pH 8 pH 9 pH 10 -4 -3 -2 -1 0 1 2 3 4 5 80 105 160 Sp e ci fi c u p ta ke  ( m g N  p e r g o f h e at e d  st ru vi te ) Heating temperature (°C) Constant pH, 20g no pH control, 20g Constant pH, 40g  95   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. -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 80 105 160 Sp e ci fi c u p ta ke  ( m g N  p e r g o f h e at e d  st ru vi te ) Heating temperature (°C) Constant pH, 20g Constant pH, 40g  96   Figure 87 Raw Gold Bar struvite interior 35x.   Figure 88 Heated Gold Bar struvite interior 70x.   Figure 89 Raw Gold Bar struvite interior 70x.   Figure 90 Raw Gold Bar Struvite cut 500x interior.   Figure 91 Heated Gold Bar struvite 500x interior.   Figure 92 Uptake pH 8.5 cut 500x interior.  97   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,  98  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 $120/day (Britton et al., 2005). The cost summary to treat this volume of wastewater (with Lulu Island WWTP characteristics) is shown in Table 10. The largest cost is for purchasing the raw struvite because it is a very valuable commodity. However, if prices fluctuate and moved downward, this cost might be reduced. The detailed spreadsheet calculations are shown in Appendix E. Table 10 Economic analysis. Price component Cost per day ($/day) Struvite 8670 Caustic 805 Electricity 217 Labour 120 Total 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  99  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.  100  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 re- adsorbed 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.  101   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.   102  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.  103   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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Desalination , 170, 27-32.    107  Appendix A: Instrument operational parameters  Table A. 1 Magnesium AA operating parameters Species Analyzed Magnesium- Mg 2+  Concentration Units mg/L Instrument mode Absorbance Sampling mode Autonormal Calibration mode Concentration Measurement mode Integrate Replicates standard 3 Replicates sample 3 Wavelength 202.6 nm Range 0-100 mg/L Flame type N2O/C2H2 Calibration algorithm New rational Lamp current 4.0 mA  Table A. 2 Lachat parameters for ammonia and phosphate Species Analyzed PO4-P NH3-N      Concentration Units mg/L mg/L  Range 0-100 mg/L 0-100 mg/L      Temperature 63°C 63°C  Method Ammonia 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    108  Appendix B: Mass balance data  Table B. 1 2009 nitrogen balance 100°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc N as NH3 mg/L 112 102 105  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50040 49990  Amount of N in roasted struvite  mg 1400.00 1276.02 1312.24  Amount of N in roasted struvite  g 1.40 1.28 1.31  Feed   Conc N as NH3 mg/L 295 300 321  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 221.25 225 241  Amount of N in feed g 0.22125 0.225 0.24  Total N to start g 1.62 1.50 1.55  Proportion of Mass N in feed  0.1364688 0.149898069 0.155023785  Proportion of N in calcinated pellets  0.8635312 0.850101931 0.844976215  END   Uptake: struvite   Conc N as NH3 mg/L 89.4 72.3 87.8  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 73910 76180 72690  Amount of N in struvite after uptake mg 1651.89 1376.95 1595.55  Amount of N in struvite after uptake g 1.65 1.38 1.60   Fines   Conc N as NH3 mg/L 211 196 216  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 2610 1490 1540  Amount of N in fines mg 137.68 73.01 83.16  Amount of N in fines g 0.14 0.07 0.08   Filter Paper   Conc N as NH3 mg/L 67.6 39.1 94.3  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 3.38 1.96 4.72  Amount of N in filter paper g 0.00 0.00 0.00  Feed     0 mins Conc N as NH3 mg/L 324.2 219 281  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.001621 0.001095 0.001405       15 mins Conc N as NH3 mg/L 187 188 229  109   Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000935 0.00094 0.001145       30 mins Conc N as NH3 mg/L 133 167 218  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000665 0.000835 0.00109       45 mins Conc N as NH3 mg/L 107 158 207  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000535 0.00079 0.001035       60 mins Conc N as NH3 mg/L 84.5 162 196  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0004225 0.00081 0.00098       75 mins Conc N as NH3 mg/L 63.8 158 206  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000319 0.00079 0.00103       90 mins Conc N as NH3 mg/L 45.2 155 202  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000226 0.000775 0.00101       105 mins Conc N as NH3 mg/L 36.6 153 213  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000183 0.000765 0.001065       120 mins Conc N as NH3 mg/L 25.2 156 206  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.017892 0.11076 0.14626   TOTAL N AT END g 1.82 1.57 1.84  Mass N remain in soln (g)  0.02 0.11 0.15  Mass in fines + filter (g)  0.14 0.07 0.09  Mass N in uptake pellets (g)  1.65 1.38 1.60  Mass N lost during sampling (g)  0.00 0.01 0.01  DIFFERENCE g -0.19 -0.07 -0.29  Reduction of mass in solution  0.20 0.11 0.09  RECOVERY (%)  112 105 118    110  Table B. 2 2009 nitrogen balance 120°C  Sample Unit pH 8 pH 9 pH 10   START   Roasted struvite   Conc N as NH3 mg/L 105 90.1 105  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of N in roasted struvite  mg 1312.50 1126.93 1312.24  Amount of N in roasted struvite  g 1.31 1.13 1.31   Feed   Conc N as NH3 mg/L 290 314 327  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 217.5 235.5 245  Amount of N in feed g 0.2175 0.2355 0.25   Total N to start g 1.53 1.36 1.56  Proportion of Mass N in feed  0.142156 9 0.17285345 6 0.15746514 8  Proportion of N in calcinated pellets  0.857843 1 0.82714654 4 0.84253485 2   END   Uptake: struvite   Conc N as NH3 mg/L 84.9 61.5 73.4  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 71070 76670 78760  Amount of N in struvite after uptake mg 1508.46 1178.80 1445.25  Amount of N in struvite after uptake g 1.51 1.18 1.45   Fines   Conc N as NH3 mg/L 217 201 222  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 3670 2010 1850  Amount of N in fines mg 199.10 101.00 102.68  Amount of N in fines g 0.20 0.10 0.10   Filter Paper   Conc N as NH3 mg/L 77.8 50 139  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 3.89 2.50 6.95  Amount of N in filter paper g 0.00 0.00 0.01   Feed     0 mins Conc N as NH3 mg/L 319 168 230  Vol. sample L 0.005 0.005 0.005  111   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 mg/L 170 138 185  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00085 0.00069 0.000925       30 mins Conc N as NH3 mg/L 115 133 166  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000575 0.000665 0.00083       45 mins Conc N as NH3 mg/L 89.5 124 165  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000447 5 0.00062 0.000825       60 mins Conc N as NH3 mg/L 71.8 116 161  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000359 0.00058 0.000805       75 mins Conc N as NH3 mg/L 52.4 117 167  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000262 0.000585 0.000835       90 mins Conc N as NH3 mg/L 36.3 112 160  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000181 5 0.00056 0.0008       105 mins Conc N as NH3 mg/L 25.4 108 159  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000127 0.00054 0.000795       120 mins Conc N as NH3 mg/L 17.4 102 153  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.012354 0.07242 0.10863   TOTAL N AT END g 1.73 1.36 1.67  Mass N remain in soln (g)  0.01 0.07 0.11  Mass in fines + filter (g)  0.20 0.10 0.11  Mass N in uptake pellets (g)  1.51 1.18 1.45  Mass N lost during sampling (g)  0.00 0.01 0.01  DIFFERENCE g -0.20 0.00 -0.11  Reduction of mass in solution  0.20 0.16 0.13  RECOVERY (%)  113 100 107    112  Table B. 3 2009 nitrogen balance 140°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc N as NH3 mg/L 89.9 59.6 86.1  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50000 50010  Amount of N in roasted struvite  mg 1123.75 745.00 1076.47  Amount of N in roasted struvite  g 1.12 0.75 1.08   Feed   Conc N as NH3 mg/L 300 286 316  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 225 214.5 237  Amount of N in feed g 0.225 0.2145 0.24   Total N to start g 1.35 0.96 1.31  Proportion of Mass N in feed  0.166821 1 0.22355393 4 0.18043872 9  Proportion of N in calcinated pellets  0.833178 9 0.77644606 6 0.81956127 1   END   Uptake: struvite   Conc N as NH3 mg/L 74.3 67.3 51.3  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66950 71010 78250  Amount of N in struvite after uptake mg 1243.60 1194.74 1003.56  Amount of N in struvite after uptake g 1.24 1.19 1.00   Fines   Conc N as NH3 mg/L 208 145 248  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 6170 4140 4380  Amount of N in fines mg 320.84 150.08 271.56  Amount of N in fines g 0.32 0.15 0.27   Filter Paper   Conc N as NH3 mg/L 110 81.5 196  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 5.50 4.08 9.80  Amount of N in filter paper g 0.01 0.00 0.01   Feed     0 mins Conc N as NH3 mg/L 329 193 218  Vol. sample L 0.005 0.005 0.005   113   Sample Unit pH 8 pH 9 pH 10  Ammount of N in feed g 0.001645 0.000965 0.00109       15 mins Conc N as NH3 mg/L 164 103 130  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00082 0.000515 0.00065       30 mins Conc N as NH3 mg/L 97.9 79.3 115  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0004895 0.0003965 0.000575       45 mins Conc N as NH3 mg/L 54.8 61.3 104  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000274 0.0003065 0.00052       60 mins Conc N as NH3 mg/L 35 47.2 100  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000175 0.000236 0.0005       75 mins Conc N as NH3 mg/L 26 28.9 98  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00013 0.0001445 0.00049       90 mins Conc N as NH3 mg/L 13.8 15.6 91  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000069 0.000078 0.000455       105 mins Conc N as NH3 mg/L 10 5.6 90.4  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00005 0.000028 0.000452       120 mins Conc N as NH3 mg/L 8.38 2.37 86.2  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.0059498 0.0016827 0.061202  TOTAL N AT END g 1.58 1.35 1.35  Mass N remain in soln (g)  0.01 0.00 0.06  Mass in fines + filter (g)  0.33 0.15 0.28  Mass N in uptake pellets (g)  1.24 1.19 1.00  Mass N lost during sampling (g)  0.00 0.00 0.00  DIFFERENCE g -0.23 -0.39 -0.04  Reduction of mass in solution  0.22 0.21 0.17  RECOVERY (%)  117 141 103    114  Table B. 4 2009 nitrogen balance 160°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc N as NH3 mg/L 69.8 58.4 75.1  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of N in roasted struvite  mg 872.50 730.44 938.56  Amount of N in roasted struvite  g 0.87 0.73 0.94  Feed   Conc N as NH3 mg/L 301 298 326  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 225.75 223.5 245  Amount of N in feed g 0.22575 0.2235 0.24   Total N to start g 1.10 0.95 1.18  Proportion of Mass N in feed  0.205554 3 0.23429195 6 0.20666706 3  Proportion of N in calcinated pellets  0.794445 7 0.76570804 4 0.79333293 7   END   Uptake: struvite   Conc N as NH3 mg/L 60.4 49.1 51  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66280 72370 73050  Amount of N in struvite after uptake mg 1000.83 888.34 931.39  Amount of N in struvite after uptake g 1.00 0.89 0.93   Fines   Conc N as NH3 mg/L 168 207 188  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 5830 3140 3250  Amount of N in fines mg 244.86 162.50 152.75  Amount of N in fines g 0.24 0.16 0.15   Filter Paper   Conc N as NH3 mg/L 187 63.5 249  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 9.35 3.18 12.45  Amount of N in filter paper g 0.01 0.00 0.01   Feed     0 mins Conc N as NH3 mg/L 325 216 261  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.001625 0.00108 0.001305   115   Sample Unit pH 8 pH 9 pH 10 15 mins Conc N as NH3 mg/L 137 124 130  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000685 0.00062 0.00065       30 mins Conc N as NH3 mg/L 47.5 94 115  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000237 5 0.00047 0.000575       45 mins Conc N as NH3 mg/L 20.2 67.6 128  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000101 0.000338 0.00064       60 mins Conc N as NH3 mg/L 12.5 51.2 113  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000062 5 0.000256 0.000565       75 mins Conc N as NH3 mg/L 8.93 39.7 95.9  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 4.465E-05 0.0001985 0.0004795       90 mins Conc N as NH3 mg/L 6.22 32.2 99  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000031 1 0.000161 0.000495       105 mins Conc N as NH3 mg/L 6.41 23.3 94.2  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 3.205E-05 0.0001165 0.000471       120 mins Conc N as NH3 mg/L 6.24 7.27 88.8  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.004430 4 0.0051617 0.063048   TOTAL N AT END g 1.26 1.06 1.16  Mass N remain in soln (g)  0.00 0.01 0.06  Mass in fines + filter (g)  0.25 0.17 0.17  Mass N in uptake pellets (g)  1.00 0.89 0.93  Mass N lost during sampling (g)  0.00 0.00 0.01  DIFFERENCE g -0.16 -0.11 0.02  Reduction of mass in solution  0.22 0.22 0.18  RECOVERY (%)  115 111 98    116  Table B. 5 2009 nitrogen balance 180°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc N as NH3 mg/L 56.2 53.6 83.7  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 49990 50010  Amount of N in roasted struvite  mg 702.50 669.87 1046.46  Amount of N in roasted struvite  g 0.70 0.67 1.05  Feed   Conc N as NH3 mg/L 293 290 332  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 219.75 217.5 249  Amount of N in feed g 0.21975 0.2175 0.25   Total N to start g 0.9223 0.8874 1.2955  Proportion of Mass N in feed  0.238276 0.24510743 0.192209828  Proportion of N in calcinated pellets  0.761724 0.75489257 0.807790172  END   Uptake: struvite   Conc N as NH3 mg/L 45.2 55.7 51.3  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 56710 66720 63760  Amount of N in struvite after uptake mg 640.82 929.08 817.72  Amount of N in struvite after uptake g 0.64 0.93 0.82   Fines   Conc N as NH3 mg/L 155 224 160  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 8740 4100 4930  Amount of N in fines mg 338.68 229.60 197.20  Amount of N in fines g 0.34 0.23 0.20   Filter Paper   Conc N as NH3 mg/L 130 81.5 169  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 6.50 4.08 8.45  Amount of N in filter paper g 0.01 0.00 0.01   Feed     0 mins Conc N as NH3 mg/L 323 216 294  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.001615 0.00108 0.00147       15 mins Conc N as NH3 mg/L 170 113 224   117    Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00085 0.000565 0.00112       30 mins Conc N as NH3 mg/L 56.2 66.1 198  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000281 0.0003305 0.00099       45 mins Conc N as NH3 mg/L 15.9 50.7 182  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0000795 0.0002535 0.00091       60 mins Conc N as NH3 mg/L 5.43 32.4 163  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 2.715E-05 0.000162 0.000815       75 mins Conc N as NH3 mg/L 5.36 16.9 174  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0000268 0.0000845 0.00087       90 mins Conc N as NH3 mg/L 3.7 8.6 164  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0000185 0.000043 0.00082       105 mins Conc N as NH3 mg/L 5.3 4.21 153  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0000265 0.00002105 0.000765       120 mins Conc N as NH3 mg/L 6.48 4.54 159  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.0046008 0.0032234 0.11289   TOTAL N AT END g 0.99 1.17 1.14  Mass N remain in soln (g)  0.00 0.00 0.11  Mass in fines + filter (g)  0.35 0.23 0.21  Mass N in uptake pellets (g)  0.64 0.93 0.82  Mass N lost during sampling (g)  0.00 0.00 0.01  DIFFERENCE g -0.07 -0.28 0.15  Reduction of mass in solution  0.21 0.21 0.13  RECOVERY (%)  108 132 88    118  Table B. 6 2009 nitrogen balance 200°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc N as NH3 mg/L 45.4 46.6 49.9  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50010 50020  Amount of N in roasted struvite  mg 567.50 582.62 624.00  Amount of N in roasted struvite  g 0.57 0.58 0.62  Feed   Conc N as NH3 mg/L 298 321 317  Vol. sample L 0.75 0.75 0.75  Amount of N in feed mg 223.5 240.75 238  Amount of N in feed g 0.2235 0.24075 0.24   Total N to start g 0.79 0.82 0.86  Proportion of Mass N in feed  0.2825537 0.292397128 0.27589224  Proportion of N in calcinated pellets  0.7174463 0.707602872 0.72410776   END   Uptake: struvite   Conc N as NH3 mg/L 37.5 34.7 37.4  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 55400 68170 67560  Amount of N in struvite after uptake mg 519.38 591.37 631.69  Amount of N in struvite after uptake g 0.52 0.59 0.63   Fines   Conc N as NH3 mg/L 172 202 193  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 7000 2640 2030  Amount of N in fines mg 301.00 133.32 97.95  Amount of N in fines g 0.30 0.13 0.10   Filter Paper   Conc N as NH3 mg/L 167 54.7 61.1  Vol. sample L 0.05 0.05 0.05  Amount of N on filter paper mg 8.35 2.74 3.06  Amount of N in filter paper g 0.01 0.00 0.00   Feed     0 mins Conc N as NH3 mg/L 325 298 259  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.001625 0.00149 0.001295   119   Sample Unit pH 8 pH 9 pH 10 15 mins Conc N as NH3 mg/L 226 143 231  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00113 0.000715 0.001155       30 mins Conc N as NH3 mg/L 152 111 197  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.00076 0.000555 0.000985       45 mins Conc N as NH3 mg/L 58.5 103 181  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0002925 0.000515 0.000905       60 mins Conc N as NH3 mg/L 40.3 81.4 184  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.0002015 0.000407 0.00092       75 mins Conc N as NH3 mg/L 14.4 72.1 163  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 0.000072 0.0003605 0.000815       90 mins Conc N as NH3 mg/L 6.81 55.2 166  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 3.405E-05 0.000276 0.00083       105 mins Conc N as NH3 mg/L 6.11 56.8 169  Vol. sample L 0.005 0.005 0.005  Ammount of N in feed g 3.055E-05 0.000284 0.000845       120 mins Conc N as NH3 mg/L 5.06 55.4 164  Vol. sample L 0.71 0.71 0.71  Ammount of N in feed g 0.0035926 0.039334 0.11644   TOTAL N AT END g 0.84 0.77 0.86  Mass N remain in soln (g)  0.00 0.04 0.12  Mass in fines + filter (g)  0.31 0.14 0.10  Mass N in uptake pellets (g)  0.52 0.59 0.63  Mass N lost during sampling (g)  0.00 0.00 0.01  DIFFERENCE g -0.05 0.05 0.00  Reduction of mass in solution  0.22 0.20 0.11  RECOVERY (%)  106 94 99    120  Table B. 7 2009 phosphorus balance 100°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 846 930 839  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50040 49990  Amount of P in roasted struvite  mg 10575.00 11634.30 10485.40  Amount of P in roasted struvite  g 10.58 11.63 10.49   Feed   Conc P as PO4 mg/L 21.5 10.4 36.3  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 16.125 7.8 27  Amount of P in feed g 0.016125 0.0078 0.03   Total P to start g 10.59 11.64 10.51  Proportion of Mass P in feed  0.001522 5 0.00066998 2 0.00258974 3  Proportion of P in calcinated pellets  0.998477 5 0.99933001 8 0.99741025 7   END   Uptake: struvite   Conc P as PO4 mg/L 586 527 607  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 73910 76180 72690  Amount of P in struvite after uptake mg 10827.82 10036.72 11030.71  Amount of P in struvite after uptake g 10.83 10.04 11.03   Fines   Conc P as PO4 mg/L 561 538 570  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 2610 1490 1540  Amount of P in fines mg 366.05 200.41 219.45  Amount of P in fines g 0.37 0.20 0.22   Filter Paper   Conc P as PO4 mg/L 156 95.8 84.5  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 7.80 4.79 4.23  Amount of P in filter paper g 0.01 0.00 0.00   Feed     0 mins Conc P as PO4 mg/L 80.7 69.9 96.4  Vol. sample L 0.005 0.005 0.005   121   Sample Unit pH 8 pH 9 pH 10  Ammount of P in feed g 0.0004035 0.0003495 0.000482       15 mins Conc P as PO4 mg/L 107 81.3 107  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000535 0.0004065 0.000535       30 mins Conc P as PO4 mg/L 130 83.7 108  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00065 0.0004185 0.00054       45 mins Conc P as PO4 mg/L 154 84.3 114  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00077 0.0004215 0.00057       60 mins Conc P as PO4 mg/L 177 89 110  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000885 0.000445 0.00055       75 mins Conc P as PO4 mg/L 203 90.8 100  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001015 0.000454 0.0005       90 mins Conc P as PO4 mg/L 225 93 110  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001125 0.000465 0.00055       105 mins Conc P as PO4 mg/L 260 97.4 111  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.0013 0.000487 0.000555       120 mins Conc P as PO4 mg/L 251 98.6 105  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.17821 0.070006 0.07455  TOTAL P AT END g 11.39 10.32 11.33  Mass P remain in soln (g)  0.18 0.07 0.07  Mass in fines + filter (g)  0.37 0.21 0.22  Mass P in uptake pellets (g)  10.83 10.04 11.03  Mass P lost during sampling (g)  0.01 0.00 0.00  DIFFERENCE g -0.80 1.33 -0.82  Reduction of mass in solution  -0.17 -0.07 -0.05  RECOVERY (%)  108 89 108   122  Table B. 8 2009 phosphorus balance 120°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 908 763 796  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of P in roasted struvite  mg 11350.00 9543.22 9948.01  Amount of P in roasted struvite  g 11.35 9.54 9.95   Feed   Conc P as PO4 mg/L 15.6 9.09 10.9  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 11.7 6.8175 8  Amount of P in feed g 0.0117 0.0068175 0.01   Total P to start g 11.36 9.55 9.96  Proportion of Mass P in feed  0.001029 8 0.00071387 1 0.00082109 8  Proportion of P in calcinated pellets  0.998970 2 0.99928612 9 0.99917890 2   END   Uptake: struvite   Conc P as PO4 mg/L 565 443 572  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 71070 76670 78760  Amount of P in struvite after uptake mg 10038.64 8491.20 11262.68  Amount of P in struvite after uptake g 10.04 8.49 11.26   Fines   Conc P as PO4 mg/L 533 506 552  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 3670 2010 1850  Amount of P in fines mg 489.03 254.27 255.30  Amount of P in fines g 0.49 0.25 0.26   Filter Paper   Conc P as PO4 mg/L 169 123 136  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 8.45 6.15 6.80  Amount of P in filter paper g 0.01 0.01 0.01   Feed     0 mins Conc P as PO4 mg/L 10.7 115 72.2  Vol. sample L 0.005 0.005 0.005   123   Sample Unit pH 8 pH 9 pH 10  Ammount of P in feed g 0.0000535 0.000575 0.000361       15 mins Conc P as PO4 mg/L 104 132 84  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00052 0.00066 0.00042       30 mins Conc P as PO4 mg/L 132 134 87.1  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00066 0.00067 0.0004355       45 mins Conc P as PO4 mg/L 151 137 83.8  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000755 0.000685 0.000419       60 mins Conc P as PO4 mg/L 181 138 84.9  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000905 0.00069 0.0004245       75 mins Conc P as PO4 mg/L 200 141 91  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001 0.000705 0.000455       90 mins Conc P as PO4 mg/L 235 143 88.8  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001175 0.000715 0.000444       105 mins Conc P as PO4 mg/L 264 149 94.8  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00132 0.000745 0.000474       120 mins Conc P as PO4 mg/L 281 151 98  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.19951 0.10721 0.06958  TOTAL P AT END g 10.74 8.86 11.60  Mass P remain in soln (g)  0.20 0.11 0.07  Mass in fines + filter (g)  0.50 0.26 0.26  Mass P in uptake pellets (g)  10.04 8.49 11.26  Mass P lost during sampling (g)  0.01 0.01 0.00  DIFFERENCE g 0.62 0.69 -1.64  Reduction of mass in solution  -0.19 -0.11 -0.06  RECOVERY (%)  95 93 116   124  Table B. 9 2009 phosphorus balance 140°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 739 608 834  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50000 50010  Amount of P in roasted struvite  mg 9237.50 7600.00 10427.09  Amount of P in roasted struvite  g 9.24 7.60 10.43   Feed   Conc P as PO4 mg/L 20.1 11.2 13.9  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 15.075 8.4 10  Amount of P in feed g 0.015075 0.0084 0.01   Total P to start g 9.25 7.61 10.44  Proportion of Mass P in feed  0.001629 3 0.00110404 3 0.00099880 1  Proportion of P in calcinated pellets  0.998370 7 0.99889595 7 0.99900119 9   END   Uptake: struvite   Conc P as PO4 mg/L 590 526 517  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66950 71010 78250  Amount of P in struvite after uptake mg 9875.13 9337.82 10113.81  Amount of P in struvite after uptake g 9.88 9.34 10.11   Fines   Conc P as PO4 mg/L 533 445 531  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 6170 4140 4380  Amount of P in fines mg 822.15 460.58 581.45  Amount of P in fines g 0.82 0.46 0.58   Filter Paper   Conc P as PO4 mg/L 258 191 193  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 12.90 9.55 9.65  Amount of P in filter paper g 0.01 0.01 0.01   Feed     0 mins Conc P as PO4 mg/L 12.4 101 123  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000062 0.000505 0.000615  125    Sample Unit pH 8 pH 9 pH 10 15 mins Conc P as PO4 mg/L 157 115 132  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000785 0.000575 0.00066       30 mins Conc P as PO4 mg/L 244 113 133  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00122 0.000565 0.000665       45 mins Conc P as PO4 mg/L 238 119 137  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00119 0.000595 0.000685       60 mins Conc P as PO4 mg/L 251 128 123  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001255 0.00064 0.000615       75 mins Conc P as PO4 mg/L 279 135 125  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001395 0.000675 0.000625       90 mins Conc P as PO4 mg/L 297 150 127  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001485 0.00075 0.000635       105 mins Conc P as PO4 mg/L 377 174 144  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001885 0.00087 0.00072       120 mins Conc P as PO4 mg/L 392 229 141  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.27832 0.16259 0.10011   TOTAL P AT END g 11.00 9.98 10.81  Mass P remain in soln (g)  0.28 0.16 0.10  Mass in fines + filter (g)  0.84 0.47 0.59  Mass P in uptake pellets (g)  9.88 9.34 10.11  Mass P lost during sampling (g)  0.01 0.01 0.01  DIFFERENCE g -1.75 -2.37 -0.37  Reduction of mass in solution  -0.27 -0.16 -0.09  RECOVERY (%)  119 131 104    126  Table B. 10 2009 phosphorus balance 160°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 680 577 724  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of P in roasted struvite  mg 8500.00 7216.83 9048.19  Amount of P in roasted struvite  g 8.50 7.22 9.05   Feed   Conc P as PO4 mg/L 27.7 11.8 13.7  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 20.775 8.85 10  Amount of P in feed g 0.020775 0.00885 0.01   Total P to start g 8.52 7.23 9.06  Proportion of Mass P in feed  0.002438 2 0.00122479 9 0.00113429 8  Proportion of P in calcinated pellets  0.997561 8 0.99877520 1 0.99886570 2   END   Uptake: struvite   Conc P as PO4 mg/L 535 448 484  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66280 72370 73050  Amount of P in struvite after uptake mg 8864.95 8105.44 8839.05  Amount of P in struvite after uptake g 8.86 8.11 8.84   Fines   Conc P as PO4 mg/L 488 508 485  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 5830 3140 3250  Amount of P in fines mg 711.26 398.78 394.06  Amount of P in fines g 0.71 0.40 0.39   Filter Paper   Conc P as PO4 mg/L 485 170 556  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 24.25 8.50 27.80  Amount of P in filter paper g 0.02 0.01 0.03   Feed     0 mins Conc P as PO4 mg/L 19.8 104 100  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000099 0.00052 0.0005  127    Sample Unit pH 8 pH 9 pH 10 15 mins Conc P as PO4 mg/L 200 128 128  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001 0.00064 0.00064       30 mins Conc P as PO4 mg/L 246 128 126  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00123 0.00064 0.00063       45 mins Conc P as PO4 mg/L 282 126 120  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00141 0.00063 0.0006       60 mins Conc P as PO4 mg/L 339 136 116  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001695 0.00068 0.00058       75 mins Conc P as PO4 mg/L 371 139 112  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001855 0.000695 0.00056       90 mins Conc P as PO4 mg/L 383 145 107  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001915 0.000725 0.000535       105 mins Conc P as PO4 mg/L 410 164 109  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00205 0.00082 0.000545       120 mins Conc P as PO4 mg/L 412 197 103  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.29252 0.13987 0.07313   TOTAL P AT END g 9.90 8.66 9.34  Mass P remain in soln (g)  0.29 0.14 0.07  Mass in fines + filter (g)  0.74 0.41 0.42  Mass P in uptake pellets (g)  8.86 8.11 8.84  Mass P lost during sampling (g)  0.01 0.01 0.00  DIFFERENCE g -1.38 -1.43 -0.28  Reduction of mass in solution  -0.28 -0.14 -0.07  RECOVERY (%)  116 120 103    128  Table B. 11 2009 phosphorus balance 180°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 577 561 687  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 49990 50010  Amount of P in roasted struvite  mg 7212.50 7011.10 8589.22  Amount of P in roasted struvite  g 7.21 7.01 8.59   Feed   Conc P as PO4 mg/L 22.5 14.4 12  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 16.875 10.8 9  Amount of P in feed g 0.016875 0.0108 0.01   Total P to start g 7.2294 7.0219 8.5982  Proportion of Mass P in feed  0.002334 2 0.00153804 6 0.00104672 9  Proportion of P in calcinated pellets  0.997665 8 0.99846195 4 0.99895327 1   END   Uptake: struvite   Conc P as PO4 mg/L 435 466 462  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 56710 66720 63760  Amount of P in struvite after uptake mg 6167.21 7772.88 7364.28  Amount of P in struvite after uptake g 6.17 7.77 7.36   Fines   Conc P as PO4 mg/L 462 558 478  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 8740 4100 4930  Amount of P in fines mg 1009.47 571.95 589.14  Amount of P in fines g 1.01 0.57 0.59   Filter Paper   Conc P as PO4 mg/L 325 167 172  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 16.25 8.35 8.60  Amount of P in filter paper g 0.02 0.01 0.01   Feed     0 mins Conc P as PO4 mg/L 13.2 90.7 51  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000066 0.0004535 0.000255  129    Sample Unit pH 8 pH 9 pH 10 15 mins Conc P as PO4 mg/L 208 138 43.2  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00104 0.00069 0.000216       30 mins Conc P as PO4 mg/L 261 151 38.5  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001305 0.000755 0.0001925       45 mins Conc P as PO4 mg/L 366 155 32.9  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00183 0.000775 0.0001645       60 mins Conc P as PO4 mg/L 390 164 30.5  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00195 0.00082 0.0001525       75 mins Conc P as PO4 mg/L 443 169 27.5  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.002215 0.000845 0.0001375       90 mins Conc P as PO4 mg/L 466 207 25.9  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00233 0.001035 0.0001295       105 mins Conc P as PO4 mg/L 442 219 24.4  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00221 0.001095 0.000122       120 mins Conc P as PO4 mg/L 432 254 21.1  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.30672 0.18034 0.014981   TOTAL P AT END g 7.51 8.54 7.98  Mass P remain in soln (g)  0.31 0.18 0.01  Mass in fines + filter (g)  1.03 0.58 0.60  Mass P in uptake pellets (g)  6.17 7.77 7.36  Mass P lost during sampling (g)  0.01 0.01 0.00  DIFFERENCE g -0.28 -1.52 0.62  Reduction of mass in solution  -0.30 -0.18 -0.01  RECOVERY (%)  104 122 93    130  Table B. 12 2009 phosphorus balance 200°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc P as PO4 mg/L 511 559 564  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50010 50020  Amount of P in roasted struvite  mg 6387.50 6988.90 7052.82  Amount of P in roasted struvite  g 6.39 6.99 7.05   Feed   Conc P as PO4 mg/L 24 12 11.6  Vol. sample L 0.75 0.75 0.75  Amount of P in feed mg 18 9 9  Amount of P in feed g 0.018 0.009 0.01   Total P to start g 6.41 7.00 7.06  Proportion of Mass P in feed  0.002810 1 0.00128610 1 0.00123202 9  Proportion of P in calcinated pellets  0.997189 9 0.99871389 9 0.99876797 1   END   Uptake: struvite   Conc P as PO4 mg/L 366 391 373  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 55400 68170 67560  Amount of P in struvite after uptake mg 5069.10 6663.62 6299.97  Amount of P in struvite after uptake g 5.07 6.66 6.30   Fines   Conc P as PO4 mg/L 460 493 469  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 7000 2640 2030  Amount of P in fines mg 805.00 325.38 238.02  Amount of P in fines g 0.81 0.33 0.24   Filter Paper   Conc P as PO4 mg/L 390 118 130  Vol. sample L 0.05 0.05 0.05  Amount of P on filter paper mg 19.50 5.90 6.50  Amount of P in filter paper g 0.02 0.01 0.01   Feed     0 mins Conc P as PO4 mg/L 14.3 134 39  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000071 0.00067 0.000195  131    Sample Unit pH 8 pH 9 pH 10 15 mins Conc P as PO4 mg/L 183 82.5 51.3  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000915 0.0004125 0.0002565       30 mins Conc P as PO4 mg/L 193 95.5 16.6  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.000965 0.0004775 0.000083       45 mins Conc P as PO4 mg/L 227 96.1 13  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.001135 0.0004805 0.000065       60 mins Conc P as PO4 mg/L 268 95.2 10.9  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00134 0.000476 0.0000545       75 mins Conc P as PO4 mg/L 288 97.1 10.9  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00144 0.0004855 0.0000545       90 mins Conc P as PO4 mg/L 354 95.1 10.4  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00177 0.0004755 0.000052       105 mins Conc P as PO4 mg/L 374 93.1 9.35  Vol. sample L 0.005 0.005 0.005  Ammount of P in feed g 0.00187 0.0004655 0.00004675       120 mins Conc P as PO4 mg/L 369 93.6 9.44  Vol. sample L 0.71 0.71 0.71  Ammount of P in feed g 0.26199 0.066456 0.0067024   TOTAL P AT END g 6.17 7.07 6.55  Mass P remain in soln (g)  0.26 0.07 0.01  Mass in fines + filter (g)  0.82 0.33 0.24  Mass P in uptake pellets (g)  5.07 6.66 6.30  Mass P lost during sampling (g)  0.01 0.00 0.00  DIFFERENCE g 0.24 -0.07 0.51  Reduction of mass in solution  -0.25 -0.06 0.00  RECOVERY (%)  96 101 93   132  Table B. 13 2009 magnesium balance 100°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 558.125 534.595 445.265  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50040 49990  Amount of Mg in roasted struvite  mg 6976.56 6687.78 5564.70  Amount of Mg in roasted struvite  g 6.98 6.69 5.56  Feed   Conc Mg mg/L 2.5635 28.323 30.62  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 1.922625 21.24225 23  Amount of Mg in feed g 0.001922 6 0.02124225 0.02   Total Mg to start g 6.98 6.71 5.59  Proportion of Mass Mg in feed  0.000275 5 0.00316622 0.00410994 6  Proportion of Mg in calcinated pellets  0.999724 5 0.99683378 0.99589005 4   END   Uptake: struvite   Conc Mg mg/L 377.82 338.585 336.215  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 73910 76180 72690  Amount of Mg in struvite after uptake mg 6981.17 6448.35 6109.87  Amount of Mg in struvite after uptake g 6.98 6.45 6.11   Fines   Conc Mg mg/L 355.68 400.205 409.135  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 2610 1490 1540  Amount of Mg in fines mg 232.08 149.08 157.52  Amount of Mg in fines g 0.23 0.15 0.16   Filter Paper   Conc Mg mg/L 97.555 54.902 62.6125  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 4.88 2.75 3.13  Amount of Mg in filter paper g 0.00 0.00 0.00   Feed     0 mins Conc Mg mg/L 10.334 5.369 2.3755  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 5.167E-05 0.00002684 5 1.18775E-05  133    Sample Unit pH 8 pH 9 pH 10 15 mins Conc Mg mg/L 7.1505 2.0095 2.13  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 3.575E-05 1.00475E-05 0.00001065       30 mins Conc Mg mg/L 4.4105 2.1565 1.706  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 2.205E-05 1.07825E-05 0.00000853       45 mins Conc Mg mg/L 3.025 1.8325 1.6275  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 1.513E-05 9.1625E-06 8.1375E-06       60 mins Conc Mg mg/L 5.5465 2.59 1.7675  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 2.773E-05 0.00001295 8.8375E-06       75 mins Conc Mg mg/L 1.729 2.4095 1.9055  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 8.645E-06 1.20475E-05 9.5275E-06       90 mins Conc Mg mg/L 26.411 1.928 2.031  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.000132 1 0.00000964 0.00001015 5       105 mins Conc Mg mg/L 14.8145 1.8995 1.3155  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 7.407E-05 9.4975E-06 6.5775E-06       120 mins Conc Mg mg/L 6.116 1.9635 1.883  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.004342 4 0.00139408 5 0.00133693   TOTAL Mg AT END g 7.22 6.60 6.27  Mass Mg remain in soln (g)  0.00 0.00 0.00  Mass in fines + filter (g)  0.24 0.15 0.16  Mass Mg in uptake pellets (g)  6.98 6.45 6.11  Mass Mg lost during sampling (g)  0.00 0.00 0.00  DIFFERENCE g -0.24 0.11 -0.68  Reduction of mass in solution  0.00 0.02 0.02  RECOVERY (%)  104 98 112    134  Table B. 14 2009 magnesium balance 120°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 528.945 550.155 600.42  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of Mg in roasted struvite  mg 6611.81 6881.06 7503.75  Amount of Mg in roasted struvite  g 6.61 6.88 7.50  Feed   Conc Mg mg/L 3.4015 26.1955 35.143  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 2.551125 19.646625 26  Amount of Mg in feed g 0.0025511 0.019646625 0.03  Total Mg to start g 6.61 6.90 7.53  Proportion of Mass Mg in feed  0.0003857 0.002847044 0.003500249  Proportion of Mg in calcinated pellets  0.9996143 0.997152956 0.996499751  END   Uptake: struvite   Conc Mg mg/L 426.26 356.305 330.615  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 71070 76670 78760  Amount of Mg in struvite after uptake mg 7573.57 6829.48 6509.81  Amount of Mg in struvite after uptake g 7.57 6.83 6.51   Fines   Conc Mg mg/L 331.725 392.72 387.22  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 3670 2010 1850  Amount of Mg in fines mg 304.36 197.34 179.09  Amount of Mg in fines g 0.30 0.20 0.18   Filter Paper   Conc Mg mg/L 35.575 79.6695 227.495  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 1.78 3.98 11.37  Amount of Mg in filter paper g 0.00 0.00 0.01   Feed     0 mins Conc Mg mg/L 3.6065 5.661 3.9515  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 1.803E-05 0.000028305 1.97575E-05       15 mins Conc Mg mg/L 3.224 7.218 2.346  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 1.612E-05 0.00003609 0.00001173   135   Sample Unit pH 8 pH 9 pH 10 30 mins Conc Mg mg/L 1.2475 5.146 2.793  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 6.238E-06 0.00002573 0.000013965       45 mins Conc Mg mg/L 2.173 3.831 3.2175  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 1.087E-05 0.000019155 1.60875E-05       60 mins Conc Mg mg/L 2.173 4.188 3.226  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 1.087E-05 0.00002094 0.00001613       75 mins Conc Mg mg/L 7.9105 4.175 3.2005  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 3.955E-05 0.000020875 1.60025E-05       90 mins Conc Mg mg/L 14.056 4.0325 3.1655  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 7.028E-05 2.01625E-05 1.58275E-05       105 mins Conc Mg mg/L 25.746 4.9435 1.8175  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0001287 2.47175E-05 9.0875E-06       120 mins Conc Mg mg/L 5.7625 4.432 4.0565  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.0040914 0.00314672 0.002880115  TOTAL Mg AT END g 7.88 7.03 6.70  Mass Mg remain in soln (g)  0.00 0.00 0.00  Mass in fines + filter (g)  0.31 0.20 0.19  Mass Mg in uptake pellets (g)  7.57 6.83 6.51  Mass Mg lost during sampling (g)  0.00 0.00 0.00  DIFFERENCE g -1.27 -0.13 0.83  Reduction of mass in solution  0.00 0.02 0.02  RECOVERY (%)  119 102 89    136  Table B. 15 2009 magnesium balance 140°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 507.745 460.25 526.545  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50000 50010  Amount of Mg in roasted struvite  mg 6346.81 5753.13 6583.13  Amount of Mg in roasted struvite  g 6.35 5.75 6.58  Feed   Conc Mg mg/L 6.7985 28.5885 27.5075  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 5.098875 21.441375 21  Amount of Mg in feed g 0.0050989 0.021441375 0.02  Total Mg to start g 6.35 5.77 6.60  Proportion of Mass Mg in feed  0.0008027 0.003713071 0.003124073  Proportion of Mg in calcinated pellets  0.9991973 0.996286929 0.996875927  END   Uptake: struvite   Conc Mg mg/L 414.535 403.015 287.29  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66950 71010 78250  Amount of Mg in struvite after uptake mg 6938.28 7154.52 5620.11  Amount of Mg in struvite after uptake g 6.94 7.15 5.62  Fines   Conc Mg mg/L 330.7 344.835 429.195  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 6170 4140 4380  Amount of Mg in fines mg 510.10 356.90 469.97  Amount of Mg in fines g 0.51 0.36 0.47   Filter Paper   Conc Mg mg/L 206.065 134.86 327.19  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 10.30 6.74 16.36  Amount of Mg in filter paper g 0.01 0.01 0.02   Feed     0 mins Conc Mg mg/L 38.706 11.859 4.6275  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0001935 0.000059295 2.31375E-05       15 mins Conc Mg mg/L 66.6185 13.1475 8.257  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003331 6.57375E-05 0.000041285       30 mins Conc Mg mg/L 51.0805 13.3695 10.588  137   Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0002554 6.68475E-05 0.00005294       45 mins Conc Mg mg/L 55.735 15.3885 11.463  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0002787 7.69425E-05 0.000057315       60 mins Conc Mg mg/L 68.7255 16.968 12.4735  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003436 0.00008484 6.23675E-05       75 mins Conc Mg mg/L 82.277 19.1225 12.971  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0004114 9.56125E-05 0.000064855       90 mins Conc Mg mg/L 74.7505 24.509 13.2465  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003738 0.000122545 6.62325E-05       105 mins Conc Mg mg/L 150.435 40.1565 12.5235  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0007522 0.000200783 6.26175E-05       120 mins Conc Mg mg/L 166.485 51.987 13.664  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.1182044 0.03691077 0.00970144   TOTAL Mg AT END g 7.58 7.56 6.12  Mass Mg remain in soln (g)  0.12 0.04 0.01  Mass in fines + filter (g)  0.52 0.36 0.49  Mass Mg in uptake pellets (g)  6.94 7.15 5.62  Mass Mg lost during sampling (g)  0.00 0.00 0.00  DIFFERENCE g -1.23 -1.78 0.49  Reduction of mass in solution  -0.12 -0.02 0.01  RECOVERY (%)  119 131 93    138  Table B. 16 2009 magnesium balance 160°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 590.755 461.765 971.415  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50030 49990  Amount of Mg in roasted struvite  mg 7384.44 5775.53 12140.26  Amount of Mg in roasted struvite  g 7.38 5.78 12.14  Feed   Conc Mg mg/L 35.0835 32.135 32.4115  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 26.312625 24.10125 24  Amount of Mg in feed g 0.0263126 0.02410125 0.02  Total Mg to start g 7.41 5.80 12.16  Proportion of Mass Mg in feed  0.0035506 0.004155655 0.001998314  Proportion of Mg in calcinated pellets  0.9964494 0.995844345 0.998001686  END   Uptake: struvite   Conc Mg mg/L 436.385 377.77 389.55  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 66280 72370 73050  Amount of Mg in struvite after uptake mg 7230.90 6834.80 7114.16  Amount of Mg in struvite after uptake g 7.23 6.83 7.11  Fines   Conc Mg mg/L 348.38 369.735 313.235  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 5830 3140 3250  Amount of Mg in fines mg 507.76 290.24 254.50  Amount of Mg in fines g 0.51 0.29 0.25   Filter Paper   Conc Mg mg/L 348.28 115.81 357.06  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 17.41 5.79 17.85  Amount of Mg in filter paper g 0.02 0.01 0.02   Feed     0 mins Conc Mg mg/L 34.1185 13.064 6.4235  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0001706 0.00006532 3.21175E-05       15 mins Conc Mg mg/L 55.4185 14.612 11.5665  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0002771 0.00007306 5.78325E-05       30 mins Conc Mg mg/L 73.5385 15.296 20.2225  139   Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003677 0.00007648 0.000101113       45 mins Conc Mg mg/L 73.3185 16.84 24.2205  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003666 0.0000842 0.000121103       60 mins Conc Mg mg/L 78.32 20.5585 24.8635  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0003916 0.000102793 0.000124318       75 mins Conc Mg mg/L 83.1175 19.958 24.075  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0004156 0.00009979 0.000120375       90 mins Conc Mg mg/L 90.683 21.6575 26.605  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0004534 0.000108288 0.000133025       105 mins Conc Mg mg/L 170.595 27.622 30.0545  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.000853 0.00013811 0.000150273       120 mins Conc Mg mg/L 162.905 25.5055 33.3745  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.1156626 0.018108905 0.023695895   TOTAL Mg AT END g 7.88 7.15 7.41  Mass Mg remain in soln (g)  0.12 0.02 0.02  Mass in fines + filter (g)  0.53 0.30 0.27  Mass Mg in uptake pellets (g)  7.23 6.83 7.11  Mass Mg lost during sampling (g)  0.00 0.00 0.00  DIFFERENCE g -0.46 -1.35 4.75  Reduction of mass in solution  -0.09 0.01 0.00  RECOVERY (%)  106 123 61     140  Table B. 17 2009 magnesium balance 180°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 520.095 546.14 607.225  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 49990 50010  Amount of Mg in roasted struvite  mg 6501.19 6825.38 7591.83  Amount of Mg in roasted struvite  g 6.50 6.83 7.59  Feed   Conc Mg mg/L 35.81 30.6935 33.017  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 26.8575 23.020125 25  Amount of Mg in feed g 0.0268575 0.023020125 0.02  Total Mg to start g 6.5280 6.8484 7.6166  Proportion of Mass Mg in feed  0.0041142 0.003361385 0.003251158  Proportion of Mg in calcinated pellets  0.9958858 0.996638615 0.996748842  END   Uptake: struvite   Conc Mg mg/L 415.79 485.765 444.44  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 56710 66720 63760  Amount of Mg in struvite after uptake mg 5894.86 8102.56 7084.37  Amount of Mg in struvite after uptake g 5.89 8.10 7.08  Fines   Conc Mg mg/L 350.895 423.33 358.37  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 8740 4100 4930  Amount of Mg in fines mg 766.71 433.91 441.69  Amount of Mg in fines g 0.77 0.43 0.44   Filter Paper   Conc Mg mg/L 232.02 111.3 283.325  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 11.60 5.57 14.17  Amount of Mg in filter paper g 0.01 0.01 0.01   Feed     0 mins Conc Mg mg/L 38.11 18.5435 20.235  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0001906 9.27175E-05 0.000101175       15 mins Conc Mg mg/L 108.915 23.032 14.401  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0005446 0.00011516 0.000072005       30 mins Conc Mg mg/L 131.525 28.1515 20.5035  141   Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0006576 0.000140758 0.000102518       45 mins Conc Mg mg/L 176.04 29.908 23.989  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0008802 0.00014954 0.000119945       60 mins Conc Mg mg/L 209.145 32.0055 27.116  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0010457 0.000160028 0.00013558       75 mins Conc Mg mg/L 242.6 34.4925 28.337  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.001213 0.000172463 0.000141685       90 mins Conc Mg mg/L 255.6 51.5035 31.715  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.001278 0.000257518 0.000158575       105 mins Conc Mg mg/L 194.6 53.9835 34.0485  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.000973 0.000269918 0.000170243       120 mins Conc Mg mg/L 168.02 64.385 36.3155  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.1192942 0.04571335 0.025784005   TOTAL Mg AT END g 6.80 8.59 7.57  Mass Mg remain in soln (g)  0.12 0.05 0.03  Mass in fines + filter (g)  0.78 0.44 0.46  Mass Mg in uptake pellets (g)  5.89 8.10 7.08  Mass Mg lost during sampling (g)  0.01 0.00 0.00  DIFFERENCE g -0.27 -1.74 0.05  Reduction of mass in solution  -0.10 -0.02 0.00  RECOVERY (%)  104 125 99     142  Table B. 18 2009 magnesium balance 200°C  Sample Unit pH 8 pH 9 pH 10  START   Roasted struvite   Conc Mg mg/L 524.615 491.235 52.64  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite for uptake mg 50000 50010 50020  Amount of Mg in roasted struvite  mg 6557.69 6141.67 658.26  Amount of Mg in roasted struvite  g 6.56 6.14 0.66  Feed   Conc Mg mg/L 40.475 29.9265 28.855  Vol. sample L 0.75 0.75 0.75  Amount of Mg in feed mg 30.35625 22.444875 22  Amount of Mg in feed g 0.0303563 0.022444875 0.02  Total Mg to start g 6.59 6.16 0.68  Proportion of Mass Mg in feed  0.0046078 0.003641219 0.03182984  Proportion of Mg in calcinated pellets  0.9953922 0.996358781 0.96817016  END   Uptake: struvite   Conc Mg mg/L 418.05 327.145 57.225  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt struvite after uptake mg 55400 68170 67560  Amount of Mg in struvite after uptake mg 5789.99 5575.37 966.53  Amount of Mg in struvite after uptake g 5.79 5.58 0.97  Fines   Conc Mg mg/L 332.725 360.505 145.39  Vol. sample L 0.05 0.05 0.05  Wt sample for digesting mg 200 200 200  Wt fines mg 7000 2640 2030  Amount of Mg in fines mg 582.27 237.93 73.79  Amount of Mg in fines g 0.58 0.24 0.07   Filter Paper   Conc Mg mg/L 294.7 76.631 11.75  Vol. sample L 0.05 0.05 0.05  Amount of Mg on filter paper mg 14.74 3.83 0.59  Amount of Mg in filter paper g 0.01 0.00 0.00   Feed     0 mins Conc Mg mg/L 37.91 75.7965 29.112  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0001896 0.000378983 0.00014556       15 mins Conc Mg mg/L 156.54 27.3775 38.8465  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0007827 0.000136888 0.000194233       30 mins Conc Mg mg/L 160.205 34.8695 22.452  143   Sample Unit pH 8 pH 9 pH 10  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.000801 0.000174348 0.00011226       45 mins Conc Mg mg/L 159.65 35.626 28.0095  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0007983 0.00017813 0.000140048       60 mins Conc Mg mg/L 183.615 36.01 32.0795  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0009181 0.00018005 0.000160398       75 mins Conc Mg mg/L 187.415 34.855 34.6805  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0009371 0.000174275 0.000173403       90 mins Conc Mg mg/L 227.17 30.58 35.553  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0011359 0.0001529 0.000177765       105 mins Conc Mg mg/L 226.965 30.481 39.0735  Vol. sample L 0.005 0.005 0.005  Ammount of Mg in feed g 0.0011348 0.000152405 0.000195368       120 mins Conc Mg mg/L 208.285 27.4405 39.129  Vol. sample L 0.71 0.71 0.71  Ammount of Mg in feed g 0.1478824 0.019482755 0.02778159   TOTAL Mg AT END g 6.54 5.84 1.07  Mass Mg remain in soln (g)  0.15 0.02 0.03  Mass in fines + filter (g)  0.60 0.24 0.07  Mass Mg in uptake pellets (g)  5.79 5.58 0.97  Mass Mg lost during sampling (g)  0.01 0.00 0.00  DIFFERENCE g 0.05 0.33 -0.39  Reduction of mass in solution  -0.12 0.00 -0.01  RECOVERY (%)  99 95 157    144  Table B. 19 2010 mass balance summary for N, P, and Mg ID Conditions N P Mg 9a Constant pH 8, 2hour, T=105, Mass=20g 94.5 107.5 96.5 9b Constant pH 8, 2hour, T=105, Mass=20g 92.6 107.6 97.6 9c Initial pH 8, 2hour, T=105, Mass=20g 85.7 105.4 97.2 10a Constant pH 8, 2hour, T=105, Mass=20g 110.2 103.0 103.9 10b Rehydration pH 8, 15min, T=105, Mass=20g 110.4 95.0 102.7 10c Constant pH 8, 2hour, T=105, Mass=40g 102.6 102.6 101.7 11a Constant pH 8, 2hour, T=160, Mass=20g 98.9 101.9 99.8 11b Constant pH 8, 2hour, T=160, Mass=40g 97.8 103.7 101.0 11c Initial pH 8, 2hour, T=160, Mass=20g 100.9 72.9 85.9 11d Initial pH 8 filtrate, 30min, T=160, Mass=20g 95.3 91.4 110.7 12a Constant pH 8, 2hour, T=80, Mass=20g 105.7 119.4 120.4 12b Rehydration, 15min, T=80, Mass=5.5g 107.9 202.1 190.7 12c Constant pH 8, 2hour, T=80, Mass=20g 103.8 114.9 119.3 12d Constant pH 8, 2hour, T=80, Mass=40g 104.3 135.5 119.3 15a Constant pH 9, 2hour, T=80, Mass=20g 101.1 104.2 100.9 15b Constant pH 9, 2hour, T=80, Mass=40g 94.9 99.7 101.1 15c Diss-ref pH 9, 2hour, T=80, Mass=20g 99.5 100.9 99.3 16a Diss-ref pH 9, 2hour, T=160, Mass=20g 74.5 84.4 87.8 16b Constant pH 9, 2hour, T=160, Mass=20g 102.2 98.2 100.1 16c Constant pH 9, 2hour, T=160, Mass=40g 81.6 62.9 67.4 17a Diss-ref pH 9, 2hour, T=105, Mass=20g 96.3 98.6 91.4 17b Constant pH 9, 2hour, T=105, Mass=20g 112.8 100.9 165.7 17c Constant pH 9, 2hour, T=105, Mass=40g 122.1 91.4 93.2   145  Table B. 20 2010 nitrogen balance 80°C  Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc N as NH3 mg/L 5.41 5.41 5.41 5.41 4.92 4.92 4.92  Vol. sample 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   Feed   Conc N as NH3 mg/L 703 0.148 661 681 616 636 650  Vol. sample L 0.5 0.5 0.5 0.5 0.5 0.5 0.577  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   END   Uptake: struvite   Conc N as NH3 mg/L 4.47 4.15 4.43 4.33 3.35 3.21 0  Vol. sample 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 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   Fines   Conc N as NH3 mg/L 8.95 0 9.36 9.49 7.58 7.41 4.65  Vol. sample L 0.25 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   Filter Paper   Conc N as NH3 mg/L 0 0 0 0 0 0 0  Vol. sample 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   Feed         0 mins Conc N as NH3 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  146   Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9 15 mins Conc N as NH3 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           30 mins Conc N as NH3 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           45 mins 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           60 mins 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           75 mins 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           90 mins Conc N as NH3 mg/L 572 0 583 476 560 500 0  Vol. sample L 0.005 0.005 0.005 0.005 0.005 0.005 0.005  Ammount of N in feed g 0.00286 0 0.002915 0.00238 0.0028 0.0025 0           105 mins Conc N as NH3 mg/L 559 0 549 474 506 486 0  Vol. sample L 0.005 0.005 0.005 0.005 0.005 0.005 0.005  Ammount of N in feed g 0.002795 0 0.002745 0.00237 0.00253 0.00243 0           120 mins Conc N as NH3 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 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  DIFFERENCE g -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   147  Table B. 21 2010 nitrogen balance 105°C   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c   Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9    START   Roasted struvite   Conc N as NH3 mg/L 6.91 6.91 6.91 5.04 5.04 5.04 3.03 3.03 3.03   Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25   Wt sample for digesting mg 41.2 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    Feed   Conc N as NH3 mg/L 578 677 680 661 3.27 663 767.5 871 939   Vol. sample 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 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    END   Uptake: struvite   Conc N as NH3 mg/L 4.59 4.15 4.87 4.15 3.65 3.66 0 3.97 4.04   Vol. sample 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    Fines   Conc N as NH3 mg/L 7.85 7.5 6.21 8.59 1.18 8.94 5.41 4.81 8.15   Vol. sample L 0.25 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    Filter Paper   Conc N as NH3 mg/L 0 0 0 0 0 0 0 0 0   Vol. sample 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    Feed 0 mins Conc N as NH3 mg/L 712 679 676 679 0 671 1820 868 867  148   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 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 N in feed g 0.00356 0.003395 0.00338 0.003395 0 0.003355 0.0091 0.00434 0.00434  15 mins 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  30 mins 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  45 mins 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  60 mins Conc N as NH3 mg/L 542 537 0 521 0 342 0 814 733   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 0.00271 0.002685 0 0.002605 0 0.00171 0 0.00407 0.00367  75 mins 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  90 mins 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  105 mins 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  120 mins 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   RECOVERY (%)  95 93 86 110 110 103 96 113 122    149  Table B. 22 2010 nitrogen balance 160°C  Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc N as NH3 mg/L 3.57 3.57 3.57 0 2.32 2.32 2.32  Vol. sample L 0.25 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   Feed   Conc N as NH3 mg/L 691 698 673 520 875 699 727  Vol. sample 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   END   Uptake: struvite   Conc N as NH3 mg/L 3.11 2.97 3.27 0 0 2.31 2.06  Vol. sample 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  Amount of N in struvite after uptake g 0.49 0.93 0.53 0.00 0.00 0.33 0.48   Fines   Conc N as NH3 mg/L 8.72 12.5 4.77 8.8 3.92 4.97 5.88  Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25  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  Vol. sample 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   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  150   Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9           15 mins Conc N as NH3 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           30 mins Conc N as NH3 mg/L 462 197 600 215 0 613 558  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           45 mins 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           60 mins 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           75 mins 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           90 mins 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           105 mins 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           120 mins 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  DIFFERENCE g 0.01 0.03 -0.01 0.01 0.20 -0.01 0.17  Reduction of mass in solution  0.17 0.33 0.08 0.13 0.48 0.03 0.09  RECOVERY (%)  99 98 101 95 75 102 82    151  Table B. 23 2010 phosphorus balance 80°C  Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc P as PO4 mg/L 24.3 24.3 24.3 24.3 35.5 35.5 35.5  Vol. sample 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   Feed   Conc P as PO4 mg/L 11 0.382 9.43 35.9 9.2 9.38 9.26  Vol. sample L 0.5 0.5 0.5 0.5 0.5 0.5 0.577  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 mg/L 19.8 35 20.4 23.6 23.5 23.3 0  Vol. sample 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   Fines   Conc P as PO4 mg/L 42.6 0 23.7 26 18.3 18.9 19.4  Vol. sample L 0.25 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   Filter Paper   Conc P as PO4 mg/L 0 0 0 0 0 0 0  Vol. sample 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   Feed         0 mins Conc P as PO4 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  152   Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9           15 mins Conc P as PO4 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           30 mins Conc P as PO4 mg/L 21.4 0 22.9 53.1 2.2 10.9 0  Vol. sample L 0.005 0.005 0.005 0.005 0.005 0.005 0.005  Ammount of P in feed g 0.000107 0 0.0001145 0.0002655 0.000011 0.0000545 0           45 mins Conc P as PO4 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           60 mins 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           75 mins 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           90 mins 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           105 mins 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           120 mins 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  DIFFERENCE g -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    153  Table B. 24 2010 phosphorus balance 105°C   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c   Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9    START   Roasted struvite   Conc P as PO4 mg/L 32.7 32.7 32.7 36.6 36.6 36.6 29.5 29.5 29.5   Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25   Wt sample for digesting mg 41.2 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    Feed   Conc P as PO4 mg/L 8.68 8.94 8.72 9.74 1.21 9.56 10.1 10.7 10.3   Vol. sample 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 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    END   Uptake: struvite   Conc P as PO4 mg/L 23.7 21.7 23.6 24.1 22.8 23.9 0 29.3 24.1   Vol. sample 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    Fines   Conc P as PO4 mg/L 19.5 19.8 19.8 22.1 7.62 20.5 25.4 12.3 19.7   Vol. sample L 0.25 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    Filter Paper   Conc P as PO4 mg/L 0 0 0 0 0 0 0 0 0   Vol. sample 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    Feed 0 mins Conc P as PO4 mg/L 8.68 8.78 38.4 8.97 0 9.21 7300 10.7 10.1  154   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 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  15 mins Conc P as PO4 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  30 mins 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  45 mins 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  60 mins Conc P as PO4 mg/L 54.4 58.1 0 55.7 0 169 0 2.06 3.18   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  75 mins Conc P as PO4 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  90 mins 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  105 mins 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  120 mins 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 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   RECOVERY (%)  108 108 105 103 95 103 99 101 91    155  Table B. 25 2010 phosphorus balance 160°C  Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc P as PO4 mg/L 28.5 28.5 28.5 0 31.5 31.5 31.5  Vol. sample L 0.25 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   Feed   Conc P as PO4 mg/L 8.88 12.2 11.4 686 10.4 10.1 9.99  Vol. sample 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   END   Uptake: struvite   Conc P as PO4 mg/L 21.2 21.6 14.5 0 0 26.6 20.6  Vol. sample 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   Fines   Conc P as PO4 mg/L 20.4 30.4 3.36 20.7 21.8 14.8 16.7  Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25  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   Conc P as PO4 mg/L 0 0 0 0 0 0 0  Vol. sample 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   Feed         0 mins Conc P as PO4 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  156   Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9 15 mins Conc P as PO4 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           30 mins Conc P as PO4 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           45 mins 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           60 mins 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           75 mins 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           90 mins Conc P as PO4 mg/L 87.4 156 622 0 0 5.29 8.11  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           105 mins Conc P as PO4 mg/L 83.8 178 630 0 0 5.28 7.99  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           120 mins Conc P as PO4 mg/L 82.8 190 646 15.6 155 5.15 7.46  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 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  DIFFERENCE g -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    157  Table B. 26 2010 magnesium balance 80°C  Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc N as NH3 mg/L 18.92 18.92 18.92 18.92 27.284 27.284 27.284  Vol. sample 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   Feed   Conc N as NH3 mg/L 34.47 1.2825 31.1425 31.3875 30.6175 31.29 31.1375  Vol. sample L 0.5 0.5 0.5 0.5 0.5 0.5 0.577  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   END   Uptake: struvite   Conc N as NH3 mg/L 15.889 26.106 16.642 16.227 17.5175 18.1975 0  Vol. sample 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 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   Fines   Conc N as NH3 mg/L 15.725556 0 18.04 19.893 13.899 14.684 14.8815  Vol. sample L 0.25 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  Vol. sample 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   Feed         0 mins Conc N as NH3 mg/L 34.835 0 31.4475 31.205 30.8 31.045 5267.75  Vol. sample L 0.005 0.005 0.005 0.005 0.005 0.005 0.005  Ammount of N in feed g 0.0001742 0 0.000157238 0.000156025 0.000154 0.000155225 0.026339  158   Temperature: 80°C  12a 12b 12c 12d 15a 15b 15c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9 15 mins Conc N as NH3 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           30 mins 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           45 mins 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           60 mins 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           75 mins 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           90 mins Conc N as NH3 mg/L 22.905 0 10.625 6.4725 14.3 3.055 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 0.000053125 3.23625E-05 0.0000715 0.000015275 0           105 mins Conc N as NH3 mg/L 21.3125 0 10.015 6.4775 14.055 4.725 0  Vol. sample L 0.005 0.005 0.005 0.005 0.005 0.005 0.005  Ammount of N in feed g 0.0001066 0 0.000050075 3.23875E-05 0.000070275 0.000023625 0           120 mins Conc N as NH3 mg/L 51.1925 46.2875 9.5275 5.745 14.1775 3.3925 50.0375  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  DIFFERENCE g -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    159  Table B. 27 2010 magnesium balance 105°C   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c   Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9    START   Roasted struvite   Conc N as NH3 mg/L 27.2885 27.2885 27.2885 25.666 25.666 25.666 23.0418 23.04175 23.0418   Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25   Wt sample for digesting mg 41.2 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    Feed   Conc N as NH3 mg/L 31.29 31.29 32.8525 30.7775 0 30.8375 30.386 32.00723 31.191   Vol. sample 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 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    END   Uptake: struvite   Conc N as NH3 mg/L 17.9267 16.5768 18.481649 17.17629 17.433299 16.76299 0 37.74607 19.2385   Vol. sample 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    Fines   Conc N as NH3 mg/L 14.4161 14.7172 15.397113 14.82763 5.2668041 15.10485 19.0779 9.76896 14.743   Vol. sample L 0.25 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    Filter Paper   Conc N as NH3 mg/L 0 0 0 0 0 0 0 0 0   Vol. sample 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    Feed 0 mins Conc N as NH3 mg/L 30.6775 30.0675 43.6 30.41 0 30.655 1428.25 31.23025 32.0592  160   Temperature: 105°C   9a 9b 9c 10a 10b 10c 17a 17b 17c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 8 pH 8 pH 9 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 N in feed g 0.000153 0.0001503 0.000218 0.000152 0 0.000153 0.00714 0.000156 0.00016  15 mins Conc N as NH3 mg/L 18.5775 39.905 0 57.4 0 26.135 0 17.77938 13.6194   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  30 mins Conc N as NH3 mg/L 15.155 30.6775 0 35.1725 0 16.1225 0 16.71673 12.6474   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  45 mins Conc N as NH3 mg/L 13.69 22.9775 0 25.8925 0 15.51 0 16.48353 12.4661   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  60 mins Conc N as NH3 mg/L 12.7125 19.0675 0 25.16 0 17.045 0 16.53494 12.3108   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  75 mins Conc N as NH3 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  90 mins Conc N as NH3 mg/L 9.7775 16.3775 0 21.3725 0 14.7075 0 17.98661 12.4921   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  105 mins Conc N as NH3 mg/L 10.145 15.8275 0 20.2725 0 14.4625 0 16.71673 12.1291   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  120 mins Conc N as NH3 mg/L 9.045 15.645 595.7 19.0525 78.53 14.7075 3.595 16.56091 11.9218   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   RECOVERY (%)  96 98 97 104 103 102 91 166 93    161  Table B. 28 2010 magnesium balance 160°C  Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9   START   Roasted struvite   Conc N as NH3 mg/L 26.253 26.253 26.253 0 24.80612 24.80612 24.80612  Vol. sample L 0.25 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   Feed   Conc N as NH3 mg/L 30.215 33.025 33.33 528.48 31.5815 30.824 30.5795  Vol. sample 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   END   Uptake: struvite   Conc N as NH3 mg/L 19.453 19.868 16.4588889 0 0 21.32826 17.36439  Vol. sample 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   Fines   Conc N as NH3 mg/L 15.787 22.434 0.21777778 19.5011111 17.92672 10.971 13.29823  Vol. sample L 0.25 0.25 0.25 0.25 0.25 0.25 0.25  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   Conc N as NH3 mg/L 0 0 0 0 0 0 0  Vol. sample 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   Feed         0 mins Conc N as NH3 mg/L 31.3225 31.19 33.33 0 3605.5 30.9215 30.5795  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  162   Temperature: 160°C  11a 11b 11c 11d 16a 16b 16c  Sample Unit pH 8 pH 8 pH 8 pH 8 pH 9 pH 9 pH 9           15 mins Conc N as NH3 mg/L 183.445 105.065 436.7675 12.9175 0 39.5015 43.8035  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           30 mins Conc N as NH3 mg/L 80.43 106.2875 485.445 8.1675 0 35.5905 40.5035  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           45 mins Conc N as NH3 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           60 mins Conc N as NH3 mg/L 87.02 96.015 493.64 0 0 33.6595 37.9615  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           75 mins Conc N as NH3 mg/L 82.9875 87.575 491.9275 0 0 35 37.7415  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           90 mins Conc N as NH3 mg/L 77.61 89.9 485.69 0 0 125.46 37.096  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           105 mins 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           120 mins Conc N as NH3 mg/L 71.6225 103.5975 496.085 8.9 136.8325 32.486 35.9935  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  DIFFERENCE g 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    163  Appendix C: Elemental analysis spreadsheet  Table C. 1 Elemental analysis solver user input %N = 0.053  user input %H = 0.064  %N + %H (from input) = 0.117  Mass of MgHPO4 = 120.286      Solve%N Equation (Eqn 14) = 0.053 <=go to target cell Solve %H Equation (Eqn 15) = 0.064 <=go to target cell %N + %H (output) = 0.117 <= Target cell soln Input = output= ? = YES  X solved (amount N) = 0.902  Y solved (amount H2O) = 5.705   164  Appendix D: Mass balance graphs   Figure D. 1 2009 nitrogen mass balance @ T=100 for pH 8,9,10   Figure D. 2 2009 nitrogen mass balance @ T=120 for pH 8,9,10  -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  165   Figure D. 3 2009 nitrogen mass balance @ T=140 for pH 8,9,10   Figure D. 4 2009 nitrogen mass balance @ T=160 for pH 8,9,10  -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  166   Figure D. 5 2009 nitrogen mass balance @ T=180 for pH 8,9,10   Figure D. 6 2009 nitrogen mass balance @ T=200 for pH 8,9,10  -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 8 9 10 m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  167   Figure D. 7 2009 phosphorus mass balance @ T=100 for pH 8,9,10   Figure D. 8 2009 phosphorus mass balance @ T=120 for pH 8,9,10  -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g) -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  168   Figure D. 9 2009 phosphorus mass balance @ T=140 for pH 8,9,10   Figure D. 10 2009 phosphorus mass balance @ T=160 for pH 8,9,10  -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g) -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  169   Figure D. 11 2009 phosphorus mass balance @ T=180 for pH 8,9,10   Figure D. 12 2009 phosphorus mass balance @ T=200 for pH 8,9,10  -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g) -1.60 -1.10 -0.60 -0.10 0.40 0.90 1.40 1.90 2.40 8 9 10 m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  170   Figure D. 13 2009 magnesium mass balance @ T=100 for pH 8,9,10   Figure D. 14 2009 magnesium mass balance @ T=120 for pH 8,9,10  0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g) -5.10 -4.10 -3.10 -2.10 -1.10 -0.10 0.90 1.90 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g)  171   Figure D. 15 2009 magnesium mass balance @ T=140 for pH 8,9,10   Figure D. 16 2009 magnesium mass balance @ T=160 for pH 8,9,10  -5.10 -4.10 -3.10 -2.10 -1.10 -0.10 0.90 1.90 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g) -5.10 -4.10 -3.10 -2.10 -1.10 -0.10 0.90 1.90 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g)  172   Figure D. 17 2009 magnesium mass balance @ T=180 for pH 8,9,10   Figure D. 18 2009 magnesium mass balance @ T=200 for pH 8,9,10  -5.10 -4.10 -3.10 -2.10 -1.10 -0.10 0.90 1.90 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g) -5.10 -4.10 -3.10 -2.10 -1.10 -0.10 0.90 1.90 8 9 10 m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g)  173   Figure D. 19 2010 nitrogen mass balance @ T=80   Figure D. 20 2010 nitrogen mass balance @ T=105  -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 12a 12b 12c 12d 15a 15b 15c m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 9a 9b 9c 10a 10b 10c 17a 17b 17c m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g)  174   Figure D. 21 2010 nitrogen mass balance @ T=160   Figure D. 22 2010 phosphorus mass balance @ T=80  -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 11a 11b 11c 11d 16a 16b 16c m as s (g ) pH N loss in solution (g) N in fines + filter (g) N uptake into pellets (g) N Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 12a 12b 12c 12d 15a 15b 15c m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  175   Figure D. 23 2010 phosphorus mass balance @ T=105   Figure D. 24 2010 phosphorus mass balance @ T=160   -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 9a 9b 9c 10a 10b 10c 17a 17b 17c m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 11a 11b 11c 11d 16a 16b 16c m as s (g ) pH P loss in solution (g) P in fines + filter (g) P uptake into pellets (g) P Mass Balance (g)  176   Figure D. 25 2010 magnesium mass balance @ T=80   Figure D. 26 2010 magnesium mass balance @ T=105 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 12a 12b 12c 12d 15a 15b 15c m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g) -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 9a 9b 9c 10a 10b 10c 17a 17b 17c m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g)  177   Figure D. 27 2010 magnesium mass balance @ T=160                              -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50 11a 11b 11c 11d 16a 16b 16c m as s (g ) pH Mg loss in solution (g) Mg in fines + filter (g)  178  Appendix E: Economic analysis  Table E. 1 Heating-reformation method  Struvite price ($/tonne) 3000 Struvite price ($/gram) 0.003 initial mass (g) 50 mass after heat (g) 28.5 mass after uptake (g) 43.3 Mass used per experiment (g) 5.2 Total Struvite cost per batch ($/batch) 0.01554 volume centrate per batch (L/batch) 0.5 Cost per litre ($/litre) 0.03108 Total volume wastewater per day (MLD) 76.2 BOD removed per day (lb/ML) 548.5986 Total volume centrate treated per day (L/Day) 54000 Sludge specific gravity 1.02 water unit weight (lb/ft3) 62.4 BOD utilization rate (lb cells/lb BOD utilized) 0.05 Volume sludge (cubic feet per day) 13135.75 volume centrate per volume sludge 0.75 Volume centrate (liters per day) 278973.8 Cost per day ($/day) 8670.505   Caustic price ($/kg) 0.5 Caustic usage (kg/L) 0.005773 Caustic price ($/L treated) 0.002887 Total caustic price per day ($/day) 805.3043   Electricity price ($/kwh) 0.02817 Power per volume (hp/L) 0.033333 power per volume (kilowatts/L) 0.02486 efficiency (%) 0.9 power drawn per day per litre 0.03 Daily power drawn per litre (kwh/day/l) 0.03 Daily Electricity cost ($/day) 217.07  Labour Cost 120.55  Total Cost per day ($/day) 9813   179   Table E. 2 Sidestream nitrification method  centrate NH3 conc (mg/L) 700 desired NH3 effluent conc (mg/L) 5 NH3 removal desired (mg/L) 695 molar mass NH3 17 molar mass N 14 N removal desired (mg/L) 572.3529 alkalinity consumption (eq CaCO3/mol N) 2 total alkalinity required (mg/L as CaCO3) 4088.235 alkalinity in centrate (mg/L as CaCO3) 100 alkalinity addition required (mg/L as CaCO3) 3988.235 Flow treated (L/day) 278973.8 daily mass CaCO3 requirmennt (kg/day) 1112.613 price CaCO3 ($/kg) 0.3 Daily alkalinity cost ($/day) 334   oxygen requirement (kg/day) 1620 oxygen price ($/kg) 0.2 Daily oxygen cost ($/day) 324   Total Cost per day ($/day) 658  

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China 3 12
France 2 2
India 2 0
Norway 1 0
City Views Downloads
Unknown 38 32
Mountain View 4 0
Warwick 4 0
Tiran 4 0
Halifax 3 0
Beijing 3 0
Tokyo 2 0
Boardman 1 0
Botkins 1 0
Sunnyvale 1 0
Pitt Meadows 1 1
Vieux-Saint-Laurent 1 0
Toronto 1 0

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