{"http:\/\/dx.doi.org\/10.14288\/1.0371026":{"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool":[{"value":"Applied Science, Faculty of","type":"literal","lang":"en"},{"value":"Civil Engineering, Department of","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider":[{"value":"DSpace","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#degreeCampus":[{"value":"UBCV","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/creator":[{"value":"Larson, Sean","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/issued":[{"value":"2020-10-31T07:00:00Z","type":"literal","lang":"en"},{"value":"2018","type":"literal","lang":"en"}],"http:\/\/vivoweb.org\/ontology\/core#relatedDegree":[{"value":"Master of Applied Science - MASc","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#degreeGrantor":[{"value":"University of British Columbia","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/description":[{"value":"The University of British Columbia (UBC) has been researching the removal and recovery of phosphorus and nitrogen from waste water by producing NH\u2084-struvite (MgNH\u2084PO\u2084:6H\u2082O) pellets in their patented Fluidized Bed Reactor (FBR), since the early 2000\u2019s. This work has successfully produced a marketable, slow-release, fertilizer pellet applicable for stream or land application. Potassium is another common fertilizer nutrient, and is present in some waste water streams. However, at this time, little research has been done in incorporating it into the pellets produced by the UBC FBR. Producing a pellet with both NH4-struvite and K-struvite (MgKPO\u2084:6H\u2082O) may hold the potential to produce a full-complement NPK fertilizer.\r\nThe research objectives of this project included furthering the understanding of some basic chemistry properties that might interfere with the formation of K-struvite in practical applications, producing a K-struvite pellet in the UBC FBR, and producing a full-complement struvite pellet in the UBC FBR. Research specifically included bench scale experiments investigating the interference of nitrogen feed products on K-struvite formation; UBC FBR experiments to produce K-struvite pellets; and UBC FBR experiments to produce pellets containing both K-struvite and NH4-struvite.\r\nThe research results indicate that ammonia must be below 5.6 mM to stop significant interference with K-struvite production, with the K-struvite feed concentrations used. Nitrification feed products, nitrate and nitrite, were not shown to interfere with K-struvite production in this research. \r\nBuilding on past UBC research, K-struvite was formed in the UBC FBR. The attempt to pelletize pure K-struvite grown around seed material was successful in the reactor; however it was not successfully harvested, as it was unable to hold its structure when harvesting forces were applied. In further experiments, NH\u2084-struvite was used to coat the K-struvite pellet in the reactor; which allowed the pellet to both, hold structure when harvested, and contain both types of struvite, making it a full-complement NPK fertilizer.\r\nThe range of phosphorus removal in this research varied from 0% to 100%, depending on initial feed and operating conditions. The main variables were pH, presence of ammonia, and hydraulic residence time. Typical K-struvite operation had a phosphorus removal of 60% to 80%.","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO":[{"value":"https:\/\/circle.library.ubc.ca\/rest\/handle\/2429\/66788?expand=metadata","type":"literal","lang":"en"}],"http:\/\/www.w3.org\/2009\/08\/skos-reference\/skos.html#note":[{"value":"      A UBC FLUIDIZED BED REACTOR INVESTIGATION OF K-STRUVITE  by  Sean Larson BSc. Civil-Environmental Engineering, University of Alberta 2012  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMNTS FOR THE DEGREE OF  MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Civil Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  August 2018      \u00a9 Sean Larson, 2018     The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, a thesis\/dissertation entitled:  A UBC FLUIDIZED BED REACTOR INVESTIGATION OF K-STRUVITE  submitted by Sean Larson  in partial fulfillment of the requirements for the degree of Master of Applied Science in The Faculty of Graduate and Postdoctoral Studies (Civil Engineering)  Examining Committee: Dr. Donald Mavinic Supervisor Dr. Al Gibb Co-supervisor     ii      ABSTRACT  The University of British Columbia (UBC) has been researching the removal and recovery of phosphorus and nitrogen from waste water by producing NH4-struvite (MgNH4PO4:6H2O) pellets in their patented Fluidized Bed Reactor (FBR), since the early 2000\u2019s. This work has successfully produced a marketable, slow-release, fertilizer pellet applicable for stream or land application. Potassium is another common fertilizer nutrient, and is present in some waste water streams. However, at this time, little research has been done in incorporating it into the pellets produced by the UBC FBR. Producing a pellet with both NH4-struvite and K-struvite (MgKPO4:6H2O) may hold the potential to produce a full-complement NPK fertilizer. The research objectives of this project included furthering the understanding of some basic chemistry properties that might interfere with the formation of K-struvite in practical applications, producing a K-struvite pellet in the UBC FBR, and producing a full-complement struvite pellet in the UBC FBR. Research specifically included bench scale experiments investigating the interference of nitrogen feed products on K-struvite formation; UBC FBR experiments to produce K-struvite pellets; and UBC FBR experiments to produce pellets containing both K-struvite and NH4-struvite. The research results indicate that ammonia must be below 5.6 mM to stop significant interference with K-struvite production, with the K-struvite feed concentrations used. Nitrification feed products, nitrate and nitrite, were not shown to interfere with K-struvite production in this research.  Building on past UBC research, K-struvite was formed in the UBC FBR. The attempt to pelletize pure K-struvite grown around seed material was successful in the reactor; however it was not successfully harvested, as it was unable to hold its structure when harvesting forces were applied. In further experiments, NH4-struvite was used to coat the K-struvite pellet in the reactor; which allowed the pellet to both, hold structure when harvested, and contain both types of struvite, making it a full-complement NPK fertilizer. The range of phosphorus removal in this research varied from 0% to 100%, depending on initial feed and operating conditions. The main variables were pH, presence of ammonia, and hydraulic residence time. Typical K-struvite operation had a phosphorus removal of 60% to 80%.  iii       LAY SUMMARY  The University of British Columbia (UBC) NH4-struvite (MgNH4PO4:6H2O) pellets, produced in their patented Fluidized Bed Reactor (FBR), remove and recover phosphorus and nitrogen from waste water. This marketable, slow-release, fertilizer pellet is applicable for stream or land application. The research objective was to incorporate potassium, another common fertilizer nutrient, into the pellets produced by the UBC FBR.  Research investigated the interference of nitrogen products on K-struvite (MgKPO4:6H2O) formation; K-struvite pellet production in the UBC FBR; and combined K-struvite and NH4-struvite UBC FBR pellet production. The research found a lower limit of ammonia interference with K-struvite production, and confirmed nitrification products would not interfere with K-struvite production.   K-struvite was formed in the UBC FBR; however due to its weak structure, was not successfully harvested. Later, NH4-struvite was used to coat the K-struvite pellet in the reactor; creating a pellet both able to be harvested, and containing both types of struvite. iv       PREFACE  This thesis is unpublished research performed independently by the author.  Research topics and ideas are expanded and formulated from Aline Bennet\u2019s 2015 UBC K-struvite research, and Marcia Fromberg\u2019s current UBC NH4-struvite research. Dr. Sergey Lobanov supplied PHREEQC models used to estimate supersaturation ratio\u2019s.   v     TABLE OF CONTENTS  ABSTRACT ..................................................................................................................................................... iii LAY SUMMARY ............................................................................................................................................. iv PREFACE ........................................................................................................................................................ v TABLE OF CONTENTS .................................................................................................................................... vi LIST OF TABLES .............................................................................................................................................. x LIST OF FIGURES ........................................................................................................................................... xi LIST OF ABBREVIATIONS AND SYMBOLS ..................................................................................................... xiv ACKNOWLEDGEMENTS ............................................................................................................................... xv CHAPTER 1: INTRODUCTION ......................................................................................................................... 1 CHAPTER 2: BACKGROUND ........................................................................................................................... 2 2.1 Potassium in the Environment ............................................................................................................ 2 2.2 Phosphorus in the Environment ......................................................................................................... 2 2.3 Nutrient Recovery Research at UBC ................................................................................................... 3 2.3.1 NH4 struvite .................................................................................................................................. 3 2.3.2 Full Compliment NPK Fertilizer .................................................................................................... 3 2.3.3 K struvite ...................................................................................................................................... 3 2.4 Sources for Recovery of Potassium, Phosphorus, and Nitrogen ........................................................ 3 2.5 K-struvite ............................................................................................................................................. 4 2.5.1 Chemical formula ......................................................................................................................... 4 2.5.2 Crystal Structure .......................................................................................................................... 4 2.5.3 Other compounds that could form .............................................................................................. 5 2.5.4 Supersaturation ........................................................................................................................... 6 2.5.5 Impacts of nitrogen compounds .................................................................................................. 7 2.5.6 What makes a struvite pellet grow .............................................................................................. 8 2.6 The UBC FBR ........................................................................................................................................ 8 2.6.1 NH4-struvite................................................................................................................................ 10 2.6.2 K-struvite .................................................................................................................................... 10 2.7 PHREEQC Modelling .......................................................................................................................... 11 2.8 UBC K-struvite Research Building Blocks .......................................................................................... 11 2.9 Conclusions ....................................................................................................................................... 13vi    TABLE OF CONTENTS   CHAPTER 3: RESEARCH OBJECTIVES............................................................................................................ 14 CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF NITROGEN PRODUCTS ON K-STRUVITE FORMATION .............. 15 4.1 Objectives.......................................................................................................................................... 15 4.2 Materials and Methods ..................................................................................................................... 15 4.2.1 Materials and equipment .......................................................................................................... 15 4.2.1.1 Batch Test method and apparatus .......................................................................................... 15 4.2.1.2 Reagents used ......................................................................................................................... 16 4.2.1.3 pH and Conductivity monitoring ............................................................................................. 16 4.2.1.4 Sample collection and preservation ....................................................................................... 16 4.2.2 Analytical methods .................................................................................................................... 16 4.2.2.1 Magnesium analysis ................................................................................................................ 16 4.2.2.2 Phosphate analysis .................................................................................................................. 16 4.2.2.3 Potassium analysis .................................................................................................................. 16 4.2.2.5 X-Ray diffraction analysis ........................................................................................................ 17 4.2.3. Quality assurance & statistical methods ................................................................................... 17 4.2.4 Experimental setup .................................................................................................................... 17 4.2.5 Experimental procedure ............................................................................................................ 17 4.2.5.1 Optimal concentration ............................................................................................................ 17 4.3 Results and Discussion ...................................................................................................................... 18 4.4 Conclusions ....................................................................................................................................... 21 CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR ....................................................................... 22 5.1 Objectives.......................................................................................................................................... 22 5.2 Materials and Methods ..................................................................................................................... 23 5.2.1 Materials and equipment .......................................................................................................... 23 5.2.1.1 Reagents used ......................................................................................................................... 23 5.2.1.2 Reactor monitoring ................................................................................................................. 23 5.2.1.3 Sample collection and preservation ....................................................................................... 23 5.2.2 Analytical methods .................................................................................................................... 24 5.2.3. Quality assurance & statistical methods ................................................................................... 24 5.2.4 Experimental setup .................................................................................................................... 24 5.3 Run 1 ................................................................................................................................................. 26 5.3.1 Run 1 Synthetic Feed Composition ............................................................................................ 26 vii    TABLE OF CONTENTS   5.3.2 Run 1 Reactor Operation ........................................................................................................... 26 5.3.3 Run 1 Results and Discussion ..................................................................................................... 27 5.4 Run 2 ................................................................................................................................................. 29 5.4.1 Run 2 Synthetic Feed Composition ............................................................................................ 29 5.4.2 Run 2 Reactor Operation ........................................................................................................... 29 5.4.3 Run 2 Results and Discussion ..................................................................................................... 30 5.5 Run 3 ................................................................................................................................................. 32 5.5.1 Run 3 Synthetic Feed Composition ............................................................................................ 32 5.5.2 Run 3 Reactor Operation ........................................................................................................... 32 5.5.3 Run 3 Results and Discussion ..................................................................................................... 33 5.6 Run 4 ................................................................................................................................................. 36 5.6.1 Run 4 Synthetic Feed Composition ............................................................................................ 36 5.6.2 Run 4 Reactor Operation ........................................................................................................... 36 5.6.3 Run 4 Results and Discussion ..................................................................................................... 37 5.7 Run 5 ................................................................................................................................................. 38 5.7.1 Run 5 Synthetic Feed Composition ............................................................................................ 38 5.7.2 Run 5 Reactor Operation ........................................................................................................... 39 5.7.3 Run 5 Results and Discussion ..................................................................................................... 39 5.8 Run 6 ................................................................................................................................................. 40 5.8.1 Run 6 Synthetic Feed Composition ............................................................................................ 40 5.8.2 Run 6 Reactor Operation ........................................................................................................... 41 5.8.3 Run 6 Results and Discussion ..................................................................................................... 41 5.9 Run 7 ................................................................................................................................................. 42 5.9.1 Run 7 Synthetic Feed Composition ............................................................................................ 42 5.9.2 Run 7 Reactor Operation ........................................................................................................... 43 5.9.3 Run 7 Results and Discussion ..................................................................................................... 44 5.10 Struvite crystal morphology ............................................................................................................ 46 5.11 Conclusions ..................................................................................................................................... 47 CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS ............................................................................. 48 6.1 Conclusions ....................................................................................................................................... 48 6.2 Recommendations for Future Work ................................................................................................. 49 REFERENCES ................................................................................................................................................ 51 viii    TABLE OF CONTENTS   APPENDIX A \u2013 Experiment 1: Benchtop Chemistry Experiment Data......................................................... 58 APPENDIX B \u2013 Experiment 1: Benchtop Chemistry Experiment Solids Analysis ......................................... 59 APPENDIX C \u2013 Experiment 2: UBC FBR Experiment Data ............................................................................ 63 APPENDIX D \u2013 Experiment 2: UBC FBR Experiment Solids Analysis............................................................ 70  ix    LIST OF TABLES  Table 1 \u2013 Average nutrient concentrations in wastes with potential for struvite production  (Bennet 2015)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026....4 Table 2: Approximation of Activity Coefficient (Bennet 2015)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.7 Table 3: Experimentally determined pKsp at 25\u00b0C for K-struvite and NH4 struvite (Bennet 2015)\u2026\u2026\u2026\u2026..7 Table 4 - operation and performance for UBC-FBR NH4-struvite crystallizer from pilot studies  (Bennet 2015)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..10 Table 5 - Summary of experiment 2 parameters for K-struvite synthesis batch tests (Bennet 2015)\u2026\u2026..12 Table 6: Benchtop Experiment Additives\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.18 Table 7 \u2013 Experiment 2 Run Objectives\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.22 Table 8 - Run 1 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202627 Table 9 - Run 2 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202629 Table 10 - Run 3 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.33 Table 11 - Run 4 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.37 Table 12 - Run 5 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.39 Table 13 \u2013 Run 6 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202641 Table 14 \u2013 Run 7 average operating parameters\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202644 Table A1 \u2013 Experiment 1 Monitoring Data and Results\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.58 Table B1 \u2013 Experiment 1 Solids Analysis Data and Results\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..59 Table C1 \u2013 Experiment 2 Monitoring and Operation Data \u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..63 Table C2 \u2013 Experiment 2 Sample Data \u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..66 Table C3 \u2013 Experiment 2 Results\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202669 Table D1 \u2013 Experiment 2 Solids Analysis Data and Results\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..70  x    LIST OF FIGURES Figure 1 (Bennet 2015) \u2013K-struvite crystals are typically characterized by an orthorhombic,  needle-like structure (Wilsenach et al. 2007)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..\u2026\u2026\u2026\u2026\u2026\u20265 Figure 2 \u2013 NH4 struvite crystal formed in high supersaturation solution (pH>8) (Abbona and  Boistelle 1979)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u20265 Figure 3: Typical UBC FBR set up (Bennet 2015)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u20269 Figure 4 - UBC-FBR injection port design (Fattah 2004)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u20269 Figure 5 - Optimizing the K:P ratio for low concentration K-struvite synthesis at pH 8.0, [P-PO4] =  8 mM (Bennet 2015)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..12 Figure 6: Two 500mL flasks, run in parallel, stirred, and kept in a temperature controlled 25\u00b0C  bath. Other associated monitoring tools, reagents, and sampling tools at the bench\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.15 Figure 7 \u2013 Experiment 1 sample SL7A4 (x10 magnification), fine needle-like crystals\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.19 Figure 8: Average % Phosphorus Removal in Experiment 1\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202620 Figure 9: Average Solids Produced In Experiment 1\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.20 Figure 10: General Schematic of the UBC FBR\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..25 Figure 11: Indoor set-up of the UBC FBR\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..25 Figure 12 \u2013 Run 1 Start-up, precipitates forming\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202628 Figure 13 \u2013 Run 1, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..28 Figure 14 \u2013 Run 1, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..28 Figure 15 \u2013 Run 1, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)\u2026\u2026\u2026\u2026\u2026\u2026.28 Figure 16 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202630 Figure 17 - Run 2, K-struvite forming around brown NH4-struvite seeds in Fine zone. Colour  difference noticeable from seeds that have settled on the lip at the bottom of the Fine zone\u2026\u2026\u2026\u2026\u2026\u202630 Figure 18 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202631 Figure 19 \u2013 Run 2, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)\u2026\u2026\u2026\u2026\u2026\u2026.31 Figure 20 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202631 Figure 21 \u2013 Reactor pH influence on solution supersaturation ratio (Sk)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.33 Figure 22 \u2013 pH impact to Phosphorus removal in the UBC FBR, Runs 1-3\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.\u202634 Figure 23 - Run 3, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202635 Figure 24 \u2013 Run 2, harvested pellets (bottom), compared to brown NH4-struvite seeds (top) \u2026\u2026\u2026\u2026\u2026\u202635 xi    LIST OF FIGURES   Figure 25 - Run 3, K-struvite forming around brown NH4-struvite seeds in Fine zone. Colour  difference noticeable from seeds that have settled on the lip at the bottom of the Fine zone\u2026\u2026\u2026\u2026\u2026\u202635 Figure 26 \u2013 Run 4, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)\u2026\u2026\u2026\u2026\u2026\u2026.38 Figure 27 \u2013 Run 5, harvested pellets (bottom), compared to brown NH4-struvite seeds (top) \u2026\u2026\u2026\u2026\u2026\u202640 Figure 28 - Run 5, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202640 Figure 29 \u2013 Run 6, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)\u2026\u2026\u2026\u2026\u2026\u2026.42 Figure 30 - Run 6, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202642 Figure 31 \u2013 Run 7, harvested pellets (bottom), compared to brown NH4-struvite seeds (top) \u2026\u2026\u2026\u2026\u2026..45 Figure 32 - Run 7, K-struvite forming around brown NH4-struvite seeds in active zone\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202645 Figure 33 \u2013 Run 7, harvested and sieved pellets (1mm, 0.5mm, and <0.5mm)\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202645 Figure 34 \u2013 Run 2, sample SL14_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.46 Figure 35 \u2013 Run 7, sample SL50_2A \u2013 NH4-struvite and K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202647 Figure B1: Solids Molar Ratio of K and N-NH4 to P in Run 1, Experiment 1\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.59 Figure B2 \u2013 Experiment 1, sample SL7A4 \u2013 K-struvite and Cattiite \u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202660 Figure B3 \u2013 Experiment 1, sample SL12A4 \u2013 NH4-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..60 Figure B4 \u2013 Experiment 1, sample SL17A4 \u2013 K-struvite and Cattiite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.61 Figure B5 \u2013 Experiment 1, sample SL22A4 \u2013 K-struvite and Cattiite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.61 Figure B6 \u2013 Experiment 1, sample SL27A4 \u2013 K-struvite and Cattiite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.62 Figure D1 \u2013 Experiment 2, Run 1, Sample SL9_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.70 Figure D2 \u2013 Experiment 2, Run 2, Sample SL14_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..71 Figure D3 \u2013 Experiment 2, Run 2, Sample SL16_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..71 Figure D4 \u2013 Experiment 2, Run 3, Sample SL22_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..72 Figure D5 \u2013 Experiment 2, Run 3, Ssample SL24_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u202672 Figure D6 \u2013 Experiment 2, Run 3, Sample SL26_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..73 Figure D7 \u2013 Experiment 2, Run 4, Sample SL32_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..73 Figure D8 \u2013 Experiment 2, Run 5, Sample SL38_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..74 Figure D9 \u2013 Experiment 2, Run 6, Sample SL44_2A \u2013 K-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026..74 Figure D10 \u2013 Experiment 2, Run 7, Sample SL50_2A \u2013 K-struvite and NH4-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.75 xii    LIST OF FIGURES   Figure D11 \u2013 Experiment 2, Run 7, Sample SL50_2A \u2013 K-struvite and NH4-struvite\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.75 xiii    LIST OF ABBREVIATIONS AND SYMBOLS  CRT   Crystal retention time EC   Electrical conductivity FBR   Fluidized bed reactor HRT   Hydraulic retention time K-struvite  MgKPO4:6H2O (Potassium-Struvite) Ksp,   Solubility product Ksp-K   Solubility product of K-struvite NPK   Nitrogen, phosphorus and potassium NH4-struvite  MgNH4PO4:6H2O (Ammonia-Struvite) pKsp   -log10(Ksp) pKsp-K   -log10(Ksp-K) PHREEQC  Aqueous equilibrium modelling software developed by the US Geological Survey S   Supersaturation ratio SK   K-struvite supersaturation ratio, Equation 6 SI   Saturation index UBC   University of British Columbia WWTP   Waste water treatment plant \u03bc   Ionic strength  xiv    ACKNOWLEDGEMENTS  Supervisors Dr. Donald Mavinic (UBC) and Dr. Al Gibb (WSP-OPUS) for their mentorship and guidance Marcia Fromberg and Aline Bennett for their support with background information, hypothesis, modelling, experiment set-up, and operations Tim Ma and Otman Abida for their assistance with lab work and advice on methods The Natural Sciences and Engineering Research Council of Canada for funding this work. My family and friends for support My past teachers and mentors, including Dr. Don Flaten, for their mentorship and guidance, introducing me to the field of Environmental Engineering at a young age  xv   This work is dedicated to The University of British Columbia\u2019s School of Civil Engineering, specifically the Pollution Control and Water Management (PCWM) group, whose past research in the field of nutrient recovery from waste water inspired me at a young age to pursue a career in Environmental Engineering.  xvi   CHAPTER 1: INTRODUCTION   Potassium is used mainly to produce fertilizers, with about 95% of all potassium chloride, also known as potash, produced for this purpose (CCME 2008). Potassium is essential for plant and animal nutrition, readily accumulated and considered one of the most important nutrients in plant and animal health, after nitrogen and phosphorus (Bowen 1979). Winter hardiness, pest resistance, drought tolerance, and disease resistance are all linked to potassium levels in plants (Brady and Weil 2008). The US Geological Survey estimates that global consumption will increase from 39 million metric tons (MT) in 2016 to 43 million MT in 2019. Canada is the world\u2019s largest producer of potash at 10 million MT, with most Canadian production found in Saskatchewan (CCME 2008). There is no known potassium based municipal waste water regulation. NH4-struvite research began at the University of British Columbia (UBC) in 2000 and resulted in technology for the recovery of phosphorus; it was commercialized in 2005 by producing struvite pellets, as part of Ostara\u2019s Pearl\u00a9 Process (BCWWA 2016). Struvite was recognized as an ideal fertilizer due to its chemical make-up of Mg:N:P (1:1:1M) and low solubility, characterizing it as a slow release fertilizer. The first research focus was on NH4-struvite, since the removal of phosphorus and ammonia is usually required in waste water treatment and this form of struvite is the most commonly occurring. The three main nutrients that support plant growth are nitrogen, phosphorus and potassium (NPK). Producing a full-complement NPK slow release fertilizer is a new focus at UBC, by attempting to incorporate both NH4-struvite and K-struvite into one pellet. Adding potassium to the pellet structure will add value to the regular NH4-struvite process. In agricultural applications, it may also prevent the buildup of potassium in local biospheres, where feed is imported and waste is spread on agricultural land. Bennet (2015), suggests that agricultural waste streams have the best advantage of producing a full-complement NPK fertilizer, as they contain all three nutrients, as well as the magnesium needed to complete the struvite chemical structure. Human waste streams generally would require supplementing one or more constituents of struvite, especially potassium. K-struvite has been synthesized in laboratory conditions to show its viability for phosphorus and potassium removal from waste waters (Bennet 2015, Zeng & Li 2006, Wilsenach 2007 and Satoshi et al. 2013). Bennet (2015) was the first to attempt producing a K-struvite pellet using the UBC Fluidized Bed Reactor (FBR). The first attempt to use the UBC FBR to pelletize K-struvite was unsuccessful, and remained largely untested. This current work is the second attempt at using the UBC FBR, to pelletize K-struvite.  The research objectives of this project were to further the understanding of some of the basic chemistry properties that might interfere with the formation of K-struvite in practical applications, produce a K-struvite pellet in the UBC FBR, and produce a full-complement struvite pellet in the UBC FBR. This entailed specifically researching the interference of ammonia and nitrification products on K-struvite formation through bench scale experiments, undertaking experiments in the UBC FBR to produce K-struvite pellets, and undertaking experiments in the UBC FBR to produce pellets containing both K-struvite and NH4-struvite. 1   CHAPTER 2: BACKGROUND  2.1 Potassium in the Environment  Potassium makes up roughly 2.5% of the earth\u2019s crust and is a main alkali metal found in water, but is naturally found to be generally less than 10 mg\/L in surface waters (McNeely et al 1979). Most soils contain 1-2% potassium (NRCC 1977). Potassium is largely used to produce basic fertilizer, and is marketed as potash. Canada is the world\u2019s largest producer of potash, with reserves estimated to last for approximately 400 years at current production. Russia, Belarus and China also have significant reserves of potash. Potassium is predominantly found in ionic form in water, and can readily be incorporated into new mineral structures (McNeely et al 1979). When potassium is over applied to crops, plants have been shown to uptake excess quantities of the nutrient (Brad and Weil 2008). Potassium rich feed crops can cause calving and milking problems in dairy cattle, when the excess potassium interferes with calcium and magnesium uptake (Schmidt et al 2010). Nutrient buildup can be an issue on dairy farms with a small land base, feeding imported and locally grown crops, and land spreading the manure to grow the local feed crop (Bennett 2015). Smil (1999) and Manning (2011) discuss the insufficient level of potassium in some parts of the world. The deficit of potassium in developing countries especially can be large, because it can be expensive and inaccessible to local farmers. Smil (1999) found that potassium is applied at a rate that replenishes only 35% of the potassium removed by crop harvesting, on average. Development of less expensive and more accessible fertilizers therefore could help alleviate this issue.   2.2 Phosphorus in the Environment  Phosphorus may naturally be released into the environment through weathering of phosphate containing rocks; however due to active plant uptake, it is seldom found in high concentrations. Phosphorus concentrations between 0.01 and 0.05 mg\/L are common in surface and ground waters. Water draining from phosphate rock areas and lakes with rich organic matter may contain elevated levels (CEME 2008). Phosphorus can exist in various oxidation states, organic and inorganic forms, and form dissolved or particulate species.  These various states of existence are highly dependent on pH and the presence of other matter.  Phosphate is largely used to produce fertilizers; in Canada, this accounts for about 75% phosphate rock use (CCME 2008). The US Geological Survey estimates that global consumption will increase from 44.5 million metric tons (MT) in 2016 to 48.9 million MT in 2020. China, Morocco, and Russia make up roughly 95% of the global phosphate production.  Canada is not a significant producer of phosphate, and currently, Canadian production only occurs in Quebec (Mavinic 2018).2   CHAPTER 2: BACKGROUND  Phosphorus is an essential micronutrient and is readily accumulated by a variety of organisms (Bowen 1979). Considered one of the most important nutrients in plant and animal health, it can be a limiting nutrient for growth. Elevated concentrations of phosphorus can lead to accelerated eutrophication (Wetzel 1975). Phosphorus is a nutrient that is regulated in municipal waste water, with a required discharge limit of 1 mg\/L for Total Phosphorus (AEP 2018, BC MWR 2018).   2.3 Nutrient Recovery Research at UBC  In 2018, the Pollution Control and Water Management (PCWM) group at the University of British Columbia (UBC) will be celebrating 50 years of excellence in research and teaching. In 1985, UBC developed a pilot-scale biological nutrient removal (BNR) waste water treatment plant at their Staging Environment Research Centre (SERC) (BCWWA 2016). The pilot plant has since been used to develop various technologies to chemically precipitate phosphorus and nitrogen in the form of struvite. This patented technology is marketed under the Ostara Pearl\u00a9 Process.  2.3.1 NH4 struvite Struvite research began at UBC in 2000 and resulted in patented technology for the recovery of phosphorus that was commercialized in 2005, by producing struvite pellets. This research, started with a grant from BC Hydro, attempted to develop a replacement product to fertilize nutrient deficient streams that were no longer able to sustain returning salmon populations. At that time, struvite was recognized as a waste water treatment plant issue, causing problematic scale buildup in plant piping and other infrastructure. Struvite production in pellet form was recognized as an ideal solution, due to its chemical make-up of Mg:N:P (1:1:1M) and low solubility (slow release fertilizer). 2.3.2 Full Compliment NPK Fertilizer Recently, the goals in this research field have shifted to attempt to incorporate potassium into this slow release fertilizer. As previously stated, the three main nutrients that support plant growth are nitrogen, phosphorus and potassium (NPK). Producing a full-complement NPK fertilizer is now an ongoing research objective.  2.3.3 K struvite Currently, there is significant research at UBC in the area of K-struvite to recover potassium. This research strives to better understand the chemistry behind K-struvite and how to produce commercialized pellets. K-struvite, similar to NH4-struvite has a desired low solubility and chemical composition of Mg:K:P (1:1:1 M). It also has a high market value in the agricultural area (Mavinic 2018)  2.4 Sources for Recovery of Potassium, Phosphorus, and Nitrogen  Table 1 gives an average nutrient concentrations of various wastes that could be considered for struvite production. The ratios of these nutrients are not ideal for immediate production of both NH4 and K struvite. Either pre-processing and\/or nutrient supplementing is anticipated to be required to produce a 3   CHAPTER 2: BACKGROUND  pellet with both NH4 and K struvite. Bennet (2015), suggests that agricultural waste streams have the best advantage of producing a full-complement NPK fertilizer because it has all three nutrients, as well as magnesium. Human waste streams comparatively, may require more nutrient supplementing for both NH4 and K struvite production. Table 1 \u2013 Average nutrient concentrations in wastes with potential for struvite production (Bennet 2015) Waste material N-NH4 (mg\/L) P-PO4 (mg\/L) K (mg\/L) Mg (mg\/L) pH Reference Anaerobic digester centrate 1290 108 150 1 - Bhuiyan et al. 2007 Potash tailings brine* - - ~42,000 - - Godwin 2014 Membrane concentrate from landfill leachate treatment  44.7  -  2806  -  7.7  Wang et al., 2012 Untreated swine manure 2342 969 2342 565 7.5  American Society of Agricultural Engineers, 2003 Untreated dairy manure 700 540 2569 629 7.0 Untreated chicken manure 3183 1394 4547 2122 6.9  Concentrate from beet processing 3.7 g organic N\/100g solids  -  9.0 g\/100g solids K2O 0.03 g\/100g solids  -  Decloux et al., 2002 Human urine (synthetic) 266 633 1642 78 5.8 Tilley et al. 2008  Palm oil mill effluent  35  180  2270  615  4.7 Ahmad and Chan, 2009  2.5 K-struvite  2.5.1 Chemical formula K-struvite is magnesium potassium phosphate hexahydrate (MgKPO4:6H2O). It is called K-struvite because the K replaces the NH4 in struvite (Mg NH4PO4:6H20). K-struvite has been found to be naturally occurring under the right conditions (Graeser et al 2008). The general reaction to produce K-struvite is shown in Equation 1: Mg+2 + K+ + PO4-3 + 6H2O \u2194 MgKPO4:6H2O  Equation 1  2.5.2 Crystal Structure K-struvite forms a white crystalline solid. It has been reported to typically have a needle-like orthorhombic structure as shown in Figure 1 (Chauhan et al 2011; Mathew and Schroeder 1979; Satoshi et al. 2013; Wilsenach et al 2007).  4   CHAPTER 2: BACKGROUND   Figure 1 (Bennet 2015) \u2013K-struvite crystals are typically characterized by an orthorhombic, needle-like structure (Wilsenach et al. 2007) In comparison, NH4 \u2013 struvite is reported to be polar (Romanowski et al 2010), forming a variety of crystal shapes depending on the supersaturation of the solution (Abbona and Boistelle 1979). In UBC struvite research, high supersaturation ratios, to obtain branching struvite crystals, is reportedly desired, as shown in Figure 2.   Figure 2 \u2013 NH4 struvite crystal formed in high supersaturation solution (pH>8) (Abbona and Boistelle 1979) 2.5.3 Other compounds that could form  In attempting to produce K-struvite, magnesium chloride, potassium chloride, potassium phosphate, and sodium hydroxide are mixed together. It is important to control mixing conditions; Bennet (2015) reports the potential to form other solid phases, depending on pH, temperature, and chemical concentrations, which include the following:        5   CHAPTER 2: BACKGROUND  K-struvite      MgKPO4:6H2O Brucite      Mg(OH)2 Cattiite      Mg3(PO4)2:22H2O Bobierrite     Mg3(PO4)2:8H2O Newberyite     MgHPO4:3H2O Dimagnesium potassium hydrogen   Mg2KH(PO4)2:15H2O bisphosphate pentadecahydrate (MPHP) Hazenite     Mg2KNa(PO4)2:14H2O Kovdorskite     Mg2PO4OH:3H2O  2.5.4 Supersaturation Supersaturation ratio (S) measures the crystallization potential of the solution. Solutions with a value greater than 1 indicate that precipitation of the solid will occur. The S of the compound of interest being higher than other compounds, not of interest, could indicate that the compound of interest will preferentially form (Bennet 2015).  S is impacted by the solutions chemical concentrations, ionic strength, pH, and solution temperature as discussed in this section. The Supersaturation Ratio of K-struvite (Sk) can be calculated using Equation 2 (Bennet 2015). Sk = \ufffd\u03b3\ufffd\ud835\udc40\ud835\udc40\ud835\udc40\ud835\udc402+\ufffd\u03b3[\ud835\udc3e\ud835\udc3e+]\u03b3[PO4\u22123]\ud835\udc3e\ud835\udc3e\ud835\udc60\ud835\udc60\ud835\udc60\ud835\udc60\u2212\ud835\udc58\ud835\udc58\ufffd1 3\u2044    Equation 2 where:  \u03b3 : activity coefficient [x]: concentration (mol\/L)  Ksp-k: solubility product of K-struvite The activity coefficient is found by first calculating the ionic strength by using the Debye-H\u00fcckel formula for ionic strength (Equation 3) or using the approximation using electrical conductivity (Equation 4) (Bennet 2015). \u03bc =  1 2\ufffd \u2211 C\ud835\udc56\ud835\udc56\ud835\udc4d\ud835\udc4d\ud835\udc56\ud835\udc562       Equation 3 where:  \u03bc:ionic strength c : concentration of species, i z : charge of species, i  or \u03bc = 1.6x10-5 \u00d7 \ud835\udc38\ud835\udc38\ud835\udc36\ud835\udc36      Equation 4 where:  EC: electrical conductivity (\u03bcS\/cm) Then the activity coefficient can be approximated from one of the following four equations, depending on the ionic strength of the solution.   6   CHAPTER 2: BACKGROUND  Table 2: Approximation of Activity Coefficient (Bennet 2015).  Approximation Equation Ionic strength range Debye-H\u00fcckel limiting law approximation    \u03bc < 0.001 Extended Debye-H\u00fcckel approximation   \u03bc < 0.1  G\u00fcntelberg approximation   \u03bc ~ 0.1 - 0.5  Davies approximation   \u03bc < 0.5 A, B \u2013 constants that depend on solvent and temperature (Snoeyink and Jenkins 1980) \u03b1, b \u2013 a constant that relates to the diameter of the hydrated ion; for monovalent ions, usually about 3 to 4E8 (Snoeyink and Jenkins 1980) The Solubility Product of K-struvite Ksp-k can be found in the literature. The published values of K-struvite and NH4 struvite solubility products are shown in Table 3; it can be seen that the latter is slightly less soluble. Table 3: Experimentally determined pKsp at 25\u00b0C for K-struvite and NH4 struvite (Bennet 2015) Solid phase pKsp = -logKsp Reference K-struvite 11.00 Bennet 2015 MgKPO4:6H2O 10.62 A.W. Taylor et al. 1963  NH4-struvite 13.15 A.W. Taylor et al. 1963 13.26 Ohlinger et al. 1998 MgNH4PO4:6H2O 13.36 Bhuiyan et al. 2007 13.47 Lobanov et al. 2013  The solubility product is governed by the Van\u2019t Hoff relationship (Equation 5). This relationship calculates the change of the solubility product constant with a change in temperature.  \ud835\udc59\ud835\udc59\ud835\udc59\ud835\udc59 \ufffd\ud835\udc3e\ud835\udc3e2\ud835\udc3e\ud835\udc3e1\ufffd =  \u2212 \u2206\ud835\udc3b\ud835\udc3b\u00b0\ud835\udc45\ud835\udc45\ufffd1\ud835\udc47\ud835\udc472\u2212  1\ud835\udc47\ud835\udc471\ufffd    Equation 5 where:   \u0394\ud835\udc3b\ud835\udc3b\u00b0: enthalpy of reaction, J\/mol R: universal gas constant, 8.314 J\/mol\u00b7K T: reaction temperature, K  2.5.5 Impacts of nitrogen compounds When considering the production of a full-complement NPK fertilizer, using both struvite and K-struvite from agricultural waste, the impacts of nitrogen products such as ammonia, nitrate, and nitrite on K-struvite must be considered. In the presence of ammonia, struvite is formed preferentially over K-7   CHAPTER 2: BACKGROUND  struvite, due to kinetics and thermodynamics (Satoshi et al 2013). Satoshi et al (2013) also reported that with ammonia concentrations below 1.1mM, reductions of magnesium, potassium and phosphorus were similar to ratio\u2019s found in K-struvite. They did not find that nitrates interfered with K-struvite formation.  2.5.6 What makes a struvite pellet grow  It is accepted that crystal growth in the UBC Fluidized Bed Reactor (FBR) is due to crystal nucleation, crystal growth, and agglomeration. Crystal nucleation and growth are highly dependent on mixing energy and the supersaturation ratio in solution; whereas, agglomeration is due to particle collisions caused by mixing energy, hydrodynamics and attractive forces, such as van der Waals forces (Bennet 2015). A high pH can increase the surface charge of the polar struvite crystals, thus leading to less chance of agglomeration (Bouropoulos and Koutsoukos 2000; Le Corre et al. 2007). A high pH may also correspond to a high supersaturation ratio, reported to favour the formation of fine crystals; comparatively, a low supersaturation ratio favours larger crystal formation (Abbona et al 1985). Other factors, such as suspension density, particle size, and the presence of impurities, may also impact crystallisation and agglomeration (Bennet 2015)  Previous studies using the UBC-FBR indicated that, when a higher up flow velocity was used, struvite crystals grew larger and denser (Fattah 2004; Huang 2003). Hydrodynamics may be playing a role here in mass transport and mixing energy. Ohlinger et al (1999) found that higher mixing velocities reduced the time required for nucleation. There is an upper limit though, as higher up flow velocities will result in fine crystals being washed out of the reactor into the clarifier (which is undesirable). Velocities that are too high may also contribute to some particle breakup. A minimum velocity is required though to keep the reactor fluidized, and to promote mixing. The UBC FBR has 4 different diameter sizes as the flow travels up, resulting in increasing turbulence, or mixing, as velocity increases.  2.6 The UBC FBR   The UBC Fluidized Bed Reactor (FBR) was developed and tested through years of research at UBC. It has been designed to produce struvite pellets that are hard and about 1-2mm in diameter. Pellets are a desired end product, compared to fine crystals, because they have less surface area, enhancing the slow release of nutrients, and they are easier to harvest and dry. The typical UBC FBR set up is shown in Figure 3. It consists of a bottom feed injection and recycle area, four stages of increasing diameter, a clarifier to prevent fine crystals being recycled with recycle flows, and pH control. 8   CHAPTER 2: BACKGROUND   Figure 3: Typical UBC FBR set up (Bennet 2015) The flows begin in the bottom section of the reactor where the main feed enters and mixes with the recycle flows from the clarifier. Immediately after, all flows combine in the injector port, Figure 4. The injector port inputs, for caustic pH control and secondary feed, are designed to jet in and improve mixing in this area. Typically MgCl2 is added here to avoid unwanted precipitating in the main feed tank. In the current experiment, MgCl2 was initially added separately like this (Run 1 and 2), but when effluent was acidified and re-used (Run 3-7) this feed line consisted only of water, to promote mixing. The main feed was mixed in all experiments, accounting for the dilution from the secondary feed.  Figure 4 - UBC-FBR injection port design (Fattah 2004) 9   CHAPTER 2: BACKGROUND  As the flows travel further up the reactor column, the increase in diameter promotes turbulent mixing at those points. At the beginning of the active zone, a pH probe continually monitors the pH and sends caustic pumping signals via a pH controller. The desired build-up of fluidized pellets and crystals are also observed to increase the turbidity and mixing within the reactor.  Pellets can form in hours to days, becoming smooth and hard from crystal growth and abrasion (Bennet 2015). As the pellets increase in mass, they drop lower into the reactor. The lowest zone is where these final large pellets are harvested from.  2.6.1 NH4-struvite Various researchers have used the UBC FBR to develop phosphorus recovery techniques through NH4-struvite formation. Bennet (2015) reported on the various operating conditions used to successfully grow NH4-struvite pellets. This is presented in Table 4. Table 4 - operation and performance for UBC-FBR NH4-struvite crystallizer from pilot studies (Bennet 2015)  Operational Parameter Britton, 2002 Penticton digester supernatant Huang, 2003 Lulu & Annacis digester supernatant Fattah, 2004 Lulu dewatering centrate 1Supersaturation  ratio 1.1~2.2 1.1~1.9 1.0~1.9 2Mg:P molar ratio 1.0~16.9 1.3~3 1.1~30 Temperature  (\u00b0C) 16-25 10-20 15-29 Total reactor flow (L\/min) 2.4~10.2 3.1~4.8 8.3~23.1 3Recycle ratio 3.0~23 4.0~10.3 6~12 HRT (min) Not reported 3.6~9.4 4.0~9.5 4CRT (days) 12~47 8~20 Not reported 5Up flow velocity (cm\/min) ~281 238~541 200~400 (seeded) Effluent P-PO4 (mg\/L) 3.9~43.6 3~13.5 2~54 %PO4 removal 0~91 88~98 24~100 %NH4 removal 0~26 1~22 5~10 Pellet diameter (mm) 0.5~2.1 1.5~3.5 1.4~3.6 1. Cube root of the ratio of conditional solubility product of the solution leaving the injector to that of equilibrium (PS-reactor\/PS-eq)1\/3 2. Mg:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. The volume of the crystal bed divided by the volumetric rate of crystal harvest 5. Velocity of the total flow measured at the harvest zone  2.6.2 K-struvite Bennet (2015) was the first to attempt producing a K-struvite pellet using the UBC FBR. She used similar UBC FBR operating parameters (up flow velocity, recycle rate, supersaturation ratio, and temperature) that had been successful for NH4-struvite pallet production. She also used optimal K-struvite feed concentrations she had determined in earlier lab experiments and modelling. 10   CHAPTER 2: BACKGROUND  Due to issues with pumps losing their prime, delays in pH control and pH probe calibration, Bennet was unable to stabilize pH and the reactor. The first attempt to use the UBC FBR to pelletize K-struvite was unsuccessful, and remained largely untested. This current work is the second attempt at using the UBC FBR to pelletize K-struvite.  2.7 PHREEQC Modelling  Incorporated into the latest struvite research at UBC is the use of the PHREEQC software program. This software is distributed by the United States Geological Survey (USGS). PHREEQC is a computer program written in the C and C++ programming languages that is designed to perform a wide variety of aqueous geochemical calculations. PHREEQC implements several types of aqueous models. Using any of these aqueous models, PHREEQC has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and one-dimensional (1D) transport calculations with reversible and irreversible reactions, which include aqueous, mineral, gas, solid-solution, surface-complexation, and ion-exchange equilibria, and specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and pressure and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters within specified compositional uncertainty limits (Parkhurst and Appelo 2013). The program inputs, relative to this project, include temperature, pH, feed concentrations and a database developed to guide the geochemical calculation of the software. The program output that is of most interest is the saturation index. The saturation index (SI) is related to the supersaturation ratio by Equation 6 \ud835\udc46\ud835\udc46\ud835\udc58\ud835\udc58 =  (10\ud835\udc46\ud835\udc46\ud835\udc46\ud835\udc46)1 3\ufffd       Equation 6  2.8 UBC K-struvite Research Building Blocks  This research builds on the findings of Bennet (2015). The key findings of that paper, when reviewing other K-struvite synthesis experiments, were that the previous studies either had used initial feed solution concentrations that would not produce pure K-struvite precipitate, or that the molar ratio of potassium to phosphorus was less than 1. This latter feed resulted in higher percentages of potassium removal; however, potassium is normally found in higher concentrations than phosphorus in the agricultural waste streams of interest for this study. Bennet (2015) conducted 2 experiments synthesizing K-struvite. The first determined a new solubility product for K-struvite previously shown in table 3. The results showed that it was less soluble than previously reported and fits the Van\u2019t Hoff model. The new solubility product was used to update the PHREEQC program for calculating the supersaturation ratio of K-struvite and other potential compounds, when synthesizing K-struvite. The second experiment conducted by Bennet was to determine optimum supersaturation ratios to synthesize K-struvite. This involved a series of experiments focused on adjusting initial solution 11   CHAPTER 2: BACKGROUND  concentrations and reaction pH at a constant temperature of 25\u00b0C. A summary of these tests is shown in Table 5. Table 5 - Summary of experiment 2 parameters for K-struvite synthesis batch tests (Bennet 2015)   Experiment Mg:K:P molar ratio1 Initial solution concentration  pH Initial SK T (\u00b0C)  High concentration 2A  1:3:1 Mg 287 mM 10.5 3.7     25 2B K 750 mM 9.0 13.5 2C P 250 mM 7.5 4.29  Low concentration 2D  3:11:1 Mg 9 mM 10.5 3.64 2E K 33 mM 9.0 1.42 2F P 3 mM 7.5 0.435  Optimal concentration  2G  3.5:50:1 Mg K P 24   mM 357 mM 6.8  mM  8.0  1.60  The optimal concentration used was chosen to have phosphorus concentrations and Mg:P molar ratios similar to that of animal wastes. The pH was selected to be 8, to reduce the amount of caustic used. Using PHREEQC, Bennet determined that, to produce pure K-struvite over cattiite \u2013 the greatest competing compound, the molar ratio of K:P had to be 50:1, resulting in a supersaturation ratio of 1.6, as shown in Figure 5.  Figure 5 - Optimizing the K:P ratio for low concentration K-struvite synthesis at pH 8.0, [P-PO4] = 8 mM (Bennet 2015) Bennet\u2019s recommendations for future work included further UBC research in the areas of: seeding the UBC FBR when trying to produce K-struvite pellets, studying the impacts of nitrogen in solution on K-struvite production, and attempting to produce a full-complement fertilizer, containing both NH4-struvite and K-struvite.  12   CHAPTER 2: BACKGROUND  2.9 Conclusions  Reviewing the literature revealed some directions for further study.  1. Bennet\u2019s (2015) UBC K-struvite research findings and recommendations for future work were incorporated into this project.   2. Research into K-struvite synthesis appears to have been explored. Many of the previous synthesis studies did not use similar feed concentrations and supersaturation ratios that were used in this study, based on Bennet (2015). For example, Satoshi\u2019s (2013) experiments used a molar ratio of Mg:K:P of 0.5:3:1; Lin et al (2012) used 1:1:1; and Li et al (2015) used 3:1:3. This study will use a molar ratio closer to 3.5:50:1, and a different supersaturation ratio.   3. The molar ratio Bennet identified as optimal is not normally found in the waste streams of interest, that will potentially be used as feed in later studies and applications. Therefore, it was expected that nutrient supplementation and\/or pre-treatment of the waste would be required to achieve those molar ratios.  4. Pellet production of K-struvite in the UBC FBR through crystal growth and agglomeration was unproven. Other synthesis of K-struvite appears to only be in the area of producing fine crystals. Bennet (2015) used the operating parameters of successful NH4-struvite pellet production as a basis for designing initial tests in this area. This seemed logical and was followed for this study.  5. In comparing K-struvite to NH4-struvite, and attempting to duplicate UBC FBR conditions to produce a K-struvite pellet, notable differences in K-struvite were found or were lacking in further details. Crystal growth of K-struvite has largely been found to be needle-like, whereas crystal growth of NH4-struvite has been observed to range from needle-like to a more branched structure, which is usually targeted in the UBC FBR. Also, it is unknown what the difference in zeta potential (electrokinetic potential) is between the two types of struvite, and how this might impact the colloidal behavior of the particles.  13   CHAPTER 3: RESEARCH OBJECTIVES  The purpose of this research was to better understand conditions needed to pelletize K-struvite for future applications, removing and recovering phosphates and potassium from waste waters. Two experiments were conducted, gathering data with the purpose of better understanding these conditions: Experiment 1: 1. Determine the effects of nitrogen products (NH4, NO3, and NO2) on the formation of K-struvite. It is currently known the NH4 struvite forms preferentially over K-struvite, but not at what concentrations it would cease to govern. Further, if nitrites or nitrates were still present after nitrification, it was not known what impact these would have on K-struvite formation.  Experiment 2:  2. Assess the pellet production potential of pure K-struvite. Determine the effects of varying pH, operational recycling, and the feed P:K ratio on K-struvite in the UBC FBR.  3. Assess the pellet production potential of K-struvite intermittently switching to a NH4-struvite feed in the UBC FBR, thus creating a full-complement struvite pellet. The two experiments each have a chapter detailing the experiments and results. Each experiment had multiple runs to determine the effects of changing conditions. These objectives and experiments were based on a continuation of Bennet\u2019s (2015) UBC K-struvite research.  14   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF NITROGEN PRODUCTS ON K-STRUVITE FORMATION  4.1 Objectives  The objective of this experiment was to determine what impacts that varying concentrations of NH4, NO3, and NO2 ions might have on K-struvite formation. NH4-struvite is expected to form preferentially over K-struvite when NH4 ions are present at high concentrations. It was further hypothesized that NO3 and NO2 ions would have minimal impact on K-struvite formation.  4.2 Materials and Methods  Experiments were conducted to determine the effects of NH4, NO3, and NO2 ions on K-struvite formation. The experiment materials and methods were designed to be as similar as possible to Experiment 2 in Bennet\u2019s (2015) K-struvite synthesis experiments previously undertaken at UBC. 4.2.1 Materials and equipment 4.2.1.1 Batch Test method and apparatus Two 500mL flasks, were run in parallel. They were stirred, and kept in a temperature controlled 25\u00b0C bath. The flasks were rinsed with dilute HCl acid, and then distilled water, before beginning each run (Bennet 2015). Figure 6 shows the bench-scale setup.  Figure 6: Two 500mL flasks, run in parallel, stirred, and kept in a temperature controlled 25\u00b0C bath. Other associated monitoring tools, reagents, and sampling tools at the bench.15   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE  4.2.1.2 Reagents used Analytical grade chemicals were used for reagents. Distilled water was used to mix feed stocks and rinse equipment (Bennet 2015). 4.2.1.3 pH and Conductivity monitoring The pH was monitored using a single Oakton pH 11 Series meter with ATC. The meter was calibrated daily using pH 4, 7, and 10 buffer solutions. The conductivity was monitored using an Oakton CON 400 Series meter. The meter was calibrated daily using potassium chloride standards, similar in ionic strength to that expected in the solution (Bennet 2015). 4.2.1.4 Sample collection and preservation Sample collection syringes and storage tubes were cleaned and rinsed before use. Liquid samples were collected using a 50mL syringe, filtered through a 0.45um filter, and preserved using 1 drop of concentrated HCl. Solid samples were also collected with a 50mL syringe, filtered through a 0.45um vacuum filter, rinsed with distilled water and reagent methanol, left to dry in the ambient atmosphere, and then stored (Bennet 2015). 4.2.2 Analytical methods 4.2.2.1 Magnesium analysis Samples were analyzed for magnesium using a Varian Inc. SpectrAA220 Fast Sequential Atomic Absorption spectrophotometer. Samples were diluted to within the calibration range using distilled water and standards were prepared using MgCl2. A 100 g\/L lanthanum solution was prepared from reagent grade lanthanum nitrate, La(NO3)3 and distilled water to reduce background matrix interference. Prior to each set of analyses, fresh deionized water was provided for auto-sampler rinsing and the magnesium lamp was optimized and warmed up (Bennet 2015). 4.2.2.2 Phosphate analysis Samples were analyzed for phosphate by flow injection analysis using the Lachat QuikChem 8000 using Method 4500-NH3 H and 4500-P G from Standard Methods for the Examination of Water and Waste water (American Public Health Association, American Water Works Association, and Water Environment Federation 2012). Samples were prepared and diluted to within the calibration range with distilled water. Calibration standard solutions were composed of reagent grade potassium phosphate monobasic (KH2PO4) in distilled water (Bennet 2015). 4.2.2.3 Potassium analysis Samples were analyzed for potassium using the Varian SpectrAA 220 Fast Sequential Atomic Absorption Spectrophotometer. Samples were diluted to within the calibration range using distilled water and standards of 5, 10, 50, 100 and 500 mg\/L were prepared using KCl. A 5 g\/L Cs+ solution was prepared as an ionization suppressant. Prior to each set of analyses, fresh deionized water was provided for auto-sampler rinsing. The potassium lamp was optimized and warmed up before use (Bennet 2015). 16   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE  4.2.2.5 X-Ray diffraction analysis Solid samples were analyzed to confirm presence of crystalline phases using a Bruker D8 Advance X-ray diffractometer using CuK \u03b1radiation. X-ray diffraction (XRD) output peak patterns were identified using the powder diffraction database file, provided by the International Center for Diffraction Data. This instrument was located in the UBC Department of Chemistry (Bennet 2015). 4.2.3. Quality assurance & statistical methods Every tenth sample was analyzed in duplicate. Data points out of the calibration range, or which appeared to be contaminated were discarded. Experimental blanks were run during experiments and sample blanks were run during chemical analysis, to reduce contamination errors and to ensure the quality of the data. Averages and standard deviations were calculated for analyte concentrations in solid and liquid samples. The average and the standard deviation of the parallel reactors were reported as the result. 4.2.4 Experimental setup For each experiment, two parallel, bathed, stirred 500mL flasks were used, connected subsequently with a thermostat set at 25\u00b0C. 1M and 5M NaOH solutions were used to control pH. Before each experiment, the flasks and stirrers were cleaned with a brush, followed by a dilute hydrochloric acid rinse, tap water rinse, and distilled water rinse (Bennet 2015). 4.2.5 Experimental procedure 4.2.5.1 Optimal concentration Bennet (2015) used PHREEQC to determine that an optimal Mg:K:P ratio was approximately 3.5:50:1 for a specific waste water matrix. To begin with, a similar initial concentration and molar ratio was used. The initial Mg:K:P ratio was approximately 4:58:1 and SK was 1.5. Initial concentrations in the reactor were as follows: Mg  638 mg\/l   26.3 mM  K  13825 mg\/l   353.6 mM P-PO4  188 mg\/l   6.1 mM Control tests, to form pure K-struvite, were performed first. Subsequent tests added weighed solids of reagent NH4Cl, NaNO3, NaNO2, and NH4-struvite pellets, which were later used as seeds in the UBC FBR. The solids were added to the K and P mixture before Mg was added. Additive NH4 concentrations used were based on common NH4 concentrations found in most waste waters. The concentrations of NO2 and NO3 were selected to mimic concentrations if the NH4 was fully nitrified, prior to the waste water entering a K-struvite reactor for phosphorus removal.  This experiment was conducted at pH 8, 25\u00b0C and precipitate samples were taken at the following intervals: 1 hr (A1, B1), 3 hr (A2, B2), 9 hr (A3, B3) and 24 hr (A4, B4). Using a syringe, approximately 100 mL of sample was drawn and filtered at each interval. Select precipitate samples were then analyzed for K+, Mg2+ and P-PO43-, as well as by XRD analysis, as described in Section 4.2.2 (Bennet 2015). 17   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE  4.3 Results and Discussion  Table 6 shows a summary of the bench experiment data conducted to better understand K-struvite chemistry and the influence nitrogen-based additives might have. Detailed liquids chemical analysis and experimental conditions can be found in Appendix A. XRD scans, microscope photographs, and chemical analysis results of select solids samples are located in Appendix B. Table 6: Benchtop Experiment Additives Run Additive Additive Initial Concentration (N - mg\/L) XRD Analysis  None Control \u2013 No Additives K-struvite, Cattiite 1 N-NH4 13, 42, 79, 393, 785 NH4-struvite \u2013 at N of 785 mg\/L  2 N-NO2 19, 41, 122, 304, 609 K-struvite, Cattiite \u2013 at N of 609 mg\/L  3 N-NO3 5, 16, 49, 329, 824 K-struvite, Cattiite \u2013 at N of 824 mg\/L  4 NH4-struvite Seeds 100, 1000, 4000 mg seeds\/L    Control experiments to produce pure K-struvite, without nitrogen-based additives, and form a baseline value, were conducted at the beginning and end of the investigation. XRD scans and chemical analysis showed that trace amounts of cattiite were produced in these experiments. The crystals that were formed in this experiment all exhibited similar crystal structures. Figure 7 shows the typical fine, needle-like structures observed throughout this experiment.  18   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE   Figure 7 \u2013 Experiment 1, Control, Sample SL7A4 (10x), fine needle-like crystals  In the experiments where NO2 and NO3 additives were added, it was observed that there was little impact on the removal of phosphorus, with less than 9% difference from the control (Figure 8). It was also observed that there was little impact on the mass of precipitate produced, with the highest average difference being less than 14% from the control at the highest tested NO2 additive concentration (Figure 9). At the highest NO2 and NO3 additive concentrations, K-struvite was still being formed, as shown in the liquid and solids analyses respectively. Further testing with more data points and larger concentration ranges could be conducted in the future to determine if the highest NO2 data point is part of an upward trend in phosphorus removal and solids production.  It was observed that NH4 additives had the greatest impact on both phosphorus removal as well as K-struvite formation, in this experimental series. Average phosphorus removal was up to 21% higher, and average solids produced were up to 29% higher than the control averages.  It was found that the highest concentration of NH4 additive tested (785 mg\/L N-NH4) produced NH4-struvite, with only traces of K-struvite. Chemical analysis showed that potassium was dominant in the precipitate, up to about 5.6mM N-NH4 additive. This confirms the work of Satoshi et al (2013), that low concentrations of NH4 (<1.1mM) are required, if K-struvite is to be formed. The 5.6mM point found in this research could be considered a target NH4 concentration required to begin producing K-struvite over NH4-struvite, if a waste stream is being treated to later be used for K-struvite feed. 19   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE   Figure 8: Average % Phosphorus Removal in Experiment 1  Figure 9: Average Solids Produced In Experiment 1 Lastly, when NH4-struvite seeds were added, limited amounts of NH4 were detected in solution, phosphorus removal was increased only marginally, and solids produced were about equal to the control tests. These results are summarized and can be found in Appendix A. 70%75%80%85%90%95%100%0 200 400 600 800 1000Average P Removal[N] mg\/LNH4NO2NO3Control0.500.550.600.650.700.750.800 100 200 300 400 500 600 700 800 900Average Precipitate Mass Produced (g)[N] mg\/LNH4NO2NO3Control20   CHAPTER 4: EXPERIMENT 1 \u2013 EFFECTS OF N PRODUCTS ON K-STRUVITE  4.4 Conclusions  Experiments to produce pure K-struvite, without nitrogen-based additives to form a baseline, were conducted at the beginning and end of the investigation. While K-struvite was largely formed, small amounts of Cattiite were detected in the XRD scans and chemical analysis of the crystal samples, shown and summarized in Appendix A.  NH4 present in solution will form NH4-struvite preferentially and K-struvite will not be produced in any significant amount, when the NH4 concentration exceeds about 5.6mM. Since NO2 and NO3 additives had little impact the removal of phosphorus or the expected formation of solids, the more nitrified a waste water is that contains high concentrations of potassium, such as dairy manure, the more chemical preference for K-struvite formation is established due to reduction in NH4 concentration. When NH4-struvite seeds were added, limited amounts of NH4 were detected in solution, phosphorus removal was increased only marginally, and solids produced were about equal to the control tests. Therefore, it was not expected that seeding the UBC FBR in Experiment 2, with these NH4-struvite seeds, would greatly impact the production of K-struvite in the actual FBR reactor.  21   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.1 Objectives  The objective of this experiment was to assess the pellet production potential of K-struvite in the UBC FBR, using synthetic feed and NH4-struvite seed material. This was the second attempt to produce K-struvite pellets in the UBC FBR and follows research by Bennet (2015); due to mechanical issues, K-struvite was unable to be consistently produced. There were 7 different experimental runs, and Table 7 discusses the objectives of each. Table 7 \u2013 Experiment 2 Run Objectives Run Objective 1 \u2022 Familiarize the operator with reactor equipment and operation.  \u2022 Determine what pH is required to achieve a Sk target of 1.6.  \u2022 Collect general operating data. 2 \u2022 Target pH 8.1 to achieve an Sk of 1.6. \u2022 Multi-day run to assess pellet production potential.  \u2022 Use NH4-struvite Seeds. 3 \u2022 Test a range of pH\u2019s (6.5-8.0) to assess pellet production potential.  \u2022 Use NH4-struvite Seeds. 4 \u2022 Target pH 8 and 50:1 K:P ratio.  \u2022 Recycle without feed every other day to test operational impacts on sloughing and assess pellet production potential.  \u2022 Use NH4-struvite Seeds. 5 \u2022 Target pH 8 and 40:1 K:P ratio.  \u2022 Determine if K-struvite is produced at a lower K:P ratio and its impact on pellet production. \u2022 Recycle without feed every other day to test operational impacts on sloughing and assess pellet production potential.  \u2022 Use NH4-struvite Seeds. 6 \u2022 Target pH 8 and 30:1 K:P ratio.  \u2022 Determine if K-struvite is produced at a lower K:P ratio and its impact on pellet production. \u2022 Recycle without feed every other day to test operational impacts on sloughing and assess pellet production potential.  \u2022 Use NH4-struvite Seeds. 22   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  7 \u2022 Target pH 8 and alternate between a 50:1 K:P ratio K-struvite Feed and Traditional NH4-struvite Feed, to attempt layering the two types of struvite and assess pellet production potential.  \u2022 Use NH4-struvite Seeds.  5.2 Materials and Methods  Seven experimental runs were conducted to determine the effects of pH, operational recycling, reduced K:P ratios, and alternating NH4-struvite and K-struvite feed, on K-struvite formation. The experimental materials and methods were designed to be as similar as possible to Experiment 3 in Bennet\u2019s K-struvite synthesis experiments at UBC, which was based on proven successful operating parameters for NH4-struvite pellet production (Bennet 2015).  5.2.1 Materials and equipment 5.2.1.1 Reagents used Analytical grade chemicals were used for reagents. City water was used to mix feed stocks and distilled water was used to rinse equipment. 5.2.1.2 Reactor monitoring The reactor was monitored throughout each day of operation. Monitoring data was recorded twice a day, unless operation changed in a way that demanded more or less. Recorded monitoring data included flow, pH, temperature, conductivity, corresponding sample ID, and any visual observations. The pH and temperature monitoring was measured with an Oakton pH 11 Series meter with ATC. The instrument calibration was done daily with pH 4, 7, and 10 buffer solutions. The conductivity monitoring was done with an Oakton CON 400 Series meter. The instrument calibration was done daily with potassium chloride standards with ionic strength, similar to the strengths of the experimental solutions. 5.2.1.3 Sample collection and preservation The reactor was sampled once per day of operation, unless operations changed in a way that demanded more or less. Samples were taken at the end of each approximate 24 hour period, to ensure stabilization of the reactor had occurred if any operating parameters had been adjusted after the previous sampling event. Sample collection syringes and storage tubes were cleaned and rinsed before use. Liquid samples were collected using a 50mL syringe, once a day, from each of the sample points identified in Figure 10. Liquid samples were filtered through a 0.45um filter, and preserved using 1 drop of concentrated HCl. Chemical analyses of the liquid samples was performed for potassium, magnesium and phosphate using the analytical methods described in Section 4.2.2.  Solid samples were collected typically from the zone designated 2A in Figure 10, by slowly opening a sample port on the side of the reactor until a low flow of reactor liquid drained via tubing into a sample 23   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  bucket. This sample was then filtered through a 0.45um vacuum filter, rinsed with distilled water and reagent methanol, left to dry in the ambient atmosphere, and then stored.  5.2.2 Analytical methods Analytical methods used are similar to the methods outlined in Section 4.2.2. 5.2.3. Quality assurance & statistical methods Quality assurance and statistical methods are outlined in Section 4.2.3. 5.2.4 Experimental setup This experiment took the basic results obtained from Bennet (2015) as a starting point, and used similar methods and concentrations. The UBC pilot scale FBR was set up at the UBC Staging Environmental Research Centre (SERC) and was operated with an objective of maintaining steady state operation parameters in the FBR. To begin, the feed tanks, reactor, effluent tanks, and other associated equipment and tools were cleaned. Then critical equipment including: two \u2013 1500 L feed tanks, one 100 L feed tank, recycle pump, feed pumps, pH controller and pump, clarifier tank, sump tank and pump, and caustic feed tank were set up inside the heated SERC workshop for better temperature control during winter conditions. The reactor feed setup initially included the typical, separated, magnesium feed stream to improve injection port mixing (Run 1 and 2). Later, as effluent solution was re-used for feed, and magnesium was included in the main feed solution, this side stream then used only City water to ensure injection port mixing (Run 3 to 7). When magnesium was included in the main feed tank, pH was lowered to maintain under saturated conditions. The total volume of the UBC FBR is approximately 6.5 L; the basic set up is shown in Figure 10, with photos of the indoor set up in Figure 11. The pumps included 2 Masterflex feed pumps set at 0.2 L\/min for the main feed line and 0.02 L\/min for the injector port feed line. The recycle pump selected was a Moyno 500 pump, maintaining a flow of 1.8 L\/min. These combined flows created up flow velocities reaching approximately 400 cm\/min in the 1 inch diameter harvest zone section of the reactor, similar to that selected for NH4-struvite pellet production. To control pH, a pH probe in the active zone was connected to an Omega pH controller, controlling a BLX pump drawing from a 1-2M NaOH solution, and introduced at the injector port. Reactor temperature was controlled as much as possible through building temperature controls; however the uninsulated building temperature did fluctuate due to external temperatures, and therefore, so did the reactor temperature. The indoor temperature fluctuations however, were in the normal range that the reactor has been operated at historically, outdoors in summer months. 24   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 10: General Schematic of the UBC FBR     Figure 11: Indoor set-up of the UBC FBR 25   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Reactor maintenance included cleaning the injection port from precipitate buildup, draining fines from the clarifier, calibrating the in-reactor pH probe controlling the pH and monitoring it for drift, while in continuous flow operation. 5.3 Run 1  5.3.1 Run 1 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash as the main potassium source. The feed pH was about 5.6 and the magnesium was kept in a separate feed tank to prevent precipitation before feed entered the reactor. Feed was mixed to be able to run a 7 day experiment using these concentrations P 295 mg\/L 10 mmol\/L Mg 521 mg\/L 21 mmol\/L K 13739 mg\/L 351 mmol\/L Mg:K:P Ratio 2:37:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions.  5.3.2 Run 1 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. Reactor start-up consisted of filling the clarifier a quarter full of feed and a quarter full of water, to hasten continuous reactor stabilization. The reactor appeared to exhibit a stable pH and operation after about 8 hours. The daily samples were analyzed in the lab on the same day, to determine what operational adjustments were required to meet the target supersaturation ratio of 1.6. A summary of the operational parameters achieved is shown in Table 8. Further run information can be found in Appendix C and D.           26   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Table 8 - Run 1 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.6 1-1.4 Average 1.2 2Mg:K:P molar ratio 3:50:1 Mg:P 3.4 \u2013 6.4 K:P 84 \u2013 185 Average 5:131:1 Reactor pH 8 8.1 \u2013 8.5 Average 8.3 Temperature, \u00b0C 15-20 17-18 Average 17.5 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.3.3 Run 1 Results and Discussion The first run familiarized this operator with the equipment. Increasing the pH appeared to increase the visible activity of crystal growth inside the reactor (see Figure 12). A pH above about 8.2 would result in many fine crystals being produced and washing out of the top of the reactor, entering the clarifier. This was undesirable, since crystal growth should be targeted for in the reactor.  Liquid analysis showed an average 77% removal of phosphorus for this Run, and solids analysis of a sample taken at the end of the Run verified K-struvite was forming in reactor.  A lower Sk than expected was found. Based on the principles of this parameter discussed in the background section, the Sk could be increased by increasing the pH. However, by increasing the pH, more fine crystals would be produced, and the K:P ratio would be expected to also increase. The K:P ratio was already higher than expected and this ratio is likely why no competing compounds were found in solids analysis. Brown NH4-struvite seeds were added to the reactor three days into the run. White K-struvite crystals were observed to coat the brown seeds, but would slough off when harvested, leaving only a thin coating of white crystals (see Figure 13 &14). It was uncertain if this was due to not enough time in the reactor, the cohesion forces between the K-struvite and the seed material, the crystal structure of K-struvite succumbing to the shear forces during harvesting, or a combination of these factors. Figure 15 shows the harvested pellets from Run 1. 27   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Figure 12 \u2013 Run 1 Start-up, precipitates forming Figure 13 \u2013 Run 1, K-struvite forming around brown NH4-struvite seeds in active zone  Figure 14 \u2013 Run 1, K-struvite forming around brown NH4-struvite seeds in active zone Figure 15 \u2013 Run 1, harvested pellets (bottom), compared to brown NH4-struvite seeds (top) 28   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.4 Run 2  5.4.1 Run 2 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash as the main potassium source. The feed pH was about 5.4 and the magnesium was kept in a separate feed tank to prevent precipitation before feed entered the reactor. Feed was mixed to be able to run a 7 day experiment using these concentrations P 289 mg\/L 9 mmol\/L Mg 571 mg\/L 24 mmol\/L K 12959 mg\/L 331 mmol\/L Mg:K:P Ratio 3:36:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions.  5.4.2 Run 2 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. Reactor start-up consisted of keeping the clarifier full from Run 1, which had similar feed and operating parameters. The reactor exhibited a stable pH and operation within about 4 hours after start-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic K-struvite coated the seed material, as well as to expedite pellet production. A summary of the operational parameters achieved is shown in Table 9. Further run information can be found in Appendix C and D.  Table 9 - Run 2 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.6 1.2-1.3 Average 1.2 2Mg:K:P molar ratio 3:50:1 Mg:P 4.1 \u2013 5.2 K:P 87 \u2013 111 Average 4.7:100:1 Reactor pH 8.1 8.1 \u2013 8.2 Average 8.1 Temperature, \u00b0C 15-20 17.5-18.9 Average 18.4 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  29   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.4.3 Run 2 Results and Discussion The second run targeted a pH of 8.1. At this pH, Run 1 had shown fine crystals not being washed out of the reactor at this pH, and K-struvite had grown on the NH4-seeds. Running it for a week at this constant setting was designed to determine if, through crystal growth and\/or agglomeration, the newly formed K-struvite pellets would stay together when harvested. The reactor remained in a steady state throughout the run.  Liquid analyses showed an average 70% removal of phosphorus for this run; solids analysis of a sample taken at the end of the Run verified K-struvite was forming in reactor. White K-struvite crystals were observed to coat the brown seeds, roughly doubling the 0.5 mm seeds in diameter after 3 days, but would slough off when harvested, leaving only a thin coating of white crystals. This characteristic did not change throughout the run and no observed improvement to the pellet\u2019s resistance to shear force was observed at the end of the run. Pellet diameter in the reactor was observed to grow in size for about 3 days. After that period, growth did not appear to progress as rapidly.  Figures 16-20 depict various observations photographed during this run. Figure 16 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone Figure 17 - Run 2, K-struvite forming around brown NH4-struvite seeds in Fine zone. Colour difference noticeable from seeds that have settled on the lip at the bottom of the Fine zone.  30   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 18 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone  Figure 19 \u2013 Run 2, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)   Figure 20 - Run 2, K-struvite forming around brown NH4-struvite seeds in active zone 31   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  After a week of operating this run, the pH was adjusted to 9.0 for a 24 hour period, to observe what impact a high pH would have. It resulted in a Mg:K:P molar ratio at the injector of 11:285:1, 97% removal of phosphorus, and an Sk of 1.1. There were no observed improvements to the solids when harvested. The amount of fine crystals produced increased significantly, with many fines building up in the clarifier. This last day of operation clearly showed the large impact pH can have on the molar ratio.  5.5 Run 3  5.5.1 Run 3 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash, as the main potassium source. Run 1 and 2 utilized a batch of feed that was mixed to last two weeks. For this run, that effluent was reused after being acidified and then topped up with chemicals to the desired feed concentrations. The pH was about 3.6 to prevent precipitation before feed entered the reactor. The previously used magnesium feed tank and injector line was left in operation, using city water, after washing out the feed tank. Feed was mixed to be able to run a 7 day experiment using these concentrations P 241 mg\/L 8 mmol\/L Mg 484 mg\/L 20 mmol\/L K 12008 mg\/L 307 mmol\/L Mg:K:P Ratio 3:39:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions.  5.5.2 Run 3 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. At the end of the 7 days, the reactor feed was turned off and the recycle was left to run for 3 days. Reactor start-up consisted of keeping the clarifier full from Run 2, which had similar feed and operating parameters. The reactor exhibited a stable pH and operation within about 4 hours after start-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic K-struvite coated the seed material, as well as to expedite pellet production.  A range of pH was targeted to collect a wide range of data and to determine if lower Sk would result in crystal growth more suitable for pellet production, that could sustain the forces of harvest. A summary of the operational parameters achieved is shown in Table 10. Further run information can be found in Appendix C and D.    32   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Table 10 - Run 3 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.0-1.6 0.5-1.2 Average 0.95 2Mg:K:P molar ratio 3:50:1 Mg:P 2.4 \u2013 3.7 K:P 38 \u2013 69 Average 3:54:1 Reactor pH na 6.6 \u2013 7.9 Average 7.4 Temperature, \u00b0C 15-20 15-19 Average 16.4 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.5.3 Run 3 Results and Discussion The third run targeted a range of pH\u2019s (6.5, 7.0, 7.5 and 8.0). The first three days operated at pH\u2019s below pH 7.5; NH4-struvite seeds dissolved in solution; nothing visibly formed and the Sk was less than 1.0. At a pH of 7.5, no noticeable dissolving of seeds or crystal growth occurred, and the Sk was 1.0, a point of equilibrium. At a pH of 7.9, K-struvite was forming and the Sk was approximately 1.2. It was apparent, that, to achieve a target supersaturation ratio with a fixed feed concentration and temperature, the best way to adjust Sk was to adjust the pH. Figure 21 shows the relationship between pH and Sk in this run.   Figure 21 \u2013 Reactor pH influence on solution supersaturation ratio (Sk) Liquid analyses showed an average 41% removal of phosphorus for this run, due to low pH. Solids analysis of a sample taken at the end of the run verified K-struvite was forming in the reactor. When pH was at 7.9, white K-struvite crystals were observed to coat the brown seeds, but would slough off when harvested, leaving only a thin coating of white crystals. Figure 22 shows the relationship between 00.20.40.60.811.21.46 6.5 7 7.5 8 8.5S kpH33   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  phosphorus removal and pH after the first three runs. While not fitting a linear trend, increases in pH led to an increase in phosphorus removal. Increasing the pH, therefore, has the potential to largely affect the reported molar ratios to phosphorus, as well.   Figure 22 \u2013 pH impact on phosphorus removal in the UBC FBR, Runs 1-3 At the end of Run 3, a 3 day recycle was started where the feed was turned off and only the recycle was left on. It was reported earlier that some NH4-struvite experiment runs at UBC had operated recycle runs like this on weekends, while the student operators took breaks. It was unreported what effect this might have, other than extending time for agglomeration to occur. The harvested solids at the end of this recycle run may have shown improved resistance to sloughing, but this was not measured.  Figures 23-25 show photographs taken during this particular Run. Especially noticeable are the colour differences in pellets formed, shown in Figure 25. 0%10%20%30%40%50%60%70%80%90%100%7.0 7.5 8.0 8.5 9.0 9.5P RemovalpHRun 1 - 334   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 23 - Run 3, K-struvite forming around brown NH4-struvite seeds in active zone  Figure 24 \u2013 Run 2, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)   Figure 25 - Run 3, K-struvite forming around brown NH4-struvite seeds in Fine zone. Colour difference noticeable from seeds that have settled on the lip at the bottom of the Fine zone. 35   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.6 Run 4  5.6.1 Run 4 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash, as the main potassium source. Run 1 and 2 utilized a batch of feed that was mixed to last two weeks. For this run, that effluent was reused after being acidified and then topped up with chemicals to the desired feed concentrations. The pH was about 3.6 to prevent precipitation before feed entered the reactor. The previously used magnesium feed tank and injector line was left in operation, using city water, after washing out the feed tank. Feed was mixed to be able to run a 7 day experiment using these concentrations P 386 mg\/L 12 mmol\/L Mg 695 mg\/L 29 mmol\/L K 11920 mg\/L 305 mmol\/L Mg:K:P Ratio 2:24:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions.  5.6.2 Run 4 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic K-struvite coated the seed material, as well as expedite pellet production. Due to Run 3 having inconclusive results regarding the effects of recycling, every other day in this run, the feed would be turned off and it would be left to recycle. Reactor start-up consisted of keeping the clarifier full from Run 3, which had similar feed and operating parameters. The reactor exhibited a stable pH and operation, within about 4 hours after start-up. A summary of the operational parameters achieved is shown in Table 11. Further run information can be found in Appendix C and D.          36   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Table 11 - Run 4 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.6 1.5-1.6 Average 1.6 2Mg:K:P molar ratio 3:50:1 Mg:P 5.6 \u2013 5.8 K:P 65 \u2013 71 Average 6:69:1 Reactor pH 8 7.9 \u2013 8.0 Average 8.0 Temperature, \u00b0C 15-20 16-20 Average 17.9 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.6.3 Run 4 Results and Discussion Pellet growth was similar to Run 2, where white K-struvite crystals were observed to coat the brown seeds, roughly doubling the 0.5 mm seeds in diameter, but would slough off when harvested, leaving only a thin coating of white crystals. The solids harvested every day did not show a measurable or significant improvement to resistance in sloughing, after the reactor was left on recycle during the previous 24 hour period. Liquid analyses showed an average 71% removal of phosphorus for this run, and solids analysis of a sample taken at the end of the run verified K-struvite was forming in reactor (see Figure 26 for size and colour of pellets formed).  37   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 26 \u2013 Run 4, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)  5.7 Run 5  5.7.1 Run 5 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash, as the main potassium source. For this run, effluent from Run 3 was reused after being diluted, acidified and then topped up with chemicals to the desired feed concentrations. The pH was about 6.1 to prevent precipitation before feed entered the reactor. The previously used magnesium feed tank and injector line was left in operation, using city water, after washing out the feed tank. Feed was mixed to be able to run a 7 day experiment using these concentrations P 365 mg\/L 12 mmol\/L Mg 685 mg\/L 28 mmol\/L K 9110 mg\/L 233 mmol\/L Mg:K:P Ratio 2:20:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions.  38   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.7.2 Run 5 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic K-struvite coated the seed material, as well as expedite pellet production. Due to Run 3 having inconclusive results regarding the effects of recycling, every other day in this run, the feed would be turned off and it would be left to recycle. Further, the K:P ratio was lowered, to target 40:1, to determine if K-struvite would still be produced, what effect this ratio might have on pellet production and what impacts any potential impurities might have. Reactor start-up consisted of keeping the clarifier full from Run 4, which had similar feed and operating parameters. The reactor exhibited a stable pH and operation within about 4 hours after start-up. A summary of the operational parameters achieved is shown in Table 12. Further run information can be found in Appendix C and D. Table 12 - Run 5 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.6 1.4-1.6 Average 1.5 2Mg:K:P molar ratio 3:40:1 Mg:P 4.5 \u2013 6.1 K:P 43 \u2013 59 Average 5:52:1 Reactor pH 8 8.0 \u2013 8.1 Average 8.1 Temperature, \u00b0C 15-20 15-18 Average 16.8 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.7.3 Run 5 Results and Discussion Pellet growth was similar to Run 4, where white K-struvite crystals were observed to coat the brown seeds, roughly doubling the 0.5 mm seeds in diameter, but would slough off when harvested, leaving only a thin coating of white crystals. The solids harvested every day did not show a measurable or significant improvement to resistance in sloughing, after the reactor was left on recycle during the previous 24 hour period.  Liquid analyses showed an average 66% removal of phosphorus for this run, and solids analysis of a sample taken at the end of the run verified K-struvite was forming in reactor.  Figures 27 and 27 show colour and quality of the pellets formed, as well as in-situ formation in the active zone. 39   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 27 \u2013 Run 5, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)  Figure 28 - Run 5, K-struvite forming around brown NH4-struvite seeds in active zone  5.8 Run 6  5.8.1 Run 6 Synthetic Feed Composition Synthetic feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash, as the main potassium source. For this run, effluent from Run 3 was reused after being diluted, acidified and then topped up with chemicals to the desired feed concentrations. The pH was about 5.9 to prevent precipitation before feed entered the reactor. The previously used magnesium feed tank and injector line was left in operation, using city water, after washing out the feed tank. Feed was mixed to be able to run a 7 day experiment using these concentrations P 383 mg\/L 12 mmol\/L Mg 539 mg\/L 22 mmol\/L K 7273 mg\/L 186 mmol\/L Mg:K:P Ratio 2:15:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions. 40   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.8.2 Run 6 Reactor Operation The reactor was operated for 7 days during this run, with recycle as described in the experimental set-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic K-struvite coats the seed material, as well as to expedite pellet production. Due to Run 3 having inconclusive results regarding the effects of recycling, every other day in this run, the feed would be turned off and it would be left to recycle. Further, the K:P ratio was lowered, to target 30:1, to determine if K-struvite would still be produced, what effect this ratio might have on pellet production and what impacts any potential impurities might have. Reactor start-up consisted of keeping the clarifier full from Run 5, which had similar feed and operating parameters. The reactor exhibited a stable pH and operation within about 4 hours after start-up. A summary of the operational parameters achieved is shown in Table 13. Further run information can be found in Appendix C and D. Table 13 \u2013 Run 6 average operating parameters Operational parameters Desired range Range achieved 1Supersaturation ratio in reactor 1.6 1.5-1.5 Average 1.5 2Mg:K:P molar ratio 3:30:1 Mg:P 2.8 \u2013 3.8 K:P 35 \u2013 42 Average 3:38:1 Reactor pH 8 8.1 \u2013 8.1 Average 8.1 Temperature, \u00b0C 15-20 18-19 Average 18.3 Total reactor flow (L\/min) 2 2 3Recycle ratio 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.8.3 Run 6 Results and Discussion Pellet growth was similar to Run 2, 3 (parts), 4 and 5, where white K-struvite crystals were observed to coat the brown seeds, roughly doubling the 0.5 mm seeds in diameter, but would slough off when harvested, leaving only a thin coating of white crystals. The solids harvested every day did not show a measurable or significant improvement to resistance in sloughing, after the reactor was left on recycle during the previous 24 hour period. Liquid analyses showed an average 67% removal of phosphorus for this run, and solids analysis of a sample taken at the end of the run verified K-struvite was forming in reactor.  Figures 29 and 30 show colour and quality of pellets formed, as well as struvite formation in-situ. 41   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 29 \u2013 Run 6, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)  Figure 30 - Run 6, K-struvite forming around brown NH4-struvite seeds in active zone  5.9 Run 7  5.9.1 Run 7 Synthetic Feed Composition Synthetic K-struvite feed was mixed using magnesium chloride as the magnesium source, monopotassium phosphate as a phosphorus source and muriate of potash, as the main potassium source. For this run, effluent from Run 4 was reused after being diluted, acidified and then topped up with chemicals to the desired feed concentrations. The pH was about 4.9 to prevent precipitation before feed entered the reactor. Synthetic NH4-struvite feed was freshly mixed using magnesium chloride as the magnesium source, monoammonium phosphate as a phosphorus source and ammonium chloride, as the main ammonium source. The pH was about 3.5 to prevent precipitation before feed entered the reactor. The previously used magnesium feed tank and injector line was left in operation, using city water, after washing out the feed tank. Feed was mixed to be able to run a 7 day experiment using these concentrations:    42   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  K-struvite Feed     NH4-struvite Feed P 459 mg\/L 15 mmol\/L  P 154 mg\/L 5 mmol\/L Mg 637 mg\/L 26 mmol\/L  Mg 236 mg\/L 10 mmol\/L K 13625 mg\/L 348 mmol\/L  N-NH4 736 mg\/L 53 mmol\/L Mg:K:P Ratio 2:24:1    Mg:NH4:P Ratio 2:11:1 *Feed concentrations are adjusted based on flows from main feed and secondary feed as described in the experimental set-up and observed conditions. 5.9.2 Run 7 Reactor Operation The reactor was operated for 7 days during this run using synthetic feed with recycle, as described in the experimental set-up. The reactor was seeded with brown NH4-struvite seeds, so it could be observed if the white synthetic struvite coated the seed material, as well as to expedite pellet production. Due to Runs 1-6 producing pellets that would not hold together under the force of harvesting, the purpose of Run 7 was to produce K-struvite every other day, and produce NH4-struvite the days between those. The NH4-struvite was \u201chypothesized\u201d to layer over the K-struvite and hold the pellet together under harvesting forces. NH4-struvite operating conditions, that were used to develop the K-struvite operation, were maintained for NH4-struvite operation. Reactor start-up consisted of keeping the clarifier full from Run 6, which had similar K-struvite feed and operating parameters. The reactor exhibited a stable pH and operation within about 4 hours after start-up. The next day, about half of the clarifier was emptied and stored (K-struvite effluent), it was then topped up to the \u00be level with NH4-struvite feed, to hasten the transition in reactor operation. The reactor exhibited a stable pH and operation within about 8 hours after switching. The next day, about half of the clarifier was emptied and stored (NH4-struvite effluent), it was topped up to full with previously stored K-struvite effluent, to hasten the transition again in reactor operation. The reactor exhibited a stable pH and operation within about 6 hours after switching. This operational switching happened each day and took about 6 hours for the reactor to stabilize each time. A summary of the operational parameters achieved is shown in Table 14. Further run information can be found in Appendix C and D.         43   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  Table 14 \u2013 Run 7 average operating parameters Operational parameters Desired range Range achieved K-struvite Range achieved NH4-struvite 1Supersaturation ratio in reactor 1.6 1.3-1.6 Average 1.5 1-1.3 Average 1.2 2Mg:K:P molar ratio 3:50:1 Mg:P 3.7 \u2013 4.0 K:P 127 \u2013 147 Average 4:134:1 Mg:P 3.8 \u2013 4.2 N:P 41 \u2013 45 Average 4:43:1 Reactor pH 8 8.0 \u2013 8.2 Average 8.1 8.0 \u2013 8.2 Average 8.1 Temperature, \u00b0C 15-20 13-14 Average 13.9 11-17 Average 13.8 Total reactor flow (L\/min) 2 2 2 3Recycle ratio 8.2 8.2 8.2 1. Modelled SI output from PHREEQC, converted into Sk using Equation 6 2. Mg:K:P molar ratio of the solution leaving the injector 3. Recycle flow divided by the influent feed flow 4. Velocity of the total flow measured at the harvest zone  5.9.3 Run 7 Results and Discussion The seventh run targeted a pH of 8.1, and the original K:P ratio. The purpose of Run 7 was to produce K-struvite every other day, and produce NH4-struvite the days in between. The NH4-struvite was anticipated to layer over the K-struvite and hold the pellet together while harvesting.  Liquid analyses showed an average 86% removal of phosphorus during K-struvite feed operation, and an average 100% removal of phosphorus during NH4-struvite feed operation for this run. Solids analysis of a sample taken at the end of the run verified the presence of K-struvite (about 23%) and NH4-struvite (about 77%) forming in the reactor. The high phosphorus removal observed during the NH4-struvite synthesis made the molar ratio reported in Table 14 seem higher than what was actually required.  White struvite crystals of both kinds were observed to coat the brown seeds. It was observed, but not investigated, that NH4-struvite run days appeared to create more growth in pellet size in the reactor, than during K-struvite run days. As anticipated, there were significant improvements to the pellet\u2019s resistance to shear force during harvest, even withstanding sieve forces. This was an \u201cin-situ\u201d breakthrough in reactor operation and targeted pellet quality. About 1mm pellets were grown. The pellets were not characteristically hard and smooth, but it is anticipated that changes to reactor operations and optimization, such as flow could change this. Figures 31-33 depict photographs taken during different stages of Run 7. 44   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 31 \u2013 Run 7, harvested pellets (bottom), compared to brown NH4-struvite seeds (top)   Figure 32 - Run 7, K-struvite forming around brown NH4-struvite seeds in active zone   Figure 33 \u2013 Run 7, harvested and sieved pellets (1mm, 0.5mm, and <0.5mm)   45   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR  5.10 Struvite crystal morphology  K-struvite was formed in runs 1 to 6. Photographs of crystal structure in selected, solids analysis samples can be found in Appendix D.  Inspecting the samples from these runs, crystal structure generally appeared to be lengthy, linear crystals, that appear to be fractured into smaller pieces after harvest. There was no apparent evidence of branching that Abbona and Boistelle (1979) found in NH4-struvite production. Figure 34 shows the typical crystal structure found in Runs 1 to 6.  Figure 34 \u2013 Run 2, Sample SL14_2A (10x) \u2013 K-struvite Both K-struvite and NH4-struvite were formed in run 7. Visual inspection of the crystal structure from solids formed in this run generally showed crystals that appeared to be large and branching. Figure 35 shows the typical crystal structure found in Run 7. 46   CHAPTER 5: EXPERIMENT 2 \u2013 K-STRUVITE IN THE UBC FBR   Figure 35 \u2013 Run 7, sample SL50_2A (10x) \u2013 NH4-struvite and K-struvite  5.11 Conclusions  K-struvite was produced in the reactor and formed around seed material; however it did not continuously \u201cstay together\u201d in pellet form, during harvesting except in Run 7. Therefore, the objective of forming a pure K-struvite pellet surrounding a seed remains an operational challenge for this FBR design. However, K-struvite can successfully be incorporated into a harvestable pellet using NH4-struvite as a binding crystal, thereby creating a full-complement, slow release, NPK fertilizer. Overall, the reactor operation to produce K-struvite is similar to the operation to produce NH4-struvite. Increasing the pH will increase the Sk , decreasing the temperature will increase the Sk, and increasing the Sk will lead to more fine crystals being produced. Further increasing the pH will increase the removal of phosphorus, but will have a large impact on the K:P ratio in the reactor. K-struvite was formed successfully at lower K:P ratio\u2019s than expected in the UBC FBR.  47   CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS  The purpose of this research was to further understand some of the basic chemistry involved in K-struvite formation and to attempt to form a K-struvite pellet in the UBC Fluidized Bed Reactor (FBR). It was evident that ammonia would impact K-struvite formation if present at elevated levels, while residual nitrified products would not. During this experiment, a pure K-struvite, harvestable pellet was unable to be produced consistently; however, layering K-struvite and NH4 struvite successfully produced a harvestable pellet.  6.1 Conclusions  The conclusions derived from this research, based on the objectives are: 1. Impacts of NH4, NO3, and NO2 on K-struvite Formation:  Ammonia was found to impact K-struvite production at a concentration of approximately 5.6mM, while NO3 and NO2 had little impact on K-struvite production at concentrations that might be found in fully nitrified animal waste water. Therefore, if using animal waste as a feed source, nitrification is recommended as a pre-treatment step, before using it to produce K-struvite.  2. Impacts of varying Sk on pellet production potential of K-struvite in the UBC FBR: Increasing the K-struvite supersaturation ratio, Sk, in the reactor caused a noticeable increase in the amount of fine crystals being produced. The primary method of increasing the Sk was to increase the pH. This also increased the removal of phosphorus, leading to an even greater K:P ratio in the reactor. 3. Impacts of varying operational recycle on pellet production potential of K-struvite in the UBC FBR: No significant improvements to the in-reactor, pellet structure was observed. Upon harvesting, in-reactor pellets still sloughed off the K-struvite that had formed around the seed material. This may suggest that agglomeration may not play as large a role as crystal growth, in pellet formation in the UBC FBR. 4. Impacts of varying K struvite feed K:P ratios on pellet production potential of K-struvite in the UBC FBR: Due to pH control, lowering the K:P ratio was explored only to a ratio of 38:1, instead of 30:1. Sample analysis still showed that pure K-struvite was being produced in the reactor at this ratio. Therefore, it is believed that lower K:P ratios may be suitable for producing K-struvite; this would reduce the amount of pre-treatment required to lower phosphorus, or the amount of nutrient addition, to increase potassium levels.48   CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS 5. Impacts of varying NH4 and K struvite feed on pellet production potential of K-struvite in the UBC FBR:   While a pure K-struvite pellet, coating a seed, was unable to be successfully produced, layering the K-struvite pellet in the reactor with NH4-struvite produced a pellet with both types of struvite, resistant to the forces of harvesting and sieving. While the first objective of forming a pure K-struvite pellet remains elusive, the second objective of forming a full-complement fertilizer pellet was answered. This method may be used to create such a blended product at commercial scale.  In considering the method of forming a full-complement, fertilizer pellet, this research suggests that this could be done in a series of steps when using one feed source. If using dairy waste for example, pre-treatment would be required to lower phosphorus to create a more desirable K:P ratio, while excess NH4 must be removed, when producing K-struvite.   6.2 Recommendations for Future Work  The observations and conclusions of this research lead to the following recommendations for future research at UBC to succeed this study:  1. Further bench K-struvite research similar to Experiment 1 may expand the field of knowledge of the basic K-struvite chemistry and crystal growth characteristics. This may include: a. Experiments with more data points focusing on ammonia influence and phosphorus sharing between the two types of struvite, to optimize the required amount of nitrification necessary, avoiding interference. b. Experiments testing the reduction of the K:P ratio to determine a lower limit and to understand the production of potential impurities, such as cattiite. c. Zeta potential tests to better characterize the crystal properties of K-struvite. Bennet (2015) observed that this research has not been done yet and current research at UBC may indicate that this may be an important factor to consider, when characterizing crystal and pellet growth.  2. Further UBC FBR based research is still required to investigate the potential to produce a pure K-struvite pellet. This research was unable to produce a pure K-struvite pellet that could withstand harvesting forces. However, a comprehensive investigation into this was not conducted with many operating parameters remaining unexplored. Bennet (2015) discusses the finding that varying magnesium ratios, varying flow rates, and extending growth times may impact the pellet size and hardness, in addition to the parameters that were explored in this experiment.  3. Further UBC FBR research is needed to optimize the successful NH4\/K-struvite pellet. Observations and findings from this experiment suggest that the process to produce a full-complement, struvite pellet may be optimized to produce a more desirable mix of struvite types. The following optimizing work is recommended: 49   CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS a. Set up the UBC FBR with a second clarifier, so that each type of feed has their own that can be switched to, when switching feeds. This will reduce reactor lag times, balancing chemical concentrations. b. Optimize the amount of time between switching feed. This may include exploring the crystal growth rates of NH4-struvite and K-struvite, and determining how much NH4-struvite growth is required to coat the K-struvite layer and still remain resistant to harvest forces. c. Explore the pellet size this process is able to produce, by extending growing times. d. Optimizing chemical concentrations in the reactor by incorporating the results from Recommendation 1. e. Optimize phosphorus removal through exploration of recycle ratio. Bench test data in this research points to improved phosphorus removal, with extended hydraulic retention time. f. Once more data is available relating to the functioning of the UBC FBR under K-struvite production, creating a model for K-struvite FBR outputs, to help operators predict crystal formation and effluent concentrations based on feed concentrations, pH, temperature and reactor flows, would be useful.  g. 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Zhang, Hui. 2013. \u201cPilot Scale Application of Microwave Technology for Dairy Manure Treatment and Nutrient Recovery through Struvite Crystallization.\u201d University of British Columbia.   57    APPENDIX A \u2013 Experiment 1: Benchtop Chemistry Experiment Data Table A1 \u2013 Experiment 1 Monitoring Data and Results      Final 24 h Average Concentrations (mg\/L)  Average Removal (%)     Run Additive Experiment 1 ID Date Additive Initial Concentration (N - mg\/L) N P K Mg N P K Mg XRD Analysis Temperature (\u00b0C) pH Conductivity (mS) Control None SL7 07-Aug-17 0   41 10735 483   78% 22% 24% K-struvite, Cattiite 25.0 \u00b1 0.1 8.0 \u00b1 0.1 38.6 SL27 27-Aug-17   38 8875 507   80% 36% 21% K-struvite, Cattiite 40.2 SL28 28-Aug-17   33 9267 502   83% 33% 21%   40.8 1 N-NH4 SL8 08-Aug-17 13 nd 30 10592 484  84% 23% 24%   25.0 \u00b1 0.3 8.0 \u00b1 0.1 36.5 SL9 09-Aug-17 42 33 22 10939 481 21% 88% 21% 25%   37.2 SL10 10-Aug-17 79 64 25 10590 480 18% 87% 23% 25%   36.3 SL11 11-Aug-17 393 291 8 10988 469 26% 96% 21% 26%   41.3 SL12 12-Aug-17 785 692 6 11186 458 12% 97% 19% 28% NH4-Struvite 43.6 2 N-NO2 SL13 13-Aug-17 19 21 35 11660 492 -8% 81% 16% 23%   25.0 \u00b1 0.1 8.0 \u00b1 0.1 38.7 SL14 14-Aug-17 41 43 36 11401 499 -6% 81% 18% 22%   38.6 SL15 15-Aug-17 122 129 40 11180 510 -6% 79% 19% 20%   40.2 SL16 16-Aug-17 304 283 36 11179 515 7% 81% 19% 19%   40.6 SL17 17-Aug-17 609 607 25 11446 500 0% 87% 17% 22% K-struvite, Cattiite 42.2 3 N-NO3 SL18 18-Aug-17 5 6 36 11139 524 -21% 81% 19% 18%   25.0 \u00b1 0.1 8.0 \u00b1 0.1 40.2 SL19 19-Aug-17 16 19 33 11486 499 -15% 82% 17% 22%   40.3 SL20 20-Aug-17 49 55 41 11455 516 -4% 78% 17% 19%   40.4 SL21 21-Aug-17 329 319 45 11759 502 10% 76% 15% 21%   40.8 SL22 22-Aug-17 824 873 39 11633 514 1% 79% 16% 19% K-struvite, Cattiite 43.4 4 NH4-struvite Seeds SL24 24-Aug-17 100mg\/L 16 29 10709 503 - 85% 23% 21%   25.0 \u00b1 0.1 8.0 \u00b1 0.1 39.8 SL25 25-Aug-17 1000mg\/L 29 21 10564 495 - 89% 24% 22%   39.5 SL26 26-Aug-17 4000mg\/L 43 27 8799 496 - 86% 36% 22%   40.5  58       APPENDIX B \u2013 Experiment 1: Benchtop Chemistry Experiment Solids Analysis  Table B1 \u2013 Experiment 1 Solids Analysis Data and Results  Run Additive Experiment 1 ID P (mM) Mg (mM) K (mM) N (mM) XRD Analysis Control None SL7A4 3.5 3.9 2.7  K-struvite, Cattiite SL27A4 3.8 4.0 2.9  K-struvite, Cattiite 1 NH4 SL8A4 4.3 4.2 2.8 0.6 - SL9A4 4.0 4.1 2.3 0.8 - SL10A4 3.9 4.1 1.9 1.1 - SL11A4 4.7 4.3 1.2 1.8 - SL12A4 5.3 4.4 0.8 2.5 NH4-struvite 2 NO2 SL17A4 4.2 4.1 3.1  K-struvite, Cattiite 3 NO3 SL22A4 3.7 4.0 2.9  K-struvite, Cattiite K-struvite and NH4-struvite have 1:1:1 molar ratios. Measurement errors and impurities such as Cattiite (Mg3(PO4)2:22H2O) may explain why the molar concentration of potassium of ammonia are not equal to that of phosphorus and magnesium.  Figure B1: Solids Molar Ratio of K and N-NH4 to P in Run 1, Experiment 10.000.100.200.300.400.500.600.700.800.901.000 10 20 30 40 50 60Molar Ratio to PN-NH4 Added (mM)K Molar RatioNH4 Molar Ratio59       APPENDIX B  Figure B2 \u2013 Experiment 1, Run 1, Sample SL7A4 (10x) \u2013 K-struvite and Cattiite XRD  Figure B3 \u2013 Experiment 1, Run 1, Sample SL12A4 (10x) \u2013 NH4-Struvite XRD  SL7A400-055-0828 (I) - Cattiite - Mg3(PO4)2\u00b722H2O - WL: 1.5406 - Triclinic - a 6.93200 - b 6.92500 - c 16.15400 - alpha 82.210 - beta 89.700 - gamma 119.510 - Primitive - P-1 (2) - 1 - 666.295 - F30= 16(0.000-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL7A4.raw - Start: 5.000 \u00b0 - End: 89.999 \u00b0 - Step: 0.019 \u00b0 - Step time: 48. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 10\/Lin (Cps)01002003004005002-Theta - Scale6 10 20 30 40 50 60SL12A401-077-2303 (*) - Struvite, syn - MgNH4PO4(H2O)6 - WL: 1.5406 - Orthorhombic - a 6.95500 - b 6.14200 - c 11.21800 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pmn21 (31) - 2 - 479.20File: SL12A4.raw - Start: 5.000 \u00b0 - End: 89.999 \u00b0 - Step: 0.019 \u00b0 - Step time: 48. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 10Lin (Cps)01002003004005006007008009002-Theta - Scale6 10 20 30 40 50 60 760       APPENDIX B  Figure B4 \u2013 Experiment 1, Run 2, Sample SL17A4 (10x) \u2013 K-struvite and Cattiite XRD   Figure B5 \u2013 Experiment 1, Run 3, Sample SL22A4 (10x) \u2013 K-struvite and Cattiite XRD  SL17A400-055-0828 (I) - Cattiite - Mg3(PO4)2\u00b722H2O - WL: 1.5406 - Triclinic - a 6.93200 - b 6.92500 - c 16.15400 - alpha 82.210 - beta 89.700 - gamma 119.510 - Primitive - P-1 (2) - 1 - 666.295 - F30= 16(0.000-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL17A4.raw - Start: 5.000 \u00b0 - End: 89.999 \u00b0 - Step: 0.019 \u00b0 - Step time: 48. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 10Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103203302-Theta - Scale6 10 20 30 40 50 60SL22A400-055-0828 (I) - Cattiite - Mg3(PO4)2\u00b722H2O - WL: 1.5406 - Triclinic - a 6.93200 - b 6.92500 - c 16.15400 - alpha 82.210 - beta 89.700 - gamma 119.510 - Primitive - P-1 (2) - 1 - 666.295 - F30= 16(0.000-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL22A4.raw - Start: 5.000 \u00b0 - End: 89.999 \u00b0 - Step: 0.019 \u00b0 - Step time: 48. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 10Lin (Cps)01002003004002-Theta - Scale6 10 20 30 40 50 60 761       APPENDIX B  Figure B6 \u2013 Experiment 1, Control, Sample SL27A4 (10x) \u2013 K-struvite and Cattiite XRD  SL27A400-055-0828 (I) - Cattiite - Mg3(PO4)2\u00b722H2O - WL: 1.5406 - Triclinic - a 6.93200 - b 6.92500 - c 16.15400 - alpha 82.210 - beta 89.700 - gamma 119.510 - Primitive - P-1 (2) - 1 - 666.295 - F30= 16(0.000-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL27A4.raw - Start: 5.000 \u00b0 - End: 89.999 \u00b0 - Step: 0.019 \u00b0 - Step time: 48. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 10Lin (Cps)01002003004002-Theta - Scale6 10 20 30 40 50 60 7062     APPENDIX C \u2013 Experiment 2: UBC FBR Experiment Data Table C1 \u2013 Experiment 2 Monitoring and Operation Data    Flow pH Temperature Conductivity       Date Time 1A Feed 1B Feed Recycle 1A Feed 2A Reactor 3 Seed Hopper 4 Clarifier 1A Feed 2A Reactor 4 Clarifier 1A Feed 2A Reactor 4 Clarifier ID Run Solids Sampled XRD Analysis Comments 2017 07-Nov 1100 200 20 1800 5.4 8.3 8.3 8.0 13.5 17.6 17.8 44.9 34.2 35.5 SL1 1   Run 1 - familiarizing myself with the system, determining impacts of pH on Sk and pellet formation through daily samples and observations respectively. pH controller is in zone 2A. Seeds added on 9 Nov.  07-Nov 1630 200 20 1800 5.6 8.1 7.8 7.8 15.1 18.4 18.6 44.6 34.8 35.3     08-Nov 1040 200 20 1800 5.6 8.1 7.5 7.5 14.5 17.1 17.3 44.7 35.3 36.4 SL2 *   09-Nov 1100 200 20 1800       18.5    SL3    09-Nov 1545 200 20 1800 5.7 8.2 7.9 7.9 15.3 18 18.4 44.3 37.1 37.3 SL4    10-Nov 630 200 20 1800 5.2 8.3 8.0 7.9 15.6 17.5 17.9 45.9 36 37.5     10-Nov 1600 200 20 1800 5.6 8.5 8.1 8.1 16.2 17.5 17.8 45.6 36.1 37.2 SL5    11-Nov 1030 200 20 1800 5.6 8.3 8.1 8.0 16.2 18 17.8 44.3 36.2 36.8 SL6    11-Nov 1930 200 20 1800 5.6 8.3 7.9 7.9 16 19.2 19.5 43.7 35.6 36.9     12-Nov 1000 200 20 1800 5.7 8.3 8.0 8.0 15.4 17.2 16.9 43.8 35.4 38.4 SL7    12-Nov 1600 200 20 1800 5.7 8.3 8.0 7.9 14.9 17 17 45.1 37.9 39.3     13-Nov 1030 200 20 1800 5.7 8.3 8.0 8.0 14.8 17.6 17.6 44.2 36.3 36.9 SL8    13-Nov 1600 200 20 1800 5.4 8.3 7.9 7.9 14.6 17.1 17.6 45.8 37.6 38.3     14-Nov 745 200 20 1800 5.6 8.3 8.0 8.0 15 17.1 17.5 44.8 37.3 37.8 SL9 * 2A,3  17-Nov 1030 200 20 1800 5.3 8.2 7.8 7.8 14.6 18.6 18.6 42.7 35.4 35.5 SL10 2     17-Nov 1600 200 20 1800 5.5 8.2 7.7 7.6 15.4 18.5 18.9 43.4 35.2 36.2       18-Nov 800 200 20 1800 5.5 8.1 7.8 7.8 15.9 18.4 18.9 42.5 34.8 35.4 SL11      18-Nov 1700 200 20 1800 5.3 8.1 7.8 7.7 16.3 18.2 18.7 42 35.3 36.5       19-Nov 1000 200 20 1800 5.6 8.2 7.9 7.8 16 18.2 18.9 41.6 34.5 35.2 SL12 *     19-Nov 1600 200 20 1800 5.4 8.1 7.7 7.7 14.5 17.9 18.4 44.3 35.2 36.6       20-Nov 900 200 20 1800 5.2 8.1 7.8 7.8 16 18.3 18.8 42.9 36 36.8 SL13      20-Nov 1730 200 20 1800 5.4 8.2 7.8 7.8 15 18.2 18.9 43.4 35.6 36       21-Nov 930 200 20 1800 5.6 8.2 7.8 7.8 15.4 17.5 18 42 36.1 37.2 SL14 * 2A    21-Nov 1600 200 20 1800 5.5 8.2 7.8 7.8 15.3 18.2 18.6 42.4 35.1 36.4       22-Nov 830 200 20 1800 5.5 8.1 7.9 7.9 16.3 18.8 19 42 32.3 33.2 SL15 *     22-Nov 1715 200 20 1800 5.3 8.9 8.5 8.2 16.3 20.3 20.5 43.8 34.6 37       23-Nov 800 200 20 1800 5.3 9.0 8.9 8.9 15.6 18.9 19.3 44.5 36.2 38 SL16 * 2A    23-Nov 1615 200 20 1800 5.4 8.9 8.9 8.8 17.1 20.3 19.8 41.2 34.8 37.4           63    APPENDIX C  Table C1 (cont\u2019d) \u2013 Experiment 2 Monitoring and Operation Data    Flow pH Temperature Conductivity       Date Time 1A Feed 1B Feed Recycle 1A Feed 2A Reactor 3 Seed Hopper 4 Clarifier 1A Feed 2A Reactor 4 Clarifier 1A Feed 2A Reactor 4 Clarifier ID Run Solids Sampled XRD Analysis Comments 2017 04-Dec 800 200 20 1800 3.6 6.6 6.4 6.4 13.9 16.3 16.5 44.6 34.5 34.9 SL17 3 *     04-Dec 1600 200 20 1800 3.5 7.1 7.0 6.9 13 16.9 17.4 47 36 37       05-Dec 1000 200 20 1800 3.6 7.0 6.9 6.9 13.8 15.7 16.1 45.8 37.4 37.1 SL18      05-Dec 1700 200 20 1800 3.6 7.1 6.9 6.9 13.4 16.8 17.3 45.3 36.8 37.6       06-Dec 900 200 20 1800 3.5 7.0 7.0 7.0 12.5 15.3 15.8 46.7 36.9 36.6 SL19 *     06-Dec 1630 200 20 1800 3.6 7.5 7.4 7.4 12.8 17 17.3 46.1 36.7 37       07-Dec 930 200 20 1800 3.6 7.5 7.4 7.4 12.7 16.2 17 46.4 35.5 36.2 SL20      07-Dec 1700 200 20 1800 3.6 7.5 7.4 7.4 12.9 16.8 17.1 46 37 37.8       08-Dec 800 200 20 1800 3.6 7.5 7.4 7.4 14.3 16.1 16.6 47 35.9 35.9 SL21 *     08-Dec 1600 200 20 1800 3.6 8.1 7.8 7.7 14.3 17.1 17.6 47.3 36.2 37.4       09-Dec 900 200 20 1800 3.6 7.9 7.8 7.7 13.9 15.6 16.2 47.1 36.7 37.1 SL22 * 2A,3    09-Dec 1600 200 20 1800 3.6 7.9 7.8 7.7 13.1 17 17.7 46.7 35.7 36.4       10-Dec 800 200 20 1800 3.6 7.9 7.7 7.6 14.1 16.3 16.7 45.3 35 36.3 SL23      10-Dec 1600 200 20 1800 3.6 7.8 7.6 7.6 13.7 17.4 17.8 44.8 35.7 36.9       11-Dec 900 200 20 1800 3.6 7.8 7.6 7.6 13.2 15.9 16 45.1 36.1 36.5 SL24 * 2A,3 Feed Turned Off after sample, left on recycle  11-Dec 1800 200 20 1800 - 7.6 7.6 7.6 - 19.6 20.3 - 35.3 36.4       12-Dec 900 200 20 1800 - 7.6 7.6 7.6 - 19 20 - 35.1 35.2 SL25      14-Dec 800 200 20 1800 - 7.6 7.6 7.6 - 17.8 19.1 - 35.3 34.8 SL26 * 2A   2018 22-Jan 1700 200 20 1800 3.6 8.1 7.9 7.7 14.4 17.8 18.2 46.3 34.2 35.7  4      23-Jan 915 200 20 1800 3.6 7.9 7.7 7.7 15.8 16.6 17.1 46.3 36.4 37.2 SL27 *  Feed Turned Off after sample, left on recycle  24-Jan 800 - - 1800 3.6 7.7 7.6 7.6 13.4 20.3 20.8 47.3 36 36.2 SL28   Feed Turned On after sample  24-Jan 1730 200 20 1800 3.6 8.0 7.7 7.7 14.4 18.5 18.9 46.9 37.3 38.2  *     25-Jan 800 200 20 1800 3.6 8.0 7.7 7.7 14.9 16.7 17.1 46.7 36.2 36.5 SL29 *  Feed Turned Off after sample, left on recycle  26-Jan 800 - - 1800 3.6 7.7 7.7 7.7 14.5 18.6 19.2 46.8 36.4 36.6 SL30 *  Feed Turned On after sample  26-Jan 1930 200 20 1800 3.7 7.9 7.6 7.6 13.4 16.8 17.2 46.1 35.9 36.3       27-Jan 830 200 20 1800 3.7 8.0 7.7 7.6 13.5 16 16.3 46.4 36.9 37.5 SL31 *  Feed Turned Off after sample, left on recycle  28-Jan 830 - - 1800 - 7.7 7.7 7.6 - 19.1 19.8 - 37 37.8 SL32 * 2A    28-Jan 1930 200 20 1800 6.1 8.2 7.9 7.8 13.1 17.4 17.7 35.2 31.3 31.1  5      29-Jan 830 200 20 1800 6.1 8.0 7.8 7.7 14.8 18.2 18.4 34.7 29.6 30.3 SL33 *  Feed Turned Off after sample, left on recycle  30-Jan 830 - - 1800 - 7.7 7.7 7.7 - 19.5 20.3 - 30 29.6 SL34 *  Feed Turned On after sample  30-Jan 1830 200 20 1800 6.1 8.0 7.8 7.7 14.4 17.8 18.2 33.9 29.4 29.6       31-Jan 830 200 20 1800 6.1 8.1 7.8 7.7 12.9 15.4 15.8 34.6 29.8 30.1 SL35 *  Feed Turned Off after sample, left on recycle  01-Feb 830 - - 1800 - 7.8 7.8 7.8 - 19.6 20 - 29.3 30 SL36 *  Feed Turned On after sample  01-Feb 1700 200 20 1800 6.1 8.1 7.7 7.7 13.1 17 17.4 34.4 29.9 30.1       02-Feb 830 200 20 1800 6.1 8.1 7.8 7.8 13.4 16.7 16.9 34.4 29.6 30.3 SL37 *  Feed Turned Off after sample, left on recycle  02-Feb 1900 - - 1800 - 7.9 7.8 7.8 - 20.8 21.5 - 29.8 30 SL38 * 2A    64    APPENDIX C  Table C1 (cont\u2019d) \u2013 Experiment 2 Monitoring and Operation Data    Flow pH Temperature Conductivity       Date Time 1A Feed 1B Feed Recycle 1A Feed 2A Reactor 3 Seed Hopper 4 Clarifier 1A Feed 2A Reactor 4 Clarifier 1A Feed 2A Reactor 4 Clarifier ID Run Solids Sampled XRD Analysis Comments 2018 04-Feb 1700 200 20 1800 6.0 8.0 7.7 7.7 16.2 18.7 19 27.3 17.9 18.01  6      05-Feb 830 200 20 1800 6.0 8.1 7.8 7.7 16.3 18.5 18.8 27.2 17.9 18.02 SL39 *  Feed Turned Off after sample, left on recycle  06-Feb 830 - - 1800 - 7.8 7.8 7.8 - 21.1 21.7 - 17.7 17.8 SL40 *  Feed Turned On after sample  06-Feb 1700 200 20 1800 6.0 8.1 7.8 7.8 16.3 18.4 18.6 27.1 17.7 17.8       07-Feb 900 200 20 1800 5.9 8.1 7.8 7.8 16.3 19 19.4 27.1 17.6 17.8 SL41 *  Feed Turned Off after sample, left on recycle  08-Feb 830 - - 1800 - 7.8 7.8 7.8 - 21.8 22.5 - 17.7 17.7 SL42 *  Feed Turned On after sample  08-Feb 1700 200 20 1800 5.9 8.1 7.8 7.8 15.8 17.7 18.2 27.2 17.6 18       09-Feb 830 200 20 1800 5.9 8.1 7.8 7.8 15.8 17.5 18 27.1 17.7 17.8 SL43 *  Feed Turned Off after sample, left on recycle  10-Feb 830 - - 1800 - 7.9 7.8 7.8 - 18.2 19.1 - 17.7 17.8 SL44 * 2A    11-Feb 1900 200 20 1800 4.8 8.2 7.8 7.7 13 15.8 16.1 47.3 36.1 36.8  7   Start with K Feed  12-Feb 900 200 20 1800 4.9 8.2 7.8 7.8 11.9 13.3 13.3 49.5 40.3 41.3 SL45 *  Switch to NH4 Feed after Sample  12-Feb 1700 200 20 1800 3.5 7.9 7.9 7.9 12.5 16 16.7 16.7 12.5 12.8       13-Feb 900 200 20 1800 3.5 8.0 7.9 7.9 12.6 13.9 14.3 10.1 8.9 8.57 SL46 *  Switch to K Feed after Sample  13-Feb 1700 200 20 1800 4.8 8.1 7.8 7.8 12.1 18.9 16.4 51.1 35.3 36.5       14-Feb 900 200 20 1800 4.9 8.1 7.8 7.8 11.4 14.3 14.6 50.5 42.9 43.2 SL47 *  Switch to NH4 Feed after Sample  16-Feb 2330 200 20 1800 3.4 8.1 8.1 8.0 12.8 16.8 17.4 10 8.4 8.4 SL48 *  Switch to K Feed after Sample  17-Feb 1700 200 20 1800 4.8 8.0 7.8 7.7 13.2 17.5 18 48.4 36.7 36.8      18-Feb 1000 200 20 1800 4.9 8.0 7.9 7.9 11.2 14.1 14.6 50.4 41.3 41.5 SL49 *  Switch to NH4 Feed after Sample  18-Feb 1600 200 20 1800 3.5 8.1 8.0 8.0 13.4 17.2 17.6 9.7 14.5 14.9       19-Feb 900 200 20 1800 3.5 8.2 8.2 8.1 10 10.8 11.1 10.3 9.1 8.6 SL50 * 2A   65    APPENDIX C  Table C2 \u2013 Experiment 2 Sample Data Run ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L)  ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L) 1 SL1 1A 311.5 42.9 14406.3   SL1 1B 3.5 5718.7 65.9  SL2 1A 321.6 3.2 14303.8   SL2 1B 3.7 5567.0   SL3 1A 324.6 1.9 15335.6   SL3 1B 3.6 5587.0   SL4 1A 324.6 2.3 15283.0   SL4 1B 3.7 5011.8   SL5 1A 325.6 3.2 15395.9   SL5 1B 4.0 5883.8   SL6 1A 326.6 4.7 15826.9   SL6 1B 4.1 5978.8   SL7 1A 328.6 2.7 15061.5   SL7 1B 3.6 5518.7   SL8 1A 324.6 7.8 15258.8   SL8 1B 4.5 5800.4   SL9 1A 324.6 5.2 15141.0   SL9 1B 3.7 5803.8 60.6  2 SL10 1A 312.5 5.4 14144.5   SL10 1B 4.3 6002.2 54.8  SL11 1A 305.4 12.8 14292.5   SL11 1B 4.1 6128.9   SL12 1A 308.4 5.6 14679.9   SL12 1B 3.7 6113.9   SL13 1A 313.5 2.8 14685.5   SL13 1B 3.7 6140.5   SL14 1A 357.8 43.2 13702.6   SL14 1B 3.7 6368.9   SL15 1A 310.5 7.1 14367.2   SL15 1B 3.9 6190.5   SL16 1A 311.5 4.0 13928.8   SL16 1B 3.7 6227.2 63.0  3 SL17 1A 265.1 545.2 13308.9   SL17 1B 4.1 25.0 30.1  SL18 1A 265.1 553.6 13164.0   SL18 1B 4.1 5.0   SL19 1A 265.1 535.5 12566.7   SL19 1B 3.8 2.7   SL20 1A 269.1 544.4 13114.5   SL20 1B 3.8 10.4   SL21 1A 264.1 561.1 13141.1   SL21 1B 3.7 6.9   SL22 1A 265.1 534.4 13540.1   SL22 1B 3.7 4.0   SL23 1A 262.1 474.6 13080.8   SL23 1B 3.8 1.7   SL24 1A 263.1 504.1 13845.1   SL24 1B 3.7 2.0 11.4  4 SL27 1A 441.0 768.2 13037.0   SL27 1B 0.0 -0.8 -1.2  SL31 1A 409.0 761.6 13017.6   SL31 1B 0.0 0.1 1.2  5 SL33 1A 401.0 758.2 9806.3   SL33 1B 0.0 -0.1 -1.4  SL37 1A 402.0 749.5 10043.5   SL37 1B 0.2 -0.6 6.3  6 SL39 1A 426.0 592.7 7851.6   SL39 1B 0.1 -0.2 3.0  SL43 1A 416.0 592.4 7944.5   SL43 1B 0.0 -0.2 -0.3  7 SL45 1A 459.0 727.1 14940.2 nd  SL45 1B 0.0 1.5 5.6 nd SL46 1A 173.0 294.6 26.0 818.8        SL49 1A 551.0 673.8 14845.3 nd        SL50 1A 165.0 224.7 5.1 805.0  SL50 1B 0.0 -0.5 -0.3 nd *1A \u2013 Main Feed, 1B \u2013 Secondary Feed, 2A \u2013 Active Zone (@pH control), 3 \u2013 Seed Hopper (@top of reactor), 4 - Clarifier   66    APPENDIX C Table C2 (cont\u2019d) \u2013 Experiment 2 Sample Data Run ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L) pH Temperature Sk  ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L)  ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L) pH Temperature Sk 1 SL1 2A 57.0 273.9 11366.6  8.3 17.6 1.1  SL1 3 58.4 248.9 11885.8   SL1 4 59.0 276.7 12579.7  8.0 17.8 0.9 SL2 2A 106.8 374.2 13132.9  8.1 17.1 1.2  SL2 3 104.8 373.8 13471.3   SL2 4 110.9 381.6 14953.5  7.5 17.3 0.8                  SL3 4 110.9 367.4 14462.4     SL4 2A 107.9 381.9 13477.5  8.2 18.0 1.4  SL4 3 104.8 367.9 13573.1   SL4 4 115.9 374.1 14564.5  7.9 18.4 1.1 SL5 2A 39.0 309.6 13643.4  8.5 17.5 1.1  SL5 3 37.3 319.8 13379.3   SL5 4 38.4 320.6 14904.1  8.1 17.8 0.9 SL6 2A 39.4 313.4 13674.5  8.3 18.0 1.0  SL6 3 35.0 323.8 13615.5   SL6 4 34.4 323.2 14714.2  8.0 17.8 0.8 SL7 2A 52.6 329.5 13659.5  8.3 17.2 1.1  SL7 3 47.9 328.6 13808.4   SL7 4 50.5 334.5 13977.4  8.0 16.9 0.9 SL8 2A 53.2 340.2 13775.4  8.3 17.6 1.2  SL8 3 52.1 322.2 13077.4   SL8 4 53.2 342.5 14445.4  8.0 17.6 0.9 SL9 2A 49.5 344.6 13779.2  8.3 17.1 1.1  SL9 3 44.9 340.8 13967.4   SL9 4 47.9 337.2 14321.9  8.0 17.5 0.9 2 SL10 2A 96.8 413.5 12970.3  8.2 18.6 1.3  SL10 3 70.1 382.9 12900.4   SL10 4 72.9 390.7 13550.7  7.8 18.6 0.9 SL11 2A 82.7 412.2 12256.0  8.1 18.4 1.2  SL11 3 77.1 382.4 13203.8   SL11 4 83.7 406.2 13700.8  7.8 18.9 0.9 SL12 2A 74.2 377.4 12621.6  8.2 18.2 1.2  SL12 3 73.7 414.5 12798.0   SL12 4 74.9 413.6 13645.0  7.8 18.9 0.9 SL13 2A 105.8 413.0 12943.8  8.1 18.3 1.2  SL13 3 102.8 426.1 13364.1   SL13 4 104.8 414.7 13858.7  7.8 18.8 1.0 SL14 2A 93.7 425.6 12754.1  8.2 17.5 1.3  SL14 3 91.6 365.7 13517.3   SL14 4 94.6 414.1 14098.5  7.8 18.0 0.9 SL15 2A 88.3 404.0 12888.2  8.1 18.8 1.2  SL15 3 82.8 400.5 13222.6   SL15 4 89.0 396.3 13703.7  7.9 19.0 1.0 SL16 2A 9.3 317.4 12521.0  9.0 18.9 1.1  SL16 3 7.6 351.3 13522.6   SL16 4 7.6 330.8 13797.2  8.9 19.3 0.9 3 SL17 2A 322.6 545.1 11810.7  6.6 16.3 0.5  SL17 3 288.3 553.6 12758.0   SL17 4 291.3 557.6 13727.3  6.4 16.5 0.4 SL18 2A 273.2 518.3 12121.5  7.0 15.7 0.7  SL18 3 268.1 512.9 12374.1   SL18 4 271.2 523.6 13754.5  6.9 16.1 0.7 SL19 2A 261.1 545.2 12112.0  7.0 15.3 0.7  SL19 3 259.1 530.1 12896.8   SL19 4 261.1 493.3 13604.9  7.0 15.8 0.7 SL20 2A 239.9 530.7 12220.7  7.5 16.2 1.1  SL20 3 241.9 489.7 12540.9   SL20 4 243.9 477.4 13420.8  7.4 17.0 1.0 SL21 2A 236.9 521.3 12421.6  7.5 16.1 1.1  SL21 3 239.9 525.8 12884.6   SL21 4 237.9 499.1 13816.6  7.4 16.6 1.0 SL22 2A 142.1 431.9 11826.6  7.9 15.6 1.2  SL22 3 140.1 225.2 12651.5   SL22 4 144.1 415.1 13448.7  7.7 16.2 1.1 SL23 2A 140.1 420.2 11874.5  7.9 16.3 1.2  SL23 3 137.1 419.1 12673.6   SL23 4 139.1 427.0 13236.2  7.6 16.7 1.0 SL24 2A 145.2 436.9 12132.7  7.8 15.9 1.1  SL24 3 141.1 433.1 12778.1   SL24 4 143.1 425.4 13397.1  7.6 16.0 1.0 SL25 2A 149.2 442.9 12749.4  7.6 19.0 1.0  SL25 3 151.2 471.7 12376.2   SL25 4 151.2 451.3 13595.6  7.6 20.0 1.0 SL26 2A 163.0 444.3 13417.4  7.6 17.8 1.0  SL26 3 157.0 451.1 13494.7   SL26 4 157.0 442.9 13606.6  7.6 19.1 1.0 4 SL27 2A 244.0 635.2 12378.5  7.9 16.6 1.5  SL27 3 152.5 632.0 12661.8   SL27 4 121.9 651.1 12433.9  7.7 17.1 1.1 SL28 2A 192.0 650.1 12461.3  7.7 20.3 1.2  SL28 3 182.5 636.5 12976.1   SL28 4 119.9 642.7 12827.0  7.6 20.8 1.0 SL29 2A 205.0 626.8 12239.3  8.0 16.7 1.6  SL29 3 157.5 628.1 12704.7   SL29 4 117.0 635.1 12930.1  7.7 17.1 1.0 SL30 2A 177.0 634.9 12501.7  7.7 18.6 1.2  SL30 3 147.6 633.1 12814.6   SL30 4 113.0 644.8 12496.6  7.7 19.2 1.0 SL31 2A 188.0 620.8 12412.4  8.0 16.0 1.5  SL31 3 152.6 655.1 12629.0   SL31 4 113.0 641.1 12933.8  7.6 16.3 1.0 SL32 2A 146.0 607.6 12400.1  7.7 19.1 1.1  SL32 3 120.6 626.5 13144.9   SL32 4 94.2 624.7 12573.7  7.6 19.8 0.9 5 SL33 2A 172.0 632.9 9431.8  8.0 18.2 1.4  SL33 3 157.6 652.6 9665.5   SL33 4 104.1 624.7 9931.7  7.7 18.4 1.0 SL34 2A 149.0 611.8 9761.0  7.7 19.5 1.1  SL34 3 126.7 639.3 9680.3   SL34 4 102.1 632.3 9854.0  7.7 20.3 1.0 SL35 2A 157.0 609.0 9666.2  8.1 15.4 1.5  SL35 3 145.7 632.0 9673.8   SL35 4 114.1 630.5 9717.7  7.7 15.8 1.0 SL36 2A 133.0 613.5 9708.7  7.8 19.6 1.1  SL36 3 107.7 606.5 9719.2   SL36 4 90.8 622.6 9965.8  7.8 20.0 1.0 SL37 2A 172.0 626.7 9870.9  8.1 16.7 1.6  SL37 3 153.7 630.3 9256.3   SL37 4 158.2 635.7 9879.6  7.8 16.9 1.2 SL38 2A 119.0 606.6 9682.6  7.9 20.8 1.1  SL38 3 78.8 617.6 9849.1   SL38 4 61.7 590.4 8793.4  7.8 21.5 0.9 67    APPENDIX C  Table C2 (cont\u2019d) \u2013 Experiment 2 Sample Data Run ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L) pH Temperature Sk  ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L)  ID P (mg\/L) Mg (mg\/L) K (mg\/L) N-NH4 (mg\/L) pH Temperature Sk 6 SL39 2A 208.0 438.4 7605.9   8.1 18.5 1.5  SL39 3 212.8 453.0 7356.8    SL39 4 127.2 455.9 6755.7   7.7 18.8 0.9 SL40 2A 271.0 428.0 8030.0   7.8 21.1 1.3  SL40 3 199.8 423.8 7338.6    SL40 4 132.2 423.9 7466.9   7.8 21.7 1.0 SL41 2A 216.0 450.0 7773.9   8.1 19.0 1.5  SL41 3 240.8 441.0 7349.4    SL41 4 134.3 338.3 7442.4   7.8 19.4 1.0 SL42 2A 231.0 394.5 8097.2   7.8 21.8 1.2  SL42 3 143.9 408.0 7512.6    SL42 4 134.3 301.3 7555.2   7.8 22.5 0.9 SL43 2A 203.0 437.6 7940.8   8.1 17.5 1.5  SL43 3 253.9 447.9 7658.0    SL43 4 115.3 311.4 7665.7   7.8 18.0 0.9 SL44 2A 190.0 382.2 8083.7   7.9 18.2 1.2   SL44 3 143.9 388.2 7653.7     SL44 4 102.3 264.2 7731.3   7.8 19.1 0.9 7 SL45 2A 137.0 556.7 14093.5 nd 8.2 13.3 1.6  SL45 3 174.9 559.0 14489.0 nd  SL45 4 68.7 416.6 14340.3 nd 7.8 13.3 0.9 SL46 2A 7.0 28.7 1402.3 778.7 8.0 13.9 0.2  SL46 3 3.0 20.5 385.2 762.1  SL46 4 1.9 49.1 427.6 758.7 7.9 14.3 0.0 SL47 2A 129.0 539.2 14064.0 nd 8.1 14.3 1.5  SL47 3 98.0 566.2 14561.2 nd  SL47 4 69.1 387.9 14216.4 nd 7.8 14.6 0.9 SL48 2A 5.3 28.2 1524.4 729.8 8.1 16.8 0.2  SL48 3 2.2 14.7 511.2 753.8  SL48 4 0.0 49.1 508.2 757.3 8.0 17.4 0.0 SL49 2A 114.0 541.0 14069.8 nd 8.0 14.1 1.3  SL49 3 119.0 561.3 14234.0 nd  SL49 4 51.4 353.5 14114.1 nd 7.9 14.6 0.8 SL50 2A 3.4 12.9 1415.3 738.5 8.2 10.8 0.1   SL50 3 1.4 7.8 368.6 822.5   SL50 4 1.1 48.8 423.8 766.0 8.1 11.1 0.0 *1A \u2013 Main Feed, 1B \u2013 Secondary Feed, 2A \u2013 Active Zone (@pH control), 3 \u2013 Seed Hopper (@top of reactor), 4 - Clarifier    68    APPENDIX C Table C3 \u2013 Experiment 2 Results  % Removal (Effluent v. Feed)   Molar Concentrations (@ Injector, based on flows), mM Molar Ratio's (@ Injector based on flows), mM ID P Mg K* NH4* Operation pH (@controller) P Mg K N P:K P:Mg P:N SL1 80% 47% 8%   8.3 5.5 22.9 656.4  119.1 4.1  SL2 62% 27% -9%   8.1 8.5 30.6 765.7  89.8 3.6  SL3 62% 30% -5%    8.5 29.6 743.1  87.1 3.5  SL4 61% 28% -6%   8.2 8.8 30.1 747.8  84.8 3.4  SL5 87% 38% -8%   8.5 4.3 26.1 763.4  176.8 6.0  SL6 88% 38% -7%   8.3 4.1 26.3 754.7  184.8 6.4  SL7 83% 36% -2%   8.3 5.0 27.2 720.8  143.5 5.4  SL8 82% 34% -5%   8.3 5.2 27.7 742.3  143.3 5.4  SL9 84% 35% -4%   8.3 4.9 27.4 736.6  151.3 5.6  SL10 75% 32% -5%   8.2 6.3 31.5 696.7  111.0 5.0  SL11 71% 29% -6%   8.1 6.9 32.7 703.6  101.9 4.7  SL12 74% 28% -5%   8.2 6.4 33.2 701.1  109.6 5.2  SL13 64% 27% -7%   8.1 8.1 33.3 710.9  87.4 4.1  SL14 67% 28% -9%   8.2 7.5 33.3 722.0  95.8 4.4  SL15 69% 31% -6%   8.1 7.2 32.0 703.8  97.5 4.4  SL16 97% 42% -6%   9.0 2.5 27.1 708.1  284.8 10.9  SL17 -21% -15% -14%   6.6 18.6 45.7 699.5  37.6 2.5  SL18 -12% -8% -14%   7.0 17.5 43.2 700.8  40.2 2.5  SL19 -8% -2% -13%   7.0 16.9 40.9 693.9  41.1 2.4  SL20 -1% 1% -12%   7.5 15.9 39.7 685.4  43.2 2.5  SL21 1% -3% -15%   7.5 15.5 41.3 703.7  45.3 2.7  SL22 40% 14% -12%   7.9 10.1 35.1 686.7  68.1 3.5  SL23 42% 12% -10%   7.9 9.8 36.0 676.9  69.2 3.7  SL24 41% 12% -11%   7.8 10.0 35.9 684.3  68.3 3.6  SL25 37% 7% -13%  Recycle On 7.6 10.5 37.8 693.5  66.1 3.6  SL26 35% 8% -13%  Recycle On 7.6 10.8 37.2 694.0  64.1 3.4  SL27 68% 6% -5%   7.9 9.8 54.5 639.3  65.1 5.6  SL28 69% 8% -8%  Recycle On 7.7 9.7 53.9 657.4  67.7 5.6  SL29 70% 9% -9%   8.0 9.5 53.3 662.1  69.4 5.6  SL30 71% 7% -6%  Recycle On 7.7 9.3 54.1 642.1  69.0 5.8  SL31 71% 8% -9%   8.0 9.3 53.8 662.3  71.2 5.8  SL32 76% 10% -6%  Recycle On 7.7 8.2 52.6 645.7  78.6 6.4  SL33 71% 9% -10%   8.0 8.6 52.5 508.2  58.9 6.1  SL34 72% 8% -9%  Recycle On 7.7 8.5 53.0 504.6  59.2 6.2  SL35 69% 8% -8%   8.1 9.2 52.9 498.4  54.1 5.7  SL36 75% 9% -10%  Recycle On 7.8 7.9 52.3 509.8  64.8 6.7  SL37 57% 7% -9%   8.1 11.8 53.3 505.8  43.0 4.5  SL38 83% 14% 3%  Recycle On 7.9 6.2 49.9 455.8  73.9 8.1  SL39 67% 15% 6%   8.1 10.1 38.7 351.7  34.8 3.8  SL40 65% 21% -4%  Recycle On 7.8 10.4 36.3 384.4  37.0 3.5  SL41 65% 37% -4%   8.1 10.5 29.9 383.3  36.5 2.8  SL42 65% 44% -5%  Recycle On 7.8 10.5 27.2 388.5  37.0 2.6  SL43 70% 42% -7%   8.1 9.4 27.9 393.6  41.8 3.0  SL44 73% 51% -8%  Recycle On 7.9 8.7 24.4 396.6  45.8 2.8  SL45 85% 35% -6%  K Feed On 8.2 7.2 28.7 929.0  128.2 4.0  SL46 99% 79%  -3% NH4 Feed On 8.0 1.2 4.5 24.9 49.3 20.8 3.8 41.0 SL47 85% 39% -5%  K Feed On 8.1 7.3 27.0 921.9  126.8 3.7  SL48 100% 79%  -3% NH4 Feed On 8.1 1.1 4.5 29.6 49.2 27.2 4.2 45.1 SL49 89% 44% -4%  K Feed On 8.0 6.2 25.0 915.9  146.8 4.0  SL50 99% 79%  -4% NH4 Feed On 8.2 1.2 4.5 24.7 49.7 21.5 3.9 43.2 *Due to low changes in concentration of K and NH4, error in diluting high concentrations of K, and equipment measurement accuracy, K removal is determined to be negligible.69    APPENDIX D \u2013 Experiment 2: UBC FBR Experiment Solids Analysis  Table D1 \u2013 Experiment 2 Solids Analysis Data and Results  Run Experiment 2 ID P (mM) Mg (mM) K (mM) N (mM) XRD Analysis 1 SL9_2A 5.3 4.4 4.1  K-struvite 2 SL14_2A 4.0 4.1 3.1  K-struvite SL16_2A 4.4 4.2 3.5  K-struvite 3 SL22_2A 4.0 4.0 3.0  K-struvite SL24_2A 4.7 4.2 3.6  K-struvite SL26_2A 4.0 4.0 3.1  K-struvite 4 SL32_2A 4.1 4.1 3.1  K-struvite 5 SL38_2A 4.2 4.1 3.2  K-struvite 6 SL44_2A 4.0 4.1 2.9  K-struvite 7 SL50_2A 11.7 16.6 1.2 5.4 K-struvite, NH4-struvite K-struvite and NH4-struvite have 1:1:1 molar ratios. Measurement errors and impurities such as Cattiite (Mg3(PO4)2:22H2O) may explain why the molar concentration of potassium of ammonia are not equal to that of phosphorus and magnesium.   Figure D1 \u2013 Experiment 2, Run 1, Sample SL9_2A (10x) \u2013 K-struvite XRDSL9_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL9_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 1Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 5070    APPENDIX D  Figure D2 \u2013 Experiment 2, Run 2, Sample SL14_2A (10x) \u2013 K-struvite XRD   Figure D3 \u2013 Experiment 2, Run 2, Sample SL16_2A (10x) \u2013 K-struvite XRD SL14_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL14_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 50SL16_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL16_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 5071    APPENDIX D  Figure D4 \u2013 Experiment 2, Run 3, Sample SL22_2A (10x) \u2013 K-struvite XRD   Figure D5 \u2013 Experiment 2, Run 3, Sample SL24_2A (10x) \u2013 K-struvite XRD SL22_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL22_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 50SL24_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL24_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 5072    APPENDIX D   Figure D6 \u2013 Experiment 2, Run 3, Sample SL26_2A (10x) \u2013 K-struvite XRD   Figure D7 \u2013 Experiment 2, Run 4, Sample SL32_2A (10x) \u2013 K-struvite XRD SL26_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alpha 90.000 - beta 90.000 - gamma 90.000 - Primitive - Pm21n (31) - 2 - 470.629 File: SL26_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: Lin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103202-Theta - Scale5 10 20 30 40 50SL32_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - Y: 35.26 % - d x by: 1. - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alphOperations: ImportFile: SL32_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - GeLin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103203303402-Theta - Scale5 10 20 30 40 5073    APPENDIX D  Figure D8 \u2013 Experiment 2, Run 5, Sample SL38_2A (10x) \u2013 K-struvite XRD   Figure D9 \u2013 Experiment 2, Run 6, Sample SL44_2A (10x) \u2013 K-struvite XRD SL38_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - Y: 35.26 % - d x by: 1. - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alphOperations: ImportFile: SL38_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - GeLin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103203303402-Theta - Scale5 10 20 30 40 50SL44_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - Y: 35.26 % - d x by: 1. - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alphOperations: ImportFile: SL44_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - GeLin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103203303402-Theta - Scale5 10 20 30 40 5074    APPENDIX D   Figure D10 \u2013 Experiment 2, Run 7, Sample SL50_2A (10x) \u2013 K-struvite and NH4-Struvite XRD  Figure D11 \u2013 Experiment 2, Run 7, Sample SL50_2A \u2013 K-struvite and NH4-Struvite SL50_2A00-035-0812 (*) - Struvite-K, syn - KMgPO4\u00b76H2O - Y: 13.23 % - d x by: 1. - WL: 1.5406 - Orthorhombic - a 6.87910 - b 11.10010 - c 6.16340 - alph01-077-2303 (*) - Struvite, syn - MgNH4PO4(H2O)6 - Y: 75.23 % - d x by: 1. - WL: 1.5406 - Orthorhombic - a 6.95500 - b 6.14200 - c 11.21800 - alpOperations: ImportFile: SL50_2A.raw - Start: 5.000 \u00b0 - End: 89.994 \u00b0 - Step: 0.019 \u00b0 - Step time: 48.3 s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - GeLin (Cps)01020304050607080901001101201301401501601701801902002102202302402502602702802903003103203303403503603703803904004104204304404502-Theta - Scale5 10 20 30 40 50SL50_2A (3).raw_12Th Degrees5250484644424038363432302826242220181614121086Counts34,00032,00030,00028,00026,00024,00022,00020,00018,00016,00014,00012,00010,0008,0006,0004,0002,0000-2,000-4,000-6,000Struvite 76.68 %Struvite-(K) 23.32 %75  ","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/hasType":[{"value":"Thesis\/Dissertation","type":"literal","lang":"en"}],"http:\/\/vivoweb.org\/ontology\/core#dateIssued":[{"value":"2018-09","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/isShownAt":[{"value":"10.14288\/1.0371026","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/language":[{"value":"eng","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#degreeDiscipline":[{"value":"Civil Engineering","type":"literal","lang":"en"}],"http:\/\/www.europeana.eu\/schemas\/edm\/provider":[{"value":"Vancouver : University of British Columbia Library","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/publisher":[{"value":"University of British Columbia","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/rights":[{"value":"Attribution-NonCommercial-NoDerivatives 4.0 International","type":"literal","lang":"*"}],"https:\/\/open.library.ubc.ca\/terms#rightsURI":[{"value":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/","type":"literal","lang":"*"}],"https:\/\/open.library.ubc.ca\/terms#scholarLevel":[{"value":"Graduate","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/title":[{"value":"A UBC fluidized bed reactor investigation of K-struvite","type":"literal","lang":"en"}],"http:\/\/purl.org\/dc\/terms\/type":[{"value":"Text","type":"literal","lang":"en"}],"https:\/\/open.library.ubc.ca\/terms#identifierURI":[{"value":"http:\/\/hdl.handle.net\/2429\/66788","type":"literal","lang":"en"}]}}