Low plant available phosphorus limits legume growth and biological nitrogen fixation (BNF). This study examined, under controlled conditions, the relationship between soil phosphorus and alfalfa and soybean BNF on two contrasting low-P soils (Ontario and Nova Scotia) from organic dairy farms. Soluble P was applied up to 135 mg P kg-1. An optimum range of 45 to 90 mg kg-1 applied P increased soybean plant growth, nodulation, N and P uptake and BNF. Significant effects of soil type reflected greater N supplying ability and lower P sorption for the Ontario soil. Alfalfa response to soluble P application was not as apparent. In addition three potentially organically acceptable amendments (MSW compost, Crystal Green® struvite and partially solubilized rock phosphate) were evaluated as alternate sources of plant available P. Compost and struvite, applied at moderate rates, sufficiently supplied P to increase plant growth and BNF comparably to that found for soluble P fertilizer.

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Magnesium oxide (MgO) is a cost-effective and environmentally sustainable alternative to magnesium chloride (MgCl2) and sodium hydroxide (NaOH) used for sidestream struvite recovery from anaerobically digested supernatant (centrate) through the Pearl® process. MgO is produced from magnesite (MgCO3) calcination, and different calcination conditions can alter the quality and characteristics of the MgO product. It was hypothesized that the insolubility of MgO could provide a "slowly available" form of Mg2+ in the reactor and consequently allow the reactor to be operated beyond design phosphorus (P) reactor loading. MgO has been utilized in other P recovery technologies, e.g. the Phospaq™ Process, but operation and performance of MgO using a full-scale Pearl® 500 fluidized bed reactor was investigated. Performance at rated reactor loading utilizing MgO was initially comparable to baseline conventional MgCl2 reactor operation, ≥50% struvite yield (P recovered/theoretical P recovery) and ≥70% total phosphorus (TP) removal. However, the pilot reactor operated at 2X reactor loading showed comparable results to baseline performance at 1.5X reactor loading. During the full-scale pilot, optimization of the reactor utilizing MgO was limited by the struvite product size that the struvite post-processing equipment could effectively harvest. Additionally, the MgO characteristics due to calcination conditions were hypothesized to affect struvite precipitation kinetics. In struvite precipitation jar testing, MgO products were used to analyze the saturation index, measure precipitation kinetics, and understand the effect that MgO hydration and reactivity had on struvite precipitation. Jar testing showed that initial P removal increased with increasing MgO product reactivity. The most reactive MgO used, Timab AK98, showed 1-40% P removal and substantial decrease in solution saturation index immediately after dosing MgO to centrate. The slower P removal and decrease in saturation index observed with the less reactive material suggests that MgO can provide a "slowly available" Mg2+ reserve throughout the struvite precipitation reaction. / Master of Science / Phosphorus is an essential element for human, plant and animal health. Necessary bodily functions cannot be performed without inputting phosphorus to cell metabolic pathways, such as cell repair and formation of nucleic acids, bone mineral and stored energy. Phosphates are the most common form of phosphorus found in the environment and are a component of many common substances, such as detergents, fertilizers, food and urine. Due to the increasing population and food demand the need for phosphorus-based fertilizers has soared since the 1940s. In 2018, 240 megatons of phosphate rock were mined, and 17 megatons of phosphorus were extracted from mined ore. 15 megatons of the extracted phosphorus were used in fertilizer production. Because of phosphorus loss from the soil and inefficient agro-practices, only 20% of the extracted phosphorus is consumed by humans and animals from food and little is then recycled from our waste systems. There is a major gap in the agricultural phosphorus cycle that is necessary to address with sustainable practices (Oster, M. et al. 2018). Phosphorus can be recovered from wastewater in the form of struvite, which is a mineral that can be utilized a slow-release fertilizer. Conventional methods of phosphorus recovery from wastewater have the potential to be costly. By utilizing an alternative chemical, struvite recovery can be more cost-effective and environmentally sustainable.

Struvite is a salt that is formed out of  Mg2+,NH4+ and PO43- and it crystallizes in form of MgNH4PO4.6H2O. Struvite‟s (magnesium ammonium phosphate or MAP) precipitation has recently been regarded as an interesting technique to remove phosphate and ammonium from waste water. The high elimination rates and the possibility of recycling the struvite as a direct slow release fertilizer make this process feasible and appealing. However, the costs due to the raw chemicals needed are drawbacks that leave aside the application of the process in some facilities. The MAP biological dissolution makes possible a recycling of magnesium and phosphate, a fact that reduces the process‟s costs and will help making it even more feasible and environmentally friend. This thesis goes also through the parameters, reactions and different techniques that optimize the struvite precipitation process.

Dissolved compounds and ions, including mineral elements and products of microbial metabolism, are present in many cheeses in relatively high concentrations. These dissolved substances may precipitate from the aqueous phase of cheese to form sparingly soluble crystals that can impart a crunchy, gritty, or sandy texture on the cheese. In the present work, optical and diffractometric methods were optimized for use with cheese samples to identify crystal phases in several cheese varieties. These techniques, which included powder X-ray diffractometry (PXRD), single crystal X-ray diffractometry (SCXRD), and petrographic microscopy (PM) have traditionally been used on geological specimens that are quite different from the cheese samples used in the present study. Nonetheless, these techniques were successfully used to gain valuable insight into crystal development in cheese. Powder X-ray diffractometry was optimized to minimize the occurrence of artifacts that may occur due to the high water content and low crystallinity of some cheese samples. The use of enhanced sample preparation techniques facilitated the identification of organic and inorganic crystal phases such as tyrosine, leucine, brushite (CaHPO4·2H2O), and calcite (CaCO3) in hard and soft cheeses. SCXRD was used to determine the crystal structures of ikaite and struvite, which had been tentatively identified in washed-rind cheese using PXRD. PM was used to observe morphological and optical properties of crystals in white mold cheese and washed-rind cheese. In two subsequent aging studies, PXRD was used to determine the approximate timing of crystal nucleation in the rinds of white mold cheese and washed-rind cheese. These observations were paired with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) data to demonstrate that the onset of crystallization in the rinds coincided with a diffusion phenomenon in which mineral ions diffused from the center of the cheese and became concentrated in the rind. PM observations demonstrated that maximum crystal size in the rinds generally increased as aging progressed. These observations will be useful in future work that investigates the impact of crystallization on sensory properties of cheese.

A presente pesquisa estudou a viabilidade do emprego de sais de magnésio em estações de tratamento de esgoto sanitário visando a remoção do fósforo, bem como a produção de estruvita, mineral que pode ser utilizado diretamente no solo como fertilizante. As estações estudadas nesta pesquisa foram a Estação de Tratamento de Esgoto Sanitário de Franca-SP e a Estação de Tratamento de Esgoto Sanitário Jardim das Flores, localizada no município de Rio Claro-SP, e a Estação de Tratamento de Esgoto Sanitário Piçarrão, no município de Campinas. No caso da ETE Jardim das Flores (Rio Claro-SP), observou a possibilidade do emprego de sais de magnésio para se remover fósforo no efluente dos reatores UASB. Com ensaios de Jar-Test, atingiu-se cerca 49% de remoção de fosfato na amostra precipitada por gravidade e cerca de 90% na amostra centrifugada. No caso da ETE-Franca-SP, constatou-se, apesar do emprego de sais de magnésio não ter sido viável, verificou-se os benefícios do emprego de cloreto férrico em estações de tratamento de esgoto sanitário. / The present research studied the use of magnesium salts to remove phosphorus. With the phosphorus removal, magnesium salts, produce, as well, struvite, mineral that can be use directly on soil as fertilizer. The wastewater treatment plants objects of studies in this research was Wastewater Treatment Plant of Franca (SABESP) city Wastewater Treatment Plant of Jardim das Flores (Foz do Brasil), at Rio Claro city, and Wastewater Treatment Plant of Piçarrão (SANASA), at Campinas city. All three WWTP\'s are at São Paulo state, Brazil. In WWTP Jardim das Flores/Foz do Brasil (Rio Claro-SP), the results shown the viability of magnesium salts use at effluent of UASB reactors. In Jar-test essays, the phosphorus removal reached among 49% and in centrifuged samples, phosphorus removal was among 90%. In WWTP Franca-SP/SABESP, the results shown the benefits of iron salts in wastewater treatment.

A presente pesquisa estudou a viabilidade do emprego de sais de magnésio em estações de tratamento de esgoto sanitário visando a remoção do fósforo, bem como a produção de estruvita, mineral que pode ser utilizado diretamente no solo como fertilizante. As estações estudadas nesta pesquisa foram a Estação de Tratamento de Esgoto Sanitário de Franca-SP e a Estação de Tratamento de Esgoto Sanitário Jardim das Flores, localizada no município de Rio Claro-SP, e a Estação de Tratamento de Esgoto Sanitário Piçarrão, no município de Campinas. No caso da ETE Jardim das Flores (Rio Claro-SP), observou a possibilidade do emprego de sais de magnésio para se remover fósforo no efluente dos reatores UASB. Com ensaios de Jar-Test, atingiu-se cerca 49% de remoção de fosfato na amostra precipitada por gravidade e cerca de 90% na amostra centrifugada. No caso da ETE-Franca-SP, constatou-se, apesar do emprego de sais de magnésio não ter sido viável, verificou-se os benefícios do emprego de cloreto férrico em estações de tratamento de esgoto sanitário. / The present research studied the use of magnesium salts to remove phosphorus. With the phosphorus removal, magnesium salts, produce, as well, struvite, mineral that can be use directly on soil as fertilizer. The wastewater treatment plants objects of studies in this research was Wastewater Treatment Plant of Franca (SABESP) city Wastewater Treatment Plant of Jardim das Flores (Foz do Brasil), at Rio Claro city, and Wastewater Treatment Plant of Piçarrão (SANASA), at Campinas city. All three WWTP\'s are at São Paulo state, Brazil. In WWTP Jardim das Flores/Foz do Brasil (Rio Claro-SP), the results shown the viability of magnesium salts use at effluent of UASB reactors. In Jar-test essays, the phosphorus removal reached among 49% and in centrifuged samples, phosphorus removal was among 90%. In WWTP Franca-SP/SABESP, the results shown the benefits of iron salts in wastewater treatment.

Hog manure phosphorus (P) can be recovered as struvite or magnesium ammonium phosphate hexahydrate (MgNH4PO4∙6H2O). The recovered struvite has slow-release properties and may be used as a P-source for crops. Two pot experiments were conducted to evaluate the agronomic effectiveness and seedling toxicity of liquid hog manure-recovered struvite for canola (Brassica spp.) and wheat (Triticum aestivum). While wheat was non-responsive to P application, canola dry matter yield (DMY) from struvite (1.9 g kg-1) was similar to that from monoammonium phosphate (MAP) (1.8 g kg-1) and coated-monoammonium phosphate (CMAP) (1.7 g kg-1). Importantly, when P was seed-placed at the higher rate (15 mg kg-1), canola seedling emergence was significantly greater with struvite (90%) and CMAP (85%) than with MAP (60%). The results demonstrate the potential of struvite as an effective P-source for canola in P-deficient soils, which can be safely applied at higher rates than those currently recommended for seed-placed MAP.

Source-separating urine for nutrient recovery may provide multiple benefits with regards to wastewater management, water conservation, and an impending phosphorus fertilizer shortage. Municipal wastewater systems are designed to treat the combination of urine, feces and graywater produced in household applications. Urine accounts for 1% of wastewater by volume, but provides 70-90% of nitrogen, 35-70% of phosphorus and 50% of the contaminants of emerging concern entering municipal wastewater treatment (Larsen and Gujer 1996). Research has shown managing source-separated urine for nutrient recovery is a more cost effective and less treatment intensive method than using traditional systems found in municipal wastewater plants. Phosphorus fertilizer shortages are projected as current sources diminish and become increasingly difficult to extract and refine. Phosphorus based-fertilizer recovery, in the form of 99.9% pure struvite (MgNH4PO4•6H2O), has been demonstrated successfully in full-scale sidestream treatment using dewatering liquor from anaerobically digested solids (centrate) processed through upflow fluidized bed reactor technologies (Britton et al. 2005). Prior research determined the influence of pH, magnesium to phosphorus (Mg:P) molar ratio, and age of urine on purity, pharmaceutical content and pathogen inclusion in struvite precipitated from source-separated urine. This is the first known example of an attempt to produce a commercially viable struvite product from source-separated urine in a fluidized bed reactor of a design that has been used successfully for struvite recovery in conventional wastewater applications. In order to assess the feasibility of nutrient recovery of phosphorus-based fertilizer recovery from source-separated urine, the first office-based urine separation and collection building was implemented in the U.S. Urine was collected, in a 400 gallon capacity underground sealed manhole, from HRSD's Main office building beginning in March 2015 from 5 men's waterless urinals and one women's separating toilet. Urine was collected from the manhole on a monthly basis in 275 and 330 gallon plastic totes stored at the HRSD Nansemond WWTP in Suffolk, VA. Collected urine was allowed to age while in storage to encourage the precipitation of excess multivalent cations that may interfere with struvite precipitation and inactivation of pathogens that may be present. An upflow fluidized bed reactor (UFBR) was used to recover struvite as a slow-release phosphorus based fertilizer (prill), the reactor was loaned to HRSD by the University of British Columbia. A magnesium solution was injected at the bottom of the reactor to facilitate precipitation along with the recycle urine stream and feed urine as shown. Prill production design for the reactor was 0.5 kilograms per day, but while using centrate to determine best operations practices, under loading the reactor to 0.25 kilograms per day maximized struvite recovery while minimizing particulate phosphorus loss. Urine was fed into the reactor for struvite removal based on phosphorus loading with recovery determined through removal of orthophosphate and harvesting of the struvite product. Consistency, size and quality of product including compactness, crystal structure, purity and presence of pharmaceuticals and pathogens were assessed. The UFBR was run for 50 days total; 10 days for a short term run to compare to operation of the reactor under the same conditions with centrate from anaerobically digested solids as a feed source, 30 days to assess consistency of operations over long term with respect to struvite recovery, and a 10 day test with urine spiked with pharmaceuticals and bacteriophage to evaluate inclusion of trace organics and viruses in recovered struvite. In total 2,040 gallons of urine were fed to the reactor targeting 12.45 kilograms of struvite recovery, a mass of 7.54 kilograms of prills were harvested from the reactor with 1.90 kilograms of phosphorus lost as particulate struvite (representing an recovery efficiency of 60.5%). Overall reactor operation using urine as a feed solution behaved similar to centrate, with slightly less removal of phosphorus. Urine-derived prills were lower in quality due to the lack of compact density seen in struvite recovered during full scale operation but had a visible orthombic pattern seen in precipitated struvite. Pharmaceuticals that were present in urine feed solution were found in struvite but at less than 1% of the feed mass. Some of this inclusion may have occurred due to porous characteristics of the small-scale UFBR recovered struvite rather than through actual inclusion in the mineral crystal itself. Spiking of caffeine and ibuprofen to high concentrations in the urine yielded no statistical difference from the non-spiked tote. Urine was non-detect for bacteriophage pathogen indicators leading to the assumption that no pathogens were present in urine-derived struvite. Spiking the urine with double-stranded DNA (T3) and single-stranded RNA (MS2) bacteriophage capable of infecting bacterial cells such as Escherichia coli yielded 10^6 plaque forming units per milliliter in source separated urine. Creating urine-derived struvite prills with minimal inclusion of pharmaceuticals using upflow fluidized bed technology is feasible on a small scale. Large-scale application, recovering 500 kilograms per day of struvite or more, will most likely create a higher quality prill with regards to compactness and diminished presence of pharmaceuticals and virus inclusion. Pretreatment of urine and post-treatment of prills with heat will aid in inactivation of virus that may be present. ' / Master of Science

No description available.