Dissertations / Theses: 'Struvite'

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Tarragó, Abella Elena. "Assessment of struvite and K-struvite recovery from digested manure." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/663399.

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Human population has had an impact on the natural phosphorus’ cycle, a limited resource, and the predictions show that this resource could be exhausted in 100-250 years. Therefore, the actions for the coming 10-25 years must be focus on the recovery of phosphorus, for example, from renewable sources such as manure. Thus, phosphorus recovery as struvite or K-struvite from manure is investigated, as the recovery of the essential nutrients is considered to be a significant breakthrough for assuring long-term and economical phosphorus supply, while recovering a valuable slow-release fertilizer. Therefore, this PhD thesis proves the feasibility of recovering nutrients from manure, a complex matrix with high concentration of solids. Furthermore, aims to bring innovation and insights on the sustainable recovery of fertilizers (i.e. ammonium and/or potassium struvite) from swine manure
Els humans han tingut un impacte en el cicle natural del fòsfor, un recurs limitat, i són vàries les prediccions sobre la possible extinció d’aquest en 100-250 anys. Per tant, les accions a dur a terme durant els propers 10-25 anys haurien d’anar enfocades a la recuperació d’aquest, per exemple, a partir de fonts renovables com els purins. Així doncs, es planteja la recuperació de fòsfor en forma d’estruvita o K-estruvita a partir de purins, ja que la recuperació de nutrients essencials (nitrogen, fòsfor, potassi) es considera un avanç important i essencial per assegurar el subministrament de fòsfor econòmicament a llarg termini, al mateix temps que s’obté un fertilitzant d’alliberació lenta. En aquesta tesi doctoral s’ha demostrat la viabilitat de la recuperació de nutrients a partir de purins, una matriu complexa amb una elevada concentració de sòlids. També pretén aportar innovacions i reflexions sobre la recuperació sostenible de fertilitzants (estruvita i/o K-estruvita) a partir de purins

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2

Ezquerro, Ander. "Struvite Precipitation and Biological Dissolutions." Thesis, KTH, Mark- och vattenteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31451.

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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.

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Le, Corre Kristell S. "Understanding struvite crystallisation and recovery." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/1434.

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Struvite crystallisation from wastewater effluents is seen as an alternative to traditional biological and chemical phosphorus removal processes used widely in the wastewater treatment industry. It presents the advantage of not only removing phosphorus but also generating a compound that could be reused as a fertiliser. However the application of struvite crystallisation processes at full scale is not widespread due to the unknown economical value of the process and the product, the need of pH control, the necessity of long operational times to ensure quality of the product and the formation of crystal fines. Preliminary crystallisation experiments were carried out at laboratory scale to provide a better understanding of nucleation and growth processes, and identify how basic parameters such as pH, mixing energy, water chemistry or presence of foreign ions affected struvite crystallisation. Particular attention was paid to the quality (i.e. size, shape and purity) of the crystal formed. The results revealed that the presence of calcium ions in solution could alter struvite purity and even inhibit its formation. pH was also identified as a parameter of major impact on struvite crystal quality. Indeed, pH could either influence struvite purity or affect size of crystals formed. Further investigations in a purposely built reactor also revealed that if struvite crystallisation is relatively simple to achieve, the control of struvite quality and more particularly crystal size is complex. Results at pilot scale showed that reactor operation and struvite surface charge could be a limitation to its agglomerative properties, hence to the formation of larger crystals. To optimise struvite crystallisation and limit the problem of fines formation the present study has investigated two possible solutions: struvite fines recovery by coagulation or struvite crystallisation on seed materials. Struvite coagulation proved to be an efficient solution to remove and recover struvite fines rapidly through floc formation. Of the coagulant tested, polyDADMAC was the most effective resulting in the formation of flocs 10 times bigger than the initial size of crystals. With regards to crystallisation on seed materials, the results revealed that success of struvite attachment onto seeds in short contact times was only efficient when mixing energy in the reactor was limited. In that sense, the submersion of a metallic system in the reactor allowed excellent phosphorus removal and rapid struvite recovery in only 2 hours of operation.

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Farhana, Sharmeen. "Thermal decomposition of struvite : a novel approach to recover ammonia from wastewater using struvite decomposition products." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54180.

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Ammonia recovery technology, utilizing newberyite (MgHPO₄.3H₂O) as a struvite (MgNH₄PO₄.6H₂O) decomposition product, is gaining interest as usage of newberyite can significantly reduce the cost of commercial reagents, by providing readily available magnesium and phosphate for struvite reformation. In this study, the efficiency of ammonia removal from struvite, and a transformation process of struvite to newberyite, were investigated through performing oven dry, bench-scale and pilot-scale experiments. In the oven dry experiments, the structural and compositional changes of synthetic struvite, upon decomposition, were evaluated. Around 60-70% ammonia removal efficiency was achieved through struvite thermal decomposition above 60º±0.5ºC, with up to 71.1ºC with prolonged heating. The 2D amorphous layered structure, present in the decomposed solid phase, entrapped around 30-40% residual ammonia between the layers of magnesium and phosphate, inhibiting further ammonia removal. Subsequently, bench-scale experiments were conducted based on the hypothesis that humid air can prevent the formation of a layered structure including dittmarite (MgNH₄PO₄.H₂O) and an amorphous 2D layered structure. Struvite pellets of different sources and sizes were heated in a fluidized bed reactor in the presence of hot air and steam. Introduction of steam resulted in complete transformation of struvite pellets (<1mm) into newberyite at 80ºC, 95% relative humidity and 2 hours of heating. Finally, pilot-scale experiments were carried out to further optimize the operating conditions for industrial application. The smaller and softer pellets (size <1mm, hardness 300-500 g) were the best suited for struvite-to-newberyite conversion. The process was optimized further by narrowing down the relative humidity from 95% to 85% and reducing the heating duration from 2 to 1.5 hours. The operating cost of the pilot-scale process was estimated, which can be reduced through recycling the heat and moist air over the cycle. The number of cycles for which the decomposed product can be effectively reused depends on the required overall N-recovery efficiency, as well as the performance of the struvite recrystallization stage. The greatest advantage of the proposed technology, over other recovery methods, is that the operating costs can be turned into revenue by utilizing the recovered product as fertilizer or energy source.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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Bennett, Aline Miriam. "Potential for potassium recovery as K-struvite." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54296.

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Crystallization of NH₄-struvite (MgNH₄PO4:6H₂O) pellets has proven to be a successful method of recovering nitrogen and phosphorus from wastewaters. Thus far, little work has been done on potassium recovery since it is not considered a water pollutant, nor do we face potassium shortages. However, potassium is an essential plant macronutrient and we are seeing worldwide imbalances in nutrient and fertilizer use, as well as a need for a slow release potassium fertilizer. Development of a full complement NPK fertilizer with NH₄-struvite and K-struvite components may have great potential. Given this, research into potassium recovery through crystallization of K-struvite (MgKPO₄: 6H₂O) is relevant and complements previous work done with NH₄-struvite. The goals of this research were to develop fundamental understanding of K-struvite formation as the first step to recovering potassium, and eventually produce a full complement NPK slow-release fertilizer from wastewaters. This required the determination of new solubility product values for K-struvite at different temperatures, followed by bench-scale experiments to assess K-struvite synthesis under various solution conditions. A model to simulate each batch experiment and to predict optimal supersaturation conditions for K-struvite precipitation was developed using PHREEQC, aqueous equilibrium modelling software. Finally, initial experiments in the UBC fluidized bed reactor (UBC-FBR) were undertaken to assess the pelletization potential of K-struvite. New solubility product values for K-struvite indicate that it is less soluble than previously reported, and the values determined at 10, 25 and 35°C fit the Van’t Hoff model. Optimal Mg:K:P molar ratio for synthesis of pure K-struvite was found to be approximately 3:50:1 in a wastewater matrix with pH 8, P-PO₄ concentration of 8 mM and a Mg:P ratio of 3:1. These concentrations were used in the UBC-FBR to assess the pelletization potential of K-struvite. These initial reactor runs were inconclusive due to an inability to stabilize the reactor without seeding. It would be recommended to seed the reactor during start-up in order to be able to compare process performance with the NH₄-struvite crystallization process in the UBC-FBR. This study showed that formation of pure K-struvite is possible given the right supersaturation conditions in solution, requiring high potassium concentrations.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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6

Zhang, Chi. "Struvite Precipitation of Ammonia from Landfill Leachate." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34492.

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The application of struvite (magnesium ammonium phosphate,!MgNH&PO& ∙ 6H+O) precipitation and its recycling use for the purpose of ammonia removal from both synthetic solutions and landfill leachate were investigated in this study. The results demonstrated that chemical precipitation by struvite formation is efficient for ammonia removal from aqueous solutions. In addition, by recycling the thermal residue of struvite, continuously removing ammonia can technically be achieved. In the struvite precipitation, ammonia removal significantly depended on the pH and chemical molar ratios of NH& ,:!Mg+,:!PO& ./. For synthetic solution (TAN=1,000 mg/L), remarkable TAN removal efficiency of over 98% has been reported when the molar ratio of NH& ,:!Mg+,:!PO& ./ equals 1.0:1.2:1.2, 1.0:1.3:1.3, 1.0:1.3:1.4 and 1.0:1.5:1.5 at optimum pH 9. The optimum combinations of reagents applied in landfill leachate (TAN=1,878 mg/L) were!NH& ,:!Mg+,:!PO& ./ =1.0:1.3:1.3, 1.0:1.4:1.3, 1.0:1.5:1.4 and 1.0:1.5:1.5 at optimum pH 9.5, all of which displayed excellent TAN removal efficiencies of over 99%. Response surface method (RSM) helped to analyze the data and optimize the results. The struvite pyrolysate provided best performance of removing ammonia in both simulated wastewater and landfill leachate at a dosage of 60 g/L, when struvite was previously heated at 105 􀀁 by oven for 2.5 h. In the recycling phase, the struvite pyrolysate resulting from NaOH-mediated pyrolysis was more effective at continuously treating ammonia synthetic solution than was direct heating, with an initial mode of 87.4% at the beginning to 75.1% in the fifth round and direct heating of struvite from 80.9% in the first cycle and 60.6% in the final cycle. The struvite pyrolysate formed by NaOH-mediated pyrolysis performed with greater ability to continuously eliminate ammonia from landfill leachate (97.2% removal at the beginning and 72.3% in the fifth round), than did directly heated struvite (98.4% in the first cycle and 81.3% in the final cycle). Additionally, microwave irradiation could also dissociate struvite, which subsequently demonstrated moderate TAN removal in recycling phases.

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Ackerman, Joe. "Reclaiming phosphorus as struvite from hog manure." Ackerman, J. N., and N. Cicek. 2011. Phosphorus removal and recovery from hog lagoon supernatant using a gravity-settled batch reactor and increased pH. Biological Engineering Transactions 4(4): 207-218, 2011. http://hdl.handle.net/1993/14914.

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The over application of manure phosphorus (P) to farmlands can lead to P build up in the soil and eventual runoff to surface waters causing eutrophication. Reducing P in manure by precipitation of struvite enables P capture and reuse as a fertilizer in the agricultural supply stream. Struvite precipitation is dictated by levels of soluble P which can be highly variable according to manure treatment and management. This research studied P forms in liquid pig manure, ways of increasing P-PO4 levels in manure from strategic storage conditions, novel struvite reactors, and the effectiveness of struvite as a fertilizer. Studies that monitored soluble nutrients during manure storage revealed that P-PO4 concentration was sensitive to pH and time. Anaerobic fermentation of manure increased P-PO4 by 2.5 fold with 12 days of storage, provided the buffering by alkalinity was low. Two different struvite reactors were operated, a batch-type system for processing lagoon supernatant and an upflow air sparged reactor that used supernatant from a rotary press solids separator. They achieved 75% and 31% total P removal, respectively. The upflow reactor operated without chemical addition at pH 6.8 to produce high purity struvite free of calcium phosphates. Costs of both reactors were comparable ($0.0139 and $0.0167/kg live pig wt) and similar to other pilot struvite reactors. Manure derived struvite was compared with pure struvite and commercial fertilizer for agronomic value in canola production. Results of a greenhouse pot experiment showed no significant difference between the two struvites despite impurities in the manure precipitate.

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Sellaturay, S. V. "Physico-chemical basis for struvite stone formation." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1336882/.

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Introduction: Struvite stones (magnesium ammonium phosphate) account for 10-15% of renal stones and can grow rapidly forming staghorn calculi. With limited medical therapies available and surgery the mainstay of treatment, an understanding of the physico-chemical conditions causing struvite crystallization allows development of strategies to prevent their formation. At present, very little is known about the physico-chemical conditions that result in struvite crystallisation. This lack of understanding has two bases: i) the particular ionised concentrations of the reactants (e.g. Mg2+, NH4+, and phosphate) in the urine are unknown; ii) the prevailing chemical conditions that would modulate crystallisation are also unclear (e.g. pH, osmolality, other urinary constituents).Recent advances in the development of ion-selective electrodes allows accurate determination of urinary constituents in small (<1ml) undiluted samples. Methods: We have furthered developed an NH4+-ion selective electrode and magnesium ion-selective electrode to measure the urinary concentrations of each to aid our understanding of struvite deposition. [NH4+] and [Mg2+] were measured using plastic dip cast ion-selective electrodes dispersed in suitable plasticisers, using nonactin for NH4+ and several different neutral ligands for Mg2+. Data were validated against standardised and developing methodology, including colour spectrophotometry and computational algorithms. Urine samples were also subjected to analysis using clinical biochemical techniques. Results: We characterised an NH4+-ion selective electrode and made the first measurements of [NH4+] in undiluted urine samples, in normal subjects and those with stone disease. This technique was validated using colour spectrophotometry and then the technique was used to validate a computational algorithm. We have developed and characterised the Mg2+-ion-selective electrode but Ca2+ caused significant interference. Conclusions: Direct measurement of the urinary [NH4+] has been achieved for the first time with a value of about 25mM. This exciting new technique may now provide clinicians with an important point-of-care investigative tool in diagnosing and monitoring struvite calculogenesis.

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Doyle, J. D. "Struvite formation and control in wastewater treatment." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/11427.

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Struvite causes maintenance, and operational problems due to fouling in wastewater and sludge treatment systems. Struvite formation was initially investigated using a series of jar tests on real and synthetic sludge liquors. A computer model predicting struvite precipitation potential was compared to the results generated. Struvite formation was found to be closely linked to pH with increasing pH resulting in decreasing struvite solubility. Further studies analysed the relationship between a solutions' supersaturation ratio, material and the scaling rate. Tests were undertaken at 3 supersaturation ratios with 3 different materials: stainless steel, Teflon and acrylic. Acrylic and Teflon coupons were scientifically roughened to show the influence that surface roughness has on a materials' scaling propensity. The control of struvite precipitation was investigated using a range of chemical inhibitors and chelating agents. Experiments using the same materials used previously were performed with a range of scale inhibitors and chelating agents. The scale inhibitors did not prevent struvite from forming, with only one product, Polystabilis, showing a reduction in the mass of scale formed on the impellers. Of the chelating agents tested, EDTA was the most effective even in alkaline conditions and was shown to have the ability to re-dissolve struvite previously formed on materials.

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Ramaru, Rendani. "Phosphate precipitation as struvite from municipality wastewater." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5412.

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Tshwane Municipality produces approximately 4Ml/day of dewatering liquors arising from municipal sludge from a wastewater treatment plant. The sludge being dewatered is a combination of an anaerobically digested primary sludge and an undigested waste activated sludge. High phosphate and nitrogen are released into water during the anaerobic treatment process. High concentrations of these nutrients in the wastewater lead to eutrophication, which is a major environmental problem (Doyle et al., 2000). In view of the above problem, the aim of this project was to investigate the feasibility of precipitating phosphate in the form of struvite (MgNH4PO4.6H2O) from the Tshwane Municipality dewatering liquors and consequently recovering it as a valuable and marketable product. The project was investigated in three sequential stages consisting of: 1. An aqueous thermodynamic modelling study using OLI Systems Inc. Stream Analyser Version 2.0.57 to determine the precipitation conditions required for the removal of phosphates in the dewatering liquor. 2. Bench'scale laboratory experiments to investigate the feasibility of phosphate precipitation as struvite under different pH conditions, Mg: P molar ratios and Ca:P molar ratios. 3. Fluidised bed experiments to establish the characteristics of phosphate removal at varying levels of supersaturation. The results suggest that the pH of the system has a significant effect on phosphate removal due to its influence on the availability of PO4 3, NH4 + and Mg2+. According to the thermodynamic modelling results, phosphates are removed as Ca3(PO4)2 and Mg3(PO4)2.8H2O. Removal of phosphate as Mg3(PO4)2.8H2O starts at a pH above 7 with the maximum removal achieved at pH 10. Thereafter, phosphate removal as Mg3(PO4)3.8H2O drops to zero due to Mg(OH)2 precipitation being favoured at the higher pH values. Thermodynamic modelling shows that a high NH4 +:P molar ratio is required to induce struvite precipitation. For sample C1, which had a PO4 P and an NH4 + concentrations of 145mg/L and 65mg/L respectively, the bench scale experiments showed that approximately 30%, 80% and 92% of the phosphate was removed at pH 8, pH 9 and pH 10, respectively. The NH4 +:P molar ratio in ii the precipitate decreased to zero at pH 10 because NH3 formation is favoured at this pH. The XRD analysis showed that the precipitate was Mg3(PO)2.22H2O. On the other hand, it was shown that phosphate was removed as struvite, for sample C2, which had PO4 P and NH4 + concentrations of 93mg/L and 57 mg/L, respectively. The NH4 +: P molar ratio of sample C1 was 0.99 while the NH4 +: P molar ratio of sample C2 was 1.35. However, it was shown that phosphate was removed as Mg3(PO)2.22H2O under pH 10 conditions. Thus, high NH4 +: P molar ratios (i.e. 1.35) in the waste water favours struvite precipitation with the optimum pH level for phosphate removal as struvite being pH 9. Bench scale experiments showed that, amorphous calcium phosphate precipitation is favoured over struvite precipitation at high Ca:P molar ratios. At a Ca:P molar ratio of 0.85:1, it was shown that no struvite was formed. The bench scale experiments showed that the phosphate conversion increased at high Mg:P molar ratios. However, the effect of increasing Mg:P molar ratio on phosphate conversion was significant at pH 9. While at pH 10 there was insignificant increase of phosphate conversion as Mg:P molar ratio was increased probably due to formation of MgOH+ ions at high pH levels. It was shown that high Mg:P molar ratios slightly limits calcium conversion. The calcium conversion was reduced by approximately 10% when Mg: P was increased from 1:1 to 1.4:1 for systems operated at pH 9 and pH 10 conditions. The supersaturation ratio of amorphous calcium phosphate is 104 greater than the magnesium compounds (i.e. struvite and Mg3(PO4)2.22H2O) supersaturation ratio as a result the effect of increasing Mg:P on calcium conversion was relatively very small. The fluidized bed reactor experiments showed that high Mg:P molar ratios increased the phosphate removal as a result of the increased free Mg2+ concentration. However, the high Mg:P molar ratios resulted in an increased supersaturation which led to the formation of many fine particles. There was an increase in overall conversion from 68% to 83 % when the Mg:P molar ratio was increased from 1:1 to 1.2:1. On the other hand, the removal decreased from 45% to 38% when the Mg:P molar ratio was increased from 1:1 to 1.2:1. Moreover, struvite with high purity was produced at a high Mg:P molar ratios (i.e. Mg:P =1.2). Fluidized bed reactor experiments showed that as the recycle ratio was increased the PO4 P conversion also increased. Thus, large amount of struvite particles were recycled to the fluidized bed reactor. As a result, struvite particles provide favourable nucleation sites for struvite precipitation hence high conversion were achieved at higher recycle ratio.

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Doyle, James David. "Struvite formation and control in wastewater treatment." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/11427.

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Struvite causes maintenance, and operational problems due to fouling in wastewater and sludge treatment systems. Struvite formation was initially investigated using a series of jar tests on real and synthetic sludge liquors. A computer model predicting struvite precipitation potential was compared to the results generated. Struvite formation was found to be closely linked to pH with increasing pH resulting in decreasing struvite solubility. Further studies analysed the relationship between a solutions' supersaturation ratio, material and the scaling rate. Tests were undertaken at 3 supersaturation ratios with 3 different materials: stainless steel, Teflon and acrylic. Acrylic and Teflon coupons were scientifically roughened to show the influence that surface roughness has on a materials' scaling propensity. The control of struvite precipitation was investigated using a range of chemical inhibitors and chelating agents. Experiments using the same materials used previously were performed with a range of scale inhibitors and chelating agents. The scale inhibitors did not prevent struvite from forming, with only one product, Polystabilis, showing a reduction in the mass of scale formed on the impellers. Of the chelating agents tested, EDTA was the most effective even in alkaline conditions and was shown to have the ability to re-dissolve struvite previously formed on materials.

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Ariyanto, Eko. "Crystallisation and dissolution studies of struvite in aqueous solutions." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/659.

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Struvite (MgNH4PO4.6H2O) is present in municipal wastewater treatment plants. It causes scaling in the plant but recent studies showed that it could be recovered as an alternative form of fertilizer. This study was conducted in order to get a better understanding of the crystallisation of struvite. The results may be used for better design and operation of wastewater treatment plants with production of struvite as a useful by-product.

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Qu, Xiaocao. "Bench-scale two-dimensional fluidized bed hydrodynamics and struvite growth studies." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/382.

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A bench-scale, two-dimensional multi-compartmentalized fluidized reactor was designed and studies of hydrodynamic behavior of fluidization of struvite pellets were performed. Also size growth distribution tests were analyzed qualitatively. The study validated a previously-proposed theory, concerning the relationship between dynamic pressure drop and upflow velocity as well the experimental protocol to determine the minimum fluidization velocity. Findings indicated that the mixture of two-sized particles would behave rather independently of each other, before the bed expansion. It was suggested that bed height measurement could be another promising method to pinpoint minimum fluidization velocity as there is a sharp bed surface "waking episode" during the process of a packed bed being gradually fluidized. Bed expansion equations for the prediction of void fraction as a function of superficial upflow velocity or vice versa, have been established for 4 groups of monosize particles, as well as two mixtures of two-sized particles. The equation constants did not agree well with previously established ones. The two layers of segregated mixture bed had congruent linear relationships between the logarithmic void fraction and logarithmic upflow velocity. It was found that a mixture does not always go through segregation, but only when the size difference is large enough. Size growth distribution tests were performed under different hydrodynamic configurations as well as seeding conditions. Conclusions can be made that a bed with uniformly- distributed particle void fractions and higher mixing energy input (upflow velocity), normally has better performance of struvite growth in size.

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Novotny, Chad. "Ammonia removal and recovery using heated struvite as an adsorbent." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/31595.

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The removal and recovery of aqueous ammonia from BNR plant centrate or supernatant is an important research area. Stringent ammonia discharge requirements must be met to avoid fish toxicity in the receiving waters. Completely removing ammonia from the process reduces the load recycled back to the head of the plant and minimizes operational problems associated with high return loads. The controlled recovery of phosphate and ammonia into struvite with a dedicated fluidized bed crystallizer has led to the production of commercially valuable struvite pellets for the fertilizer industry. However, excess ammonia remains after struvite crystallization. The purpose of this research was to initiate the development of a nitrogen removal technology. This was achieved using the isothermal decomposition of struvite to remove ammonia. The decomposed pellets were subsequently placed into an ammonium solution for removal of excess aqueous ammonium. Struvite was shown to decompose into a mixture of magnesium phosphates and struvite. Satisfactory decomposition was achieved with a minimum of 100°C for 30 minutes. Ammonium removal reached up to 99% for a solution pH 8. Effective ammonia-N removal required a minimum reaction duration of between 15-30 minutes with a 66.7g/L dose. Struvite heated at higher temperatures worked as a better substrate to remove aqueous ammonia-N. Molar ratio comparisons show that the ammonia removed from solution is likely incorporated into newly formed fine struvite, rather than being incorporated into the heated struvite. This provides evidence in favour of a dissolution-reformation mechanism, whereby heated struvite acts a source of magnesium and phosphate. Heated struvite is more soluble than unheated struvite, because water of hydration and ammonia are removed from the pellet. Mass balances were reasonable but were complicated by natural adsorption of atmospheric water onto heated pellets. The economic viability of this technology may be unfavourable. A trade off exists between high ammonium removal and dissolution of pellets, which are worth up to $3000 per tonne in the United States. The total daily cost to remove nitrogen using this technology is estimated to be about 15 times greater than using side stream nitrification.

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Gagnon, Alexandria Augusta. "Struvite Recovery From Source-Separated Urine Utilizing Fluidized Bed Technology." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/72886.

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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

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Shen, Yanwen. "Investigating pretreatment methods for struvite precipitation in liquid dairy manure." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/43521.

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Phosphorus (P) recovery and re-use is very important today for sustainable nutrient cycling and water quality protection due to the declining global P reserves and increasingly stringent wastewater treatment regulations. P recovery as struvite (MgNH4PO4â ¢6H2O) is a promising technology because it can be used as a slow-release fertilizer. The objective of this study was to investigate different pretreatment methods to enhance struvite precipitation in dairy manure. Generally there are two challenges that need to be overcome to precipitate struvite in liquid dairy manure. The first is the relatively high calcium (Ca) concentration. The present study investigated the effectiveness of two calcium binding reagents to reduce the calcium inhibitory effects to enhance the struvite precipitation. A chemical equilibrium model (Visual MINTEQ 2.60) was used to determine the pH to acidify manure and to precipitate struvite. Then, bench-scale experiments were conducted to validate the model results using synthetic and untreated manure. First, the manure was acidified (pH 4.5) to liberate the particulate-bounded Mg2+, Ca2+ and inorganic P. Second, EDTA and/or oxalate compounds were added to the manure. Third, pH was increased to 7.5 for struvite precipitation from the liquid filtrate. Results showed that struvite-containing crystals were obtained from the samples treated with calcium removal compounds, with a total suspended solids (TSS) concentration less than 4,000 mg/L. The second challenge is the low dissolved reactive P (DRP, i.e. PO4-P) to total P (TP) ratio. This study investigated different pretreatment methods for P release to enhance struvite precipitation in liquid dairy manure: enhanced biological phosphorus removal (EBPR), microwave heating (MW) and anaerobic digestion (AD). All of the pretreatment methods resulted in P release but struvite crystals were observed only in precipitates obtained in manure pretreated with MW+H2SO4 acidification. Without oxalic acid to reduce the Ca2+ effects, all the other pretreatment methods were not effective in enhancing struvite precipitation in liquid dairy manure. Hardly any struvite or crystalline-like solids were found in the non-centrifuged samples, regardless of any pretreatment, indicating the effects of suspended solids and organic matter on struvite precipitation. A partial economic analysis was conducted to assess the chemical costs of P recovery from liquid dairy manure with different pretreatment methods; P recovery amounts as struvite were modeled by Visual Minteq 2.61.Three pretreatment conditions (untreated manure + oxalic acid, MW + H2SO4 acidification, and AD) were selected based on the precipitation results. MW + H2SO4 acidification produced the highest struvite quantities among the pretreatment methods to enhance struvite recovery, also with the lowest chemical addition costs.
Master of Science

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17

Moragaspitiya, Chathurani. "Nutrient recovery as struvite from conventional activated sludge treatment plants." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/136415/1/Chathurani_Moragaspitiya_Thesis.pdf.

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The main aim of the research work in this thesis is to study the nutrient recovery from conventional wastewater (sewage) treatment plant and then to reuse the recovered nutrients for immobilization of heavy metals in contaminated soil. The research findings confirm the potential of reducing pollution loads of concentrated wastewater by recovering nutrients, which can be used as a fertilizer as well as a soil amendment for heavy metal immobilization. The research outcomes in this thesis should be of great engineering significance to the wastewater industry and environment sustainability.

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Kajsa, Ignberg. "Struvit i Skövde biogasanläggning : En studie av struvitpåväxt i rör och alternativa lösningar för att minska problemet och dess uppkomst." Thesis, Mittuniversitetet, Avdelningen för ekoteknik och hållbart byggande, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-25186.

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Målet med denna undersökning har varit att finna metoder för rening av struvitpåväxt i rör på Skövde biogasanläggning samt metoder för att undvika uppkomst av struvit. Detta för att man på anläggningen ska kunna öka verkningsgraden och fungera mer resursoptimerat för att på så sätt komma närmare en hållbar samhällsutveckling. Struvit (magnesiumammoniumfosfat hexahydrat) är ett vitt hårt mineral som vanligtvis förekommer i rör, värmeväxlare, pumpar och centrifuger på vattenreningsanläggningar och efter rötningsprocess på biogasanläggningar. Struvit fäller ut som en följd av bland annat pH, temperatur, koncentration och övermättnad. Även rörmaterial kan ha en påverkan på struvitfällning. Undersökningen har genomförts med hjälp av studiebesök samt analys av biogödsel och struvit på Skövde biogasanläggning. Detta för att ta fram den mängd struvit som kan fälla och vart på anläggningen detta sker. En enklare benchmarking har genomförts som har visat att struvitfällning på biogasanläggningar främst uppstår i värmeväxlare och att påväxten där är temperaturberoende. Material och kemikalier har undersökts för att ta fram metoder för rening och hindrande av uppkomst av struvit. Undersökningen har visat på att struvit främst uppkommer i värmeväxlaren och i rörkrökar på anläggningen och att detta är beroende av de pH, övermättnad, temperaturer och höga koncentrationer av fosfor, magnesium och ammonium som finns. Utifrån studien har en teori skapats om att mineralet först uppkommer i kammaren mellan rötkammare och mellantank. Undersökningen visar vidare på att de metoder som är mest effektiva för borttagning av påväxt struvit är att hacka loss mineralen alternativt byta ut rören. För att hindra att påväxt på rör sker rekommenderas att en kombination av metoder genomförs, vilka minskar energianvändningen på anläggningen och hindrar stopp i biogasproduktionen. Kemikalier bör användas om kristallbildning helt ska hindras. Dessa bör tillsättas i nämnda kammare. Till detta bör planerade underhåll ske för att minimera redan påväxt struvit. De rör som byts på anläggningen bör i främsta hand bytas mot plastmaterial. På så sätt kan anläggningen fungera mer resurseffektivt och onödig miljöpåverkan undviks. I studien har endast en grov kostnadsanalys kunnat genomföras. För att vidare understödja ovanstående metod rekommenderas därför en djupare ekonomisk analys genomföras. Denna bör även innefatta studier av kemikaliedos samt undersökning av kontrollplatser för planerade underhåll.
The goal with the study has been to find methods for cleaning and prevention of struvite at Skövde biogasanläggning (biogas plant). This to increase the efficiency and resource optimize the biogas plant and in that way get closer to a sustainable development of the society. Struvite (magnesiumammoniumphosphate hexahydrate) is a white, harsh mineral that commonly occurs in pipes, heat exchangers, pumps, and centrifuges at wastewater plants and after digestion processes at biogas plants. Struvite precipitates as a result of pH, temperatures, concentrations and supersaturation. Pipe material can also contribute. The study has been conducted through study visits and analyses of digestate and struvite at Skövde biogasanläggning to find the amount of struvite that can precipitate and where at the plant this happens. A simple benchmarking has been conducted, which shows that struvite precipitation at biogas plants mainly occurs in heat exchangers and that the fouling is temperature dependent. Materials and chemicals have been studied to find methods for cleaning and prevention of struvite. The study has shown that struvite mainly occurs in the heat exchanger and in pipe bends at the biogas plant and that it is dependent of the pH, supersaturation, temperature and high concentrations of phosphorous, magnesium and ammonium. A theory has been made from the study that the mineral first appears in the chamber between the digesters and heat storage tank. The study further shows that the most effective methods to clean fouling of struvite is to by hand chip the mineral alternatively replace the pipes. To prevent fouling of pipes a combination of methods is recommended, which minimizes the energy usage at the plant and prevent stops in the biogas production. Chemicals should be used if crystallization is to be completely stopped. The chemicals should be added in the above- mentioned chamber. Also planned maintenance should be conducted to minimize fouling. The pipes that are to be replaced should be replaced with pipes made of plastic materials. By doing this the resource efficiency increases and unnecessary environmental impact of the plant is avoided. The study has only included a rough cost analysis. To further support the above- mentioned methods a deeper economic analysis is recommended, which should include a study of chemical dosage and inspection sites for planned maintenance.

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Eghtesad, Masoumeh. "Optimization of magnesium removal from hydrometallurgical leach liquors by struvite formation." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58789.

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Nickel is a vital metal which occurs in two types of ore: laterites and sulfides. Historically sulfide ores have been the primary source of nickel however due to their limited resources and the vast occurrence of laterites, laterite processing has gained a great deal of attention. Nickel in laterite ores is accompanied by impurities such as magnesium and iron, due to their similarity in ionic radii and their capability in replacing one another in crystal lattices. Magnesium compounds are highly soluble, therefore, magnesium impurity in nickel processing leads to the production of non-recyclable process water which results in high water consumption and negative environmental impact due to the wastewater being discarded to the environment. An approach has been derived at the University of British Columbia which involves the removal of magnesium compounds from nickel plant wastewater streams as struvite. Struvite, MgNH₄PO₄·6H₂O, is a valuable fertilizer which provides three important nutrients of magnesium, phosphorus and nitrogen to plants. This study confirms the ability of the proposed flowsheet to successfully remove magnesium as struvite from nickel laterite plants from both aspects of the magnesium removal efficiency and the produced struvite purity; with the experiments conducted at the base conditions having magnesium removal efficiency of above 95 percent and the produced struvite purity being above 97 percent. This study focuses on the optimal conditions leading to the maximum magnesium removal and therefore struvite precipitation. Struvite precipitation is affected by many parameters. The most influential factors affecting struvite crystallization are mixing intensity, seeding and the seeding technique, pH, temperature, crystal retention time, magnesium to phosphate ratio, supersaturation level and the impurities present in the system. This study verifies that each of these parameters affect struvite precipitation differently. For instance, variations in supersaturation level and pH have greater effect on struvite precipitation then variations in temperature and mixing intensity. Additionally, this study confirms that the optimum condition for struvite precipitation is the same as the existing conditions of the effluent solution such as ambient temperature and pH; therefore, no further adjustment is required; however, solution seeding with struvite powder does improve the magnesium removal efficiency.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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20

Shepherd, Timothy Allen. "Concentration and extraction of phosphorus from swine manure slurries as struvite." [Ames, Iowa : Iowa State University], 2007.

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21

Wang, Xuan. "Nitrogen conservation by struvite formation during composting process with food wastes." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/201.

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Food waste as a dominant fraction of municipal solid waste was in most of cases buried in landfills creating a burden on big cities with large populations such as Hong Kong. Composting provided an environmentally viable technology to divert food waste to resource utilization for the production of valuable organic fertilizer. The main problem associated with food waste composting was the intensive acidification prior the commencement of the composting process, which is commonly adjusted by the addition of alkaline materials such as lime. However, more than 50% of the initial nitrogen will be lost as ammonia, which not just reduces the nutrient value of the compost but also leads to serious odour generation. Therefore the objective of this study was to develop means to reduce the nitrogen loss through struvite formation. The first experiment of this research investigated the feasibility of controlling the nitrogen loss through struvite formation during food waste composting. Struvite forms when magnesium (Mg), phosphorus (P) and nitrogen (N) salts exist in equimolar ratio at a slightly alkaline pH. Thus to fix the ammonia, MgO and K2HPO4 were added to food waste indifferent molar ratios (P1, 0.05M/kg MgO and 0.05M/kg K2HPO4; P2, 0.05M/kg MgO and 0.1M/kg K2HPO4) to induce struvite formation that can fix the compost-borne ammonia during composting. The pH of the composting mass of P1 was below 5 for more than one. However, the pH of P2 was controlled in a narrow range from 6.8 to 8.7. This slightly alkaline pH ensured a good microbial activity and improved the degradation rate as well as the precipitation of struvite. In treatment P2, the formation of struvite effectively reduced the nitrogen loss from 40.8% to 23.3% when compared to treatment with lime amendment. However, electrical conductivity (EC) of the compost increased to 6.4 mS/cm due to the addition of Mg and P salts. High salinity of the compost retarded seed germination which required further investigation to reduce the salinity while maintaining good nitrogen removal. To overcome this issue, lime as the more effective alkaline amendment, was supplemented in different concentrations along with struvite salts (to P1 treatment having less Mg salt that could reduce the salinity) to alleviate the low pH and struvite formation. The pH of the composting masses were effectively increased with increasing lime dosages and 2.25% lime was sufficient to maintain the pH in alkaline condition that significantly improved the degradation of active organic compounds resulting in increased dissolved organic carbon (DOC) and soluble organic nitrogen (SON) contents. With 2.25% lime and struvite salts, ammonia emission was significantly reduced from 44.3 to 27.4% through struvite formation compared with lime alone treatment. Furthermore, the EC were also decreased from 5.21to 3.40 mS/cm when lime amendment rate increased from 0.75% to 3%. However, the ammonia emission increased with an increase in lime dosage. Interfering ions such as calcium and potassium were reported to affect the struvite formation and pH control. Therefore, in the subsequent experiment, the influence of different types of P salts was investigated to reduce the salinity as well as N loss. When K2HPO4, Na2HPO4 and H3PO4 were used as the supplementary P salts, there were no significant differences on nitrogen conservation. In addition, the results indicated that K+ and Na+ were attached on the surface of struvite rather than constituted the crystal structure. Compared with other P salts, the presence of K+ in K2HPO4 also made a contribution to total nutrient content that benefited the final product. When CaO was gradually substituted with MgO as pH amendment, ammonia emission was significantly reduced implying that Ca2+ ions would influence the struvite formation, either by competing for phosphate ions or by interfering with the crystallization. However, this negative effect could be ignored when the Ca2+/Mg2+ ratio was below 1:2. Considering the cost of MgO, supplementation of Ca2+/Mg2+ ratio at 1:2 (0.15M CaO and 0.3M MgO) with 0.05M K2HPO4 was identified as the optimum conditions (Treatment M0.3) that effectively reduced the nitrogen loss to 28% in contrast to 46% with lime addition. The significant reduction of ammonia emission through struvite formation was observed with the optimum condition that the odour unit (OU) of ammonia emission was reduced to 1.8×104 when compared with lime treatment (3.0×104) indicating a significant reduction of OIMAX (maximum odour index). Meanwhile, the well-controlled pH of this technology ensured the effective decomposition of organic matter that significantly reduced the emission of volatile fatty acids (VFAs) also. The population of total bacteria was also improved due to the addition of phosphate salts. The total nutrient content of struvite composts of treatment with optimum condition (M0.3) was 4.14% (1.5% N, 0.44% P and 2.2% K) that was higher than normal lime treated compost 2.92% (1.3% N, 0.34% P and 1.28% K). In pot experiment, soil was amended with composts at 0, 2.5%, 5% or 10% (w/w dry wt. basis). At the same application rate, the biomass yields of Chinese cabbage and cherry tomato plants were improved by struvite compost when compared tonormal compost. Considering the increasing salinity of soil with high application rate, the optimum dosage of 5% struvite compost is recommended. To conclude, a food waste composting technology was developed to achieve good nitrogen conservation and decomposition that alleviated odour issue and produced compost with higher nutrient contents, which increased its application value

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Šaumanaitė, Kristina. "Šunų šlapimo takų akmenligė." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140305_135351-49449.

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Santrauka Tyrimas atliktas Lietuvos Sveikatos Mokslų Universitete, šio tyrimo duomenys surinkti iš veterinarijos klinikos „Veterinarinės Medicinos Centras“, 2011 – 2013 metų laikotarpiu. Darbo apimtis 30 puslapių, kuriuose yra 1 lentelė ir 10 diagramų. Darbo tikslas buvo išnagrinėti šunų susirgimo šlapimo takų akmenlige 2011 – 2013 metais sergamumą. Tiriamojo darbo uždaviniai buvo suformuluoti norint nustatyti šlapimo takų akmenligės pasireiškimo dažnumą, priklausomai nuo kitų urogenitalinės sistemos sutrikimo atvejų; kokių tipų akmenys ir/ar kristalai buvo nustatyti tyrimo eigoje, bei susidariusių susirgimų priklausomybę nuo amžiaus, lyties bei veislės. Išanalizavus 138 ligos istorijas susijusias su urogenitalinės sistemos problemomis, buvo nustatyti 47 (34,058%) šlapimo takų akmenligės atvejai. Visi sergantieji buvo išskirstyti į keletą skirtingų grupių, remiantis trimis pagrindiniais skirtumais: lytis, amžius ir veislė. Grupės skirstomos: I) pagal lytį, patelės (n=21) ir patinėliai (n=26); II) pagal amžių, buvo sudarytos keturios grupės: nuo 0 iki 3 metų (n=12), nuo 4 iki 6 metų (n=17), nuo 7 iki 10 metų (n=17) ir virš 11 metų (n=1); III) pagal veislę, buvo išskirstyta į dvi pagrindines grupes 1) grynakraujai (n=38), 22 skirtingos veislės ir 2) mišrūnai šunys (n=9). Apibendrinus tyrimo metu gautus rezultatus buvo padaryta išvada, kad šlapimo takų akmenligė pasireiškė 34,058% pacientams, iš visų susirgimų šlapimo sistemos ligomis. Iš visų tiriamųjų gausiausiai sirgo... [toliau žr. visą tekstą]
Summury The study was fufilled at Lithuanian University of Health Sciences , the study material collected from the veterinary clinic „Veterinarės Medicinos Centras“, time period of 2011 – 2013 years. Thesis volume of 30 pages, containing 1 table and 10 figure. The aim was to examine the canine urolithiasis morbidity in 2011 - 2013 years . Research work tasks have been formulated to identify urinary tract stones , depending on the frequency of occurrence of other urogenital system disruptions , what types of stones and/or crystals have been identified during the course of the study , and the resulting onset of age, sex and breed. An analysis of 138 case histories associated with urogenital problems were identified 47 ( 34,058%) of urolithiasis cases . All the patients were broken down into several different groups based on the three main differences: gender , age and breed . Sets are : I) according to gender, females ( n = 21 ) and males ( n = 26 ), II ) according to age, was formed four groups : 0 to 3 years ( n = 12) from 4 to 6 years of age ( n = 17 ) , from 7 to 10 years ( n = 17 ) and over 11 years ( n = 1 ) and III) according to the breed was split into two main groups 1 ) pure breed ( n = 38 ) , 22 different varieties and 2 ) mixed breed dogs ( n = 9). Summarizing the research results , it was concluded that urolithiasis patients experienced 34,058 % of all patients with urinary system diseases. Among the most heavily suffered from 80.851 % pure breed dogs ( p < 0.001 )... [to full text]

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Abel-Denee, Marco Mathew. "Recalcitrant nutrient removal using heterogeneous struvite precipitation in anaerobic digestion dewatering centrate." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/64144.

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The primary objective of this research was to remove recalcitrant nutrients from anaerobically digested sludge dewatering centrate. Recalcitrant nutrients are defined as small (<0.45 µm) particles or molecules containing bound phosphorus and/or nitrogen and are commonly referred to as non-reactive dissolved phosphorus and dissolved organic nitrogen. Recalcitrant nutrients will persist through wastewater treatment processes and contaminate treated wastewater. The situation is complicated by anaerobic digestion of solid residuals, which load a wastewater treatment facility with more recalcitrant nutrients through internal sidestream recirculation loops. Recalcitrant nutrient treatment may be required for wastewater treatment facilities looking to use anaerobic digestion for energy (biogas) recovery and meet stringent nutrient discharge requirement. A struvite precipitation methodology is proposed where salt crystals are encouraged to ballast colloidal particles through heterogeneous nucleation. Four biologically unique dewatering centrates were used to test the precipitation methodology on the variety of anaerobic digester configurations that can be expected from municipal wastewater treatment plant. The effect of digestion sludge retention time (2 day, 20 day) and digestion temperature (35°C, 55°C) on the removal of dissolved unreactive phosphorus and nitrogen was monitored. Averaged across all four centrates, the precipitation methodology resulted in dissolved unreactive phosphorus and nitrogen removal of 82.4% and 66.6%, respectively. Antimicrobial contaminants (triclosan, triclocarban) were observed in the precipitates at minute concentrations (<18 ng/g-dry solids). Therefore, heterogeneous struvite nucleation can provide a means of recalcitrant nutrient treatment and reactive nutrient recovery without the micropollutant burden of biosolids land application.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

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Fattah, Kazi Parvez. "Development of control strategies for the operation of a struvite crystallization process." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/26719.

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In this study, a dynamic control model for struvite crystallization process was developed that incorporated both chemistry and control software, which could be used to increase the efficiency and ease process operation. This process model was the basis of an automatic controller that had the capability to manipulate flows and chemical additions, and thereby control the system at a desired set point. The control model was then used as a prediction tool to determine conditions that influence the supersaturation ratio of the process. A pilot scale crystallizer was operated at a local treatment plant to test the model. The struvite produced from the operation of the process was then examined to determine the influence of various operating parameters on its quality. Supersaturation ratio (SSR) and upflow velocity in the crystallizer were found to influence the size and shape of the pellets developed. Mid-sized pellets (2.0-2.5 mm), had the highest crushing strengths; SSR did not appear to influence the crushing strength of pellets formed. High concentration of magnesium in the crystallizer was related to the formation of pellets having greater crushing strengths. To determine a single solubility constant for struvite, a study was conducted under varying experimental conditions. Results showed that, for a particular temperature, and in the working pH range of 7.0-9.0, the solubility constant was independent of the pH and water matrix. These experimental values, along with values found in literature, were used to derive a universal constant and a linear equation relating solubility product (pKsp) with temperature. In this study, the effectiveness of two carbon dioxide strippers, in reducing caustic usage, were evaluated. Results showed that carbon dioxide stripping was efficient in reducing caustic costs, by as much as 46%. The potential saving in caustic cost due to CO₂ stripping was calculated to be as high as 38 cents per thousand liters treated. The determination of the concentration of Mg in a struvite crystallization process is important because of its influence on SSR, the associated operational cost and its struvite forming potential when unused chemical is passed back to the treatment plant. In this study, methods were tested, with acceptable degree of accuracy, which can provide information, on-site, on the concentration and rate of application of the element.

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Wilson, Connor Walter. "Ammonia recovery from municipal wastewater through a struvite formation-thermal decomposition cycle." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45114.

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GURUSAMY, ROOPSINGH. "STRUVITE ACCUMULATION DURING THE USE OF RECLAIMED MAGNESIUM HYDROXIDE IN WASTEWATER TREATMENT." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997982513.

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Webb, Kelvin March. "The solubility of struvite and its application to a piggery effluent problem." Thesis, Webb, Kelvin March (1988) The solubility of struvite and its application to a piggery effluent problem. PhD thesis, Murdoch University, 1988. https://researchrepository.murdoch.edu.au/id/eprint/37804/.

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This project was commenced to research problems observed with a large piggery near Mandurah, Western Australia. These problems were caused by the deposition of a bio-mineral magnesium salt, struvite (MgNH4PO4.6H20), within the waste treatment system of the piggery. A review of previous research on struvite properties relevant to this project was firstly conducted, indicating the need for determination of more appropriate solubility data for struvite formation in solution. Experiments to monitor conditions at the piggery were the next stage in research. Laboratory solubility experiments were then commenced. These were at a temperature of 30oC and pH values between 6.5 and 8.5. Data were analysed as the conditional solubility constant Ps defined as below, Ps = [Mg]tX[Nh4]tX[PO4]t A qualitative comparison of field and laboratory solubility data indicates struvite may precipitate from the third and fourth lagoons in the treatment systems, and possibly the second lagoon. These inferences are by no means conclusive, and further Ps data over differing experimental conditions are required to fully explain the problem and its solution.

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Piveteau, Simon. "Optimiser l'hydrolyse et l'acidogénèse pour dissoudre et recycler le phosphore des effluents organiques en amont des unités de méthanisation." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S123/document.

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Le phosphore est un élément crucial pour la vie sur Terre, de par son implication dans les processus bioénergétiques, le stockage et le traitement de l'information génétique. C'est également l'un des nutriments limitants en agriculture, aux côtés de l'azote et du potassium. Depuis la révolution verte au milieu du 20ième siècle, le monde agricole est dépendant des engrais phosphorés à bas coûts, fabriqués à partir d'une ressource fossile et nécessaires à l'amélioration des rendements des cultures à même de répondre aux besoins en nourriture d'une population en forte croissance. Cependant cette ressource, la roche phosphatée, s'épuise progressivement. De plus, son utilisation est très peu efficiente : moins de 20% du phosphore extrait se retrouve effectivement dans la nourriture consommée. L'une des raisons de cette faible efficience est la spécialisation de régions entières dans des productions agricoles spécifiques. Ainsi, les régions spécialisées dans les cultures à hauts rendements ont besoin de grandes quantités d'engrais minéraux alors que les régions d'élevage intensif ont des excédents de lisier sans terres agricoles suffisamment grandes et proches pour servir de zones d'épandage. L'épandage excessif de lisier en Bretagne est la cause première d'eutrophisation des cours d'eau. Le phosphore contenu dans le lisier porcin pourrait être recyclé sous forme de struvite (MgNH4PO4,6H2O), un engrais phosphaté à dissolution lente, très concentré et facilement transportable vers les régions de cultures végétales nécessitant une fertilisation phosphatée importante. Le phosphore du lisier porcin étant initialement présent sous une forme minérale solide, il est nécessaire de le dissoudre avant de le précipiter en struvite. Parce-que la dissolution par acidification chimique est trop chère et implique un mauvais bilan environnemental, le procédé développé lors de cette thèse utilise l'acidogénèse, un procédé biologique au cours duquel la matière organique est convertie en acides organiques en absence d'oxygène, acidifiant naturellement le lisier porcin. Différents déchets organiques ont été testés en tant que co-substrats dans du lisier porcin brut ou digéré, provoquant une fermentation de type lactique lorsque le co-substrat possédait une forte teneur en glucides facilement biodégradables, et une fermentation avec de nombreux acides organiques produits lorsque la teneur en glucides facilement biodégradables était faible. Il a pu être démontré que la fermentation lactique était le fait de bactéries appartenant au genre Lactobacillus, alors que divers Clostridiales dominaient lors des autres fermentations avec la production d'acétate, propionate, butyrate et valérate. Un réacteur en semi continu alimenté d'un mélange de lisier brut de petit pois et de carottes a permis la dissolution de 50% du phosphore total soit 750 mg-P/L. Après centrifugation, 3.4 g d'hydroxyde de magnésium par litre de surnageant a été ajouté afin d'élever le pH à 8 et ainsi précipiter la struvite. 99% du phosphore dissous a alors été abattu. Le solide obtenu contenait 70% de struvite, un léger excès de phosphore et de magnésium, ainsi que de la matière organique. L'acidogénèse permet l'hydrolyse de la matière organique complexe et la formation d'acides organiques. De ce fait, ce procédé de recyclage du phosphore contenu dans le lisier porcin pourrait être implémenté dans les nombreuses unités de méthanisation présentes en Bretagne et qui traitent des effluents animaux ainsi que des déchets organiques d'origine agricole, industrielle et municipale. La struvite obtenue pourrait être vendue dans les régions ayant besoin de fertilisation phosphatée alors que la matière organique du digestat pourrait être maintenue en Bretagne. Un tel procédé réduirait significativement l'eutrophisation due à l'épandage excessif du lisier tout en diminuant les besoins en fertilisants minéraux fossiles grâce à une source alternative aux performances fertilisantes équivalentes
Phosphorus is a crucial nutrient for life, implicated in cellular bioenergetics as well as storage and processing of genetic information. It is also one of the limiting nutrients in agriculture with nitrogen and potassium. Since the green revolution in the middle of the 20th century, agriculture has relied on increasing amounts of cheap mineral P-fertilizers produced from a fossil resource to improve crop yields and sustain population growth. However, the resource is depleting and its use efficiency is poor: less than 20% of extracted P is actually consumed in food. One of the reasons for this is the specialization of entire regions into on type of agricultural production or another. Thus, regions focusing on high yield crops require large applications of fossil mineral fertilizers while intensive livestock breeding areas cannot find an output for their P-rich manure due to the distance with crop fields in need of P fertilization. Over application of animal manure in Brittany is the main cause of eutrophication in the region. Phosphorus could be recovered from pig manure as struvite, a concentrated, slow-release mineral fertilizer easily transported to crop-oriented regions in need of P fertilization. P in pig slurry is mostly under a solid inorganic form, requiring dissolution prior to precipitation as struvite. Because chemical acidification is too expensive and harmful to the environment, the process developed in this PhD relied on acidogenesis, a biological process in which organic matter is converted to organic acids under anaerobic conditions, thus naturally acidifying the swine slurry. Various organic wastes were tested as organic co-substrates on raw and digested pig slurry, leading to lactic acid fermentation when the co-substrate had a high content in easily biodegradable carbohydrates and a fermentation with diverse organic acids produced at low content in easily biodegradable carbohydrates. Lactobacillus was the genus responsible for lactic acid fermentation and various Clostridiales dominated otherwise, producing acetate, propionate, butyrate and valerate. A reactor was operated with semi-continuous feeding of raw swine slurry and carrot/pea, leading to the dissolution of 50% total-phosphorus or 750 mg-P/L. After centrifugation, struvite was precipitated in the supernatant by adding magnesium hydroxide to increase the pH to 8. 99% of dissolved P precipitated. The solid recovered contained 70% of struvite, a slight excess of P and Mg as well as organic matter. Because hydrolysis of organic matter and production of organic acids occurs during acidogenesis, the process could be implemented in the many anaerobic digestion units installed in Brittany treating animal manure and agricultural, industrial and municipal organic waste. The struvite recovered could be sold to regions in need while the digestate impoverished in P and rich in organic matter could be kept locally. Such process would reduce eutrophication due to over application of pig manure and also reduce the reliance on fossil P fertilizer by offering an alternative source with equivalent fertilizing performances

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Sabrina, Nandini. "Comparing the effectiveness of CO₂ strippers to reduce operating costs for struvite formation." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32320.

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Struvite crystallization offers the potential of removing phosphorus from wastewater and recovering it in a form that can be used as a fertilizer. In 1999, the Department of Civil Engineering at the University of British Columbia (UBC) started a phosphorus recovery project. The UBC struvite group is now researching ways to reduce the operating costs of struvite production. One of the major operational costs of struvite production is the cost of caustic chemicals that is added to obtain a desired level of operative pH. The main objective of this research was to introduce two types of CO₂ strippers into the struvite crystallization process and determine their effectiveness in reducing caustic chemical use, thereby helping to reduce the operational costs of struvite production. In this study, two CO₂ strippers were used - (i) compact media stripper and (ii) cascade stripper. The strippers were connected to two identical struvite crystallizers. The reactors were placed at the Lulu Island Wastewater Treatment Plant (LIWWTP). The strippers were tested under different operating conditions, and their effectiveness in reducing caustic use was compared. Throughout the project, a high percentage of phosphorus removal was achieved under each condition, by both the reactors/strippers. Most of the time, the phosphorus removal rate was around 90%. The compact media stripper failed to save any amount of caustic, regardless of the operating conditions. Instead, more caustic was required once the stripper was introduced. One of the reasons was that the stripper blocked the passage of stripped off CO₂, since it was mounted on top of the clarifier. Another reason was the susceptibility of stripper's packing media to become frequently clogged, which also resulted in blocking the movement of CO₂ through the stripping tower. On the other hand, the cascade stripper was very effective in saving caustic. The amount of caustic saved by this stripper ranged from 35% to 86%, depending on the operating conditions. Both strippers showed very poor performance regarding ammonia stripping, with the compact media stripper being slightly better in stripping ammonia. The harvested struvite pellets from both the reactors were composed of nearly pure struvite (94% by mass), with a small amount of calcium and traces of iron and potassium. Different operating conditions did not have any affect on the quality of harvested struvite.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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30

Malanda, Nicole Mulenga. "An investigation of improvements to electrochemical precipitation of struvite from source separated urine." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22980.

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Access to decent sanitation remains a problem in developing countries. At the same time, sanitation technology is constantly evolving specifically regarding resource recovery solutions. Some chemical elements found in human excreta derived from non-renewable resources, and the recycling of phosphorous from sewage in particular is a possible solution to the growing issue of resource scarcity. A potential way to recover phosphorous from urine or water-borne sewage is through struvite precipitation. Struvite (MgNH₄PO₄. 6H₂O) is a mineral that can be used as a slowrelease magnesium, ammonium and phosphate based fertilizer and can be produced from urine by adding magnesium to the ammonium and phosphate rich urine. Usually, magnesium is dosed chemically using salts such as MgCl₂, MgO, MgSO₄ or bittern, together with pH regulating agents but these reactants produce unfavourable chemical by-products and the process tends to be expensive. Previous studies have proven that electrochemical dosing of magnesium is a feasible and reliable method of struvite precipitation. It not only produces high grade struvite that is valuable and marketable, but it also eliminates the need for alkalinity dosing in order to create a suitable pH environment for struvite precipitation. Further to that, electrochemical precipitation does not produce any harmful chemical by-products. Previous work shows that one main challenge that is associated with this method is the formation of a mineral layer on the magnesium anode called nesquehonite (MgCO₃ · 3H₂O). This leads to increased electrode potentials and hence high energy consumptions and may also lead to system failures of the reactor. Further to that, struvite generally precipitates as small crystals that are difficult to separate from the solution, leading to low mass recoveries of the product. These small crystals are formed as a result of the high supersaturation, which generally occurs for most processes that are employed to make struvite. In view of these problems, this dissertation presents an investigation of the potential improvements to the electrochemical precipitation of struvite from source-separated urine. The main aim is to minimise or eliminate the formation of mineral precipitates on the anode surface. It also looks into ways of increasing the crystal sizes of the struvite being precipitated in the electrochemical system. The methodology for this investigation involved modelling and experimental work. The specific objectives for this study were to: a) Investigate how thermodynamic modelling of struvite precipitation compares to the experimental results from an electrochemical precipitation reactor, b) Employ the aspect of seeding in an electrochemical reactor for struvite production and determine the technical feasibility of the proposed process, c) Establish how to minimise the formation of nesquehonite so that the quality of struvite produced in the electrochemical reactor is not compromised, d) Investigate how the crystal sizes of the struvite particles produced in the seeded electrochemical precipitation batch reactor setup compare to those produced in the continuously stirred reactor setup with a recycle that gives the particles a longer residence time, e) Investigate the economics and energy requirements of the SEP (Seeded electrochemical precipitation reactor).

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31

Heger, Jan. "Získávání fosforu z fugátu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442835.

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The focus of this thesis is the posibility of obtaining phosphorus from liquid digestate. The theoretical part of the thesis is focused on summarizing the current situation regarding phosphorus recovery. The research summarizes the essential information about the method of struvite precipitation, by which phoshphorus is obtained in the form of struvite, which can be further used as a fertilizer. Based on the process information, an experimental device was designed to obtain phosphorus in the form of struvite, corresponding to industry standards. It is a cylindrical vessel with a conical bottom, in which the liquid digestate with the chemicals is mixed with a stirrer. The functionality of the device was tested experimentally on the created device. The results of the experiment were analyzed by XPS method, which confirmed the formation of struvite. For future operation, modifications of the device and pre-treatment of the liquid digestate were proposed, which could improve the whole process and its results.

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32

Hanhoun, Mary. "Analyse et modélisation de la précipitation de struvite : vers le traitement d'effluents aqueux industriels." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0037/document.

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La réduction des apports phosphorés des eaux usées régie par la Directive Européenne de 1991 (91/271/EEC) est considérée comme le facteur clé de la lutte contre la pollution des rivières et des lacs. Ces travaux concernent exclusivement l'étude de la formation maîtrisée de struvite (MgNH4PO4.6H2O) par précipitation comme alternative originale de récupération du phosphore et, par voie de conséquence, de l'ammonium à partir d'eaux usées. Un atout de ce procédé concerne la valorisation du précipité en tant que fertilisant. Dans ce contexte général, l'objectif consiste à développer une démarche combinant des aspects expérimentaux et de modélisation de la précipitation de la struvite. Un effluent synthétique contenant du phosphore, du magnésium et de l'ammonium a servi de solution modèle pour étudier le rôle de la température, de la concentration en réactifs, et du pH sur l'efficacité de la précipitation de la struvite ainsi que sur la distribution de la taille des cristaux obtenus. Les essais expérimentaux ont été réalisés par précipitation en cuve agitée. Diverses méthodes d'analyse des phases solide et liquide (spectrophotométrie, absorption atomique, granulométrie laser, MEB et Morphométrie) ont été utilisées. Le dosage du magnésium, ainsi que celui d'ammonium et du phosphore permet de déterminer le taux de conversion de ces composés et d'étudier une éventuelle formation d'un sous-produit. L'approche développée dans ce mémoire permet de déterminer les conditions de pH et de température favorisant l'efficacité maximale pour la récupération de la struvite. Deux voies complémentaires ont été proposées. La première étape concerne la modélisation des équilibres chimiques, d'une part, pour calculer le taux de conversion du phosphate final en fonction du pH à l'équilibre pour plusieurs températures et, d'autre part, pour évaluer l'impact de la température sur la constante de solubilité de la struvite. La stratégie numérique implique un algorithme génétique (NSGA II) pour initialiser efficacement un algorithme de résolution classique (Newton Raphson) et garantir la robustesse de la procédure. Dans la seconde étape, un modèle numérique basé sur un bilan de population couplé avec le modèle thermodynamique prédit la distribution de taille des particules,. Cette approche s'est avérée particulièrement stable d'un point de vue numérique lors du calcul des paramètres des vitesses de nucléation et de croissance, utilisés ensuite pour prédire la distribution de taille à l'aide d'une méthode de reconstruction. La forme de la distribution de taille des cristaux obtenue est typique d'un modèle nucléation – croissance. La méthodologie proposée trouve tout son intérêt pour traiter des effluents de qualité variable et prédire l'efficacité du procédé dans lequel le contrôle du pH et de la sursaturation constituent des paramètres clés
The reduction of phosphorus contribution in wastewater, governed by the European directive of 1991 (91/271/EEC) is regarded as the key factor of the fight against pollution of rivers and lakes. This work concerns exclusively the study of the controlled struvite formation (MgNH4PO4.6H2O) by precipitation as an alternative removal of phosphorus and, consequently, of ammonium from waste-water discharges. The valorization of the precipitate as a fertilizer constitutes an asset of the process. In this general context, the objective consists in developing a methodology combining an experimental approach with struvite precipitation modelling. A synthetic effluent containing phosphorus, magnesium and ammonium was used as a model solution to study the role of temperature, concentration in reagents and pH on struvite precipitation efficiency as well as on particle size distribution in a stirred tank reactor. Various analysis methods of both solid and liquid phases (spectrophotometry, atomic absorption, laser granulometry, MEB and Morphology) were used. The residual concentration of magnesium, ammonium and phosphorus allows to determine the conversion rate of these compounds and to study a likely formation of a co-product. The proposed framework is based on a two-level modelling approach. The former level, based on an equilibrium prediction of the study system Mg-PO4-NH4, involves, on the one hand, the computation of the final conversion rate of phosphate as a function of equilibrium pH at different temperatures and, on the other hand, the temperature impact assessment on struvite solubility product. The numerical strategy implies a genetic algorithm (NSGA II) to initialize a traditional algorithm of resolution (Raphson Newton) and to guarantee the robustness of the process. In the second stage, a population balance-based model coupled with the thermodynamic one predicts the particle size distribution. This approach turns out to be particularly numerically stable for the identification of nucleation and particle growth kinetics parameters that are then used to predict the size distribution, typical of a nucleation - growth model, using a method of reconstruction. The proposed methodology is particularly interesting for the treatment of industrial waste-water discharges that may be of variable quality as well as for the prediction of the process efficiency for which pH control and supersaturation constitute key parameters

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33

Ghosh, Shayok. "Optimization of phosphorus recovery from anaerobic digester supernatant through a struvite crystallization fluidized bed reactor." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60128.

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Phosphorus is an essential element for all living organisms, but its supply is limited. On the other hand, phosphorus recovery from domestic wastewater can satisfy 15-20 % of current phosphate rock demand. Moreover, struvite scaling is a concern for wastewater engineers as it clogs various equipment. Recovering phosphorus as struvite pellets from wastewater can yield sustainable solution for both problems. Although several technologies have already been available to recover phosphorus from wastewater with reasonable P- recovery efficiency, these technologies possess a number of shortcomings such as higher capital and operating cost, production of fines instead of pellets etc. This study aimed at optimization of phosphorus recovery from wastewater by developing a sustainable and efficient technology. To accomplish this purpose, a new crystallization fluidized bed reactor (FBR) was developed and impact of different physio-chemicals (supersaturation ratio) and hydrodynamic (up-flow velocity, nozzle velocity and configurations) parameters on its performance were analyzed to determine optimum operating conditions. This reactor achieved over 90% of P removal from synthetic supernatant with up to 18% of P recovery. Lower P-recovery was resulted due to lack of proper harvesting mechanism. Results showed that P-removal efficiency was increased with increase in initial supersaturation ratio up to a value of 6.5. But increase in supersaturation ratio yielded lower P-recovery with higher fines production. A value in the range of 5.5-6.0 was suggested by this study for optimum output. Low up-flow velocity was found to be associated with higher P-removal and recovery efficiency, where high up-flow velocity was found to be associated with the production of more large sized pellets and fines. But, higher nozzle velocity was found to be responsible for accomplishing higher P-removal and recovery efficiency. Two nozzles on opposite side yielded higher P-recovery efficiency with more large sized pellets and lower fine production. Based on these results, this study concluded that 40 cm/min up-flow velocity with 18.04 cm/min nozzle velocity and two nozzles on opposite side might be optimum operating conditions. Analysis on the performance of up-scaled reactor showed that optimum conditions for pilot scale and up-scaled reactor might be different due to different hydrodynamic conditions.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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34

Dhakal, Sushmita. "A laboratory study of struvite precipitation for phosphorus removal from concentrated animal feeding operation wastewater." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Dhakal_09007dcc804845b3.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 21, 2008) Includes bibliographical references.

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35

Balaguer-Barbosa, Maraida. "Recovery of Nutrients from Anaerobically Digested Enhanced Biological Phosphorus Removal (EBPR) Sludge through Struvite Precipitation." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7471.

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Water resources in Florida have been severely degraded by eutrophic conditions, resulting toxic algae blooms, which negatively affect health and tourism. Eutrophication, or excessive amount of phosphorus (P) and nitrogen (N) in water, overstimulates the production of aquatic plants, depletes dissolved oxygen, and deteriorates the aquatic environment. However, phosphorus is a non-renewable resource essential for all living organisms. In fact, more than half of the total demand for P globally is to supply the food industry, which has concerningly accelerated the depletion rates of phosphate reserves. In many wastewater treatment plants (WWTPs), the enhanced biological phosphorus removal (EBPR) approach has been employed to achieve high phosphorus removals from wastewater through phosphate-accumulating organisms (PAOs). However, during either anaerobic or aerobic digestion of EBPR sludge, stored polyphosphates are released and carried into the sidestream, which is typically returned to the headworks of the main treatment facility, thereby recycling phosphorus back into the system. This treatment train is highly inefficient because nutrients rather are recirculated rather than recovered. Struvite (MgNH4PO4•6H2O) is precipitated in oversaturated aqueous solutions with equal molar concentrations of magnesium, ammonium, and phosphate. The controlled crystallization of struvite may be applied to remove phosphorus and some ammonium from sidestreams, which is the liquid portion of the digester effluent. Struvite can be employed as a sustainable slow-release fertilizer due to its low solubility in water. This offers the opportunity of marketing the struvite produced under controlled conditions and creating a revenue for the utility. The specific research objectives of this thesis are (1) to investigate different possible operating conditions under which anaerobically digested sludge from EBPR facilities might be treated through struvite precipitation; (2) to quantify the removal of N and P from sidestreams from anaerobically digested EBPR sludge via struvite precipitation and assess the composition of the precipitate obtained; and (3) to generate a cost analysis to assess the trade-offs between the capital and operation and maintenance (O&M) costs of struvite production and the benefits such as reduced chemical use and production of a slow-release fertilizer. The main parameters affecting struvite precipitation are the Mg2+ to PO43- molar ratio, pH, temperature, mixing speed, hydraulic retention time (HRT), and the seed quantity added to promote nucleation. Different operating conditions within these parameters were batch-tested as part of this study using sidestream from the pilot-scale anaerobic digester (AD) fed from Falkenburg Advanced Wastewater Treatment Plant (FAWWTP) EBPR sludge. Additionally, the effect of temperature and pH were investigated using Visual MINTEQ simulations. Analysis of Variance (ANOVA) was employed to investigate the variance within the removals from the centrate obtained for phosphate, ammonium, magnesium, and calcium. The chemical composition of the solids collected after employing the selected operating conditions was analyzed by powder X-ray diffraction (PXRD). The results for the batch tests performed as part of this thesis were quantified in terms of the removals of phosphate, ammonium, magnesium, and calcium from the centrate. The greatest amount of phosphate removal was achieved by operating the struvite reactor at 4.0 mmol of Mg2+ per mmole of PO43-. The other molar ratios tested were 1.0, 2.0, and 3.0. Visual inspection of the data showed significant variability in removals of ammonium, calcium, and magnesium, which are likely to be correlated with the highly variable influent concentrations into the struvite reactor. In this case, ANOVA will require larger data sets to accurately analyze variance in the results. The statistical results given by ANOVA for the pH suggests that the main species to contribute with struvite being precipitated are statistically stable within the tested pH values of 8.5, 9.0, and 9.5. The results obtained by the simulation using Visual MINTEQ indicated that maximum saturation as function of pH takes place at a pH between 9.5 and 10.0. The ANOVA for the mixing speed showed that significant amounts of ammonium were removed at higher mixing speeds. This is likely due ammonium being volatilized, which is enhanced by turbulence. Magnesium and phosphate showed lower removals at higher mixing speeds, suggesting that too high mixing speeds will promote struvite seed dissolution. ANOVA identified NH4+ and Ca2+ as the species significantly impacted by modifying the HRT from 8 to 20 minutes. This suggests that prolonged HRT promotes inorganic nitrogen species to volatilize. It is likely that at higher HRT, tricalcium phosphates (TCP) or other favored calcium species coprecipitated together with struvite. Regarding the added struvite seed for nucleation, the greatest removals of ammonium, magnesium, and, phosphate were observed when 1g/L of struvite seed was added. The results also indicated that adding 5 and 10 g/L was an excessive amount of seed, which ended up contributing significantly to more nutrients into the centrate rather than precipitating them. The results also suggested that the struvite crystals formed in the sidestream by secondary nucleation, since removals close to zero were reached after adding no seed. The optimum temperature identified by the simulation in Visual MINTEQ was 21°C. Operating the struvite reactor under the optimal conditions identified in the batch tests, resulted in an average of 99% total P (TP) and 17% total N (TN) removals. The precipitate molar composition for [Mg2+:NH4+:PO43-] was equal to [2:2:1] based on the concentrations that disappeared from the aqueous solution, suggesting that other minerals coprecipitated with struvite. Visual MINTEQ predicted that together with struvite, CaHPO4 and CaHPO4•2H2O will also precipitate under the tested conditions. However, given the obtained ratio it is likely that other unpredicted species by Visual MINTEQ, such as magnesium carbonates or magnesium hydroxide coprecipitated with struvite. PXRD analysis also revealed that the sample was likely contaminated struvite, although the specific contaminants were not identified. A cost analysis was performed to distinguish the economic feasibility of incorporating a struvite harvesting system to treat the anaerobically digested sidestream from the Biosolids Management Facility (BMF) within the Northwest Regional Water Reclamation Facility (NWRWRF). Three different scenarios were evaluated; in Scenario (1) Ostara® Nutrient Recovery Technologies Inc. (Ostara®) evaluated the production of struvite from anaerobically digested EBPR sidestream using a fluidized reactor. In Scenario (2), Ostara® evaluated the production of struvite in a fluidized bed reactor by employing Waste Activated Sludge Stripping to Remove Internal Phosphorus (WASSTRIP™) in a mixture of post-anaerobic digestion centrate and pre-digester thickener liquor. Scenario (3) was addressed by Schwing Bioset Inc. (SBI) for a continuously-stirred reactor followed by a struvite harvesting system. Scenario (2) offers the highest TP and TN recoveries through WASSTRIP™ release due to the additional mass of phosphorus that is sent to the phosphorus recovery process. Therefore, although Scenario (2) has the highest total capital costs ($5M) it also has the shortest payback period (18 years). Scenarios (1) and Scenario (3) have similar payback periods (22-23 years) but very different total capital costs. The annual savings by producing struvite in Scenario (3) is $40K, which is about 30% less than producing struvite in Scenario (1). This is probably because the only savings considered under Scenario (3) were the lower alum usage and the fertilizer revenue; however, the savings by producing class A biosolids, were not accounted for. Consequently, the reduced total capital cost of $960K and the annual payment amount per interest period close to $80K, positioned Scenario (3) as the more feasible one, considering 20 years as the expected life of the asset at a 5% interest rate.

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36

Yilmazel, Yasemin Dilsad. "Removal And Recovery Of Nutrients As Struvite From Anaerobic Digestion/co-digestion Residues Of Poultry Manure." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610800/index.pdf.

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The main objective of this study was to investigate the removal and recovery of nutrients from anaerobic digestion residues of poultry manure through struvite (MgNH4PO4.6H2O, MAP) precipitation. To this purpose, three sets of laboratory experiments were conducted. In the first set, separate and co-digestion of poultry manure and sewage sludge were studied in laboratory-scale mesophilic anaerobic batch reactors and subsequent struvite precipitation experiments were conducted with the reactors effluents. The effects of important parameters on struvite precipitation were investigated and it is illustrated that up to 89 % of NH4-N, 84 % PO4-P and 42 % COD removals were possible. In the second set, the effluents of a full-scale co-digestion plant utilizing poultry manure and maize silage were subjected to struvite precipitation experiments. Acidic phosphorus-dissolution process was successfully applied to the solid phase effluents to obtain phosphorus-enriched solution. By the addition of external Mg and P more than 90% of NH4-N and PO4-P were recovered from phosphorus-enriched solution, whereas the addition of only Mg led to partial recovery of NH4-N. In the third set, the effluents of a full-scale poultry manure digester were subjected to struvite precipitation experiments. The findings illustrated that Ca has inhibitory effects on the struvite reaction and lead to formation of hydroxlyapatite and amorphous calcium phosphates together with struvite. Based on the results obtained in this study, it is postulated that, struvite precipitation is a viable option for the recovery of the nutrients in the anaerobically digested poultry manure. This study illustrated that, poultry manure, if managed properly, could meet one-fourth of Turkey&
#8217
s domestic fertilizer demand.

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37

Bhuiyan, Md Iqbal Hossain. "Investigation into struvite solubility, growth and dissolution kinetics in the context of phosphorus recovery from wastewater." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31257.

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The present research was conducted to investigate the mechanisms controlling formation, dissolution and decomposition of the mineral, struvite (MgNH₄PO₄•6H₂O) in the context of phosphorus recovery from wastewater. Solubility, thermodynamics, kinetics and thermal decomposition of struvite were studied in laboratory and wastewater treatment environments to gain knowledge to optimize the phosphorus recovery process from wastewater through struvite crystallization. The thermodynamic solubility products (Ksp) of struvite were determined by extrapolating measured solubility product values to zero ionic strength, with -log Ksp of 13.36(±0.07) at 25⁰C, using an appropriate activity coefficient model. A representative temperature compensation factor (a = 0.0198⁰C-¹) has been derived for electrical conductivity (EC) correction, and a relationship between ionic strength (I) and EC has been developed for anaerobic digester supernatant/centrate samples from five different wastewater treatment plants in western Canada. The metastable region, where nucleation is negligible, for struvite precipitation was explored in this study. This region was used in a kinetics study to suppress nucleation of struvite during growth experiments in a bench-scale fluidized bed reactor (FBR). A linear growth rate model has been tested and proposed, which was found to be effective for struvite growth determination in FBRs. The dissolution processes of struvite were investigated in a batch reactor system using two different theoretical models. The experimental values of struvite dissolution were found to fit well with both models. In a mixed flow-through reactor system, the dissolution rates for struvite pellets were found to increase with the hydrogen ion concentration in the acidic pH, while the rate of dissolution in the alkaline pH was found to increase due to hydroxyl-promoted dissolution. The thermal decomposition study of struvite showed that the simultaneous loss of both ammonia and water molecules from the struvite structure occurred gradually as a function of temperature, rather than as a distinct step. A pilot-scale struvite recovery FBR developed at The University of British Columbia (UBC) was operated, using the knowledge gained from the thermodynamics and kinetics experiments. The pilot-scale FBR was found to be effective in recovering phosphate from anaerobic digester centrate in the form of a nearly pure struvite.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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38

Rahaman, Md Saifur. "Phosphorus recovery from wastewater through struvite crystallization in a fluidized bed reactor : kinetics, hydrodynamics and performance." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/38532.

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Struvite crystallization from wastewater, using a novel fluidized bed reactor developed at UBC, offers a significant reduction (80—90%) of soluble phosphate from waste streams and generates a product that can be reused as a slow release fertilizer. To implement this green technology at a plant scale, a reactor model that incorporates process kinetics, thermodynamics and the system hydrodynamics, is required. Therefore, the main objectives of this dissertation were to study the struvite precipitation kinetics, thermodynamics, and fluidization characteristics of the struvite crystals bed, and finally, develop a model based on this information. Both dissolution and precipitation experiments were carried out in a jar test apparatus to study the solubility and precipitation kinetics of struvite. The struvite solubility product, pKsp values were found to vary from 13.43—14.10, for different water and wastewater samples tested at 20°C. Also, a correlation was developed to estimate struvite solubility at different temperatures. In struvite precipitation experiments, the operating conditions of supersaturation, pH, Mg:P ratio, mixing and seeding conditions were varied to identify the effect of those process parameters on the precipitation kinetics. The kinetic rate constant increases with increasing both the supersaturation and Mg:P ratios. Both the mixing energy and seeding rate were found to have minimal effect on ortho-P removal. Detailed experimental and numerical investigations of the fluidization characteristics of struvite crystals were performed. The bed expansion behaviour of mono-sized struvite crystals can be represented reasonably well by the Richardson-Zaki relation and the expansion characteristics of poly-dispersed struvite crystals bed can be predicted by the ‘serial model’. The CFD simulated bed expansion behaviour of the crystals bed was found to be consistent with the experimental results. Also, CFD simulations were capable of capturing the mixing/segregation behavior of a fluidized-bed of multi-particle stnivite crystals. Finally, a mathematical model was developed by assuming a complete segregation of the bed crystals and liquid movement as plug flow in the reactor. The model predictions provided a reasonably good fit with the experimental results for both P0₄-P and NH₄-N removal. The model predicted mean size of product crystals matched reasonably well with pilot scale experimental results.

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Zhang, Hui. "Pilot scale application of microwave technology for dairy manure treatment and nutrient recovery through struvite crystallization." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44766.

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Excessive use of nutrients in agriculture has been significant surface and groundwater pollution sources. A pilot scale treatment process was developed for the purposes of phosphorus and ammonia recovery from dairy manure slurry. A novel advanced oxidation process combining hydrogen peroxide, microwave, and sulphuric acid was studied for its abilities to solubilise nutrients and metals in manure. The treated manure was then used for struvite crystallization to recover phosphates and ammonia in a commercially viable fertilizer form. Using dairy manure, as a phosphate source for struvite crystallization, had some foreseeable challenges. The majority of phosphorus in dairy manure slurry was insoluble, thus unsuitable for struvite crystallization. A synergistic nutrient solubilisation effect was found when manure was treated. As high as 101.7 ± 4.3% of total phosphorus was solubilised as phosphate, and 94.9 ± 4.7% of total nitrogen was solubilised as ammonia. High suspended solids concentration in manure slurry, thought to impede struvite crystallization, was also overcome through microwave treatment to destabilise manure solids from suspension. As high as 2.00 Log reduction in total suspended solids was achieved by gravity clarification. Manure contains high levels of calcium that would compete against struvite for phosphate precipitation. Oxalic acid was tested as a potential reagent to use for calcium removal from dairy manure. Up to 97.2% soluble Ca removal, by calcium oxalate precipitation was observed. The treated dairy manure was then used as influent material for struvite crystallization. Under various reaction conditions, it was found that phosphorus reduction between 69% and 99% was achievable. Roughly 25% nitrogen removal was observed under all reactor conditions. An interesting observation from the crystallization experiments was that pellet morphologies and compositions varied with reaction conditions. The potassium containing mineral hazenite was found to coexist in the struvite pellets. The ability to extract potassium from dairy manure was not only beneficial to the dairy industry, but may also create a fertilizer of higher economical and nutritional value, than struvite alone.

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40

Robles-Aguilar, Ana Alejandra [Verfasser]. "Towards a more efficient and sustainable fertilization through recycling phosphorus as struvite / Ana Alejandra Robles-Aguilar." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/117389859X/34.

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Robles-Aguilar, Ana [Verfasser]. "Towards a more efficient and sustainable fertilization through recycling phosphorus as struvite / Ana Alejandra Robles-Aguilar." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/117389859X/34.

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42

Wu, Qingzhong. "Potential Applications of Magnesium Hydroxide for Municipal Wastewater Treatment – Sludge Digestion Enhancement and Nutrient Removal." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1019595719.

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43

Tansman, Gil Fils. "Development and Implementation of Methods to Study Crystallization in Cheese." ScholarWorks @ UVM, 2017. http://scholarworks.uvm.edu/graddis/747.

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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.

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Hassan, Parssa. "Simultaneous management of nitrogen and phosphorus in dewatered sludge liquor by combining ANAMMOX process with struvite crystallization." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45119.

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A process combination of anaerobic ammonium oxidation (ANAMMOX), followed by struvite crystallization, was examined for simultaneous removal of nutrients (nitrogen and phosphorus) from dewatered sludge liquor or centrate. Phosphorus recovery as struvite can recover more than 90% P from centrate; however, the effluent after struvite crystallization still contains high concentrations of ammonium nitrogen (NH₄-N). ANAMMOX is a cost effective alternative process for NH₄-N removal and this process can remove 85% - 90% of NH₄-N from centrate, but leaves high concentration of phosphorus phosphate (PO₄-P) in the treated effluent. Combining ANAMMOX and struvite recovery can offer a sustainable solution for managing phosphorus and nitrogen at wastewater treatment plants. The ANAMMOX process, followed by a struvite crystallization process, was selected as the combination sequence for this first study. Synthetic feed was prepared with different molar ratios of Mg: NH₄-N: PO₄-P to mimic centrate, partially nitrified centrate and centrate treated by ANAMMOX process (ANAMMOX effluent). To determine the molar ratio of Mg: NH₄-N: PO₄-P, centrate was obtained from Lulu Island Wastewater Treatment Plant and partial nitrification, followed by ANNAMOX process, was conducted on this batch of centrate. Jar tests were conducted to determine the struvite formation potential from synthetic ANAMMOX effluent, as it has a very low N: P ratio. Pure struvite formed successfully in the jar tests with P-removal efficiency up to 88%. The process combination was upgraded to bench-scale, fluidized bed reactors for further investigation on the nutrient recovery efficiencies and associated chemical costs. The process combination successfully reduced NH₄-N concentration to 70 mg/L from an initial value of 800 mg/L. The concentration of PO₄-P was reduced to 15 mg/L in the final treated effluent, from a starting value of 119 mg/L. Overall, the combination resulted in phosphorus-phosphate (PO₄-P) removal rate as high as 87% and ammonium-nitrogen (NH₄-N) as high as 92%. The mean particle size for struvite from ANAMMOX effluent ranged between 90 - 160 μm, and was larger than struvite particle formed from centrate. However, chemical costs associated with caustic and magnesium consumption, were found to be higher for the process combination, compared to just struvite formation using centrate.

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45

Faucher-Capdevielle, Aurélie. "Influence des paramètres physico-chimiques et des caractéristiques de la matière organique sur les cinétiques de formation de struvite : application au recyclage du phosphore des lisiers de porcs." Rennes 1, 2012. http://www.theses.fr/2012REN1S117.

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L'objectif de la thèse est de développer les connaissances sur la cristallisation du phosphore (P) nécessaires à la mise au point de procédés de recyclage du P des effluents organiques dont les lisiers de porcs. Le produit formé doit être sous une forme minérale substituable aux engrais phosphatés. Le procédé retenu pour valoriser le P du lisier de porcs traité est la dissolution du P minéral particulaire suivi d'une séparation de phase puis de la précipitation des phosphates en struvite (MgNH₄PO₄·6H₂O) par ajout de magnésie (MgO). Le produit de cristallisation est récupéré dans des sacs filtrants à 100 µm. Un des verrous de ce procédé est l'obtention de cristaux de struvite d'une taille supérieure à 100 µm. Un plan d'expérience a permis d'optimiser la précipitation de struvite en faisant varier les paramètres procédés. Les essais ont tout d'abord été réalisés en milieu synthétique de composition ionique similaire au lisier de porcs. En conditions optimales, P est recyclé majoritairement en cristaux de struvite et ce malgré les fortes concentrations en calcium. L'abattement total du P est de 90% dont 80% sous forme de struvite. Entre 70 et 80% des cristaux ont une taille supérieure à 100 µm. L'optimisation de la précipitation du P a permis de mettre en évidence le rôle prépondérant de la magnésie sur la qualité du produit. Le deuxième paramètre important est le ratio molaire N :P qui favorise la formation de struvite au lieu de phosphate de calcium. Les cinétiques de précipitation mettent en évidence la co-précipitation de phosphates calciques amorphes (ACP) et de struvite. Puis, l'ACP se dissous progressivement pour rétablir l'équilibre en phosphate du fait de la précipitation en struvite. L'influence de la matière organique sur la précipitation du P en conditions optimisées a été testée sur trois fractions du surnageant de lisier traité biologiquement et acidifié. En présence de matière organique, la précipitation est plus lente mais les cristaux sont plus gros et non agglomérés
The aim of this thesis is to understand phosphorus (P) crystallization in order to develop P-recycle processes in high concentrated organic effluents such as swine wastewaters. The product has to be mineral to substitute phosphates fertilizers. The process chosen to recycle phosphorus from biologically treated swine wastewater starts with the dissolution of the mineral particular P. Liquid and solid phases are then dissociated by filtration. Phosphates are then precipitated as struvite (MgNH₄PO₄·6H₂O) by adding magnesia (MgO). The solid product is recovered in filter bags whose size cut-off is 100 µm. The bottleneck of this process is to obtain struvite crystals with a size greater than 100 µm. An experimental design was developed to optimize struvite precipitation by varying the process parameters. These tests have first been made in a synthetic medium with a ionic composition similar to the swine wastewater studied. Under optimal conditions, P is recycled mainly in struvite crystals despite the high concentrations of calcium. The total reduction of P is 90% and 80% was precipitated as struvite. Between 70 and 80% of the crystals have a size greater than 100 µm. The optimization of phosphorus precipitation has highlighted the role of magnesia on the quality of the product. The second important parameter is the molar ratio N: P which promotes the formation of struvite instead of calcium phosphate. The precipitation kinetics evidence the co-precipitation of amorphous calcium phosphates (ACP) and struvite. The ACP, an unstable mineral, starts to dissolve within minutes to restore the balance of phosphate in the solution due to the precipitation of struvite. The influence of organic matter on the precipitation of phosphorus was tested in optimized conditions on three fractions of the supernatant of an acidified biologically swine wastewater. With organic matter, the precipitation rate is slower but the crystals are larger and not agglomerated

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46

Wu, Zhenyu. "Exploring Forward Osmosis Systems for Recovery of Nutrients and Water." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/81881.

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Livestock wastewater contains a large amount of nutrients that are available for recovery. In this study, a proof of concept process based on forward osmosis (FO) was proposed and investigated for in-situ formation of struvite from digested swine wastewater. This FO system took advantage of a drawback reverse solute flux (RSF) and used the reversed-fluxed Mg^{2+} for struvite precipitation, thereby accomplishing recovery of both water and nutrient. With 0.5 M MgCl2 as a draw solution, high purity struvite formed spontaneously in the feed solution and the water flux through the FO membrane reached 3.12 LMH. The precipitated struvite was characterized and exhibited a similar composition to that of commercial struvite. The FO system achieve >50% water recovery, >99% phosphate recovery (given sufficient magnesium supply), and >93% ammonium nitrogen removal from the digested swine wastewater. The recovered products (both struvite and water) could potentially generate a value of 1.35 $ m^{-3}. The results of this study have demonstrated the feasibility of nutrient recovery from livestock wastewater facilitated by FO treatment.
Master of Science

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Basiri, Neshat. "A curious insight into removal and recovery of ammonia from struvite thermal decomposition unit outlet by acidic adsorption." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57797.

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In this study investigated the recovery of ammonia from the hot and humid gas outlet of a struvite thermal decomposition unit. Based on the project objectives and the initial studies, adsorption of the ammonia by oxalic acid dihydrate was selected as the ammonia removal method. Oxalic acid’s solid form not only would reduce the energy loss through adsorption, but also could be a potential carrier for the final product that could be used as a nitrogen fertilizer. This research presents experimental stages specifically designed for recovering the ammonia and energy of this stream. Experiments started in ambient temperatures and humidity to gain a good understanding of the process. Later, it evolved to simulate the actual conditions of the struvite thermal decomposition unit outlet. During the investigation phase, factors such as flow rate, adsorbent crystal size, and contact time were recognized as the most influential parameters for this process. The efficiency of ammonia removal could be optimized to stay above 90% by controlling these factors in a two-hour period. In the next phase, as the struvite thermal decomposition unit had output conditions of 80°C and relative humidity of 80%, experiments were continued by accommodating these conditions. At this stage, difficulties were observed in the stability of initial adsorbent. This led to a substitution of this adsorbent with anhydrous oxalic acid and potassium tetraoxalate dehydrate. The results indicated a high capacity and potential for ammonia adsorption. Despite the adverse effects of high temperature on adsorption processes, ammonia removal efficiency could be kept above 93% at all times, with modifications in the reactor for setting a good range of contact times for the adsorption. Although ammonia removal from the stream could achieve high efficiencies the ammonia capture in the adsorbents never exceeded 10-15% of the maximum theoretical adsorption. This suggested that the adsorption is only occurring in the surface layer of the adsorbents and the ammonia molecules are not penetrating and reacting with the total acid mass. Therefore, it is recommended that further research be continued, to gain new insight into this problem.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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48

Daumer, Marie-Line. "Analyse des transformations du phosphore lors du stockage et du traitement biologique et physico-chimique des lisiers de porc en vue d'un recyclage." Toulouse, INSA, 2007. http://eprint.insa-toulouse.fr/archive/00000176/.

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Pour favoriser le recyclage du phosphore des lisiers de porcs sous la forme d'engrais chimique, facilement exportable et valorisable en dehors des zones de production animale intensive, il est nécessaire de séparer le phosphore de la matière organique. Le phosphore des lisiers étant initialement à plus de 60% sous une forme minérale solide mélangée à la matière organique, nous avons conçu un procédé en 3 étapes : (1) solubilisation du phosphore, (2) séparation solide/liquide puis (3) précipitation. La solubilisation constitue le principal verrou technologique à la mise en place de ce procédé. Nous avons donc étudié trois stratégies/possibilités de solubiliser le phosphore et d'augmenter ainsi la proportion de la fraction dissoute du phosphore. La première stratégie évaluée est l'ajout d’acide benzoïque à la ration des porcs et la réduction du taux de protéines. Cette modification de la ration alimentaire réduit le pH des lisiers d’une unité environ, augmentant ainsi la proportion de phosphore dissous dans le lisier stocké jusqu'à 20% du phosphore total. Cette augmentation reste toutefois insuffisante pour envisager un procédé de recyclage performant. La seconde stratégie est l'optimisation du relargage de phosphore lors du traitement biologique de l'azote des lisiers par aération intermittente. Les résultats obtenus au cours de ce travail ont montré que les métabolismes de relargage/accumulation du phosphore sont masqués par l'effet du pH lors de ce traitement biologique. En effet, le pH élevé provoque la précipitation du phosphore relargué pendant l'anaérobiose alors que, au contraire, l'acidification du milieu induite par la nitratation, provoque la dissolution des formes minérales pendant l’aérobiose. Cette dissolution masque l'accumulation du phosphore par la biomasse pendant l’aération. Une augmentation significative de la concentration en phosphore dissous est obtenue en augmentant la concentration d’azote nitrifié par cycle (augmentation de la durée des cycles et réduction du temps de séjour). Cependant, la fraction de phosphore dissous par ce biais ne dépasse pas 20-25% du phosphore total. La troisième possibilité est l’utilisation de réactifs acides. Dans ce cas, la réduction du pouvoir tampon des lisiers, obtenus avec les régimes alimentaires acidifiants ou après traitement biologique permet d'envisager une forte réduction de réactif lors d'un procédé de dissolution par ajout d'acide puis de précipitation. Suite à la dissolution du P par ajout d'acide, des essais de précipitation ont été effectués avec ajout de soude, de bicarbonate de soude ou de magnésie. La précipitation de la totalité du P a été obtenue a partir de pH 7 et les principales formes obtenues et identifiées sont la struvite et une forme non cristalline de calcium phosphate. Enfin, le logiciel de modélisation géochimique PHREEQCI a été évalué au cours de ce travail et permet de simuler l'effet de l’ajout d'acides ou de bases dans le milieu et de donner une description qualitative des phases solides obtenues
To recycle phosphorus from pig slurry, as a chemical fertilizer which could be easily transported and used far from intensive livestock areas, it is necessary to remove phosphorus from organic matter. Since pig slurry has more than 60% of its phosphorus in solid mineral form we have designed a three step process of solubilisation, solid/liquid separation and precipitation to realise such a reduction. The solubilisation was the main obstacle in the development of this process. We have studied three means to increase the ratio of dissolved phosphorus. The first one was to add benzoic acid and to reduce the amount of protein in the pig feed. The pH was reduced by 1and the dissolved phosphorus ratio increased up to 20% after storage, but it was not sufficient for the recycling process. The second one was to optimise phosphorus release during the biological treatment of nitrogen by sequential aeration. Both biological phosphorus release and uptake were concealed by the effect of pH. The high level of pH led to the precipitation of released phosphorus during the anaerobic stage. Contrary to this, acidification induced by nitrification led to solubilisation of mineral forms of phosphorus which concealed the uptake of phosphorus during the aerobic stage. A significant increase of dissolved phosphorus was obtained by increasing the amount of nitrogen nitrified in one cycle, which was accomplished by increasing the cycle duration and decreasing the hydraulic retention time. However, the ratio of dissolved phosphorus was always less than 20-25%. The third way was to use an acidic reactant. This could be viewed only if the buffer effect was previously reduced by feeding the pigs with the acidifying diet or by biological treatment. After acidic solubilisation, phosphorus was precipitated as struvite and amorphous calcium phosphate by adding either sodium hydroxide, sodium carbonate or magnesium oxide. The geochemical modelling tool PHREEQCI was successfully used to simulate acid or base addition in slurry and was helpful to give a description of the solid phase composition

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Joshua, Nilmini Sureka, University of Western Sydney, and Faculty of Science and Technology. "Novel phosphate bonding composites." THESIS_FST_XXX_Joshua_N.xml, 1997. http://handle.uws.edu.au:8081/1959.7/282.

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A cement material has been developed that has a controllable set time, compressive strength of about 50 MPa and shrinkage of under 2% when heated to 960 degrees centigrade. The main compound of this material has been shown to be the potassium analogue of struvite, in which potassium ion is substituted for the ammonium ion. The cement is formed by reacting a slurry made with potassium carbonate and monoammonium phosphate with magnesium oxide. Ihe amount and rate of addition of water to the mixture is controlled to determine the set time. It has been demonstrated that this cement may be used as a matrix in conjunction with cenospheres or cellulose fibres to form a low density composite material, and with silica powder to form a high strength composite. As well as optimising the cement mix for maximum strength and minimum shrinkage, a variety of properties of the K-cement were investigated. It was found that long term exposure of the cement to the atmosphere does not result in the formation of magnesium carbonate, but long term exposure to saline solutions can result in the formation of dypingite on the surface. No effect on strength was observed as a consequence of the age of the slurry or the cement, within 1-2 weeks
Doctor of Philosophy (PhD)

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50

Marques, José Luciano Verçosa. "Remoção de fósforo do líquido de descarte do desaguamento do lodo de estações de tratamento de esgoto mediante precipitação de estruvita." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-06012011-104749/.

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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.

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