Papers by Keyword: Struvite

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Authors: Ming Yang Zhang, Jian Wei Du, Takahiro Kuba, Yong Wen
Abstract: Phosphorus is a necessary nutrient element to all lives in the world. Distribution and phosphate rock reserves in the world disclose shortage crisis of phosphorus. Thus phosphorus recovery has been a research hot spot in the world. Mr.Ohtake’ group [1] recommended a new method to recover phosphorus from sewage sludge during heating process. It seems that nearly 90% of the poly-phosphate (poly-P) and 87% of total phosphate (T-P) can be released from cultivated sludge by heating at 70 °C for 1 hour. Meanwhile, released poly-P can precipitate with Ca in neutral condition without any pH adjustment. Sewage sludge was used in this research to identify its performance during thermal treatment. With the increase of temperature and heating time, release of poly-P and T-P increased obviously. However, poly-P would be hydrolyzed when temperature was higher than 80 °C. With addition of EDTA, release of poly-P increased nearly 100%. Migration of metal cations during thermal treatment can provide indirect evidence which kinds of metal cations would make impediment on poly-P release. A novel phenomenon was observed poly-P mixed with ortho-phosphate can precipitate with NH4+ and Mg2+ as struvite at pH 8.5.
Authors: Tao Zhang, Ci Fang, Ping Li, Rong Feng Jiang
Abstract: Struvite crystallization is an efficient method for phosphorus recovery from animal manure wastewater. However, large amount of organic coexisting impurities, contained in animal manure wastewater, might influence struvite crystallization. In this study, the effect of typical organic matter contained in animal manure wastewater, such as butyric acid, fulvic acid, tetracycline, on phosphorus recovery was examined. The following conclusions were drawn: (1) with an increase in butyric acid concentration in animal manure wastewater, phosphorus recovery efficiency did not change significantly; (2) with an increase in fulvic acid concentration in animal manure wastewater, phosphorus recovery efficiency decreased obviously; (3) with an increase in tetracycline concentration in animal manure wastewater, phosphorus recovery efficiency decreased slightly.
Authors: Hong Rui Yang, Ya Lei Zhang, Ue Fei Zhou, Hong Guang Zhu
Abstract: Fermentation wastewater generated from livestock and poultry breeding contains high strength of ammonium-nitrogen and phosphorus, which has the huge nutrient recovery value. To recover nitrogen and phosphorus from the fermentation wastewater, struvite precipitate is a promising option. This paper focused on the ratios of reagent adding and pH optimizing during the ammonium and phosphate recycling through struvite precipitate. Using MgCl•6H2O and NaHPO4•12H2O as precipitants, the optimum conditions were discussed in the paper. The results indicated that during a reaction time of 30min and a mixed speed of 100r/min , the ammonium and phosphate were removed by 89% and 88.7%, respectively at pH 10.5 and a molar ratio of Mg:N:P=1.2:1:1. In addition, it could reduce the organic matter content with a COD(Chemical Oxygen Demand ) removal efficiency of 36.2%. The recovered struvite had been suggested to display excellent fertilizer qualities, and also could be recycled and reused as a resource of nitrogen and phosphorus.
Authors: Andrea Ewald, Bernhard Lochner, Uwe Gbureck, Jürgen Groll, Reinhard Krüger
Abstract: Mg-phosphate ceramics have aroused growing interest as bone replacement materials due to their ability to degrade under physiological conditions. To mimic cancelous bone and to promote tissue repair mechanisms a highly macroporous structure with open cells is desired. In this study trimagnesium phosphate (farringtonite, Mg3(PO4)2) and struvite ((NH4)Mg(PO4)·6H2O) scaffolds were developed as open cell foams using the Schwarzwalder-Somers technique and optimized for pore size and mechanical performance. Polyurethane (PU) foam (20-80 ppi) was used as a template. For the optimization of the farringtonite scaffolds, ppi number of the PU foam as well as the technique that was used to remove excess slurry were varied. Sample characterization was done by SEM, XRD and compression testing. For best results were obtained using 60 ppi PU foams leading to a compressive strength of 58 kPa (90 % porosity). Farringtonite scaffolds were modified by either polymer infiltration or transformation into struvite with an ammonium phosphate solution. The pore macrostructure was retained for both of these processes and a reduction of porosity was observed. The microstructure of struvite foams was significantly altered showing larger and more facetted crystals than farringtonite. Mechanical properties substantially improved by transformation into struvite to 730 kPa (68 % porosity). Cytocompatibility was tested using osteoblasts and fibroblasts. Cell number and cell activity (WST) were tested over a period of 3 to 13 days. Farringtonite foams showed a tendency for higher cell numbers than struvite, while the WST activity was similar. Infiltration of farringtonite with PLGA approximately doubled cell number compared to pure farringtonite. In conclusion macroporous Mg-phosphate foams have been successfully produced. Compressive strength of the foams was drastically improved by optimization of pore fineness, transformation to struvite and infiltration with PLGA. The open porous structure was retained and the materials showed good cytocompatibility.
Authors: Ming Yang Zhang, Ai Min Hao, Takahiro Kuba
Abstract: Because of the shortage crisis of phosphorus element and environmental problems caused by excess discharge of phosphorus compounds into nature water bodies, phosphorus recovery had been research hotspot. Poly-phosphate (poly-P) released from sewage sludge after thermal treatment could be recovered successfully as magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O) commonly known as struvite in present study. This phenomenon was the first time to be found in phosphorus recovery from sewage sludge. The parameters affected struvite formation with poly-P had been tested. Poly-P indicated better characteristics in phosphorus recovery compared with ortho-phosphate (Pi) because it can be precipitated at lower pH condition even neutral condition, with less addition of magnesium element.
Authors: Hai Ming Huang, Qian Wu Song, Chun Lian Xu
Abstract: Struvite (MgNH4PO4∙6H2O) is an insoluble double salt. It can precipitate in places such as pipes, aerators and pumps, which could lead to substantial problems influencing the normal operation of wastewater treatment equipments. At present, removal of ammonium nitrogen from various wastewaters by the formation of struvite has been widely investigated. This paper reviewed the research and application efforts concerning the treatment of ammonium nitrogen by struvite precipitation, which were obtained at home and abroad in recent years. The mechanism and influence factors of struvite precipitation for ammonium nitrogen removal were discussed. Additionally, the problems that still should be resolved and the research directions in future were pointed out.
Authors: Wei Hua Song, Jun Yin, Jian Hui Wang
Abstract: A lab-scale study was conducted to precipitate the ammonia from high NH3-N concentration wastewater in the form of magnesium ammonium phosphate(MAP) by applying such chemicals such as MgCl2·6H2O and KH2PO4.The influences of pH value, reactive time and removal rate of ammonia nitrogen were tested.The results shows that the feasible pH values of crystallization and precipitation were between 8 and 10. The structure of struvite crystallization was destroyed under high pH value condition that resulted in ammonia nitrogen dissociating from MAP, which reduced the removal rate of ammonia nitrogen. Results also demonstrated that ammonia nitrogen was effectively reduced from initia1981mg/L to final 5 mg/L, which removal efficiency reached 99% with crystallization and precipitation method when the optimal pH, precipitation time mole ratio of Mg2+, NH4+, PO43- were 8.0, 20 min and 1.4∶1∶1.4 respectively.
Authors: Lei Wang, Fu Guo Qiu
Abstract: The urine-diverting toilet separates the urine and faeces and collects urine alone at the source. This technique can not only collect and make the most use of nutrients in urine, but also reduce the pollutants load on water bodies. Because of the valuable benefits of urine-source separation system, many researchers have done a lot of study in the global scope and obtained many results on this techniques. Currently studies focus on extracting struvite precipitation from urine which can synchronously recover nitrogen and phosphorus. Because phosphorus is a scarce resource and most phosphate resources are going to the bottom of sea. The recovery of struvite can realize the sustainable utilization of phosphorus resources. This paper reviews the latest research outcomes on urine diverting and treatment techniques.
Authors: S. Muryanto, A.P. Bayuseno
Abstract: Intensified agriculture in response to the growing population has led to excessive nutrient discharges to natural waters causing environmental problems in the form of eutrophication and its associated risks. Treatment options for this adverse effect include removal and recovery of soluble phosphorus by chemical precipitation, biological uptake, and struvite crystallisation. Chemical precipitation is the most common method due to its simplicity, but the chemical requirements can be prohibitive and the removed phosphorus is less reusable. Biological uptake requires less chemicals but the process is complex and prone to seasonal variations. Phosphorus removal and recovery from wastewater by struvite crystallisation is an attractive option since the crystallisation process converts phosphorus into struvite crystals, i.e. phosphate minerals which have proved to be good fertilizer, hence potentially reduces fertilizer production and the subsequent greenhouse gas emissions. Moreover, struvite crystallisation helps prevent scaling of wastewater treatment facilities. A number of struvite crystallisation projects utilising primarily agricultural wastewater is already operational at industrial scale.
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