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21.
Simultaneous removal of phosphorus and potassium from synthetic urine through the precipitation of magnesium potassium phosphate hexahydrate 总被引:1,自引:0,他引:1
This study investigated the simultaneous removal of P and K from synthetic urine through the precipitation of magnesium potassium phosphate hexahydrate (MPP, MgKPO4·6H2O) in bench-scale experiments. Results show that the removal efficiencies of P and K are mainly determined by the solution pH and the molar ratio of Mg:K:P. Co-precipitation of struvite-type compounds, i.e., magnesium ammonium phosphate hexahydrate (MAP, MgNH4PO4·6H2O), magnesium sodium phosphate heptahydrate (MSP, MgNaPO4·7H2O), and MPP, was confirmed by analysis of the solid precipitates using a Scanning Electron Microscope/Energy Dispersive X-ray Apparatus and an X-ray Diffractometer. The co-precipitation significantly influenced the removal of K. As much ammonium as possible should be removed prior to MPP precipitation because MAP had higher tendency to form than MPP. The inevitable co-precipitation of MPP and MSP resulted in the addition of more MgCl2·6H2O and Na2HPO4·12H2O to obtain the high removal of K. In total, the removal efficiencies of P and K were 77% and 98%, respectively, in the absence of ammonium when pH was 10 and the molar ratio of Mg:K:P was 2:1:2. The results indicate that the MPP precipitation is an efficient method for the simultaneous removal of P and K to yield multi-nutrient products. 相似文献
22.
The establishment of nutrient cycles has been widely proposed as a strategy for an efficient management of nutrients such as phosphorus (P). Global reserves of phosphate rocks are limited and are being increasingly depleted. At the same time, P is disposed of via various substance-streams in wastewater treatment. Establishing nutrient cycles may solve these problems and lead to innovative added-value chains with a higher added-value. The objective of this paper is to assess the added-value of P-recovery from sewage sludge via struvite precipitation and its application as fertilizer in Berlin-Brandenburg (Germany). The added-value from struvite precipitation was determined by performing a cost/benefit analysis based on data from standardized questionnaires and interviews with operators of wastewater treatment facilities. Surveys of 146 farmers were used to ascertain what crops were cultivated in the study area and to gauge the willingness of farmers to substitute struvite for conventional mineral P-fertilizer. Benefits from using struvite were found by calculating the fertilizer costs when struvite is substituted for conventional mineral fertilizer. The results indicate that the precipitation of struvite and its use as fertilizer generates added-value gains for wastewater treatment facilities (416,000 €) and for crop producers (35,000 €). In wastewater treatment, struvite precipitation reduces operating costs and yields additional revenues through struvite sales. In crop production, fertilization costs are reduced by substituting struvite for mineral P-, N- and Ca-fertilizers. The distribution of the added-value in the struvite value chain is determined by the marketing strategy of struvite. Farmers may obtain a higher share of added-value if struvite is marketed via direct sale. 相似文献
23.
Zhi-Long Ye Yujun Deng Yaoyin Lou Xin Ye Shaohua Chen 《Frontiers of Environmental Science & Engineering》2018,12(3):7
24.
The simultaneous removal of K and P from urine for nutrient recycling by crystallization of magnesium potassium phosphate hexahydrate (MPP) in a laboratory-scale draft tube and baffle reactor (DTBR) is investigated. Results show that mixing speed and hydraulic retention time are important operating factors that influence crystallization and crystal settlement. Slurry should be discharged at a crystal retention time of 11 h to maintain fluidity in the reactor. Further applications of the DTBR using real urine (pretreated by ammonia stripping and diluted five times) showed that 76% K and 68% P were recycled to multi-nutrient products. The crystals collected were characterized and confirmed mainly as a mixture of magnesium ammonium phosphate hexahydrate, MPP, and magnesium sodium phosphate heptahydrate. Results indicate that the DTBR effectively achieved the simultaneous recycling of K and P from urine to multi-nutrient products through MPP crystallization. 相似文献