【摘 要】
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Declining worldwide phosphate rock reserves has driven a growing interest in exploration of alternative phosphate supplies.This study involved phosphorus recovery from swine wastewater through precipitation of struvite,a valuable slow-release fertiliser.T
【机 构】
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Department of Chemical & Materials Engineering,University of Auckland,Auckland 1010,New Zealand
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Declining worldwide phosphate rock reserves has driven a growing interest in exploration of alternative phosphate supplies.This study involved phosphorus recovery from swine wastewater through precipitation of struvite,a valuable slow-release fertiliser.The eco-nomic feasibility of this process is highly dependent on the cost of magnesium source.Two different magnesium sources were used for phosphorus recovery:pure magnesium chlo-ride and nanofiltration (NF) saline water retentate.The paper focuses on the impact of ionic strength on phosphorus recovery performance that has not been reported elsewhere.Ex-perimental design with five numerical variables (Mg/P molar ratio,pH,PO43-P,NH4+-N,and Ca2+ levels) and one categorical variable (type of magnesium source) was used to evaluate the effect of ionic strength on phosphorus removal and struvite purity.The experimental data were analysed using analysis of variance (ANOVA) and principal component analy-sis (PCA).Results indicated that a magnesium source obtained from NF retentate was as effective as MgCl2 for struvite precipitation.It was also revealed that ionic strength had a more positive effect on stmvite purity than on phosphorus removal.Within the range of parameters studied in this research,high ionic strength,high pH and wastewater with high phosphate,high ammonium and low calcium contents were found to be the most favourable conditions for struvite precipitation.Findings from this study will be beneficial to determine the feasibility of using high ionic strength saline water,such as NF seawater retentate,as a magnesium source for phosphorus recovery from wastewater that is rich in ammonium-nitrogen and phosphate.
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