Department of Chemical & Materials Engineering, University of Auckland, Auckland 1010, New Zealand.
Department of Chemical & Materials Engineering, University of Auckland, Auckland 1010, New Zealand.
J Environ Sci (China). 2022 Mar;113:81-91. doi: 10.1016/j.jes.2021.05.038. Epub 2021 Jun 18.
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 economic feasibility of this process is highly dependent on the cost of magnesium source. Two different magnesium sources were used for phosphorus recovery: pure magnesium chloride 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. Experimental design with five numerical variables (Mg/P molar ratio, pH, PO-P, NH-N, and Ca 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 analysis (PCA). Results indicated that a magnesium source obtained from NF retentate was as effective as MgCl for struvite precipitation. It was also revealed that ionic strength had a more positive effect on struvite 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.
全球磷矿储量的减少促使人们对探索替代磷资源产生了浓厚的兴趣。本研究通过沉淀鸟粪石（一种有价值的缓释肥料）从猪废水中回收磷。该过程的经济可行性高度依赖于镁源的成本。本研究使用了两种不同的镁源进行磷回收：纯氯化镁和纳滤（NF）盐水浓缩液。本文重点研究了离子强度对磷回收性能的影响，这在其他地方尚未有报道。采用具有五个数值变量（Mg/P 摩尔比、pH 值、PO-P、NH-N 和 Ca 水平）和一个分类变量（镁源类型）的实验设计来评估离子强度对磷去除和鸟粪石纯度的影响。使用方差分析（ANOVA）和主成分分析（PCA）对实验数据进行分析。结果表明，NF 浓缩液中的镁源与 MgCl 一样有效用于鸟粪石沉淀。研究还表明，离子强度对鸟粪石纯度的影响比对磷去除的影响更为积极。在本研究中研究的参数范围内，高离子强度、高 pH 值以及富磷、高铵和低钙的废水被认为是最有利于鸟粪石沉淀的条件。本研究的结果将有助于确定使用高离子强度的盐水（如 NF 海水浓缩液）作为富含铵氮和磷酸盐的废水的镁源回收磷的可行性。
