酸性条件下剩余污泥中Ca2+和Mg22++溶出对磷回收的影响
Impacts of Ca2+ and Mg2+ release on phosphorus recovery in excess sludge under acidic condition
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摘要: 为了在酸性条件下实现剩余污泥中磷的高效回收，对pH=3时剩余污泥水解酸化过程中氨氮、正磷酸盐和钙镁离子的溶出现象以及磷回收进行了研究分析。结果表明：当pH=3时，所溶出的氨氮、镁离子和钙离子与磷酸盐的摩尔比均大于1，能满足采用鸟粪石沉淀法或者羟磷灰石沉淀法回收磷的要求；但所溶出的钙镁离子的摩尔比大于1，会对鸟粪石沉淀法回收磷的顺利进行有较大影响；有无外加镁剂对磷回收率影响不大。采用改型后的镁型强酸性阳离子交换树脂进行离子交换可以得到较高纯度的鸟粪石沉淀产品，通过XRD检测其纯度为95%以上。Abstract: To study the impact of release of calcium and magnesium ions in excess sludge under acidic condition on phosphorus recovery， release process of ammonia-nitrogen， phosphate and calcium and magnesium ions at pH=3 and phosphorus recovery process were discussed. The results shows that at pH=3，all the molar ratios of ammonia， magnesium and calcium ions dissolved to phosphate were greater than 1， which could meet the requirements of phosphorus recovery by means of struvite precipitation or hydroxyapatite precipitation.Molar ratio of calcium and magnesium ions dissolved was also greater than 1， which would have a serious influence on phosphorus recovery by the method of struvite precipitation.Whether additional magnesium existed or not had little effect on the percent recovery of phosphorus. It is feasible to choose strongly acidic cation exchange resin modified with magnesium to ion exchange for improving the quality of the precipitation products. It is determined that precipitation products contain more than 95% of struvite by chemical analysis and XRD detection.
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