污水处理厂回流液中回收磷酸铵镁的试验研究

用污水处理厂回流液进行磷酸铵镁(MAP)沉淀试验,研究化学沉淀法回收MAP的适宜条件.结果表明,pH为8～11时生成沉淀的主要成分为MAP;当pH为10,药剂配比n(NH+4)∶n(Mg2+)∶n(PO43-)控制在1∶1∶1和1∶1.4∶1时得到的晶体纯度高,前者形成的沉淀量为5.3 g/L,氨氮去除率为90.86%;后者形成的沉淀量为5.74 g/L,氨氮去除率为95.84%.分析表明从回流液中回收MAP可以大幅降低处理成本以及系统的氮磷负荷,还可解决MAP结垢问题,实现资源的再生.

Study on Recovery of Magnesium Ammonium Phosphate from Return Flow in Wastewater Treatment Plant

Batch experiments of MAP precipitation were conducted to examine the optimal conditions of MAP recovery with return flow in the wastewater treatment plant as samples. The results indicated that the precipitate was MAP when pH was maintained between 8. 0 and 11. 0, and the precipitate had high purity and the yield could attained 5. 3 g/L or 5. 47 g/L when pH was maintained at 10 and the ratio of n(NH4+) : n(Mg2+) :n(PO43-) was 1 : 1 : 1 or 1 : 1. 4 : 1, the removal rate of NH3+ -N can be reached 90. 86% or 95. 84%. Analysis showed the cost of treatment and the nitrogen and phosphorus load of system could be dropped greatly, the trouble of MAP scale could be removed because of MAP recovery from return flow, and the reclaiming of resources could be realized.