磷酸铵镁沉淀法回收猪场废水中氮磷的中试研究

A Medium-Scalestudy of Recovery of Nitrogen and Phosphorus by Struvite Crystallization from Swine Wastewater

针对猪场废水传统脱氮除磷生物处理工艺中碳源不足、氮含量过高等问题,采用磷酸铵镁(MAP)结晶法回收猪场废水中的部分氮、磷,目的在于提高废水中碳氮比,为后续生物处理奠定基础.在选择投加MgCl2.6H2O和Na3PO4.12H2O为镁源和磷源时,试验结果表明:MAP法回收猪场废水中氮磷的最优反应条件为n(Mg)∶n(N)∶n(P)=1.2∶1∶0.9;此条件下回收的沉淀物中N的含量约4.1%,P2O5的含量约40.77%,MgO的含量约15.85%,是一种高品质缓释性肥料;经回收后的废水pH能维持在8.5左右,n(BOD5)∶n(N)∶n(P)=95∶5∶1,余氮浓度在170 mg/L左右,余磷浓度在20 mg/L左右,适合用生物法继续处理.

In view of the problems of shortage of carbon source and excess of nitrogen content in traditional ni- trogen and phosphorus removal, this paper adopts the method of magnesium ammonium phosphate （MAP） crystallization to recover a part of N and P to increase the ratio of carbon to nitrogen, which is beneficial for following biological treatment. The results show that the optimal reaction condition, the molar ratio of n（Mg） ： n（N）： n（P） = 1.2： 1：0.9, was obtained through single factor experiment when choosing MgC12 · 6H_O Na_3 PO_4 · 12H_20 as magnesium source and phosphorus source. In this condition, the content of N, P205 and MgO of the sediment, slow-release organic fertilizer, recovered is 4.1% , 40.77% and 15.85% , respectively. Af- ter recovering, the pH of the wastewater is about 8.5, the ratio of n（ BOD5 ） ： n（N） ： n（P） almost 95： 5： 1, the concentration of residual nitrogen and phosphorus approximately 170 mg/L and 20 mg/L,it can be reduced by with by microorganism treatment.