磷酸铵镁结晶法去除和回收养猪废水中营养元素的实验研究

Nutrient removal and recovery from swine wastewater by crystallization of magnesium ammonium phosphate

以模拟养猪废水为处理对象,进行了磷酸铵镁结晶小试实验,考察了pH值、NH4^＋、Mg^2＋、Ca^2＋和CO3^2-浓度对磷酸铵镁结晶反应的影响;利用扫描电镜-能谱分析仪（SEM-EDX）和X射线衍射仪（XRD）对结晶产物进行了表征.结果表明,磷酸铵镁结晶反应的最佳pH值范围为9.5～10.5;随着NH4^＋与磷摩尔比的增加,磷的去除率增大;最佳的镁与磷的摩尔比为1.4：1,过高的镁盐投加量对提高反应效率作用不明显;Ca^2＋的存在对磷酸铵镁结晶产物的晶形、纯度均产生干扰,当Ca2＋增至一定浓度时,反应将生成无定形的磷酸钙沉淀;CO3^2-的存在会降低磷的去除率,但不影响磷酸铵镁的晶形与纯度.

Using synthetic swine wastewater, small-scale batch experiments were carried out to investigate the effects of pH, ammonium nitrogen concentration, magnesium （Mg） dosage, calcium （Ca） and carbonate （CO3^2-） concentrations on magnesium ammonium phosphate （MAP） crystallization. The morphology of the crystals obtained was observed with Scanning Electron Microscopy with Energy Dispersive X-ray analysis （SEM- EDX）, and the composition of the crystals was analyzed by X-ray Diffraction （ XRD）. The results show that the optimum pH value for MAP crystallization is in the range of 9.5 - 10.5 ; the P removal efficiency increases with the increase of N：P molar ratio ; the optimum Mg：P molar ratio is 1.4：1. Excessive Mg dosage does not have an obvious effect on the efficiency of MAP crystallization. The presence of Ca disturbs the morphology and purity of the MAP product. Amorphous calcium phosphate will form when Ca reaches a high enough concentration. CO3^2- affects P removal efficiency, but does not obviously affect the morphology and purity of MAP.