某城市污水处理厂废水化学除磷沉淀特性及影响因素

通过对西安市某污水处理厂进水、厌氧池上清液、二沉池出水、污泥浓缩水、污泥脱水进行FeCI3·6H2O、PAC除磷实验,并以FeCI3·6H2O为沉淀剂对厌氧池上清液从pH、Fe/P摩尔比、腐殖酸、挥发性脂肪酸(VFA)等因素进行批次实验分析磷去除状况.实验显示,三氯化铁、PAC对进水除磷效果不佳,厌氧池上清液用FeCI3·6H2O为沉淀剂时磷去除率较低,二沉池出水、污泥浓缩水以及污泥脱水用FeCI3·6H2O、PAC时其正磷去除率均可达到80%左右.通过对比不同pH值、Fe/P摩尔比、腐殖酸和VFA浓度对厌氧池上清液除磷效果的影响,结果表明,在pH=4~5,Fe/P=1.3时磷的去除效果达到78%以上,腐殖酸浓度对磷去除率影响不大,VFA在低于10 mg/L和高于60 mg/L时对磷去除率影响较大.

Characteristics of chemical phosphorus precipitation of wastewaters from a municipal sewage treatment plant and its influencing factors

Characteristics of chemical phosphorus precipitation of raw water, effluent from the secondary treatment unit, supernatant of anaerobic tank, effluent from sludge concentration tank and rejected wastewater from sludge dewatering of a municipal sewage treatment plant in Xi'an were investigated using FeCI3·6H2O and PAC as precipitant. The influences of pH, Fe/P molar ratio, humic acid and volatile fatty acid(VFA) on the chemical phosphate removal of supernatant of the anaerobic tank were investigated. The results showed that the FeCI3·6H2O and PAC were not suitable for chemical phosphate removal on raw water. The phosphate removal rate of the anaerobic supernatant is low with FeCI3·6H2O, and the phosphate removal rate of the secondary effluent, the effluent of the sludge dewatering and sludge concentration tank is about 80% with FeCI3·6H2O and PAC. Through different pH, Fe/P molar ratios, humic acid and VFA on anaerobic supernatant phosphorus removal, the results showed that the phosphorus removal was more than 78% at pH=4~5 and Fe/P=1.3, the humic acid had little effect on the phosphate removal, there was a great effect on the phosphate removal rate when the VFA was less than 10 mg/L and more than 60 mg/L.