不同形态铁盐的除磷效果

研究不同铁盐存在形态的铁盐类混凝剂,即三氯化铁(离子态铁)、聚合氯化铁(聚合态铁)和氢氧化铁(凝胶态铁),在混凝除磷性能方面的差异。以城市污水厂的二级出水为实验水样,进行混凝除磷性能研究。结果表明,二级出水总磷为1.74 mg/L,离子态铁投加量为40 mg/L时,对总磷的去除率为90%,混凝处理后上清液总磷可达《城镇污水处理厂污染物排放标准》(GB18918-2002)中的一级A标准,聚合态铁对总磷的去除率为62%,凝胶态氢氧化铁的总磷去除率为59%,混凝处理后上清液总磷均不能满足GB18918-2002中的一级A标准。离子态氯化铁对污水厂二级出水的除磷效果优于聚合态,即铁离子的聚合形态会影响其除磷效果。

Effects of different forms of ferric salt on phosphorus removal

The efficiency of phosphorus removal of ferric chloride (ionic state),polyferric chloride (polymer state) and ferric hydroxide (gel state) from the effluent of municipal sawage treatment plant was studied.Total phosphorus (TP) in the effluent was 1.74 mg/L.The results showed that ferric chloride was the best among the three forms of ferric salt coagulants.When the dosage of ferric chloride was 40 mg/L,the phosphorus removal rates could reach 90%,and TP in the treated wastewater was less than 0.17 mg/L.The effluent quality could meet the first level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).The phosphorus removal rates of polyferric chloride and ferric hydroxide were 62% and 59%,respectively,with 40 mg/L of coagulants.