混凝沉淀法处理低含磷废水实验研究

Experiments on Removal of Low P Content Wastewater by Coagulation Method

城市污水处理厂二级出水中含磷浓度较低,要达到回用标准仍需进一步去除。利用FeCl3、FeSO4、Al2(SO4)3 和聚合氯化铝(PAC)四种混凝剂在室温条件下对含磷浓度为1．2mg/L的城市污水处理厂出水进行混凝处理,寻找最佳处理效果的投药量和pH值。实验表明,欲使处理后出水总磷浓度达到地表水环境质量标准Ⅲ类水质标准,FeCl3 的最佳投药量为30mg/L,最佳pH为7．24-9．00;Al3(SO4)3的最佳投药量为50mg/L,最佳pH为6．92-8．04;PAC的最佳投药量为30mg/L,最佳pH为7．24-7．94,而FeSO4对磷的去除效果较差,当投药量达70mg/L时,去除率仅为23．33％。

Although phosphate concentration in the secondary effluent of sewage treatment plant is low, the phos-phate concentration should be decreased further if it is wanted to keep compliance with quality of the reuse water standard. Low P content waste water with P of 1.2mg/L was treated by coagulation using 4 kinds of coagulant： FeCO3.FeSO4.Al2（SO4）3 and polyaluminum chloride（PAC）. In order to find the optimum coagulant dosage and pH to make the treated wa-ter in accordonce with the quality of Ⅲ category surface water of the standard GB3838-2002. The experimental results in-dicated that the optimum pH and dosage are 7.24-9.00 and 30mg/L with Fecl3 used as coagulant, 7.24-7.90 and 30mg/L with PAC,6.92-8.04 and 50mg/L with Al2（S04）3. When FeSO4 is used and it＇s dosage increased to 70mg/L, the removalrate of P is only 23,33%.