用混凝及污泥回流处理二沉池出水的研究

Treatment of Effluent from Secondary Sedimentation Pool by Coagulation and Sludge Returning Method

选择液体用聚合氯化铝（PAC）作为混凝剂，对二沉池出水进行了混凝及污泥回流实验，考察了pH值、PAC用量、污泥回流量等因素对处理效果的影响。结果表明，当废水pH值为6．5～8．2、PAC用量3mL／L、污泥回流率40％～60％时，处理效果明显优于传统混凝方式，CODCr由400mg／L降至100mg／L左右。

The effluent form secondary sedimentation pool in paper mill＇s waste water treatment system was further treated by coagulation using PAC as flocculant and returning part of the sludge back to the system. The influences of pH value of wastewater, the adding amount of flocculent and return sludge flow were investigated. The results showed that the appropriate pH value is from 6.5 to 8.2, the adding amount of PAC is 3 mL/L, and the appropriate return sludge is from 40% to 60%. The effect of treatment is more significant than the traditional coagulation. The concentration of CODCr falls from 400 mg/L to 100 mg/L after the treatment.