粉末碳与污泥回流强化混凝低温低浊水及残余铝

Enhanced coagulation by recycling sludge on pollutants removal and residual aluminum species for treating low turbidity and low temperature water

研究了粉末活性碳与聚铝混合污泥回流强化混凝对浊度、UV254和DOC去除效能;同时考察了回流对各种形态铝质量浓度的影响.结果表明,当聚合氯化铝和粉末炭的投加量分别为10、20 mg/L,粉末活性炭-聚铝混合污泥回流量为60 mL/L(回流比6%),pH值为8时,浊度去除率最大为78.5%;pH值为6.5～7.0时,DOC和UV254的最大去除率分别达29.6%和53.3%.回流工艺能强化去除浊度和有机物主要是由于回流污泥中不溶性金属氢氧化物的架桥和卷扫作用,以及回流污泥中和预投加PAC最大限度的吸附作用.回流污泥中的Al主要以颗粒形式粘附于絮体上,回流沉后水总余铝质量浓度高于常规工艺,但溶解态铝质量浓度均满足GB2006-2597生活饮用水卫生标准(<0.2mg/L).

In this paper, the effect of powdered activated carbon （PAC） and polyaluminum chloride （PAC1） mixed sludge recycled volume （recycling ratio）, solution pH on coagulation performance i.e. turbidity, UV254 and DOC removal, as well as residual aluminum species were investigated. The results indicated that the effective turbidity removal could be obtained by recycling 60 mL mixed sludge, when pH was 8.0, the additive dosage of PAC1 was 10 mg/L and that of PAC was 20 mg/L. Inversely, DOC and UV254 removal were higher in weak acid range 6.5 - 7.0 than that at basic pH range, which could be reached up 29.6% and 53.3% respectively. The enhancement of NOMs and particulates removal efficiencies were mainly attributed to sweep flocculation and adsorption by PAC in sludge and fresh ‘ preloaded＇. The aluminum species in recycled sludge was in the form of granule attached to the flocs, which could be easily separated and deposit to the bottom of sedimentation tank. The residual total alum contents in settling water were more than that in conventional coagulation,but the dissolved alum concentrations met the requirements of standards GB2006 - 2597 （ 〈 0.2 mg/L）.