KMnO4与PAC联用强化混凝处理西北村镇集雨窖水研究

Application of enhanced coagulation by potassium permanganate combined with powdered activated carbon on the cellar rainwater treatment of northwest region villages and small towns

针对西北村镇集雨窖水含浊、低温、微污染,采用常规混凝工艺效果不佳的情况,通过试验考察了单独采用高锰酸钾预氧化、单独投加粉末活性炭以及高锰酸钾与粉末活性炭联用3种工艺对常规混凝的强化效果,并对影响强化混凝效果的高锰酸钾和粉末活性炭不同投加量和投加顺序进行试验研究。结果表明:KMnO_4与PAC联用具有最佳的强化混凝效果,在常规混凝的最佳条件下,当KMnO_4的最佳投量为2 mg·L^(-1),预氧化时间为15 min,而PAC的最佳投量为10mg·L^(-1),并且在投加混凝剂后3 min投加,则经强化混凝后的窖水浊度和COD_(Mn)的去除率可达98.5%和56.6%;两者联用具有协同增效作用。

The aim of this study is to solve the issue of unsatisfactory treatment of cellar rainwater with conventional coagulation process which was caused by characteristics of little turbidity, lower temperature and presence of micro-pollutants for the villages and small towns of China＇s northwest region. The removal efficiencies of three coagulation processes, including potassium permanganate （KMnO4） dosing solely, powdered activated carbon （PAC） dosing solely as well as the combination of potassium permanganate and powdered activated carbon were investigated. Meanwhile, different dosage and adding sequence of potassium permanganate and powdered activated carbon were also tested under similar processes. The static test results show that the treatment process of potassium permanganate combined with powdered activated carbon is the best solution for enhanced coagulation. Initially, the best condition of conventional coagulation was found as follows： the poly-aluminum and ferric chloride（PAFC） dosage was 60 mg·L^-1,the mixed-stirring time was 0.5 minute with the rate of 300 r·min-1 , the flocculation-stirring time was 10 minutes with the rate of 100 r·min-1 and the settling time was 15 minutes. When the optimal dosage of KMnO4 was 2 mg·L^-1 and preoxidation time was 15 minutes accompanying with the optimal dosage of PAC （10 mg·L^-1） added in 3 minutes after coagulant dosing, the removal rates of cellar rainwater turbidity and CODMn were 98.5% and 56.6%, and the rates were 12.1% and 22.5% higher than those of conventional coagulation. It was noteworthy that synergy presented between KMnO4 and PAC in the removal of organic matter. With this process, the removal rate of CODMn was found 11% and 8.8% higher than that of KMnO4 dosing solely and PAC dosing solely. The treatment process of KMnO4 combined with PAC was an ideal process for cellar rainwater treatment in northwest region villages and small towns.