混凝-沉淀-砂滤工艺对污水中典型医药类物质的去除特性研究

Study on removal characteristics of typical pharmaceutical substances in wastewater treated by coagulation, precipitation and sand filtration

通过实验室模拟的混凝-沉淀-砂滤装置,研究混凝剂聚合氯化铝(PAC)、聚合硫酸铁(PFS)和絮凝剂聚丙烯酰胺(PAM)投加量和投加方式对污水中医药类物质降固醇酸(CA)、卡马西平(CBZ)、萘普生(NAP)和双氯芬酸(DCF)的去除特性.研究发现,针对医药类物质总进水浓度2 mg/L的污水厂二级出水,单独投加PAC 60 mg/L下混凝-沉淀-砂滤工艺对医药类目标物的去除效果最佳,总去除率为30.31%,去除顺序为CBZ>DCF>CA>NAP;PFS单独投加量100 mg/L下的去除效果最好,目标物总去除率为28.96%,去除率大小是DCF>CA>CBZ>NAP.PAC或PFS主要通过电性中和的方式来消除医药类物质所带电荷,从而使其吸附凝聚于脱稳胶体和细微悬浮物上而被分离除去.少量PAM与PAC同时投加时医药类物质的去除效果明显提高,PAM的吸附桥联作用促进了絮体的联结沉降和目标化合物的吸附去除.PAC和PFS的同时投加可增强NAP的有效去除,但两者的交互作用需通过投加量和配比的优化来实现.医药类物质主要是通过混凝-沉淀得以去除,砂滤的去除效果微小,有时甚至为零.

Removal characteristics of pharmaceutical compounds in wastewater, clofibric acid（CA）, carbamazepine（CBZ）, naproxen（NAP） and diclofenac（DCF） were investigated by the change of dosage and dosing mode of poly aluminium chloride（PAC）, polymeric ferric sulfate（PFS） and polyacrylamide（PAM） through an experimental setup of coagulation, precipitation and sand filtration. The research indicated that removal efficiencies of four target pharmaceuticals reached 30.31% in total initial concentration of 2 mg/L and PAC dosage of 60 mg/L, and the sequence of removal rate was CBZ〉DCF〉CA〉NAP. The best removal rate was up to 28.96% for PFS with the dosage of 100 mg/L, and the order of removal rate was DCF〉CA〉CBZ〉NAP.Negative charges of target compounds can be neutralized by Al3＋ or Fe3＋ from PAC or PFS so that pharmaceutical substances are easily adsorbed onto the destabilized colloid and suspended microparticles, which could be removed in the process of precipitation and sand filtration. Removal efficiencies of pharmaceutical substances were improved obviously in the presence of PAC and PAM with dosage of 0.5 mg/L, which was due to adsorption and bridge effect of PAM. The removal of NAP was improved at dosing PAC and PFS simultaneously. However, the interaction effect between PAC and PFS needs to be optimized by the adjustment of their dosage and proportion. Coagulation and precipitation played important roles in the removal of pharmaceutical substances in wastewater, and the sand filtration was of little or sometimes even no effect in experiment.