强化混凝技术对南淝河季节性污染物去除效果研究

Study on removal efficiency of enhanced coagulation technology for treatment of seasonal pollutants from Nanfeihe River

针对南淝河河口水体夏秋季节藻类的质量浓度高,冬季NH_4^+-N质量浓度异常高的特点,研究强化混凝技术对藻类和NH_4^+-N的去除效果,并应用于南淝河现场构建的混凝沉淀系统。结果表明:混凝剂单独使用时,聚合氯化铝(poly aluminium chloride,PAC)的除藻效果最好,去除率为76%。选用除藻效果较好的阳离子聚丙烯酰胺(cationic polyacrylamide,CPAM)作为助凝剂,藻类的去除率显著增加,均达99%,但对NH_4^+-N的去除效果不佳;聚合氯化铝铁(poly aluminium ferrous chloride,PAFC)与CPAM的组合对NH_4^+-N的去除率最高,为7.54%。通过投加黏土矿物,增加NH_4^+-N的去除率。NaCl与MgCl_2联合改性的凹凸棒与CPAM联用时,对NH_4^+-N的去除率最高达85.65%。选用"PAFC+CPAM"作为南淝河旁路强化混凝系统的投药配方,现场应用时,夏秋季对藻类的去除率平均为88.64%;冬季对NH_4^+-N的去除率平均为24.49%。

Algae in the estuary of the Nanfeihe River show high concentrations in the summer and autumn,and the concentration of NH_4~＋-N is extremely high in the winter. Based on these characteristics,we studied the efficiency of the enhanced coagulation technology in removing algae and NH_4~＋-N,and applied this technology to an on-site coagulation and sedimentation system by the river. The results show that polyaluminum chloride（ PAC） had the highest removal rate（ 76%） of algae when the coagulants were applied alone; the removal rate increased markedly when cationic polyacrylamide（ CPAM） was applied as coagulant aid and the removal rates of algae all reached99%. However,they had little effect on the removal of NH_4~＋-N. Joint use of polyaluminum ferric chloride（ PAFC）and CPAM had the highest removal rate（ 7. 54%） of NH_4~＋-N. Clay mineral was also chosen to increase the removal rate of NH_4~＋-N. The attapulgite modified by NaCl and MgCl_2 was used in combination with CPAM,and the removal rate of NH_4~＋-N reached 85. 65%. PAFC ＋ CPAM was selected as a pharmacy prescription used in the on-site coagulation system. The mean removal rate of algae was 88. 64% in the summer and autumn and that of NH_4~＋-N was24. 49% in the winter.