强化混凝技术对南淝河季节性污染物去除效果研究

摘要

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 reached 99%. 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 MgCl2 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 was 24. 49% in the winter.%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MgCl2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%。