复合混凝在去除清淤底泥余水中溶解性有机质的应用研究

Application of Composite Coagulation in Removal of Dissolved Organic Matter in Dredged Sediment

为揭示复合混凝对湖泊底泥中溶解性有机质(DOM)的去除机制,以白洋淀清淤底泥余水中DOM为研究对象,以聚合氯化铝(PAC)为混凝剂、聚丙烯酰胺(PAM)和聚二甲基二烯丙基氯化铵水溶液(HCA)为助凝剂,分体系探究复合混凝对余水中DOM的去除作用。结果表明:两种混凝体系对DOM的去除效率没有明显差异,当PAM为4mg/L,PAC为35mg/L时PAM助凝体系对COD去除率最大达86.6%,HCA为1.0mg/L时,PAC为35mg/L时HCA助凝体系对COD去除率最大达83.9%;在混凝时,DOM中共轭键及杂原子中未成键电子区域同絮凝剂作用,活性中心分布不均且敏感性不强;复合混凝后,DOM中芳香类蛋白、类富里酸组分得到有效的去除;复合混凝对DOM相对分子质量小于50Da的小分子组分有较好的去除效果;通过调节PAC投加量可控制DOM脱稳情况进而影响DOM的去除效果。

In order to reveal the removal mechanism of Dissolved Organic Matter(DOM)in dredged sedi-ment by composite coagulation,taking the DOM in dredged sediment in Baiyangdian Lake as the research object,this paper uses polyaluminum chloride(PAC)as coagulant,and polyacrylamide(PAM)and poly(two diallyl ammonium chloride ammonium chloride)(HCA)as coagulant aids to study the removal of DOM during composite coagulation.The resuls indicate that there is no obvious difference in DOM removal efficiency via those two systems.More specifically,when PAM and PAC are 4mg/L and 35mg/L,the ma-ximum removal efficiency of COD is 86.6%;when HCA and PAC are 1.0mg/L and 35mg/L,the maxi-mum removal efficiency of COD is 83.9%.During coagulation,the conjugated bond and non-bonded elec-tron region of heteroatom in DOM interact with flocculant,with the active center being unevenly distributed and weak sensitivity.After coagulation,aromatic protein and fulvic acid like components are removed to a certain extent;the coagulation process exhibits better performance in smaller molecular weight compo-nents,especially for the components with relative molecular weight less than 50Da.In addition,PAC do-sage could affect the DOM removal via controlling the destabilization of DOM.