接枝型阳离子淀粉絮凝剂在污泥脱水中的应用与机理研究  

Application and mechanism of a graft cationic starch-based flocculant in sludge dewatering

作　　者：陈炜 沈少航 闵广宇 陈润泽 胡潘 魏华 杨琥[1] CHEN Wei;SHEN Shaohang;MIN Guangyu;CHEN Runze;HU Pan;WEI Hua;YANG Hu(State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing,210023,China)

机构地区：[1]南京大学环境学院,污染控制与资源化研究国家重点实验室,南京210023

出　　处：《环境化学》2021年第7期2217-2225,共9页Environmental Chemistry

基　　金：国家自然科学基金(51978325)资助.

摘　　要：混凝/絮凝是目前污水处理厂普遍采用的一种经济有效的污泥调理技术。针对传统混凝剂/絮凝剂存在的安全隐患问题,本文以来源广泛、廉价易得的一种天然高分子——淀粉为原材,采用醚化反应及接枝共聚技术,分别以3-氯-2-羟丙基三甲基氯化铵(CTA)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为醚化剂及接枝共聚单体,制得一系列不同DMC取代度及电荷密度的接枝型阳离子改性淀粉絮凝剂(St-CTA-g-PDMC)。以南京某市政污水厂活性污泥为研究对象,测定不同St-CTA-g-PDMC样品调理后的污泥比阻与泥饼含水率,结合污泥内胞外聚合物(EPS)形态及组成含量变化,详细讨论了St-CTA-g-PDMC中DMC取代度及电荷密度对污泥脱水性能影响。研究结果表明,St-CTA-g-PDMC具有良好的污泥调理效果;St-CTA-g-PDMC的DMC取代度及电荷密度是影响絮凝剂脱水性能的重要因素,DMC取代度及电荷密度越高污泥脱水效果越佳,电中和及粘结架桥作用是污泥脱水的主要机制。调理后污泥中溶解态与松散结合态EPS中蛋白质与多糖含量下降,这是由于St-CTA-g-PDMC结合并压缩EPS,有效破坏EPS结构并释放结合水。综上,St-CTA-g-PDMC制备方法安全简便,具有良好的污泥调理效果,其在污泥脱水中应有着广阔的应用前景。Coagulation/flocculation is one of the most extensive and cost-effective pretreatments to improve the dewaterability of sludge in wastewater treatment plants.In view of the potential pollution risks existing in traditional coagulants/flocculants,a series of graft cationic starch(St)-based flocculants(St-CTA-g-PDMC)with different charge densities(CD)and substitution degrees were synthesized by etherification and graft copolymerization in this study.3-Chloro-2-hydroxypropyltrimethylammonium chloride(CTA)and(2-methacryloyloxy-ethyl)trimethyl ammonium chloride(DMC)were used as etherifying agents and graft monomers,respectively.Taking the activated waste sludge obtained from a municipal wastewater treatment plant in Nanjing as the research object,the dewatering performance of St-CTA-g-PDMC were investigated in detail by combination with the analysis of the changes in filter cake moisture content,specific resistance of filtration,and extracellular polymeric substances(EPS)fractions and components in the dewatering process.These graft St-based flocculants,with the structural characteristics of high CD and high degree of DMC substitution,exhibited superior dewaterability of sludge because of the enhanced charge neutralization and bridging flocculation effects.Besides,the contents of protein and polysaccharide in soluble EPS and loosely-bound EPS decreased after conditioned by St-CTA-g-PDMC,because these St-based flocculants can combine and compress EPS in sludge,destroy EPS structures and release binding water efficiently.St-CTA-g-PDMC,with the characteristics of environmental-friendliness,simple preparation,and good dewatering performance,may thus have notable application potentials in sludge dewatering.

关 键 词：阳离子接枝改性淀粉絮凝剂 电荷密度 污泥脱水 胞外聚合物 污泥脱水机制 

分 类 号：X703[环境科学与工程—环境工程]