铝、铁、钛3种金属盐基混凝剂调理污泥的性能比较

以铝盐、铁盐和钛盐混凝剂为研究对象,重点比较了3种混凝剂的污泥调理性能.通过测定调理前后污泥比阻、胞外聚合物中蛋白质和多糖的含量变化,结合三维荧光光谱与分子量变化分析及调理前后污泥尺寸大小与颗粒表面形貌变化,系统比较了它们对污泥的调理性能,并揭示了调理机制.3种无机混凝剂的污泥调理能力依次为:聚合氯化铝(PAC)、钛凝胶混凝剂(TXC)、聚合硫酸铁(PFS);调理后,污泥胞外聚合物中蛋白质和多糖含量明显降低;PFS和TXC对有机物的结合能力要强于PAC,疏松结合的胞外聚合物中多糖含量是影响污泥脱水性能的关键因素;调理过程中3种混凝剂所形成污泥颗粒的大小顺序为:TXCPFSPAC,所形成污泥颗粒的大小并非影响污泥脱水性能的关键因素,无机混凝剂电中和能力和与有机物的络合能力共同影响无机混凝剂的污泥调理性能.本研究为污泥调理混凝剂的选取提供了实验和理论依据.

Sludge Conditioning Performance of Polyaluminum, Polyferric, and Titanium Xerogel Coagulants

The sludge conditioning performance of inorganic Al, Fe, and Ti coagulants were systematically compared in terms of specific resistance to filtration (SRF), the content of protein and polysaccharide in extracellular polymeric substances (EPS), the change in three-dimensional excitation emission matrix fluorescence (3D-EEM), the molecular weight of organic matter in EPS, and the floc size and surface morphology. The sludge conditioning ability and the mechanism were systematically analyzed. The results showed that the sludge conditioning ability of the three inorganic coagulants was in the order of polyaluminum chloride (PAC) > titanium xerogel coagulant (TXC) > polymeric ferric sulfate (PFS). After conditioning, the contents of protein and polysaccharide in the EPS were greatly reduced, especially in the loosely bound EPS (LB-EPS). The combined capacity for coagulation between TXC/PFS and organic matter was stronger than that of PAC. The content of polysaccharide in LB-EPS was the key factor affecting the sludge dewatering performance but not the coagulated floc size. The surface charge and the chelating ability with organic matter co-determined the sludge dewatering ability. The organic cationic polymer, polyacrylamide (PAM), made the sludge aggregate via charge neutralization. However, the use of PAM alone was not a good choice owing to the low dewatering ability and the loose sludge structure. The results here are helpful for the selection of suitable coagulants for sludge conditioning.