Study on Properties of Waterworks Sludge and Effect of Coagulants Conditioning on Dewatering Performance

In order to study the influence of coagulants conditioning on dewatering performance of waterworks sludge,and according to different water quality characteristics( high turbidity and high organic matter concentration),characteristics research and conditioning experiments of sludge from two typical waterworks were performed. The results indicated that there were significant differences between the two waterworks sludge in types and contents of organic matter and Zeta potential. The sludge from waterworks in Shenzhen had relatively high COD content and contained protein,which restricted the dewatering property. Under the condition of natural sedimentation,the sludge from Shanghai waterworks performed better than that from Shenzhen waterworks. The significant difference between the two types of sludge in specific resistance to filtration( SRF) and capillary suction time( CST) could also explain that dewatering performance of the sludge form Shenzhen waterworks was poorer than that form Shanghai waterworks. Comparison of coagulants conditioning data between the two types of sludge showed that higher concentration of dissolved organic matter in the sludge form Shenzhen waterworks directly affected the hydrolysis process and reduced coagulation effect when coagulants were added. For the sludge from Shanghai waterworks,the effect of PAM on improvement of the dewatering performance was the weakest,and PAM could increase the TOC easily. However,PAC and HPAC showed the ideal coagulation effect,and HPAC had more obvious advantage due to its stronger charge neutralization capacity. Zeta potential of the sludge form Shenzhen waterworks was higher,anionic PAM could neutralize the positive charge on the surface of sludge particles,and its strong adsorption-bridging ability could also effectively concentrate and settle sludge particles,showing the optimal sludge conditioning effect.