Research On Mass Reduction And Property Improvement Of Sludge In Waterworks

Now the way to discharge waterworks sludge directly into the natrual river is invalid. The quantity and the density of settled solids from coagulation are the critical parameters for waterworks sludge treatment. In our approach, aluminum sulfate, poly-ferric sulfate, PAC, PFS, PAFC, PAFCS, aluminum sulfate+1mg/L PAM and poly-ferric sulfate+1mg/L PAM were used as coagulants in experiments and the parameters of specific resistance to filtration and sedimentation test were measured to estimate the properties of solid settling and dewatering. Zeta potential , floc size and fractal dimension were also measured to discuss the coagulation mechanism.Tested: when the turbidity of raw water is high, PFS can generate the most obvious effect of mass reduction. When the turbidity is low, the use of aluminum sulfate+1mg/L PAM is the best way. In addition, the effects of using PAFC or PAC to treat raw water of high or low turbidity are relatively stable. In the side of settling properties improvement, when PAM is used as a coagulant aid, the turbidity is lower than the turbidity of using inorganic coagulants or polymeric coagulants alone in initial concentration. However, the effect of the removal UV₂₅₄ is poor. At the last stage of concentration, the use of PAM has the obvious effect. When coagulant is used alone, the use of polymer coagulants is better. For dewatering properties improvement, the effect of using polymer coagulant is better than that of using inorganic coagulants, especially PFS and PAFCS. If PAM is used, the effect would be the best.Meanwhile, the author also discussed the mechanism of the improvement of settling properties and dewatering properties according to the measurement of zeta potential , fidc size and fractal dimension. From the measurement of zeta potential, we can conclude that electricity neutralisation will be produced when coagulants are used, but the effects are different. According to the measurement of floc size, the average sludge particle size can reach 1395.78 μm if PAM is used, while the average particle size is only 142.48 μm if aluminum sulfate is used alone. It shows that the properties of settling and dewatering can be improved if PAM is used. Finally, if the fractal dimension is larger, the sludge will have a better flocculation effect and a better...