Study On Development Of An Environment-friendly Composite Flocculant And Its Application In Excess Sludge Volume Reduction

According to the current status and problems in excess sludge treatment and disposal, the study aimed at improving the efficient of excess sludge dewatering by using of a new type of environment-friendly composite flocculant to reduce the excess sludge volume, and also provided the basis for resource utilization of excess sludge.Through a series of experiments, the results showed that the optimal formula of the composite flocculant was as follow:PAC 0.53g/L, PFS 2.47g/L, natural organic polymeric flocculant B 0.05g/L, natural inorganic minerals A 0.45g/L, coagulant aid C 1.17g/L. The grain size was also determined as follow: PAC 40mesh, PFS 60mesh, natural organic polymeric flocculant B 80mesh, natural inorganic minerals A 100mesh. Stirring time and stirring speed were measured to examine change of sludge dewatering performance in this study. The experiments results showed that the optimal conditions were the stirring speeds of 300r/min and 100r/min and the stirring time of 2min and 6min in rapid and slow stirring stage respectively, and the water content of sludge cake was 72.01%. The re-dissolution of Nitrogen and Phosphorus from sludge cakes, treated by the type of environment-friendly composite flocculant, was also invesgated, which showed good immobilization efficient to Nitrogen and Phosphorus in the sludge. The application of the environment-friendly composite flocculation could obviously reduce their re-dissolution to make the excess sludge better Utilization.