In this study, cationic polyacrylamide (CPAM) modified diatomite and cetyl trimethyl ammonium bromide (CTAB) modified diatomite were synthesized and used as conditioner in sewage sludge dewatering. The effects of these two types of modified diatomite on the dewaterability and settling performance of activated sludge were studied. The mechanism of the two types of modified diatomite in the activated sludge system was elucidated. The efficiency of CPAM-modified diatomite was better than that of CTAB-modified diatomite in improving the settleability and dewaterability performance of sludge. The results indicated that specific resistance to filtration (SRF) was decreased from 8.52×1012m/Kg to 0.92×1012 m/Kg, and the water content in the remaining sludge cake after pumping filtration was decreased from 92.2% to 68.1%. by adding 0.4% of CPAM-modified diatomite and pH=3.5, which result in optimal sludge settling of activated sludge. Further studies showed that the polymer/surfactant adsorbed in diatomite increased sludge dewaterability and improved the sedimentation rate as a result of stripping extracellular polymer substances (EPS) and damaging the internal structure of sludge conduce bound water releasing. According to scanning electron microscope(SEM) images, two types of modified diatomite powder not only kept the porous, but also shown more complete and uniform structure in comparison to nature diatomite.

No abstract