There were a large number of sludge with much water and many negatively charged particle group during treating municipal sewage. The sludge should be dehydrated for reducing moisture content and volume of sewage sludge. Flocculant was utilized for improving the dewatering performance of sludge for better effects. The copolymer P(AM-DMDAAC) (PDA for short) of acrylamide(AM for short) and dimethyl diallyl ammonium chloride(DMDAAC for short) was concerned widely. Unfortunately, there is a great disparity betwe...