Patent ID: 8088288

Claim:
A process of dewatering an aqueous suspension of sewage sludge comprising the following steps: a) treating the suspension with a dewatering amount of a reverse phase polymer which is a dispersion of polymer particles in oil, wherein the polymer is cationic and formed from at least 30% by weight of cationic monomer or monomers, and has an intrinsic viscosity of greater than 0.5 dl/g, wherein the reverse phase polymer only partially inverts releasing sufficient polymer to bring about flocculation and thickening of the suspension, involving the release of free water to produce a thickened suspension, wherein the amount of the reverse phase polymer partially released in this step is between 10 and 70% by the weight of polymer contained in the emulsion, and wherein the release of free water is achieved by free drainage or filtration; b) the remainder of the polymer is released from the reverse phase polymer as the reverse phase polymer fully inverts in the thickened suspension; c) the polymer released in step b) is mixed using mixing equipment into and distributed throughout the thickened suspension; and d) the thickened suspension is subjected to mechanical compression dewatering to form a cake.