When flocculating an aqueous suspension of suspended solids using a high molecular weight synthetic polymeric flocculant the shear stability of the flocs is increased if the polymeric material includes polymeric particles of below 10 .mu.m dry size. The flocculated solids can therefore be subjected to shear without increasing the amount of discrete suspended solids in the aqueous medium and generally they are suspended to shear by shearing the aqueous medium containing them, either before dewatering, generally on a centrifuge, piston press or belt press, or by continuously agitating them, for instance in a chemical reaction medium. The polymeric material is generally formed by mixing into water polymeric particles made by reverse phase or emulsion polymerization in the presence of added cross linking agent. Alternatively particles insolubilized by insoluble monomer may be used. A reverse phase dispersion of water soluble polymer may be used if the particles remain undissolved, e.g. if they are added in the absence of an oil in water emulsifying agent.
This application is a continuation of U.S. application Ser. No. 07/145,622 filed on Jan. 19, 1988 now abandoned which was a continuation-in-part of U.S. application Ser. No. 855,509 filed by us Aug. 23, 1986 now U.S. Pat. No. 4,720,346.
Priority Data
Aug 25, 1986 [GB] 8510496 Oct 29, 1986 [GB] 8526624
Water-soluble, branched, high molecular weight, cationic and non-ionic polymeric flocculants capable of manifesting their full performance potential without shearing are produced by polymerizing ethylenically unsaturated cationic and non-ionic monomers and a branching agent in the presence of a chain-transfer agent. They are useful as flocculating agents for releasing water from dispersions of suspended solids.
A water-soluble, cationic polymer comprising from about 1 to about 65 mole percent of one or more cationic monomers, from about 99 to about 35 mole percent of one or more nonionic monomers and from about 1 to about 1000 ppm, based on the total monomer content, of one or more hyperbranched monomers wherein the hyperbranched monomer contains from about 2 to about 20 allyl, vinyl, or acrylic end groups and method of dewatering sludge is disclosed.
Water-soluble, high molecular weight, polymeric, microparticles with a high degree of branching are disclosed. A microemulsion polymerization process for preparing the microparticles is also disclosed. The microparticles give excellent results in a number of solid-liquid separation processes.
