Ciba Specialty Chemicals Water Treatments Limited

Steven Weir

Jonathan Robert Hughes

Malcolm Skinner

Michael Green

Tony Whittaker

Janine Marie Griffith

Simon Paul Oldfield

Paul Moran

Mark John Stringer

John Stephen Robinson

A method of dewatering a suspension of solids in an aqueous medium, comprising introducing into the suspension a flocculating system, which flocculation system comprises, a) a substantially non-ionic water-soluble polymer and b) a cationic polymeric flocculant of intrinsic viscosity at least 4 dl/g, thereby causing the solids to flocculate, separating the flocculated from aqueous medium, characterized in that i) the components a) and b) are introduced into the suspension as an aqueous blend; or ii) component a) is a non-ionic polymer that has an average molecular weight of below 750,000 and components a) and b) are introduced into the suspension as an aqueous blend or separately. Also claimed is an aqueous composition comprising the substantially non-ionic water-soluble polymer and cationic polymer, method for making it and a composition comprising a blend of substantially anhydrous particles of component (a) and component (b). The method and novel composition are particularly suitable for dewatering aqueous suspensions such as sewage sludges.

Treatment of suspensions

A process of flocculating and dewatering an aqueous suspension of suspended solids comprising, introducing into the suspension, (a) substantially linear polymer, (b) structured polymer, characterised in that the polymers are introduced into the substrate sequentially. The process brings about improvements in filtration.

Process for flocculating suspensions

A method of dewatering an aqueous mineral suspension comprising introducing into the suspension a flocculating system comprising, a) a substantially non-ionic polymeric flocculant and b) an anionic polymeric flocculant, characterised in that, the substantially non-ionic polymeric flocculant is added to the suspension before the addition of the anionic polymeric flocculant. The method is useful for flocculating China clay suspensions, suspensions of s welling clays, calcium carbonate suspensions, titanium dioxide suspensions, suspensions of coal tailings, red mud and phosphate slimes etc.

Flocculation of mineral suspensions

A process of flocculating microbial cell material from a suspending medium which contains cell material, comprising adding to the suspending medium a first polymeric material which is cationic and has intrinsic viscosity of not more than 2 dl/g, and subsequently or simultaneously adding to the suspending medium a second polymeric material which is cationic or substantially non-ionic and has intrinsic viscosity of at least 4 dl/g, and allowing the cell material to flocculate.

Flocculation of cell material

A process of flocculating and dewatering an aqueous suspension of suspended solids comprising, introducing into the suspension, (a) a concentrated polymer solution and, (b) a dilute polymer solution, characterised in that the concentrated and dilute polymer solutions are introduced into the substrate substantially simultaneously. Preferably the concentrated and dilute polymer solutions are introduced into the suspension as an aqueous composition comprising a dilute aqueous solution of polymer and a concentrated solution of polymer. The process brings about improvements in filtration and cake solids.

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Huddersfield, United Kingdom

Steven Weir