Ciba Specialty Chemicals Water Treatments Limited

Peter Norman

Tony Whittaker

Darryl Smith

Nils Berggren

Helen Elizabeth Read

A process of dewatering an aqueous suspension comprising treating the suspension with a dewatering amount of a reverse phase polymer, and subjecting the suspension to a mechanical dewatering to form a cake, characterized in that the reverse phase polymer only partially inverts to bring about flocculation and thickening of the suspension, and then fully inverts during the further dewatering to form a cake.

Dewatering process

A process of dewatering an aqueous suspension comprising dosing the suspension with a flocculating amount of a first flocculant to form a thickened suspension and mixing into the thickened suspension a dewatering amount of a second flocculant and subjecting the thickened suspension to mechanical dewatering to form a cake, characterised in that the second flocculant comprises a water-soluble or water swellable polymer that is mixed into the suspension in the form of (i) substantially dry polymer particles or (ii) an aqueous composition comprising dissolved or hydrated polymer having a polymer concentration of at least 2% by weight and having a intrinsic viscosity of at least 3 dl/g.

A process of dewatering aqueous suspension employing a flocculating system comprising treating the suspension with a flocculating amount of a first flocculant and a dewatering amount of a second flocculant, and subjecting the suspension to mechanical dewatering to form a cake, wherein the first flocculant brings about flocculation and assists thickening of the suspension and the second flocculant is a water-soluble or water swellable polymer that is mixed into the suspension is a water-soluble or water swellable particulate polymer having a particle diameter of at least 20 microns.

A process of dewatering an aqueous suspension comprising treating the suspension with a dewatering amount of a reverse phase polymer, and subjecting the suspension to a mechanical dewatering to form a cake, characterised in that the reverse phase polymer only partially inverts to bring about flocculation and thickening of the suspension, and then fully inverts during the further dewatering to form a cake.

Process for the dewatering of aqueous suspensions

A process of dewatering an aqueous suspension employing a flocculating system comprising treating the suspension with a flocculating amount of a first flocculant and a dewatering amount of a second flocculant, and subjecting the suspension to mechanical dewatering to form a cake, wherein the first flocculant brings about flocculation and assists thickening of the suspension and the second flocculant further dewaters the suspension, characterized in that the second flocculant is a water-soluble or water swellable polymer that is mixed into the suspension in the form of aqueous composition comprising dissolved or hydrated polymer having a Brookfield viscosity of above 30,000 cps (measured at 20&#xb0; C.).

Compositions comprising of blends of polymeric materials, including a cationic polymer having an intrinsic viscosity of from 8 to 17 dl/g and a cationic content of from 20 to 100% which may be used in the dewatering of thermophilic sludges.

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Liversedge, United Kingdom

Peter Norman