Kemira Oyj

Joonas Likander

Rosa Carceller

Matti Hietaniemi

Asko Karppi

Jyri Välimäki

Jyri Valimaki

Sakari Halttunen

Fazlollah Azarnoush

Petteri Suominen

Outi Gronfors

Outi Grönfors

Bengt Hansen

Outi GRÖNFORS

Roger Bårström

Roger Barstrom

A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

Method for treating aqueous feed by dissolved gas flotation

A method for dewatering of biological sludge is disclosed. The method includes addition of a flocculant to a biological sludge, which includes an aqueous phase and a suspended solid organic material, flocculating and dewatering the sludge. The flocculant includes a polymer composition, which includes a cationic crosslinked first polymer, which is selected from crosslinked polyamines, and a cationic second polymer, which is a polymer obtained by polymerization of (meth)acrylamide and cationic monomers, the second cationic polymer being polymerized in presence of the cationic first polymer.

Method for dewatering of biological sludge using a polymeric flocculant

A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

Method for dewatering of sludge from a pulp, paper or board making process

A polymer composition includes a first host polymer, which is a copolymer of (meth)acrylamide and at least one cationic first monomer, and a second polymer, which is a copolymer of (meth)acrylamide and at least one cationic second monomer. The second polymer is polymerised in presence of the first host polymer, and the first host polymer has a higher cationicity than the second polymer, the difference in cationicity of the first host polymer and the second polymer being at least 3 mol-%, at least 5 mol-%, more preferably at least 7 mol-%. The polymer composition has a standard viscosity of &#x3e;2.0 mPas, measured at 0.1 weight-% solids content in an aqueous NaCl solution (1 M), at 25&#xb0; C., using Brookfield VII T viscometer with UL adapter. The invention relates also to uses of said polymer composition.

Polymer composition and its uses

The present invention relates to a process for treating primary sludge in a wastewater treatment plant, comprising the steps of admixing an organic coagulant and/or polymer to wastewater; allowing a primary treatment of the wastewater in the presence of the organic coagulant or polymer; separating solids as a primary sludge from said primary treatment; and dewatering the primary sludge. The present invention further relates to a method of improving primary sludge dewaterability and improving energy balance of a wastewater treatment plant.

Improving sludge dewaterability and energy balance of wastewater treatment

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Espoo, Finland

Joonas Likander