Purac Aktiebolag

Molnlycke Ab

Sca Development Aktiebolag

Goran E Annergren

Per-Erik Andersson

Hans E Hoglund

Per V Peterson

Thomas G Welander

Inger V Eriksson

Lars E Nasman

Nils L Molin

Bengt G Hansson

Tjell-Ake Hagglund

Lars-Ake T Lindstrom

Lars E Wagberg

Per-Olov Lindblad

Fibres of increased specific surface area, a method for their

The invention relates to a method of treating wastewater from the manufacture of peroxide bleached mechanical or chemi-mechanical pulp. The method comprises a hydrolysis step, a methane fermentation steps and an aerobic step. After the hydrolysis and methane fermentation steps, sludge is separated from the wastewater and partially recycled to the hydrolysis step. The redox potential of the outgoing water from the hydrolysis step is continuously measured and controlled to a value between -400 and -260 mV by regulating the amount of sludge recycled or by passing ingoing wastewater directly to the aerobic treating step.

Method of controlling an anaerobic treatment process

The invention relates to a method of treating wastewater from closed manufacture of mechanical or chemi-mechanical cellulose pulp, which treatment is carried out in a hydrolysis and acid fermentation step and a methane fermentation step with subsequent sludge separation and recycling of separated sludge.

Method for anaerobic wastewater treatment

A method is disclosed for delignification of ligno-cellulose containing fiber material comprising mixing an oxygen-containing gas with the cellulose fiber material so as to atomize the gas and form a foam of the gas and the cellulose fiber material, and without an intervening oxidation step, subjecting the foam to upwardly flowing, substantially non-pressurized, alkali extraction. The alkali extraction step is conducted at a temperature of from about 40.degree. to about 80.degree. C. and at a pH, ligno cellulose containing fiber concentration and oxygen containing gas concentration sufficient to provide a bleached, delignified cellulose fiber without bleaching the lignin substance extracted from the material and to suppress lignin condensation reaction during the extraction.

Method for delignification of ligno-cellulose containing fiber material

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Sundsvall, Sweden

Goran E Annergren