Other

Kemira Oyj

Miia Niemelä

Mehrdad Hesampour

Sakari Halttunen

Jonni Ahlgren

Kaisa Karisalmi

Eija Korte

Jussi Ruotsalainen

Eija Saari

Heli Virkki

Maria Luhtala

The invention relates to a method for treating wastewater in an activated sludge process, which comprises a biological treatment step followed by a sedimentation step for separation of sludge and treated effluent water. The method comprises directing a part of the treated effluent water as a backflow from the sedimentation step to the biological treatment step, the backflow having an original pH value; adjusting the backflow pH from the original pH value to a first pH value between the sedimentation step and the biological treatment step, and adding a coagulant and/or an oxidant to the backflow after the adjustment of the backflow pH to the first pH value and before backflow's entry to the biological treatment step.

Method for treating wastewater

A method for removing humic substances comprising lignin, other lignin type compounds and their disintegration products from an aqueous alkaline waste water from a bleaching of chemical pulp, which method comprises &#x2014;obtaining an aqueous alkaline waste water comprising humic substances such as dissolved lignin, and &#x2014;adding a high cationic starch having a charge density value of at least 1.8 meq/g dry matter of starch derivates determined at pH 7-7.5 to the alkaline waste water to precipitate humic substances.

Method for removing humic substances from an aqueous alkaline solution

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Helsinki, Finland

Miia Niemelä