Uddeholms Aktiebolag

Bengt Gunnar Broddevall

Lars-Gustaf Anderson

Hilding Roland Andersson

Erik Axel Lindberg

A process for purifying the effluent from a pulp bleaching process which includes a chlorine treatment, an alkali extraction, and a final bleaching is disclosed, wherein a number of washing steps are connected in counter-current series from a final wash step in the final bleach section to the wash step of the first alkali extraction stage, the strongly polluted effluent from the wash step of the first alkali extraction stage is passed through a first column containing a bed of particulate porous resin which traps and retains organic pollutants in the effluent, and a combined effluent which includes an acidic polluted liquor from the chlorine bleaching stage and a partly purified filtrate from the first column is fed through a second column which contains a bed of particulate porous resin which traps organic pollutants fed therethrough, with the resin bed in the second column being activated by the acidic nature of the combined effluent, with chloride ions in the combined effluent essentially passing through the resin bed without being trapped by the resin, so that the chloride ions are discharged with the purified filtrate from the second column. The purified filtrate is the final wash liquor effluent of the system of counter-current washing steps. By this process the organic pollutants are efficiently separated from the wash liquors, with the chemical purification cost kept at a low level. The separated pollutants are obtained in a relatively concentrated form which facilitates evaporation and burning. The main portion of the chloride ions arising from the chlorination stage are removed with the final wash liquor effluent, which is an important advantage for further processing.

Process related to pulp bleaching effluent purification using ion

A process for decoloring an aqueous effluent from the bleaching of sulphate pulp with chlorine or chlorine containing compounds, said effluent containing dark colored lignin degradation products, said bleaching including at least one alkali extraction stage, comprises A. treating the aqueous effluent from at least one alkali extraction stage in the bleaching with at least one acid selected from the group consisting of sulphuric acid, sulphurous acid and hydrochloric acid until a precipitate forms, said precipitate consisting essentially of dark colored lignin degradation products and other organic material B. separating the treated aqueous effluent from the precipitate and C. contacting the treated aqueous effluent which has been separated from the precipitate with a phenolic resin which is activated by the acidic effluent, said activated resin binding the dark colored lignin degradation products and separating a decolored effluent from the loaded resin.

Purification of waste water from sulphate pulp bleaching plants

A method of bringing at least two liquids of different pH values into contact with a synthetic resin and substantially eliminating volume changes in the resin bed due to changes in the pH of the liquid phase, is provided wherein the resin is made up of a mixture of at least two different resins, the volumes of which depend on the pH of the liquid phase in which the resin is located, a first resin being one having its maximum volume when located in an acid environment and its minimum volume when located in an alkaline environment, a second resin being one having its minimum volume when located in an acid environment and its maximum volume when located in an alkaline environment, the ratio of the two resins in the mixture being such that volume changes in each resin resulting from changes in the pH of their environment substantially compensate one another so that the resin mixture maintains a substantially uniform volume in acid and alkaline environments.

Growing community of inventors

Skoghall, Sweden

Bengt Gunnar Broddevall