Abstract: 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 t

Abstract: 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, comprisesA. 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 materialB. separating the treated aqueous effluent from the precipitate andC. 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.

Abstract: 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.