Abstract: The present invention relates to a process for deinking recycled fibers wherein an aqueous pulp suspension with recycled fibers, printing ink and calcium carbonate is provided. The hardness of the suspension is stabilized by causing dissolution of calcium carbonate contained in the suspension or in an aqueous fluid added to the suspension. The increased hardness suspension is subjected to flotation to separate said printing ink from the suspension. The present invention also relates to use of a weak acid for dissolving calcium carbonate and for stabilizing the hardness in a flotation process for the deinking of an aqueous pulp suspension containing said recycled fibers, printing ink and calcium carbonate.

Abstract: The present invention relates to an apparatus and a method for controlling the alkalinity and the pH of an industrial process. The apparatus is adapted for being located outside a main process stream of the industrial process. The apparatus includes inlet means (2, 3, 4) for a basic substance, an acidic substance and water, control means (6) for said inlet means (2, 3, 4), a reactor (1) for reacting the basic substance, the acidic substance and the water for providing a predefined alkalinity and pH in the resulting aqueous buffering mixture, and outlet means (9) for supplying said buffering mixture to the main process stream for controlling the alkalinity and the pH of the industrial process.

Abstract: The present invention relates to an apparatus and a method for controlling the alkalinity and the pH of an industrial process. The apparatus is adapted for being located outside a main process stream of the industrial process. The apparatus includes inlet means (2, 3, 4) for a basic substance, an acidic substance and water, control means (6) for said inlet means (2, 3, 4), a reactor (1) for reacting the basic substance, the acidic substance and the water for providing a predefined alkalinity and pH in the resulting aqueous buffering mixture, and outlet means (9) for supplying said buffering mixture to the main process stream for controlling the alkalinity and the pH of the industrial process.

Abstract: The invention relates to a process for controlling microbial growth in a production line for cellulosic products with the aid of gases. The invention also relates to the use of gases such as carbon dioxide, nitrogen, argon and/or non-naturally occurring mixtures thereof for controlling microbial growth. In the process an aqueous material containing water and suspended pulp fibers and/or additives therefor is treated with the gaseous inhibitor to significantly retard or inhibit the growth of microorganisms therein. An oxygen rich gas may be introduced in addition to the inhibitor of the invention.