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.