The use of aerobic selectors in activated sludge systems for treatment of wastewater from the pulp and paper industry

Lab-scale have been made with an aerobic selector followed by an aerated reactor. Sulphate mill effluent and waste paper mill effluent were used during the tests. It was verified that the treatment system could produce a sludge with an SVI below 140 ml/g and a high COD-reduction. It was also found that a high fraction of the COD was reduced as uptake and storage in the selector. The COD was thereafter oxidized in the aerated reactor. Full scale plants have been studied where aerobic selectors are used. The plants produce a sludge with a stable SVI below 150 ml/g. This enables a stable function regarding COD-reduction at varying loading conditions and at frequent product quality changes.