Single-stage anaerobic/aerobic biotreatment of resin acid-containing wastewater

The present study compares the coupled anaerobic/aerobic integrated system (CANOXIS) operated at different aeration and liquid recycle rates to the conventional upflow anaerobic sludge bed (UASB) system for the laboratory scale treatment of a resin acid-containing effluent. Dehydroabietic and abietic acids were added in equal proportions to a sucrose-based feed stock. Even under oxygenation conditions, methane was formed, indicating that the aerobic and facultative microorganisms consumed oxygen fast enough to maintain a reduced microenvironment essential to the methanogens. Eight weeks of resin acid loading at 100 mg/L exerted no significant effects on the high efficiency and stable performance of UASB reactors. The CANOXIS systems showed with time a reduced discharge of residual resin acids in the effluent and a decrease of the amount of resin acids adsorbed onto the biomass when compared to the UASB reactor. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.