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 co nventional upflow anaerobic sludge bed (UASB) system for the laboratory sca le treatment of a resin acid-containing effluent. Dehydroabietic and abieti c acids were added in equal proportions to a sucrose-based feed stock. Even under oxygenation conditions, methane was formed, indicating that the aero bic and facultative microorganisms consumed oxygen fast enough to maintain a reduced microenvironment essential to the methanogens. Eight weeks of res in acid loading at 100 mg/L exerted no significant effects on the high effi ciency 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 compa red to the UASB reactor. (C) 1998 Published by Elsevier Science Ltd. All ri ghts reserved.