Pretreatment of Wastewater from Licorice Processing-A Preliminary Evaluation

This study was performed as a preliminary investigation of anaerobic digestion and the activated sludge process as pretreatment options for highly loaded wastewater from licorice processing (approximately 8000 mg COD/L). Only 15% reduction of initial chemical oxygen demand (COD) was achieved by anaerobic digestion, whereas up to 80% reduction was attained with activated sludge process. Adsorption using powdered activated carbon (PAC) was studied for the removal of color and residual organics from the effluent of aerobic treatment. The combination of aerobic biological treatment with activated carbon adsorption offers a high-quality effluent, however only at very high carbon dosage (>2 kg PAC/m(3)).