Anaerobic treatment of low, medium and high strength effluent in the agro-industry

Based on the widely applied UASB system for anaerobic wastewater treatment a new generation of more advanced anaerobic reactor systems have recently been developed, according to the so-called expanded sludge bed concept. A successful version of this concept is the Internal Circulation (IC) reactor, characterized by the biogas separation in two stages within a reactor with a high height/diameter ratio and the gas-driven internal effluent circulation. The IC system can handle high upflow liquid and gas velocities, which makes treatment of low strength effluents at short hydraulic retention times, as;well as treatment of high strength effluents at very high volumetric loading rates feasible. During the past years the IC technology has been successfully applied at full scale on a variety of industrial wastewaters; This article describes the design and operational results of three full scale anaerobic treatment plants; with Internal. Circulation reactors treating low, medium and high strength effluents from a dairy industry, food processing plant and brewery respectively. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.