Two‐phase anaerobic treatment system for fat‐containing wastewater

Abstract

Abstract This study was conducted to investigate the feasibility of a two‐phase anaerobic treatment system for fat‐containing wastewater. The two‐phase system was composed of a continuously stirred tank reactor for acidogenesis and an upflow anaerobic sludge blanket (UASB) reactor for methanogenesis. Its performance was compared with a conventional single‐phase system of a UASB reactor treating synthetic wastewater containing major long‐chain fatty acids (LCFAs). LCFAs did not cause any significant problem up to the LCFA mixture loading rate of 1.21 kg LCFA‐COD m −3 day −1 (3500 mg LCFA‐COD dm −3 ) in both systems. However, the efficiency of the single‐phase system deteriorated at loading rates above 1.38 kg LCFA‐COD m −3 day −1 (4000 mg LCFA‐COD dm −3 ), while that of the two‐phase system was still satisfactory. More than 19.2% of LCFAs were degraded and 11.5% of unsaturated LCFAs were saturated in the acidogenesis of the two‐phase system, which led to the enhanced specific methane production rate and the reduced scum layer of the subsequent UASB reactor. Copyright © 2003 Society of Chemical Industry