Development of an anaerobic baffled continuous stirring (ABCS) reactor for co-digestion of synthetic high-strength wastewater and solid organic waste

Abstract

To establish high-rate treatment process for co-digestion of high-strength wastewater and solid organic waste, we developed a novel bioreactor system: an anaerobic baffled continuous stirring (ABCS) reactor. This reactor integrates continuous stirring stage with baffled compartments. The first continuously stirred stage promotes solubilization of organic compounds and the second baffled compartment stage contained high concentration of anaerobic sludge. This design enables immediate methanogenesis of solubilized organic matter. In this study, we compared the reactor performance of the ABCS reactor with that of a conventional anaerobic baffled reactor (ABR) during continuous operation for over 100 days, treating identical wastewater derived from a bio-manufacturing process. The ABCS reactor achieved high methane production rates of 2.51 kgCOD m–3 d–1, representing a 1.62-fold increase compared to the ABR. Furthermore, cellulose in the wastewater accumulated in the upstream baffled compartments of ABR, whereas no noticeable accumulation was observed in the ABCS reactor. In addition, the abundance of putative cellulose degraders was much higher in the ABCS reactor than in the ABR, suggesting that these bacteria may contribute to the mineralization of solid organic waste in the baffled compartment. These results demonstrate the successful development of a novel and high-rate treatment system for co-digestion of high-strength wastewater and solid organic waste.