Energy Recovery From Conventional Biogas Digester Effluent with a Novel Bioreactor Configuration

Abstract

Anaerobic biotechnology offers both economic and ecological benefits for sustainable renewable energy production and sustainable agriculture practice. In this study, a novel bioreactor configuration, which is a combination of a continuous flow stirred-tank reactor (CSTR) and an up flow sludge blanket reactor (UASB), was used in order to valorize the residual organic content in the effluent of a conventional CSTR reactor. Thereby, maximum utilization of total COD potential was aimed by further processing of the residual COD from conventional farm based CSTR type digester effluent. The effluent of the CSTR reactor (dry matter 10%, HRT: 30 days) was fed into UASB reactors under varying HRT and Organic Loading Rate (OLR) conditions. Up to 98% COD removal was achieved in 4 L UASB reactor corresponding to maximum biogas production of 0.7 m3 biogas/kg CODremoved in UASB reactor. To the best of our knowledge, this integrated system is used for the first time to maximize the COD conversion into bio-methane during biogas production from laying hen litters. Thereby, a novel approach was presented a promising solution for the maximum valorization of animal manure as an alternative to conventional farm based biogas digester systems.