Integration of acidogenic and methanogenic processes for simultaneous production of biohydrogen and methane from wastewater treatment

Abstract

Feasibility of integrating acidogenic and methanogenic processes for simultaneous production of biohydrogen (H 2) and methane (CH 4) was studied in two separate biofilm reactors from wastewater treatment. Acidogenic bioreactor (acidogenic sequencing batch biofilm reactor, AcSBBR) was operated with designed synthetic wastewater [organic loading rate (OLR) 4.75 kg COD/m 3-day] under acidophilic conditions (pH 6.0) using selectively enriched acidogenic mixed consortia. The resultant outlet from AcSBBR composed of fermentative soluble intermediates (with residual carbon source), was used as feed for subsequent methanogenic bioreactor (methanogenic/anaerobic sequencing batch biofilm reactor, AnSBBR, pH 7.0) to generate additional biogas (CH 4) utilizing residual organic composition employing anaerobic mixed consortia. During the stabilized phase of operation (after 60 days) AcSBBR showed H 2 production of 16.91 mmol/day in association with COD removal efficiency of 36.56% (SDR A—1.736 kg COD/m 3-day). AnSBBR showed additional COD removal efficiency of 54.44% (SDR M—1.071 kg COD/m 3-day) along with CH 4 generation. Integration of the acidogenic and methanogenic processes enhanced substrate degradation efficiency (SDR T—4.01 kg COD/m 3-day) along with generation of both H 2 and CH 4 indicating sustainability of the process.