Enhancement of bioenergy production and effluent quality by integrating optimized acidification with submerged anaerobic membrane bioreactor

To ensure effluent quality in the treatment of high-strength organic waste and enhance CH₄ production, this study investigates the applicability of process optimization and a submerged anaerobic membrane bioreactor (SAMBR) for a two-phase anaerobic digestion (TPAD) system. The use of response surface methodology (RSM) suggests that the optimum conditions for maximum volatile fatty acids (VFA) production were a hydraulic retention time (HRT) of 2.01 days and a substrate concentration of 29.30 g/L based on chemical oxygen demands (COD). A confirmation experiment showed that an empirical model could predict a VFA increase of 76% under the proposed conditions with a relative error of 4%. SAMBRs could convert the VFA in acidogenic effluent to CH₄ with an average production rate of 0.28 m³/m³/d in an HRT of 14 days. All of the SAMBRs could achieve COD removal rates of over 99% by the increased solid retention time and secondary membrane formation.