Optimization of Operational Parameters for Enhanced Biogas Production in Pressurized Anaerobic Baffled Reactor (PABR) Treating Domestic Wastewater

In the pursuit of sustainable and energy-positive wastewater treatment technologies, anaerobic digestion (AD) processes have garnered significant attention due to their dual role in organic waste stabilization and renewable energy recovery in the form of biogas. The Pressurized Anaerobic Baffled Reactor (PABR), a novel advancement in the family of high-rate anaerobic bioreactors, presents a promising platform for efficient wastewater treatment coupled with enhanced methane yield. This study delves into the optimization of critical operational parameters in PABR systems—namely hydraulic retention time (HRT), organic loading rate (OLR), reactor pressure, temperature regimes, influent pH, and compartmental flow dynamics—to maximize biogas production while maintaining robust treatment efficacy for domestic wastewater. Unlike conventional anaerobic baffled reactors, PABRs operate under pressurized conditions that inherently influence microbial kinetics, mass transfer rates, and solubility of metabolic gases such as methane and carbon dioxide. The study also explores the synergistic effects of microbial syntrophy, pressure-induced methanogen activity, sludge bed granulation, and compartmental stratification in promoting resilient and high-rate anaerobic digestion. Experimental analyses are supported by kinetic modeling using modified Gompertz and first-order models, alongside sensitivity analysis for determining parameter influence on gas yield. The findings highlight that an optimal pressure range of 2.5 to 3.0 bar, an HRT of 18-20 hours, and an OLR of 3–5 kg COD/m³/day yielded the highest biogas productivity with stable COD removal efficiency exceeding 85%. The implications of these results extend toward decentralized wastewater treatment in urban and peri-urban settings, providing a model for low-energy, high-yield, and climate-aligned bioprocess design. Recommendations for future research and large-scale integration of PABRs into municipal wastewater infrastructures are also discussed.