Optimization and simulation-based comparative performance analysis of Palm Oil Mill Effluent (POME) treatment in Continuous Stirred Tank Reactor (CSTR) and covered lagoon system: Insights from industrial applications

This study presents the first simulation-based comparison of CSTR and covered lagoon for biogas production from palm oil mill effluent (POME) using anaerobic digestion (AD), integrating simulation, optimization, and economic evaluation. Simulations using SuperPro Designer software were validated against two years of industrial plant data, including chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS), and biogas composition. Results show that CSTR generates 44% more biogas than covered lagoon with the same POME feed. Optimization identified optimal CSTR operating conditions at 76% recirculation and an organic loading rate (OLR) of 4.3 kg/m 3 ·day, yielding 23,684 m 3 /day of biogas with a methane yield of 0.33 m 3 CH 4 /kgCOD removed . Economic analysis showed a net present value (NPV) of $16.75 million and a 4.02-year payback, confirming technical and financial viability. The CSTR outperforms the covered lagoon with a 30.95% higher methane yield, 3.2% greater COD removal, 21.6% lower equipment volume, and a 25.5% smaller footprint, improving space utilization and process efficiency. These findings provide actionable insights into system trade-offs and serve as a guide for palm oil mills in selecting suitable technologies for biogas production. While covered lagoons remain a lower-cost option for capital-constrained mills, CSTRs offer better long-term performance and sustainability. Future research should focus on integrating advanced effluent polishing processes to replace conventional multi-pond treatment systems to further enhance environmental sustainability. • First simulation-based comparison of CSTR and covered lagoon for POME. • CSTR produce 44.4% more biogas and 30.95% higher methane yield. • CSTR have a higher NPV ($16.75M) and shorter payback (4.02 years).