Biogas Recovery from Palm Oil Mill Effluent in Malaysia: A Review of Technology Transition, Deployment Readiness, and Sustainability Challenges

Palm oil mill effluent (POME), the primary liquid residue from crude palm oil (CPO) extraction, has shifted from industrial wastewater to a valuable feedstock for renewable energy and resource recovery. This review synthesizes recent developments in sustainable POME management in Malaysia through a narrative review of peer-reviewed literature (Scopus, Web of Science, Google Scholar; 2013 onwards) and institutional reports, across four dimensions: anaerobic digestion technologies, environmental performance, techno-economic viability, and policy drivers. Characterized by a high organic load (COD 15,000–100,000 mg L−1; BOD 10,250–43,750 mg L−1), POME yields roughly 28–34 m3 of biogas per m3 of effluent with a 54–65% methane content, while its digestate offers nutrient recovery potential to replace synthetic fertilizers. Covered lagoons and continuous stirred-tank reactors (CSTRs) show the highest deployment potential, whereas upflow anaerobic sludge blanket (UASB) systems and anaerobic membrane bioreactors (AnMBRs) remain technically and economically constrained. Capital intensity, infrastructure gaps, and operational demands limit wider adoption. At the same time, digital process control and regulatory drivers such as the Malaysian Sustainable Palm Oil (MSPO) certification and the European Union Deforestation Regulation (EUDR) are critical enablers. Re-envisioning POME management as an integrated resource-recovery platform can lower greenhouse gas emissions, close nutrient loops, and accelerate Malaysia’s circular bioeconomy.