Unmasking microplastics in anaerobic digestion: Hidden threats, synergistic pollutants, and biodegradation Frontiers — A comprehensive hotspot review

Microplastics (MPs) are emerging as silent disruptors in anaerobic digestion (AD) systems—critical infrastructure in the global push toward sustainable waste-to-energy conversion. While AD has long been championed for its role in renewable energy generation and waste minimization, the infiltration of MPs introduces a complex, largely uncharted set of biochemical and ecological challenges. This review unpacks the novel intersection of MP pollution and AD performance, shedding light on how these persistent particles disrupt microbial pathways, suppress methane yield, and act as vectors for hazardous pollutants like antibiotics, heavy metals, and persistent organic pollutants. Integrating cutting-edge bioremediation strategies and bibliometric insights, this work positions MPs not just as an environmental nuisance but as a biochemical bottleneck in circular economy systems. Understanding and mitigating MP impacts in AD is no longer optional—it's the key to unlocking the next generation of resilient, high-performance bioenergy platforms. • Microplastics (MPs) interfere with anaerobic digestion (AD) and methane production. • MPs act as vectors for heavy metals, antibiotics, and persistent pollutants. • Bioremediation offers sustainable MP degradation in AD systems. • MPs disrupt microbial communities and enzymatic functions in digesters. • Bibliometrics show rising global research interest in MP-AD interaction.