Overcoming micro/nanoplastics-induced inhibition in anaerobic digestion: Advances in remediation techniques

Anaerobic digestion (AD) is a proven and enduring technology widely employed for sustainable waste management and renewable energy recovery. However, growing evidence indicates that micro/nanoplastics (MPs/NPs), increasingly released into waste and wastewater streams, can disrupt the stability and efficacy of the AD process. While several promising remediation strategies have been proposed in previous studies, thorough mechanistic evaluations of these techniques remain limited. This review comprehensively discusses how MPs/NPs affect AD performance, including reductions in biogas yield, organic degradation efficiency and effluent quality. Key inhibition mechanisms, such as physical damage to microbial cells, enzyme suppression, and the propagation of antibiotic resistance genes, are covered. Importantly, for the first time, the review provides a detailed overview of the emerging remediation strategies that mitigate the impacts of MPs/NPs on AD. Strategies such as thermal hydrolysis, ultrasonication, alkaline conditioning, ozonation, Fenton oxidation, and carbon-based additives are comparatively evaluated. Special attention is paid to how these strategies counteract MPs/NPs-induced stress, restore microbial activity, and enhance AD system resilience. Their practical applicability, advantages, limitations and environmental implications are also addressed. Looking forward, this review spotlights the future research directions needed to enhance the resiliency of the AD process treating MPs/NPs-laden waste streams. This review can serve as a foundational reference for researchers and practitioners seeking to develop efficient strategies to overcome MPs/NPs-caused detrimental impacts on AD process. • Impacts of micro/nanoplastics on anaerobic digestion are comprehensively reviewed. • MPs/NPs reduce biogas yield, organic degradation, and effluent quality in AD systems. • Inhibition mechanisms include toxic additives, enzyme loss, ROS stress, and cell damage. • Pretreatment and in-situ strategies to mitigate MPs/NPs in AD are comprehensively reviewed. • Key challenges, research gaps, and future directions are critically discussed.