Aerobic Composting of Municipal Solid Waste: A Superior Carbon Capture, Utilisation and Storage (CCUS) Pathway Compared to Anaerobic Digestion

Abstract

Rapid urbanisation and the concomitant surge in municipal solid waste (MSW) generation are intensifying environmental and public health risks globally, notably through greenhouse gas (GHG) emissions and the loss of recoverable nutrients. Framed within an urban carbon–nutrient cycle perspective, this review critically positions aerobic composting as a scalable, low-risk carbon capture, utilisation, and storage (CCUS) pathway for MSW management, in contrast to forced methanogenesis via anaerobic digestion (AD). Synthesised evidence demonstrates that optimised aerobic composting systems effectively suppress methane emissions while facilitating the transformation and stabilisation of organic carbon into humified soil organic matter, thereby enabling durable carbon sequestration. Concurrently, compost application improves soil physicochemical properties, enhances water-holding capacity, and supports sustained crop productivity, linking waste management with climate-resilient agroecosystem functioning. Although AD enables bioenergy recovery, its net climate benefits remain conditional upon stringent control of fugitive methane emissions, efficient digestate management, and sustained operational stability—factors that often introduce uncertainty under field-scale conditions. In contrast, aerobic composting offers a more direct and comparatively lower-risk methane mitigation pathway, alongside distinct advantages for carbon market integration, including greater transparency in monitoring, reporting, and verification (MRV), and clearer demonstration of additionality and permanence. Its relatively low technological and infrastructural requirements further enable decentralised deployment, particularly in resource-constrained settings. Notably, emerging innovations such as Novcom technology underscore the transformative potential of advanced composting systems by enabling rapid MSW bioconversion (≈21 days), effective pathogen inactivation, and substantial reduction in heavy metal bioavailability (up to 80%) via organo-complexation. Critically, such systems achieve near-complete methane mitigation (up to 99%), reinforcing their climate mitigation efficacy without necessitating extensive infrastructure. Collectively, aerobic composting represents a robust and integrative solution for sustainable MSW management, delivering synergistic environmental, agronomic, and socio-economic co-benefits. This review advocates for its prioritisation within municipal policy frameworks and operational strategies, alongside targeted research on feedstock optimisation, process intensification, and long-term soil carbon dynamics to fully realise its CCUS potential.