Carbon Sequestration and Recycling from Wastes: A Sustainable Approach

This chapter addresses the issue of implementing a sustainable approach to climate change mitigation through carbon sequestration and waste recycling and turning waste streams into carbon sinks and valuable resources within a circular economy framework. Rising world emissions, especially in terms of landfills and organic wastes representing 3–5% of GHGs, are highlighting the urgency with technologies such as biochar production, bioenergy with carbon capture and storage (BECCS), mineral carbonation of construction wastes, and carbon capture and utilization from industrial residues with a net negative emission potential of 10–15 Gt CO2/year in 2050. Key approaches are pyrolysis toward biochar soil amendment (0.7–1.8 Gt CO2-Ceq/year sequester capacity, with soil fertility improvement), BECCS (bio-gas-CCS pathways for energy recovery), accelerated carbonation of recycled concrete aggregates (10–50 kg CO2/ton sequestration), and post-combustion capture valorization pathways on steel slag and fly ash toward the production of durable carbonates. Life-cycle assessments show composting and anaerobic digestion leading to a diversion of organics from landfilling, resulting in 41–500 kg CO2e/ton, compared to the 400 kg CO2e/ton from landfilling. Techno-economic analyses provide considerable proof of costs in the $37–132/t CO2 for biochar-CCS supported by policies, such as EPR, carbon credits, and MRV standards. Challenges include land use, competition for feedstocks, and scalability in the Global South, IRS opacity, and the use of AI (digital twin) and interdisciplinary research. The chapter encourages the integrated waste-carbon systems for the low-carbon future, where policy coherence and innovation are the main characteristics.