Biofuel Production from Sericulture by Products: Pathways, Technologies, and Sustainability Perspectives

The sericulture industry, primarily focused on silk production, generates substantial quantities of organic residues including mulberry prunings, silkworm litter, pupae, defective cocoons, and sericin-rich wastewater. These by-products, often underutilized or disposed of in environmentally detrimental ways, hold significant potential for biofuel production and integration into circular bioeconomy frameworks. This review synthesizes recent advances in the biochemical characterization, energy potential, and conversion technologies applicable to sericulture residues. Biochemical processes such as enzymatic hydrolysis and anaerobic digestion enable bioethanol and biogas production, while thermochemical methods, including pyrolysis, gasification, and hydrothermal liquefaction, can convert dry and protein-rich residues into syngas, bio-oil, biochar, and bio-crude. Integrated biorefinery approaches that combine biodiesel from pupal lipids with ethanol and methane production from lignocellulosic and proteinaceous residues maximize energy recovery and reduce environmental impacts. Techno-economic assessments indicate that decentralized processing and cooperative feedstock aggregation enhance feasibility, while life cycle analyses demonstrate substantial greenhouse gas mitigation and soil health improvement through digestate and biochar applications. Despite challenges such as feedstock seasonality, high free fatty acid content in pupal oil, and regulatory gaps for insect-derived fuels, policy incentives, quality certification, and targeted R&D can accelerate adoption. Sericulture-based biofuels offer a pathway toward sustainable rural energy systems, resource efficiency, and waste valorization.