A review on value addition of Agricultural Residues by Chemical and Bio-chemical Processes to abate environmental pollution

Agricultural residues, such as crop straws, husks, leaves, and stems, are generated in significant quantities globally, often contributing to environmental pollution when improperly managed. The sustainable utilization of agricultural residues has become a paramount focus in the pursuit of a circular and resource-efficient economy. This review paper provides an extensive analysis of the current state-of-the-art methodologies for extracting value from agricultural residues through chemical/biochemical pretreatment methods. This review explores the potential for adding value to these residues through various chemical and biochemical processes, aiming to mitigate their environmental impact. Chemical processes, including pyrolysis, gasification, combustion, and transesterification, convert biomass into biochar, bio-oil, syngas, and biodiesel, respectively. Biochemical processes, such as anaerobic digestion, fermentation, composting, and enzymatic hydrolysis, produce biogas, biofuels, and soil amendments. These methods not only reduce greenhouse gas emissions and improve waste management but also enhance soil health and promote a circular economy. Despite challenges in technological development, policy support, and public awareness, the integration of these processes within biorefineries holds promise for maximizing resource efficiency and sustainability. This review underscores the importance of continued research and innovation in transforming agricultural residues into valuable products for environmental and economic benefits. • Agricultural residues offer value-added potential in a circular, resource-efficient economy. • Pyrolysis, gasification, and combustion convert residues into fuels like biochar and syngas. • Biochemical methods yield biogas, biofuels, and compost via digestion and fermentation. • Waste valorization cuts emissions and supports sustainable waste management. • Integrating processes in biorefineries boosts resource use and economic gains.