Current and future perspectives of valorization of abundant agricultural wastes in Latin America (cocoa pod husks, coconut shells, rice hulls and sugarcane bagasse) by fungal cultivation and methane production by anaerobic digestion: A comprehensive review

Agricultural lignocellulosic wastes from cocoa, coconut, rice and sugarcane processing in Latin America are abundant but often mismanaged, primarily through open burning and uncontrolled disposal. This is unacceptable from an environmental sustainability and circular bioeconomy perspective, although traditional local uses such as limited applications as organic fertilizer, mulch, rudimentary animal feed, or domestic fuel may exist in some rural contexts. The result is environmental pollution, health hazards and greenhouse gas emissions. The primary objective of this comprehensive review is to critically evaluate the integrated valorization of these wastes (cocoa pod husks (CPH), coconut shells (CS), rice hulls (RH) and sugarcane bagasse (SB)) through fungal solid-state fermentation (SSF) as a low-cost biological pre-treatment for anaerobic digestion (AD) and methane production, while generating edible mushrooms and biotechnological enzymes as co-products. Fungal SSF achieves 3–40% delignification and 20–51% Biochemical Methane Potential (BMP) improvement (190–360 L CH4 kg−1 VS) but faces enzymatic trade-offs and rural scalability challenges in Latin America. Future perspectives prioritize enzyme engineering, decentralized pilots and life cycle assessment to enhance regional bioeconomy potential.

This paper reviews the valorization of crop wastes produced on a large scale in America
CPH, CS, RH, and SB have high lignocellulosic content and recalcitrant properties
Low-cost processes such as the production of edible fungi and methane by AD are reviewed
The cultivation of edible fungi from these wastes represents a promising alternative
Hydrothermal pre-treatments increase the anaerobic biodegradability of these wastes

This paper reviews the valorization of crop wastes produced on a large scale in America
CPH, CS, RH, and SB have high lignocellulosic content and recalcitrant properties
Low-cost processes such as the production of edible fungi and methane by AD are reviewed
The cultivation of edible fungi from these wastes represents a promising alternative
Hydrothermal pre-treatments increase the anaerobic biodegradability of these wastes