Agro-industrial residues as biofilter media for biogas desulfurization: An alternative to activated carbon

Biogas desulfurization is essential to prevent equipment corrosion and ensure its suitability for energy applications. Although several technically established desulfurization technologies are commercially available, their implementation may still be constrained by acquisition costs, operational expenses, and environmental impacts associated with the use of conventional materials such as activated carbon. In this context, this study investigates the potential of two abundant agro-industrial residues - Luffa cylindrica and Carya illinoinensis - as low-cost and environmentally favorable filter media for biofilters applied to biogas desulfurization. A pilot-scale system operated for 62 days treating biogas with H₂S concentrations above 5000 ppm, and their performance was compared with that of a conventional activated carbon filter. Both biofilters demonstrated high initial removal efficiencies, reducing H₂S concentrations in the treated gas to below 20 ppm. Over time, the loofah-based filter showed a decline in performance due to sulfur accumulation, whereas the pecan shell medium exhibited greater operational stability and indications of self-regeneration, achieving performance statistically comparable to that of activated carbon. These results highlight the technical feasibility of using abundant agro-industrial biomass as alternative biofilter media, contributing to reduced operational costs and lower environmental impacts in biogas purification systems. The findings also reveal opportunities for integrating biomass waste valorization with biogas purification technologies, indicating promising pathways for more sustainable and economically accessible desulfurization strategies in decentralized and industrial biogas applications.