A review on the removal of hydrogen sulfide from biogas by adsorption using sorbents derived from waste

Abstract

Biogas is a vital renewable energy source that could play an effective role in fulfilling the world's energy demand, not only in heat and power generation but also as a vehicle fuel in the future. Unfortunately, due to impurities, biogas requires a series of upgrading steps, which affects its economics and sustainability. Hydrogen sulfide (H2S) is one of the impurities that economically and environmentally hinder the biogas utilization as a source of energy. H2S removal from biogas using different technologies was extensively studied and established. One of such technology is adsorption. Adsorption by solid sorbents is considered as a suitable removal technique for toxic gases such as H2S because of its simplicity, easy handling, and environmental friendly sorbents. In this review, the utilization of waste material-based sorbent for H2S removal was appraised. Other gaseous components of biogas such as siloxanes, CO2,etc., are out of the scope of this work. The potential and effectiveness of the waste-derived sorbents, either raw waste or modified waste, were summarized in terms of its characteristics, suitability, and sustainability. The review provides an insightful analysis of different types of wastes such as sewage sludge, food waste, forestry waste, fly ash, and industrial wastes as an alternative tocommercial adsorbents to adsorb H2S gas. Based on the analysis, it was concluded that ifthese sorbents are to be successfully commercialized, its economic analysis, regeneration conditions, and potential utilization of the spent sorbents has to be further exploited. Nevertheless, thereis a great prospectus in the future for these waste materials to be utilized as sorbents for H2S removal.