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In anaerobic wastewater treatment processes, the presence of sulfate-reducing bacteria (SRB) produces hydrogen sulfide (H2S). Hydrogen sulfide is a common component in landfill, wastewater treatment and dairy plant off-gases (e.g., biogas) as well as other digester gas plants. Environmental laws regulate the release of this toxic, odorous gas into the atmosphere. The corrosive nature of this gas can result in costly damage to process equipment and biogas handling piping systems.
Prior to recent environmental regulations, the simplest means of dealing with H2S was to burn the biogas in a flare before atmospheric release. Flaring biogas typically achieves only 95 percent conversion of H2S to non-odorous sulfur dioxide (SO2). However, this level of H2S removal is insufficient to meet most air quality requirements. Additionally, sulfur dioxide emissions are strictly regulated.
Previous technologies used to remove H2S from biogas to obtain H2S-free biogas were not cost effective. Additionally, they lacked efficient levels of H2S removal. While flaring is insufficient to meet emission limits, other physico-mechanical treatment methods such as iron sponges, other iron-based absorbents, chemical scrubbers and water scrubbers, sulfur recovery processes and sulfatreat are excellent options.
Western Biogas Systems designs and builds H2S removal systems based on client specific inlet gas conditions, utilizing outcome efficient, cost effective technologies. Capital costs and product usage benefits for each client are paramount in the selection of the appropriate technology.