A novel and cost-effective hydrogen sulfide removal technology using tire derived rubber particles
Is Version Of
Hydrogen sulfide (H2S) is corrosive, toxic, and produced during the anaerobic digestion process at wastewater treatment plants. Tire derived rubber particles (TDRPTM) and other rubber material (ORMTM) are recycled waste rubber products distributed by Envirotech Systems, Inc (Lawton, IA). They were found to be effective at removing H2S from biogas in a previous study. A scrubber system utilizing TDRPTM and ORMTM was tested at the Ames Water Pollution Control Facility (WPCF) to determine operational conditions that would optimize the amount of H2S removed from biogas in order to allow for systematic sizing of biogas scrubbers.Operational conditions tested were empty bed contact time, mass of the media bed, compaction of the media bed, and temperature of the biogas and scrubber media. Additionally, siloxane concentrations were tested before and after passing through the scrubber. The two different types of products, TDRPTM and ORMTM, differed in metal concentrations and particle size distribution. A scrubber system was set up and maintained in the Gas Handling Building at the WPCF from February to December 2009. Results showed that longer contact times, compaction, and higher inlet H2S concentrations improved the amount of H2S that was adsorbed by the TDRPTM and ORMTM. The inlet H2S concentration of the biogas was found to be variable over time and was affected by large additions of fats, oils, and grease (FOG). The effect of temperature was not found to be significant. In excess of 98% siloxane reduction was observed from the biogas.The Freundlich Isotherm was successfully fit to experimental data at ambient temperatures (near 25°C) and low temperatures (14-20°C). Using assumptions about the concentration of H2S, flow of biogas, and temperature at the WPCF, it was found that the volume of ORMTM and TDRPTM needed for one year of H2S removal at the WPCF at 25°C would be approximately 12.48 m3 and 6.77 m3, respectively.