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Removal of Hydrogen Sulfide from Biogas Using a Bubbling Tank Fed with Aerated Wastewater

Category: Technical Note

Volume: 20 | Issue: 3 | Pages: 643-653
DOI: 10.4209/aaqr.2019.12.0647
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To cite this article:
Ou, H.W., Chou, M.S. and Chang, H.Y. (2020). Removal of Hydrogen Sulfide from Biogas Using a Bubbling Tank Fed with Aerated Wastewater. Aerosol Air Qual. Res. 20: 643-653. doi: 10.4209/aaqr.2019.12.0647.

Hsiu-Wen Ou1, Ming-Shean Chou2, Hsiao-Yu Chang 1

  • 1 Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
  • 2 Livestock Research Institute, Council of Agriculture, Executive Yuan, Tainan 71246, Taiwan

Highlights

  • The study developed a scrubber for removing over 80% of H2S in a biogas.
  • Increasing scrubbing liquid pH to 8.0 improved the H2S removal efficiency to 99%.
  • CO2 in the biogas is responsible for the pH decrease of the scrubbing liquid.

Abstract

The work develops a simple bubbling tank scrubber that is fed with aerating wastewater for the removal of hydrogen sulfide (H2S) in biogas. A 2,000 L plastic tank, in which fixed liquid levels 0.80 and 1.0 m and volumes of 1.1 and 1.4 m3 was kept, was used for the scrubbing tests. A polyvinyl chloride (PVC) pipe with holes of 1 mm diameter was used to sparge the biogas into the tank liquid. Results indicate that with an influent liquid of pH 7.5–7.7, a flow rate of 23–25 L min–1, influent biogas flow rates of 0.050–0.200 m3 min–1, and a H2S concentration of 907 ± 212 ppm, the pH of the effluent liquid stabilized at 6.6–6.9. With gas/liquid rate ratio of 2–8 m3 m–3 liquid and volumetric gassing intensities of 0.04–0.20 m3 m–3 liquid min–1, average H2S removals of 86–71% were obtained. Absorption of CO2 in the tested digester gas into the scrubbing liquid caused a decrease in the pH, thus decreasing the H2S removal efficiency. Increasing pH of the scrubbing liquid to 8.0 improved the H2S removal efficiency to as high as 99%.

Keywords

Hydrogen sulfide Bubbling scrubbing Digester gas Air pollution control


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