Sulfide oxidation at halo-alkaline conditions in a fed-batch bioreactor
✍ Scribed by Pim L.F. van den Bosch; Otto C. van Beusekom; Cees J.N. Buisman; Albert J.H. Janssen
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 342 KB
- Volume
- 97
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Abstract
A biotechnological process is described to remove hydrogen sulfide (H~2~S) from high‐pressure natural gas and sour gases produced in the petrochemical industry. The process operates at halo‐alkaline conditions and combines an aerobic sulfide‐oxidizing reactor with an anaerobic sulfate (SO) and thiosulfate (S~2~O) reducing reactor. The feasibility of biological H~2~S oxidation at pH around 10 and total sodium concentration of 2 mol L^−1^ was studied in gas‐lift bioreactors, using halo‐alkaliphilic sulfur‐oxidizing bacteria (HA‐SOB). Reactor operation at different oxygen to sulfide (O~2~:H~2~S) supply ratios resulted in a stable low redox potential that was directly related with the polysulfide (S) and total sulfide concentration in the bioreactor. Selectivity for SO formation decreased with increasing S and total sulfide concentrations. At total sulfide concentrations above 0.25 mmol L^−1^, selectivity for SO formation approached zero and the end products of H~2~S oxidation were elemental sulfur (S^0^) and S~2~O. Maximum selectivity for S^0^ formation (83.3±0.7%) during stable reactor operation was obtained at a molar O~2~:H~2~S supply ratio of 0.65. Under these conditions, intermediary S plays a major role in the process. Instead of dissolved sulfide (HS^−^), S seemed to be the most important electron donor for HA‐SOB under S^0^ producing conditions. In addition, abiotic oxidation of S was the main cause of undesirable formation of S~2~O. The observed biomass growth yield under SO producing conditions was 0.86 g N mol^−1^ H~2~S. When selectivity for SO formation was below 5%, almost no biomass growth was observed. Biotechnol. Bioeng. 2007; 97: 1053–1063. © 2007 Wiley Periodicals, Inc.