Hydrogen Sulfide Removal from Biogas and Sulfur Production by Autotrophic Denitrification in a Gas-Lift Bioreactor

Abstract

Biogas biodesulfurization has been successfully performed in biotrickling filters (BTFs). Nevertheless, elemental sulfur (S 0 ) generation and accumulation in the packed bed cause an increase in operating costs restricting its application. This drawback could be avoided using a gas-lift bioreactor as proposed in the present work, which allows recovery and reuse of the generated S 0 . The effect of governing operational parameters [nitrite concentration, nitrogen/sulfur (N/S) molar ratio, hydraulic residence time (HRT), pH, inlet load (IL), and gas residence time (GRT)] was studied. Results showed that no inhibition by nitrite was found at concentrations up to 760 mg N− NO 2 − L −1 . H 2 S removal efficiencies (REs) over 95% were obtained under ILs over 55 g S−H 2 S m −3 h −1 when N/S molar ratios of 1.1 mol mol −1 or above were used. A HRT of 36 h and a pH of 7.8 ± 0.05 were found to be optimal. The maximum S 0 production (99%) was obtained under an IL of 180 g S−H 2 S m −3 h −1 using a N/S molar ratio of 1.1 (RE = 98.1 ± 0.5%). A maximum elimination capacity of 194.2 ± 4.2 g S−H 2 S m −3 h −1 (RE = 83.9%) was obtained under a GRT of 41 s. Therefore, gas-lift bioreactors stand as a successful and feasible alternative to BTFs to accomplish the anoxic biodesulfurization.

Approaches to mitigation of hydrogen sulfide during anaerobic digestion process – A review

“… Optimal pH range of 7–8. [ 136 , 137 , 60 ] Biofiltration Contaminated gases are carried into the biofilm and through the biofilter, where microbes use them as carbon or energy source. The H2S is further broken down to produce sulfate or sulfuric acid.…”

Photoautotrophic removal of hydrogen sulfide from biogas using purple and green sulfur bacteria

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