Degradation of hydrogen sulfide by immobilized Thiobacillus thioparus in continuous biotrickling reactor fed with synthetic gas mixture

• Immobilized Thiobacillus thioparus was applied for H2S elimination.
• The applicability of continuous biotrickling reactor was demonstrated.
• Bioreactor performance under microaerobic conditions was assessed.

In this work, a sulfur-oxidizing bacteria, Thiobacillus thioparus (immobilized on Mavicell B support) was employed to develop a microaerobic, biotrickling filter reactor for the efficient elimination of H2S from synthetic (bio)gas. To test the capability of this particular strain in oxygen-limited atmosphere, fixed bed reactor was operated under 0.25–5 vol.% O2 concentrations and its H2S decomposing ability was statistically evaluated. It was found that the system achieved 100% H2S elimination efficiency when at least 2.5 vol.% oxygen was provided. Further decrease of O2 levels to 0.25–1 vol.% cut the reliability and caused the loss of H2S biodegradation performance. The results of this study contributed to understand the behavior of T. thioparus under microaerobic conditions and thus may help to design efficient gas purification processes for biogas technology.