Maximizing elemental sulfur production using an enriched sulfur-oxidizing bacterial consortium in a fed-batch...

Area of Science:

• Environmental biotechnology
• Biochemical engineering
• Industrial microbiology

Background:

• Conventional physicochemical methods for hydrogen sulfide (H₂S) removal are often costly and less sustainable.
• Biological desulfurization presents a promising eco-friendly alternative for industrial gas streams.
• Sulfur-oxidizing bacteria (SOB) can selectively convert sulfide to elemental sulfur.

Purpose of the Study:

• To enrich and apply a sulfur-oxidizing bacterial (SOB) consortium for selective biological desulfurization.
• To optimize process parameters for maximizing elemental sulfur production and minimizing by-products.
• To evaluate the efficiency of biological desulfurization in a fed-batch airlift bioreactor.

Main Methods:

• Isolation and enrichment of SOB consortium from sulfur-rich environments.
• Utilized Central Composite Design-Response Surface Methodology (CCD-RSM) for process optimization.
• Fed-batch airlift bioreactor operated under controlled dissolved oxygen (DO), pH, and sulfide loading rates.

Main Results:

• Low DO levels (0.2 mg L⁻¹) favored elemental sulfur production.
• Optimal conditions determined: pH 8.5, DO 0.2 mg L⁻¹, sulfide loading rate 97.2 mg L⁻¹ h⁻¹.
• Achieved 71% selective conversion to elemental sulfur and 100% sulfide removal.

Conclusions:

• Enriched SOB consortia and optimized bioreactor conditions enhance biodesulfurization efficiency and selectivity.
• The optimized biological process is cost-effective, sustainable, and operates under mild conditions.
• This method offers a viable and environmentally friendly alternative to conventional H₂S removal techniques.