Assessing the Feasibility of Bioscrubbing for Flue Gas Treatment and Sulfur Recovery: A Comparative Study Using...

Industrial flue gas emissions are treated with technologies such as wet flue gas desulfurization (FGD) in chemical scrubbers, which are costly. Two-step biological scrubbers have emerged as an alternative for bio-FGD. However, no holistic technoeconomic and environmental comparison of both approaches is yet available. This study evaluates a conventional chemical scrubber (CS) and a bioscrubber (BS) treating sulfur-rich off-gas from a sulfur-based pigment plant. The bioscrubber integrates anaerobic sulfate reduction and partial sulfide oxidation to recover elemental sulfur and biogas. Two BS variants were analyzed, differing in carbon source for sulfate reduction: fossil-derived pure glycerin (BS-PG) and purified crude glycerol (BS-PCG). Mathematical models were integrated with life cycle assessment (LCA) and life cycle costing (LCC). Bioscrubbing enables resource recovery but strongly depends on the carbon source: BS-PG raises environmental impacts in most categories and increases greenhouse gas emissions to about 7277 tCO₂eq per year, compared with 1379 tCO₂eq for CS, whereas BS-PCG limits them to 1599 tCO₂eq and performs better than CS in several impact categories. Nonetheless, the energy and chemical demands for glycerol purification remain challenging. Sensitivity analyses identified gas flow rate, purge fraction, and distance to disposal sites as crucial parameters, indicating that bioscrubbing may be suited for medium-to-small plants. Economic analysis indicates that carbon source purchase dominates costs (≈1.6 M€/year for BS-PG and 1.2 M€/year for BS-PCG), so feasibility hinges on lowering glycerol prices and valorizing biogas. Overall, the integrated assessment highlights key trade-offs and design levers for enhancing the sustainability and viability of bioscrubber systems.