# Assessing the Feasibility of Bioscrubbing for Flue Gas Treatment and Sulfur Recovery: A Comparative Study Using Mathematical Modeling, Life Cycle Analysis, and Life Cycle Costing

## TL;DR

This study compares chemical and biological scrubbers for treating sulfur-rich flue gas, finding that bioscrubbers can be more sustainable if using the right carbon source.

## Contribution

A holistic comparison of chemical and bioscrubbing methods using mathematical modeling, LCA, and LCC for sulfur recovery.

## Key findings

- Bioscrubbers using purified crude glycerol outperform chemical scrubbers in several environmental impact categories.
- Carbon source purchase dominates bioscrubber costs, with glycerol prices and biogas valorization key to feasibility.
- Sensitivity analyses highlight gas flow rate and disposal site distance as critical factors for bioscrubber viability.

## Abstract

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.