An economic analysis of microbial reduction of sulfur dioxide with anaerobically digested sewage biosolids as electron donor

Conclusions

In summary, it appears that the microbial reduction process is not competitive with conventional SO₂-reduction techniques when AD-MSS medium is used as the feedstock hydrogen source. This is owing not to the intrinsic cost of the medium, but to the low concentration of fermentable substrates in this medium when prepared as previously described (7). The greatest incremental decrease in costs of the microbial SO₂-reduction process would result from a decrease in the hydraulic loading to the bioreactors. Potentially this could be achieved by increasing the concentration of fermentable substrates in the AD-MSS medium through improvements in the anaerobic digestion process by which the medium is produced. Process economics could also be improved by increasing the SRB concentration in the process culture to >30 wt%. This would result in reduced bioreactor volume required and lower capital costs.