Restrictive factors and their effects on microbial sulfate-reducing phase during flue gas desulfurization

Abstract:

[Objective] Sulfate reducing bacteria (SRB) anaerobic activated sludge was used in the process of flue gas desulfurization. This study aimed on the exploring optimal conditions for SRB to carry out sulfate bio-reduction, and analyze the impacts of heavy metal ions on sulfate bio-reduction. [Methods] The SRB anaerobic activated sludge obtained from an anaerobic sludge pool was domesticated under high sulfate concentration. The restrictive factors suppressing sulfate bio-reduction ability of SRB anaerobic sludge was investigated during the flue gas desulfurization. [Results] The domesticated SRB anaerobic activated sludge had a strong ability of sulfate reduction in a optimal culture condition (pH 6.5 and 32 °C). The function of sulfate reduction was obviously enhanced with additional Fe2+. In the sulfate reduction process, the optimum value of ThCOD/SO42? and ThCOD (theoretical chemical oxygen demand) were found of 3.00 and 3.33, respectively, and the sulfate reduction rate reached 72.15%. The activity of SRB was suppressed by 300 mg/L sulfide in the system of sulfate reduction. The heavy metal ions, Ni2+ and Pb2+, showed strong inhibition on SRB sulfate reduction ability at the level of 1.0 mg/L and 2.0 mg/L, respectively, meanwhile, Cu2+ inhibition at rather higher concentration (8.0 mg/L). [Conclusion] After domestication, the SRB anaerobic activated sludge shows a strong sulfate reducing function under optimal conditions, and it would be of great industrial potential for flue gas bio-desulfurization. In addition, the heavy metal ions which have negative impacts must be removed to ensure the efficient sulfate bio-reduction.

Key words:Sulfate reducing bacteria, Biological flue gas desulfurization, Anaerobic activated sludge, Heavy metal ions