微生物烟气脱硫中硫酸盐还原阶段的限制性因素及其影响

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

【目的】利用硫酸盐还原菌(SRB)厌氧活性污泥进行烟气脱硫,探索硫酸盐生物还原的最适条件及重金属离子对硫酸盐生物还原的影响,以提高硫酸盐还原阶段的效率。【方法】对取自污水处理厂的SRB厌氧活性污泥进行高浓度硫酸盐胁迫驯化。分析生物脱硫过程中SRB厌氧污泥还原硫酸盐的限制性因素及影响。【结果】在最适生长条件下(pH 6.5,32°C),经驯化获得的SRB厌氧活性污泥有较强的硫酸盐还原能力。Fe2+的适量添加对硫酸盐还原有一定促进作用。SRB厌氧污泥还原硫酸盐的ThCOD/SO42-最适值为3.00,ThCOD=3.33为最适理论化学需氧量,硫酸盐还原率可达72.15%。SRB厌氧污泥还原硫酸盐反应体系中抑制SRB活性的硫化物浓度为300 mg/L。Pb2+和Ni2+在较低的浓度下(1.0 mg/L和2.0 mg/L)对硫酸盐的还原产生较强的抑制作用,而Cu2+在稍高的浓度下(8.0 mg/L)显示出明显的抑制作用。【结论】经驯化,SRB厌氧活性污泥显示出较强的硫酸盐还原能力,具有应用于工业烟气生物脱硫的潜力。去除重金属离子Pb2+、Ni2+和Cu2+可有效解除对硫酸盐生物还原作用的抑制。

[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 thesulfate 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.