氢基质自养微生物还原降解水中溴酸盐的可行性

Feasibility of Bioreductive Degradation of Bromate in Water by Autohydrogenotrophic Microorganisms

BrO_3^-(溴酸盐)作为饮用水中存在的2B级潜在致癌物已引起社会公众的广泛关注.微生物还原降解是一种净化水中BrO_3^-的有效途径.基于序批式试验,研究了厌氧条件下微生物利用氢气作为电子供体还原降解水中BrO_3^-的可行性及关键影响因素.结果表明,氢自养微生物能利用氢气为电子供体、BrO_3^-为电子受体,将BrO_3^-完全还原成一种稳定的无毒的终产物Br^-.在120 h的反应期内,ρ(BrO_3^-)从初始时的1.02 mg/L降至0.56 mg/L(去除率为44.5%),最高去除速率达0.26 mg/(L·d),出水ρ(Br^-)相应地升至0.29 mg/L.对照处理中,ρ(BrO_3^-)和ρ(Br^-)均没有明显的降低和升高趋势.影响因素试验表明,NO_3^--N和SO_4^(2-)作为常规氧化性污染物(电子受体),反硝化和SO_4^(2-)还原对BrO_3^-还原耗氢产生了竞争,致使BrO_3^-生物还原过程受到电子供体的竞争性抑制.反硝化对BrO_3^-还原效率的影响程度比SO_4^(2-)还原更加强烈.初始ρ(BrO_3^-)对氢自养微生物还原降解BrO_3^-效率有较大影响.氢自养微生物还原降解BrO_3^-最适宜的pH范围处于7.0~7.5之间.研究显示,利用氢气作为电子供体的氢自养微生物将BrO_3^-还原成无毒的Br^-是一种较为可行的生物处理技术或手段.

Bromate （BrO_3 - ） as a possible human carcinogen （Group 2B） in drinking water attracts extensive public concern. Microbial reduetive degradation is an effective pathway to remove bromate from water. The feasibility and influencing factors of bromate biodegradation by microorganisms using hydrogen as an electron donor were investigated under anaerobic conditions based on bath experiments. The results showed that bromate can be bioreduced to bromide （Br-） as a stable non-toxic ultimate product by autohydrogenotrophic microorganisms using hydrogen as the electron donor and bromate as the electron aceeptor. During a period of 120 hours, bromate concentration was reduced from initial 1.02 to 0.56 mg/L （ removal efficiency of 44.5% ） with a maximum removal rate up to 0. 26 mg/（ L · d） , corresponding to effluent bromide concentration rising to 0. 29 mg/L. However, neither bromate nor bromide concentration showed significant decrease or increase in the controls. The results obtained from the investigation of influencing factors revealed that nitrate （ NO_3 - -N） and sulfate （ SO_4 2- ） were conventional oxidized contaminants （ electron acceptors） , while denitrification and sulfate reduction caused a competition for hydrogen consumption by bromate reduction, and these generated an inhibition on the bioreduction of bromate. Denitrification affected bromate reduction efficiency more strongly than sulfate reduction. The initial concentration of bromate had a great influence on degradation efficiency. The appropriate pH range from 7.0 to 7.5 was most suitable for autohydrogenotrophic microorganisms to degrade bromate. The reduction of bromate to non-toxic bromide using autohydrogenotrophic microorganisms with hydrogen as the electron donor is a feasible biological treatment technology, and it will provide a theoretical reference for membrane biofilm reactor （MBfR） treating bromate-polluted water.