Development of bioremediation and biorefinery process for rare metal using metal-oxoanion reducing and accumulating bacteria

为了防止高科技行业日益消耗的稀有金属对环境的污染和消耗，筛选出新型稀有金属还原聚集菌，并将其应用于稀有金属的去除/回收过程。第一年，利用芽孢杆菌SF-1菌株开发了含硒废水处理反应器，该菌可以通过亚硒酸盐将硒还原为元素硒。含1-2 mM亚硒酸盐的模拟废水在水力停留时间不到1d的情况下，结合简单的混凝沉淀或超滤可以完全去除和回收元素硒。第二年，对芽孢杆菌SF-1的砷还原能力进行了详细的表征，并对利用芽孢杆菌SF-1对砷污染土壤进行生物修复的可行性进行了评价。芽孢杆菌SF-1菌株能利用多种碳源，对S…的厌氧条件要求不高更多的伦酸减少。这些特点对实际的生物修复过程具有显著的效益。此外，芽孢杆菌SF-1在亚硒酸盐和硝酸盐共存的情况下也能还原砷。因此，芽孢杆菌SF-1具有单独的还原酶，分别被砷、硒和硝酸盐诱导。最后一年，进行了实验室规模的浆态相间歇反应器实验。证实了芽孢杆菌SF-1菌株既不需要高接种量，也不需要搅拌。因此，研究了一种低成本的连续土壤填充柱反应器来处理模型砷污染土壤。该反应器在接种液水力停留时间为1d的条件下，结合磷酸盐缓冲液的冲洗，可将模型砷污染土壤(300 mg-As/kg土)净化至低于土壤砷含量标准(150 mg-As/kg土)。这表明利用金属氧阴离子还原/聚集菌开发砷的去除/回收工艺是可行的。较少

For the prevention of environmental pollution by and exhaustion of rare metals which are increasingly consumed in high-tech industries, novel rare metal reducing and accumulating bacteria were screened and applied to rare metal removal/recovery processes.In the first year, selenate containing wastewater treatment reactor was developed utilizing Bacillus sp.SF-1 which can reduce selenate to elemental selenium via selenate. Model wastewater containing 1-2 mM selenate could be treated with less than 1 day of the hydraulic retention time, and elemental selenium was completely removed and recovered when combining with simple coagulation sedimentation or ultrafiltration.In the second year, arsenate reduction ability of Bacillus sp.SF-1 was characterized in detail and the feasibility of the bioremediation process for arsenate contaminated soil utilizing Bacillus sp.SF-1 was evaluated. Bacillus sp.SF-1 could utilize various carbon sources and did not require stringent anaerobic condition for s … More elenate reduction. These characteristics were remarkable benefit for the actual bioremediation process. In addition, Bacillus sp.SF-1 could reduce arsenate even selenate and/or nitrate were coexisting. Thus, it was implied that Bacillus sp.SF-1 has separate reductases which are individually induced by arsenate, selenate and nitrate.In the final year, lab-scale slurry phase batch reactor experiment was performed. It was confirmed that both high-inoculum concentration of Bacillus sp.SF-1 and agitation were not needed. Therefore, continuous soil packed column reactor, which allows low cost treatment, was investigated to treat model arsenate contaminated soil. This reactor could purify the model arsenate contaminated soil (300 mg-As/kg-soil) to below a soil content standard of arsenate (150 mg-As/kg-soil) with hydraulic retention time of inoculum culture fluid at 1 day when combined with washing by phosphate buffer.These results indicate the feasibility of the development of arsenate removal/recovery process utilizing metal-oxoanion reducing/accumulating bacteria. Less