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

为防止高技术产业中日益消耗的稀有金属对环境的污染和耗竭，筛选了新型稀有金属还原富集菌，并将其应用于稀有金属的去除/回收工艺。第一年利用芽孢杆菌sp.SF-1开发了含硒废水处理反应器，通过硒酸盐将硒酸盐还原为元素硒。含1 ~ 2 mM硒酸盐的模型废水在水力停留时间不到1天的情况下即可处理，结合简单混凝沉淀法或超滤法均可完全去除和回收元素硒。第二年详细表征了芽孢杆菌sp.SF-1对砷酸盐的还原能力，并评价了芽孢杆菌sp.SF-1对砷酸盐污染土壤进行生物修复的可行性。芽孢杆菌sp.SF-1可以利用多种碳源，不需要严格的厌氧条件即可进行高纯度的还原。这些特性对实际的生物修复过程具有显著的益处。此外，芽孢杆菌sp.SF-1可以还原砷酸盐，即使硒酸盐和/或硝酸盐共存。提示芽孢杆菌sp.SF-1具有砷酸盐、硒酸盐和硝酸盐分别诱导的还原酶。在最后一年，进行了实验室规模的浆相间歇式反应器实验。结果表明，菌株sf -1无需高接种量和搅拌。为此，采用低成本的连续填料柱式反应器处理砷酸盐污染土壤模型。该反应器可将模型砷污染土壤（300 mg-As/kg-soil）净化至低于砷含量标准（150 mg-As/kg-soil），接种培养液水力滞留时间为1 d，配合磷酸盐缓冲液洗涤。这些结果表明，利用金属氧阴离子还原/富集菌开发砷酸盐去除/回收工艺是可行的。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