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Bacterial Reduction of Toxic Hexavalent Chromium and its Application to Biological Treatment of Waste Waters

有毒六价铬的细菌还原及其在废水生物处理中的应用

基本信息

批准号：
01550753
负责人：
OHTAKE Hisao
金额：
$ 1.09万
依托单位：
Hiroshima University (1990)The University of Tokyo (1989)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

Hexavalent chromiun (chromate : CrO_4^<2->) is toxic and mutagenic for most organisms. Waste waters containing toxic chromate are generated in many industrial processes. We have isolated a chromate-reducing bacterium, identified as Enterobacter cloacae, from activated sludge. Reduced chromium (Cr^<3+>), which is much less toxic than chromate, readily formed insoluble chromium hydroxides at a neutral pH. The ability of this bacterium to reduce chromate was examined for detoxification and removal of toxic chromium from waste waters.The important features of the reduction kinetics were : (1) the rate of reduction was proportional to cell density ; (2) high concentrations of chromate inhibited the reduction ; (3) the effect of temperature followed the Arrhenius equation over the temperature range of 10-30C ; (4) the reduction occurred at pH6.5 and 8.5 ; (5) the reduction rate was dependent on the amount of added carbon and energy sources ; (6) the reduction of chromate was sensitive to oxygen stress, but when released from the oxygen stress, it readily resumed.E. cloacae strain HOl could reduce toxic chromate in a contaminated industrial effluent. Carbon and energy sources were required for the reduction of chromate. Chromate reduction was inhibited to some extent by other metal ions including Cu^<2+>, Mn^<2+> and Zn^<2+>.This method requires neither high energy nor chemical reagents. It can be said that there is a potential for establishing a cost effective method to remove toxic chromate from contaminated waters.

六价铬（铬酸盐：CrO_4^<2->）对于大多数生物体来说是有毒的和致突变性的。许多工业过程中都会产生含有有毒铬酸盐的废水。我们从活性污泥中分离出了一种铬酸盐还原细菌，被鉴定为阴沟肠杆菌。还原铬(Cr 3+ )的毒性比铬酸盐小得多，在中性pH下很容易形成不溶性氢氧化铬。检测了该细菌还原铬酸盐的能力，用于解毒和去除废水中的有毒铬。还原动力学的重要特征是：（1）还原速率与细胞密度成正比； (2)高浓度的铬酸盐抑制还原； (3)在10-30℃温度范围内，温度的影响遵循阿伦尼乌斯方程； (4)在pH6.5和8.5时发生还原反应； (5) 减少率取决于添加的碳量和能源； (6)铬酸盐的还原反应对氧胁迫敏感，但当氧胁迫解除后，铬酸盐的还原反应又容易恢复。泄殖腔菌株 HOl 可以减少受污染工业废水中的有毒铬酸盐。铬酸盐的还原需要碳和能源。 Cu^2+、Mn^2+、Zn^2+等其他金属离子对铬酸盐还原有一定的抑制作用。该方法不需要高能量，也不需要化学试剂。可以说，有可能建立一种经济有效的方法来去除污染水中的有毒铬酸盐。