铬渣的细菌解毒实验研究

The Research of Detoxification on Chromium-containing Slag by Bacteria

采用从铬渣堆埋场附近的污泥中分离到的高效还原Cr(VI)的Ch-1菌进行细菌浸出的摇瓶实验,分别考察了不同液固比,温度,初始pH值情况下浸出液的pH值变化,Cr(VI)浓度变化及浸出过程铬渣中六价铬的浸出率变化和最终渣浸出毒性。实验结果表明,在细菌的作用下,浸出液Cr(VI)浓度均能解毒为0ppm,同时,浸出液pH值降低到8~9之间,细菌浸出渣毒性降低到0.05ppm以下,远低于GB5085.3-1996危险废物浸出毒性鉴别标准1.5ppm。同时,渣中的Cr(VI)也大部分被有效浸出后还原为Cr(Ⅲ)沉淀。特别是在液固比10:1,温度28℃,初始pH=10.0的条件下,铬渣中六价铬浸出率达到了95.43%,同时浸出液pH值=8.20,Cr(VI)浓度为0ppm,浸出渣浸出毒性0.007 ppm,均达到国家排放标准,取得了较好的解毒效果。

Bottle experiments are conducted by effective Cr(Ⅵ)-detoxification bacteria isolated from sludge nearby the chromium-containing slag site.The effects of processing conditions,such as liquid to solid ratio,temperature,and initial pH on the leaching rate,leaching toxicity of the slag and characteristics of leaching solution(pH value and Cr(VI) concentration) are detected in the experiment.The results show that the Cr(VI) concentration of leaching water can deoxidized to 0ppm;the pH value reduced to 8～9;and the leaching toxicity of the slag reduced to less than 0.05ppm,deeply under leaching toxicity standard GB5085.3-1996. At the same time,the great mass of Cr(VI) is leached and reverted to Cr(Ⅲ) deposition.when the liquid to solid ratio is 10∶1,temperature is 28℃,and the initial pH is 10.0,the leaching rate of the Cr(VI) reached 95.43%,at the same time,pH value of solution is 8.20,and Cr(VI) concentration of solution is 0ppm,all of them are below the national discharging standard and acquire ideal result of detoxification.