微生物矿化修复重金属污染土壤

以选矿厂附近土壤为研究对象,分析了土壤中交换态重金属含量,As、Pb、Cd、Zn和Cu的交换态浓度为14.01、4.95、0.64、33.46和12.95 mg/kg。基于生物矿化原理,利用碳酸盐矿化菌生长代谢过程产生的脲酶来分解底物尿素,产生碳酸根离子,固结重金属离子,使得土壤中活泼的重金属离子转变为碳酸盐矿物态,降低其危险。研究了温度、pH和重金属离子对酶活性的影响,发现环境30℃温度有利于促进酶活性;在弱酸性条件下,底物分解量减少15%;重金属离子在低浓度时对脲酶活性影响不大,浓度提高后对酶活性抑制作用没有加剧。将制备好的微生物矿化修复制剂喷洒于1 000 m2的污染土壤中,实验结果发现,土壤中交换态重金属离子含量在0～20 cm范围内明显减少,As、Pb、Cd、Zn和Cu的交换态浓度分别减少至2.37、1.25、0.31、16.67和3.42 mg/kg。

Remediation of heavy metal contaminated soils by bacteria biomineralization

The soil near the concentration plant was analyzed, while the contents of exchangeable As,Pb,Cd,Zn and Cu contents were 14.01,4.95,0.64,33.46 and 12.95 mg/kg, respectively. Based on the theory of biomineralization, the heavy metal ion was mineralized as stable carbonate to reduce the risk by the CO₃^2- decompounded by the enzyme effect of carbonate-mineralization microbe. Effects of temperature, environment pH and heavy metals on the enzyme activity were studied. The results indicated that the higher temperature was helpful to enhance enzyme activity. In weak acidic medium, the decomposition quantity of the substrate decreased by 15%. The heavy metal at low concentration had a weak effect of inhibition on enzyme activity while the inhibition did not get worse at high concentration. The prepared microorganisms were sprayed on the polluted soil. The results showed that the contents of exchangeable heavy metals in soil decreased obviously and the contents of exchangeable As,Pb,Cd,Zn and Cu were 2.37,1.25,0.31,16.67 and 3.42 mg/kg, respectively.