Microbal Degradation Of Perchlorate By Different Carbonsource In Groundwater

Perchlorate(ClO4-) has been detected in the soil and groundwater. Exposure to perchlorate can pose a potential threat to the human health. The acceptable safe level of exposure, as stated by the U.S. Environmental Protection Agency, is 0.7 μg perchlorate/kg/day. Therefore, how to remove perchlorate contamination in the environment has aroused concern.In this paper, the main objective of this laboratory research was to carry out the microbiological method to remove perchlorate from groundwater. This study could give a better understanding on perchlorate reduction with different carbon source. The main results of this study are as follows:(1) The cultivation system with different carbon source, and compare the efficiency of removal perchlorate from contaminated groundwater with different carbon sources. The results showed that the system with rice straw as carbon source has the highest efficiency to remove perchlorate.(2) When the sulfate, nitrate, perchlorate exist at the same time. Nitrate is removed firstly, then the perchlorate, sulfate slowest. The reason is due to how easy the microbial use these three electron acceptor. All of that give the theoretical basis for practical application of microbial remediation technologies in the restoration field of perchlorate-contaminated environments.(3) Through the control experiment, both of the perchlorate reducing bacteria and cellulose decomposing bacteria are from soil. But in the original environment, these two kinds of microorganisms are not the dominant species, the detection is less than 1%.(4) Small molecular weight of carbon source is easy to use. But when there are other microorganisms in the contaminated soil, small carbon source is more favorable for other microbial growth and inhibits perchlorate reducing bacteria growth.(5) The carbon source is the main factor affecting the perchlorate reduction. But in the groundwater environment, rice straw also as a carrier for microbial attachment and growth, thus increase the perchlorate removal efficiency.