Abstract:

Groundwater sciences and engineering developed so far has become a comprehensive discipline involving multiple subjects. Control and remediation of contaminated groundwater need technical and knowledge support from inter-disciplinary effort. Bacterium has been a focus for sustainable remediation of organic contaminated sites. A concise review on groundwater contamination and its remediation, interactions between organic contaminant and microorganisms, bioremediation mechanism, and then bacteria was undertaken. As a case study, a microbial study was carried out at a petroleum contaminated groundwater site to have successfully isolated dominant strains for oil degradation from the oil contaminated groundwater samples. The results showed that the Prokaryotic actinomycetes possessed the best degradation rate, followed by other bacteria and fungi. Pairwise combinations showed obvious better degradation than single bacterium, indicating the presence of synergies. Mixed strains expressed poorer degradation, revealing the antagonistic effect. Dynamics degradation experiment demonstrated TPH degradation follows the 1st order kinetics equation, the degradation rate and half-life of petroleum contamination were obtained. For specific compounds, alkane exhibited the similar degradation to TPH; refractory non-hydrocarbon compounds showed lower degradation rate, it was concentrated later since the transformation of alkanes, little change in benzene. The microbial activity experimental results showed that the biomass and dehydrogenase activity correlated with the biodegradation positively. The specific species of the bacteria were determined by physiobiochemical and molecular biological techniques.

Key words: groundwater, petroleum contamination, microorganism, biodegradation, strain identification, molecular biology