Microbial degradation of organic pollutants in groundwater related to underground coal gasification

Groundwater pollution is regarded as one of the most serious environmental risks related to underground coal gasification (UCG). In this paper, two kinds of high efficient phenol degrading strains were isolated from activated sludges, which were obtained from coking wastewater and domestic sewage, and were named as JC and WX correspondingly. The isolated bacteria were identified by a combination method of physiological and biochemical analyses and 16SrDNA sequencing. The total organic carbon (TOC) and organic pollutants in gas washing water produced from the UCG model test of lignite were measured by TOC analyzer and gas chromatography-mass spectrometer (GC-MS), and the microbial degradation effect of gas washing water was finally studied by the isolated bacteria. The results reveal that JC and WX bacteria were pseudomonas aeruginosa and achromobacter xylosoxidans, respectively, and that phenolic compounds were the main organic pollutants in gas washing water, taking 95.01 percent of the total organics. The removal of TOC exceeded 72.9%, the degradation efficiency of total organic pollutants (TOM) achieved 79.03% and the degradation efficiency of phenolic compounds could be 98.76% by JC and 99.04% by WX, respectively. Most benzene series (BTEX) could not be degraded by the screened two kinds of bacteria, whereas the concentrations of BETX were increased. Some short-chain hydrocarbon compounds with low concentrations were also detected in wastewater after microbial degradation.