| When the abandoned mine was shutdown, the underground pressure and the ventilation condition was changed. Then the structure and function of the micro ecological environment of the mine will affect the migration and transformation of pollutants. PAHs pollutants, which are produced in oil and emulsifier during the mining period, have three consistency, biological chemicals and refractory high-risk characteristics. In order to ensure the safety of the closed mine groundwater, it is necessary to study the changes of microbial community structure of closed mine groundwater systems, and bioremediation regularity and feasibility of PAHs.In this paper, the distribution characteristics and evolution law of microbial communities in the closed mine water were investigated through the static simulation experiment. An efficient phenanthrene-degrading bacteria, which was isolated from the sediment of the landscape river, is used to investigate the degradation of phenanthrene by different conditions, and to explore the degradation pathway of phenanthrene in groundwater of different abandoned mine closed conditions. The main research contents are as follows.(1)The simulation results of mine closure show that the microbial biomass in two closed environment increased first and then decreased. Under the closed and semi closed conditions, the bacteria were the main microbes in the mine water and gradually increased, and the proportion of fungi and actinomycetes decreased gradually. The number of SRB was increasing in the fully-closed environment, and was decreasing in the semi-closed environment. By bacterial 16 S r DNA diversity analysis, the dominant bacteria in samples was Bacillus and Lactococcus. Aerobic bacteria gradually declined, and anaerobic bacteria increased gradually over time. The diversity of bacteria increased gradually in the fully-closed environment, and fluctuated continuously in semi-closed environment.(2)Through the initial screening, separation, purification, recovery, an efficient phenanthrene-degrading bacteria was obtained from the river bottom sediment in the suburbs of Xuzhou City, Jiangsu Province. After culture observation, Gram stain, 16 S r DNA strain identification and so on, it is confirmed that this strain belongs to the Microbacterium, and has 97% homology with Microbacterium sp. Atl-19. The degradation rate of phenanthrene was 46.97% in 15 days(3)The temperature effects on degradation of phenanthrene efficiency significantly. At 30 ℃, the degradation rate of phenanthrene was the highest, and the degradation rate was 52.85% in 28 days. When p H is 7~ 8, the efficiency of phenanthrene degradation is high, the rate of degradation can reach 53.94%. The initial concentration of phenanthrene was correlated with the degradation efficiency negatively. The lower the initial concentration of phenanthrene was, the higher the degradation efficiency. The biodegradation rate of phenanthrene was significantly improved by adding Tween-80, which increased by nearly 20%. The degradation degradation effect of phenanthrene was best under open conditions. The degradation rate of phenanthrene was decreased during the 28 days in open, closed and semi closure levels. In addition, products of phenanthrene degradation were 1-Naphthol-2-carboxylic acid and catechol.(4)In addition, the biodegradation of phenanthrene in different environments was in accord with the first order kinetic model. The temperature, p H value, initial phenanthrene concentration and different closure levels had significant influence on the biodegradation process. When the concentration of Tween-80 was more than 0.1%, the Tween-80 concentration had no significant effect on the biodegradation efficiency. |
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