Screening Of Nitrobenzene-degrading Strains Under Low-temperature And Its Experimental Research About Remediation In Simulated Groundwater

The purpose of this thesis is to resolve the problem of nitrobenzene pollution under low temperature in groundwater, two group of mixed strains, A and B are isolated and domesticated, they can degrade nitrobenzene efficiently and are also adapted to the low temperature in groundwater. At the same time, the research on strain appearance, degradation condition and degradation dynamics are also carried on.Five single germs are separated from the A, B. a₁, a₂, b₁, b₂, b₃. a₁ and b₂ are gram-positive bacteria. a₂, b₁ and b₃ are gram-negative bacteria. a₁,a₂ and b₂ are bacilli, b₁ is cocci, b₃ is short bacilli. The highest degradation efficient strain is b₂, the Biolog appraisal result of B2 is Bacillus cereus.In the simulating experiment of bioreactor barrier, there is little impact to the result of the sand sample used in the experiment and the native microorganism in the sand, which can be ignored. The experiment can be classified into three stages. The first stage(0～10d),because of the low concentration of nitrobenzene in influent, nitrobenzene can be degraded completely. The second stage(11～22d), because of rising of nitrobenzene concentration, the degradation efficient is between 80%～90%. The third stage(23～76d), because the bacterium in the reaction barrier has adapted to the concentration fluctuation, the degradation efficient become steady, which is between 90%～94%. The result of the experiment proves that the bioreactor barrier is an effective means to treat the polluted groundwater by nitrobenzene.