Study On Degradation Of Substituted Anilines By Domesticated Complex Bacteria In The Natural Water

Activated sludge sample was colletced from the secondary settling tank in the Sewage Treatment Plant of China petrochemical corporation Nanjing chemical industry Plant. The complex bacteria were abtained by domesticating 4-chloroaniline using the selectivity culture method. Microbial community of complex bacteria was identified by plate culture observation techniques and Gram stain method. The complex bacterias were Kurthia, Ochrobaltrum, Xanthomonas and Brevibacterium. One kind of mycete was included, which was Fusarium sp.Bacterial growth inhibition test was used to determine the acute toxicity of substituted anilines to domesticated complex bacteria and mixture bacteria in natural waters (Qinghuai River). The result was that domesticated complex bacteria's tolerance to compounds studied was stronger than the mixture bacteria in natural waters. It can be found tnat the acute toxicity of substituted anilines to the complex bacteria had obvious correlation with that of mixture bacteria in the natural water, when excluding 4-chloroaniline used for domestication, the R~2 is 0．9．Using domesticated complex bacteria as an inoculum, the biodegradability of substituted anilines was determined by shaking-flask test. The results showed that the biodegradation rates of the complex bacteria to compounds have been obviously improved after domesticating. Based on the final removal rates, the substituted anilines was arranged as this order: 4-chloroaniline (97．0%)>4-bromoaniline (91．5%)>3-chloroan iline(88．0%)>2-chloroaniline(64．9%)>2,4-dichloroaniline(58．4%)>2,4,6-trichloroaniline( 47．1%). It was found that the mixture bacterias in natural waters has a weak degrability to the pollutants in the river, the biodegradation rate of the bacteria was very low with a long lag period. It was not easy to remove the pollutants effectively and quickly only by the mixture bacteria in waters. The complex bacteria's degradability changed with adding the mixture bacteria. It has been shown that there is competition or synergism between complex bacteria and river bacteria.The biodegradability of two coexistent substituted anilines, such as 4-chloroaniline and 2-chloroaniline, 4-chloroaniline and 4-bromoaniline, and 2,4-dichloroaniline and 2,4,6-trichloroaniline were studied. We could found that the final removal rates of 2-chloroaniline (66．7%) was higher when coexisting with 4-chloroaniline comparing with single one's (64．9%). It means the enzyme generated from metabolizing 4-chloroaniline improved the biodegradation to 2-chloroaniline. When coexistng with 4-chloroaniline, the biodegradabihty of 4-bromoaniline (81．3%) was not as good as the single one's (91．5%). The biodegradability of coexistant 2,4-dichloroaniline and 2,4,6-trichloroaniline was lower, there were 52．9% and 35．8%.