Study On Degradation Of Chlorophenol By Dominant Mixed Bacteria

Dominant mixed bacteria which was able to utilize chlorophenol as sole carbon source and energy source was isolated, incubated and domesticated from the sludge collected from the returned sludge well hole in the Yangzi Petrochemical Company's industrial wastewater treatment plant. By identification, dominant mixed bacteria included five kinds of bacteria, which were Flavobacterium Acinetobacter, Alcaligenes Mycopiana Pseudomonas.It was proved by bacteria growth-inhibition experiment that the isolated mixed bacteria's toleration to chlorophenol was better than the bacteria from nature water (Yangtze River) , and after the domestication with 2-chlorophenol selective medium, dominant mixed bacteria's toleration was improved evidently.We used domesticated mixed bacteria as degradation microorganism, and adopted laboratory simulation method to research their biodegradation characteristic to three kinds of chlorophenol. The result proved that three kinds of mono-chlorphenol were isomers, but different chlorine sub-position could bring major influence to the chlorophenolic biodegradability;the order in which chlorophenols were readily degraded was: 3-chlorophenol>2-chlorophenol>4-chlorophenol.Using 3-chlorophenol as object pollutant, we researched the effects to object compound's biodegraded velocity and ultimate degreased rate by some condition factors, such as the exposure concentration of compound, the mixed bacteria's inoculum size, the water's pH value and so on. The result proved that the mixed bacteria had greatly strong flexibility to environment's change, and could adopt the abroad pH value's scope from 3.5 to 9.5. Depressing the water contaminant's concentration and improving the mixed bacteria's inoculum size could improve the object compound's biodegraded velocity.It had primary influence to the chlorophenolic biodegraded characteristic for adding in easily degraded growth matrix. It was in favor of microorganism degrading 3-chlorophenol by adding in phenol. Generally speaking, phenol will be degraded firstly, then 3-chlorophenol will be decompounded, and its metabolic efficiency will be improved. At the same time, 3-chlorophenol's degraded efficiency will be improved as the phenolic concentration'sincreasing.Compared with existence lonely, when 2-chlorophenol and 3-chlorophenol co-existing, their lag phase and the time to reach degradation balance all appeared obvious hysteresis, their half life had obvious prolong, and their ultimately wipe-off rate all had a little reduction. It was obvious that two chlorophenolic coexisting could bring inhibitory action to the degradation of mixed bacteria, and their combined action was additive effect.By researching the biodegradation dynamics of chlorophenols, it showed that 3-chlorophenol 's biodegradation could bring two kinds of mostly intermediate product, and metabolic product had evident process that it was degraded after accumulation. We presumed that 3-chlorophenol's metabolic pathway was: it occurred adjacent position's oxygenation in the effect of odd-oxidase, and then produced chlor-catechol. After this process, chlor-catechol occurred adjacent position's ring opening in the effect of 1, 2-dioxygenase;then released chloride ion in the course of internal esterification, and was oxygenated to be maleoyl scetic acid;at last, it came in tricarboxylic acid cycle.