Study On Filtration And Characteristic Of Aerobic Microbial Community Degrading Hexachlorobenzene

Hexachlorobenzene (HCB) is one of the typical Persistent Organic Pollutants (POPs), which can lead to serious hazards to human health and environment.Objective: As the reason of the bioaccumulation, persistence as well as potential toxicity, there is no economic, effective and widely applicable treatment of HCB at present. Biodegradable experiment has held to investigate the biodegradability of HCB.Method: An aerobic microbial community which was able to grow at the presence of hexachlorobenzene was enriched from sediment from contaminated site. Fermenter was use to magnifying culture microbial community and based on immobilized microorganism technique, fermenter would be simulated as strengthening SBR system to treat the actual wastewater with HCB.Results: (1) Isolation of aerobic microorganisms degrading HCB. Two strains of microorganisms which were able to grow at the presence of HCB were isolated from the sludge collected from the drain of a chemical plant in Wuhan. The strains showed the capability of degrading HCB efficiently, and they were identified as Alcaligenes sp. and Azospirillum sp.. During the growth of the mixed microorganisms on HCB, the cumulative consumption oxygen amount was detected higher than their endogenous respiration. Under the condition of temperature 30℃, pH 7.0 and the concentration of HCB is 4.5mg/L , the HCB decomposition rate of these bacterial reached 137.5μg·(L·d)-1.(2) Culture of aerobic microbial community degrading HCB. Inoculated microorganisms to fermentation tank, after expanded incubating, they still have the biodegradability of HCB, and the degradation rate was more than 35%.(3) Degradation of Wastewater by aerobic microorganisms. Immobilized microorganisms were used to enhance SBR system to treat the wastewater with HCB. The results show that the removal of HCB was efficient by adding the aerobic microorganisms, and also an improvement on the acute toxicity of original wastewater to tetrahymena pyriformis, but COD, ammonia removal was less affected. Conclusion: The results showed that the aerobic microbial community was able to utilize HCB as sole carbon and energy source, and the degradation of HCB was efficient. They still have the biodegradability of HCB even after magnifying cultured, and immobilized microorganisms could improve the traditional biologic treatment to remove HCB.