Biofiltration Of Gaseous Dichlormethane Enhanced By Pandoraea SP

Dichloromethane (DCM), with bioaccumulation, toxicity and carcinogenicity, is a hydrophobic and recalcitrant volatile organic compounds (VOCs), which is widely used in industrial production and existed in the atmosphere of the environment. At present, DCM is considered to be one of the halogenated hydrocarbons which contained bigger toxicity in the atmospheric pollution, industrial waste gas of DCM emission concentrations must below150mg/Nm3, so to explore effective technology has important social and environmental significance.A high-effective strain was obtained in this work. This isolated was assigned to be Pandoraea pnomenusa, was named as LX-1, which was possibly to be a new species able to degrade DCM. The characteristics, kinecitic models and effects of environmental factors on DCM degradation were investigated in the experiment, we also investigated the effects on dechlorination and mineralization, and the possible degradative pathway was proposed based on the above results.The optimal conditions for the growth of strain LX-1were35℃, pH7.0and the NaCl Concentration0%-1%. Strain LX-1can degrade the initial concentration of0-1500mg·L-1DCM, the average mineralization rate and dechlorination rate was74.15%and96.77%, respectively. The growth and biodegradation processes both conformed with Haldane’s kinetics model. The maximum specific growth rate was0.133h"1when the DCM concentration was500mg-L"1. Together with the previous studies, it was concluded that DCM was metabolized to some simpler soluble organic compounds (such as formic acid), which was finally mineralized to CO2, H2O and synthesized to cell biomass.Based on the degradative performance and metabolic characteristic, strain LX-1was employed to bioaugment biofiltration degrading DCM. Biotrickling filter (BTF) and Biofilter (BF) packed with ether-based polyurethane foam and nutrition slow-release media respectively were employed for removing DCM from the waste gases. The biofiltration were inoculated with "strain LX-1+acclimated sludge", the start-up procedures of the BTF and the BF were finished by joint gas-liquid phase inoculation within25d and22d, respectively. Under the conditions of inlet DCM concentrations of100～1500mg·m-3and empty bed residence time (EBRT) of34～85s, both BTF and BF could effectively degrade DCM, and the maximum elimination capacities were22.6g·m-3·h-1and29.05g·m-h·-1respectively. The nutrient pH and salinity had great influence on the biofiltration degrading DCM. The mass ratio of carbon dioxide produced to the DCM removed was approximately linear, and the mineralization rates of DCM in the BTF and BF obtained were70.4%and66.8%, respectively. The results indicated that the DCM was removed mainly via biodegradation. The biofilm of BTF and BF could recover the elimination capacity rapidly in response to shock loads.