| For the malodorous gas of the oil waste-water, denitrification was used to remove the malodorous gas of oil wastewater in this experiment.The volatile organic compounds were detected by SPME-GC/MS. The change of the volatile organic compounds was studied and the mechanism of the removal of malodorous gas in oil wastewater by denitrification was analyzed. Under the stable condition, the microbial communities in different stages of activated sludge samples were analyzed by high throughput sequencing technology.The dominant bacteria in different systems were identified and the changes of microbial community structure were analyzed.The results show that:(1) The stench of oil wastewater are composed of small molecular aldehydes, ketones and carboxylic acids, alcohols and other oxides, peroxides. Under anoxic conditions, denitrifying bacterium used NO3--N as the electron acceptor, the volatile organic compounds as the electron donor, and the malodorous gas of the oil wastewater was disappeared. The emission of the oil wastewater’s VOC was about 245ug/L, when the treated water was about 1.3ug/L, and it was decreased over 99.5%. The odor intensity of oil wastewater decreased gradually with the reaction, the raw wastewater has strong rancidity, as the reaction proceeds, odor intensity was finally reduced to the weak level.(2) The optimum C/N was 5.2. Under this condition, malodorous gas was disappeared, compared with the inflow the emission of the treated water’s VOC was decreased over 99.5%, the removal rate of COD was over 90%, and there was no NO3--N remained, avoid the apothecary waste and secondary pollution.(3) After denitrification treatment, the number of volatile organic compounds in the oil wastewater was reduced, the number was decreased by 55, and the concentration was also decreased, the peak area was decreased by 66.76%. Before treatment, the main component of the oil-wastewater were ketones, alcohols, aldehydes, acids and aromatic ethers, when the effluent was ketones. Most of the volatile organic compounds in the oil wastewater were removed, the amount and concentration of volatile organic compounds were decreased, and the change of these substances made the odor of oil wastewater disappeared.(4) The activated sludge was domesticated under the constant condition, the removal effect of the system was gradually improved with the domestication, and finally tends to be stable. Microbial community had obvious succession with the extension of the domestication, the diversity of microorganism, the richness of species composition and the degree of evenness were all decreased. Inoculated sludge were collected from sewage treatment plant, were rich in microbial community. With the domestication of the activated sludge, the microbial flora survival of the fittest. Finally only the adapted microbial flora were remained.In the whole process of domestication, proteobacteria was the optimal flora, and the proportion has increased. Candidate_division_OD1 become the second dominant flora after 30 days.Actinobacteria, Gemmatimonadetes,Chloroflexi, Acidobacteria, Nitrospirae, Planctomycetes, Cyanobacteria were disappeared, and Verrucomicrobia, Firmicutes were appeared. Simplicispira, Candidate_division_OD1, Comamonadaceae, Hydrogenophaga, Thauera、increased during the domestication process, they were the important bacteria in the microbial community of the system removal of odor substances from oil wastewater by denitrification.This paper provides a technology for removing oil wastewater’s malodorous gas, it protects the atmosphere and has low energy consumption. It has wide application, and significant economic and environmental benefits. |
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