title: Bioaugmentation with a pyridine-degrading bacterium in a membrane bioreactor treating pharmaceutical wastewater.
abstract: The bacterial strain Paracoccus denitrificans W12, which could utilize pyridine as its sole source of carbon and nitrogen, was added into a membrane bioreactor (MBR) to enhance the treatment of a pharmaceutical wastewater. The treatment efficiencies investigated showed that the removal of chemical oxygen demand, total nitrogen, and total phosphorus were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of pyridine was obtained in the bioaugmented reactor. When the hydraulic retention time was 60 hr and the influent concentration of pyridine was 250-500 mg/L, the mean effluent concentration of pyridine without adding W12 was 57.2 mg/L, while the pyridine was degraded to an average of 10.2 mg/L with addition of W12. The bacterial community structure of activated sludge during the bioaugmented treatment was analyzed using polymerase chain reaction -denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the W12 inoculum reversed the decline of microbial community diversity, however, the similarity between bacterial community structure of the original sludge and that of the sludge after bioaugmentation decreased steadily during the wastewater treatment. Sequencing of the DNA recovered from DGGE gel indicated that Flavobacteriaceae sp., Sphingobium sp., Comamonas sp., and Hyphomicrobium sp. were the dominant organisms in time sequence in the bacterial community in the bioaugmented MBR. This implied that the bioaugmentation was affected by the adjustment of whole bacterial community structure in the inhospitable environment, rather than being due solely to the degradation performance of the bacterium added.
authors.affiliation: College of Environmental Sciences and Engineering, the Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University Beijing 100871, China. dhwen@pku.edu.cn
authors.forename: Donghui
authors.initials: D
authors.lastname: Wen
authors.affiliation: College of Environmental Sciences and Engineering, the Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University Beijing 100871, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China
authors.forename: Ruilin
authors.initials: R
authors.lastname: Xiong
authors.affiliation: Zhejiang Provincial Key Laboratory of Water Science and Technology, Department of Environmental Technology and Ecology, Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314050, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China
authors.forename: Lujun
authors.initials: L
authors.lastname: Chen
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D004345:Drug Industry; D007220:Industrial Waste; D008567:Membranes, Artificial; D010231:Paracoccus denitrificans / Q000378:metabolism*; D011725:Pyridines / Q000378:metabolism*; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D007220:Industrial Waste; D008567:Membranes, Artificial; D011725:Pyridines