title: Azo dye removal in a membrane-free up-flow biocatalyzed electrolysis reactor coupled with an aerobic bio-contact oxidation reactor.
abstract: Azo dyes that consist of a large quantity of dye wastewater are toxic and persistent to biodegradation, while they should be removed before being discharged to water body. In this study, Alizarin Yellow R (AYR) as a model azo dye was decolorized in a combined bio-system of membrane-free, continuous up-flow bio-catalyzed electrolysis reactor (UBER) and subsequent aerobic bio-contact oxidation reactor (ABOR). With the supply of external power source 0.5 V in the UBER, AYR decolorization efficiency increased up to 94.8±1.5%. Products formation efficiencies of p-phenylenediamine (PPD) and 5-aminosalicylic acid (5-ASA) were above 90% and 60%, respectively. Electron recovery efficiency based on AYR removal in cathode zone was nearly 100% at HRTs longer than 6 h. Relatively high concentration of AYR accumulated at higher AYR loading rates (>780 gm(-3) d(-1)) likely inhibited acetate oxidation of anode-respiring bacteria on the anode, which decreased current density in the UBER; optimal AYR loading rate for the UBER was 680 gm(-3) d(-1) (HRT 2.5 h). The subsequent ABOR further improved effluent quality. Overall the Chroma decreased from 320 times to 80 times in the combined bio-system to meet the textile wastewater discharge standard II in China.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 202 Haihe Road, Harbin 150090, PR China.
authors.forename: Dan
authors.initials: D
authors.lastname: Cui
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Guo
authors.forename: Hao-Yi
authors.initials: HY
authors.lastname: Cheng
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.forename: Fan-Ying
authors.initials: FY
authors.lastname: Kong
authors.forename: Hyung-Sool
authors.initials: HS
authors.lastname: Lee
authors.forename: Ai-Jie
authors.initials: AJ
authors.lastname: Wang
mesh_terms: D000332:Aerobiosis; D001391:Azo Compounds / Q000737:chemistry* / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism; D019149:Bioreactors; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry* / Q000378:metabolism; D004572:Electrolysis; D010084:Oxidation-Reduction; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D014874:Water Pollutants, Chemical; C549930:alizarin yellow R