title: A built-in zero valent iron anaerobic reactor to enhance treatment of azo dye wastewater.
abstract: Waste scrap iron was packed into an upflow anaerobic sludge blanket (UASB) reactor to form a zero valent iron (ZVI) - UASB reactor system for treatment of azo dye wastewater. The ZVI acted as a reductant to decrease ORP in the reactor by more than 40 mv and functioned as an acid buffer to increase the pH in the reactor from 5.44 to 6.29, both of which improved the performance of the anaerobic reactor. As a result, the removal of color and COD in this reactor was 91.7% and 53%, respectively, which was significantly higher than that of a reference UASB reactor without ZVI. The UV-visible spectrum demonstrated that absorption bands of the azo dye from the ZVI-UASB reactor were substantially reduced. The ZVI promoted methanogenesis, which was confirmed by an increase in CH(4) content in the biogas from 47.9% to 64.8%. The ZVI bed was protected well from rusting, which allowed it to function stably. The effluent could be further purified only by pH adjustment because the Fe(2+) released from ZVI served as a flocculent.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, Department of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China. zhangyb@dlut.edu.cn
authors.forename: Yaobin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yanwen
authors.initials: Y
authors.lastname: Jing
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Liu
authors.forename: Pascal
authors.initials: P
authors.lastname: Onu
mesh_terms: D000693:Anaerobiosis; D001391:Azo Compounds / Q000302:isolation & purification* / Q000378:metabolism*; D019149:Bioreactors; D003116:Color; D004396:Coloring Agents / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D010100:Oxygen / Q000302:isolation & purification / Q000378:metabolism; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D012722:Sewage; D014874:Water Pollutants, Chemical; D007501:Iron; D010100:Oxygen