A built-in zero valent iron anaerobic reactor to enhance treatment of azo dye wastewater

摘要

Waste scrap iron was packed into an upflow anaerobic sludge blanket (UASB) reactor to form anzero valent iron (ZVI) - UASB reactor system for treatment of azo dye wastewater. The ZVI actednas a reductant to decrease ORP in the reactor by more than 40 mv and functioned as an acidnbuffer to increase the pH in the reactor from 5.44 to 6.29, both of which improved thenperformance of the anaerobic reactor. As a result, the removal of color and COD in this reactornwas 91.7% and 53%, respectively, which was significantly higher than that of a reference UASBnreactor without ZVI. The UV-visible spectrum demonstrated that absorption bands of the azo dyenfrom the ZVI-UASB reactor were substantially reduced. The ZVI promoted methanogenesis, whichnwas confirmed by an increase in CH4 content in the biogas from 47.9% to 64.8%. The ZVI bed wasnprotected well from rusting, which allowed it to function stably. The effluent could be furthernpurified only by pH adjustment because the Fe2þ released from ZVI served as a flocculent.