Influence of output current on decolorization efficiency of azo dye wastewater by a series system with multi-stage reverse electrodialysis reactors

Abstract

A series system with multi-stage reverse electrodialysis reactor (REDR) can harvest salinity gradient energy (SGE) from working fluids as much as possible to treat organic wastewater. In this paper, the series system simulated with a single REDR system to degrade azo dye wastewater was investigated experimentally. The results showed that the series system could not only degrade azo dye wastewater effectively, but also output a certain of electric energy simultaneously. In the series system, the salinity gradient variations of working fluids which flowing through each stage REDR affected only on the output voltage of each stage REDR, but which almost did not affect on the decolorization efficiency of azo dye wastewater of each stage REDR. However, the output current variations of the series system effected significantly on the decolorization efficiency. Although the increase of output current was benefit to the decolorization efficiency for each reactor in the series system, the number of reactors in the series system will reduce quickly, which results in total decolorization rate of azo dye wastewater decrease. When the current was 0.1A, the overall performances of the series system would be relatively optimal under the experimental conditions. The number of reactors, total decolorization rate of azo dye wastewater, utilization efficiencies of SGE and membrane area, and net output power could reach 19, 1.91 mg·s−1, 6.92 mg·J−1, 31.21 mg·m−2s−1 and 0.68 W, respectively.