Integrated electrodialysis/electro-oxidation process for the treatment of chlorpyrifos wastewater with high energy efficiency.

A novel integration of the electrochemical process with electrodialysis and electro-oxidation (IEDEO) was designed for the effective pretreatment of chlorpyrifos manufacturing wastewater, with high concentrations of both salts and organic compounds. The effects of operating parameters including initial pH and constant voltage on the IEDEO process performance were investigated. The IEDEO process showed excellent performance for the simultaneous removal of bio-refractory organics and inorganics in the chlorpyrifos wastewater. In contrast with the single EO process, the results of energy consumption, UV-vis spectra, and GC-MS showed that the oxidation performance for chlorpyrifos wastewater by IEDEO was carried out more efficiently. The biodegradability of the chlorpyrifos wastewater pretreated by IEDEO was significantly improved. The total salt removal (90.3 ± 2.1%) from the chlorpyrifos wastewater obtained by IEDEO was significantly higher than the 5.8 ± 1.6% removal attained with the EO process. The COD removal of chlorpyrifos wastewater by the IEDEO process was 25.5 ± 1.2%, and the energy consumption of the IEDEO process was 15.1 ± 1.6 kWh kg COD at 2 h, representing a 60-65% reduction compared to the EO process. This indicated that the IEDEO process was a valuable pretreatment technique for biological treatment. Moreover, scanning electron microscopy and X-ray diffraction results demonstrated that the IEDEO concentrate was beneficial for subsequent evaporative desalination.