LAUSR

Synthetic and real wastewater, containing nickel (Ni) and hexavalent chromium (Cr(VI)), have been treated using electrocoagulation, under various operating conditions. The treatment process of electrocoagulation was performed using copper electrodes. The following parameters were examined to study their effects upon the treatment process: initial pH values, current densities, electrolysis times, the spacing between electrodes, modes of operation (batch vs. continuous), and electrolyte types. The results showed that the best removal efficiencies for Ni and Cr(VI) were obtained at pH = 9.2; current density = 5–10 mA/cm2; and an electrode spacing of 4 cm, using NaCl as the electrolyte. Ni and Cr removal efficiencies reached 99.96% and 98%, respectively. Batch and continuous modes of operation achieved almost the same removal efficiency, while the batch mode consumed more electrical energy. Compared with electrocoagulation, chemical coagulation using copper salts demonstrated lower removal efficiencies for both Ni and Cr. Scanning electron microscopy was used to assess the morphology of the electrodes. The electrical energy cost varied from 0.8–3 US$/m3, while the material cost totaled around 0.003 US$/m3.