Simple Processing Method for Wastewater of Plating Factory Containing High Concentration of Hexavalent Chromium

<p>The processing of wastewater containing high concentrations of hexavalent chromium, commonly used as a powerful oxidant in many industrial production processes, is not readily available in developing countries. Previously, to develop a simple treatment method for wastewater containing high concentrations of hexavalent chromium, we have been investigated the processing of the artificial wastewater using inexpensive inorganic compounds as treatment agents. As a result, it was confirmed that hexavalent chromium ions were specifically removed as the precipitate containing iron chromate complex and iron chromate from the artificial wastewater by adding ferrous chloride after adding calcium hydroxide. In the present study, to evaluate the practicality of this precipitation treatment method, we verified the processing effect of the aged plating wastewater supplied from a metal plating plant complexly contaminated with high concentrations of hexavalent chromium and several heavy metal ions. As a result, hexavalent chromium, zinc, copper and lead ions in the aged plating wastewater were effectively precipitated and removed by this precipitation method regardless of the presence or absence of agglomeration treatment. Furthermore, no significant re-eluting of hexavalent chromium, zinc, copper and lead ions from the fine powders of the precipitates at pH 3-11 was observed on the re-eluting experiments.</p>