USING OXIDIZING METHODS TO TREAT SULFIDE-ALKALI WASTEWATER
We studied the process of treating sulfide-alkali wastewater to eliminate soluble hydrocarbons, the wastewater having previously passed successively to the stage of removing floating components, volatile organic compounds, and sulfides using the methods of sedimentation, distillation and precipitation with an Ni<sup>2+</sup>-containing spent electroplating solution. Oxidizing method was used as the method of eliminating soluble hydrocarbons, involving various oxidizers, such as hydrogen peroxide and ozone-air mixture with and without adding the Ni<sup>2+</sup> ions in the amount of 172 mg/l, contained in the spent electroplating solution. It is shown that using as oxidizer the 3-% hydrogen peroxide and ozone-air mixture (with the ozone concentration of 3 mg/l) leads to achieving 17.0 % of the wastewater purification index by the chemical oxygen demand (COD) value. It is found that the Ni<sup>2+</sup> ions contained in the spent electroplating solution provide a catalytic effect on the process of oxidizing the components of sulfide-alkali wastewater with ozone-air mixture. It is found that the highest wastewater purification index by the COD value, 56.0 %, is reached resulting from oxidizing the hydrocarbons with ozone-air mixture using the Ni<sup>2+</sup> ions, which is 39.0 % higher as compared with non-catalytic oxidation in similar process conditions. Thus, we have demonstrated the applicability of the Ni<sup>2+</sup>-containing spent electroplating solution as a catalyst of oxidizing the wastewater sulfide-alkali pollutants with ozone-air mixture.