One of the methods of detoxification of sulphides in wastewater (WW) of tanneries could be their oxidation by use of MnO₂. This material, as well as the product of the chemical reaction between sulphides and this material is not left in WW and does not pollute it.
The amount of sulphides and the pH of solution have an influence on oxidation process duration; it is longer when the sulphide amount and pH in the WW is higher. Optimal temperature of the treatment is 30°C. Oxidation goes faster if the size of MnO₂ particles does not exceed 0.1 mm.
The possibilities of repeated use of MnO₂ were investigated. The stable efficiency of the MnO₂ could be obtained by putting at first 0.5% of MnO₂ and additionally 0.05% of MnO₂ of the solution mass for every following cycle of the treatment.