ECOLOGICAL ASSESSMENT OF WASTEWATER FROM THE DEGREASING STAGE IN THE LEATHER INDUSTRY

Abstract

The article examines the ecological condition of wastewater generated at the leather degreasing stage. Three types of degreasing compositions were selected as the research objects: kerosene + surfactant (SFM), a surfactant composition without organic solvent, and a gasoline + surfactant (SFM) working solution based on a by-product. The results were analyzed in tables and graphs, and the ecological risk of the wastewater was assessed by comparing them with regulatory values. It was found that in the kerosene+SFM and especially in the SFM composition variants, the chemical oxygen demand (COD), nutrient content and non-natural substances significantly exceed the permissible limits, which leads to an increase in reagent consumption at treatment facilities and intensifies ecological risk. In the gasoline+SFM variant, the degreasing efficiency is satisfactory, while COD and nutrient concentrations are comparatively lower and closer to the standard values, and non-natural substances remain within the normative range. Therefore, the gasoline+SFM composition is recommended as the most balanced option from both technological and ecological viewpoints for the degreasing process.