MONITORING THE QUALITY OF GROUNDWATER SAMPLES BEFORE AND AFTER RETROFITTING A CHROME-PLATING PLANT THAT CARRIED OUT THE TRANSITION FROM CR6+ TO CR3+.

Since ancient times, chromium oxide was used 2000 years ago by the Chinese to cover the tips of weapons and later, as late as 1988, hexavalent chromium was discovered to be dangerous to humans. Currently, many companies carry out chrome plating of plastic parts, which consists in creating a superficial layer of diffusion, of an iron-chromium alloy with up to 10 - 20% chromium. Coating by electrolytic deposition is the most widely used method for creating protective layers for plastic materials and consists in electrolysis of aqueous solutions of salts of the respective metal. The paper studies the way in which pollution of underground water is influenced during the retrofitting of the chrome-plating plant by changing raw materials that use Hexavalent Chromium (Cr6+) to Trivalent Chromium (Cr3+). The monitoring period of hexavalent chromium in groundwater included both the period before and after the retrofitting of the factory. This change in the technological process indicates a significant decrease of Cr6+ present in groundwater. Results of the study indicate that retrofitting of the technological process brings a positive effect on environmental pollution because the concentrations of chromium are significantly reduced after changing to trivalent chromium. The paper also highlights the period during which pollutant is absorbed into soil and transported to groundwater. [ABSTRACT FROM AUTHOR]