Physico-chemical treatment of waste water contaminated with heavy metals in the industry of metallic coatings

• Main Authors: Valencia Jacipt A.R., González Jordi P., Jimenez-Pitre Iris, Molina-Bolívar Geomar
• Format: Article
• Language: English
• Published: Sciendo 2019-12-01
• Series: Journal of Water and Land Development
• Subjects: coagulation-flocculation; heavy metals; industrial waste water; metallic coatings; precipitation
• Online Access: http://www.degruyter.com/view/j/jwld.2019.43.issue-1/jwld-2019-0075/jwld-2019-0075.xml?format=INT

This investigation was undertaken to determine the optimum conditions for physical-chemical treatment of waste water contaminated with heavy metals in the industry of metallic coatings. The industry uses substances such as: inorganic acids, alkalis, acidic and alkaline metal salts, that has a high water demand in the processes of flushing and cleaning the parts to be coated. According to the preliminary characterization of samples and reported in the literature theory, physico-chemical process was implemented for the removal of contaminants that consisted in chemical oxidation of CN-ions, followed by chemical precipitation made next to a coagulation/flocculation and subsequent adsorption on activated coal. Laboratory scale tests showed the optimal conditions of treatment including chemical oxidation by the addition of 4.15 cm3 of H2O2 (30%) per gram of CN, chemical precipitation with NaOH to a pH of 12, followed by coagulation/flocculation with Fe2(SO4)3 at a speed of 135 rpm for 3 min and 20 rpm for 20 min and finally the addition of 1.0 g of adsorbent previously activated at 700°C. From this study, it is clear that the adsorption on activated carbon is highly efficient in the removal of heavy metals from industrial waste water from electroplating. However, it is also clear that the parallel application of the treatments, shown here, is more effective to completely remove contaminants such as lead, nickel, silver, and copper at laboratory scale, so it is recommended the simultaneous use of these physico-chemical processes.