Sulphate and Fluoride Abatement Technologies for Restrictive Limits Zero Discharge Purification: When and Why

Date: 03/06/2021
Author: Sponsored

CIE, with 40 years of experience, is one of the leading companies in Europe in the design, development, production and installation of standard wastewater systems and Zero Liquid Discharge systems for metal finishing lines, enabling the transformation of wastewater into a precious resource for a total reuse of water.

  • The increasingly frequent local restrictions of the European law on discharges for Sulphates and Fluorides (and often Aluminium) require cutting-edge systems and specialty chemicals which nowadays are already consolidated. In addition, the Sulphates problem directly affects Anodic Oxidation. Here, besides the adoption of acid recovery equipment (OXIPUR), the chemistry is taking on a decisive role.
  • The Zero Liquid Discharge (Z.L.D.) in the Aluminium sector is now more than 30 years old, but its use is still limited and amounting to less than 5% of the existing systems. The reasons are mainly economical and lack of incentives (tax relief, water saving bonuses, etc.). However, the path has been traced and the new technologies that lead to a drastic reduction of the final evaporation or even to its elimination with the help of specific chemical products, should lead to overcoming obstacles to its development. The developments of PUR-ALL® in both Coating and Anodic Oxidation field lead to much less expensive and more suitable Zero Discharge solutions for coating lines where water consumption is modest. For Anodic Oxidation, the most convenient solution today is that of the PUR-ALL® process, which allow to obtain a decrease in water consumption and the corresponding respect for very low limits (300 ppm) of Sulphates. The most evident case is that of TALEX (2 Anodic Oxidation lines + 1 Coating line) which has increased from 50 m3/h to 25 m3/h of water consumed and Sulphates <300 ppm.