Anodizing Plants Wastewater Treatment With Application Of The Gacs Method Of Zeologic S.A.


General Information
Wastewater occurring from metalworking industries is defined from the kind of procedures that are implemented to the metallic materials. Anodizing is an electrochemical procedure targeting at the procession the aluminum surface. The aim of this procedure is the production of an oxide layer in its surface, which improves its durability and appearance. Processes in anodizing plants involve usually the following four basic stages:
  • Pre-processing of aluminum,
  • Anodizing,
  • Coloring (if needed)
  • Sealing.
Anodizing is difficult to compare with any other aluminum surface process, because of the fact that metallic products this process, acquire a noteworthy durability, and apart from their metallic appearance, are rendered ideal for use in a burdened environment (e.g. an environment with high pollutant concentrations, coastal areas etc). The environmentally apt treatment and disposal of wastewater produced from anodizing plants constitutes a hard challenge for the metal industries, since the implemented techniques for such type of waste, have granted questionable results. Another significant matter of such techniques, as well is the disposal of the sludge produced as a treatment byproduct, which has to be stabilized and inactivated before the generated byproduct can be disposed safely to the environment as an inert material.
The GACS Solution (Geochemical Active Clay Sediment)
The Geochemical Method GACS consists an innovative solution on an international level on the subject of treatment and disposal of wastewater produced from anodizing plants among others. The key characteristic of the Geochemical Method GACS is the usage of geopolymer materials, which have the ability to adapt on the characteristics and particularity of any type of waste, thus ensuring a successful treatment with warranty of optimal performance.
Benefits of the GACS Method, on treatment of anodizing plants wastewater against the conventional existing methods can be summarized in the following:
Financial Benefits:
  • Competitive investment cost
  • Significantly reduced operational cost
  • Significantly reduced maintenance cost
  • Reduced sludge production
  • Reduced operational time

Environmental Benefits:
  • Heavy metals removal even on high concentrations
  • Sulfates removal
  • Effluent complying with legislation
  • Production of inert sludge
  • Use of natural materials
  • Recovery / reuse of treated water in the production line (Zero Discharge)
Results of an indicative chemical analysis on a wide range of significant parameters on samples derived from anodizing plants prior and following the utilization of the GACS Method are presented in the table below:
Chemical Parameter Anodizing Plants Wastewater
Initial Measurement Final Measurement Pollutant Load Removal
Ph (Units) 3,4 6,9 Neutral
COD (mg/lit) 318 15 95,3%
NO4 (mg/lit) 944 27,5 97,1%
SO4 (mg/lit) 14540 560 96,1%
PO4 (mg /lit) 0 0 -
Fe (mg/lit) 25,7 0,11 99,6%
Cr (mg/lit) 1,37 0,011 99,2%
Ni (mg/lit) 8,13 0,13 98,4%
SS (mg/lit) 245 5 98%
Al (mg/lit) 2400 0,5 99,9%
Zn (mg/lit) 0,09 0 100%
Pb (mg/lit) 0 0 -
F (mg/lit) 0 0 -