Aluminium extrusion giant TALEX is located in an area where water is scarce and discharge limits are much more restrictive than the European ones. CIE installed a chemical-physical WWT system powered by PUR-ALL technology. It recovers all acidic waste water coming from the anodising and the pretreatment stages with the ultimate goal of ZLD (recovering of at least 95% of process water).
In the middle of KIZAD (the Khalifa Industrial Zone Abu Dhabi), there is Taweelah Aluminium Extrusion Company LLC (TALEX), the most advanced aluminium extrusion and finishing plant in the Middle East and the 2016 winner of the Gulf Cooperation Council (GCC) award in the category Industrial Project of the Year.
TALEX designs and produces high quality aluminium profiles. TALEX’ production process starts from liquid primary molten metal delivered by EGA to its own cast house converting to precision machined aluminium products in its fully vertically integrated premises. Its plant plot area, covering 200,000 m2, 72,000 of which are covered, and built on a greenfield site in less than five years with a total investment of over 240 million dollars, provides to its prestigious customers casting, extrusion, surface treatment and fabricated aluminium products around the world.
For TALEX, choosing the best available technology has meant to rely on a pool of Italian suppliers to design and equip its extensive surface treatment department with a horizontal powder coating system that integrates a power & free conveyor with a capacity of 1,000 kg (including bars) per rack, and two anodising systems.
CIE (Compagnia Italiana Ecologia) Srl developed an innovative treatment system for the coating and anodising processes’ waste water, which has been implemented in three phases, about two years apart. Today, it enables the company to achieve a closed-loop operation and recover 95% of the water used, a key factor in competitiveness and environmental compliance given the region's water scarcity and the severity of the government's drainage limits.
Waste water treatment: a strategic element for competitiveness and sustainability
Sustainability is an important component of TALEX’ mission, especially considering that this aluminium extrusion giant is located in an area where water is scarce and where the government has imposed much more restrictive discharge limits than the European ones. The technology of CIE Srl (San Zenone al Lambro, Milan) stands out amongst all the other in terms of efficiency and ease of management.
The waste water treatment and recovery system that we supplied to TALEX handles the whole amount of process water of the finishing department. Water is a major issue not only due to its cost and scarcity, but also to the quality standard imposed on discharges in terms of fixed residue (Total Dissolved Solids, TDS). That is why TALEX asked CIE to implement a step-by-step project with the ultimate goal of creating a Zero Liquid Discharge plant, i.e., recovering at least 95% of process water.
The implementation of the ZLD plant needed a 2-phases project
Phase 1 involved the installation of a chemical-physical treatment plant with the PUR-ALL technology, which recovers all acidic waste water, i.e., the process water coming from the anodising and pre-treatment stages, and enables us to reuse it in alkaline rinses, thus achieving a 50% reduction in the water required by the finishing lines.
During Phase 2, the recovery of the process water used on the finishing lines increased to 75% thanks to the installation of special membrane recovery systems, i.e., ultrafiltration and reverse osmosis. The concentrates from the alkaline attack baths of the anodic oxidation process are treated on the existing plants as well, and are not disposed of anymore.
By applying its proven PUR-ALL system, CIE provided a very special water treatment process. CIE has considered the different streams of water separately since the beginning. The waste water is conveyed into a transfer pit area where it is selected depending on its quality. Then, it reaches a large storage area ensuring a flexible production and avoiding any “stresses” even in the water treatment stage, because the quality of water is closely related to the quality of production. From the buffer area, the waste water is sent to the treatment system: the chemical-physical process is sufficient to significantly reduce the content of sulphates, aluminium, and organic residues and reach the quality level needed to feed the alkaline baths. The alkaline stages’ water will be treated by removing any kind of contamination, especially aluminium and COD. The discharged water meets the limits imposed by the local authorities. All machine operations are automatic: the plant features all the BAT for SCADA systems, electronic devices and controls in order to minimise the maintenance times and facilitate the work for operators.
Waste water does not make any profit. Therefore, CIE’s goal is to design plants that require a minimum staff and the minimum possible time for every operation. CIE also supplies the closed-loop production plant of demineralised water used for the anodising and coating lines, while for the sludge treatment we have installed fully automatic filter presses without any operator supervision.