For Deceuninck, a global producer of PVC window and door systems, Trevi designed and implemented a wastewater treatment installation to ensure compliance with discharge limits for lead and zinc.
Challenge
Deceuninck offers a wide range of sustainable extruded plastic window and door systems and other building products. The company is specialised in compounding, mould construction, design, development, extrusion, finishing, recycling and injection moulding of plastic window systems, profiles and seals, as well as wood composite applications for the construction industry.
The profiles leaving the extrusion machines are cooled via a secondary cooling water circuit. The customer engaged Trevi to design a treatment installation for the removal of lead and zinc, in order to comply with discharge conditions.
Solution
The wastewater from the secondary cooling circuit is stored in a buffer tank. Through limited acid dosing, an optimal pH is achieved. A sand filter prevents suspended solids from blocking the resins. The ion exchange system consists of two columns, each filled with a selective weak acid resin. Lead and zinc ions are exchanged for sodium ions.
In addition to reducing the lead and zinc concentrations to well below the discharge limits, other discharge parameters are also positively influenced.
The two columns are installed in series. When the first column becomes saturated, it can be replaced without stopping the process and subsequently be put back into operation as the final polishing step.
On average, one filter column needs to be provided with new resin annually.
Result
Trevi first carried out an initial laboratory test to verify the feasibility of selective ion exchange. This was followed by an extensive pilot test to design the optimal process configuration and installation layout.
The final installation ensures stable compliance with discharge standards for lead and zinc, while allowing continuous operation without process interruption.
