Process Water Treatment in Plastic Recycling
Sector Overview
Contents
Sources and Characteristics of Process Water in Plastic Recycling
Process water is the general term for water that is produced during industrial applications. In plastic recycling, process water is part of the cleaning processes and is responsible for conveyance and washing the recycled material. This happens in settling tanks and float tanks. In plastics processing plants, there are different water cycles with different degrees of contamination. This depends on the input material and its composition, such as PET, HDPE, PP, PE, post-consumer or post-industrial.
At the beginning of the process, usually after shredding, coarse impurities are washed out of the plastic. This is followed by a sorting processes and further washing steps, which require increasingly higher water quality. It is crucial that no impurities, organic contaminants, or colour particles enter the next process step in the washing line.
The quality of the process water depends on its area of application. It should be noted that the highest quality of process water is required for transparent food packaging or films. Knowing the composition of your wastewater is crucial for the accurate planning of your process water treatment system. That’s why we work closely with each customer – from the initial idea, through analyses at our in-house laboratory, to the finished plant concept. This way, we can ensure that the plant works efficiently, and we give our customers a full process guarantee. The table below gives an example of the characteristics of process water from a plastic recycling plant.
| No | Parameter | Process water from hot washing systems | Process water from transport lines |
|---|---|---|---|
| 1 | COD (mg/l) | 14 000 – 15 000 | 3 000 – 5 000 |
| 2 | BOD₅ (mg/l) | 9 000 – 12 000 | 3 000 – 4 000 |
| 3 | TSS (mg/l) | 6 000 – 8 000 | 600 – 800 |
| 4 | pH | 13 – 14 | 10 – 12 |
| 5 | Temperature (°C) | 90 | 20 – 25 |
| 6 | Wastewater flow (m³/h) | 15 | 25 |
Read More: Sources and Characteristics of Wash Water in Plastic Recycling
Process Water Treatment & Disposal in Plastic Recycling
Plastic recycling facilities generate process water contaminated with chemicals, oils, fine plastic particles, heavy metals, and organic residues from washing and shredding processes. Effective treatment and disposal are essential to meet environmental regulations and minimize operational costs.
Process Water Disposal Options
1. Water Reuse & Recycling
Closed-loop Water Systems: Treated water is reused in washing and cooling processes, reducing water consumption.
2. Sewer Discharge
Municipal Wastewater Treatment: Requires compliance with local pretreatment standards for pH, BOD, COD, and suspended solids.
Process Water Treatment Methods for Plastic Recycling
1. Physical Treatment
Screening & Sedimentation: Removes large plastic particles and solids.
Filtration: Sand or multimedia filters remove suspended solids.
Oil-Water Separation: Removes oils, adhesives, and other floating contaminants.
2. Chemical Treatment
Coagulation & Flocculation: Adds coagulants (e.g., aluminum sulfate, ferric chloride) to remove microplastics and suspended solids.
pH Adjustment: Neutralizes acidic or alkaline wastewater.
Oxidation: Uses chlorine or ozone to break down organic contaminants.
3. Biological Treatment (If Needed)
Activated Sludge Process: Degrades organic residues from labels, glues, and organic contaminants.
4. Advanced Treatment
Electrocoagulation: Uses electric current to remove fine plastic particles and heavy metals.
By implementing these technologies for plastic washing lines, we can completely remove COD, BOD5, TSS, oil as well as colour particles and dyes from the de-inking process water. Likewise, ClearFox® technologies treat substances dissolved in the water, including hard to remove, persistent substances thus allowing process water to be run in a closed loop without cross contamination. At the customer’s request, we can also clean the process water to a standard suitable for discharge into the sewer system or a receiving water body.
Design and purchase of a process water treatment plant
Once you know the composition and the correct treatment methods for your process water, the next step is the detailed design of the wash water treatment plant. We support you in every area so that you receive a comprehensive concept. With us as your partner, we guarantee you a highly effective plastic recycling wash water treatment solution and the best service from a single source. That is why we are the European market leader in developing and manufacturing plastic wastewater and process water cleaning and reuse systems.
Small footprint
Automatic operation with remote monitoring
Lowest operating costs on the market
Fast commissioning through plug & play concept
Solutions adapted to your site specifications
Complete service
Global capability
Since the company was founded, we have focused on the treatment of industrial process water worldwide. Through research and the development of new technologies, we can treat more complex process waters with difficult pollutants. We have combined the ClearFox® DAF and the biological FBBR treatment processes with advanced electrical oxidation technology and ultrafiltration. In this
We construct our plants so, that they integrate seamlessly with existing washing lines. Your process water does not have to travel long distances for treatment, so you can feed it back into the cycle immediately. We attach great importance to a compact footprint for our systems. No matter what form of plastic you recycle, through a precise analysis of your wastewater and an overview of your process steps, we always offer you the most efficient solution.
We involve our partners and clients in every planning step of the process water treatment plant. After purchase, we not only ensure speedy installation and commissioning, we also train your responsible staff to ensure smooth operation of your plant. Our team is at your service worldwide. Using modern remote monitoring, we can optimise and monitor your system in real time.
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• Key design questions
• Common mistakes to avoid
• Factors that influence pricing
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