Once you have the knowledge regarding the specific pollutants that can be washed from the plastic material that you are going to be recycling, the next step is to consider what specific process water treatment steps you need to use. The core wastewater treatment process is typically standardized for washing line water reuse, however specific add on cleaning modules can be required to deal with specific pollutants depending on the origin and prior use of the plastic being recycled.
Plastic wash water treatment system design
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Cleaning and reuse of plastic recycling wash water
Plastic process water management options
As already previously discussed, the main options for managing plastic recycling process water and wash water are disposal or reuse. When considering disposal, the washing water is often used in a batch process. Here, the wash water is reused until the pollution level becomes too high. At this point the wash water must then be collected and disposed of. This is normally done by tankering of the wastewater offsite. This is a very expensive process and is not considered a sustainable method of handling plastic recycling wash water. Where a recycling facility has a direct connection to a public sewer network, used wash water can often be disposed of in this way.
However, increasing regulations mean that water utilities now charge significant rates and penalties for polluters who put untreated wastewater directly into the municipal sewer system. Where for some reason reuse is not an option, modular solutions can be implemented to remove the pollutants from wash water prior to putting it into the sewer. This can significantly reduce penalties and fines being paid to the water utility.
Reuse of the wash water is the most cost effective and sustainable approach. Increasing costs for clean water and for disposal of polluted water to the sewer makes reuse the best option for any plastic recycling company or machine builder. This is especially relevant in regions with water scarcity. A customized process water reuse system can allow for 98% of the water to be reused and recycled continuously. When considering reuse, it is important to work with a professional company that understands how to integrate there are solutions with your washing line. It is also very important to understand the pollutants in your wastewater and how clean you need the reuse water to be.
Pollutants in plastic wash water
Within the plastic recycling sector, the variation in pollutant types varies significantly. Plastic containers are used to store and hold an unlimited range of chemicals, foods, beverages, pharmaceuticals, etc. Residues of the substances and materials the plastics were used to hold or convey always remained on the plastic. During the washing process these residues enter the wash water and are the main source of pollution.
Because of the wide range of pollutants that can potentially be present in to wash water, the pollution level with regards to key parameters like COD, BOD5 and TSS can typically be extremely high. But the good news is that with our specialist equipment that is customized for the plastic recycling industry, we can effectively clean this wash water to allow reuse.
Pressure release flotation cleaning of wash water
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Our flagship wastewater treatment module for the plastic recycling sector is our specially designed and customized pressure release dissolved air flotation system. This wash water treatment module can be seamlessly integrated into any washing line. It has a very small and compact footprint and can be positioned indoors when used has a skid mounted variant or can be positioned outdoors with the containerized model variant. So regardless of space availability we can offer a solution. Our pressure release flotation system can remove most of the suspended solids, any oils and grease, BOD5 and COD from the wash water.
Standard washing lines that do not require special cleaning standards or pollutants to be removed, our customized pressure release flotation system can allow for complete wash water reuse. The separated and removed pollutants are dewatered, with the separated liquid also being returned to the washing process. This allows us to achieve over 98% water reuse.
We can achieve incredible cleaning efficiencies:
Filtration
With the ever-increasing demands for cleaner wash water, many of our clients are now utilizing a modular ultrafiltration system in combination with our pressure release floatation. This module is designed to integrate seamlessly with a washing line that is already using our flotation system, and it provides an incredible further cleaning efficiency. With an add-on ultrafiltration module, we can remove all particles greater than 0.02 – 0.05 microns.
An example of an application where this level of particle removal can be required is the washing of plastics that are to be reused in the production of plastic films. If large particles are present in the wash water and are not removed, they can end up in the final recycled plastic material.
This cleaning level is generally for sufficient for almost all applications. However, we also have nanofiltration and reverse osmosis modules that can work in conjunction with our washing line pressure release flotation system. So regardless of your requirement we can develop a customized solution that can be integrated with your washing equipment to allow complete reuse full stop.
Specialist treatment steps
Because the potential uses for plastic are unlimited, and the substances plastic are used to hold and convey are also unlimited, any type or mixture of pollutants can potentially be present in wash water. Some pollutants such as suspended solids can be easy to remove.
However, there are many pollutant types that can present challenges to conventional wastewater treatment technologies. Examples of these pollutants are fertilizers and other chemicals. When washing plastic bags and plastic containers there is the possibility passed these pollutants can enter the wash water and accumulate if not removed.
In addition to our pressure release flotation and filtration modules, we also manufacture specialist modules for dealing with other more complex pollutants such as our DiOx module which is an advanced process step for the oxidation of any organic compound. So, while your initial requirement now may only be for a pressure release flotation system to allow wastewater reuse, we have the products, technology and expertise to expand and develop your wash water treatment and reuse system if required in the future.
Ask us which process technology is best for your plastic wash water
Continuous research and development mean that any equipment you buy from us will never become redundant and can easily be modified and upgraded.
Colour removal
The presence of color in wash water as a growing concern for many plastic recycling companies. Many conventional technologies do not affectively remove color and it can remain visible in the final rPET flakes. In collaboration with universities, we have developed a groundbreaking technology for color removal.
This process requires no consumables or replacement parts, it only requires electricity to operate for the color removal efficiency is superior to any other processed technology on the market today. Our advanced electrical oxidation process uses especially quoted graphite electrodes. As wash water comes in contact with these electrodes, color is effectively oxidized and completely removed from the wash water. This oxidation process has been implemented by us in various locations around the world. We have lab scale and pilot scale test modules available, and we welcome the opportunity to show you how we can remove color completely from your wastewater and wash water.
How to choose the correct process technology
It should now be clear that integrating a process and wash water cleaning the system into your washing line requires specialist knowledge. We have the experience to successfully do this for your project. The complexity of selecting the correct process technology in addition to this, it is of critical importance to ensure that the correct process technology is used to clean your wash water. Incorrect selection of the process technology can result in a wash water cleaning system that does not allow for effective reuse. Even where the correct process technology is selected, it must be customized and optimized for the plastic recycling sector.
The only guaranteed way to know which process technology will work with your wash water specialist laboratory testing completed. We offer this specialist service from our in-house laboratory. We can run tests on your wastewater for a very small cost, thereby removing any risk of wrong process technology selection.
This is a totally no obligation service, with no obligation to purchase our equipment after the tests are complete. All we need is a sample of your wash water. We can even arrange collection and transport of the wash water from your site to our laboratory. We complete these tests each week for customers all over the world so please do not hesitate to get in touch with us.
If you were planning a plastic recycling washing line but do not have any wash water available to test yet, do not worry, we can help you design your system once we receive some basic information from you. We are here to help so please write to us any questions you may have.
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