A reduced footprint for PET recycling and rPET
19 Apr 2021
More post-consumer PET is recycled today thanks to increased efficiencies and cost-effective processing methods. Coupled with tougher recycling and production requirements, recycled PET is now more widely available and competitively priced. Many recycling companies rely on GEA centrifuge technology to handle their process water, enabling them to achieve quality and environmental standards while minimizing their running costs.
Polyethylene terephthalate, or PET, is one of the most common consumer plastics in use and is highly recyclable. Its unique attributes, which include durability, transparency, lightweight, non-reactive, thermal stability and low cost, make it a popular packaging choice for diverse products, including beverages.
Demand for post-consumer PET growing
Given the production of most plastics, including PET, require fossil fuels, the environmental footprint of recycled plastics is a fraction of that of virgin plastics; therefore, reducing overall plastic usage and reusing existing plastic is vital.
Much of the packaging industry is in transition as it searches for alternative solutions that rely less on fossil fuel-based materials and more on renewable resources. In parallel, countries are introducing stricter regulations and placing greater responsibility at the feet of manufacturers to increase the use of recycled material in their packaging. Increased consumer recycling means more post-consumer PET is now available which has a positive knock-on effect on the price of recycled PET (rPET).
To begin with, reclaimed PET is first sorted into color fractions, pressed into bales and sold on to recycling companies or materials recovery facilities (MRF). From there it is washed and further processed and turned into recyclate in the form of flakes. These flakes can be melted down to create uniform-sized polyester pellets, which are then sold to manufacturers for use in the production of:
- packaging
- clothing & shoes
- household goods
- hygiene products
- trunk liners
Making PET safe for food-grade applications requires super-clean recycling processes which can decontaminate post-consumer PET to concentration levels of virgin PET materials. In the bottle-to-bottle recycling process, MRFs separate out PET bottles for processing and create the preforms from which new bottles are then blown out by beverage producers.
GEA helps recycling firms safeguard the environment and their ROI
To create food-grade rPET, reclaimed PET is first shredded into flakes, followed by cold and hot washing and an additional cycle with a solution containing caustic soda to remove dirt, sand, product, labels and adhesive residues. This ensures only pure, high-quality PET remains as it moves through each step.
Both food- and non-food-grade PET recycling processes produce wastewater and sludge. Here, GEA sludge Decanters play a central role, separating the solids from the process water and removing all contaminants from the water circuit during cleaning. As a result, much of the water and cleaning agents can be redirected back to the process and the solids ejected and safely disposed of.
GEA sludge Decanters are robust and efficient, ensuring the safety of our operations while keeping more resources from the washing process moving circularly versus being wasted.”- Michael Fricke, Project Engineer, Veolia Germany
- Michael Fricke, Project Engineer, Veolia Germany
Integrating a GEA sludge Decanter is also important for achieving ROI as it lessens the amount of wash water and expensive alkaline solutions that need replacing between batches. And by utilizing separation during these key upstream phases, equipment and machines downstream are much less prone to clogging.
Two GEA sludge Decanter pro, used in PET recycling, deliver high G-force and torque handling capability. Decanting returns valuable resources back to the process cycle, safeguards downstream equipment and reduces freshwater withdrawals. Less water in the solids reduces disposal costs, while removing contaminants safeguards the environment.
Experience matters
GEA environmental Decanter lines are the result of decades of market-leading expertise in wastewater and sludge treatment in municipal and industrial wastewater treatment plants and in agriculture. Decanters play a crucial role in turning sludge, manure and fermentation residue into valuable resources like fertilizer or energy – with the best possible yields.
The GEA sludge Decanter pro line, used successfully in PET recycling by customers globally, delivers significant G-force and torque handling capability. Its modular, compact design for easy "plug & play" integration into established processes includes several attractive features, such as:
- high energy efficiency: < 0.7 KW/h per cubic meter of sludge dewatered
- throughput capacities (skid, mobile or retrofit)
- robust, stainless steel construction offering high corrosion protection for all components that have product contact
- long service life even under continuous operation
- closed system design with no aerosol emissions
To date, GEA has delivered numerous decanter centrifuges for integration in turnkey PET recycling plants for operators serving end-customers in North and South America, Europe, Asia Pacific, the Middle East and Great Britain.
For long-time customer, Veolia Group, GEA has delivered several decanters for diverse recycling-related sludge processes. Most recently, Veolia asked GEA to provide sludge decanters to accommodate differing capacities at end-customer plants in Germany and Norway, which run continuously. “We know we’re in good hands whenever we choose GEA as a partner,” says Michael Fricke, Project Engineer, Veolia Germany. “GEA sludge Decanters are robust and efficient, ensuring the safety of our plants and keep more resources from the washing process moving circularly versus being wasted,” adds Fricke.
GEA sludge Decanters perform well, even under extreme conditions and continuous operation. As a result, we’re able to deliver high-quality rPET, reduce our operating costs and safeguard the environment.”- Torben Beck, Plant Manager, Veolia end-customer, Infinitum AS, Norway
- Torben Beck, Plant Manager, Veolia end-customer, Infinitum AS, Norway
Is that clear?
Colorless and light blue post-consumer PET attracts higher prices than darker colored PET bottles. Amber-colored PET, while useful to specific manufacturers or industries, can compromise the financial viability of recycling these materials. Also problematic is the use of carbon black pigment in plastic packaging as it is not readily detected by near-infra-red machines commonly used for automatic sorting.
While the wider color choice is good for bottled-drink marketers, this poses challenges and increased costs for recyclers who must segregate the different colors, necessitating the need for more sophisticated color-sorting technology.
