PROJECT DESCRIPTION
BACKGROUND
Around 3% of waste generated in the EU is hazardous, which represents about 12 kg of hazardous waste per capita (Eurostat figures for 2006). EU legislation covering hazardous waste requires Members States to comply with certain rules concerning its collection, handling, recycling and treatment. The conventional method for reducing or eliminating threats from hazardous waste containers involves the triple rinsing and draining of empty containers. In the case of plastic packaging, it involves pre-rinsing, crushing, washing(with different washing agents, detergents or surfactants) and subsequent rinsing and drying. After drying, the material can then be passed through an extrusion line, to produce a recycled material in pellet form. This process requires large amounts of water, cleaning agents and energy. It also produces large volumes of wastewater. Recycled plastic obtained from conventional recycling processes is used in applications with low added value (e.g. pallets), as it generally has inferior mechanical and organoleptic properties.
OBJECTIVES
The LIFE EXTRUCLEAN projects main objective was to demonstrate the viability of a new technique for eliminating hazardous substances from waste polyethylene (PE) packaging for solvents or phytosanitary products. The project planned to use a technology that applies a supercritical carbon dioxide (sc-CO2) in the extrusion phase of the plastic recycling process.
This process was expected to partially, or totally, serve as a substitute for two of the three stages involved in conventional treatments, which should reduce the labour requirement and the consumption of energy and water. The recycled material would then be employed in the production of packaging for hazardous substances, closing the lifecycle. The project aimed to provide a reference for the implementation of new solutions in the plastics recycling industry, leading to more efficient and environmentally-friendly processes, as well as higher quality recycled material.
RESULTS
The LIFE EXTRUCLEAN project demonstrated the viability of eliminating hazardous substances in polyethylene (PE) waste, coming from packages of solvents or phytosanitary products, by using supercritical carbon dioxide (sc-CO2) in the extrusion process.
First, the project showed the effectiveness of the new technology on a pilot plant scale. The project team carried out the implementation of the use of sc-CO2 in the extrusion process and optimised the decontamination process on polyethylene packages that had been contaminated in a controlled way with model liquids representative of the different contaminants present in hazardous plastic waste. The project team assessed its effectiveness in a range of waste treatments with sc-CO2, and it found that 70% more effective than the traditional process at removing contaminants. It allows two out of the three washing/cleaning stages of the traditional process to be eliminated.
The second stage was to implement the technology at the facilities of industrial partner, ACTECO. The project team carried out the necessary modifications of the cleaning line as well as in the incorporation of the use of sc-CO2 in the extrusion process. Modifications in the cleaning line resulted in a 56% reduction in water consumption, a 23.4% reduction in the use of chemical agents and 56% cut in energy consumption. Decontamination trials were performed on real hazardous waste samples, reaching global decontamination levels of up to 70%.
The project team then studied the suitability of the new recycled material for the production of 20 litre and 10 litre packages (at Enplast facilities), the most representative packages for hazardous substances. Packages from the traditional recycled material were also produced. The project demonstrated:
Packages from industrial packaging waste were produced with a range of EXTRUCLEAN recycled material content (70%, 75%, 80% and 100%) and tested for packaging of hazardous substances at the facilities of the project partner, AIDIMME. The testing for the certification according to ADR regulations was performed on a range of parameters: chemical compatibility, drop tests, stacking, waterproofing and internal pressure.
Results concluded that 10 l packages consisting of 75% EXTRUCLEAN recycled material are suitable for containing hazardous goods belonging to the packaging group II PGII (medium hazardous), while 20 l packages with 70% recycled content are only suitable for containing hazardous goods belonging to the packaging group III (less hazardous). Packages comprising 100% EXTRUCLEAN recycled material, independently of design, only could be used for transporting non-hazardous goods, which include those that are hazardous in terms of use or handling but non-hazardous for transport, as in the case of domestic bleach. For use in handling, additional regulations must be considered.
A Life Cycle Assessment showed an overall 44% reduction in environmental impact can be achieved in the cleaning process. In the extrusion step, the use of carbon dioxide as an additional raw material increases the environmental impact of this process. Nevertheless, considering both the cleaning and extrusion stages the final outcome is positive. Although the overall environmental impact is 8% higher than the traditional process (it is higher in some categories and lower in other ones) the increase in quality of the resulting recycled material compensates for this impact. The reduction in environmental impact depends on the different compositions and designs assessed ranging from 56% up to 86% for the packages with 100% recycled material.
The project is in line with the EU Directive on Packaging and Packaging Waste and with the five-step waste hierarchy introduced by the Waste Framework Directive, as it prioritised recycling over disposal of waste packaging. Most importantly, it complies with the EU Action plan for the Circular Economy "Closing the loop, by providing higher added value applications thanks to the development of higher quality products, compared to traditional recycled waste materials.
Further information on the project can be found in the project's layman report (see "Read more" section).
