Recycling dirty farm plastics

European agriculture annually generates around 90 000 tonnes of plastics film waste, which is difficult to recycle commercially. Hence, recycling schemes are either government subsidised or expensive for consumers, meaning farmers seek cheaper but environmentally harmful and/or illegal alternatives.

Either way, the sector needs an efficient recycling technology, which the EU-funded START project aimed to provide. The group planned to develop two technologies, intended to reduce costs and make agricultural plastics film recycling economically and environmentally sustainable. The developments were to include a portable unit to clean, separate and compress the waste before collection and logistical software models to optimise collection.

The system's innovations included use of airflow for cleaning instead of water, and ability to remove contaminants at the source. The 13-member consortium ran for 42 months between late 2008 and mid-2012.

Consortium work began with characterising film waste in terms of amount of soilage and degree of adhesion. The purpose was to assess soilage removal, and the project tested airflow in those terms. The work revealed a large variability in soilage quantity, which was determined to require three different methods of collection and processing depending on the amount.

Instead, the team developed a method of processing the film as a flat sheet collected directly from the field. Following trials of soilage removal, the consortium developed a three-stage process involving air-blowing technologies and automated cutting of film sections. The project developed and tested prototype subunits, which were integrated into a complete system.

Subsequently, START refined the machine's performance, whereby the prototype was finally able to process a continuous film 1.6 m wide and 25-250 microns thick. The development constitutes a successful proof-of-concept.

Work also addressed logistical modelling and web-based film processing software. Following a process of defining requirements, the software was designed and successfully tested. The consortium also conducted a life-cycle analysis of the complete system, concluding that the system would have positive environmental and economic benefits.

The START project developed a novel three-stage process for collecting and treating agricultural plastic film waste. Apart from the environmental benefits, the development offers significant cost savings and market potential.