The DAFIA project focused on two key waste streams with high environmental impacts. The first stream – municipal solid waste (MSW) – typically consists of biodegradable garden and park waste, as well as food and kitchen waste from households, restaurants and retail premises. Around 50 % of this waste is currently landfilled, while only 30 % is recycled. The remaining 20 % is incinerated.
“Despite the strong societal shift away from landfilling to recycling, it is still a challenge to turn MSW into products of higher value than bioenergy,” explains DAFIA project coordinator Laura Martí, researcher at AIMPLAS in Spain.
Another waste stream – marine rest raw material (MRRM) – is generated by fisheries. In the EU alone, 2 million tonnes of MRRM is produced each year. Some of this waste is turned into silage, or processed into fish and animal feed, or biofuel feedstock. Only a small fraction of MRRM is used for human consumption or other added-value applications.
“Due to the lack of specialised infrastructure, MRRM is often wasted or sent directly for animal feed without any attempt to extract valuable components,” notes Martí. “Furthermore, thousands of tonnes of fish are simply discarded due to their low commercial value.”
Value in waste
The DAFIA project began by looking at ways of converting MSW material into valuable chemical building blocks to produce polyamides. These have a wide range of industrial applications, including in the automotive sector. “Producing polyamides from waste is a more sustainable alternative to fossil-based compounds,” says Martí. From the MRRM waste stream, extracting and processing compounds to be used in flame retardants and edible coatings could benefit the construction and packaging industries respectively.
The pretreatment of waste streams, as well as fermentation and purification processes, were all investigated. New microbial strain engineering and cost-efficient ways of converting feedstock fractions into useful compounds were developed. A key focus was achieving maximum yields of the targeted compounds, as well as economic viability.
After 4 years of collaborative work, the project team was able to achieve several key breakthroughs. These include optimised extraction techniques to maximise the purity of gelatine, and being able to scale up production in order to produce edible packaging. Fish-waste-based flame retardants were also successfully developed.
“The formulation of these bio-based flame retardants has resulted in two patents, as well as further studies to commercialise these products,” adds Martí. Taste-neutral proteins were also successfully extracted from MRRM, which could have market potential as alternatives to whey proteins.
Competitive recycling processes
Overall, DAFIA has demonstrated the technical feasibility of recycling waste to produce high-value products. While most of the products pioneered in this project – with the exception of the bio-based flame retardants – will require further development before commercialisation, the project’s key success has been to underline how waste extraction is critical to helping Europe meet the objective of a circular economy.
“One has to realise that this is a long-term strategy,” says Martí. “Many technical gaps must be filled in along the way if we are to achieve practical implementation. In this regard, the environmental impact studies we conducted will be important to help drive the circular economy forward.”
For example, issues such as the carbon footprint of the recycling processes were analysed. It was found that, in general, energy supplies represent the main contribution to CO2 emissions. “This means that the implementation of renewable sources of energy, can dramatically reduce environmental impacts,” explains Martí.
Economic analyses were also carried out, focusing on raw material costs. Some processes, such as the synthesis of bio-based flame retardants, are price competitive. Other processes are at a very early stage and cannot at present be produced at market-competitive prices. Public and private funding will be needed to continue with this research.
“These calculations help us to detect the next steps that need to be taken to achieve optimisation,” notes Martí. Indeed, economic analysis data from the completed project is still coming in. This will continue to be collected, enabling project participants to select the most promising recycling processes to move forward with.