Worms and insects give new life to plastic waste

The agriculture and food packaging industries consume huge amounts of plastic. Finding ways to reuse this material and reduce waste remains a major challenge.

For example, around half of used food packaging that ends up in municipal waste cannot be recycled because it contains food remains or is a mixture of different plastics. This plastic waste is destined for landfilling or incineration and can often end up in the soil.

Our tools were microorganisms, insects and earthworms.

RECOVER project coordinator Maria López

'Current recycling routes are insufficient for dealing with these issues,' explains RECOVER project coordinator Maria López from the University of Almeria in Spain. 'We need to find new solutions.'

RECOVER received funding from CBE JU, a public-private partnership between the EU and industry.

Turning plastic waste into useful products

In response, RECOVER has pioneered new ways to turn plastic waste into useful products and remove existing plastic contamination. Biological solutions were employed for this.

'Our tools were microorganisms, insects and earthworms,' says López. 'We combined their natural capabilities to transform and eliminate plastic in three key scenarios.'

The first scenario focused on plastic that cannot be easily recycled. A combination of insects and microorganisms known to feed on and break down plastic was trialled.

This biological cocktail was used to break down plastic waste and create a range of new possibilities. Manure from the plastic-eating insects known as insect frass was used for fertiliser preparation, while chitin, an antimicrobial compound extracted from insect exoskeletons, was used to produce biodegradable food packaging.

Microorganisms can act as probiotics for earthworms, helping them to feed on the plastic and turn it into fertiliser.

RECOVER project coordinator Maria López

'This food packaging can also extend the shelf life of food because it has antimicrobial properties,' adds López. 'We tested this on chicken breast in the project.'

The chitin and even parts of the insects were also used to produce film for agriculture and biodegradable plant pots, respectively. 'The idea is that these pots can be used together with the fertiliser produced from insect frass,' explains López.

Removing organic waste contamination

A second scenario looked at organic waste streams, which often contain plastic. This contamination can be hard to separate and remove, resulting in plastic contamination in compost.

To tackle this, the project eliminated this plastic by using a particular type of earthworm and microorganisms.

'Microorganisms can act as probiotics for earthworms, helping them to feed on the plastic and turn it into fertiliser,' notes López. 'This compost can then be combined with the insect waste from our first scenario to produce a high-value compost.'

The third scenario involved removing plastic contamination from the soil using a different earthworm species. The project also examined ways of monitoring and modelling microplastic contamination in the ground and compost.

Biodegradable plant pots, fertilisers and food packaging

Key successes in the project included the development of a device for microplastic monitoring, biodegradable plant pots, fertilisers and food packaging film. 'All these products are moving towards commercialisation,' remarks López. 'Eliminating plastic from the soil, however, proved more challenging.'

All these products are moving towards commercialisation.

RECOVER project coordinator Maria López

This is something that López believes the public should be aware of. 'Plastics are in the environment, and there is still work to be done here,' she adds. 'Our approach could be part of a future solution.'

Indeed, a great deal has been learned through the RECOVER project. 'There are many biological solutions that could help us reach our recycling targets,' says Lopez. 'This is the tip of the iceberg from a biotech point of view.'