The effect of transformation on plastic transport in and from agricultural soils

Application of wastewater treatment sludge on soils are highly beneficial to a bio-based society and sustainable agriculture but also increase the concentration of plastics.

Plastic concentration projections should be based on accurate transport rates of plastic particles in and from soils to inform potential restrictions of these activities and whether pre-treatment of sludge such as pyrolysis is necessary.

However, such rates are lacking or are determined for pristine, i.e. newly produced plastic particles that likely are less mobile in soils.

The current project will determine how transformation processes during wastewater treatment, in the field or during pyrolysis alter the surface chemistry of plastics.

Transformed particles will be isolated from fresh or pyrolysed sewage sludge and long-term field trials with sludge and their altered surface will be characterized.

The kinetics of transformation will be determined in outdoor mesocosms where we will also produce transformed plastics labelled with metals.

These particles will then be used to quantify how transport distances of transformed plastics in and from soils differ from pristine particles.

Finally, we will produce a modelling tool that allows a better prediction of plastic concentrations under different scenarios of sludge use on land informing decisions aiming for a toxic-free environment while maximizing the potential of plastics and reuse of sludge for sustainable agriculture and bio-based societies.