Recycling of marine litter


Thermochemical recycling of plastic waste

We all know the pictures: Vast amounts of trash in our oceans, marine animals and birds whose stomachs are full of plastic debris, suffocated whales and seals in drifting ghost nets. And these are just some of the impacts.

The most significant sources of litter in the oceans include careless littering and flooding, as well as rivers from countries that lack structures to collect and sustainably recycle litter on land.

More than 11 million tons of plastic end up in the oceans each year, and the question of whether and how to recycle this waste has not played a major role in industry and research. There has also been a lack of awareness among the general public that plastic is a valuable resource.

The everwave association from Aachen (formerly Pacific Garbage Screening/PGS) is pursuing a holistic approach in the fight against marine litter and has now joined forces with its partners at RWTH Aachen University, the Unit of Technology of Fuels (TEER), the Institute of Applied Microbiology Applied Microbiology (iAMB ) and the Institute of Hydraulic Engineering and Water Resources Management (IWW) to investigate how plastic waste can be recycled.

Since marine litter is usually contaminated with buildup, partially decomposed into microplastics, and not composed of a single type, mechanical recycling is usually not possible. Thermal treatment (i.e. burning the waste), which is suitable in these cases, can recover energy and separate pollutants, but this does not return plastic as a resource to a circular economy.

The possibility of chemical recycling, in which the plastics are (thermo-)chemically broken down into their components and can thus be reused, was now investigated. Subsequent upcycling by biotechnological processes was also considered as an innovative approach. The first, positive findings were published in the scientific journal "Processes". The marine litter for the studies was collected by volunteers on the coasts of Norderney and Sylt and made available for our research.

The study: