Adding Value to Plastic Waste Streams

RWTH to coordinate a new Horizon 2020 project.

 

The continuing demand for plastic products, the lack of appropriate recycling processes and the ubiquitous pollution of the environment with plastic waste pose a global challenge. Every year, approximately 358 million tons of plastics are produced worldwide. In many countries that do not have a functioning disposal system in place, waste ends up in landfills or even in the countryside and the sea. Depending on environmental conditions, a PET bottle takes 400 years to decompose.

In accordance with the EU targets, by 2020, 50 percent of PET plastics, for example in beverage bottles, are to be recycled, and so are 70 percent of polyurethane (PU) foams used in mattresses or car seats, for example. At present, however, less than 30 percent of PET waste and less than five percent of PU are treated. It requires considerable effort to convert the traditional value chain to a sustainable one, for example based on fully biodegradable plastics.

As part of the EU HORIZON 2020 project MIX-UP, short for "Mixed plastics biodegradation and upcycling using microbial communities," an international, multidisciplinary consortium is now exploring new, sustainable recycling methods.

MIX-UP investigates sustainable alternatives to mechanical and chemical recycling. Coordinated by Professor Lars M. Blank, RWTH Chair of Applied Microbiology, th project receives funding in the amount of around 7.5 million euros, from which RWTH will receive around two million euros. Other RWTH institutions involved in the project are the Chair of Biotechnology, the Institute of Technical and Macromolecular Chemistry, the Aachen Process Engineering departments (AVT), as well as the administrative Department 4.2 – Management of Third Party Funds. In addition, ten other European institutions and four high-profile partners fro China participate in the project, including Tsinghua University, Beijing, a strategic partner of RWTH.

MIX-UP will use plastic mixtures of five of the most important fossil-based plastics and future biodegradable plastics for microbial transformation processes. The enzymatic, microbial degradation of mechanically pre-treated plastic waste will be combined with the subsequent microbial conversion into high-quality chemicals and polymers.

Known plastics-degrading enzymes will be optimized with respect to high specific binding capacities, stability and catalytic efficacy for a broad spectrum of plastic polymers under high salt concentrations and temperatures. New enzymes with activities on recalcitrant polymers will be isolated. The EU-funded project also seeks to optimize the production of these enzymes and develop enzyme cocktails tailored to specific waste streams. The released plastic monomers will be selectively used by stable microbiomes as substrates to produce, among other products, value-added chemicals or microbial polyesters. Any remaining material recalcitrant to enzymatic activity will be recirculated into the process after a physico-chemical treatment.

The technologies used in MIX-UP thus increase recycling rates and add value to the previously inadequately processed waste streams of unsorted plastics.