H2020 NENU2PHAR Project: Towards a sustainable European value chain of PHA-based materials for high-volume consumer products

Thanks to their mechanical, thermal, and protective properties, plastics are indispensable in the manufacture of large volumes of consumer products and packaging. However, most of these plastics are produced using fossil fuels, can be difficult to recycle, and can cause environmental hazards such as microplastic pollution. While several efforts are underway to recover, reuse, and recycle these plastics, an alternative approach that is gaining ground is to find biodegradable source materials. The NENU2PHAR project has successfully demonstrated a value chain that delivers a family of polymers called polyhydroxyalkanoates (PHAs), using bacteria cultured on sugars produced by microalgae.

“Despite being widely recognized as a viable substitute for fossil fuel-derived plastics, there is still no sustainable PHA value chain in Europe,” explains Pablo Álvarez Díaz of the French Alternative Energies and Atomic Energy Commission, coordinator of the NENU2PHAR project. Funded through the Bio-based Circular Europe Joint Undertaking, the project involved 17 research and industry partners. Fuel that doesn’t compete with food PHAs are a class of renewable, biodegradable, and bio-based polyesters that are considered members of the “green polymer group.” They have attractive physicochemical, thermal, and mechanical properties, similar to polypropylene (PP) and low-density polyethylene (LDPE), which make up the majority of plastic packaging used today. "PHAs are particularly attractive because they are environmentally friendly at the end of their life, as they degrade in soil, aquatic environments, and in domestic and industrial compost," says Jean-François Sassi, co-coordinator of NENU2PHAR.

However, because bacteria require sugar to grow, producing large quantities of plastic this way faces a serious challenge. "Currently, the carbon feedstocks used as fermentation substrates come from starch produced from crops such as wheat and potatoes, thus competing with traditional agri-food supply systems and increasing food prices," adds Álvarez Díaz. NENU2PHAR demonstrated that microalgae could be an ideal fuel source for bacteria. Growing algae in bioreactors captures large amounts of CO2 from the atmosphere and converts it into the starch needed by hungry biopolymer-producing bacteria. "The production of pure white starch from green microalgae was an important milestone, as the industry requires colorless and transparent plastics at the beginning of the production process," notes Sassi.

The team also developed a process for extracting PHAs from bacteria that uses more environmentally friendly solvents than conventional chlorinated varieties. The PHAs are then formulated into bioplastic production feedstocks. Encouragingly, there is already a ready supply of the feedstock: microalgal biomass is routinely produced by European wastewater treatment facilities during wastewater treatment processes. The NENU2PHAR value chain could turn a waste stream into a revenue stream. The gateway to a more circular economy As a demonstration of the versatility and suitability of PHAs, the team has unveiled a collection of microalgae-derived bioplastic products. This includes sliced cheese trays, film lids, pots and pouches for moist foods such as yogurt, roll-on bottles for deodorant, filaments used in 3D printing, medical mesh, and agrotextiles. "We received very positive feedback at various events, and people would often say, 'Wow, you've really done it.' You can't argue about the viability of these bioplastics while holding one of our yogurt pots," says Álvarez Díaz.