So, what is PHA again?
Bacteria produce PHA as a source of energy and as a carbon store through the fermentation of renewable feedstocks such as sugars or fatty acids, or any other carbon-containing substrate. This natural process can be mimicked in an industrial setting using feedstocks that can range from wastewater streams to plastic waste, renewable methane and carbon dioxide. They are a class of natural materials that have existed in nature for millions of years. These materials are both bio-based and biodegradable, similar to other naturals materials such as cellulose, proteins and starch.
According to GO!PHA, PHA products range from amorphous to highly crystalline, and run from high-strength, hard and brittle materials to low-strength, soft and elastic. The versatility of the PHA family accommodates a wide range of market applications, due to their biocompatibility, biodegradability and green credentials. Depending on type and grade, PHAs can be used for injection moulding, extrusion, thermoforming, foam, non-wovens, fibers, 3D-printing, paper and fertiliser coating, glues, adhesives, as additive for reinforcement or plasticisation or as building block for thermosets in paints and foams. The main markets where PHAs have already achieved some degree of penetration are packaging, food service, agriculture and medical products.
PHA is equally versatile when it comes to the end of life. It can be reused. It can be recycled back to the polymer for new applications. It can be recycled back to raw materials to be used as renewable feedstock. It can be recycled to the environment through industrial or home composting. It can be recycled through incineration creating renewable energy. And lastly, it can be recycled to nutrients for living organisms through full biodegradation.
Drawing the line
PHA may well be a natural polymer, but in the eyes of the EU it is classified as an artificial or a modified polymer and hence not allowed to be used as a single use plastic replacement.
“The basic problem is the fact that PHA is considered to be a fermentation-based product,” said Mukherjee.
ECHA considers fermentation - in their REACH Guidelines – to be an industrial process, even though, in the EU Legislation on Flavorings, for example, products produced through fermentation processes are considered to be natural. And what about cheeses, wine and beer, or sauerkraut - should these therefore also be reclassified as artificial? They, too, are all the result of fermentation using living organisms.
“Of course: PHA is the result of a fermentation process. The point here is that fermentation is a natural process - one that occurs everywhere in nature. PHA is a natural polymer that is produced by natural routes in nature, and industrial fermentation processes simply make them economically viable,” Mukherjee explained.
For commercial purposes, the process is scaled in order to be able to produce commercial volumes, but it remains a bacterial process that produces a bacterial polyester, he said.
“We have talked to the Commission about this, but with disappointing results.”
The stance adopted by the European Commission is even more puzzling in view of the fact that Europe has spent over €110 million sponsoring research into the valorization of waste to produce PHA. One such project – EUROPHA - developed a PHA production process using mixed microbial cultures, enabling the use of low-cost agro-food waste with no market value, no food competition, and no price volatility effects. Further research was aimed at developing high quality food-grade biodegradable PHA for packaging that could be disposed of as organic waste.
Moreover, a recently concluded study by the EU expert committee entitled “Science Advice for Policy by European Academies” on the ‘Biodegradability of plastics in the open environments, SAPEA, December 18, 2020’ clearly states that the field of biodegradable polymers is one that is rapidly evolving and high-tech and that ‘policy should avoid placing barriers to future developments and innovations.’
Europe versus the world
Outside Europe, PHA is starting to gain real momentum, with various producers - Kaneka, Newlight Technologies, Danimer Scientific, for example - having successfully scaled up production to industrial or even commercial levels. Around the world, it is being used to replace fossil-based plastics in a host of single-use plastic applications such as straws, serviceware, even coffee pods.
The rest of the world, explained Mukherjee, has designated biodegradability - see, for example, the SUP legislation passed in China in January 2020 - as the criterion to ban or exempt use of plastics.
“There are standards for biodegradability – also for marine biodegradability – that are used to certify this. The EU is the only one using this natural polymer criterion to exclude PHA - but to include cellulose,” said Mukherjee.
Yet PHA’s biodegradability profile is very similar to cellulose, he pointed out. “Cellulose and PHA have the same order of magnitude biodegradation pattern. All other plastics replacements and biopolymers are several orders of magnitude longer in biodegradation.”
It seems odd: other parts of the world are happy to embrace PHA as a full-fledged biodegradable, sustainable biopolymer and to support and promote its further development and use in single-use applications. There, the science is straightforward. Europe, however, continues to tenaciously adhere to its own criteria and interpretation of the concept of ‘natural’ – despite what scientists, including EU’s own expert panel SAPEA ,say.
How this will affect future research and business developments in PHA materials in Europe remains to be seen, but there seems little doubt that not recognising these materials’ potential and eminent suitability for a least some of the products included in the ban, could at least result in Europe’s falling out of step with measures taken elsewhere. This is surely not the intention of the directive. Achieving a clean, non-polluted environment - in the oceans and on land - demands collaborative, coordinated action.
It is time to get on with it.