2 février 2015
Professor at the University of South Brittany in the “Haute Bretagne” engineering laboratory, Stéphane Bruzaud is one of the researchers studying the micro-plastics collected during the 7-month Tara Mediterranean expedition. Stephane is analyzing the samples to understand their chemical structures, and thus identify the different types of micro-plastics present in the Mediterranean sea.
But Stéphane’s research does not stop there: he is working to find solutions for tomorrow, especially in the field of bioplastics. Let’s keep in mind that 5 billion single-use plastic bags are still being distributed in supermarkets in France. But not for much longer! The National Assembly voted last October to ban single-use plastic bags starting in 2016, as part of the bill on energy transition.
Why has the plastics industry developed so strongly in the last 50 years?
Today’s plastic has amazing qualities! We should not blindly discredit it. Plastic is not expensive, it is durable and hygienic. In fact, the main problem is plastic’s use in packaging. Take the example of a single-use plastic bag for shopping. It will be used for only a few minutes, but will take dozens or even hundreds of years to degrade. The ratio between the duration of its utilisation, and the duration of its lifetime must become more reasonable.
Biodegradable, oxo-fragmentable, or oxo-degradable plastic – The consumer can get lost, even when trying to be informed about the best choices to make.
This is true, and precisely the goal of certain manufacturers trying to cover their tracks and make the message confusing. A French (European) standard does indeed exist, defining the characteristics of “biodegradability.” This standard requires the result to be a biodegradation of the material under certain conditions within a given time scale. In other words, either the plastic passes tests administered by certification bodies, and thus can be considered as biodegradable according to the standard; or they do not pass, and they are not biodegradable.
When speaking of biodegradability, it’s only under “certain conditions,” for example, in a composter. But it’s rare that plastic bags, even biodegradable, end up in a composter.
This is what limits the utilisation of biodegradable plastics today. We need an industrial sector committed to recovering these materials. Consumers must be well-informed so they can differentiate biodegradable plastics from the others, and accomplish effective sorting.
Can you give us the definition of oxo-degradable or oxo-fragmentable plastic bags?
An oxo-fragmentable or oxo-degradable bag has incorporated pro-oxidant additives that will accelerate the degradation of plastic, without necessarily bringing it to completion. So, in a way we reduce the size of the plastic, and maybe even the resulting visual pollution, since the macroplastics will fragment into microparticles that are less visible. But their degradation will not be complete. In other words, they are not biodegradable! The plastic will persist in the environment, in the form of micro-plastics, on land and in the water.
You are working on plastics of the future? What does this involve?
We have to develop more environmentally friendly materials, starting with their mode of production, through the end of their life. We need to target their utilisations. Statistics show that about 300 million tons of plastic were produced worldwide in 2012, but only 1 to 2% of these were bioplastics. Obviously it’s unrealistic to want to replace all plastics with bioplastics, but it’s essential that bioplastics gain a large market share in the sector of packaging for short periods of use.
What raw materials go into the manufacture of these plastics?
Materials extracted from biomass: plant materials, sugars or starch, and vegetable oils. In Lorient, I myself work on recycling waste from the Breton food industry, for example from the processing of fruits and vegetables. For several years we’ve been showing the feasibility of bioplastic production by fermentation using this type of waste, and adding marine bacteria that come from clams or cockles from the Brittany coast. We can thus produce bioplastics using a biotechnological process.
What are the limiting factors in the production of this type of plastic?
Unquestionably, the cost! Petro plastic costs about 1 euro per kilo. A bioplastic costs a minimum of 2.5 to 3 euros per kilo. This significant price difference is a real hindrance. But it is also a question of markets. When the market expands, production costs will fall. Often, to develop a market it’s necessary to encourage the development of a particular product or technology by taxing or with regulations.
Could the 2016 prohibition passed by the National Assembly kick-start the bioplastics industry?
Yes, not only because France will have to limit non-biodegradable plastic waste, but also because many applications will still require plastic. We will necessarily fall back on biodegradable plastic.
Interview by Noëlie Pansiot