Interview with Philippe Seberac

“In order to treat microplastics, we first need to know how to characterize
them.”
Published in the dossier of October 2018

Philippe Sébérac, Technical and Performance Director, Water, Veolia

What is microplastic?

There is no strict definition. As far as we are concerned, we treat anything from 0.1 micrometer (0.1 μm) to 5 millimeters. In other words, we go beyond the “micro.” The true micro is actually between 0.1 μm and 1.2 μm for us, but the whole range of microplastics up to 5 mm can have an impact on health and the environment and must therefore be studied.

Where do they come from and what are they found in?

The main source of microplastics is the degradation of macroplastics in the environment. Although there are many possible origins of microplastics, the analytical tools to characterize them are neither locked nor stabilized today. There are no standardized elements to gain an overview of the extent of the problem and what is relevant to treat. A few indications are available. We know, for example, how much microplastic fiber a washing machine discharges, one of the big contributors in domestic use! But what about traffic or what happens to plastic fibers in the air when they fall into the water or on the ground?

Do we know how to treat them?

Veolia already has technological processes and expertise; so, yes, we know how to treat them! But, for any action to be economically and ecologically effective, you need to know where and how to treat, and, unfortunately, we cannot use the same method in all environments and on all types of plastics. Therefore, the first stage is to characterize microplastics. This means knowing where they are, where they come from, what types of plastics they are made of, how to treat them, when, and so on. But the tool that can do this in a sufficiently detailed and precise manner has not been invented yet... So, we are working to understand how microplastics are distributed in the environment to better define where treatment should be done: at the source? on exiting the treatment plant? upstream of drinking water plants? a combination of all of the above?

What characterization methods do you use?

They differ according to the size of the plastic particles. As I said, we are working on a broad spectrum, up to half a centimeter. Qualitative characterization is also implemented. We must first identify the nature of the polymers involved, limiting ourselves to the most common, because their behavior is not quite the same. Another subject relates to additives used for different purposes, such as facilitating polymerization. They often have an impact on human health, such as endocrine disruption, which is the most common. Here we have a chemical “fingerprinting” tool developed by Veolia’s research center that allows us to analyze additives. However, we are not yet able to analyze fibers in a standardized and stabilized manner, and we cannot detect them at varying sizes either. And, for the moment, we cannot collect intercomparable results to define a strategy.

How can this research be developed?

The Group is currently involved in several research programs in France. We are working with labs in France and Denmark to characterize and quantify the nature, types of molecules involved, and size of microplastics. We are also studying the eco-toxicological impacts of microplastics on all types of plankton, microfauna, and some small fish. In partnership with a coastal community, we are currently testing a basin-wide characterization. After analyzing the flows entering the WWTP and which are released into the natural environment, we follow the evolution of all this on the coastal strip that feeds the pelagic zone. In short, we are looking for the answers to the following questions: which microplastics? Where are they produced? How are they disseminated in the environment? How do they interact with the water treatment system for drinking water and sanitation? Veolia ultimately hopes to develop, with its customers, a microplastics treatment strategy by 2020.

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