Small plastics, big pollution: the case of biomedia


Small circular pieces of plastic stranded on beaches represent a form of ocean pollution that Surfrider Europe has been fighting against for several years. Yet still so little known, the so-called biomedia or filtering media regularly escape from the sewage treatment plants where they are used to treat wastewater, to end up with other marine litters on beaches and in the seas.   

A few millimeters of plastic to filter wastewater  

Since the early 2000s, biomedia have been used in many water treatment plants. Their role is to allow microorganisms to fix, proliferate, and digest suspended matter in water. In other words, to filter wastewater. Unfortunately, when the system malfunctions these small cylindrical plastics, a few millimeters in diameter, can be released in large quantities into the natural environment and cause pollution.   

Several incidents can lead to these cases of pollution: heavy rains cause overflows in treatment plants, with the wastewater carrying the filtering media with it. Losses of biomedia can also be observed during impoundment or work in treatment basins. Biomedia can clog the discharge grid if they are not sufficiently agitated, if the installations are faulty or if the discharge grids are not adapted to the process. When combined, these elements can lead to large scale pollution that could easily be avoided!

Indeed, solutions to these incidents are often very simple and inexpensive: starting with prevention and information on the use of biomedia and accompanying users during the launch phases. Then, if there is an incident, the solution remains to adapt the systems and put in place recovery procedures, which can be more costly.   

A subject never studied before  

For several years, Surfrider Europe has become a reference association on the subject of biomedia. But how did it come to deal with this issue?  

It all started with François Verdet, a volunteer from the Surfrider Basque Coast chapter, who in 2007 spotted these strange pieces of plastic washed up in large quantities on the beach. For almost two years, he led the investigation as a Coastal Defender of Surfrider Europe and finally discovered the cause of this pollution. After this alert, a group of experts was created to investigate and understand more about the biomedia problem. 10 years later, the first expert report on the subject was published.   

You too can be an alarm bell ringer  

It was thanks to volunteer testimony that the problem was raised and the association began its work to try to reduce this source of pollution. Since then, many cases of pollution by biomedia have been identified around the world: in France, but also on the Spanish coast, in the heart of Lake Leman and also in the United States and Canada. The first case identified by François on the Basque coast was not an isolated case. 

Even today, the Surfrider Europe team continues its work to reduce pollution due to biomedia. To move things forward and become even more expert on the subject, it needs new testimonials. So, if during a walk on the beach, you come across these little pieces of plastic... alert the association! Fill in this form or send us an email at 

Keep your eyes open, it can be useful... It's thanks to testimonies of pollution that the association advances on its various fights. The biomedia battle is still brand new, and Surfrider Europe does not intend to stop there!   

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