In general, extinguishing water contains a lot of toxic and carcinogenic PFAS substances (per- and polyfluoroalkyl substances), as well as various unhealthy heavy metals. These substances have to be avoid to end up in nature or into our common drinking water in the end. Therefore, MSB is investigating the possibilities offered by the market on how to treat extinguishing water that is the result of rescue services putting out fires.

Only one technology coped with both PFAS and metals

Six different companies were invited to MSB's facility in Revinge, just outside the city of Lund in South Sweden. The set-up was to test how different techniques offered by these companies would be able to clean firewater. In this particular case, the firewater was a mixture of water from a previous car fire and from a burning house. After treatment by the 6 different methods, the outgoing water was sent to an independent laboratory that analyzed the different degrees of treatment.

Swedish Hydro Solutions' BioMedia® filter treated both PFAS and metals with an extremely high degree of purification. The BioMedia® based filter reduced the level of PFAS slv11 from 1,050 ng/l to below the detection limit of 2.5 ng/l. Simultaneously, metals – such as cadmium, chromium, nickel, iron, zinc and copper – were reduced by levels around 99% for each individual metal.

For several metals, more than ten times more efficient purification was achieved with BioMedia® when compared to the other purification methods evaluated in the test.

The practical solution that Swedish Hydro Solutions used for this MSB test consisted of two simple filter housings that were filled with BioMedia; a product manufactured from wood and in many ways similar to activated carbon. However, thanks to the unique production method, BioMedia® obtains a surface chemistry that effectively binds-up a large number of different environmental toxins.

In addition to BioMedia®, the first filter housing was also topped with an oil absorbent from Swedish Hydro Solutions' partner Biosorbe. There was a very obvious improvement when applied to MSB's extinguishing water, which had a distinct smell of petroleum residues.

– BioMedia® also cleans oil without problems, but the addition of Biosorbe's specific oil absorbent offers an effective primary cleaning step when water contains a large amount of petroleum products. By using the extra oil absorbent as a first cleaning step, the lifetime of BioMedia® is extended. Allowing it to perform its primary goal of removing PFAS and metals for an extended period of time.

Conventional technologies are the use of active coal to treat metals and expensive ion exchange technology to effectively take care of organic pollutants such as PFAS.

In order to come close to the level of purification BioMedia® achieved for both PFAS and metals, the necessary combination of activated carbon and ion exchange technology would have become an expensive solution.

“Biomedia® extremely effective cleaning both PFAS and metals with just a few filter steps, becomes a very economic solution”, says Jakob Sjöberg.

Scalable technology

BioMedia® is normally delivered in standard filter housings of one cubic meter. This way it can easily be placed on a trailer, if MSB would want a mobile solution to filter firewater directly on the spot at any fire scene.

One or two Biomedia® filter housings would not encounter any problem to handle the firewater from for example a car fire.

– After extinguishing a car fire, a few hundred liters of firewater are normally generated. One BioMedia® filter has the capacity to take care of approximately 1,000 liters of water in 15 minutes. Therefore, the water from a typical car fire, would only take a few minutes to be handled; once the filter has arrived on site and has been connected to a pump.

Another option would be to collect the extinguishing water in a tank truck, and then clean it at a permanent treatment plant later; the Biomedia® would work just as well for that.

– “A BioMedia® filter is easy to scale depending on the purification needs. The more water that needs to be purified (per unit of time), the more filters are added. BioMedia® is a ready-made product that is available for immediate delivery. Both for small-scale local interventions, as well as for large-scale purification.”, says Jakob Sjöberg.