PerfluorAd®-Process

The aim of the research project "PFAS-Lösch" was to develop an energy efficient and, equally, resource efficient method for removing PFAS (also known as per- and polyfluoroalkyl substances) from highly complex polluted fire-fighting water. In a second step, this process then ought to be evaluated in terms of ecological balance.

The use of foam extinguishing agents with the PFAS is indispensable in order to be able to extinguish effectively large fires of fuels and solvents in e. g. airports and inland ports or in industrial storage facilities. However, PFAS sometimes do not degrade in nature even after 1000 years and some of them are also very toxic to humans. They are harmful to the environment and should therefore not be released into soil and water under any circumstances. Extinguishing waters containing PFAS have to be collected and to be disposed of professionally in order to reduce the input quantity of PFAS in the environment.

However, established procedures for the treatment of extinguishing foams are not PFAS-specific and are very cost-intensive. The current common method for the separation of PFAS compounds is adsorption on activated carbon. Due to the very low adsorber capacities of PFAS, very large filter systems are required.

The Fraunhofer UMSICHT and the Cornelsen Umwelttechnologie GmbH have developed a new process enabling an efficient and economic PFAS removal from the fire-fighting water on site. This process is based on an existing joint development for the purification of PFAS-contaminated groundwater, and it combines an upstream purification stage with a residual treatment by small amounts of activated carbon. The Fraunhofer UMSICHT developed the process chemicals adapted to real extinguishing water, tested them on a laboratory scale and provided suitable methods for process analysis. Then, the combination process was tested in the mobile pilot plant at the Cornelsen Umwelttechnologie GmbH (see picture). Among other things, the joint activities resulted in a first place at the Innovation Award 2017/2018 and a third place at the Environmental Business Award NRW 2022, awarded by ZENIT e. V., the Network for Economy in North Rhine-Westphalia.

Process transferable to other applications

In the pretreatment stage, the "PerfluorAd^®" additive solution is added to the contaminated water which causes the dissolved PFAS compounds to precipitate. As a result, less processing agents have to be used and less PFAS-contaminated hazardous waste has to be disposed of. This leads to considerable cost reductions compared to conventional methods, especially in the treatment of fire-fighting water with a very high PFAS load. The "PerfluorAd^®" process combines even more positive aspects: The specific precipitants are selected from the range of green chemicals – that means, among other things: They are based on natural raw materials, pose no danger to humans or the environment and are naturally degraded after use. In addition, the project result can be transferred to other applications for the purification of PFAS-contaminated water:

• Aqueous media from the maintenance of AFFF tanks, reservoirs, sprinklers
  and equipment cleaning
• Industrial waste water
• Reverse osmosis and nanofiltration concentrates
• Landfill leachate
• Groundwater

Ecologically and economically advantageous

The aim of the life cycle assessment studies carried out by the Fraunhofer UMSICHT was to compare the "PerfluorAd^®" process for the treatment of extinguishing foam water developed in the previous project with alternative treatment processes – adsorption based on activated carbon and thermal high-temperature combustion (benchmarking) – and thus to enable reliable statements to be made about the ecological advantages of the process.

The results of the life cycle assessment show that the PerfluorAd^® process outperforms the other two treatment technologies in all environmental impact categories except zone degradation. (Details of the assessment: see "Further information")

• Cornelsen Umwelttechnologie GmbH