Spanish fog against polluting particles

The University of Alcalá designs Counterfog, a pioneering system to eliminate emissions due to accidents, terrorist acts or sabotage

     A special nozzle, a water system and compressed air. With this device it is possible to eliminate the polluting particles suspended in the air due to accidental causes, such as fires, leakage, spills or terrorist acts and sabotage. This is the Counterfog , a success of Spanish technology developed by a team of researchers from the Department of Mechanical Engineering of the University of Alcalá de Henares (Madrid), directed by Professor José Luis Pérez Díaz and financed by the Seventh Framework Program of the European Comission.

     The system removes particles, spores and small, noxious bacteria from the air in a few minutes, although in certain cases a catalyst must be added to neutralize the dangerousness of the suspended materials. According to Pérez Díaz, director of the master's degree in Fire Engineering and responsible for the research, "it's about minimizing the danger posed by agents in a dispersed state", substances that remain suspended in the air and have micrometric dimensions.

    The Counterfog manufactures a jet of mist in the form of tiny drops of water, of a size of microns, which collide with the harmful particles present in the air, add them and fall to the ground or adhere to the surfaces, where they can then be treated in a controlled manner. The researchers' work focused on how to "wash those particles". The problem was that by spraying the toxic cloud with water, the drops "slipped" between the particles of the pollutant, much smaller in size. That happens in fires, chemical leaks and biological and radioactive agents. In this way, experts at the University of Alcalála studied the ideal size of water droplets to "wash" the air of these pollutants. So they came to develop nozzles that create an artificial mist that serves to reduce the toxic cloud.


But, in addition, these nozzles are able to "absorb dirty air", whose waste falls to the ground, where it proceeds to decontamination without putting the population at risk, details the person in charge of the invention. To the fog you can add catalyst products, in cases of chemical and biological products, "that help break down the toxic particles".

Minimum waste
 
The Counterfog can also disperse other decontaminants and disinfectants, because the optimum size of the drops that it provides minimizes the volume of waste that is collected. According to those responsible for the development of the system, less than 1% of the additives used in the tests, always surrounded by a complex security system due to the dangerous nature of the particles, have proven to be sufficient to wash even the hydrophobic particles , those that they repel liquids.

As detailed by José Luis Pérez Díaz, the system "has proven to be respectful of the environment, both for harmless substances and for the minimization of waste". "Toxicity tests performed to date have not found significant damage in mice exposed to their action," he says. During his presentation, at the Torrejón Air Base, the simulation of a fire in a truck loaded with toxic products was simulated.

 The discharge of water used to control the emissions was infinitely less than the foam that is usually used in these accidents, whose remains created a white pool around the vehicle. In any case, the Counterfog is not the main element to attack a fire, since a very limited amount of water is used, but it is used in a manner associated with other means,

Therefore, this technological invention can also be used in buildings, hospitals, factories, industrial buildings, nuclear power plants and airports, as well as in sports stadiums, facilities in open spaces and hazardous materials deposits. In the event of a fire or a leak, the fog "in addition to cooling the area, also serves to create a curtain effect or barrier that contains both the toxic cloud and the advance of the flames."

As explained by the Captain of the Military Emergency Unit (UME), José María Martín Corrochano, the Counterfog "reduces the amount of water used, which also turns into contaminated waste, which is an undeniable benefit for the environment" .