PORTLAND, Ore. Cleansing biological contaminants such as anthrax from heating, ventilation and air conditioning (HVAC) ducts after a mail-borne attack like those leveled at U.S. Congressional office buildings can take months. Today's photocatalytic materials can neutralize biological materials in gas or liquid form, but much too slowly. What's worse, it's extremely difficult today to determine when a building is safe to reoccupy.
The 2008 Defense Department funding bill recently signed into law, however, aims to increase the efficiency of photocatalytics to more than 99 percent by funding a PhotoScrub prototype to be built by Nano-Proprietary Inc. (Austin, Texas) subsidiary Applied Nanotech Inc. (ANI). The $1.6 million project will result in a HVAC system prototype using PhotoScrub that cleanses 99 percent of anthrax and other biological contaminants in a single pass through an HVAC system, then gives an "all clear" signal when the building is safe to reoccupy.
"ANI will combine both sensor technology and PhotoScrub to increase the efficiency of the air cleaning with respect to biological threats and also give a measure of the degree of the cleaning that was performed in real time," said Zvi Yaniv, chief executive of ANI. "Today on the market one can find numerous air cleaners, but none of them also has the sensing technology for measuring the efficiency of the cleaning process. We also expect this application, which we are developing for national defense and homeland security, to eventually be transferred to higher-volume commercial applications."
PhotoScrub has already been proven out to the Defense Department by previous contracts that established the efficiency of the cleansing process in the lab. Now ANI will build a prototype based on a commercial HVAC system, plus design and install the sensors that measure success as the system is in operation.
How it works
PhotoScrub works by increasing the surface area of photocatalytic materials, which is layered down as a thin film coating on a flexible fiberglass cloth through which it blows contaminated air, decomposing the pollutants at the molecular level as they pass through.
Anthrax, even weaponized powder versions, were demonstrated to be eliminated at a rate of more than 99 percent per pass through a PhotoScrub treated filter. The system also removed other bacteria and viruses in a single pass, including Escherichia coli, MRSA (methicillin resistant staphylococcus aureus) and'influenza virus.