Surface-modified ceramic materials have been developed to disinfect water and air and other fluids without requiring additional chemicals or energy input. Developed by Claire Technologies (Raleigh, N.C.; www.claire-tech.com), the disinfection media consist of silica- and alumina-based pellets that have been modified to have powerful cationic surface sites. When they come into contact with microorganisms, the cationic sites at the ceramics’ surfaces pull electrons from the cells of the microbe, destroying them.
“The excellent germicidal properties of silver have been known for quite some time, but it has proven difficult to bring a silver-based disinfection system to industrial scale,” explains Cristian Chis, chief technology officer of Claire. “We have developed a process for coating the surface of the ceramic so that we can attach silver atoms covalently,” Chis says. In this way, the silver can kill microbes on contact, but does not leach out of the pellets.
In tests, the technology has demonstrated 5- to 10-log reductions in a wide range of bacteria, viruses, yeasts and micro-algae, including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Legionella adelaidensis and others.
Claire has built a production-scale facility for the disinfection media and is now testing its products for a host of applications, including wastewater disinfection, well water sanitation, drinking water disinfection, fighting Légionnaires infections, cooling-tower water disinfection, cooling oil disinfection, ballast-water treatment and others. In February 2015, Claire entered into a Cooperative Research and Development Agreement (CRADA) with the U.S. Environmental Protection Agency (www.epa.gov) involving wastewater and mobile emergency water-treatment systems.