A team of environmental engineers have pioneered and tested a new technology using nanoparticles that can cleanse polluted underground aquifers that provide drinking water to an increasingly thirsty world.
‘Nanoparticles have been used in chemical processing and electrical engineering for years, but as far as I know, we are the first to use them for groundwater cleanup,’ said Wei-xian Zhang, associate professor of civil and environmental engineering at Lehigh University. ‘The potential of this technology to help improve the environment is enormous and truly has global implications.’
Nanotechnology involves pumping ‘nanoparticles’ into the groundwater. With a composition that is 99.9 percent iron and less than 0.1 percent palladium, nanoparticles reportedly have a large relative surface area and a high rate of reactivity.
When applied to water or soil contaminated with carcinogenic solvents used in dry cleaning and industrial processes, nanoparticles remove chlorine and convert the solvents to harmless hydrocarbons and chlorides commonly found in table salt. The approach is said to be more effective than traditional cleanup methods that require water to be pumped out, treated, then disposed of.
Nanoparticle technology reportedly offers the potential for significant savings. For example, a $20-million clean-up project might cost $5 million, said Zhang, and nationwide savings could be staggering considering that the US government alone projects spending $750 billion in the next 30 years to clean up contaminated groundwater.
The effectiveness of the new technology was demonstrated by the Trane Co. recently at its New Jersey manufacturing plant. Trane, a maker of air conditioning systems, has been investigating a toxic trichloroethene (TCE) plume for several years.
The company put nanoparticles to work in several monitoring wells. Samples taken from the wells 12 hours after the nanoparticles had been injected showed that as much as 96 percent of the TCE was reduced to harmless ethylene and ethane. Prior to that, the most effective method produced only a 25-percent reduction.
Lehigh’s researchers plan to test their remediation method this year at other contaminated groundwater sites, and are exploring the use of nanoparticles to neutralise explosives and treat nuclear waste sites.