Nut Shells May Help Industry Stay Cleaner, Save Money

NEW ORLEANS, Oct. 11--What good are nut shells without nuts? They could be an ideal low-cost material for cleaning heavy metals out of industrial wastewater, a U.S. Department of Agriculture researcher says.

"We found a way to chemically treat pecan shells so they become activated charcoal filters, removing not only organic compounds from water, but also heavy metals," said chemist Chris Toles with USDA's Agricultural Research Service. "In tests, for example, the nutshell-based filters absorbed three times more copper than other types of filters currently on the market."

ARS chemist Wayne Marshall at the agency's Southern Regional Research Center in New Orleans added producing charcoals from nutshells might cut energy costs and provide a new market for a product that is typically considered waste.

"This could be a real opportunity for small nut producers who are willing to pool their resources," Marshall said.

Some industries, such as metal platers, would still need to filter wastewater with an ion exchange resin. But using the activated carbons as an inexpensive pre-filter could extend the life of the resin and reduce filtering costs.

The scientists have applied for a patent on the charcoal-making process, which involves treating the nut shells with oxidizing agents and heat.

A cooperative research and development agreement has been signed with Rio Grande Environmental Products, LLC, Albuquerque, N.M., a small business developed to commercialize environmental technologies. The firm intends to fund a prototype system to demonstrate the commercial viability of the carbons, according to company executive David Binkley.

Scientific contact: Wayne Marshall, Commodity Utilization Research Unit, ARS, USDA, Southern Regional Research Center, New Orleans, LA 70179; phone (504) 286-4356, fax (504) 286-4419.