제  목 : Microwave Remediation Technology Is as Good as Gold
  일  자 : 1998년 07월
  제공처 : Internet

     Microwave Remediation Technology Is as Good as Gold
     ===================================================

                                              Technology in the News

   New Orleans ？When you？re done heating your frozen dinner in the
   microwave, engineers may want to use it to decontaminate hazardous
   waste.

   Well, not quite, but microwave technology similar to that used in home
   units has been successfully tested in remediating a variety of hazardous
   wastes.

   ？Microwave technology, often in combination with vitrification, has
   proven effective in treating a wide range of radioactive wastes and
   other potentially hazardous materials, including contaminated soils and
   sediments, incinerator ashes, industrial wastes, rubber products and
   tires, medical and infectious wastes, weapons components, volatile
   organic compounds, and discarded electronic circuitry,？ said George
   Wicks, a senior advisory scientist with Westinghouse Savannah River
   Company in Aiken, South Carolina. Wicks discussed the patented
   technology at the American Institute of Chemical Engineers？
   (AIChE？s) 1998 Spring National Meeting in New Orleans.

   The need to treat hazardous wastes has increased over the years as
   more products containing hazardous components enter the waste
   stream and are discarded in landfills, many of which are now reaching
   capacity. The scope of these wastes has expanded from industrial and
   radioactive wastes to include an ever-increasing inventory of seemingly
   innocuous consumer wastes, including the electronic components and
   circuits used in a variety of discarded high-tech systems such as
   computers, automotive systems, medical life-support systems,
   televisions, telephones, refrigerators, and a multitude of other consumer
   goods. Not only are a variety of hazardous materials often contained
   within these electronic components, they can leach from the waste and
   contaminate groundwater. And, because they are thrown away, the
   natural resources in these wastes, including precious metals, cannot be
   recycled or reused.

   Thermal decontamination of hazardous waste is not a new
   concept？electrical heat already has proven successful in certain
   applications. But, microwave technology offers expanded options at a
   reduced cost. ？By using microwave energy to carry out vitrification, a
   process in which waste is molecularly bonded in glass, we are able to
   improve conventional microwave technology to process an even larger
   variety of industrial and consumer wastes, as well as reclaim metals for
   reuse,？ said Wicks. ？Among the advantages are a significant reduction
   of waste volume and the ability to separate important metal
   components,？ he added. In fact, Wicks reports, as much as 99 percent
   of the gold and other precious metals in discarded electronic
   components are recovered.

   The technology was developed by a partnership between Westinghouse
   Savannah River and the University of Florida. The team includes
   Wicks, and from the University of Florida, professor David Clark and
   graduate student Rebecca Schultz. In lab tests, a wide array of
   electronic components were successfully treated by a relatively simple,
   one-step, hybrid-heated microwave process.

   To remediate the waste, the researchers used tandem microwave units
   to heat the material and destroy both the primary and secondary wastes
   in small, portable, self-contained units. After destroying the solid and
   liquid wastes in the main chamber, the ？off gases？ are transferred to the
   second unit that decomposes the hazardous compounds.

   Although the process is still lab scale, with the microwave units ranging
   in size from a home unit to one the size of a refrigerator, Wicks said
   that it can be mocked-up to a larger scale and can be made both
   remotable and mobile. ？Also, by using a conveyor system, we can take
   it from a batch process to continuous process, if desired,？ he said.

   Wicks noted that the process still may be three to five years away from
   large-scale commercial applications, depending on support. He added
   that its initial uses will likely be in remediating medical waste, which
   pose a more immediate concern in the United States. Wicks added that
   microwave treatment of rubber tires also shows promise for early
   applications.