In-Place Electrically Heated Regeneration of Vapor-Phase Activated Carbon.

The Air Force is using the air stripping process to remove a variety of volatile organic contaminants from groundwater. Vapor-phase granular activated carbon GAC has proven successful in treating the contaminated air stream emanating from air stripping columns. but conventional regeneration methods are expensive, require transfer of the carbon. and degrade the carbon. The objective of this experimental program was to determine the feasibility of using electrically-heated processes for the in-place regeneration of vapor-phase GAC. Two processes were considered, namely microwave heating and electric resistance heating using the carbon itself as the resistance. The microwave heating equipment used gave nonuniform heating over the length of the carbon column and was not pursued further. Electric resistance, or Rintoul, heating is a commercially proven process that has been applied to the high-temperature regeneration of liquid-phase GAC in special purpose furnaces. The experimental program demonstrated that the Rintoul process can be efficiently applied to low-temperature, low energy, in-place regeneration of vapor-phase GAO. Repeated loading and regeneration of the carbon column showed no loss of adsorption capacity. Two methods of collecting TCE in a concentrated form were also successfully tested. Both processes involved recovery of the TCE in a condensate. jg