AEROBIC BIOLOGICAL REGENERATION OF DICHLOROMETHANE-LOADED ACTIVATED CARBON

A dichloromethane-degrading bacteria population is selected from sewage sludge. The microorganisms are employed in a fluidized-bed reactor for regeneration of dichloromethane-containing activated carbon. Bubble-free oxygenation of the reactor was executed by means of polydimethylsiloxane tubes. Three run modes of the reactor were investigated: (1) Aeration of dichloromethane-containing activated carbon without biomass; (2) treatment of the carbon with biomass and oxygenation by low gas flows of pure oxygen; and (3) biodegradation of the adsorbed dichloromethane under conditions of "dead-end" oxygenation, i.e., oxygenation via closed polydimethylsiloxane tubes and addition of pressure impulses of pure oxygen when the oxygen concentration in the reactor fell below 2 mg/L. The third mode was the most advantageous because no exhaust gas was produced and the dichloromethane was degraded totally to HCl and carbon dioxide. The bioregenerated activated carbon exhibited the same adsorption capacity as fresh, untreated activated carbon.