Continuous processing of toxic organics in a fluidized-bed GAC reactor employing carbon replacement

The fluidized-bed, granular activated carbon (GAC) anaerobic reactor has been shown to be an effective process for the continuous long-term treatment of wastewaters that contain biodegradable or nonbiodegradable toxic organic compounds. With loadings of 10 g COD/kg GAC day, COD removal of 94% was achieved. The anaerobic biofilm that develops on the GAC reduces the load on the carbon by converting the biodegradable organics to methane and carbon dioxide. Approximately 50% of the COD applied to the reactor was converted to methane, thereby reducing carbon requirements. Successful operation of the system requires that a carbon replacement schedule be maintained that will keep the bulk concentrations of toxic adsorbable compounds below their toxic threshold. As long as toxic substances can be adsorbed by the carbon, they will not inhibit the anaerobic biofilm. If nonadsorbable toxic compounds are present, processing must be included to reduce these materials to concentrations below their threshold level.