Adsorption, desorption, and bioregeneration in an anaerobic, granular activated carbon reactor for the removal of phenol

Abstract

The use of anaerobic activated carbon filters to remove phe nolic compounds has been studied by a number of researchers.15 This treatment process combines the advantages of the energy efficient anaerobic filter and the adsorptive capability of activated carbon for extended retention of toxic or less readily biodegrad able compounds. Activated carbon protects microorganisms from shock loading through rapid initial adsorption into pores and slow subsequent release by desorption. This desorption phe nomena, accompanied by biod?gradation of the desorbed com pounds has been frequently referred to as bioregeneration. The evidence of this bioregeneration has been shown by many researchers. Chudyk and Snoeyink6 studied the interaction be tween biod?gradation and adsorption of phenol at low concen tration (1 mg/L) and suggested that significant bioregeneration of activated carbon occurred. While investigating continuous bioregeneration of granular activated carbon (GAC) during the anaerobic degradation of catechol, Suidan et al.1 noted that the carbon equivalent of the gaseous products (methane plus carbon dioxide in gaseous and aqueous phases) exceeded the organic carbon removed by the process and indicated that the extra gas eous products were the result of bioregeneration. Andrews and Trapasso8 showed that several compounds normally thought of as non-biodegradable (such as chloroform and chlorinated ben zene) were adsorbed on activated carbon and subsequently me tabolized by attached microorganisms. This indicated that the concept of bioregeneration could be applied to both readily bio degradable and toxic compounds. Andrews and Tien9 studied the bioregeneration of valeric acid in a fluidized-bed carbon re actor and detected a higher total carbon content in the effluent than in the influent.