CHARACTERISTICS OF ORGANICS REMOVAL BY PACT SIMULTANEOUS ADSORPTION AND BIODEGRADATION

The use of powdered activated carbon treatment (PACT), based on simult aneous adsorption and biodegradation, is effective for treating organi c toxic pollutants, present in industrial wastewaters. Removal of phen ol and aniline from aqueous solutions by biological treatment alone, b y adsorption on powdered activated carbon (PAC) alone and by simultane ous adsorption and biodegradation were compared. In the adsorption exp eriments, Langmuir adsorption isotherms were obtained, from which Q de grees, the limiting adsorption capacities, and b, the constant related to the energy of adsorption, were determined. Q degrees values of phe nol and aniline were found to be similar, while the energy-related con stant for aniline was five times higher than for phenol. Addition of m ineral nutrients, needed for the biological treatment, and inactivated microbial cells increased the limiting adsorption capacities and sign ificantly decreased the energy related constants. In biological treatm ent alone, kinetic studies showed that aniline was more resistant to b iodegradation than phenol. In the simultaneous adsorption and biodegra dation process, the PAC presence differently affected the biooxidation of phenol and aniline. While the PAC enhanced the microbial respirati on in the phenol bioreactor, it significantly reduced the microbial re spiration in the aniline bioreactor. Different organic removal mechani sms are suggested in PACT for phenol and aniline, due to their differe nt energy of adsorption. The respirometric studies are recommended as an adequate tool for prediction of toxic organics removal capabilities from industrial wastewaters by PACT. (C) 1997 Elsevier Science Ltd.