Bioregeneration of activated carbons by bacterial degraders after adsorption of surfactants from aqueous solutions

The feasibility of activated carbon (AC) bioregeneration after adsorption of biologically resistant surface-active substances (SAS) by a community of strains of SAS-degrading bacteria of the genus Pseudomonas are analyzed. It was shown that the degree of AC equilibrium saturated with nonionic SAS under static conditions was 23-35%. The contribution of bacterial destruction of SAS to the restored capacity was 20-23% and, for all practical purposes, did not depend on the AC porosity. The efficiency of regeneration of the microporous AC after adsorption by it of the nonionic and anionic SAS under dynamic conditions was 22 and 95% of the respective capacities of fresh samples. The extent of regeneration of the mesoporous AC after dynamic sorption of nonionic SAS was 85%. Results indicate that regeneration is based on desorptive and migrational movements of the adsorbate toward the biocenosis of SAS-degrading bacteria located on the external surface of the AC grain. The adsorptive properties of the AC-SAS system and the sorbents' porous structure determine the probability of desorption of molecules and the rate of their diffusion into the peripheral zone of the grain. The AC regeneration efficiency depends on the nature of the adsorbate distribution in its porous structure. (C) 2003 Elsevier B.V. All rights reserved.