MICROBIAL-DEGRADATION OF AROMATIC AND POLYAROMATIC TOXIC COMPOUNDS ADSORBED ON POWDERED ACTIVATED CARBON

The microbial degradation of phenol (300-1300 mg l(-1)), p-nitrophenol (50-500 mg l(-1)), and phenanthrene (50-300 mg l(-1)) adsorbed on pow dered activated carbon (PAC) was studied. The combination of physical sorption and biological degradation on PAC, which serves as adsorbent carrier, was compared with the degradation performance of suspended ce lls and cultures attached to sand, which serves as an example of an in ert support. Almost similar profiles of degradation were obtained in t he cultures with PAC for the three compounds studied, over the entire concentration range. However, at the higher concentrations, degradatio n was dramatically inhibited, or even ceased completely, in suspended or sand-attached cultures, even though specialized mixed bacterial cul tures adapted to high toxicant concentrations were used in each case. Degradation with PAC assumes an intrinsic relationship between the act ivated carbon and bacteria in the same environment, thus regenerating the surface of the adsorbent/carrier as diffusion and degradation proc eed. The adsorbed material desorbs, diffuses out of the carbon and can then be metabolized. Our results highlight the applicability of activ ated carbon, in either powdered or granular form, to achieve a steady- state operation in continuous process, fdr the treatment of toxic chem icals, even with specialized bacteria. Copyright (C) 1996 Elsevier Sci ence B.V.