AbstractA comparison was made between biological and chemical mineralization of pyridine, anN‐heterocyclic pollutant, in a liquid culture and a slurry of ground water and subsurface sediment. A bacterial culture of anAlcaligenessp. that degrades pyridine was found to be more effective at oxidizing 2,6‐14Cpyridine to14CO2than Fenton's reagent.Alcaligenessp. converted 73.1 of the14C‐labeled pyridine to14CO2, whereas the Fenton reagent converted 65.6 of the compound. In the case of bacteria, the remaining chemical was incorporated primarily into biomass (9.2), whereas the remaining pyridine was converted to unidentified products (16.3) by the Fenton reagent. However, based on chromatographic analysis, these compounds were not mono‐hydroxylated pyridines. Mineralization of pyridine by Fenton's reagent was affected by the concentration of H2O2and by the concentration and oxidation state of available iron. Maximal mineralization occurred at a concentration of more than 0.15 H2O2(44 mM), 1 mM Fe3+, or 2 mM Fe2+. Furthermore, the rates of both microbial and chemical mineralization were influenced by the initial pyridine concentration. Maximum specific rates of mineralization were 6.5 μg/h/mg biomass for the bacteria and 2.7 μg/h/mg Fe2+for the Fenton reagent. The feasibility of using Fenton's reagent for treating ground water and subsurface sediments polluted with pyridine was found to be limited, because only 24.5 of the pyridine was converted to CO2. In contrast, when cultures of theAlcaligenessp. were used to treat ground water, as much as 54.4 of the labeled compound was mineralize
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