| heal.abstract |
Biofiltration is a microbial treatment technology used for the elimination of contaminants from gaseous and liquid effluents, in which pollutants are transferred to the solid matrix of the biofilter, where microorganisms metabolize them to CO 2, H 2O, or intermediates. Industrial emissions commonly contain compound mixtures (e.g., CH 3OH and H 2S in the pulp and paper industry) that are structurally different, requiring a diverse microbial community for complete degradation, and results in removal kinetics different from those of single-compound studies. This article describes changes in the bacterial community of a compost biofilter measured using 16S rRNA genes cloned from the biofilter and the impact of the presence of methanol (CH 3OH) on degradation kinetics of hydrogen sulfide (H 2S). Before H 2S addition, the initial bacterial community in the biofilter was characterized by high diversity (Shannon Weaver index, H = 3.65), species richness (richness index, d = 23.94), and evenness. After 20 days of acclimatization to H 2S, ribotypes related to the sulfur-oxidizing bacteria Thiobacillus and Sulfobacillus dominated, resulting in lower diversity and richness (H = 1.33, d = 2.77). Introduction of CH 3OH resulted in the enrichment of a variety of CH 3OH and H 2S degraders, thus enhancing the bacterial community (H = 3.02, d = 15.10). Comparison of the mean first-order rate constant for degradation of H 2S showed that the rate constant was significantly higher (t-test, p-value = 0.002) with CH 3OH introduction (0.040 ± 0.011 s -1) than without (0.022 ± 0.009 s -1). These results indicate that introduction of a co-metabolic substrate enhances bacterial diversity, potentially leading to increased degradation of target compounds. This approach to biostimulation warrants further investigation to identify other non-toxic, easily available stimulants that could be used to improve biofilter performance. © 2006 American Society of Agricultural and Biological Engineers. |
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