Influence of metabolic activity on biosorption of halogenated aromatics by anaerobic granules

Abstract

Equilibrium sorption isotherms and sorption kinetics of 2,4‐dichlorophenol (2,4‐DCP) and 2,3,6‐trichlorophenol (2,3,6‐TCP) on live metabolically dormant, live metabolically active, and chemically inactivated anaerobic granules were investigated using batch serum bottle tests. Two metabolic inhibitors, sodium azide (NaN₃) and bromoethane‐sulfonic acid (BESA), were used. Sodium azide was used to specifically inactivate the metabolic activity of the three microbial consortia (hy‐drolytic, acidogenic, and methanogenic bacteria), and BESA was used to specifically inactivate the metabolic activity of the methanogenic bacteria. The sorption of 2,4‐DCP and 2,3,6‐TCP by anaerobic granules was a rapid process, reaching equilibrium in approximately five hours. Experimental results show insignificant difference in the biosorption of live metabolically dormant bacteria (control 1) that make up the whole anaerobic microbial consortia, metabolically dormant hydrolytic and acidogenic bacteria with chemically inactivated methanogens (BESA‐D), metabolically active hydrolytic and acidogenic bacteria with chemically inactivated methanogens (BESA‐A), chemically inactivated hydrolytic, acidogenic, and methanogenic bacteria (NaN3‐I) and live metabolically active anaerobic granule consortia (control 2). Biosorption isotherms for 2,4‐DCP and 2,3,6‐TCP using live metabolically dormant, chemically inhibited (BESA‐A, BESA‐D, NaN₃‐I) and live metabolically active biomass fit very well the linear and Freundlich equations, respectively. No large difference in the ? and 1/n constants for the different sludge conditions was observed. Experimental findings indicate that anaerobic biosorption for all three anaerobic microbial groups in the consortia is largely a physical‐chemical process that is relatively unaffected by microbial metabolic activity.

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