CHARACTERIZATION AND DEGRADATION KINETICS OF AEROBIC MTBE DEGRADING CULTURES

摘要

This study examines the effect of alternative substrate on the kinetics of methyl tert-butyl ether (MTBE) degradation. Four cultures were studied, each enriched under the following substrate conditions: MTBE with ethanol (EtOH), MTBE with diethyl ether (DEE), MTBE with diisopropyl ether (DIPE) and MTBE alone. Batch degradation experiments were carried out with each culture for both MTBE and tert-butyl alcohol (TBA), a key degradation intermediate of MTBE. A range of three initial concentrations (0.07 mM, 0.20 mM and 0.50 mM) were studied, with and without the addition of equivalent chemical oxygen demand (COD) of the alternative substrate. Each culture produced a unique degradation rate curve for MTBE, TBA, and overall degradation. The highest rates of degradation were observed in the MTBE only culture. The lowest rates of degradation were observed in the DIPE culture. The presence of an alternative substrate had an effect of slowing the rates of MTBE and TBA degradation, except in the case of DIPE, where it was observed to enhance the MTBE to TBA conversion step, but still slowed the overall degradation rate. Denaturing gradient gel electrophoresis (DGGE) was performed on all cultures and served in identifying the bacterial composition of the cultures, providing some explanation of the kinetic similarities and differences observed among the cultures.