MTBE BIODEGRADATION IN AN INNOVATIVE BIOMASS CONCENTRATOR REACTOR: THE EVOLUTION FROM LABORATORY TO FIELD APPLICATION
The aerobic biodegradation of methyl tert-butyl ether (MTBE), a widely used fuel oxygenate, was investigated using an innovative pilot-scale biomass-retaining bioreactor called a Biomass Concentrator Reactor (BCR). The BCR was developed based on the porous pot reactor design that proved effective in remediating co-mingled groundwater contaminated with MTBE, gasoline hydrocarbons (benzene, toluene, ethyl benzene, and p-xylene), and several polycyclic aromatic hydrocarbons (PAHs). The BCR was operated for approximately five years treating flow rates as high as 5000 L/d of dechlorinated tap water spiked with MTBE alone, MTBE + BTEX, and MTBE + BTEX + other gasoline oxygenates (di-isopropyl ether, tert-amyl methyl ether, tert-amyl alcohol, and ethyl tert-butyl ether). The bioreactor affected excellent removal of all the aforementioned contaminants throughout the study, with effluent concentrations always lower than the 5 µg/L Drinking Water advisory set for MTBE in California. The BCR proved its resilience to fluctuations in environmental and substrate conditions. The field applicability of this novel design was then investigated with a full-scale BCR that was used to remediate groundwater contaminated with gasoline from a leaking underground storage tank in Pascoag, RI. The field BCR demonstrated its effectiveness at removing all the contaminants of concern (MTBE, BTEX, DIPE, TAME, TAA, tert-butyl alcohol, tert-butyl formate, methanol, and acetone) down to less than 5 µg/L. In addition, the reactor effluent was found to be of better quality than the influent groundwater as reflected from dissolved organic carbon analysis, a significant characteristic if the treated water were to be used for drinking purposes since it represents a significant reduction in trihalomethane (THM) precursors prior to disinfection. Molecular analysis of the microbial community populating the pilot- and field-scale bioreactors was performed using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction amplified 16s rDNA. Both reactors were found to be inhabited by a wide spectrum of bacterial species, most notably Hydrogenophaga flava and PM1 in the pilot BCR and Mycobacterium, Rhodococcus, and Sphingobacterium species in the field BCR.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:biodegradation mtbe btex oxygenates membrane bioreactor bcr
Date of Publication:01/01/2006