Treatment of Methyl tert-Butyl Ether Vapors in Biotrickling Filters. 1. Reactor Startup, Steady-State Performance, and Culture Characteristics

An aerobic microbial consortium able to biodegrade methyl tert -butyl ether (MTBE) was enriched in two waste air biotrickling filters after continuous operation for 6 months. After this acclimation phase, the two laboratory-scale biotrickling filters were able to degrade up to 50 g of MTBE per cubic meter of reactor per hour, a value comparable to other gasoline constituents. Such high performance could be sustained for at least 4−6 weeks. After the acclimation phase, the MTBE degrading biotrickling filters were characterized by their almost full conversion (∼97%) of MTBE to carbon dioxide and the absence of any degradation byproducts in either the gas or the liquid phase. They also exhibited a very high specific degradation activity per amount of biomass (5−10 mg of MTBE per gram dry weight of cell per hour), and a low rate of biomass accumulation. An observed biomass yield of 0.1 g g - 1 and a specific growth rate of 0.025 day - 1 were determined for the biotrickling filter process culture. Further data on MTBE mass transfer and on the dynamic behavior of the biotrickling filter are presented in part 2 of this paper. Overall, the results demonstrate that MTBE can be effectively biodegraded under carefully controlled environmental conditions.