Biodegradation kinetics and microbial communities associated with methyl tert-butyl ether removal in a biotrickling filter

Abstract

A microbial culture capable of degrading methyl tertiary butyl ether (MTBE) was enriched in a laboratory-scale biotrickling filter. The reactor was continuously operated in a temperature-controlled condition for more than 100 days. Removal of MTBE vapors from air streams in a biotrickling filter was studied under various operating conditions, including the MTBE loading rate and the type of media in the circulating liquid. The changes in an MTBE-degrading bacterial community were investigated by using polymerase chain reaction (PCR) amplification of bacterial 16S rDNA. A subsequent analysis of the PCR products was performed by a single-strand-conformation polymorphism (SSCP) based on genetic profiles. Our results show that the MTBE removal efficiencies of 98.6–57.3% were observed at the MTBE loading rates of 2.67–50.76 g m −3 h −1 in the biotrickling filter. The removal efficiency appeared to increase by 27% (from 68 to 95%) in a later phase operation when the nitrogen source of (NH 4 ) 2 SO 4 was replaced by NaNO 3 . Due to the high MTBE loads in the inlet section, MTBE was removed mostly from the inlet section. The parameters estimated by using the Michaelis–Menten equation were 1.607 ± 0.208 ppmv s −1 for the maximum removal rate ( V m ), and 24.91 ± 0.794 ppmv for the half-saturation constant ( K s ). The total number of bands in an electrophoresis gel for various sections in the biotrickling filter using the same nitrogen source was similar, thus indicating similar compositions of species in the biotrickling filter. Nevertheless, communities grown in the presence of (NH 4 ) 2 SO 4 and NaNO 3 media exhibited a very different pattern, thus revealing a small change in community structure due to the type of media.