EFFECTS OF STIMULATOR SUBSTANCES ON AEROBIC METHYL TERT-BUTYL ETHER BIODEGRADATION BY MICROBIAL CONSORTIUM

Abstractin this study dissolved humic substances and yeast extract were tested in different concentrations for enhancing methyl tert-butyl ether mineralization by isolated microorganisms from a variety of sources. all experiments were conducted at a constant temperature of 25؛c. vials of 50 ml and 125 ml volume sealed with teflon-lined mini-nert caps was used for microcosm experiments. in all experiments 1% sodium azide were used as control. samples of bacterial cultures that metabolize methyl tert-butyl ether have been analysed by direct gc analysis using flame ionization detector. cultures able to metabolize have been found in activated sludge and soils. these microorganisms weregram-positive bacterium. an aerobic microbial consortium was enriched in laboratory for four months. methyl tert-butyl ether has been shown to biodegrade under aerobic and co-metabolic conditions. a microbial consortium isolated from activated sludges was identified as cocobacillus. the concentration of the initial attached biomass was about 0.11 g/l of dry weight. the maximum mineralization rate and beneficial effects of stimulator substances on aerobic biodegradation of methyl tert-butyl ether occurred with the culture by combined concentrations of 500 mg/l of yeast extract and 20 mg/l of peat humic growth support of microbial consortium within 216 h and in presence of high oxygen levels and well mixing conditions. it was shown that adding, peat humic and yeast extract together, had better stimulatory effect on methyl tert-butyl ether biodegradation. results clearly showed a stimulatory effect on methyl tert-butyl ether consumption higher than 20%. consortium was capable of degrading concentrations of =1000 mg/l, whereas concentrations of >1000 mg/l, were not degraded.