HIGH MTBE REMOVAL FROM A MICROBIAL CONSORTIUM ENRICHED AT AN ITALIAN NATIONAL INTEREST SITE

BTEX, MTBE, aliphatic and aromatic hydrocarbons are common groundwater contaminants, in areas where petrochemical activities have been carried out. A long term experimentation (18 months) has led to high rate MTBE removal bacterial cultures, developed in aerobic conditions without external carbon source addition, trough first, second and third generation aerobic microcosms, originally inoculated with the contaminated area subsoil. The Area is inside one of the 56 National Interest Site, contaminated for long time with BTEX and MTBE. MTBE degradation kinetic, in the third generation microcosms is 20 mg MTBE g-1 VSS h-1 (12-30 mg/L MTBE initial concentrations), with residual MTBE lower 10 ?g/L, that is the maximum limit for groundwater to be remediated according the Italian legislation. FISH was applied to reveal the microbial composition of the enrichment developed: the main biomass component is a large pale coccus (75% of DAPI positive micro-organisms). An in situ biological aerobic process, with nutrients and air addition can find application for the bioremediation of the site, stimulating the development of natural micro-organisms present at the contaminated Site.