| Abstract | A microcosm study was carried out to evaluate the potential for biodegradation of methyl tert-butyl ether (MTBE) impacting groundwater at a former oil refinery site located in Naples (SW Italy). A screening of aerobic, anaerobic and co-metabolic aerobic conditions was carried out by triplicate batch reactors, using
contaminated soil and groundwater from the study site. All microcosms were amended with ammonium
and phosphate salts and, if aerobic, they were supplied with excess oxygen throughout the static incubation
period of 6 months. Propane, pentane and n-hexane were selected as the primary substrates for cometabolic
treatments. After the initial lag phase (40-60 d), quantitative MTBE decay was repeatedly observed in the aerobic set amended only with nitrogen and phosphorus and further fed with MTBE, thus suggesting that the indigenous soil bacteria have the ability to degrade MTBE. All other treatments, i.e., anaerobic and co-metabolic aerobic, resulted unsuccessful after incubation extending up to 190 d. Bacterial consortia in the active microcosms were later enriched and further studied through second and third generation batch reactors with no soil, operated under continuous mixing for 5-7 months. MTBE degradation rate progressively increased with reactor operating time, following a zero order kinetics in the concentration range 1-10 mg L-1 and leading to a residual concentration of less than 10 ug L-1. The calculated maximum biodegradation rate was 20 mgMTBE gVSS -1 h-1. An accumulation of nitrite ions also occurred after long operating times, thus inhibiting MTBE degradation. This effect was minimized by replacing ammonium with nitrate. Identified degradation intermediates were tert-butyl alcohol and tert-butyl formate. Fluorescent in situ hybridization was applied for a preliminary microbiological screening of the consortia, suggesting that the detected cocci (about 0.5 and 1.5 lm diameter, respectively) and long bacilli with a narrow diameter might be as yet undescribed species. |
| Text | 181784 2009 10.1016/j.chemosphere.2008.12.053 ISI Web of Science WOS 000265159300003 MTBE Groundwater Microcosms In situ bioremediation Fluorescent In Situ Hybridization Enhanced bioremediation of methyl tert butyl ether MTBE by microbial consortia obtained from contaminated aquifer material Volpe A., Del Moro G., Rossetti S., Tandoi V., Lopez A. Volpe A.. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5, 70123 Bari, Italy Del Moro G. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5, 70123 Bari, Italy Rossetti S. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Area della Ricerca Roma 1 Montelibretti, Via Salaria km. 29.300, 00015 Monterotondo RM , Italy Tandoi V. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Area della Ricerca Roma 1 Montelibretti, Via Salaria km. 29.300, 00015 Monterotondo RM , Italy Lopez A. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5, 70123 Bari, Italy A microcosm study was carried out to evaluate the potential for biodegradation of methyl tert butyl ether MTBE impacting groundwater at a former oil refinery site located in Naples SW Italy . A screening of aerobic, anaerobic and co metabolic aerobic conditions was carried out by triplicate batch reactors, using contaminated soil and groundwater from the study site. All microcosms were amended with ammonium and phosphate salts and, if aerobic, they were supplied with excess oxygen throughout the static incubation period of 6 months. Propane, pentane and n hexane were selected as the primary substrates for cometabolic treatments. After the initial lag phase 40 60 d , quantitative MTBE decay was repeatedly observed in the aerobic set amended only with nitrogen and phosphorus and further fed with MTBE, thus suggesting that the indigenous soil bacteria have the ability to degrade MTBE. All other treatments, i.e., anaerobic and co metabolic aerobic, resulted unsuccessful after incubation extending up to 190 d. Bacterial consortia in the active microcosms were later enriched and further studied through second and third generation batch reactors with no soil, operated under continuous mixing for 5 7 months. MTBE degradation rate progressively increased with reactor operating time, following a zero order kinetics in the concentration range 1 10 mg L 1 and leading to a residual concentration of less than 10 ug L 1. The calculated maximum biodegradation rate was 20 mgMTBE gVSS 1 h 1. An accumulation of nitrite ions also occurred after long operating times, thus inhibiting MTBE degradation. This effect was minimized by replacing ammonium with nitrate. Identified degradation intermediates were tert butyl alcohol and tert butyl formate. Fluorescent in situ hybridization was applied for a preliminary microbiological screening of the consortia, suggesting that the detected cocci about 0.5 and 1.5 lm diameter, respectively and long bacilli with a narrow diameter might be as yet undescribed species. 75 Enhanced bioremediation of methyl tert butyl ether MTBE by microbial consortia obtained from contaminated aquifer material MTBE_Chemosphere_2009_DOI_10_1016j_chemosphere_2008_12_053.pdf Articolo in rivista Elsevier 0045 6535 Chemosphere Chemosphere Chemosphere Chemosphere. Chemosphere. Environmental chemistry, Chemosphere. Persistent organic pollutants and dioxins, Chemosphere. Environmental toxicology and risk assessment, Chemosphere. Science for Environmental toxicology, guido.delmoro DEL MORO GUIDO simona.rossetti ROSSETTI SIMONA angela.volpe VOLPE ANGELA antonio.lopez LOPEZ ANTONIO valter.tandoi TANDOI VALTER TA.P07.002.002 Sviluppo di nuovi processi di controllo dell inquinamento idrico. |
