title: Aerobic/anaerobic/aerobic sequenced biodegradation of a mixture of chlorinated ethenes, ethanes and methanes in batch bioreactors.
abstract: A novel aerobic/anaerobic/aerobic treatment was implemented in batch reactors containing aquifer materials from a site contaminated by tetrachloroethylene (PCE), trichloroethylene (TCE), vinyl chloride (VC), 1,1,2-trichloroethane (1,1,2-TCA) and chloroform (CF). Consortia grown aerobically on methane, propane, n-pentane and n-hexane completely biodegraded the chlorinated solvent mixture, via aerobic cometabolism of VC, CF, TCE and 1,1,2-TCA, followed by PCE reductive dechlorination (RD) to 1,2-cis-dichlorothylene (cis-DCE) or TCE, and cis-DCE/TCE cometabolism in a further aerobic phase. n-Hexane was the best substrate. No electron donor was supplied for RD, which likely utilized cellular material produced during the aerobic phase. Chloride release was stoichiometric with chlorinated solvent biodegradation. According to the Lepidium sativum ecotoxicity test, a decreased toxicity was observed with propane, n-pentane and n-hexane, but not methane. A kinetic study of PCE RD allowed to estimate the PCE maximum specific rate (0.57 ± 0.07 mg mg(protein)(-1) day(-1)) and half-saturation constant (6.7 ± 1.5 mg L(-1)).
authors.affiliation: Department of Chemical, Mining and Environmental Engineering, University of Bologna, Via Terracini 28, 40131 Bologna, Italy. dario.frascari@unibo.it
authors.forename: Dario
authors.initials: D
authors.lastname: Frascari
authors.forename: Serena
authors.initials: S
authors.lastname: Fraraccio
authors.forename: Massimo
authors.initials: M
authors.lastname: Nocentini
authors.forename: Davide
authors.initials: D
authors.lastname: Pinelli
mesh_terms: D001420:Bacteria, Aerobic / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D061249:Batch Cell Culture Techniques / Q000295:instrumentation*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D045424:Complex Mixtures / Q000378:metabolism; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004980:Ethane / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*
chemical_list: D045424:Complex Mixtures; D005030:Ethylenes; D006843:Hydrocarbons, Chlorinated; D004980:Ethane; D008697:Methane