Long-term aerobic cometabolism of a chlorinated solvent mixture by vinyl chloride-, methane- and propane-utilizing biomasses.
The aerobic cometabolic biodegradation of a mixture of chlorinated aliphatic hydrocarbons (CAHs) including vinyl chloride (VC), cis- and trans-1,2-dichloroethylene (cis-DCE, trans-DCE), trichloroethylene (TCE), 1,1,2-trichloroethane (1,1,2-TCA) and 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) was investigated at both 25 and 17 degrees C by means of bioaugmented and non-bioaugmented sediment-groundwater slurry microcosm tests. The goals of the study were (i) to study the long-term aerobic biodegradation of a CAH mixture including a high-chlorinated solvent (1,1,2,2-TeCA) generally considered non-biodegradable in aerobic conditions; (ii) to investigate the efficacy of bioaugmentation with two types of internal inocula obtained from the indigenous biomass of the studied site; (iii) to identify the CAH-degrading bacteria. VC, methane and propane were utilized as growth substrates. The non-bioaugmented microcosms were characterized, at 25 degrees C, by an average 18-day lag-time for the direct metabolism of VC (accompanied by the cometabolism of cis- and trans-DCE) and by long lag-times (36-264 days) for the onset of methane or propane utilization (associated with the cometabolism of the remaining CAHs). In the inoculated microcosms the lag-phases for the onset of growth substrate utilization and CAH cometabolism were significantly shorter (0-15 days at 25 degrees C). Biodegradation of the 6-CAH mixture was successfully continued for up to 410 days. The low-chlorinated solvents were characterized by higher depletion rates. The composition of the microbial consortium of a propane-utilizing microcosm was determined by 16s rDNA sequencing and phylotype analysis. To the best of our knowledge, this is the first study that documents the long-term aerobic biodegradation of 1,1,2,2-TeCA.
Frascari
Dario
D
Department of Chemical, Mining and Environmental Engineering, University of Bologna, Via Terracini 34, Bologna 40131, Italy. dario.frascari@unibo.it
Pinelli
Davide
D
Nocentini
Massimo
M
Zannoni
Arianna
A
Fedi
Stefano
S
Baleani
Emilia
E
Zannoni
Davide
D
Farneti
Angiolo
A
Battistelli
Alfredo
A
D000332:Aerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D015169:Colony Count, Microbial / Q000379:methods; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry / Q000378:metabolism*; D008697:Methane / Q000494:pharmacology*; D011407:Propane / Q000494:pharmacology*; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014752:Vinyl Chloride / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D006843:Hydrocarbons, Chlorinated; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D012997:Solvents; D014874:Water Pollutants, Chemical; D008697:Methane; D011407:Propane; D014752:Vinyl Chloride