Degradation and fate of carbon tetrachloride in unadapted methanogenic granular sludge

Journal Article · Wed Jul 01 04:00:00 UTC 1998 · Applied and Environmental Microbiology

OSTI ID:642317

Van Eekert, M H.A.; Schroeder, T J; Stams, A J.M.; Schraa, G; Field, J A ^[1]

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1. Wageningen Agricultural Univ. (Netherlands)

The potential of granular sludge from upflow anaerobic sludge blanket (UASB) reactors for bioremediation of chlorinated pollutants was evaluated by using carbon tetrachloride (CT) as a model compound. Granular sludges cultivated in UASB reactors on methanol, a volatile fatty acid mixture, or sucrose readily degraded CT supplied at a concentration of 1,500 nmol/batch without any prior exposure to organohalogens. The maximum degradation rate was 1.9 {micro}mol of CT g of volatile suspended solids{sup {minus}1} day{sup {minus}1}. The main end products of CT degradation were CO{sub 2} and Cl{sup {minus}}, and the yields of these end products were 44 and 68%, respectively, of the initial amounts of [{sup 14}C]CT and CT-Cl. Lower chlorinated methanes accumulated in minor amounts temporarily. Autoclaved (dead) sludges were capable of degrading CT at rates two- to threefold lower than those for living sludges, indicating that abiotic processes played an important role in the degradation observed. Reduced components in the autoclaved sludge were vital for CT degradation. A major part (51%) of the CT was converted abiotically to CS{sub 2}. The amount of CO{sub 2} produced was lower and the amount of Cl{sup {minus}} produced was slightly higher with autoclaved sludge than with living sludge. Both living and autoclaved sludges could degrade chloroform. However, only living sludge degraded dichloromethane and methylchloride. These results indicate that reductive dehalogenation, which was mediated better by living sludge than by autoclaved sludge, is only a minor pathway for CT degradation. The main pathway involves substitutive and oxidative dechlorination reactions that lead to the formation of CO{sub 2}. Granular sludge, therefore, has outstanding potential for gratuitous dechlorination of CT to safe end products.

• OSTI ID: 642317
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 7 Vol. 64; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BIODEGRADATION
BIOREACTORS
CARBON TETRACHLORIDE
CHLORINATED ALIPHATIC HYDROCARBONS
METHANE
METHANOGENIC BACTERIA
REMEDIAL ACTION
SLUDGES