Carbon tetrachloride degradation: Effect of microbial growth substrate and vitamin B{sub 12} content

• Published in: Environmental science & technology Vol. 34; no. 9
• Main Authors: Zou, S., Stensel, H.D., Ferguson, J.F.
• Format: Journal Article
• Language: English
• Published: United States 01.05.2000
• Subjects: AEROBIC CONDITIONS; ANAEROBIC CONDITIONS; BIODEGRADATION; CARBON TETRACHLORIDE; ENVIRONMENTAL SCIENCES; GROWTH; REMEDIAL ACTION; VITAMIN B-12
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es990930m

Microbial degradation kinetics of carbon tetrachloride (CT) under reducing conditions were investigated for different cultures, fed with 1,2-propanediol, dextrose, propionalde-hyde, or acetate and nitrate, in the anaerobic step of an anaerobic/aerobic operation sequence. Methanogenesis was inhibited due to the aerobic step. CT biodegradation rates followed first-order kinetics with respect to CT concentration and biomass and were not affected by the presence of growth substrate. CT degradation rates increased linearly with higher intracellular vitamin B{sub 12} content. The culture fed 1,2-propanediol had the highest vitamin B{sub 12} content, which was 3.8, 4.7, and 16 times that of the propionaldehyde-,dextrose-, and acetate-fed cultures, respectively, and its first-order degradation rate constant was 2.8, 4.5, 6.0 times that for those cultures, respectively. No CT degradation occurred with culture liquid, suggesting that intracellular factors were responsible for CT degradation. The propanediol culture was able to sustain a constant CT degradation rate for a 16-day test period without substrate addition. Compared to a propanediol-fed culture grown only under anaerobic conditions, the propanediol culture grown under the sequential anaerobic/aerobic condition resulted in more biomass growth and a greater CT degradation rate per unit of propanediol fed, although its CT degradation rate per unit of biomass was lower.