ISSN:
0006-3592
Keywords:
cometabolism
;
methanotroph
;
trichloroethylene
;
reactor
;
aerobic
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The objective of this research was to evaluate several factors affecting the performance of a two-stage treatment system employing methane-oxidizing bacteria for trichloroethylene (TCE) biodegradation. The system consists of a completely mixed growth reactor and a plug-flow transformation reactor in which the TCE is cometabolized. Laboratory studies were conducted with continuous growth reactors and batch experiments simulating transformation reactor conditions. Performance was characterized in terms of TCE transformation capacity (TC, g TCE/g cells), transformation yield (TY, g TCE/g CH4), and the rate coefficient ratio kTCE/KS,TCE (L/mg-d). The growth reactor variables studied were solids retention time (SRT) and nutrient nitrogen (N) concentration. Formate and methane were evaluated as potential transformation reactor amendments. Comparison of cultures from 2- and 8-day SRT (nitrogen-limited) growth reactors indicated that there was no significant effect of growth reactor SRT or nitrogen availability on TC or TY, but N-limited conditions yielded higher kTCE/KS,TCE. The TCE cometabolic activity of the 8-day SRT, N-limited growth reactor culture varied significantly during a 7-year period of operation. The TC and TY of the resting cells increased gradually to levels a factor of 2 higher than the initial values. The reasons for this increase are unknown. Formate addition to the transformation reactor gave higher TC and TY for 2-day SRT growth reactor conditions and significantly lower TC, TY, and kTCE/KS,TCE for 8-day SRT N-limited conditions. Methane addition to the transformation reactor inhibited TCE cometabolism at low TCE concentrations and enhanced TCE cometabolism at high TCE concentrations, indicating that the TCE cometabolism in the presence of methane does not follow simple competitive inhibition kinetics. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 650-659, 1997.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
