Cometabolic biotransformation of trichloroethylene and chloroform by methanotrophs: Experimental studies and modeling of toxicity and sorption effects

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:7013577

Alvarez-Cohen, L

The goal of this research was to examine the cometabolic transformation of trichloroethylene (TCE) and chloroform (CF) by a mixed culture of methanotrophs in the absence of methane (resting cells), and to develop a model to describe the rate and extent of these reactions. TCE and CF transformations were initially fast, but decreased with time and eventually ceased altogether. Hence, the cells had a finite transformation capacity. A cometabolic transformation model which incorporates the effects of product toxicity and reductant supply into modified Monod kinetics was developed, and its applicability to methanotrophic TCE and CF transformation with and without formate addition was confirmed. Additionally, a competitive-inhibition modification of the model was applicable to the concurrent transformation of TCE and CF by resting cells. The rate and extent of TCE sorption onto a synthetic zeolite were measured, and the hypothesis that the contaminant transformation rate was proportional to solution concentration only and independent of the mass of compound sorbed was tested. Finally, a two-stage bioreactor was proposed for utilization of cometabolic biotransformations for the treatment of halogenated aliphatics, and the cometabolic biotransformation model used for optimization of the reactor design. For the treatment of TCE it was concluded that increasing methane and oxygen mass transfer rates, cell yield, and transformation capacity would have a greater impact on reducing overall reactor size than increasing the TCE transformation rate.

• Research Organization: Stanford Univ., CA (United States)
• OSTI ID: 7013577
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIODEGRADATION
BIOREACTORS
CHEMICAL REACTIONS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLOROFORM
DECOMPOSITION
HALOGENATED ALIPHATIC HYDROCARBONS
MATHEMATICAL MODELS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
SORPTION
TOXICITY