United States
Environmental Protection
Agency
EPA/540/F-93/506
July 1993
vvEPA
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Methanotrophic Bioreactor System
BiotroP, Inc.
Technology Description: BioTrol's Methanotrophic Bioreactor
is an above-ground remedial system for water contaminated with
halogenated volatile organic compounds, including trichloroethyl-
ene (ICE) and related chemicals. Its design features circumvent
problems peculiar to treatment of this unique class of chemicals.
First, microorganisms are not known which utilize these chemi-
cals as a primary carbon source; so a specific organism
(Methylosinus trichosporium OB3b, or simply OB3b) is used which
oxidizes these compounds rapidly while utilizing methane, an
abundant and inexpensive source of carbon, as its growth sub-
strate. Second, because of the ability of the bacterium to degrade
ICE in the absence of the growth substrate, growth of the
organism and degradation of the contaminants can take place in
separate reactor vessels. This is important because these con-
taminants are extremely volatile, and bubbling of methane or air
through the reaction vessel would likely result in stripping of the
contaminants from the water.
A two-stage bioreactor system (diagramed in Figure 1) was
designed which circumvents these problems. The first stage
involves the propagation of OB3b on methane in a continuous-
flow suspended growth reactor (culture vessel). Cells grown in
the culture vessel are supplied to the second stage (plug flow)
contactor where the culture medium is mixed with the contami-
nated water.
For the pilot demonstration, the culture vessel consisted of a 400-
L fermenter which was modified to permit continuous-flow fer-
mentation and the use of methane as the growth substrate.
Methane transfer efficiency to the culture vessel was improved by
addition of a circulating gas-saturation device. The plug flow
Ground
Water
IPlug Flow
Contactor
v
Effluent
Figure 1. Bioreactor system flow diagram.
Printed on Recycled Paper
-------
United States
Environmental Protection
Agency
EPA/540/F-93/506
July 1993
v>EPA
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Methanotrophic Bioreactor System
BiotroP, Inc.
Technology Description: BioTrol's Methanotrophic Bioreactor
is an above-ground remedial system for water contaminated with
halogenated volatile organic compounds, including trichloroethyl-
ene (ICE) and related chemicals. Its design features circumvent
problems peculiar to treatment of this unique class of chemicals.
First, microorganisms are not known which utilize these chemi-
cals as a primary carbon source; so a specific organism
(Methylosinus trichosporium OB3b, or simply OB3b) is used which
oxidizes these compounds rapidly while utilizing methane, an
abundant and inexpensive source of carbon, as its growth sub-
strate. Second, because of the ability of the bacterium to degrade
ICE in the absence of the growth substrate, growth of the
organism and degradation of the contaminants can take place in
separate reactor vessels. This is important because these con-
taminants are extremely volatile, and bubbling of methane or air
through the reaction vessel would likely result in stripping of the
contaminants from the water.
A two-stage bioreactor system (diagramed in Figure 1) was
designed which circumvents these problems. The first stage
involves the propagation of OB3b on methane in a continuous-
flow suspended growth reactor (culture vessel). Cells grown in
the culture vessel are supplied to the second stage (plug flow)
contactor where the culture medium is mixed with the contami-
nated water.
For the pilot demonstration, the culture vessel consisted of a 400-
L fermenter which was modified to permit continuous-flow fer-
mentation and the use of methane as the growth substrate.
Methane transfer efficiency to the culture vessel was improved by
addition of a circulating gas-saturation device. The plug flow
IPlug Flow
Contactor
v
Effluent
Figure 1. Bioreactor system flow diagram.
Printed on Recycled Paper
------- |