Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
The present invention relates to a bioreactor
for the biochemical treatment of liquids containing
organic matter.
BACKGROUND OF THE INVENTION
A bioreactor for such treatment of liquids is
described in United States patent 4,654,308 issued
March 31, 1987 to Safi et al. This patent describes
the need to treat liquids containing organic matter,
such as in the pulp and paper industry or the cheese
processing industry due to pollution regulations
imposed by governments.
When a substrate, during anaerobic treatment,
comes into contact with microorganisms, it is converted
into gas by means of two principal reactions which
occur in sequence.
The first reaction to occur, known as
acidogenesis reaction, is when the substrate is
converted to volatile acids due to the action of the
acidogenesis microorganisms. In this reaction, the
rate of conversion into acids of the substrate is
proportional to the concentration of the substrate.
The second reaction, known as methanogenesis
reaction, occurs when the volatile acids, through the
action of methanogenesis micro-organisms, are converted
into methane (biogas). In this reaction, the rate of
conversion of the volatile acids into methane is
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inversely proportionate to the concentration of
volatile acids.
In general, both described reactions occur
sequentially in the same reactor.
The bioreactor defined in the above mentioned
U.S. patent consists of a tubular container with a
plurality of spaced apart trays, each tray being
apertured to provide liquid flow communication between
the inlet and outlet with apertures of alternate trays
being arranged relative to one another to cause the
liquid to flow laterally across the respective cell
beds of the trays as the liquid flows from one tray to
another. It has been found, however, that there is a
possibility for the fluid and the microorganism cells
to return to the lower compartment, thus greatly
reducing the efficiency of the reactor.
OBJECTS AND STATEMENT OF THE INVENTION
It is an object of the present invention to
provide a flow reactor which overcomes the above
described problem associated with presently known
bioreactors.
The present invention relates to a bioreactor
for the biochemical treatment of liquids containing
organic matter which comprises:
- an upstanding container having inlet means
for receiving liquids to be treated and outlet means
for discharging liquids once treated;
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- plate means in the container defining, on
either side of the plate means, upper and lower
compartments;
- a bed of microorganism cells supported on
the plate means in the upper compartment, the cells
being capable of reacting with the organic matter to
form a volatile gas; the plate means having aperture
means therethrough to provide liquid flow communication
between the upper and lower compartments;
- blockage means in the upper compartment,
associated with the aperture, for preventing the liquid
and microorganism cells from returning through the
aperture means to the lower compartment; and
- means for releasing the gas from the
container.
According to a preferred embodiment of the
invention, the blockage means comprise a tubular
portion extending upwardly from the aperture means and
a cap portion extending above the open end of the
tubular portion. The area between the cap portion and
the tubular portion is filled with part of the gas
formed by the reaction of the cells with the organic
matter, this gas-filled area acting as a stopper to
prevent the return of the liquid, cells and gas in the
adjacent lower compartment.
According to another preferred embodiment,
baffle means are mounted under the plate means in the
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area of the aperture means to improve the hydrology of
the reactor.
- Other objects and further scope of
applicability of the present invention will become more
readily apparent from the following description of
preferred embodiments. It should be understood,
however, that this detailed description, while
indicating preferred embodiments is given by way of
illustration only, since various changes and
modifications within the spirit and scope of the
invention will become apparent to those skilled in the
art.
- BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic longitudinal
sectional view of a bioreactor according to the present
invention;
Figures 2, 3 and 4 are top plan views of
three embodiments of blockage means used with the
present invention;
Figures 5, 6 and 7 are elevational views of
the blockage means illustrated in Figures 2, 3 and 4
respectively;
Figure 8 is a cross-sectional view of another
embodiement of the blockage means;
Figures 9 and 9a are top and elevational
views of another embodiment of the blockage means;
Figure 10 is a cross-sectional elevation of
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blockage and baffle means used with the present
invention;
Figure 11 is a bottom plan view of that
illustrated in Figure 10;
Figure 12 is a cross-sectional elevation
illustrating another embodiment of baffle means used
with the present invention; and
Figure 13 is a bottom plan view of the
embodiment illustrated in Figure 12;
Figure 14 shows an elevational view of
another embodiment of a reactor made in accordance with
the present invention;
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figure 1, there is shown
schematically a bioreactor 10 for the biochemical
treatment of liquids containing organic matter. An
inlet line 12 allows the liquids to be received at the
bottom of the container. The container comprises an
intermediate horizontal plate 14 having a central
aperture 16. A bed 18 of microorganism cells is
supported on the plate.
The plate 14 divides the container 10 into
two compartments 20 and 22. In the upper compartment
22, a first outlet 24 is provided for discharging
treated liquid while a second outlet 26 is used for
discharging the volatile gas which is formed by the
reaction of the liquid with the microorganism cells.
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According to the present invention, a
blockage element, generally denoted 28, is provided
over aperture 16 of the plate and comprises a tubular
portion 30 extending upwardly from the aperture 16 and
a cap portion 32 extending over the tubular portion 30
and supported thereto by means of three arms 31.
Preferably, the container 10 comprises also a
bed of microorganism cells 34 resting on the bottom
wall 36 of the container 10.
The reactor shown in Figure 1 functions in
the following manner. The liquid to be treated enters
the container 10 via inlet 12 and reacts with the
microorganism cells of the bed 34 of the lower
compartment 20. Continuous flow of liquid in the
container causes the treated liquid and the gas formed
by the reaction to pass to the upper compartment 22
through aperture 16 where the liquid again reacts with
the second bed 18 of microorganism cells. The liquid
thus treated exits at outlet 24 while the volatile gas
exits at outlet 26.
The blockage element 28 acts as a "check
valve" to prevent the liquid and the microorganism
cells in the upper compartment to return to the lower
compartment 20 through the aperture. The area situated
under the cap portion 32 is filled with gas resulting
from the reaction of the first cell bed 34 with the
liquids.
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Figures 2, 3 and 4 show various shapes of
blockage elements 28a, 28b, 28c which may be used with
the present invention. In Figure 2, the blockage
element takes the shape of an inverted cup member 32a
while the blockage element of Figures 3 and 4, 32b and
32c are respectively square and rectangular shaped
inverted bodies.
The blockage element 28d of figure 8 takes
the form of an inverted U-shaped tubular member 40
while, in Figure 9, the blockage element has a T-shape
with opposite branches 42a and 42b.
Referring to Figures 10 and 11, the hydrology
between adjacent compartments may be improved by
disposing, under the plate, a plurality of baffle
means. In the embodiment illustrated in these figures,
plate 44 displays a series of apertures 46, each
receiving thereover a blockage element 48 situated in
the upper compartment of a container. In the lower
compartment, underneath plate 44, a plurality of baffle
members 56 in the shape of cylindrical bodies have a
lower opening 58 in registry with aperture 46. These
baffle members may have various shapes.
Figures 12 and 13 show another embodiment of
baffle members used with the present invention. The
plate 60 of the reactor includes a plurality of
blockage elements 64 extending in the upper compartment
while, in the lower compartment, a baffle member
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extends under the full area of the plate and includes a
matrix of dividing walls 70, 72, 74, 76 and a bottom
wall 78 with an opening 80 in each compartment formed
by the matrix.
Figure 14 shows another variation of a
bioreactor made in accordance with the present
invention. Body 100 of the container has an inlet 102
for the liquid to be treated and a series of vertically
spaced compartments 104, 106, 108 and 110, each
including a bed of microorganism cells and blockage
means as described above. However, in the present
embodiment, a series of outlets 112, 114, 116 and 118
are provided for the outlet of the volatile gas from
each compartment.
Although the invention has been described
above with respect to various forms of the invention,
it will be evident that it may be modified and varied
in various ways. For example, there may be provided a
liquid inlet for each-compartment rather than a single
inlet at the bottom as illustrated. Further, these
inlets may enter each compartment in the bed of
microorganism cells or thereabove. It is therefore
wished to have it understood that the present invention
should not be limited in interpretation except by the
terms of the following claims.
