Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A TREATMENT UNIT FOR TREATING A FLUID
AND METHOD THEREOF
FIELD OF THE INVENTION
The present invention generally relates to the field of fluid treatment. More
specifically, it is directed to a treatment unit for treating a fluid in
continuous. The
treatment unit may advantageously be used for the removal of a substrate
contained
in a fluid either by its capture or by its biological transformation.
BACKGROUND OF THE INVENTION
Already known in the art and especially in the industries or the
research/analysis
laboratories, are treatment units for treating a fluid which generally operate
either in
batch or continuously. Very few of those units rely on the principle of
baffles when
enzymatic treatment or any other biological treatment are involved.
Overall, treatment units of the art often use, as reactive materials, enzymes
or
microorganisms confined, for instance, in a gel or held at the surface or
incorporated
to a membrane. Examples of such treatment units are shown in US patents nos.
5,057,421 and 5,772,887.
While the treatment units known in the art have resulted to the advancement
within
the present field, an important problem in this area continues to persist.
This problem
arises from the fact that the treatment units known in the art do not allow
the removal
of the reactive material support during the treatment process, and furthermore
they
do not provide the opportunity to carry out simultaneously the enzymatic
transformation and the capture of a fluid element. Therefore, an interruption
of the
treatment process, for instance, after the saturation of the membranes or the
weakening of the reactive material activity, leads to operation procedures
which are
very long and by the same token very expensive.
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SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a treatment unit
for
treating a fluid that will overcome these drawbacks.
In accordance with the present invention, that object is achieved with a
treatment unit
for treating a fluid in continuous. The unit comprises a reservoir which
includes a fluid
inlet for receiving a fluid to be treated and a fluid outlet for releasing a
treated fluid,
whereby a fluid in the reservoir is flowing from the fluid inlet towards the
fluid outlet.
The unit also comprises at least one cassette provided with a reactive
material for
treating the fluid and at least two spaced-apart baffle walls in the reservoir
for
regulating the flow of the fluid therein. A reaction chamber having an opening
for
removably inserting therein one of the at least one cassette is defined
between each
of the at least two spaced-apart baffle walls. Yet, the unit further comprises
mounting
means for mounting the at least one cassette in a reaction chamber spaced-
apart
from the two baffle walls, whereby a cassette being disposed between two
spaced-
apart baffle walls causes the fluid to flow in a zigzag pattern thus further
regulating
the flow of the fluid.
The present invention is also directed to a combination of a treatment unit as
defined
above with a similar treatment unit. The combination comprises connecting
means
for connecting the treatment units together.
The present invention also proposes a method for treating a fluid in
continuous. The
method comprises the steps of:
a) providing a treatment unit as defined above;
b) inserting in the reaction chamber defined between each of the at least two
spaced-apart baffle walls a cassette provided with a reactive material;
c) mounting the cassette in the reaction chamber spaced-apart from the baffle
walls and thereby defining a zigzag path between the baffle walls and the
cassette
for a flow of fluid flowing across the reservoir; and
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d) continuously supplying the reservoir of the treatment unit with a fluid to
be
treated and containing a substrate, thereby causing the fluid to flow across
the
reaction chamber following the zigzag path and wherein the substrate
reactswith the
reactive material of the cassette, and then towards the fluid outlet to
release a
treated fluid.
A treatment unit according to the present invention proposes innovative
features that
makes it an economical tool for research or industrial applications. As a
matter of
fact, because of the versatility of such treatment unit, it becomes easy to
biotransform a substrate, as well as to capture a proteinic element contained
in a
fluid. Furthermore, the treatment unit allows the simultaneous use of
different kinds
of cassette such as a dialysis cassette and those having at their surface an
immobilisation support to which is coupled a reactive material. Moreover, the
treatment unit of the present invention proposes the use of removable
cassettes
which impart to this invention an advantageous multifunctional feature.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention and its advantages will be more easily understood after
reading the following non-restrictive description of a preferred embodiment
thereof,
made with reference to the following drawings wherein:
Figure 1 is an exploded perspective view of a treatment unit according to a
first
preferred embodiment of the invention, with one side wall removed to better
see the
inside of the treatment unit.
Figure 2 is a cross-sectional side view of a portion of the treatment unit of
Figure 1,
illustrating a flow of a fluid across two reaction chambers.
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Figure 3 is a cross-sectional side view of a treatment unit according to a
second
preferred embodiment of the invention, wherein a biocatalytic bed is used as a
support member.
Figure 4 is a cross-sectional side view of a combination of treatment units as
shown
in Figure 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is directed to a treatment unit for treating a fluid in
continuous.
It will be understood that the present invention contemplates employing "a
fluid"
either of organic or inorganic nature.
The treatment unit of the present invention is able to fulfil two roles,
namely the
biotransformation of a substrate and/or the capture of an element, such as a
protein
contained in a fluid. In the present invention, biotransformation means the
transformation of a substrate contained in a fluid into one or several
products with
the aid of reactive materials preferably selected from the group consisting of
an
enzyme such as a carbonic anhydrase or a glucose oxidase, a coenzyme, a
cellular
organelle such as a mitochondrion or a cell-membrane, an animal, plant or
human
cell and a microorganism. Whereas, in the case of the capture of a proteinic
element,
this is achieved with the aid of reactive materials involved in immunological
reactions
or in natural affinity interactions. Such reactive materials are preferably
selected from
the group consisting of an antibody, an antigen, a lectin, an adhesion
molecule and
a biological receptor.
Referring to Figure 1, the treatment unit (10) of the present invention
comprises a
reservoir (12) which includes a fluid inlet (14) for receiving a fluid to be
treated and
a fluid outlet (16) for releasing a treated fluid. Such fluid in the reservoir
is flowing
from the fluid inlet (14) towards the fluid outlet (16). In order to
regularize the fluid
inflow, the treatment unit (10) is linked to a fluid inflow regulator, such as
a pump.
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At least two spaced-apart baffle walls (20) are provided in the reservoir (12)
for
regulating the flow of the fluid therein. The baffle walls (20), which extend
across the
reservoir (12) along all of its width, force a fluid to flow in a tangential
manner during
5 the whole treatment process. The baffle walls (20) also impede the creation
of dead
volume in the reservoir (12).
A reaction chamber (22) is defined between each of the two spaced-apart baffle
walls (20). As can be appreciated, in the preferred embodiment illustrated,
the
treatment unit (10) includes four of these reaction chambers (22).
Nevertheless,
depending on the treatment process, only one reaction chamber (22) may
suffice.
Each of these reaction chambers (22) has an opening (24) for removably
inserting
therein a cassette (18) provided with a reactive material for treating a
fluid.
Advantageously, the cassette (18) also plays a role of "baffle". As a matter
of fact,
the disposition of a cassette (18) in a reaction chamber (22) (such
disposition will be
described herein below) forces a substrate contained in a fluid to encounter
the
reactive material of the cassette (18). In Figure 1, one of these cassettes
(18) is
shown removed from its reaction chamber (22), as the other ones are shown
inserted
in their respective reaction chamber (22). The preferred embodiment shown in
the
figures contemplates employing a plurality of reaction chambers (22) disposed
in
sequence in the reservoir (12) so that a fluid flowing across the reservoir
(12) flows
in a tangential manner through each reaction chamber (22) consecutively.
Furthermore, the number of reaction chambers as well as the dimension of the
treatment unit (10) are a function of the speed of treatment reaction as well
as of the
concentration of substrate in the fluid.
The reservoir (12) finally comprises mounting means for mounting the cassette
(18)
in the reaction chamber (24) in such a way that the cassette (18) is spaced-
apart
from the two baffle walls (20). The mounting means preferably comprises a
support
member (26) disposed between the two baffle walls (20) in order to support a
bottom
edge (28) of the cassette (18). As illustrated in Figure 1, the support member
(26)
may be a shoulder (26) coupled to each of the opposite side walls (62) of the
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reaction chamber (22) when the latter extends transversally in the reservoir
(12). The
support member (26) could also consist of only one shoulder disposed
approximately
in a lower central area of the reaction chamber (22). It will be understood
that
although as a support member a shoulder is preferred, the present invention
contemplates employing other types of support members, such as flanges.
It is also preferable that, once mounted on the support member (26), the top
edge
(30) of the cassette (18) stands higher than the top edge (32) of the baffle
walls (20).
Notwithstanding this particular preference, a treatment unit (10) having the
top edge
(30) of the cassette (18) that stands equal to the top edge (32) of the baffle
walls (20)
could be used even if such treatment unit (10) would not be as efficient.
Consequently and as better seen in Figure 2, the preferable layout of the
structural
elements of the reaction chamber (22) causes the fluid to flow in a zigzag
pattern,
and thus further regulates the flow of the fluid.
Also preferably, the treatment unit (10) comprises a lid (36) for removably
closing an
open top (38) of the reservoir (12). Such lid (36) may be used in order to
avoid any
leakage of the fluid. In other cases, it may be an advantage to use a lid when
the
chosen treatment process involves aseptic conditions. Thus, eventhough the use
of a
lid is a preferable feature, it will be understood that without a lid, a
treatment unit of
the present invention would still keep its treatment capabilities.
Fastening means (60) are provided for securing the lid (36) to the open top
(38) of
the reservoir (12). Despite the fact that the present invention prefers
employing bolts
and nuts as the fastening means (60), it will be understood that any other
fastening
means commonly known will suffice. The number of bolts and nuts as well as
their
dimensions are variable according to the size of the treatment unit used.
In this case, the mounting means preferably further comprises at least one
retainer
(42) in the underface (40) of the lid (36) adapted to hold the top edge (30)
of a
cassette (18). The retainer (42) is located on the underface (40) in such a
manner
that the cassette (18) is set spaced-apart from and substantially in parallel
to the two
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adjacent baffle walls (20). The retainer (42) may be made of semirigid or
spongy
materials, such as a foam-like material. It could be made of a one piece
material, as
in Figure 1 or it could consist of a plurality of stripes of material, each
strip being
capable of retaining a cassette. Other kinds of retainers (42) may be also
considered.
An example of this may be a pair of flanges disposed on the underface (40) of
the
lid (36) so that the top edge (32) of a cassette (18) is trapped between the
flanges.
A pair of flanges could also be used even if, for instance, the flanges were
projecting
sideways from the baffle walls (20) of a reaction chamber (22) instead from
the lid
(36). In this case, the cassette (18) would have to be slipped between the
flanges.
According to a preferred embodiment, baffle walls (20) as described above may
be
replaced by removable baffle walls (70) provided with a reactive material
(Figure 2).
In such a case, the removable baffle wall (70) can take the form of any type
of
cassettes (18) of the present invention. The removable baffle walls (70) will
still force
a fluid to flow in a tangential manner during a treatment process but it will
also play
the role of treating a fluid.
According to another preferred embodiment illustrated in Figure 3, the
mounting
means comprises a biocatalytic bed (44) disposed between the baffle walls (20)
for
supporting the bottom edge (28) of the cassette (18), whereby the fluid is
forced to
pass through the biocatalytic bed (44) in order to be treated. Thus, the
biocatalytic
bed (44) allows the optimisation of biological and/or biochemical reactions by
providing a complementary treatment to the one carried out by a cassette (18).
This
complementary treatment may use the same reactive material or a different one.
The
biocatalytic bed (44) may be made of a granular support such as marbles,
grains,
particle cylinders of different shapes. Preferably, the biocatalytic bed (44)
is made
of a granular support selected from the group consisting of
polymethylmethacrylate,
nylon, polystyrene, polyurethane, silica and alumina. It will be undestood
that any
other granular support capable of immobilizing a reactive material may be
used. The
coupling of the reactive material to the granular support is achieved with any
method
known to one skilled in the art.
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A feature of the present invention is that, depending on the desired treatment
process, the cassette (18) can take different forms in order to be an adequate
support for a reactive material. Therefore, the cassette (18) may be made of a
polymer selected from the group consisting of polymethylmethacrylate, nylon,
polyester and polystyrene. Such polymeric cassette (18) constitutes therefore
a
suitable support for the direct immobilization or coupling of the reactive
material on
one or both faces (34) of the polymeric cassette (18). The coupling of the
reactive
material to the polymeric cassette is achieved with any method known by one
skilled
in the field of the invention.
Alternatively, the cassette (18) may preferably be made of another type of
polymer,
such as plexiglass, or a material such as glass, metal or any other material
suitable
for the characteristics of the type of fluid to be treated. With this type of
cassette (18),
one or both faces (34) of the cassette is covered with a membrane to which is
coupled the reactive material. Such membrane may be made of nitrocellulose,
nylon,
poly(vinylidene)fluoride, chitin, chitosan, agarose, acrylamide, calcium
alginate,
cotton, polyester, rayon or any other membrane that will be apparent to one
skilled
in the field. Therefore, these two types of cassettes (18) which have a
reactive
material either coupled to a polymer or a membrane allow the reactive material
to be
in direct contact with a fluid flowing in the reaction chamber (22).
The cassette (18) may also preferably consist of a dialysis module comprising
a pair
of dialysis membranes and an enclosed space therebetween. Thus, in this case,
the
reactive material is contained in the enclosed space and becomes in contact
with the
fluid when the latter passes through the dialysis membranes.
Referring back to Figure 1, the treatment unit (10) preferably further
comprises
inserting means (46) for inserting a measuring element in the reservoir (12).
Such
measuring element may be a pH electrode or a conductivity probe. The inserting
means (46) may also be used for adding chemical and/or buffer solutions into
the
reservoir (12) for regulating treatment parameters which will be known to one
skilled
in the art. The inserting means (46) preferably comprises an opening (48) in
the lid
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(36) of the reservoir (12) and a plug (50) insertable therein, whereby the
plug (50) is
removed to insert a measuring element or to add a chemical solution. It will
be
understood that depending on the treatment process, more than one opening may
be required. As can be appreciate in Figures 1 and 3, when an opening (48) is
disposed in the vicinity of the fluid outlet (16), it is preferable that the
fluid outlet (16)
be disposed high enough in order to provide accumulation of the fluid. This
will
facilitate the use of a measuring element.
Referring to Figure 4, the present invention is also directed to a combination
of a
treatment unit (10) as defined above with a similar treatment unit (10). The
combination comprises connecting means for connecting the treatment units (10)
together. A tube (52) for hermetically connecting the fluid outlet (16) of one
of the
treatment unit (10) to the fluid inlet (14) of the other treatment unit (10)
is one
example of a connection means that can be used. Advantageously, this
combination
makes it possible to change easily a treatment unit (10) or to modify the
quality of the
fluid to be treated simply by varying the number of treatment units (10). The
size,
shape and dimension of the treatment units (10) and the number of units (10)
disposed in sequence is adaptable according to the needs of a user and to the
type
of application (research or industrial applications).
Advantageously, a treatment unit (10) of the present invention may be linked
to a
decantation unit so as to allow the decantation of one or several reaction
products.
The decantation unit is useful in the extent that one of the reaction products
is
desired in a solid form. The flowing fluid, once treated by the reactive
material, is led
into a precipitation chamber containing a solution capable of reacting with
the
product. A chemical reaction is established which leads to the desired
precipitation.
A discharge means, such as an outlet disposed at the base of the precipitation
chamber of the decantation unit, enables to remove or collect the precipitate
product.
Following the precipitation chamber, a fluid collecting chamber may be
provided in
order to allow the fluid to accumulate itself before being discarded by a
fluid outlet
preferably disposed near the top edge of the decantation unit. The fluid
collecting
chamber may serve also as a second decantation chamber which would allow a
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further precipitation process for products that could have escaped from the
first
decantation chamber.
As mentioned above, the decantation unit can follow one or several treatment
units,
5 but could also be an integral part of a treatment unit of the present
invention. In this
case, a decantation chamber would be in fluid communication with a reaction
chamber (22) in the reservoir (12).
According to another aspect of the present invention, a method for treating a
fluid in
10 continuous is proposed. This method provides great flexibility in choosing
operating
conditions to optimize the treatment process of a fluid. That is, for
instance, the
unique opportunity of removing during the treatment process a cassette (which
includes a reactive material) in order to substitute it for another one with
the same
or a different reactive material. The method according to the present
invention
comprises the steps of:
a) providing a treatment unit (10) as defined above;
b) inserting in the reaction chamber (22) defined between each of the at least
two spaced-apart baffle walls (20) a cassette (18) provided with a reactive
material;
c) mounting said cassette (18) in the reaction chamber (22) spaced-apart from
the baffle walls (20) and thereby defining a zigzag path between the baffle
walls (20)
and the cassette (18) for a flow of fluid flowing across the reservoir (12);
and
d) continuously supplying the reservoir (12) of the treatment unit (10) with a
fluid to be treated and containing a substrate, thereby causing said fluid to
flow
across the reaction chamber (22) following the zigzag path and wherein the
substrate
reacts with the reactive material of the cassette (18), and then towards the
fluid outlet
(16) to release a treated fluid.
Step a) can be modified by further connecting the treatment unit (10) to
another
treatment unit (10). Step a) can be further modified by connecting a
decantation unit
to a treatment unit.
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In a preferred embodiment, step c) is modified by supporting a bottom edge
(28) of
the cassette (18). Step c) may be further modified by retaining a top edge
(30) of the
cassette (18).
The method may further comprise the step of:
e) closing an open top (38) of the reservoir (12) with a removable lid (36).
Preferably, step e) may be modified in order to hermetically fasten the lid
(36) to the
open top (38) of the reservoir (12).
EXAMPLES
Example 1
Type of application
This model allows the use of reactive materials (cofactors and coenzymes)
which are
stuck or bound to a support, such as a cassette (18) according to the present
invention. These reactive materials used can also be integral part of the
material
constituting the support. The fluid to be treated (containing a substrate) is
flowing
along the baffle walls (20) and cassettes (18). When the fluid flows along the
sides
of a cassette (18), the substrate is captured and transformed by the reactive
material
of the cassette (18). The product is then released in the fluid and flows
through the
fluid outlet (16) of the treatment unit (10) of the present invention.
By way of an example, a support or cassette (18) of poly(hydroxyethyl
methacrylate)
containing an enzyme, such as glucose oxidase is prepared according to Schulz
et
al. (1999. Influence of polymerisation parameters and entrapment in
poly(hydroxyethyl methacrylate) on activity and stability of GOD, Joumal of
molecular
catalysisB; Enzymatic. 7: 85-91).
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The preparation of the new support must contain the dimensions of the cassette
(18).
The use of this cassette (18) allows not only the enzymatic transformation of
the
substrate brought on by the fluid but also by the easy replacement of the
spent
cassette (18).
Type of support used
Any support having the following characteristics can serve as a cassette (18)
according to the present invention.
= A rigid structure
= A composition allowing the chemical or physical adhesion of reactive
materials
= A composition compatible with the fluid to be treated
= Preparation of the support that can support the confinement of the reactive
materials (in the case of reactive materials confined in the structure of the
support).
The types of membranes that can be used are:
for support and sequestration: Poly(hydroxyethyl methacrylate, etc.
for support/adhesion or covalent bound: nylon, poly methyl methacrylate,
polystyrene, polystyrene etc.
Example 2
Use of fine membranes resting against the faces of the cassette (18).
Type of application
The side of a membrane that does not contain the reactive material is resting
against
a face (34) of the cassette (18). The cassette (18) can be covered by this
membrane
on each of these two faces (34). The fluid will flow in a transversal fashion
along the
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membrane face covered by the reactive material. Lab experiments show that a
membrane of nitrocellulose can contain between 80 and 100 micrograms of enzyme
by square centimetres of surface. Trials with a cassette (18) having a
nitrocellulose
membrane coated by carbonic anhydrase show that a flow of 240 mI/min is
sufficient
to initiate the treatment. At the end of the treatment, pH readings will allow
the
evaluation of the activity of the enzyme compared to a membrane without any
enzyme. The results show a much more rapid transformation of dissolved CO2 in
water to bicarbonate ions. Since the pH drop is very slow for a membrane
without
enzyme, it is possible to register a decrease from 7.8 to 6.9 in values of pH
in only
15 seconds when the carbonic anhydrase membrane is used.
Type of membrane used
The membranes used must have the following characteristics:
= a thin and malleable membrane,
= a membrane cut to the dimensions of the cassette (18),
= a composition allowing the chemical or physical adhesion of reactive
material,
and
= a composition compatible with the fluid to be treated.
The membranes that can be used are the nitrocellulose, the nylon membranes,
the
PVDF, or any suitable membrane that will be apparent to one skilled in the
art.
Example 3
The use of dialysis cassettes (18) containing free reactive material or
retained in a
hydrogel (agarose, acrylamide, or the like).
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Type of application
Water penetrates the treatment unit (10) at an optimised flow, taking into
account the
type and the speed of the biotransformation and the dialysis of the products.
The
cassette (18) contains the reactive material (such as bacteria, organites or
enzymes)
between two permeable membranes. Water must circulate slowly in such a way
that
promotes diffusion of the substrate across the porous membranes of the
dialysis
cassette (18). The substrate then becomes available for the biotransformation
by the
reactive material. The product of the reaction accumulates between the
interstice of
the two permeable membranes. The difference in concentration between the fluid
that circulates and the one that is present inside the cassette (18) allows
for the
diffusion of the products towards the exterior of the cassette (18). This type
of
application of the system for the treatment of fluids does not require a
chemical or
physical attachment of the reactive material.
Type of membrane used
Any membrane known to a person in the art may be used in this type of
treatment
process. The porosity of the membrane must be superior to the size of the
substrate
to be transformed and of the particles produced following the
biotransformation. The
membrane must be compatible with the fluid to be treated.
Although preferred embodiments of the present invention have been described in
detail herein and illustrated in the accompanying drawings, it is to be
understood that
the invention is not limited to these precise embodiments and that various
changes
and modifications may be effected therein without departing from the scope or
spirit
of the present invention.
