Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
FLUID CONVEYED MATERIAL COLLECTION SYSTEM
BACKGROUND OF THE INVENTION
(0001] The present invention relates generally to the processing of fluid
media by
filtration. In particular, the present invention relates to the processing of
a wide range of fluid
media in order to separate and/or collect substances carried by such media.
[0002] The fluids used in nuclear power plants and at other manufacturing and
processing facilities can be contaminated with substances that should not be
directly released
into the environment, or, on the other hand, may carry valuable or useful
substances such as
metals, ceramics, pharmaceuticals, or biotechnical materials or compounds. In
either case, the
fluid media from such facilities must be processed to remove unwanted or
undesired
constituents of the fluid prior to discharge or reuse, and/or processed to
collect the desired
valuable or useful substances. The fluid media can come from a variety of
sources including,
but not limited to, industrial, pov~er generation utilities and other similar
sources of fluids and
exhaust gases; spent fuel pools; floor drains from nuclear power and
industrial facilitie s. resin
tank drains; evaporator bottoms; and the SOUrC2 Of flLtldS Call C0111e from
other fluid processes
including, but not limited to, those used in metal finishing andlor recovery
operations:
pharmaceutical synthesization or fabrication; ceramic production:
hydrometallurgical and
mining applications; coal cleaning; hydrothermal processinb; mineral
beneficiation: and
bioteehnical material or compound collection. Because of environmental
concerns, ilcreasin~:
disposal costs and other economic considerations, the separation of the.
contaminants and/or
the valuable or useful substances from the l7uids that carry them has become
snore and more
important. The goals of this separation can include: ( 1 ) the removal and
concentration of a
sufficient amount of contamination from the. fluid so that the resulting
effluent can be reused
or released to the enviromnent after further processing. or, in some cases,
directly released or
reused; (2) the removal and concentration of a significant percentage of the
valuable or useful
substances carried by the fluid; (3) the reduction ofthe volume of waste that
must be disposed
of, and/or (4) the availability of a highly concentrated form of valuable
materials suitable for
economical recovery or recycling.
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[0003) A number of techniques are used to attempt to separate substances fiom
fluids, including filtration. ion exchange, evaporation, crystallization and
adsorption.
Generally, filtration is a process in which a separating medium or device
(i.e.; a filter) capable
of removing small particles from a gas or liquid by mechanical (or diffusion
based]
interception is used to separate such small particles (i.e., the "reject"
and/or "concentrate")
from the fluid that passes through the separating medium or device (i.e., the
"filtrate" and/or
"permeate"j. Also, the separation of the substances from the fluid by
filtration is generally
based on the difference between the size of the particles of the substance and
the openings in
the filter medium, but sometimes filtration is also aided by electrostatic
forces,
hydrophobic/hydrophilic interactions and other interfacial phenomena that
enhance or
preclude selective species transport across the membrane, and/or by chemical
reactions.
Moreover, with respect to filtration arid ion exchange, the collected
substances can he
particulate and/or dissolved ions of varying sizes, which commonly requires
these two
techniques to be used in a particular sequence.
(0004) Sometimes more than one type of filter is used. For example. in a
standard
single-pass filtration process, roughing filters an°e first used to
remove larger particles. and
then ever finer, polishing filters (i.e., those filters that are potentiall~~
capable of removing
smaller and smaller sized particulate including. but not limited to, screen
filters. microfilters,
ultra filters. nanofilters, and hyper filters, i.e., reverse osmosis
membranes) are used to
remove smaller particles. By using the various types and sizes of filters in
this manner, this
filtration process may be able to remove a high percentage of the particulate
while attemptin~~
to protect the finer membranes from the damage that could be caused by larger
particles.
Therefore, it is standard practice to rise various sized (and/or types of)
filters in a specific
sequence; with the c-oarser filters (i.e.. filters having larger particle
collection size ratings)
being used first in an attempt to remove the lar~~er particulate, then ever
fin ~r filters in au
attempt to remove the smaller particulate.
[0005] The philosophy of this approach makes good sense for several reasons,
especially when considered from the perspective of having a fluid medium that
is carrying a
moderate level of particulate. In such an environment. if a fine filter is
used first, the amount
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of particulate it would remove would be so great that the filter would quickly
become fouled
with both fme and coarse pat~ticulate, which would cause the flow through the
filter to stop
altogether, and which could occur soon afier being placed in service.
Therefore. by using
filters in sequence. from coarse (roughing] to line (polishing], attempts to
assL~re that the
throughput of each filter is as high as possible. Furthern~ore, because
filters with smaller pore
size are generally more expensive, it makes better economic sense to use the
finer filters for
filtering only the smallest particles and not also for filtering out particles
that could be
removed from the fluid with less expensive filters. Additionally, some fluid
media require
further substance removal after filtration in order to attempt to remove
dissolved substances
from the fluid. This is generally accomplished by sending the filtrate from
the last filter, or
set of filters, to an ion exchanger and/or a reverse osmosis unit, which, in
combination w-ith
the standard filtering method, may result in producin;~ a treated fluid that
can be nearly free of
both particulate and dissolved species.
[0006] The processes just described can work well. and, in general, produce
clean
filtrates an.d/or permeates, potentially remove many of the substances carried
by the fluid, and
may allow for the safe disposal of the unwanted substances. However, they
focus solely cm
obtaining a clean filtrate and not on obtaining an efficient volume of
collected materials,
which would be economically beneficial. if obtained, i.e.. an efficient volume
of collected
materials would essentially consist of only thaw substances intended to be
collected.
[0007] T-~urthermore. because of environmental concerns and the risin~~ costs
associated with the disposal of unwanted substances, e.g., radioactive, toxic,
and/or hazardous
waste, there is a growin~~ need to make a contorted effort to reduce the
volume of the wastes
being disposed of, and, because it is also desirable to recover valuable
and/or useful
substances carried by some fluid media-especially in a highly concentrated
form--there is
also a need for a way to process such fluid wedia so that the valuable and/or
useful substances
can be efficiently and relatively inexpensively collected and%or recovered.
Therefore. based
on the foregoing, a need remains to remove substances from various fluid media
in a way that
results in an efficient collection of such substances, provides for easier
hurdling of the
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substances collected, and does not compromise the quality of the filtrate
and/or permeate
produced.
BRIEF SUMMARY OF THE INVENTION
[000$] According to its major aspects and briefly recited, the present
invention is a
method of filtering and an apparatus or system for processing fluid media in
order to collect
substances carried by such media. The fluid media of interest include, but are
not limited to
waste streams from nuclear power plants, and the fluid media associated with:
metal finishing
and/or recovery operations; pharmaceutical svnthesization or fabrication;
ceramic production;
hydrometallurgical and mining applications: coal cleaning; hydrothermal
processin~~; mineral
beneficiation; and biotechnical material or compound collection. Because the
present system
is able to use multiple passes to highly concentrate the substances of
interest. it can virtually
collect all of the substances of interest to the user in a minimal volume, and
compared to the
prior art processes, the present system also reduces the collection of any
unwanted materials,
yet without affecting the pltrity of the filtrato and/or the permeate. This.
of course. simplifies
the handling of the collected substances. and with resloect to collecting
radioactive
contaminants from a fluid, as an example, but not as a limitation. the present
system is able to
significantly reduce the handling and the. disposal volume of the collected
substances. and.
therefore, is able to reduce the associated disposal costs.
[0009] In order to achieve the collection of virtually all. if not all,
suspended
solids. including, but not limited to, colloids, combined with a reduction in
volume, a portion
of the reject (or concentrate) from an initial step substance collection
device is sequentially or
further processed through an additional processing step having a anal step
substance
collection device, and the ftltrate (or permeate? from this final step
substance collection
device, after such additional processing, is then returned upstream of the
initial step substance
collection device. In other words. the fluid is "recycled'' by being
repeatedly directed back to
the initial step substance collection device and then through the final step
substance collection
device until, through the "recycle to extinetion'~ analogy, vii°tually
all of the substance. of
interest, i.e., the substance intended to be collected, is collected by the
final step substance
collection device (or, in other words, until most. if not all, of the
particulate is collected by the
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final step substance collection device). Then, if required, virtually a11, if
not all, fluids are
removed from the materials collected b~~ the final step substance collection
device through the
use of fluid removal or displacement processes. Afterwards, the collected
substances may be
disposed of if they are unwanted, or recycled and reused if they are valuable
and/or useful.
Notably, in the present system, the initial step substance collection device
has an equal or
higher rejection rate (i.e., it can collect smaller particles or, in other
words, it has a smaller
particle collection size rating) than the Fnal step substance collection
device for the material
to be collected. In other words, the fluid is sequentially processed by first
being directed to a
filter having a smaller collection size rating then the next f Iter in the
filtering sequence.
(0010] More specifically, the additional processing step includes, but is not
limited
to: (1) establishing a high velocity flow across the upstream surface of each
filtering element
contained within the initial step substance collection device so that the
reject or concentrate
(i.e., the substances collected by the iivtial step substance collection
device) can be carried
away from the initial step substance collection device by a reject
recirculation stream carried
within a recycle Loop. This prevents the initial step substance collection
device from
becoming fouled, which would reduce its capacity, and which is troublesome for
some prior
art systems; and (2) diverting a portion of the fluid and reject from the
initial step substance
collection device through the final step substance collection device at a low
flux. The purpose
for maintaining the velocity. the flux. or the- energy input of the fluid
passing tl_~ro,tgh the° f nal
step substance collection device very lov° is to maximize the substance
loading of the final
step substance collection device's flto.rin~e elements, and also to increase
its particle removal
efficiency.
[0011) Since the final step substance collection device will collect
substances
including, but not limited to, those that are valuable. usehil, or desirable,
or. if otherwise used,
to collect substances that are hazardous or toxic. the substances collected by
the final step
substance collection device will normally cause the pressure drop across the
Cnal step
substance collection device to increase, and, when the maximum allowable
differential
pressure drop across the device is reached, or the final step substance
collection device is
filled with substance, and/or other limiting criteria are reached, the final
step substance
CA 02429484 2003-05-23
collection device and/or its filter elements will be replaced with a new or
recycled final step
substance collection device and/or filter elements. Related to this, when
collecting
radioactive contaminants, the final step substance collection device will be
replaced ve~hen the
maximum allowable radiation dose rate, activity level, safe mass levels.
and/or other limiting
criteria are reached.
[0012] The final step substance collection device collects virtually all, if
not. all. of
the particulate, including those particles smaller than its ''particle
collection size rating'"
(which is herein defined as the minimum particle size that can be collected by
the device
including, but not limited to, the sizes normally associated with suspended
particles. dissolved
species and/or macromolecules) because, for all practical purposes, it has a
non-zero particle
collection efficiency over the range of particle sizes carried by the fluid
and, as long as the
particle collection efficiency is greater than zero, the final step substance
collection device
will eventually, after repeated recycling passes, collect virtually all, if
not all, p~uticles
including, but not limited to, suspended solids. dissolved species aald/or
macromolecules.
lvloreover, by recycling the final step substance collection device filtrate
back to the initial
step substance collection device, the concentration of the particles in the
recycle look may
build up to a level where the rate of particle removal in one pass tlwough the
final step
substance collection device may equal the rate of particles beuzg introduced
«kith the fluid
being fed to the initial step substance collection device, thereby
establishing an equilibrimn or
steady-state condition.
[0013] Une conhibuting factor as to why the final step substance collection
device
will collect particles smaller than its particle collection size rating is due
to the process of
particle agglomeration occurring in a cake-like matrix that is primarily
formed by the
substances being collected (but which may also be formed by the introduction
oC "pre-
coating" or "seeding" materials that may be used as a catalyst or stimulus for
filter cake
formation). Agglomeration is a tendency of the particles to form clusters that
interlock. The
interlocking clusters define narrow, twisting passages through a cake-like
matrix that will
allow fluid to flow through the matrix, but, because these passages are
irregular; that is. they
change direction and vary in cross section. this results in a substance
collection action that
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will trap particulate smaller than the particle collection size rating of the
final step substance
collection device. Additionally, particle agglomeration can be enhanced
through the use oh
coagulants, polyelectrolytes, and other similar agents. The use of these
agents is not
preferred, however, and, if used, they must be used carefully since they can
foul the filter
elements of the substance collection devices. If necessary, or desired, the
final step substance
collection device, and/or any of the other substance collection devices, may
be "pre-seeded."'
or "pre-coated" with various materials well known in the field including, but
not limi ed to.
diatomaceous earth, powdered resins, activated carbon, or other granular
materials, to initiate
the collection of the substances including, hut not limited to, colloidal
substances. The use of
this pre-coating can be particularly helpful if the substances contained in
the fluid have a
particle size that is close or smaller than the particle collection size
rating of the substance
collection device. Therefore, agglomeration is just one of the reasons that
smaller, as well as
rated, particles can be collected by the final step substance collection
device. In fact, as long
as any other particle collection mechanism including, but not Limited to,
adsorption, produces
a particle collection efficiency that is greater than zero, agglomeration is
not necessary for the
final step substance collection device to work at all in trapping particles
that are smaller than
the particle collection size rating of the collection device.
[0014) While other forces, suc-O as adsorption, also contribute to the
collection or'
the particles, it is the formation of the cake-like matrix, or cake, of
inarticulate against the
upstream side of the final step substance collection device's filter elements
that provides a
significant and unexpected contribution to the collection of small particles.
The cake in effect
becomes part of the final step substance collection device, and tale formation
effectively
reduces the particle collection size ratins~ and increases the effective
substance collec-tion
depth of the final step substance collection device. which increases the
likelihood that a small
particle that enters the filter will become trapped, adsorbed, or otherwise
collected by the fiiaal
step substance collection device. To help assure cake formation, a to«- flux
(or loin fluid
velocity and/or energy input) is used through the final step substance
collection device to
prevent undue forces from acting on the particulate cake, which could disrupt
the adsorption
forces or break up the particulate cake itself.
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[0015] Additionally, if needed, the system's substance collection e~ciency can
be
improved by a variety of means including, but not limited to: precipitation;
or the previously
mentioned seeding or introduction of other filter pre-coating materials that
can be used to
collect the substances of interest including, but not limited to, the
introduction of materials
that act as a catalyst or stimulus in forming a filter cake or collection
matrix; and/or by adding
substance "eating" bacteria that can transform substances into forms that
allow for subsequent
collection. For example, but not as a limitation, dissolved metal ions, or
other dissolved
species, can be precipitated out of solution for collection by the present
invention system.
This can be accomplished by adding sulfides or other chemicals (e. g., other
precipitating
agents or pH adjusting chemicals) upstream of any of the substance collection
devices
IIlClud117g, but not limited to, the initial step or the final step substance
collection devices.
Preferably, the addition of the agents to the system will take place in a
system feed tank, or a
fluid holding tank, which is located upstream of the initial step substance
collection device.
and which may include temperature adjusting means as well as agitation means
to promote
precipitation. B5~ using precipitation, the dissolved ions can become
suspended in the fluid
and, therefore, be made available for collection instead of having them pass
through the initial
step substance collection device, as part of the initial step substance
collection device's f Itrate
(and/or permeate), which can occur when the particle collection size rating of
the initial stela
substance collection device does not permit for removal of the dissolved
species of interest
tbu t may be precluded by selecting a particle collection size rating flat
mill cause the
dissolved ions to be filtered from the fluid}. In other words. the dissolved
ions can be
precipitated out of the fluid and the suspended solids that result can be
collected from the
fluid (along with or apart from the other particulate) by the final step
substance. collection
device. Moreover, the precipitation of metals, and other dissolved species,
can be so effective
that further treatment downstream of the initial step substance collection
device m.av become
unnecessary, thus saving the costs associated with having to maintain and
operate separate
processing equipment in order to remove dissolved species. In some
applications, however.
this further processing can be effectively and economically provided by
another embodiment
of the present invention system, which will be described below. that is
generally based on
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splitting the fluid processing into a suspended solids removal stage in
combination with a
dissolved ion removal stage.
[0016] The present invention has a number of advantages over other systems. In
particular, it is a filtration system that can collect substances from a fluid
medium while it also
produces a filtrate stream that is sufficiently clean for release or re-use,
and it uses a f nal step
collection device that is easy to handle and. when necessary, suitable for
disposal or recycling,
The present invention system is the first cross-flow filtration system that
allows for the
collection of virtually 100% of all substances of interest contained in a
fluid while also
allowing virtually 100% of the fluid to be removed from the present system for
reuse or
release to the environment. Moreover, other cross-flow systems require that
concentrate
fluids are permanently and/or continuously ''bled-off' from their systems.
This is done to
avoid fouling the membrane scu~faces used in these other systems or to direct
these fluids for
further external treatment. The present invention system, however, eliminates
the need to
remove these concentrate fluids from the present system itself. Furthermore,
these other
systems also require that their collected materials are processed externally.
away fi-om the
collection system, while the design of the present invention system allows for
the in-place
processing of its collected substances.
[0017] Another advantage of the present system is that it avoids the
generation of
an inefficient volume of collected substances by using various volume control
means to limit
the amount of unwanted substances such as excess fluid. Furthermore, the
present system
does this without requiring such additional post-collection processing such as
drying,
solidifying, settling. and possibly centrifuging of the substances collected.
which allows the
present system to avoid the costs associated with these processes. along with
the
corresponding effort. Moreover, the present system eliminates the need for, or
the use of'.
thermal treatment processes to remove fluids from the collected substances,
which can Lie
highly detrimental to the collection of many substances including, but not
limited to. bio-
corripounds. Also, with respect to these additional processes, the present
system avoids or
limits the possible undesirable exposure associated with the collection of
harmful substances.
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[0018] The present invention system may allow for the effective separation of
the
fluid into two primary collection streams, one that primarily contains
suspended solids and the
other that primarily contains dissolved solids. This separation opens the door
for independent
and specific processing of each such collection stream. which can be
accomplished by the
present invention system. The present invention system, however, is very
flexible and,
depending on the application, can be set-up in a variety of configurations
including, but not
limited to: a single-stage two-step embodiment (having a initial step and a
final step substance
collection device); a multi-stage embodiment havilig a single two-step stage
and a single
three-step stage (which has a initial step. an intermediate, and a final step
substance collection
device in the three-step stage); a single-stage three-step embodiment; or any
other
configuration suitable for the application for which it is being used,
including more than two
stages and more than three steps, for example, belt not as a limitation, a
more than three-step
embodiment can have two or more intermediate steps each using the same or a
different
substance collection agent and etch beings used with the same or a separate
final step device in
order to simultaneously collect a variety of substances indivielually.
[0019] A feature of the present invention syqtem, which may rely on either
mechanical or on "solution-diffusion" based devices for the collection of
substances. is that it
successfully removes virtually all, if not all. particulate, notwithstanding
the fact that the final
step substance collection device has a removal efficiency of less than 10U%
per pass. This
success is achieved by repeated recycling of the fluid in combination with the
low 17u~; across
the final step substance collection device. In the present invention, the use
of a low t7u?:
substance collection flow path off o1' the recy:le loop maximizes the system's
per pass
removal efficiency and the loading of solids. i.e.. collected substances. in
the filial step
substance collection device and, consequently. minimizes additional reject (or
concentrate)
treatment. The use of a low flux also extends the life and minimizes the
repl<zcemcnt
frequency of the filter elements used to collect the substances of interest
(or of the substance
collection device itself), and provides numerous other benefits including, but
not limited to:
the elimination of the need to use thermal fluid removal processes, such as
drying; and the
generation of a easier-to-handle superconcentrate (i.e.. the superconcentrate
contains more
solids than liquids malting it easier to use and handle, which, for example,
can cause a
CA 02429484 2003-05-23
reduction in radiation exposure to those personnel involved in. the processing
of radioactive
media, and can lower overall equipment and material costs).
(0020] Another feature of the present invention is that it also takes
advantage of
chemical treatment including, but not limited to p1-1 adjustment, and/or the
addition of
precipitating andior collection agents to the fluid media, preferably,
upstream of the initial
step substance collection device, which alsc»nay include, but is not limited
to, the possible
use of bacteria, and/or the use of sulfides. sulfites or at~y other suitable
chemicals, to facilitate
the collection of dissolved metal ions, andior other dissolved species. This
feature enables the
metal ions, or the other dissolved species. to be removed along with the
suspended substances
originally extant in the fluid medium., which may make it possible to directly
discharge or
reuse the filtrate (or permeate) from the initial step substance collection
device without the
need for further processing steps, such as standard reverse osmosis or ion
exchange.
(0021] Another advantage of the present invention system is that it can be
easily
configured and expanded to meet an individual facility's fluid characteristics
andior
configurations; therefore, it can be readily installed into the i7uid systems
of existing facilities.
oi° it can be operated on a stand-alone basis. Moreover, the present
invention system has a
very small footprint, which, besides adding to a fast set-up time, enables the
system to be both
highly mobile and able to be operated in very small areas. To add to the fast
set-up time and
ease of use, the system can be configured tco include "puicl:-
connect/disconnect"' features. All
of which. besides the system's economy and efficiency. males the system highly
desiravble for
a wide variety of application including. but not limited to. the on-site
processing of fluid
media for remediation purposes or durin~~ the: decommissioning of nuclear
power plants. To
further add to the ease of use, tlne present invention systeun includes a
mufti-purpose container
(andior a modified mufti-purpose container) to house andior process the final
step substance
collection device and/or its collected substances. The mufti-purpose container
(and/or its
modified version) is a combination processing enclosure. transport container,
and disposal
container that allows for the direct processing of the collected substances
(including, but not
limited to, fluid removal andior solidification processes j while the final
step substance
collection device is still attached to the remaining components of the present
invention
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CA 02429484 2003-05-23
system. This is especially convenient and provides for both material and labor
cost savings
by eliminating intermediate handling and processing steps extant in other
prior art systems.
[0022] Besides having reject recirculation streams and/or recycle loops, the
usable
surface area of some of the filter elements is maximized and the chemical
cleaning
requirements of these elements are minimized by the additional feature of
backflushing.
Generally, backflushing is used with the filtering elements of the initial
step and/or
intermediate step substance collection devices to remove materials depositc.~d
on their
upstream surfaces. However, backflushing also may be one of the methods used
to recover
the valuable, desirable, and/or useful materials collected by the final step
substance collection
device(s), and after backflushin'~ the final step substance collection device
may be available
for reuse in the present system. For example. carbon dioxide, other gases,
and/or volatile
fluids can be used to backilush the collected materials from the filter
elements) in order to
recover and/or reuse such substances. Furthermore, the efficiency of
backflushing, as used in
the present system, can be improved by using a pump or by pressurizing the
backflushing
fluid to produce a higlmelocit~~ reverse flow tlwough the filter elements of
the substance
collection device being baclcflushed. Efliciencv also can be improved by iutl-
oducin~~ aiir or
ozone, or any other suitable gas, preferably under pressure. into the backfl
ush fluid and!or
into the reject recirculation stream carried by the rc;cycle loop. and/or by
using all:rasonic
technology to dislodge substances from the filter elements. And. since the
reject recirculation
stream flows across the upstream surfaces) of the initial step substance
collection device at a
high velocity, it would improve bacl:flushing effectiveness by increasing
turbulent flow.
~~hieh would cause. the laminar tlow layer across the surface of the
filtration element's to
decrease allowing more cleaning to occur. which, should increase the usable
lifetime of the
substance collection device being baclvflushed. Additionally, the
effectiveness of
backflushing andior the cleaning oil the initial step and/or intermediate
substance collection
device surfaces may be improved by introducing chemical and/or bacterial
cleaning agents
into the baekflushing fluid, and/or chemical. and/or bacterial, and/or
mechanical cleaning
agents into the reject recirculation stream. This should allow a more
effective cleanin~l of the
particulate from the laminar flow areas of the backflushed collection devices
to occur. In
some applications, instead of directly processing the materials released
daring baclflushing,
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the materials may be collected and stored in a backflush collection tank, and
later released
back into the system for processing or properly disposed of through other
means.
[0023] The present invention is being described with frequent reference to
radioactive contaminants generated at nuclear power plants. I-Iowever, it is
applicable to all
fluid media having suspended particulate. dissolved materials, and/or any
other appropriate
species suitable for collection from such media. For example, bttt not as a
limitation. the
present invention can be used for the rec-overy of valuable and/or useful
substances assc~c-fated
with metal finishing, metal recovery, and/or ceramic production.
[0024] Also included among its many uses, tile present invention system
provides
the advantage of being an alternative to fluid bed processing and its
associated risla, and it
can be used to stabilize, e.g., solidify or vitrify. nuclear reactor and other
hazardous writes
prior to disposal, preferably, as a. part of post-collection processing.
[002] Still another advantage of the present system is that it has ''low-
shocl:'~
characteristics including, but not limited to, the absence of thermal
processing, which
minimizes the introduction of changes to the molecular structure of proteins
and nucleic acids.
so that their original biological propeuies are not degraded. This makes the
present invention
especially useful for the collection and/or concentration of biotechnical
materials or bio-
compounds incIudin<g, but not limited to, pyrogens, proteins, peptide,
eszz~e~zes, ~.%i~-!!ses.
antigens, and/or bacterial cells. The present invention"s characteristics also
make it suitable
for the synthesization or manufacture of phalnnaceutical compounds, and for
many other
suitable uses including, but not limited to. the collection of macromolecules.
[0026] Another important feature of the present invention is the use of
sequential
substance collection devices and flow paths, and the preferable use of a final
step st2bs2ance
collection device having a particle collection size rating that is equal to or
laa-ger than the
particle collection size rating of the initial step substance collection
device. This feature is
counter-intuitive because, in the prior art, fluid media are typically passed
through a series of
filters. for example, beginning with coarser filters having a large particle
collection size ratiny~
and proceeding through finer filters having smaller and smaller particle
collection size ratings.
13
CA 02429484 2003-05-23
However, it should be noted that while this is the preferred particle
collection size
configuration, there may be uses of the present system in which it would be
desirable to have
a final step and/or an intermediate step substance collection device with a
particle collection
size rating that is smaller than the collection size rating of any of the
preceding substance
collection device in the sequence of collection devices.
(0027] Still another feature of the present invention is the use of a low flux
through the final step substance collection device to trap particles,
including those smaller in
size than the particle collection size rating of the final step substance
collection device. Since
this combination eliminates the need fbr, or the use of. more. expensive
particle collection
devices including those that have to be hi~~hly efficient at typical single-
pass processin~~, the
present invention system provides greater levels of substance collection at
lower costs than
would otherwise be achievable.
(0028] Other features and their advantages will be apparent to those skilled
in the
art of collecting substances from a fluid medium fiom a careful reading of the
L>etailed
Description of the Invention accompanied by the followings Drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRA'~VINGS
(0029] Fig. 1 is a schematic drawing of a single-stage two-step system for
collecting substances from a fluid, m~co_rdinp tn a prei_'Pr-f-Pd
er_n_hCrlil??ent Of t14 h~-~s~;~t
invention.
(0030] Fig. 2 is a schematic drawing of two-stage s~~stem far collecting
substances
from a fluid, according to another preferred embodiment of the present
invention.
[0031] Fig. 3 is a schematic drawing of single-stage three-step system for
collecting substances from a fluid, according to another preferred embodiment
of the present
invention.
[0032] Fig. 4 is a schematic drawing of a final step substance collection
device.
according to a preferred embodiment of the present invention.
14
CA 02429484 2003-05-23
[0033] Fig. 5 is a schematic drawing of a modified mufti-purpose container
used
for post-collection processing, and a standard mufti-purpose container, which
can be used to
carry and store a final step substance collection device after post-collection
processing.
according to another preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE IN~~ENTION
[0034] The present invention is a method, apparatus and system for processing
fluid media in order to collect substances carried by such media. The fluid
media of interest
include, but is not limited to, waste streams from nuclear power plants,
exliaust or other uses
from power plants or other industrial, commercial, or municipal facilities,
and fluid media
associated with industrial, commercial, or municipal operations including. but
not limited to:
metal finishing and/or recovery operations; pharmaceutical comhoimd
synthesization or
manufacture; ceramic production; hydrometallurgical and miming applications;
coal cleaning:
hydrothermal processing; mineral beneficiation; and biotechnical material or
compound
manufacture and/or collection. The present system, compared to the prior art
processes.
reduces the volume of uwvanted materials collected without affectin~,~ the
purity of the filtrate
and/or the permeate, and it also simplifies the handling of the collected
substances due to,
among other items, the generation of a superconcentrate of such substances. 1n
particular. the
present invention is an improvement over the prior art processes because it
introduces a
method of using substance collection devices that produces a lower volume of
waste. i.e..
unwanted substances, from being collected while maximizing the collection of
the substances
of interest. Moreover, the substances of interest are collected in a highly
concentrated form so
that the collection volume of these substances is minimized as well. This, oh
course,
simplifies the handling and reduces the costs associated with the disposal or
recoverv° of the
collected substances. For example, with respect to collecting radioactive
contaminants from a
fluid, the present system is able to significantly reduce the volume of the
substances to be
disposed of and. therefore, the associated disposal costs. Moreover. the
present system may
preclude the necessity of having to perform additional costly processing steps
prior to the
disposal or reuse of the collected substances and/or the release or reuse of
the filtrate.
Generally, the collection devices of the present invention are comprised of
number of
filtration media including, but not limited to screen filters. microfilters,
ultra filters.
I
CA 02429484 2003-05-23
nanofilters, and hyper filters (i.e., reverse osmosis membranes) that may be
of the cross-flow
or of the regularly backflushed dead-end type. Generally, when used herein,
"reverse
osmosis" or a "reverse osmosis membrane" is capable of retaining particles
(and/or
substances) having a size of about 0.0001 microns or larger including, but not
limited to, ions,
sugars, synthetic dyes, proteins, emulsions, viruses, carbon black, paint
pigments, indigo dye.
and/or bacteria. Generally, when used herein, a "nanofiltration membrane'' is
capable of
retaining particles (and/or substances) having a size of about 0.0005 microns
or larger
including, but not limited to, ions. sugars, synthetic dyes, proteins,
emulsions, viruses. carbon
black, paint pigments, indigo dye, and/or bacteria. Generally, when used
herein. an
"ultrafiltration membrane" is capable of retaining particles (and/or
substances] having a size
of about 0.005 microns or larger including, but not limited to, proteins,
emulsions, viruses.
carbon blaclc, paint pigments, indigo dye, and/or bacteria. Generally, when
used herein. a
"microfilter'' is capable of retaining particles (and/or substances) having a
size of about 0.0~
microns or larger including, but not limited to, proteins, emulsions, viruses,
carbon black.
paint pigments, indigo dye, and/or bacteria. Furthermore, these devices
generally have
different operating pressure ranges. for example. the operating pressures
range from about
10-40 psig for microfilters and ultrafilters to about 1000 prig for reverse
osmosis membranes.
~UU35] A preferred embodiment of the present invention is illustrated in FIG.
1.
As shown in FIG. 1, a source of fluid media carrying suspended and/or
dissolved materials for
processing by the present invention substance collection system 1U is shown as
a fluid l7oldin'~
tank 11U. The use of a fluid holding tac~l: 11U is the preferred method of
providing the source
of fluid for the substance collection system 1U when used in a stand-alone
conf guration. and
in some facility based applications. This, however. is not the only
configuration that can be
used for the present invention system 1U (oi° ~ or 15 as shogun in
PICis. 2 and 3 respectively)
and. since the substance collection system 1U has a relatively small footprint
and can be easily
configured and expanded to meet an individual facility's fluid characteristics
or system
configuration needs, the present invention system is capable of being set-up
and operated in a
very small open area at a variety of facilities. In other words, while two of
the preferred
embodiments are shown to be attached to a fluid holding tank 11 U, the fluid
holding tank 11 (1
is not always used and may be considered to be an optional component of the
present system
16
CA 02429484 2003-05-23
(or 5), and the present system 10 (or 5 andfor 15 as shown in PIGS 2 and 3.
respectively)
should be considered as being attachable to any appropriate source of a fluid
medium
including, but not limited to. being directly connected to a facility's fluid
system. The fluid
medium, which can include suspended particulate and/or dissolved materials
including, but
not limited to, metal ions, salts, bio-compounds, or other dissolved species,
is preferably
drawn from the fluid holding tank 110 (or source of the fluid medium) by a
pump 120 if the
feed pressure is insufficient, or taken directly from the tank 11U or other
fluid source if the
feed pressure is sufficient, and is then directed via a conduit 122 to a
reject recirculation and
recycle Loop pump 130 which is in fluid connection with an initial step
substance collection
device 150. While the use of a pump is the preferred method of providing a
driving force for
the fluid throughout the present invention. other flow creating methods can be
used including,
but not limited to. those that use gravity, pressure and!or thermal
differences, or those which
involve rotating or spim~ing the filter elements. Preferably, the initial step
substance
collection device 150 (or 250 of a three-step system described in another
preferred
embodiment of the present invention, which is down in FLGS. 2 and 3) is an
ultrafiltration or
a reverse osmosis membrane type filter; however, any other suitable mechanical
or diffi~sian
based substance collection device, i.e" filter element, can be used including,
but not limited
to, a nanofilter, a sintered metal filter, a microfilter, or any other
substance collection device
that can collect particles larger than about O.OU01 micrometer in size. The
initial step
substance collection device's suitability is i~ased on, among oti~er items,
the characteristics of
the fluid medium and of the substances to be collected along with a
requirement that the
particle collection size ratily for the initial stelo substance; collection
device 150 (or 250) is
preferably equal to or smaller than the particle collection size rating for
the final step
substance collection device 200 (or 27U, and the intermediate step collection
device 2G(i in the
three-step system embodiment). When the term ''particle' is used herein. it
refers to both
suspended solids as well as to dissolved ions or othc;r dissolved species that
are carried by the
fluid, and can be precipitated out of the fluid or can be collected by
appropriately sized
filtration media, i.e., filter elements. \~~hen the term ''Substance'' is used
herein, it refers to a
particular kind of matter or material to be collected that is generally
composed of such
particles. Moreover, when the term "substance" is used in either its singular
or plural forms
17
herein it can be construed as being either singular and/or plural depending on
the context of
usage and/or depending upon the application in which the present invention
system is being
used. Furthermore, the terms "permeate" and "filtrate," as used herein, should
be construed as
being interchangeable. Additionally, when used herein, the word "conduit"
means a pipe or hose
together with fittings, valves, flanges, and other associated piping and/or
flow controlling
components adapted for conveying the fluid that flows through it. Since the
purposes for and the
use of piping and flow controlling components are well known, with the
exception of the piping,
these other associated piping and/or flow control components are not generally
shown in the
figures. Some examples of valves that are not shown are isolation valves,
which can be of a gate,
ball, or any other design; check valves, which can be of a single-gate, double-
gate or any other
design, and valves used for throttling flow, which can include, but are not
limited to needle
valves. The flow controlling components can be of the type that are operated
manually, and/or by
controllers, which can include, but are not limited to, electromechanical,
pneumatic, and/or
hydraulic operators.
[0036] Prior to the fluid medium reaching the initial step substance
collection device 150,
a precipitating agent such as those that include a sulfur based molecule,
e.g., a sulfide or sulfite,
can be introduced into the fluid medium; however, any other agent that would
be suitable for use
with the fluid medium and/or the dissolved substances to be collected may also
be used as well,
including, but not limited to, pharmaceutical fabrication or synthesization
agents, ceramic or
metal recovery agents, other chemical agents, bacterial agents, biotechnical
material or bio-
compound agents, and/or any other agent that would be suitable for the
recovery of valuable
and/or useful substances. Therefore, any form of the terms "precipitating
agent," "agent" or
"reagent," or "chemical" can be considered to be interchangeable when any of
these terms are
used in the context of collecting the substances from the fluid media
including, but not limited to,
those substances such as contaminants, metals, dissolved species, substances
associated with
pharmaceutical fabrication or synthesization, biotechnical materials or bio-
compounds, and/or
any other valuable and/or useful substances that can be collected with the
present invention
system described herein. Preferably, a precipitating agents) holding tank 100
is attached via a
feed tube 102 to the fluid holding tank I 10 in order to introduce the
precipitating agents) into
the fluid medium. The primary purpose of
18
CA 02429484 2006-05-04
CA 02429484 2003-05-23
introducing the precipitating agents) is to cause the dissolved radioactive
metal ions, non-
radioactive metal ions, and/or any other dissolved species of interest in the
fluid medium to be
precipitated out of solution. For example. but not as a limitation. the metal
ions can include
cobalt, manganese, and iron, which will form metal sulfides ~~hen exposed to a
sulfide-based
precipitating agent that is introduced into the fluid. Other metals of
interest rnay include: but
are not limited to, gold. copper, uranium. and silver. w~hic.h may be
available for recovery
from a variety of comrnerciai applications including. but not limited to,
leaching operations.
Preferably, the precipitating agents) used will be comprised of biologically
benign anions and
cations, and the concentration of the precipitating a~~ent(s) used will be
selected to match the
dissolved species concentration on a mole eduivalent basis-with some excess in
tile feed to
account for metal ion, and/or other dissolved species, level changes.
Regarding the
introduction and use of the precipitating agent(s), it is important and
preferable to introduce
the precipitating agents) sufficiently in advance of the initial step
substance collection device
150 (which includes the possibility of introducing the precipitating agents)
upstream of, or
prior to, the fluid holding tank 110) so that tl~e precipitating agents) has a
chance to react
with the dissolved species in the fluid medium prior to reaching the initial
step substance
collection device 150. Furthermore, the precipitation reaction may be improved
through the
use of agitation and/or stirring means. temperature control means, and/or
pressure control
means, which may be incorporated into the fluid holelin~~ tank 110 and/or the
piping system
leading to the initial step substance collection device 150.
(0037] The initial step substance collection device 150 is used to reject
particles of
about the same size and larger than its particle collection size rating. and,
if the loarticle
collection size rating is large enough, it will allow appropriately sized
dissolved species to
pass through it along with a portion of the fluid medium. Preferably, the f
prate (,or permeate l
from the initial step substance collection device t50 is forwarded via another
conduit 1?5
back to the facility's fluid system, or to a filtrate/permeate holding tank
630 for samplings
and/or storage prior to release to the environment or reuse. Optionally. an
ion exchange
polisher and/or a reverse osmosis unit 140 may be attached between the initial
step substance
collection device 150 and the filtrate/permeate holding tank 630 (or the
facility's fluid
system). Generally, the ion exchange polisher and/or a reverse osmosis unit
140 will allow
19
CA 02429484 2003-05-23
purified fluid to pass through to the ftltrateipermeate holding tanlc 630 (or
baelc to the
facility's fluid system) and will remove dissolved species not previously
removed. More
specifically, the filtrate and/or permeate from the ion exchange polisher
and/or reverse
osmosis unit 140 is forwarded via conduit 125 to the filtrate/permeate holding
tank 63(1 where
it can be sampled for purity and then reused or released to the environment if
it meets release
criteria (or the f Itrate and/or permeate can be directly forwarded to the
facility"s fluid
system). However, depending on the fluid medium and the substances of
interest. tile ion
exchange polisher and/or reverse osmosis unit 140 may not be needed if. for a
particular
application, the present invention system, through its filter media selection,
confi~~uration
and/or precipitation process used. is effective in removing a sufficient
percentage of the
dissolved species prior to the fluid passing through the initial step
substance collection device
150 and entering conduit I25. The concentrates from ion exchange polisher
and/or reverse
osmosis unit 140 may then be forwarded for farther processing 142 in
accordance with the
prior art method, or, preferably, they can be directed tlwou~lh conduit 400 to
the recycle loop
164 where the concentrates of the ion exchan~~e polisher and!or reverse
osmosis unit 14(1 can
be processed, and its constituent substances collected, by using the
components of the present
system as shown in FIG. 1.
[0038) While the present invention system can provide a filta~ate (or
permeate)
fluid that would be releasable to the environment and/or reusable without the
need for the ion
exchange polisher and/or reverse osmosis unit 140, in some applications.
however, the
precipitation means and/or the filtration media are not efficient or are
unable to collect at
sufficient amount of the substance sough' to be collected. therefore. the use
of an ion
exchange polisher and/or reverse osmosis unit 140, or the use of any of the
other preferred
embodiment to be described below, will be necessary 20 obtain the substance
collec-Lion
results sought to be achieved. When necessar~-~ to use an ion exchange
polisher and/or reverse
osmosis unit 140, or any of the other preferred embodiments to be described,
the present
invention system can be viewed as preferably having two separate processing
portions or
stages. Preferably, these stages will be a suspended substance collection
stage and a dissolved
substance collection stage, and while these stages are shown in FIGS. 1 and 2
as beings
physically combined in one apparatus it should be noted that the different
substance collection
CA 02429484 2003-05-23
stages can be operated as stand-alone systems, i.e., the stages can be
operated in combination,
in stand-alone configurations, or in some combination of both. While it is
preferable that the
stages are a suspended substance collection stage followed by a dissolved
substance collection
stage, any other suitable configuration of stages can be used as well.
[0039] Referring to FIG. 1, the following is a more specific description of
the
initial step substance collection device 150 and the two-step collection
system and method.
Through the use of pumps and/or piping and other associated components
including, but not
limited to, various types of valves, the .fluid containing the substance, or
substances, of
interest is first directed as a feed stream 160 from the fluid holding tank
110 (or the fluid
source) to the upstream side of the initial step substance collection device
150; where a
portion of the fluid passes through the initial step substance collection
device 150 as a filtrate
and/or permeate stream 162 or 262, and a portion of the fluid along with a
portion oi' the
particles that are rejected or prevented From passing through the initial step
substance
collection device 150, i.e., reject (and/or concentrate). is directed to the
final step substance
collection device 200 for at least one additional processing step. Preferably,
the additional
processing step includes, but is not limited to: (1 j using a recycle loop
1.64 to establish a high
velocity flow across the upstream side surfaces) of the filtration elements of
the initial step
substance collection device I50 (preferably, the initial step substance
collection device I50
has at least one ultrai:iltration membrane) so that the reject (and!or
concentrate) and the fluid
form a reject recireulation stream carried by the recycle loop 1.(j4: and (?)
diverting a portion
of the reject recireulation stream carried by the recycle loop 1G4 into a
substance collection
flow path 172, which directs this fluid stream to and through the final. step
substance
collection device 200 at a low flux. :~llou~~ with the use of valves and/or
other flow control
devices, the velocity of the fluid in the recycle loop 164 is maintained
through the use of a
reject recirculation and recycle loop pump 130, and tile flu,: through the
final step substance
collection device 200 is maintained by a pump 180 and a controller 182, which
also causes the
filtrate from the final step substance collection device 200 to lee
transported back to the
recycle loop 164 through conduit 165 so that it is returned for another pass
through the initial
step substance collection device 150. The velocity, or flux of the fluid
passing through the
final step substance collection device 200 is maintained very low to minimize
the introduction
21
CA 02429484 2003-05-23
of energy and to maximize the solids, i.e., substance, loading and the per
pass efficiency of
the final step substance collection device 200. Preferably, the flux, through
the use of the
pump 180, the controller 182, and possibly through the proper setting of
valves and/or other
flow control devices including, but not limited to, throttle valves, is set so
that the flux is at
the low end of the flux that would be required to maintain flow through the
final step
substance collection device 200. This will assure that the particles carried
by the fluid in the
substance collection flow path 172 can interact with each other and the filter
elements in order
to form a "cake" of particles on the upstream side of the final step substance
collection device
200. Tlus self generated cake permits the fluid to flow through passages
defined vs~ithin it.
These passages are highly irregular in cross-section and direction so that the
flow of fluid
through the cake matrix makes frequent changes in direction and speed, and,
because of these
varying flow characteristics, the matrix will tend to trap the small particles
flowing with the
fluid. and as the matrix grows larger it will become even more effective. In
other words. the
final step substance collection device 200, in combination with the low flux.
collects,
concentrates, and removes the fluid from the substances carried by the fluid.
[0040] At steady state conditions, FCC = RC~iE, where F is the fluid feed rate
to
the initial step substance collection device 15(); R is the fluid feed rate to
the final step
substance collection device 200: CF is the total suspended solids
concentration in the fluid
feed to initial step substance collection device 150: Cu is the total
suspended solids
c.oneentration in the fluid feed to the final step substance collection device
200; and h, is the
per pass removal efficiency of the final step substance collection device
2()0. Under the
assumption that removal efficiency remain the sane for a driven particle size
as the laarticle
concentration changes after each pass, in equilibrium. the final step
substance collection
device 200 is close to 100% efFective in trappin g all particles in the fluid;
however. on anv
pass, its removal efficiency can be lower than 100°io, even much lower,
Por example. if the
removal efficiency is 50% and the fluid contains 100 parts per million ("ppm"j
of solids, the
first pass through the final step substance collection device 2U0 removes '~0
ppm. The second
pass through the final step substance collection device 200 removes an
additional ? ~ ppm.
The third pass removes another 12.~ ppm, and in ten passes 99.9% of the
particulate is
removed.
CA 02429484 2003-05-23
[004/] The final step substance collection device 200 of the present system
has a
particle collection size rating larger than or equal to that of the initial
step substance collection
device 150. Preferably, the initial step substance collection device 150 uses
an ultrafiltration
membrane type filter: however, any other suitable filtering element can be
used in this
substance collection device including, but not limited to, filters and/or
membranes having a
wide range of particle collection size ratings, a nanofilter, a reverse
osmosis membrane, a
sand or other fine particle filter, a sintered metal filter. and/or any other
suitable filter and/or
membrane device that may be of the cross-flow or of the regularly backllushed
dead-end type.
Generally, the suitability of the filter and/or the membrane used is
determined by the
properties of the fluid medium and the substances to be collected (e.g.,
substance size and/or
chemical properties) and the requirement that it is preferable that the
particle collection size
rating of the initial step substance collection device 150 is equal to or
smaller than the particle
collection size rating of the final step substance collection device 200, and
floe further
requirement that a filter cake can be formed on the final step substance
collection device 200.
In some applications, however, it may be preferable that the particle
collection size rating of~
the final step collection device 200 is smaller that the panicle collection
size rating of the
intial step substance collection device 150. FLU~thermore, the initial step
substance collection
device 150 can use more than one filter andior ~riembrane element in either a
sequential ancl/or
a parallel flow confi~~uration for either or both the fluid feed flow 1G0 and
recycle loop .1G4
rio~v paths.
(0042] Preferably, the final step substance coll~etio~.~ device 200 is a n
~icrofilter
type filter; however, any other suitable filtering element can be used in this
substance
collection device including, but not limited to. filters and/or membranes
having a «aide r~u~ge
of particle collection size ratio<~s, an ultrafiltration membrane. a
nanofilter, a reverse osmosis
membrane, a sand or other fine particle filter. a sintered metal filter,
and/or any other suitable.
filter and/or membrane device. Generally, the suitability of the filter and/or
membrane used
for the final step substance collection device 200 is determined by the
properties of the fluid
medium and the substances to be collected, e.g., substance size and/or
chemical properties,
and the requirement that it is preferable that the particle collection size
rating of the final step
substance collection device 200 is equal to or larger than the particle
collection size rating of
CA 02429484 2003-05-23
the initial step substance collection device 150, and the further requirement
that a filter cake
can be formed on the final step substance collection device 200. In some
applicaltions,
however, it may be preferable that the particle collection size rating of the
final step substance
collection device 200 is smaller than the particle collection size rating of
the initial step
substance collection device 150 (or the intermediate step substance collection
device 260 to
be described later). Also, in some applications, the final step substance
collection device
and/or filter elements) of the final step substance collection device 200 (or
27U in a three step
embodiment) may need to be "pre-coated" andior "seeded" (i.e., a material that
acts as a
seminal layer of; and/or as a catalyst or stimulus for, the formation of the
filter cake, and/or
for carrying a precipitating agent to provide another means to start or
further enhance
dissolved ion collection is introduced to the upstream side surfaces) of the
filter elements of
the substance collection device 200 (or 270 in a three step embodiment)). In
other words, in
some applications it may be necessary, or desirable, to pre-seed or pre-coat
the final step
st2bstance collection device 200 (or 270 in a three step embodiment) with one
or more
materials well known in the field including, but not limited to, diatomaceous
earth, powdered
resins, activated carbon, or other tranular materials; however, any other
similar material that
would be suitable for starting filter cake formation and/or dissolved species
collection can be
used to initiate the collection of the small substances including. but not
limited to, colloidal
substances. The use of this pre-coating, can be particularly helpful if the
substances contained
in the fluid leave a particle size that is close to or is smaller than the
particle collection size
rating of the substance colle;etion device (for example. but not as a
limitation. the particle
collection size rating may be large and/or other factors may require that a
material be loaded
onto the upstream side surface of the tiller elements to act as a catalyst or
stimulus for filter
calve formation). Furthermore, the final step substalxce collection device 200
can also use
more than one. filter aaxdior membrane element in eitlxer a sequential and/or
a parallel l7ow
configuration for the substance collection flow path 172 flow. Moreover. tlxe
final step
substance collection device 200 can use a small cartridge type slip filter, or
anv other similar
suitable filter that can be disposed of at a disposal site an dior be reused
by backflushing.
[0043] Besides having a reject recirculation stream and a recycle loop 104.
the
usable surface area of the initial step substance collection device 150 (and
the surface area of
24
CA 02429484 2003-05-23
some of the other filtering elements to be discussed below] is maximized and
the chemical
cleaning requirements are minimized by backflushing. Generally, backflushing
would be
used to clean the filter elements of the initial step substance collection
device 150 by
removing materials deposited on their surfaces. However. backflushing also may
be one of
the methods used to recover the valuable, desirable. and%or useful materials
collected by the
final step substance collection device, and after bac.kflushing, the final
step substance
collection device may be available for reuse in the present system. As an
example, but not as
a limitation, carbon dioxide, other gases, and/or volatile fluids can be used
to baclflush the
collected materials fr0112 the filter element in order t0 reCOVer aIldIOr
rettSe SlICh SLlbStallCeS.
Furthermore, the efficiency of backflushin~a can be improved by using a pump
or by
pressurizing the backflushing fluid to produce a high velocity reverse flow
through the
substance collection device 150 during baclcflushing, and/or by using the
reject reeirculation
stream"s high velocity flow across the upstream surfaces) of the filter
elements of the initial
step substance collection device 150. Anv or all of these technidues should
cause an increase
in turbulent flow, which would cause the laminar flow layer across the
surfaces of the filter
elements to decrease, which may cause a more effective cleaning to occur, amd
which,
relatedly, should increase the usable lifetime of the substance collection
device being
backflushed. Additionally, the effectiveness of bacl<fltzslun~~ and!or the
cleaning of the filter
elements of any of the substance collection devices may be improved by
introducing chemical
and%or bacterial cleaning agents into the bacl~flushing fluid. and/or
chemical, and/or bacterial,
and/or mechanical cleaning agents into the reject recirculation stream, so
that a more effective;
cleaning of the pat~ticulate from the la~xtinar f low areas of the
backflushe,d collection devices
may occur. Moreover, efficiency tray be improved by introducing air, ozone. or
anv other
suitable gas, preferably under pressure, into the baclcflush l7uid and/or into
the reject
recirculation stream carried by the recycle loop 1G4, and!or by using
ultrasonic technoloy>v to
dislodge substances from the filter elements. After performing backflushinya.
instead of
directly processing the materials released from the filtering surfaces as a
result of
backflushing, in some applications, the materials may be collected and stored
in a baclcf7ush
collection tank, and later released back into the system for processing or
disposed of
externally through other means. Importantly, the method and manner in which
substances are
'? 5
CA 02429484 2003-05-23
collected in the present invention provides for the recovery of substances
that previously
could not be efficiently andlor economicall~° recovered by other
systems, especially those
using drying processes; thereby. enabling tile recovery of these substances
for the first time.
For example, but not as a limitation. bia-compounds that cannot be thermally
treated, e.'~., by
freeze-drying or evaporation, may be recoverable with the present invention
system.
[0044] Referring to FIG. 2, another preferred embodiment of the present
invention
system is shown. This embodiment is a two-stage substance collection system 5
that uses the
two-step collection system previously described. as a primary collection
stake, as well as a
three-step collection system as a secondary stage. As previously mentioned,
this method is
preferably used for substance recoveries where the substance sought is both
dissolved and
suspended, and precipitation and/or filter media selection is not efficient or
sufficiently
capable of reducing the amount of the dissolved substance to desired levels.
Preferably. the
two-stage collection system can be used to separate the collection of
suspended and dissolved
substance into two independent process sta~.:es. These stages can be operated
in combination
or as separate stand alone systems with or without tine other stage, and,
while the collection
mechanism for tile first substance collection stage. is preferably different
than the one used
with the second stage, both use sequential substance collection devices and
sequential
filtering flow(sj. This allows for the addition or introduction of specific
treatment steps,
which can be common to both stages, but, depending on the substances sou~~ht
to be collected
and/or the fluid meditum, these treatment steps are not limited to this
commonality-. 'fhe
second stage will now be described accordin~~ to a preferred three-step
embodiment; how ever.
the second stage is n.ot limited to this number of filter steps and any other
numbet° of steps or
munber of collection devices suitable for the substances sought to be
ec>llected and%or the
fluid medium of interest can be used as well. Moreover. another embodinvent of
the present
invention uses multiple intermediate step suhstance collection devices 260,
each with it o~im
separate means for introducing precipitatin~~ agents. which allows for the
possible
introduction of different agents, and each having its reject collected by a
separate final step
substance collection device 270. This provides for the possible simultaneous
collection
and/or recovery of multiple substances from floe fluid. Therefore, while these
components
260 and 270 (and the conduit 412 for introducing the precipitating agents
and%or optionally
2G
CA 02429484 2003-05-23
conduit 410 for introducing the evaporator bottoms or concentrate of an
evaporator 6~()
and/or the reject from a centrifuge 655) are shown as single components, it
should be kept in
mind that these components could be viewed as possibly mirrored multiples of
themselves.
Therefore, when using multiple filter steps, or multiple filter devices in a
step, it also should
be kept in mind that the user is provided with the flexibility of~ using
different treatment
processes with any or all of the different filters andior filter steps being
used. The fle~cibilitv
of the present system is further illustrated by another preferred embodiment.
which is shown
in FIG. 3.
[0045] FIG. 3 shows that the three-step system may be used as a single-stage
collection system as well. and, since the three-step system provides the basis
for the
embodiments shown in both FIGS. 2 and 3, the following description applies to
the three-step
system shown in both figures.
[0046) The three-step system uses an initial step substance collection device
250,
an intermediate step substance collection device 260. and a final step
substance collection
device 270. The intermediate step substance collection device 260 has a
particle collection
size rating that is preferably equal to car larger than tlae particle
collection size rating of the
initial step substance collection device 250 and is preferably equal to or
smaller than the
particle collection size rating,? of the final step substance collection
device 270. Preferably, the
tluee-step system ~~~ill be comprised of: an initial step substance collection
device 250 that is
comprised of a reverse osmosis membrane type Clter and/or filtr°ation
unit; an intermediate
step substance collection device 26U that is comprised of an ultrafiltration
membrane type
filter; and a final step suhstance collection device 270 that is comprised of
a microiilter.
However. any other suitable filtering elements can be used in these substance
collection
devices including. but not limited to. nanofilters. reverse osmosis membranes.
sand c>r other
fine particle filters, sintered metal filters, and/or anv other suitable
filters andior membrane
devices that may be of the cross-f3ow or of the re~,mlarly bacl:llushed dead-
end type.
Additionally, as previously described. the use of "pre-coating" andior
"seeding" may be
required or desired. Generally, the suitability of the filters and/or
membranes used is
determined by the properties of the fluid medium and the substances to be
collected. e.g..
?7
CA 02429484 2003-05-23
substance size and/or chemical properties. and the requirement that the
particle collection size
rating of the initial step substance collection device 250 is preferably equal
to or smaller than
the particle collection size rating of the intern Mediate step substance
collection device 260 and
the particle collection size rating of the intermediate step substance
collection device 260 is
preferably equal to or smaller than the particle collection size rating of the
final step substance
collection device 270, and the further requirement that a filter cake can be
formed on the
filtering elements used in the final step substance collection device 270. In
some applications,
however, it may be preferable that the particle collection size rating of the
final step substance
collection device 270 is smaller than the particle collection size rating of
the intermediate step
substance collection device 260 and/or the initial step substance collection
device 250, and/or
the particle collection size rating of the intermediate step substance
collection device 260 is
smaller than the particle collection size rating of the initial step substance
collection device
250. Furthermore, each of these substance collection devices 250, 260. and 270
can use more
than one filter and/or membrane element in either a sequential and/or a
parallel flow
configuration for either or both fluid feed flow and recycle loop flow.
[0047] In operation. instead of having one reject recirculation stream and
recycle
loop 164 as previously described for the two-step system, there are two stl-
eams and two
recycle loops 264 and 268, which are formed through the use o:f~ pumps andior
piping and
other associated components includin~~. but not limited to. various types of
valves and flow
control components. Preferably, as shown in F1G. 2, the source of the Iluid
medium
containing the substances of interest is the filtrate (and/or permeate) of a
primary collection
Stag e, which is preferably the filtrate (and/or permeate) of the previously
described initial step
substance collection device 150; however, any other source of fluid media
could be used
lllClLld111g, but not limited to, other filtration systems. (e.g.. other uvo-
step and/or three-step
systems), fluid holding tanks, or direct connections to a facilitws fluid
system (as shown in
FIGS. 2 and/or 3). The fluid medium is first directed as a feed stream 262
from the fluid
source to the upstream side of the three-step system's initial step substance
collection device
250; where a portion of the fluid passes through that initial step substance
collection device
250 as a filtrate and/or permeate stream 263 that is directed via conduit 625
to the
flltrate/permeate holding tank 630 (where it can be sampled for purity and
then reused or
CA 02429484 2003-05-23
released to the environment if it meets release criteria), or the
filtrate/penneate can be directly
forwarded to the facility's fluid system, or it can be sent to another stage
or system for further
processing, including, but not limited to, another two-step or three-step
substance collection
system. a reverse osmosis unit, andior an ion exchanger. The portion of the
fluid that does not
pass through the three-step system's initial step substance collection device
250 along with a
portion of the particles rejected or prevented from passing through the three-
step system's
initial step substance collection device 250. i.e., reject and/or concentrate,
is directed to the
intermediate substance collection device 260 for at least one additional
processing step.
Preferably, this processing step includes, belt is not limited to: (1) using a
step-one recycle
loop 264 to establish a high velocity step-one reject recirculation stream
flow across the
upstream side st~rface(s) of the three-step system's initial step substance
collection device 250
so that the reject and/or concentrate (''reject") and the fluid form a step-
one reject
recirculation stream, which is carried by the step-one recycle loop 264; and
(2) divertin~~ a
portion of the step-one reject recirculation stream into a step-two reject
recirculation stream
carried by a step-two recycle loop 268 to establish a high velocity step-two
reject recirculation
stream flow across the upstream surfaces) of the three-step system's
intermediate step
substance collection device 260 having, preferably, at least one
ultraftltration membrane_ and.
preferably, by introducing precipitating agents andior by concentrating the
reject that is
contained in the diverted portion of the step-one reject recirculation stream.
and/or by the
selection of tile proper particle collection size rating, the intermediate
step suhstance
collection device 260 is used to collect the substances of interest on the
upstream surface; o-f~
each of its filter elements. Preferably, the ccmcentration of the reject in
the diverted portion of
the step-one reject recirculation stream is accomplished by directing this
stt°eatn to an
evaporator 650, a centrifuge 655, or to any other suitable concentrating
device, before
directing the concentrated fluid and/or concentrates to the intermediate step
substance.
collection device 260. Preferably, therefore, at this point in the sequential
filtering sequence,
a portion of the fluid will pass through the intermediate substance collection
device 260 as a
filtrate. (and/or permeate), and another portion of the fluid will pass across
the upstream side
surfaces of the intermediate substance collection device 260 and will remain
in the step-two
reject recirculation stream for further processing. To maintain the flows, the
velocity of the
29
CA 02429484 2003-05-23
fluid in the step-one recycle loop 264 is maintained through the use of a step-
one recycle loop
pump 266 and possibly a controller and/or the setting of valves and/or other
flow control
devices, and the velocity of the step-two recycle loop 268 is maintained
through the use of a
step-two recycle loop pump 276 and possibly a controller 278 andior the
setting of valves
and/or other flow control devices including. but not limited to, throttle
valves. The filtrate
(and/or permeate) from the intermediate substance collection device 26(1 is
then directed to
the step-one recycle loop 264 through conduit 275 and returned for another
pass through the
three-step system's initial step substance collection device 250 while a
portion of the step-two
reject recirculation stream is diverted fiom the stream and is further
processed by the three-
step system's final step substance collection device 270 through the use of at
least one
additional processing step. Preferably, this additional processing step
includes, but is not
limited to, diverting a portion of the step-two reject recirculation sta~eatn
flow carried by the
step-two recycle loop 268 into the step-tlu-ee substance collection flow path
290. which passes
through the three-step system's anal step substance collection device 270 at a
low flux. The
velocity and/or flux of the fluid through the three-step system's final step
substance collection
device 270 is maintained b~- a pump 380 and possibly a controller 382 andJor
the setting ol~
valves and/or other flow control devices including, but not limited to,
throttle valves, which
cause the filtrate from the three-step system's final step substance
collection device 27() to be
directed back to the step-two recycle loop 268 through conduit 286 for another
pass through
the tiu~ce-sicp systciri's internuediate step subsianc.e collection device 260
(or is optionally
directed back to the step one recycle loop 264 throu~~h conduits 275 and 285
for another pass
through the three-step system's initial substance collection device 250 or it
can be optionally
directed back to a previous stage through conduit 40(1). In the. manner and
for the reasons
previously described in association with the two-step system's final step
substance collection
device 200, the velocity or flux of the fluid passing through the three-step
system's final step
substance collection device 270 is maintained very low to maximize the solids
(-i.c..
substance) loading and the per pass efficiency of the three-step system's
final step substance
collection device 270. Optionally, however, as previously mentioned, a portion
of the fluid
and reject in the step-one reject recirculation stream may first be directed
to an optional
evaporator 650, a centrifuge 655, or to any other suitable concentrating
device, for
CA 02429484 2003-05-23
precipitation/concentration of the substance to be collected prior to the
fluid being directed to
the intermediate step substance collection device 260 and then to the final
step substance
collection device 270. Afterwards, the concentrated fluid and/or concentrates
from each
concentrating device are then preferably directed to the step-two (or second)
recycle loop 268
upstream of the intermediate step substance collection device 260. while the
distillate of an
evaporator 650 (or the corresponding clean stream of any other concentrating
device being
used) is preferably directed to the upstream side of the initial step
sLibstance collection device
250 and/or to a conduit 625 for release c:n~ reuse (if the distillate meets
purity criteriaj.
Preferably, the evaporator bottoms/concentrate and/or the distillate are
sufficiently cooled
after leaving the evaporator 65(1 and before being introduced back into the
present system. and
this cooling, if needed, can be accomplished through the use of any of a
variety of standard
cooling means including. but not limited to, condensers or heat exchangers.
[0048] In other words, the present method comprises having a fluid medium
source containing substances to be collected. The fluid medium is directed to
a first initial
step suL~stance collection device 150 of a two-step 1U collection system, or
250 of a three-step
S or 15 collection system; a portion of the fluid passes through this first
initial step substance
collection device, possibly for further processing usin~~ another two-step
and/or three-step
substance collection system 5 10, or 15, and/or an ion exchanger or reverse
osmosis unit 140.
The reject collected on the upstream side surface of this first initial step
substance collection
device 150 or 250 along with a portion of the fluid is carried by a first
recycle loop 164 or
264. In a three-step substance collection system, a portion of this first
recycle loop flow is
diverted to a second recycle loop 268 having an intermediate substance
collection device 260
(or optionally to an evaporator 650, a centrifuge 655, or to any other
suitable concentrating
device in order to concentrate the substance to he collected). A portion of
the reject collected
on the upstream side surface of this intermediate substance collection device
260 aloe ~~ with ct
portion of this fluid is carried by a second recycle loop 268 and is then
diverted to a lov,' flux
substance collection flow path 290, which directs the fluid and reject carried
in this i7ow-~ path
through the filtration medium of the final step substance collection device
270, which is able
to form a filter calve on its upstream side filter surface. Similarly, in a
two-step substance
collection system 10, a portion of the first recycle loop 164 flow is directly
diverted to a low
31
CA 02429484 2003-05-23
flux substance collection flow path 172 and through the filtration media of
the final step
substance collection device 200, which is able to form a filter cake on its
upstream side filter
surface. In either a two-step or a three-step (or more step) substance
collection system. the
filtrate and/or permeate from each collection device that is in sequence
v~~ith the iW tial step
substance collection device is~recycled back to the initial step substance
collection device of
their respective system, and/or is directed to a flow path associated with a
previous step's. or a
previous system's, substance collection devices) for further processing
through intra-stage
and/or inter-stage recycling, for example, but not as a limitation, by using
the conduit 400
shown in FIGS. 2 and 3. Additionally, in either a two-step 10 or a three-step
(or more step)
system 5 and/or 15, it is possible to inject or add precipitating agents
and/or other processing
chemicals at almost any location on the collection system. For example, but
not as a
limitation, precipitating agents can be added to the feed to the second
recycle loop 268 in a
three-step system through a conduit 412 as shown in FIG. 2 and 3. Also, as
previousl<<
mentioned, the reject from, and the fluid not passing through, the initial
step substance
collection device 1i0 or 250 may first be sent to an evaporator 6~0. a
centrifuge 6~~. or to
any other suitable concentrating device in order to concentrate the substances
to be collected
prior to being directed to a subseduent stage in the sequence of filtering
stages.
[0049] Preferably, the capability of baclcflushing the initial step collection
devices
and/or intermediate step collection devices will be provided as shown in FIGS.
1, 2 and 3.
Backflushing, as previously described, is performed to remove materials
deposited on the
upstream surfaces of the substance collection devices in order to maximize the
usable surface
area of the filtering elements and/or the filter. Backflushin« efficiency can
be improved by
using a pump, or by presstu~izing the baclcl7ushing l7uid, to produce a
reverse flow havin<,~ a
high velocity through the filter elements of the substance collection devices
durin<~
backflushing. Efficiency may be further improved by using the recycle loop to
form a high
velocity recircttlating reject stream flow across the upstream side surface of
the substance
collection device, which may be further eWanced by introducing air or ozone.
or any other
suitable gas, preferably under pressure. either into the baclcfl ush fluid or
into the i°ecirculating
reject stream. The recirculating reject stream, along with many of these other
enhancing
methods described herein, which can also be used with the presently described
embodiments.
CA 02429484 2003-05-23
improve backflushing effectiveness by increasing turbulent flow and, thereby,
causiry~ the
laminar flow layer across the surface of the filtering elements to be
decreased. This provides
a more effective cleaning, which increases the usable lifetime of the
backflushecl substance
collection devices. Additionally, the effectiveness of backflushing and/or
cleanin'1 of the
substance collection device's surfaces may be improved by introducing chemical
and/or
bacterial cleaning agents into the baelcflushing fluid, and/or chemical and/or
bacterial ~u~d/ol°
mechanical cleaning agents into the recirculating reject stream. which may
cause a more
effective cleaning of the particulate from the laminar flow areas of the
collection device.
Moreover, ultrasonic means can be used alone or in combination vr~ith the
above-described
cleaning methods, and, if the proper combination of cleaning methods for the
substances to be
collected, the fluid media, and/or the filter elements is a sed, the cleaning
results can be
effectively amplified. For example, but not as a limitation, the use of
ultrasound impacts on
or causes the formation of gas bubbles. which causes the colloids (even those
trapped by the
filter elements) to vibrate, and can increase the mechanical chemical and/or
bacterial
efficiency of the mechanical, chemical, and/or bacterial cleaning agents that
are used.
[0050) Preferably, to perform bacl:flushing, filtrate and/or permeate from a
initial
step and/or intermediate step collection device is stored in a haclcflushing
feed taW: 500, a
chemical hopper 515 and pump 516 can be used to add cleaning agents, and a
source of
pressurized gas 525 and/or a back flushin~~ pump 530 can be used for the
baclcflushin<~
purposes previously described. Additionally. besides usin~~ collection system
filtrate and/or
permeate for a source of backflushing fluid, demineralized and/or deionized
water and/or
other fluids outside the collection system, and/or gas/wat~r mixtLares cato
also be used to
remove particulate. Furthermore, the introduction of ozone can be used la
provide membrane
cleaning. especially when fouled by organic materials. 1-Iowever, since the
bacl<flush feed
tan: 500 can be filled with filtrate andior permeate from a substance
collection device, the
need for supplying demineralized and; or deionized water for back flushing is
reduced or
eliminated. The backflush feed tank 500 will feed baclcflush fluid through a
conduit 536 to
the downstream side of collection device being cleaned 150. 250, and/or 260
during the
baclcflush cycle. and after the baclcflush fluid passes through the collection
device bein'.a
backflushed, it can be collected in a backllush collection tank 600. The
contents of the
a,
CA 02429484 2003-05-23
backflush collection tank 600 can then be processed to remove suspended solids
or dissolved
materials. Generally, this is accomplished by using one of three optional
methods for feedings
the contents of the baclcflush collection tank 600 back to the system, as
shown with reference
to the system 10 of FIG. 1. Option One is to feed the contents of the
backflush collection tank
600 to the initial step recycle loop 164 (or 264). Option Two is to feed the
contents of the
backflush collection tank 600 to the final step collection flow path 172 (or
290). Option
Three is basically a batch-wise process option, in which the final step
substance collection
device 200 (or 270) is isolated from its system 10 (or ~ and/or 15) and is
used to form a fluid
loop with the baclcflush collection tank 600 so that the contents of the
backflush collection
tank 600 are recycled through the final step substance collection device 20U
(or 270) for as
long as the user desires. However, if desired, the contents of the collection
tank 600 may be
externally processed or disposed of as well. While these options are the
preferable methods
of processing the contents of the backflush collection tank 600, any other
suitable method can
also be used.
[0051] Generally. in operation. the substances collected on the final step
substance
collection device 200 or 270 will cause the pressure drop across the f nal
step suhstance
collection device 200 or 270 to increase. and. when the maximum allowable
differential
pressure drop across the device is reached. or the final step substance
collection device 20() or
270 is filled with substance, mdlor other limitin~~ criteria are reached, the
final step substanc-a
collection device 200 or 270 and/or its alter elements will be replaced with a
new or recycled
final step substance collection device 200 or 270. and/or filter elements.
Related to this, when
collecting radioactive contaminants. the final step substance collection
device 200 or 270 will
be replaced when the maximum allowahle radiation dose rate. activity level,
safe mass leveis_
and/oi° other limiting criteria are reached. Pi°eferably, prior
to rc;placement, the substances
collected and/or the collection device 200 or 27(1 will have excess fluid
removed as described
lZerein.
[0052] Preferable, after collecting the substances carried by the fluid,
excess fluids
are removed from the final step substance collection device 200 or 270. As
background for
fluid removal in the present two-step or the three-step (or more step)
substance collection
,4
CA 02429484 2003-05-23
system, the filter calve forming filter is preferably contained within the
final step substance
collection device 200 or 270, which can be operated at norn~al system
pressures v~~hile
attached to the present invention system, which- in turn, allows for fluid
removal through
pressurization of the final step substance collection device 200 or 270. This
is in contrast to
those prior art systems that use filters and collection devices that cannot
withstand
pressurization, and which obtain fluid removal by suctioning off the fluids at
pressures belo«~
atmospheric pressure. Therefore, since the present invention system can be
pressurized. it can
be operated at differential pressures that are much higher than those that can
be used for
systems that rely on suction-type dewatering. This provides for a higher
solids loading, i.e., a
higher concentration of solids, on the present invention's filter elements
and/or for quicker
fluid removal.
[U053] Preferably, the fluid removal process used with the present invention
can
be accomplished by using pressurized air, or some other suitable, and
preferably inert, ~~as,
which Applicant believes is more effective and/or eff cient than the standard
practice of
suction dewatering. The use of pressurized fluid removal also results in: (1)
the elimination
of the equipment required for st,tction-type dewatering, which lowers the
space required for
the present invention; (2) less maintenance being required; (3) faster
operations, v.~=hich
decreases the amount and/or magnitude of exposure that a worker would have to
radioactive,
toxic. and/or hazardous materials t;in comparison to standard suction-type
dewaterin'T): (4) a
higher substance of interest concentration. and (~) cost savings in equipment
and labor. The
fluid removal processes used with the present invention can also be performed
~ind/or
enhanced through tine introduction of expendable materials such as expandable
foams into anv
of the void spaces in order to displace the fluids. or thrc~u~~h the filling
of such void spaces
with adsorbent materials and/or disposable materials including waste products.
During or
after fluid removal, the substances collected by the. final step substance
collection device 200
or 270 can be processed by backflushing. if appropriate, to remove the
substances Pram the
collection device so that it may be reused. or the collected substances can be
processed by
using prior art methods, or they may be disposed of directly along with the
final step
substance collection device 200 or 270, if desired.
3>
CA 02429484 2003-05-23
[0054] Referring to FIG. 4, preferably, in operation of the fluid removal
process.
the substance collection fluid flow path to the final step substance
collection device 200 or
270 is isolated by shutting valve Vl, which may be a three-way valve, and the
final step
substance collection device's filtrate flow path is isolated by shutting valve
V2, and the first
fluid removal flow path is opened (preferably, the first fluid removal flow
path"s conduit is
attached to the final step substance collection device's filtrate flo«~ path
between an isolation
valve V2 and the final step substance collection device 200 or 270). A source
of pressurized
gas is then placed in-service by opening valve V4, and the pressurized gas is
used to
pressurize the headspace of the final step substance collection device 200 or
270 to displace a
portion, or all, of the fluids contained within the substance collection
device 200 or 270.
When evidence is obtained that gas is entering the first fluid removal flow
path, the second
fluid removal flow path is opened by opening valve V~ and the first fluid
removal flow path is
then isolated by shutting valve V3. The conduit for the second fluid removal
flow bath is
attached directly to a fluid removal conduit contained within substance
collection device 200
or 270, and is preferably connected to a separate fluid removal filter on or
near the bottom of
the substance collection device 200 or 270, for example a horizontal sheet
filter may be used.
The fluid removal process is terminated when gas is detected entering the
second fluid
removal flow path conduit. A5 ShOwll 117 FICT. 4, tile fluid removed from the
final step
substance collection device 200 or 27() is preferably directed to the
baclcflush collection tank
60u; however, this fluid can be directed to any other suitable location
including. but not
limited to, facility drains. Performing fluid removal in this wav provides the
user with a
higher concentration of the substances of interest, the processin~~ of a
greater volume of fluid
containing the same concentratiolo of such substances, and/or a much duicl:er
and/or more
efficient fluid removal. Also as shown in hIG. ~ arc two pumps 60; and 610.
Pump 605 is a
baclcflush recirculation pump 605 and is normally used to reprocess the
contents of the
baclcflush collection tanlc 600, while ptunp 610 is an optional i7uid removal
vacutun pump
610, which can be used to remove fluids from the final step substance
collection device 20() or
270 by suctioning them from the final step substance collection device 200 or
270.
[005] Preferably, the final step substance collection device 200 or 270 is
carried
within an optional Multi-Purpose Container 70 or 700 w~lule attached to the
present invention
s6
CA 02429484 2003-05-23
system. Preferably, the Multi-Purpose Container 70 or 700 is dimensioned to
readily carry
the final step substance collection device 200 or 270 and is fabricated of a
material suitable
for the application in which the present invention system is being used. For
example. when
used to receive radioactive wastes the Multi-Purpose Container 70 or 700, may
be fabricated
of a cross-linked polyethylene suitable for handling. transporting, and/or
disposing of such
waste. Preferably. the Multi-Purpose Container 70 or 700 is a container that
is certified to
meet the industry-based and/or governmental requirements imposed on containers
of this type
when they are used for the purposes described herein. Additionally, the Multi-
Purpose
Container 70 or 700 ("MPC") is a combination processing enclosure, transport
container,
and/or disposal container for the final step substance collection device 20U
or 270 and~'or the
filter cake and the filter cake forming filter used in the final step
substance collection device
200 or 270, and provides the present invention system with expanded processing
and/or fluid
removal features over the prior art.
[0056] The design of the present system not only a llov-s for pressurized
fluid
removal of a possibly disposable substance collection device while still being
attached to the
present invention system, which tray be carried within a .MPC', but it also
allows i-or the
introduction of expanding agents such as foams instead of gas. The possible
use of foam,
introduced into the headspace at the top of the substance collection device
200 or 27(). will.
due to its expansion, squeeze fluids out of the filter cake and/or the
substance collection
device 200 or 270, which can provide a very efficient method of fluid removal.
Related to
this, the present invention can also use a;~ents, similar to those used in
fire extinguishers.
v,~hiclv can be introduced into the substance collection device 200 or 270 and
then activated at
the end of the substance collection device's 200 or 27U lifecycle. This would
allow a
substance collection device 200 or 270 to be able to undergo fluid removal in
circumstances
where the use of suction dewatering andior pressurized fluid removal equipment
is
unavailable and/or impractical. Preferably, if the collected substances are
destined for
disposal, the substance collection device 200 or 270 is dimensioned to be
carried within the
MPC 70 or 700, and. to reduce costs (especially disposal costs) the void
spaces within the
substance collection device 200 or 270. and/or between the substance
collection device 200 or
270 and the MPC 70 or 700, can be filled with a void filling material. which
is preferably an
i7
CA 02429484 2003-05-23
inert material that can flow into the void such as used resins. As a result,
since a
characteristic of the filter cake is that it is practically devoid of excess
fluid and other volume
increasing constituents (other than the substances of interest), the
substances collected and/or
the collection device 200 or 270 could possibly be prepared for disposal or
recovor5~ ~.vithout
the need for solidification and/or thermal processing. And. as previously
described, all of the
fluid removal processes, aside from transportation and disposal, can be done
while the
substance collection device 200 or 270 and/or the MPC 70 or 700 are in place
on the present
invention system and on-site, and not as a separate external process. On the
other hand, the
present invention's flexibility also allows for all of the processes, methods,
techniques, andior
portions of the present invention system as explicitly or implicitly described
her ein to be
performed andlor provided individually on a stand-alone basis as well as in
the combinations
explicitly or implicitly described herein. Importantly, the method and manner
in which
substances are collected in the present invention provides for the recovery of
substances that
previously could not be efficiently and/or economically recovered by other
svstems_
especially those using drying processes: thereby, enabling the recovery of
these substances for
the first time. For example, but not as a limitation, bin-compounds that
cannot be thermall~~
treated, e.g., by freeze-drying or evaporation, may he recoverable with the
present invention
system.
[0057] As examples of the system's flexibility, but not as a limitation. the
present
invention system can be used for a variety of applications including, but not
limited to.
enhancing chen ~ical reactions, such as in the precipitation of dissolved
metals. and providing
an alternative to ''fluid bed l~rocessin ~~'~ and its associated risks. which
can include the release
of andior the exposure to fine toxic andior radioactive materials. :~s
background. and
generally. when a precipitating agent (or p rc;cipitation reagent)-whether
sulfide, hydroxide.
or phosphate based-is introduced into a fluid. the precipitation process
generally proceeds in
two stages. The first stage is nucleation, wherein ultl~afine, stable
crystalline structures are
formed. These structures. in some cases, such as hydroxide precipitation, are
virtually
impossible to filter and cannot undergo effective fluid removal processing
(e.g.. dewatering).
The resulting stable suspension of crystallites can be broken down by
digesting the suspension
thermally for an amount of time that can last ani~where between several
minutes to more than
s8
CA 02429484 2003-05-23
several hours, depending on the characteristics and the constituents of the
starting suspension.
During this thermal processing, some of the formed crystallites dissolve and
re-precipitate
forming seed particles. which are able to grow into larger, easier to collect,
particles that can
filtered from the suspension and can then undergo fluid removal for
dewatering). The second
stage is a growth stage, in which further precipitation further grows the
nucleate seed
particles, and, consequently, results in much larger precipitates, v~~hich
allows for a much
more effective filtering, and/or fluid removal (or dewatering).
[0058] One way to '"by-pass" nucleation is to add "seed" particles of the
final
compound (i.e., the substance intended to be collected) such that the
precipitates hit the
growth phase directly. This is particularly important for hydroxide
precipitation where rapid
nucleation normally precludes this process from using fluid removal processing
( or
dewatering) due to the stable suspension formation. Importantly. this "bv-
pass" can be
accomplished in the present invention system by injecting precipitants) into
the present
invention's recycle loop or by injecting the precipitants) into the
precipitating agents)
holding tank 100, preferably under agitation_ which would allow seeds to form
in tile holding
taut 100, and then feeding a portion of the seeded contents of the holding
tank 100 to the
recycle loop 164 through conduit 101, in either case causin~l a sufficient
amoLmt of seed
particles to be inti°oduced into the system. After a sufficient
concentration of seed particles is
obtained in the recycle loop 164, the fluid containing the substances ~fi
interest ~.~~il_l hr~
introduced to the recycle loop 164 from another fluid source. which is
preferably holding tank
110; however, any other suitable source of fluid could be used. The substance
of interest will
them be removed from this fluid and collected by the final step substance
collection device
200 and/or 270. This is made possible because the design of the system, with
its high
turbulence (from form drag. if from no other source. and/or iu°om its
high flow rates) will give
good mixing and promote an even precipitant concentration, which would enable
even the use
of the hydroxide reagents in recovery operations and would achieve the type of
control over
the concentration field normally only found in tluidized beds - except that
with the present
invention system solids entrainment would not be a problem. whereas
entrainment is a
troublesome issue for fluidized beds.
s9
CA 02429484 2003-05-23
[0059 In this regard, while fluidized beds generally can be said to have Sufi-
iciest
control of temperature and/or composition fields, which, arguably, gives them
better overall
process control then other prior art systems, the present invention system is
an improvement
over fluidized beds. For example, in fluidized beds, process liquids/fluids
are filtered for
solids recovery prior to discharge, and product gases may be filtered,
condensed, scrubL~ed. or
otherwise processed for product recovered (oftentimes the off-gas train may be
as simple as a
train of high efficiency cyclones, possibly, with a baghouse as a backup). In
processing
radioactive or biologically active materials, however. the activity of the
contaminants
(particularly in the case of radioactive materials) significantly lowers the
limits of detection.
This causes a significant and expensive inci°ease in the effluent
treatment system required for
the operation of an environmentally safe fluidized bed system. On the other
hand, the use of
the present invention system, with all of the discharge coming as
filtrate/permeate from the
initial step substance collection device 150, virtually eliminates the need
for an extensive
effluent treatment system while providing the benefits of improved process
control. In
summary, whereas the present invention system's filtration characteristics
provide the
opportunity to both improve the quality of all f7uid/liquid discharge streams
and minimize the
volume of an y secondary waste that is generated, the present system's
flexibility also
establishes the present invention system as a chemical reactor that, as a
example. provides a
very effective precipitation step in the case of the present invention system.
Furthermore, due
to its comparable process control characteristics lut without the problem of
solids
entrainment, the present invention system offers an effective alternative to
processing by
fluidized beds.
[0060 Even though the present invention system does not require the use of
thermal
processing to prepare the substances collected by the final filter for
recovery or disposal. as
another example of the present invention system's flexibility, but not as a
limitation. the
present invention system can be used in applications in which fluid removal
(or dewaterin'~) is
inadequate, for example, in cases where higher-level waste forms are
collected, such as some
radioactive wastes, which may require the solidification of such waste forms.
In this regard,
and optionally, the present invention system also can be used for reactor
waste form
stabilization, and for the stabilization of other wastes including, but not
limited to. other
CA 02429484 2003-05-23
radioactive, hazardous, toxic, and/or a:my other similar wastes. One reason
for this, as
previously described, is that the final step substance collection device 200
or 270 can be used
as the final disposal receptacle for the collected substance, e.g.,
radioactive waste, (with or
without the use of an MPC 70 or 700), and. therefore, can be used as a base
for a stabilization
system. Preferably, when used for such applications, the substances collected
in the final step
substance collection device 200 or 270 can forni a composition that is
compatible with
solidification ancfor vitrification. Preferably. this can be accomplished by
injecting., in the
manner previously described with respect to introducing precipitating agents
into the system,
a reagent into the recycle loop 164, such as a grout or a silicate-based
material (e.g., sodium,
and/or other silicate-based compounds including sand can be used as a filler
and/or a glass
former). which would be particularly useful with oxide or hydroxide particles
in order to bind-
up the contaminants (i.e., waste). By Llslll'~ the silicates and sand as glass
formers, heat would
be applied until solidification and/or vitrification occurs. Preferably,
heating of the waste
and/or the other materials present is accomplished by using electrical
resistance elements
and/or electrodes with the final step substance collection device 200 or 270
to supply .joule
heating to the contents of the final step substance collection device 2(10 or
270, or througf~ the
introduction of microwave energy. In the case of using microwave energy. the
microwave
energy frequency would be tuned to optimize coupling with any oxide, hydroxyl,
silicate or
other receiving compound in the mixture. While these are the preferred methods
for
stabilizing tire collected substances, any other suitable chemical and/or
agent can he used to
form the composition to be solidif ed and/or vitrified, and/or any other
source of heat can be
used. Furthermore, the heat source may be integrated into or used in
combination with a
modified MPC 71 and/or 701 (as shown in FIG. 5) and/or into the final step
substance
collection device 200 or 27(l. Referring to FIG. ~, for example. and
preferably, the modified
MPC 71 and/or 701 will carry the final step substance collection device 200 or
27(?. «,hich
will be attached to the system, and may have annular heating elements 72
located on or in
contact with the modified MPC's 71 tmd/or 70I interior surface, which then
ma~~ be used to
effectively conduct heat into the final step substance collection device 200
and/or 270. After
solidification andior vitrification of the collected substance, the final step
substance collection
device 200 and/or 270 and, therefore, the collected substance can be removed
from the system
41
CA 02429484 2003-05-23
and the modified MPC 71 and/or 701, and then secured within a standard MPC 70
md/or 270
for transportation and disposal. With respect to using microwave energy, a
modification
allowing for a single or a mufti-port magnetron or other source of microwave
energy can be
incoporated into the design so that it is an integral part of or used in
combination with a
modified MPC 71 and/or 701. For example, and preferably, a microwave
generating unit 73
attached to or used in combination with a modified MPC 71 and/or 701 can
direct microwave
energy into the tonal step substance collection device 200 and/or 270, which
will be
constructed of a material that will allow the microwave energy to pass through
the material
with no, or very little, absorption of the microwave energy, such as some
glasses, ceramics,
and plastics (also as shown in FIG. 5; however, a.nd preferably though, both
sources of heat
are not simultaneously attached to and/or in contact with the modified MPC 71
and/or 271).
After solidification and/or vitrification of the collected substance, the
final step substance
collection device 200 and/or 270 and, therefore, the collected substance can
be removed iron ~
the system and from the modified MPC 71 and/or 701., and then secured within a
standard
MPC 70 and/or 270 for transportation and disposal. ( While these are the
preferred methods
for solidifying and/or vitrifying the collected substance and for disposing of
the collected
substance and the final step substance collection device 200 and/or 270, any
other sl.iitable
method for solidifying andior vitrifying, and disposing of the collected
substazxe can be used
including, but not limited to, aiiy other type of energy suitable for
transmission from the
modified MPC 71 and/or 701, the standard llAfC 7(1 and/or 70U, and/or for the
transnnission of~
the energy directly into the final step suL~stance collection device 200
and/or 270. for example.
but not as a limitation, by inserting. preferably disposable. electrodes into
the fnul step
substance collection device 200 and/or 270 andior into the collected
substances.) Since very
high temperatures may he required to vitrii'y the substances collected. the
materials used to
fabricate the final step substance collection device 200 and/or 270 (and~'or
the MfC 70 or 700)
would have to be compatible with the temperattues used. For example, but not
as a limitation.
high temperature polymers and/or steels may be used. By being able to use the
present
invention system in this manner makes the present invention system very
appealing to those
entities producing higher activity wastes, such as those found on DOE sites,
for which simple
fluid removal (or dewatering) is inadequate.
42
CA 02429484 2003-05-23
[0061] It will be apparent to those skilled in the art of fluid processin~~
that many
modifications and substitutions may be made to the foregoing detailed
description without
departing from the spirit and scope of the present invention, which is defined
by the appended
claims.
:13
