U.S. patent application number 12/799582 was filed with the patent office on 2011-02-17 for ballasted anaerobic system and method for treating wastewater.
Invention is credited to Steven Woodard.
Application Number | 20110036771 12/799582 |
Document ID | / |
Family ID | 44861855 |
Filed Date | 2011-02-17 |
United States Patent
Application |
20110036771 |
Kind Code |
A1 |
Woodard; Steven |
February 17, 2011 |
Ballasted anaerobic system and method for treating wastewater
Abstract
A ballasted anaerobic system for treating wastewater including
at least one anaerobic treatment reactor. A weighting agent
impregnation subsystem is configured to mix weighting agent with
the biological flocs to form weighted biological flocs to create a
weighted anaerobic sludge blanket in the at least one anaerobic
treatment reactor. A weighting agent recovery subsystem is
configured to recover the weighting agent from excess sludge and
reintroduce the weighting agent to the weighting agent impregnation
subsystem.
Inventors: |
Woodard; Steven;
(Cumberland, ME) |
Correspondence
Address: |
Iandiorio Teska & Coleman
255 Bear Hill Road
Waltham
MA
02451
US
|
Family ID: |
44861855 |
Appl. No.: |
12/799582 |
Filed: |
April 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12584545 |
Sep 8, 2009 |
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12799582 |
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12008216 |
Jan 9, 2008 |
7695623 |
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12584545 |
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60879373 |
Jan 9, 2007 |
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60994553 |
Sep 20, 2007 |
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Current U.S.
Class: |
210/608 ;
210/173; 210/194 |
Current CPC
Class: |
C02F 2305/12 20130101;
C02F 1/36 20130101; C02F 1/56 20130101; C02F 3/2846 20130101; C02F
1/488 20130101; C02F 1/5236 20130101; C02F 1/38 20130101 |
Class at
Publication: |
210/608 ;
210/194; 210/173 |
International
Class: |
C02F 3/28 20060101
C02F003/28 |
Claims
1. A ballasted anaerobic system for treating wastewater comprising:
at least one anaerobic treatment reactor; a weighting agent
impregnation subsystem configured to mix weighting agent with the
biological flocs to form weighted biological flocs to create a
weighted anaerobic sludge blanket in the at least one anaerobic
treatment reactor; and a weighting agent recovery subsystem
configured to recover the weighting agent from excess sludge and
reintroduce the weighting agent to the weighting agent impregnation
subsystem.
2. The system of claim 1 in which the weighted anaerobic sludge
blanket is configured to treat the wastewater and provide a treated
effluent.
3. The system of claim 1 in which the weighting agent impregnation
subsystem includes an impregnation tank and at least one mixer.
4. The system of claim 3 in which the weighting agent impregnation
subsystem includes a storage subsystem for storing virgin weighting
agent and dispensing the virgin weighting agent into the
impregnation tank.
5. The system of claim 1 in which the weighting agent impregnation
subsystem includes a venturi mixer/eductor.
6. The system of claim 1 in which the weighting agent recovery
subsystem includes a separator subsystem for separating the
weighting agent from the biological flocs.
7. The system of claim 6 in which the separator subsystem includes
a shear mill.
8. The system of claim 6 in which the separator subsystem includes
a centrifugal separator.
9. The system of claim 6 in which the separator subsystem includes
an ultrasonic separator.
10. The system of claim 6 in which the separator subsystem includes
a shear mill and a wet drum magnetic separator.
11. The system of claim 6 in which the separator subsystem includes
a shear mill and a centrifugal separator.
12. The system of claim 6 in which the separator subsystem includes
an ultrasonic separator and a wet drum magnetic separator.
13. The system of claim 6 in which the separator subsystem includes
an ultrasonic separator and a centrifugal separator.
14. The system of claim 7 in which the shear mill includes a rotor
and a stator, wherein the rotor and/or the stator include slots
sized as to optimize separation of weighting agent from the
weighted biological flocs.
15. The system of claim 1 in which a majority of the weighting
agent has a particle size less than about 100 .mu.m.
16. The system of claim 1 in which a majority of the weighting
agent has a particle size less than about 40 .mu.m.
17. The system of claim 1 in which a majority of the weighting
agent has a particle size less than about 20 .mu.m.
18. The system of claim 1 in which said weighting agent includes
magnetite.
19. The system of claim 2 in which the weighted biological flocs
enhance the quality of the treated effluent by reducing suspended
solids and associated contaminants therein.
20. The system of claim 1 further including a wasting subsystem for
wasting excess sludge to control the population of
microorganisms.
21. The system of claim 18 in which the capacity of the system is
increased by increasing the concentration of microorganisms solids
in the anaerobic treatment reactor by reducing the amount of the
sludge wasted by the wasting subsystem.
22. A ballasted anaerobic method for treating wastewater, the
method comprising: a) receiving influent wastewater in at least one
anaerobic treatment reactor; b) forming biological flocs in the at
least one anaerobic treatment reactor; c) impregnating weighting
agent into the biological flocs to form weighted biological flocs
to create a weighted anaerobic sludge blanket; and d) recovering
weighting agent from the weighted biological flocs to reintroduce
the weighting agent to step c).
23. The system of claim 22 further including the step of directing
the wastewater through the weighted anaerobic sludge blanket to
provide a treated effluent.
24. The method of claim 22 further including the step of separating
the weighting agent from the weighted biological flocs.
25. The method of claim 22 further including the step of collecting
the weighting agent and recycling the weighting agent to step
c).
26. The method of claim 22 further including the step of providing
weighting agent in which the majority of the weighting agent has a
particle size less than about 100 .mu.m.
27. The method of claim 22 further including the step of providing
weighting agent in which the majority of the weighting agent has a
particle size less than about 40 .mu.m.
28. The method of claim 22 further including the step of providing
weighting agent in which the majority of the weighting agent has a
particle size less than about 20 .mu.m.
29. The method of claim 22 further including the step of enhancing
the quality of the treated effluent by reducing suspended solids
and associated contaminants therein.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/584,545, filed Sep. 8, 2009, which is a
continuation-in-part of U.S. patent application Ser. No.
12/008,216, filed Jan. 9, 2008, now U.S. Pat. No. 7,695,623, issued
Apr. 13, 2010, entitled "System and Method For Enhancing An
Activated Sludge Process", which claims benefit and priority of
U.S. Provisional Application Ser. No. 60/879,373, filed Jan. 9,
2007, entitled "Process For The Biochemical Treatment Of
Wastewater", and also claims benefit of and priority to U.S.
Provisional Application Ser. No. 60/994,553, filed Sep. 20, 2007,
entitled "A Process For Enhanced Biochemical Treatment Of
Wastewater", all of which are incorporated by reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to a ballasted anaerobic system and
method for treating wastewater.
BACKGROUND OF THE INVENTION
[0003] One method of treating wastewater, such as wastewater from
ethanol plants, breweries, pharmaceutical plants, food processing
plants, pulp and paper facilities, and the like, is to use an
anaerobic treatment reactor. The anaerobic treatment reactor is
typically seeded with a population of microorganisms that ingest
contaminants in the influent wastewater to form biological flocs or
granules (hereinafter "biological flocs"). Wastewater is typically
fed into the bottom of the anaerobic treatment reactor and
microorganisms consume the waste therein and from biological flocs.
After a sufficient startup period, the biological flocs form an
anaerobic sludge blanket near the bottom of the anaerobic treatment
reactor.
[0004] In operation, wastewater is fed into the bottom of the
anaerobic treatment reactor and flows upward through the anaerobic
sludge blanket bringing the wastewater in contact with the
microorganisms that consume the waste therein. The treated
wastewater then flows over the weir of the anaerobic treatment
reactor as clean effluent.
[0005] Conventional anaerobic treatment reactor systems have a
limited difference in the specific gravity between the anaerobic
sludge blanket and the influent wastewater. Therefore, if the flow
rate of the influent wastewater is too high, the limited specific
gravity difference can cause the sludge blanket to become diffuse.
The result may be an elevated loss of microorganisms over the weir
which can result in compromised treatment efficiency and system
capacity.
BRIEF SUMMARY OF THE INVENTION
[0006] This invention features a ballasted anaerobic system for
treating wastewater including at least one anaerobic treatment
reactor. A weighting agent impregnation subsystem is configured to
mix weighting agent with the biological flocs to form weighted
biological flocs to create a weighted anaerobic sludge blanket in
the at least one anaerobic treatment reactor. A weighting agent
recovery subsystem is configured to recover the weighting agent
from excess sludge and reintroduce the weighting agent to the
weighting agent impregnation subsystem.
[0007] In one embodiment, the weighted anaerobic sludge blanket may
be configured to treat wastewater and provide a treated effluent.
The weighting agent impregnation subsystem may include an
impregnation tank and at least one mixer. The weighting agent
impregnation subsystem may include a storage subsystem for storing
virgin weighting agent and dispensing the virgin weighting agent
into the impregnation tank. The weighting agent impregnation
subsystem may include a venturi mixer/eductor. The weighting agent
recovery subsystem may include a separator subsystem for separating
the weighting agent from the biological flocs. The separator
subsystem may include a shear mill. The separator subsystem may
include a centrifugal separator. The separator subsystem may
include an ultrasonic separator. The separator subsystem may
include a shear mill and a wet drum magnetic separator. The
separator subsystem may include a shear mill and a centrifugal
separator. The separator subsystem may include an ultrasonic
separator and a wet drum magnetic separator. The separator
subsystem may include an ultrasonic separator and a centrifugal
separator. The shear mill may include a rotor and a stator, wherein
the rotor and/or the stator includes slots sized as to optimize
separation of weighting agent from the weighted biological flocs. A
majority of the weighting agent may have a particle size less than
about 100 .mu.m. A majority of the weighting agent may have a
particle size less than about 40 .mu.m. A majority of the weighting
agent may have a particle size less than about 20 .mu.m. The
weighting agent may include magnetite. The system may include a
wasting subsystem for wasting excess sludge to control the
population of microorganisms. The capacity of the system may be
increased by increasing the concentration of microorganisms solids
in the anaerobic treatment reactor by reducing the amount of the
sludge wasted by the wasting subsystem. The weighted biological
flocs may enhance the quality of the treated effluent by reducing
suspended solids and associated contaminants therein.
[0008] This invention also features a ballasted anaerobic method
for treating wastewater, the method including the steps of: a)
receiving influent wastewater in at least one biological reactor,
b) forming biological flocs in the at least one anaerobic treatment
reactor, c) impregnating weighting agent into the biological flocs
to form weighted biological flocs to create a weighted anaerobic
sludge blanket, and d) recovering weighting agent from the weighted
biological flocs to reintroduce the weighting agent to step c).
[0009] In one embodiment, the method may include the step of
directing the wastewater through the weighted anaerobic sludge
blanket to provide a treated effluent. The method may include the
step of separating the weighting agent from the weighted biological
flocs. The method may include the step of collecting the weighting
agent and recycling the weighting agent to step c). The method may
further include the step of providing weighting agent in which the
majority of the weighting agent has a particle size less than about
100 .mu.m. The method may further include the step of providing
weighting agent in which the majority of the weighting agent has
having a particle size less than about 40 .mu.m. The method may
further include the step of providing weighting agent in which the
majority of the weighting agent has having a particle size less
than about 20 .mu.m. The method may further include the step of
enhancing the quality of the treated effluent by reducing suspended
solids and associated contaminants therein.
[0010] The subject invention, however, in other embodiments, need
not achieve all these objectives and the claims hereof should not
be limited to structures or methods capable of achieving these
objectives.
[0011] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] Other objects, features and advantages will occur to those
skilled in the art from the following description of a preferred
embodiment and the accompanying drawings, in which:
[0013] FIG. 1 is a schematic side-view of one embodiment of the
ballasted anaerobic system for treating wastewater of this
invention;
[0014] FIG. 2A is a schematic side-view showing in one example of a
weighted sludge blanket formed at the bottom of the anaerobic
treatment reactor shown in FIG. 1;
[0015] FIG. 2B is a schematic side-view of the system for treating
wastewater shown in FIGS. 1 and 2A depicting one example of an
effluent recycling line and gas collectors;
[0016] FIG. 3 is a microscopic photograph showing one example of
weighting agent impregnated into biological flocs to form weighted
biological flocs in accordance with this invention;
[0017] FIG. 4 is a schematic side-view showing another embodiment
of the weighting agent impregnation subsystem shown in FIG. 1;
[0018] FIG. 5A is a schematic side-view of one embodiment of the
separator shown in FIG. 1;
[0019] FIG. 5B is a schematic top view showing one example of slots
in the rotor and stator of the shear mill shown in FIG. 5A;
[0020] FIG. 5C is a three-dimensional view of one embodiment of the
shear mill in FIG. 5A;
[0021] FIG. 6 is a three-dimensional front-view of another
embodiment of the separator shown in FIG. 1; and
[0022] FIG. 7 is a three-dimensional front-view of yet another
embodiment of the separator shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Aside from the preferred embodiment or embodiments disclosed
below, this invention is capable of other embodiments and of being
practiced or being carried out in various ways. Thus, it is to be
understood that the invention is not limited in its application to
the details of construction and the arrangements of components set
forth in the following description or illustrated in the drawings.
If only one embodiment is described herein, the claims hereof are
not to be limited to that embodiment. Moreover, the claims hereof
are not to be read restrictively unless there is clear and
convincing evidence manifesting a certain exclusion, restriction,
or disclaimer.
[0024] There is shown in FIG. 1 one embodiment of ballasted
anaerobic system 10 for treating wastewater of this invention.
System 10 includes at least one anaerobic treatment reactor 12,
e.g., a bulk volume fermenter (BVF) treatment reactor, an up-flow
anaerobic sludge blanket (UASB) treatment reactor, an internal
circulation (IC) treatment reactor, an anaerobic contactor, a
continuous stirred reactor, or similar type reactor. Anaerobic
treatment reactor 12 receives flow of influent wastewater 14 by
line 16. Anaerobic treatment reactor 12 is preferably covered as
shown at 13 to create an anaerobic environment therein. Influent
wastewater 14 is typically high strength wastewater from ethanol
plants, breweries, pharmaceutical plants, pulp and paper
facilities, or any similar type facilities or plants. Influent
wastewater 14 is typically fed into bottom 15 of anaerobic
treatment reactor 12 by line 16 and flows in an upward direction,
as shown by arrows 17. Anaerobic treatment reactor 12 is preferably
seeded with population of microorganisms which promotes growth of
biological flocs 23. After a sufficient startup period, sludge
blanket 18 forms near bottom 15 of anaerobic treatment reactor
12.
[0025] To overcome the problems discussed in the Background section
above, system 10 includes weighting agent impregnation subsystem 26
which impregnates biological flocs 23 to form weighted biological
flocs 25, FIG. 2A, to create weighted anaerobic sludge blanket 19.
Weighting agent impregnation subsystem 26, FIGS. 1 and 2A, in one
embodiment, includes impregnation tank 28 and mixer 30 which
receives biological flocs from anaerobic sludge blanket 18, FIG. 1,
and/or from weighted anaerobic sludge blanket 19, FIG. 2A, by line
32. Impregnation tank 28 also preferably receives virgin weighting
agent 33, e.g., from feed hopper 34 by line 36, and/or recycled
weighting agent 38 from weighting agent recovery subsystem 74
(discussed below). Mixer 30 mixes the biological flocs with virgin
weighting agent 33 and/or with recycled weighting agent 38 in
impregnation tank 28 to impregnate the weighting agent into the
biological flocs to form weighted biological flocs 25. In one
example, mixer 30 utilizes a mixing energy which is sufficient to
impregnate the weighting agent into biological flocs to form
weighted biological flocs. FIG. 3 shows a microscopic view of one
example of weighting agent 33, 38 impregnated into biological flocs
23 to form weighted biological floc 25. The weighted biological
flocs are then sent back to anaerobic treatment reactor 12 by line
37 and/or line 37' connected to line 16 to form weighted anaerobic
sludge blanket 19, FIG. 2A.
[0026] In operation, influent wastewater 14 is fed into bottom 15
of anaerobic treatment reactor 12 by line 16 and flows upward
through weighted anaerobic sludge blanket 19 bringing the
wastewater in contact with the microorganisms that consume the
waste therein to provide treated effluent 50 which flows over weir
27. In one design, anaerobic treatment reactor 12, FIG. 2B, may
include weirs 60 and 62 which treated effluent 50 flows over.
Anaerobic treatment reactor 12 may also include one or more gas
collectors 64, 66, and 68 coupled to line 70 which remove methane,
carbon dioxide, and other gases generated by the anaerobic process
of system 10 discussed herein. Treated effluent 50 may be recycled
by line 41 to line 16 to maintain a constant upflow velocity in
anaerobic treatment reator 12, e.g., as shown by arrows 17.
Recycling treated effluent 50 may also be used to adjust the flow
rate of the influent in line 16.
[0027] Increasing the density of weighted anaerobic sludge blanket
18, FIG. 1, to form weighted anaerobic sludge blanket 19, FIG. 2A,
creates a significant difference between the specific gravities of
the influent wastewater 14 and weighted anaerobic sludge blanket
19. The result is system 10 can accommodate higher loading rates
(flow rate/reactor size) of influent wastewater while preventing
weighted sludge blanket 19 from becoming diffuse. Therefore, system
10 is more efficient and effective than conventional anaerobic
treatment reactor systems. The weighted biological flocs in
weighted anaerobic sludge blanket 19 also improve the quality of
the treated effluent by reducing suspended solids and associated
contaminants therein.
[0028] In one embodiment, the weighting agent may be magnetite, or
any similar type weighting agent or magnetically separable
inorganic material known to those skilled in the art which
increases the density of the biological flocs. In one example, the
majority of the weighting agent particles have a size less than
about 100 .mu.m. In other examples, the majority of weighting agent
particles has a size less than about 40 .mu.m, or the majority of
particle size of the weighting agent may be less than about 20
.mu.m.
[0029] Weighting agent recovery subsystem 74 preferably includes
separator 78 which recovers the weighting agent from the excess
weighted biological flocs in line 76 and reintroduces (recycles)
the weighting agent to weighting agent impregnation subsystem 26.
Weighting agent recovery subsystem 74 may include recovery
subsystem 83, e.g., a wet drum magnetic separator or similar type
device, which recovers the excess weighted biological flocs
processed by separator 78. Recovery subsystem 83 reintroduces
recovered weighting agent 38 to weighting agent impregnation
subsystem 26.
[0030] System 10 also preferably includes wasting subsystem 85
which wastes the excess sludge in line 76 generated by weighting
agent recovery subsystem 74 by line 87 to control the population of
microorganisms in anaerobic treatment reactor 12. In one example,
the capacity of system 10 may be increased by increasing the
concentration of microorganisms in weighted anaerobic sludge
blanket 19 by reducing the amount of sludge wasted by wasting
subsystem 85.
[0031] System 10, FIG. 1, may also utilize weighting agent
impregnation subsystem 26', FIG. 4, where like parts have been
given like numbers. In this example, weighting agent impregnation
subsystem 26' includes venturi mixer/eductor 27 with nozzle 31 and
funnel 45 which receives virgin weighting agent 33, e.g., from tank
34 by line 36, and/or recycled weighting agent 38 from separator
78. Venturi mixer/eductor 27 preferably receives sludge from
anaerobic sludge blanket 18, FIG. 1, and/or from anaerobic sludge
blanket 19, FIG. 2A, by line 32.
[0032] In operation, the velocity of sludge in line 32 is increased
through nozzle 31. Virgin weighting agent 33 and/or recycled
weighting agent 38 is dispensed into funnel 45 and then enters
nozzle 31 by line 39 and travels downstream to line 37 and/or line
37' as shown in FIGS. 1 and 2A. The widening of line 37, 37', FIG.
4, shown at 41 induces intimate mixing and entrainment, as shown at
43. This impregnates the virgin and/or recycled weighting agent
into the biological flocs to form weighted biological flocs. The
weighted biological flocs are then returned to anaerobic treatment
reactor 12 by line 37, and/or line 37', FIGS. 1 and 2A, to form
weighted anaerobic sludge blanket 19, FIG. 2A.
[0033] In one design, separator subsystem 78 discussed above may be
configured as shear mill 112, FIG. 5A, which shears the sludge in
line 76 to separate the weighting agent from the weighted
biological flocs. Shear mill 112 ideally includes rotor 80 and
stator 82. In operation, the excess sludge in line 76 enters shear
mill 112 and flows in the direction of arrows 180 and enters rotor
80 and then stator 82. Shear mill 112 is designed such that there
is a close tolerance between rotor 80, FIG. 5B and stator 82, as
shown at 93. Rotor 80 is preferably driven at high rotational
speeds, e.g., greater than about 1,000 r.p.m. to form a mixture of
weighting agent and obliterated flocs in area 181, FIG. 5A, of
shear mill 112. The mixture of weighting agent and obliterated
flocs exits shear mill 112 by line 79, as shown by arrows 184. FIG.
5C shows in further detail the structure of one embodiment of shear
mill 112. Preferably, rotor 80, FIGS. 5A-5C, and/or stator 82
includes slots which function as a centrifugal pump to draw the
excess sludge from above and below rotor 80 and stator 82, as shown
by paths 182, FIG. 5A, and then hurl the materials off the slot
tips at a very high speed to break the weighted biological flocs
into the mixture of weighting agent and obliterated flocs. For
example, rotor 80, FIG. 5B, may include slots 186, and stator 82
may include slots 188. Slots 186 in rotor 80 and/or slots 188 in
stator 82 are preferably optimized to increase shear energy to
efficiently separate the weighting agent from the weighted
biological flocs. The shear developed by rotor 80 and stator 82
depends on the width of slots 186 and 188, the tolerance between
rotor 80 and stator 82, and the rotor tip speed. The result is
shear mill 112 provides a shearing effect which effectively and
efficiently separates the weighting agent from the weighted
biological flocs to facilitate recovery of the weighting agent.
[0034] In another design, separator subsystem 78, FIG. 6, where
like parts have been given like numbers, may be configured as
ultrasonic separator 116. Ultrasonic separator 116 typically
includes one or more ultrasonic transducers, e.g., ultrasonic
transducer 262, 264, 266, 268, and/or 270, available from Hielscher
Ultrasonics GmbH, Stuttgart, Germany, which generates fluctuations
of pressure and cavitation in the excess sludge in line 76. This
results in microturbulences that produce a shearing effect to
create a mixture of weighting agent and obliterated flocs to
effectively separate the weighting agent from the weighted
biological flocs in the excess sludge. The resulting mixture of
weighting agent and obliterated flocs exits ultrasonic separator
116 by line 79.
[0035] In yet another design, separator subsystem 78, FIG. 7, where
like parts have been given like numbers, may be configured as
centrifugal separator 118. Centrifugal separator 114 typically
includes cylindrical section 302 located at the top of hydrocyclone
300 and conical base 304 located below section 302. The excess
sludge in line 76 is fed tangentially into cylindrical section 302
via port 303. Smaller exit port 306 (underflow or reject port) is
located at the bottom of conical section 304 and larger exit port
308 (overflow or accept port) is located at the top of cylindrical
section 302.
[0036] In operation, the centrifugal force created by the
tangential feed of the sludge by port 303 causes the denser
weighting agent to be separated from the biological flocs in the
excess sludge. The separated weighting agent is expelled against
wall 308 of conical section 304 and exits at port 306. This
effectively separates the weighting agent from the weighted
biological flocs. The recovered weighting agent 38 exits via port
306 and may be deposited to weighting agent impregnation system 26,
26', FIGS. 1 and 4. The less dense biological flocs remain in the
sludge and exit via port 308 through tube 310 extending slightly
into the body of the center of centrifugal separator 118.
[0037] Although as discussed above, separator subsystem 78 may be
configured as a shear mill, an ultrasonic separator, or a
centrifugal separator, this is not a necessary limitation of this
invention. In other designs, separator subsystem 78 may be
configured as a tubular bowl, a chamber bowl, an imperforate
basket, a disk stack separator, and the like, as known by those
skilled in the art.
[0038] In the example above where a separator 78, FIGS. 5A-5C, is
configured as shear mill 112 to create the mixture of weighting
agent and obliterated biological flocs, a wet drum magnetic
separator or centrifugal separator 118, FIG. 7, may be used to
recover the weighting agent therefrom.
[0039] In the example where separator subsystem 78, FIG. 6, is
configured as an ultrasonic separator 116 to create the mixture of
weighting agent and obliterated biological flocs, a wet drum
magnetic separator or centrifugal separator 118, FIG. 7, may be
used to recover the weighting agent therefrom.
[0040] The result of recovering and recycling the weighting agent
as discussed above with reference to FIGS. 5A-7 significantly
reduces the operating costs of wastewater treatment system 10.
[0041] Although specific features of the invention are shown in
some drawings and not in others, this is for convenience only as
each feature may be combined with any or all of the other features
in accordance with the invention. The words "including",
"comprising", "having", and "with" as used herein are to be
interpreted broadly and comprehensively and are not limited to any
physical interconnection. Moreover, any embodiments disclosed in
the subject application are not to be taken as the only possible
embodiments. Other embodiments will occur to those skilled in the
art and are within the following claims.
[0042] In addition, any amendment presented during the prosecution
of the patent application for this patent is not a disclaimer of
any claim element presented in the application as filed: those
skilled in the art cannot reasonably be expected to draft a claim
that would literally encompass all possible equivalents, many
equivalents will be unforeseeable at the time of the amendment and
are beyond a fair interpretation of what is to be surrendered (if
anything), the rationale underlying the amendment may bear no more
than a tangential relation to many equivalents, and/or there are
many other reasons the applicant cannot be expected to describe
certain insubstantial substitutes for any claim element
amended.
* * * * *