U.S. patent application number 09/915487 was filed with the patent office on 2001-11-15 for system and method for oxygenation of waste water.
This patent application is currently assigned to MG Industries. Invention is credited to Brahmbhatt, Sudhir R., Forde, J. Michael.
Application Number | 20010040134 09/915487 |
Document ID | / |
Family ID | 23938335 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040134 |
Kind Code |
A1 |
Brahmbhatt, Sudhir R. ; et
al. |
November 15, 2001 |
System and method for oxygenation of waste water
Abstract
Oxygen is mixed with waste water at an early stage in a water
treatment facility, to reduce odor caused by anaerobic reactions of
sulfur. Waste water is withdrawn from a collection basin, by a pump
connected to a suction pipe, and is mixed with oxygen from an
external source. The mixture, having been saturated with oxygen, is
then returned to the collection basin through a discharge pipe. The
end of the discharge pipe is positioned at a higher vertical level
than the end of the suction pipe, to prevent gas from entering the
pump which would cause cavitation. Also, the end of the discharge
pipe has a blind flange, such that the oxygen-enriched water
exiting the discharge pipe flows in a direction which is
non-parallel to the axis of the pipe. This arrangement provides
better mixing of the oxygen with the water in the basin, and
prevents the oxygen-enriched water from flowing too soon to the
suction pipe. The invention substantially improves the efficiency
and efficacy of waste water treatment, because it provides an
economical way to oxygenate the waste water at an early stage in
the treatment process.
Inventors: |
Brahmbhatt, Sudhir R.;
(Glencoe, MO) ; Forde, J. Michael; (Orange Park,
FL) |
Correspondence
Address: |
William H. Eilberg
420 Old York Road
Jenkintown
PA
19046
US
|
Assignee: |
MG Industries
|
Family ID: |
23938335 |
Appl. No.: |
09/915487 |
Filed: |
July 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09915487 |
Jul 25, 2001 |
|
|
|
09488105 |
Jan 20, 2000 |
|
|
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Current U.S.
Class: |
210/758 |
Current CPC
Class: |
Y10S 261/70 20130101;
Y02W 10/10 20150501; B01F 25/53 20220101; C02F 1/74 20130101; C02F
3/26 20130101; C02F 1/72 20130101; B01F 23/29 20220101; C02F 1/76
20130101 |
Class at
Publication: |
210/758 |
International
Class: |
C02F 001/72 |
Claims
What is claimed is:
1. A system for dissolving oxygen in a waste water collection
basin, comprising: a) a source of oxygen, the oxygen source being
connected to a discharge pipe having an end located in the
collection basin, b) a suction pipe having an end located in the
collection basin, and c) a pump connected to the suction pipe and
to a mixing unit which is connected to the oxygen source, wherein
the end of the discharge pipe is positioned above a level of the
end of the suction pipe.
2. The system of claim 1, wherein the discharge pipe has a side
wall, wherein the discharge pipe has a plurality of holes disposed
in the side wall, and wherein the discharge pipe includes a blind
flange connected to the end of the discharge pipe.
3. A system for dissolving oxygen in a waste water collection
basin, comprising: a) a source of oxygen, the oxygen source being
connected to a discharge pipe having an end located in the
collection basin, b) a suction pipe having an end located in the
collection basin, and c) a pump connected to the suction pipe and
to a mixing unit which is connected to the oxygen source, wherein
the discharge pipe has a side wall, wherein the discharge pipe has
a plurality of holes disposed in the side wall, and wherein the
discharge pipe includes a blind flange connected to the end of the
discharge pipe.
4. The system of claim 3, wherein the end of the discharge pipe is
positioned, within the collection basin, above a level of the end
of the suction pipe.
5. The system of claim 4, wherein the end of the discharge pipe is
positioned at least two feet above the level of the end of the
suction pipe.
6. A system for oxygenation of waste water in a collection basin,
comprising: a) means for providing pressurized oxygen, b) means for
withdrawing waste water from the collection basin, c) means for
mixing oxygen from the oxygen providing means with waste water from
the withdrawing means to produce oxygen-enriched water, and d)
means for conveying said oxygen-enriched water to the collection
basin and for discharging said oxygen-enriched water into the
collection basin, wherein the discharging means is positioned at a
vertical level which is different from a vertical level of the
withdrawing means.
7. The system of claim 6, wherein the discharging means includes a
conduit having a longitudinal axis, and wherein the conduit
includes means for directing fluid flow out of the conduit in a
direction which is non-parallel to said longitudinal axis.
8. A system for oxygenation of waste water in a collection basin,
comprising: a) means for providing pressurized oxygen, b) means for
withdrawing waste water from the collection basin, c) means for
mixing oxygen from the oxygen providing means with waste water from
the withdrawing means to produce oxygen-enriched water, and d)
means for conveying said oxygen-enriched water to the collection
basin and for discharging said oxygen-enriched water into the
collection basin, wherein the discharging means includes a conduit
having a longitudinal axis, and wherein the conduit includes means
for directing fluid flow out of the conduit in a direction which is
non-parallel to said longitudinal axis.
9. A method of oxygenating waste water in a collection basin, the
method comprising: a) withdrawing waste water from the collection
basin, b) mixing the waste water withdrawn in step (a) with oxygen
to form oxygen-enriched water, and c) injecting said
oxygen-enriched water into the collection basin, wherein the
injecting step and the withdrawing step are performed
simultaneously at different vertical levels within the collection
basin.
10. The method of claim 9, wherein the injecting step is performed
at a higher vertical level than the withdrawing step.
11. The method of claim 9, wherein the injecting step comprises
delivering the oxygen-enriched water to the collection basin
through a conduit having a longitudinal axis, and directing the
oxygen-enriched water out of the conduit in a direction which is
non-parallel to said longitudinal axis.
12. The method of claim 10, wherein the injecting step comprises
delivering the oxygen-enriched water to the collection basin
through a conduit having a longitudinal axis, and directing the
oxygen-enriched water out of the conduit in a direction which is
non-parallel to said longitudinal axis.
13. A method of oxygenating waste water in a collection basin, the
method comprising: a) withdrawing waste water from the collection
basin, b) mixing the waste water withdrawn in step (a) with oxygen
to form oxygen-enriched water, and c) injecting said
oxygen-enriched water into the collection basin, wherein the
injecting step comprises delivering the oxygen-enriched water to
the collection basin through a conduit having a longitudinal axis,
and directing the oxygen-enriched water out of the conduit in a
direction which is non-parallel to said longitudinal axis.
14. In a waste water treatment system, the system having a
plurality of water treatment stages, the water treatment stages
being preceded by at least one collection stage, the improvement
comprising a source of oxygen connected to said collection stage,
wherein oxygen is mixed with waste water in the collection stage
before being treated in the system.
15. The improvement of claim 14, further comprising a suction pipe
having an end located in the collection stage, and a pump connected
to the suction pipe and to a mixing unit which is connected to the
oxygen source, wherein the end of the discharge pipe is positioned
above a level of the end of the suction pipe.
16. The improvement of claim 14, wherein the source of oxygen
enters the collection stage through a discharge pipe, and wherein
the discharge pipe has a side wall, wherein the discharge pipe has
a plurality of holes disposed in the side wall, and wherein the
discharge pipe includes a blind flange connected to the end of the
discharge pipe.
17. The improvement of claim 15, wherein the source of oxygen
enters the collection stage through a discharge pipe, and wherein
the discharge pipe has a side wall, wherein the discharge pipe has
a plurality of holes disposed in the side wall, and wherein the
discharge pipe includes a blind flange connected to the end of the
discharge pipe.
18. In a method for treating waste water, the method including
treating the water in a plurality of water treatment steps, the
water treatment steps being preceded by at least one waste water
collection step, the improvement comprising mixing oxygen with the
waste water, during the collection step, before treating the waste
water.
19. The improvement of claim 18, wherein the mixing step comprises
withdrawing waste water from a collection basin, mixing the
withdrawn waste water with oxygen to form oxygen-enriched water,
and injecting the oxygen-enriched water into the collection basin,
wherein the withdrawing and injecting steps are performed at
different vertical levels within the collection basin.
20. The improvement of claim 19, wherein the injecting step is
performed by passing the oxygen-enriched water through a discharge
pipe having a longitudinal axis, and directing the oxygen-enriched
water out of the discharge pipe in a direction which is
non-parallel to said longitudinal axis.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to the field of waste water
treatment, and provides a system and method for oxygenating waste
water at an early stage of the waste water treatment process.
[0002] In a typical waste water treatment facility, waste water is
collected from various sources, including residential and/or
industrial sources. The waste water from these sources is initially
held in a collection basin, also known as a diversion box. The
water is then conveyed to one or more settling tanks, wherein
debris in the water is allowed to settle. The water can then be
filtered one or more times, aerated, and treated with chemicals
such as ozone, chlorine, etc. There may be one or more further
collection basins positioned before the first filtration stage.
[0003] Bacteria in the water attack organic material in the water,
consuming oxygen in the process. But since the water reaching the
collection basin is delivered through underground conduits, the
supply of oxygen in the water is limited. If there is insufficient
oxygen available to support the reactions which would naturally
occur in the presence of oxygen, anaerobic reactions take place
instead. Such reactions typically include the chemical combination
of sulfur with hydrogen to produce hydrogen sulfide, a very odorous
gas. Elimination of foul odors, and promoting biological oxidation
reactions, are major concerns in the field of waste water
treatment.
[0004] The known solution to the above-described problem is to
oxygenate the water. When the deficiency of dissolved oxygen is
overcome, the odor problem is greatly reduced or eliminated.
[0005] It has therefore been proposed, in the prior art, to provide
a source of pure oxygen at high pressure, to dissolve this oxygen
in a sample of the waste water, and to return the oxygenated sample
to the basin being treated.
[0006] One prior art arrangement for performing the above steps is
shown in FIG. 1. Oxygen From a supply (not shown) flows into
conduit 1, through valve 3, and into mixing device 5. Waste water
located in collection basin 7 is drawn out by pump 11, through
suction pipe 9, and sent to the mixing device. The mixture of
oxygen and waste water is then introduced into the collection basin
through discharge pipe 13. The discharge pipe is connected to a
plurality of nozzles 15 located at or near the bottom of the
collection basin.
[0007] The major problem with the method described above is that
the nozzles easily become clogged with debris which is almost
always present in the waste water.
[0008] Another proposed solution of the prior art is shown in FIG.
2. In this embodiment, the nozzles have been eliminated. Instead,
the ends of discharge pipe 21 and suction pipe 23 are displaced
from the bottom of the basin. In the example given in the figure,
these ends are positioned about midway between the top and bottom
of the basin. In this embodiment there are two oxygen lines, one of
which is used as a backup in the event that the pump 27 becomes
clogged or in the event that cavitation renders the pump
ineffective. Also in this embodiment, a screen (not shown) is used
at the inlet to suction pipe 23, to prevent debris in the water
from interfering with the operation of pump 27.
[0009] The system described above is still not practical. Its major
problem is that it causes cavitation in the pump. As the screen
becomes clogged, the pump has less and less to pull, resulting in
reduced suction in the line. Changes in pressure in the line may
cause oxygen to come out of solution, and if this occurs, the pump
will tend to pull both gas and water out of the basin. The presence
of gas in the line causes damage to the pump.
[0010] The present invention provides a system and method which
allows the oxygenation of waste water in a collection basin, but
which nevertheless does not suffer from the disadvantages of the
prior art described above.
SUMMARY OF THE INVENTION
[0011] The present invention comprises a system which connects a
source of pressurized oxygen to a mixing device. A pump draws some
of the waste water out of a collection basin, and directs this
water to the mixing device, where the water and oxygen are mixed so
that the oxygen is dissolved in the water. This oxygen-enriched
water produced in the mixing device is conveyed to a discharge
pipe, the end of which sits within the waste water in the basin. A
suction pipe, connected to the pump, withdraws a portion of the
contents of the basin. The ends of the discharge pipe and the
suction pipe are at different vertical levels. In the preferred
embodiment, the end of the discharge pipe is located above the end
of the suction pipe. In operation, water is continuously withdrawn
from the basin, while oxygen-enriched water is continuously
injected into the basin.
[0012] The end of the discharge pipe preferably includes a blind
flange, which tends to prevent returned waste water from flowing
directly out of the discharge pipe. Instead, the oxygen-water
mixture is directed out of the discharge pipe, through holes in its
side wall, in a direction which is non-parallel to the longitudinal
axis of the pipe. This arrangement assures that the mixture will
not directly enter the suction pipe, but will instead become evenly
dispersed through the basin. Thus, the suction pipe does not
"short-circuit" the discharge pipe.
[0013] The invention therefore also includes the method of
oxygenating the contents of a waste water collection basin by
mixing some of the waste water with oxygen, such that the oxygen
becomes dissolved in the water, and introducing the oxygen-enriched
water into the basin at a vertical level different from that at
which water in the basin is removed. The introducing step is
performed by introducing the mixture in a direction which is
generally perpendicular, or at least non-parallel, to the flow of
fluid in the discharge pipe.
[0014] The present invention virtually eliminates the cavitation
problem associated with systems of the prior art, making it
feasible to oxygenate waste water at an early stage of its
processing.
[0015] The present invention therefore has the primary object of
providing a system and method for oxygenation of waste water.
[0016] The invention has the further object of preventing
cavitation in a pump used to draw waste water from a collection
basin, for use in an oxygenation process.
[0017] The invention has the further object of reducing or
eliminating foul odors in a collection basin in a waste water
treatment facility.
[0018] The invention has the further object of oxygenating waste
water at a relatively early stage in a waste water treatment
plant.
[0019] The invention has the further object of improving the
efficiency and effectiveness of waste water treatment.
[0020] The reader skilled in the art will recognize other objects
and advantages of the present invention, from a reading of the
following brief description of the drawings, the detailed
description of the invention, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 provides a schematic diagram of a system of the prior
art, for oxygenating waste water in a collection basin.
[0022] FIG. 2 provides a schematic diagram of another system of the
prior art, for oxygenating waste water.
[0023] FIG. 3 provides a schematic diagram of the system of the
present invention.
[0024] FIG. 4 provides a fragmentary elevational view of the end of
the discharge pipe used in the present invention.
[0025] FIG. 5 provides a block diagram of a typical waste water
treatment facility using the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] FIG. 3 provides a schematic diagram of the system of the
present invention. Oxygen from a supply (not shown) flows into the
system through conduit 31. The oxygen is preferably at a high
pressure, typically 150 psig. The oxygen flows to sparging or
mixing unit 33 through conduit 35, which includes manual blocking
valve 37, pressure regulator 39, flow control valve 41, solenoid
valve 43, and check valve 45. The solenoid valve is intended to
close in the event of an emergency. The contents of the mixing unit
pass through blocking valve 47, and then through discharge pipe 49
which terminates in collection basin 51.
[0027] Suction pipe 53 also has an end terminating in the
collection basin, and is connected to pump 55. The output of the
pump passes through check valve 57, blocking valve 59, and then to
mixing unit 33. The blocking valves allow portions of the system to
be isolated for maintenance.
[0028] The pump is preferably a self-priming pump. In one
embodiment, the pump may have a capacity of about 600 gallons per
minute. Pumps having a capacity greater or less than 600 gpm can be
used, depending on the size of the system. The invention is not
limited to a specific capacity.
[0029] An oxygen bypass line 61 provides an alternate path for
oxygen in the event of cavitation in the pump, or if the pump
becomes inoperative for some other reason.
[0030] The end 63 of the discharge pipe is displaced vertically
relative to the end 65 of the suction pipe. In the preferred
embodiment, the end of the discharge pipe is positioned above the
end of the suction pipe. This vertical displacement is represented
by reference symbol "a" in FIG. 3. In one example, the value of "a"
may be about two feet. The latter dimension is given only as an
example, and is not intended to limit the invention. The optimum
height difference between the two pipes may be affected by other
factors, such as the flow rate of the water, the amount of oxygen
dissolved, and the size of the basin.
[0031] The discharge pipe and the suction pipe should be spaced
sufficiently close that the oxygen remains in the main flow stream,
but sufficiently far apart that the oxygen does not
"short-circuit", i.e. that it does not enter the suction pipe
before having spent any time in the basin. It is important that the
oxygen remain in flowing water; the oxygen will not serve the
desired purpose in stagnant water. The residence time of the oxygen
in the water is short, and if the oxygen is not used immediately,
it will not be effective in supporting the desired chemical
reactions.
[0032] In operation, water from the basin is withdrawn continuously
through the suction pipe, and the oxygen-enriched water from the
mixing unit is continuously conveyed into the basin through the
discharge pipe. Due to the action of the pump, these steps are
performed simultaneously.
[0033] Positioning the ends of the discharge pipe and the suction
pipe at different heights tends to prevent gas from entering the
suction pipe, thus preventing cavitation in the pump. The oxygen
mixed with the water is dissolved in the water before it reaches
the suction pipe, and thus there is no gas to cause cavitation.
Moreover, the use of water containing dissolved oxygen provides the
conditions necessary to reduce or eliminate foul odors in the
water.
[0034] FIG. 4 shows the preferred structure of the end of the
discharge pipe. The discharge pipe includes cylindrical body 67
having holes 69 formed in the side wall of the body. The pipe also
includes blind flange 71 which is offset from the end of the pipe.
That is, an opening is formed between the end of the discharge pipe
and the blind flange. Thus, the blind flange inhibits the flow of
fluid directly out of the end of the discharge pipe. Some of the
fluid in the discharge pipe will flow out through the holes 69, and
some of the fluid will be diverted by the blind flange, and will
flow out through the opening between the end of the discharge pipe
and the blind flange. In either case, fluid exits the discharge
pipe in a direction indicated by arrow 73, which is generally
perpendicular, or at least non-parallel, to the longitudinal axis
of the pipe, which is the direction of flow of fluid in the pipe.
This arrangement tends to prevent gas from entering the suction
pipe before it is further mixed with the waste water.
[0035] The use of the discharge pipe having the structure shown in
FIG. 4 further helps to mix the oxygen more thoroughly with the
waste water, as the waste water and oxygen mixture is directed
laterally through the collection basin, and not directly to the
area of the suction pipe. Also, the fact that the ends of the
discharge pipe and suction pipe are vertically displaced from each
other further reduces the "short-circuiting" effect wherein water
tends to flow out of the discharge pipe and directly into the
suction pipe. Proper treatment of the waste water requires that the
oxygen be mixed uniformly through the basin. The present invention
accomplishes this aim in a practical and efficient manner.
[0036] In the prior art system of FIG. 2, a screen was used on the
inlet to the suction pipe to prevent debris from reaching the pump.
Experience with the arrangement of FIG. 2 has shown that the screen
itself becomes quickly clogged with debris. In the present
invention, there is no such screen. One can select the size of the
pump so as to handle debris of a given size. The risk to the pump
comes from cavitation, but, as explained above, the present
invention reduces or eliminates this risk.
[0037] FIG. 5 provides a block diagram of a typical waste water
treatment facility, as modified according to the present invention.
This diagram shows the stages of the system, and the steps of the
method, for treating the waste water.
[0038] Waste water enters through conduit 100, and flows into
primary diversion box (or basin) 101. Debris settles out of the
water in primary settling tank 102. Sludge from this tank exits
through line 112. There may be a plurality of primary settling
tanks, in which case such tanks would be connected in parallel. The
water then flows into a first stage trickling filter diversion box
103. The water is then filtered in trickling filter 104, which
could also comprise a plurality of filters connected in parallel.
The filtered water passes to trickling filter conversion box 105,
and into tertiary settling tank 106. As before, tank 106 could be
replaced by a plurality of tanks connected in parallel.
[0039] Next, the water flows to tertiary aeration tank 107, and to
final diversion box 108. Sludge from diversion box 108 is recycled,
through line 111, to the primary settling tank 102. In intermediate
diversion box 109, the water is treated with chlorine, and the
treated water flows into intermediate tank 110 (which could
comprise more than one tank connected in parallel) and out of the
system through line 113.
[0040] FIG. 5 also illustrates, schematically, the injection of the
oxygen-enriched water, through line 115, and the withdrawal of
water from the basin, through line 117, as described earlier.
[0041] In the embodiment shown, oxygen is mixed with the water in
diversion box (or collection basin) 101, which comprises the first
major step of the water treatment process. Oxygen could also be
injected at later points in the process.
[0042] The present invention is believed to be the first practical
system for oxygenation of waste water in a collection basin. In the
prior art, it has been known to oxygenate waste water, but only at
later stages in the water treatment process, such as in aeration
basins positioned considerably downstream of the waste water
intake. By effectively oxygenating waste water in a collection
basin, i.e. at or near the point where the waste water first enters
the system, and in any case before the first significant filtration
or treatment step, one greatly improves the efficiency of the water
treatment process.
[0043] The invention can be modified in various ways. The specific
arrangement of blocking valves and pressure regulators can be
varied according to the needs of the user. The specific shape of
the collection basin may vary. The invention is not limited by the
particular structure of the mixing unit or of the pump. These and
other similar modifications will be apparent to the reader skilled
in the art, and should be considered within the spirit and scope of
the following claims.
* * * * *