U.S. patent application number 10/032397 was filed with the patent office on 2002-05-16 for method for separating algae and other contaminants from a water stream.
Invention is credited to Moorehead, Jack.
Application Number | 20020056673 10/032397 |
Document ID | / |
Family ID | 24089791 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020056673 |
Kind Code |
A1 |
Moorehead, Jack |
May 16, 2002 |
Method for separating algae and other contaminants from a water
stream
Abstract
A method and apparatus for treating raw influent water to remove
particles, algae and toxic chemicals from the water. Basically, air
is dissolved in recirculated water under high pressure in an air
contactor unit, the air saturated water is intimately mixed with
the raw, particle bearing, water in a particle mixing system, and
the water, particle and air mixture is passed through an air bubble
separator wherein bubbles formed when the pressure on air saturated
water is reduced carry away toxic gases and particulate material.
If desired for further cleaning the water can be sent through a
second series of air contactor, particle mixer and air bubble
separation, but with a gas comprising ozone to further remove
suspended particles and non-volatile dissolved organic matter. In
order to improve mixing of the particles and the air saturated
water passing through tubes, preferably a pattern of dimples is
formed on at least part of the interior wall of the tubes. Upon
completion of the process the water is ready for use or for further
filtration in a conventional filtration plant.
Inventors: |
Moorehead, Jack; (San Diego,
CA) |
Correspondence
Address: |
FRANK G MORKUNAS
7750 DAGGET ST
SUITE 203
SAN DIEGO
CA
92111
|
Family ID: |
24089791 |
Appl. No.: |
10/032397 |
Filed: |
October 17, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10032397 |
Oct 17, 2001 |
|
|
|
09524578 |
Mar 13, 2000 |
|
|
|
Current U.S.
Class: |
210/104 |
Current CPC
Class: |
C02F 1/20 20130101; C02F
1/283 20130101; C02F 1/24 20130101; C02F 1/38 20130101; C02F 1/78
20130101 |
Class at
Publication: |
210/104 |
International
Class: |
B01D 021/24 |
Claims
I claim:
1. Water decontamination apparatus which comprises: an air
contactor means for introducing air into recirculated water at a
pressure of at least about 70 psi to substantially saturate water
therein; a particle mixer for receiving and mixing said saturated
water from said gas contactor means with influent water containing
at least some contaminants to be removed; means for directing said
water from said air contactor means to said particle mixer at a
pressure less than said gas contactor pressure so that a plurality
of very small bubbles form in said particle mixer; an air bubble
separator having a water inlet adjacent to its bottom for receiving
water from said particle mixer; said air bubble separator
comprising means for causing vortex rotation of received water for
coalescing said bubbles and entrained particles along an axis and
causing decontaminated water to move along an outer wall of said
air bubble separator; first outlet means for removing said
coalesced bubbles and any entrained particles; second outlet means
from said air bubble separator for removing said decontaminated
water; means for removing gases from said bubble separator; and
means for directing a portion of said decontaminated water from
said second outlet to said air gas contactor means as said
recirculated water.
2. The apparatus according to claim 1 wherein said gas contactor
means includes a plurality of hollow porous tubes and includes
means for directing said air into said tubes and said recirculated
water into spaces between said tubes so that said air moves through
said porous tubes and is adsorbed by said recirculated water.
3. The apparatus according to claim 1 further including a pressure
regulator for maintaining pressure at a predetermined level in said
gas contactor means prior to passage of said saturated water to
said particle mixer.
4. The apparatus according to claim 3 wherein said pressure is
maintained at about 100 psi.
5. The apparatus according to claim 1 wherein said particle mixer
comprises an elongated helical tube coil, the internal surface of
said tube coil having a predetermined pattern of dimples over at
least a portion of said surface.
6. The apparatus according to claim 1 wherein said air bubble
separator comprises a vertically oriented tube having a central
axis, an outer wall and upper and central sections above said lower
section with a water outlet in said upper section.
7. The apparatus according to claim 6 wherein said water inlet is
oriented at a predetermined angle so that a rotating water vortex
is formed and said lower section comprises a sump below said water
inlet for collecting heavy particles and a drain for periodically
removing said heavy particles.
8. The apparatus according to claim 6 wherein said central section
has a diameter less than that of the upper and lower sections and
includes gradual transitions therebetween.
9. The apparatus according to claim 6 wherein said upper section
includes a weir over which water rotating in said vortex along said
outer wall flows into a circumferential product trough and a water
outlet means for removing water from said product trough.
10. The apparatus according to claim 6 wherein said upper section
further includes a waste trough for receiving floating waste and a
waste outlet means for removing said floating waste.
11. The apparatus according to claim 6 wherein said upper section
includes a gas relief means for removing gases from said upper
section and level controller means for maintaining a predetermined
water level in said upper section.
12. The apparatus according to claim 6 wherein said particle
separator is a unitary rotationally molded structure comprising a
tubular column having a central region narrower than end regions,
an approximately cylindrical upper section having an outlet for
decontaminated water, an approximately cylindrical top section
having an outlet for coalesced air bubbles and entrained
contaminants.
13. The apparatus according to claim 12 further including a gas
relief valve in said top section for releasing gases.
14. The apparatus according to claim 13 further including level
sensor means for sensing the level of water in said top section and
for opening said valve when water level reaches a predetermined low
level and for closing said valve when water level reaches a
predetermined high level.
15. The apparatus according to claim 1 further including air
compressor means for supplying air at a predetermined pressure to
said gas contactor means.
16. The apparatus according to claim 1 wherein said means for
directing water from said particle mixer to said air bubble
separator comprises pipes having an internal surface with dimples
over at least a portion thereof.
17. Water decontamination apparatus which comprises: a first gas
contactor means for introducing air into recirculated water at a
pressure of at least about 70 psi to substantially saturate water
therein; a first particle mixer for forming a mixture of saturated
water from said first gas contactor means with influent water
containing at least some particles to be removed; means for
directing said saturated water from said first gas contactor means
to said first particle mixer; means for directing said influent
water to said first particle mixer at a pressure less than said
first gas contactor pressure so that a plurality of very small
bubbles form in said particle mixer; a first air bubble separator
having a water inlet adjacent to its lower section for receiving
said mixed water from said first particle mixer; said first air
bubble separator comprising means for causing vortex rotation
around an axis of received water for coalescing said bubbles along
said axis; means for removing said coalesced bubbles and any
entrained material from said first air bubble separator; first
water outlet means from said first air bubble separator; means for
removing gases from said bubble separator; and a second gas
contactor means for receiving water from said first water outlet
means; means for introducing a gas comprising oxygen and ozone into
a second gas contactor means to produce a plurality of very small
dissolved bubbles; a second particle mixer for receiving water from
said second gas contactor means; a second bubble separator
comprising means for coalescing said bubbles along an axis; second
means for removing said coalesced bubbles and any entrained
material; second outlet means for removing treated water from said
second bubble separator; and means for directing a predetermined
portion of said treated water back to said first particle mixer as
said recirculated water.
18. The apparatus according to claim 17 wherein said gas contactor
means includes a plurality of hollow porous tubes and includes
means for directing said air into said tubes and said recirculated
water into spaces between said tubes so that said air moves through
said porous tubes and is adsorbed by said recirculated water.
19. The apparatus according to claim 17 further including a
pressure regulator for maintaining pressure at a predetermined
level in said means for directing water from each of said first and
second gas contactor means to said first and second particle
mixers, respectively.
20. The apparatus according to claim 19 wherein said pressure is
maintained at about 100 psi.
21. The apparatus according to claim 17 wherein each of said first
and second particle mixers comprises an elongated helical tube
coil, the internal surface of said tube coil having a predetermined
pattern of dimples over at least a portion of said internal
surface.
22. The apparatus according to claim 17 wherein said first and
second bubble separators each comprises a vertically oriented tube
having a central axis, an outer wall and upper and central sections
above said lower section with a water outlet in said upper
section.
23. The apparatus according to claim 17 wherein each said water
inlet is oriented at a predetermined angle so that a rotating water
vortex is formed and said each said lower section comprises a sump
below said water inlet for collecting heavy particles and a drain
for periodically removing said heavy particles.
24. The apparatus according to claim 17 wherein each said first and
second central sections has a diameter less than that of the upper
and lower sections and includes gradual transitions
therebetween.
25. The apparatus according to claim 17 wherein each said first and
second upper sections includes a weir over which water rotating in
said vortex along said outer wall flows into a circumferential
product trough and a water outlet means for removing water from
said product trough.
26. The apparatus according to claim 17 wherein each said first and
second upper section further includes a waste trough for receiving
floating waste and a waste outlet means for removing said floating
waste.
27. The apparatus according to claim 17 wherein each said first and
second upper sections includes a gas relief means for removing
gases from said respective upper sections and level controller
means for maintaining a predetermined water level in said
respective upper sections.
28. The apparatus according to claim 17 further including air
compressor means for providing high pressure air to said first and
second gas contactor means and including oxygen concentrating means
and ozone generator means between said air compressor and said
second gas contactor means.
29. The apparatus according to claim 17 wherein said means for
directing water from each said first and second particle mixers to
each said first and second gas bubble separators comprises pipes
having an internal surface with dimples over at least a portion
thereof.
30. The apparatus according to claim 17 wherein said particle
separator is a unitary rotationally molded structure comprising a
tubular column having a central region narrower than end regions,
an approximately cylindrical upper section having an outlet for
decontaminated water, an approximately cylindrical top section
having an outlet for coalesced air bubbles and entrained
contaminants.
31. The apparatus according to claim 30 further including a gas
relief valve in said top section for releasing gases.
32. The apparatus according to claim 30 further including level
sensor means for sensing the level of water in said top section and
for opening said valve when water level reaches a predetermined low
level and for closing said valve when water level reaches a
predetermined high level.
33. A method of removing contaminants from water which comprises
the steps of: directing recirculated first product water into an
air contacting means; directing air at a pressure of at least about
70 psi into said air contacting means to at least partially
saturate said recirculated water; directing said at least partially
saturated water to a particle mixer; directing influent water
containing at least some organic particles to said particle mixer;
mixing said at least partially saturated water and said influent
water while reducing pressure to allow a plurality of very small
air bubbles to form in the resulting mixture and to entrain
particles; directing said mixture to an air bubble separator;
causing said mixture to rotate about an axis in said air bubble
separator so that said bubbles coalesce along said axis with first
product water spaced from said axis; removing said coalesced
bubbles and entrained solid material; and removing said first
product water and recirculating a portion of said first product
water.
34. The method according to claim 33 wherein said mixing is
increased by causing turbulent flow over dimples in walls of said
particle mixer.
35. The method according to claim 33 further including regulating
pressure of water passing from said air contacting means to said
particle mixer to a predetermined level at least about 70 psi.
36. The method according to claim 35 wherein said pressure is
regulated to approximately 100 psi.
37. The method according to claim 33 further including collecting
heavy particles at a lower end of said air bubble separator.
38. The method according to claim 33 further including removing air
bubbles and buoyant particles from a predetermined location at
about an upper end of said air bubble separator.
39. The method according to claim 38 further including removing air
and any gases present from an upper end of said air bubble
separator above said predetermined location.
40. The method according to claim 39 further including maintaining
an interface between said bubbles and buoyant particles and said
air and gases at a predetermined level.
41. A method of removing contaminants from water which comprises
the steps of: directing recirculated second product water into a
first air contacting means; directing air at a pressure of at least
about 70 psi into said first air contacting means to at least
partially saturate said recirculated water; directing said at least
partially saturated water to a first particle mixer; directing
influent water containing at least some organic particles to said
first particle mixer; mixing said at least partially saturated
water and said influent water while reducing pressure to allow a
plurality of very small air bubbles to form in the resulting first
mixture and to entrain particles; directing said first mixture to a
first air bubble separator; causing said first mixture to rotate
about an axis in said air bubble separator so that said bubbles
coalesce along said axis with first product water spaced from said
axis; removing said coalesced bubbles and entrained solid material;
directing said first product water to a second air contacting
means; directing air at a pressure of at least about 30 psi into an
oxygen concentrator to increase the proportion of oxygen therein;
directing gas from said oxygen concentrator to an ozone generator
to increase the proportion of ozone therein to a predetermined
extent; directing gas from said ozone generator into a second air
contacting means to at least partially saturate said first product
water; directing said at least partially saturated first product
water to a second particle mixer; mixing said at least partially
saturated first product water while reducing pressure to allow a
plurality of very small air bubbles to form in the resulting second
mixture and to entrain particles; directing said second mixture to
a second air bubble separator; causing said mixture to rotate about
an axis in said second air bubble separator so that said bubbles
coalesce along said axis with a second product water spaced from
said axis; removing said coalesced bubbles and entrained solid
material; and removing said second product water.
42. The method according to claim 41 wherein said mixing in each of
said first and second particle mixers is increased by causing
turbulent flow over dimples in walls of said particle mixers.
43. The method according to claim 41 further including regulating
pressure of water passing from each of said first and second air
contacting means to said first and second particle mixers,
respectively, to a predetermined level at least about 70 psi.
44. The method according to claim 43 wherein said pressure is
regulated to approximately 100 psi.
45. The method according to claim 41 further including collecting
heavy particles at a lower end of each of said first and second air
bubble separators.
46. The method according to claim 41 further including removing air
bubbles and buoyant particles from a predetermined location at
about an upper end of each of said first and second air bubble
separators.
47. The method according to claim 42 further including removing air
and any gases present from an upper end of each of said first and
second air bubble separator above said predetermined location.
48. The method according to claim 47 further including maintaining
an interface between said bubbles and buoyant particles and said
air and gases at a predetermined level.
49. A particle mixer for use in a water decontamination system,
which comprises; an elongated helical tube; first inlet means for
admitting a first water selected from the group consisting of at
least partially decontaminated, at least partially air saturated,
water at a pressure of at least about 70 and at least partially
decontaminated, partially ozone saturated, into an inlet end of
said elongated helical tube; second inlet means for introducing a
second, raw, water at lower pressure than that of said liquid into
said tube to mix said first and second water; whereby a plurality
of very small gas bubbles spontaneously form in the resulting mixed
water; an outlet pipe for removing said resulting mixture of mixed
water and small gas bubbles; at least a portion of the interior
surface of said tube bears a plurality of spaced dimples turbulence
inducing.
50. The particle mixer according to claim 49 further including a
plurality of said dimples in the interior surface of said outlet
pipe.
51. An air bubble separator for use in a water decontamination
system, which comprises: an elongated, tubular, housing having an
inner wall and a central axis; water inlet means adjacent a first
end of said housing for directing a mixture of water, bubbles and
contaminants into said housing; means for causing vortex rotation
of received water for coalescing said bubbles along said axis and
causing decontaminated water to flow along said inner wall; means
for removing said coalesced bubbles and any buoyant entrained
material from said housing; means for removing decontaminated water
from said housing; means for removing gases from said housing.
52. The air bubble separator according to claim 51 wherein said
housing comprises an inlet section, a central section and an outlet
sections with a contaminated water inlet in said inlet section for
receiving water from said particle mixer and a decontaminated water
outlet in said outlet section.
53. The air bubble separator according to claim 52 wherein said
water inlet means for directing said water from said particle mixer
is oriented at a predetermined angle to said axis so that a
rotating water vortex is formed.
54. The air bubble separator according to claim 52 further
including a sump adjacent to said water inlet, opposite said
central section, for collecting heavy particles and a drain for
periodically removing said heavy particles.
55. The air bubble separator according to claim 52 wherein said
central section has a diameter less than that of the outlet and
inlet sections and includes gradual transitions therebetween.
56. The air bubble separator according to claim 52 wherein said
outlet section includes a weir over which water rotating in said
vortex along said outer wall flows into a circumferential product
trough between said outer wall and weir which communicates with
said water outlet for removing water from said product trough.
57. The air bubble separator according to claim 52 wherein said
outlet section further includes a waste trough for receiving a
mixture of bubbles and buoyant waste and a waste outlet means for
removing said floating waste.
58. The air bubble separator according to claim 52 wherein said
outlet section includes a gas relief means for removing gases from
said outlet section and level controller means for maintaining a
predetermined water level in said outlet section.
59. The air bubble separator according to claim 52 wherein said
column is a unitary plastic structure formed by rotational
molding.
60. The air bubble separator according to claim 59 wherein said
housing comprises an inlet section, a central section and an outlet
sections with a contaminated water inlet in said inlet section for
receiving water from said particle mixer, a approximately
cylindrical first portion of said outlet section having a
decontaminated water outlet and an approximately cylindrical second
portion of said outlet section having an outlet for coalesced
bubbles and any entrained particles therewith.
61. The air bubble separator according to claim 59 wherein said
second portion has a diameter from about 10 to 25 percent greater
than the diameter of said first portion.
Description
FIELD OF THE INVENTION
[0001] This invention relates in general to systems for removing
contaminants from liquids and, more specifically to a system for
removing volatile gases, pesticides and particles such as algae,
other suspended organic solids, dissolved oils and other particles
including large and heavy particles and light, fine or buoyant
particles from water.
BACKGROUND OF THE INVENTION
[0002] Water supplies for domestic drinking water, process water
for chemical plants or other liquids are often contaminated with a
variety of contaminants, such as toxic chemicals, algae, dissolved
oil and various organic and inorganic particles of various sizes.
These contaminants must be removed in a reliable, cost effective
manner.
[0003] Many older water treatment plants use gravitational
separation methods, typically in sedimentation systems or
dual-media sand filtration systems that may not be acceptable under
the newer water quality standards. In some cases, these systems can
meet the standards through the use of properly mixed polymer
chemical filter aids. The required expensive and complex polymer
chemical mixing equipment requires constant attention, since the
amount of the chemicals being added to raw water must be frequently
readjusted to match the continually changing chemistry of the water
being filtered. Slow sand filters require a considerable
investment, but generally can be operate for longer periods without
cleaning. Unfortunately, even with pretreatment, both dual-media
and slow sand filters fail to meet water quality standards for
hours or several days after each backwash cleaning.
[0004] Ordinary chemical flocculation and sedimentation processes
do not prevent toxic chemicals, pesticides and algae from passing
through the ordinary filter bed. If algae spores are present when
chlorine is added, toxic disinfection byproducts are formed, which
is highly undesirable and a violation of the USEPA Safe Drinking
Water Act. The inability of older municipal filtrations systems to
remove algae is apparent in the lack of clarity found when a
swimming pool is filled with "clean" tap water. Most pool
contractors have to shock tap water with large doses of chlorine
chemical pool oxidizer to achieve the desired clear pool water
appearance.
[0005] Particulate material has also been removed from liquids by
floatation, another gravitational method, in which bubbles of a
gas, such as air or oxygen, are introduced into the lower levels of
the liquid and float to the top, carrying fine particles with them.
Various chemical additives, such as flocculation aids, typically
alum polymers, are required with these systems. Flotation is a
gravitational method because the rise of bubbles is due to the
gravitational acceleration acting on the mass of the liquid in
accordance with the basic force equals mass time acceleration
relationship. A force balance relative to a pocket of gas phase
within liquid (a bubble), where the mass of the bubble is its
volume times its density, shows that the bubble must rise to find
equilibrium, because the density of a gas is generally less than
that of a liquid. Large flotation tanks are required to allow
adequate time for air bubbles to reach the surface.
[0006] Failure to remove algae prior to filtration also leads to
clogged filters, increases filter operation costs and wastes water
required for frequent filter cleaning cycles. The use of
flocculation promoting chemicals increases the volume of sludge to
be dewatered and removed.
[0007] Thus, there is a continuing need for a separation system
that will rapidly and efficiently remove particles and volatile
gases from liquids while treating a liquid, will efficiently remove
algae and volatile gases such as MTBE during pretreatment prior to
filtration and will reduce overall treatment costs and conserves
water through less frequent filter cleaning and a smaller sludge
volume.
SUMMARY OF THE INVENTION
[0008] The above noted problems, and others, are overcome in
accordance with this invention by a particle separation system that
includes a pretreatment section for economically removing algae and
other contaminates prior to filtration. The pretreatment includes
injecting millions of extremely small air bubbles per liter into
the incoming raw water. This dissolved air flotation technology
increases a plants daily capacity and reduces the potential
formation of toxic chlorine-chemical and post-treatment
byproducts.
[0009] Initially, recirculated plant output water under high
pressure and air under high pressure are mixed in a an air
contactor element, generally consisting of one tank or two or more
tanks in series. Preferably, the tank contains a suitable media
that provide a high surface areas that increases adsorption of air
into the water. All pressures referred to hereinafter are gauge
pressures.
[0010] The air saturated recirculated water enters a particle
mixing system where it is mixed with raw influent water. The mixed
water passes along a tubular spiral to cause intimate mixing.
Preferably, a pattern of dimples is provided on at least part of
the inner wall of the spiral tube, to increase flow turbulence and
assure optimum mixing.
[0011] The mixed water then passes to an air bubble separator unit
where a toroidal flow is induced as the water moves upwardly in the
unit, producing a vortex that cause air to move to the center and
form an elongated axial air column with the water rotating between
the vessel wall and the air column. Heavy solid particles drop to
the bottom of the unit. Water largely cleaned of algae and other
light particles exits near the top of the unit, with light float
particles being removed adjacent to the top of the unit. Air and
volatile gases exit at the very top of the unit.
[0012] The cleaned water from this air bubble separation unit may
be used for many purposes. However, in some cases further removal
of the small amount of remaining contaminates is desirable. In that
case cleaned water from the air bubble separator then passes to a
second air contactor element at a lower, but above atmospheric,
pressure. Oxygen, preferably containing a suitable quantity of
ozone, is then absorbed or forced into the air contactor tank under
pressure higher than the water pressure. The water now containing a
suitable quantity of dissolved oxygen/ozone passes to a second
particle mixing system similar to the first particle mixing system
as described above. As the process water enters the second particle
mixing system, hydroxyl radicals (dissolved ozone) are mixed with
the remaining suspended particles and non-volatile dissolved
organic matter.
[0013] Water from the second particle mixing system then passes to
a second air bubble separator, similar to the first one as
described above. Bubbles with microscopic suspended particles
coalesce along the unit centerline due to the vortex effect and are
extracted at the top of the unit. The process water, now further
cleaned of algae and other organic particles, may proceed to any
desired conventional filtration system, where any remaining heavy
solid particles are removed. Since the pretreatment system removes
over 85% of the suspended solids in the original untreated water,
filter cycles will be much longer than before, with much lower
operating and filter maintenance costs.
BRIEF DESCRIPTION OF THE DRAWING
[0014] Details of the invention, and of preferred embodiments
thereof, will be further understood upon reference to the drawing,
wherein:
[0015] FIG. 1 is a schematic flow diagram, partially in section, of
a first embodiment of the pretreatment particle separation
system;
[0016] FIG. 2 is a perspective view of the particle mixing
system;
[0017] FIG. 3 is a perspective view of the air bubble
separator;
[0018] FIG. 4 is an axial section view of the upper portion of the
air bubble separator of FIG. 4;
[0019] FIG. 5 is an axial section view of the lower portion of the
air bubble separator of FIG. 4;
[0020] FIG. 6 is a schematic flow diagram, partially in section, of
a second embodiment of the pretreatment particle separation
system;
[0021] FIG. 7 is a detail elevation view, partially cut away, of an
alternate preferred air contractor flow arrangement;
[0022] FIG. 8 is a detail cross sectional view through a
rotationally formed particle mixing system tube in a forming
mold;
[0023] FIG. 9 is a perspective view of an alternative embodiment of
an air bubble separator; and
[0024] FIG. 10 is a side elevation view of the air bubble separator
of FIG. 9.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] A schematic flow diagram for the water treatment system of
this invention is provided in FIG. 1. Raw influent water is
directed into the particle mixing system 10 (described in detail
below) via an inlet pipe 12 as indicated by arrow 14 at any
suitable pressure, typically 30 psi. Simultaneously a suitable
portion of the product water of the system, passing through system
outlet pipe 16, is recirculated through pipe 18 as indicated by
arrows 20 to a pump and flowmeter 22 where pressure is
substantially increased, typically to about 100 psi.
[0026] The high pressure recirculated water passes through pipe 23
to an air contactor arrangement 24 typically including two tanks in
series. High pressure air (typically at about 100 psi) is passed
from a conventional air compressor 26 through a pipe 28. Air is
introduced into the upstream ends of the tanks forming air
contactor 24. The air is dissolved in the high pressure water in
air contactor 24. Any suitable media may be used in the air
contactor tanks to aid in fully saturating the air. For optimum
operation, hollow membrane fibers of the sort available from the
Dainippon Ink and Chemical Corporation under the Separeo EF 04P
designation are preferred. While air contactor 24 preferably
comprises two tanks in series, a single tank or more than two tanks
may be used, if desired.
[0027] Air saturated water passes out of air contactor 24 through a
pressure regulator 30 which reduces pressure to a suitable degree.
A pressure of 25 to 35 psi is preferred, with about 30 psi being
optimum. The air saturated water from air contactor 24 is mixed
with the raw water in particle mixing system 10.
[0028] Particle mixing system 10 as seen in FIG. 2 basically
comprises a helical tube 32 within which the raw water and air
saturated water mixes. The diameter of tube 32, the diameter of the
helix and the length of tube 32 will depend on the volume of water
to be treated. In a typical system, tube 32 will have a diameter of
from about 4 to 10 inches, a length of about 70 to 100 feet, with
the helical coil having a diameter of from about 2 to 6 feet.
[0029] In order to achieve optimum turbulence to ideally mix the
raw water and the air saturated water, I have found that a pattern
of dimples 97 (as shown in FIG. 8) should be provided over at least
a large portion of the inner wall surface of tube 32. Also, output
pipe 36 from the particle mixing system should have these dimples
97 on the interior wall surface.
[0030] The particle mixing system may be manufactured in any
suitable manner. Preferably, the helical tube arrangement will be
formed by conventional rotational casting, using an outer mold half
101 outside the helix and an inner helical mold portion 99 within
the helix having raised bumps 97A to create the dimples 97 on the
tube, as shown in detail in FIG. 8. Regardless on the manner, the
tube 32 may be thus supplied with dimples over almost the entire
inner surface. Base 34 that supports helical tube 32 may be formed
in any suitable manner, such as vacuum forming.
[0031] Returning to FIG. 1, output from helical tube output 36
passes through pipe 38 to inlet 40 of air bubble separator 42.
Millions of very tiny bubbles will form during mixing in particle
mixing system 10 when pressure drops from typically 100 psi in air
contactor 24 to typically 30 psi at pressure regulator 30. These
tiny bubbles adhere to small light weight particles and carry the
particles upwardly in air bubble separator 42.
[0032] Air bubble separator 42 consists of a lower section 44 as
seen in FIGS. 3 and 5, a central section 46 seen in FIGS. 3 and 4
which is generally tubular and may be formed from a transparent
material such as glass or an acrylic resin to permit observation of
flow therethrough and an upper section as seen in FIGS. 3 and
5.
[0033] The mixture of water and air enters tangentially through
inlet 40, setting up a spinning vortex of water flowing upwardly
though center section 46, creating a boundary-layer transfer effect
much like the laminar flow created as water flows through a pipe.
More than one inlet 40 may be used if desired. Inlet 40 may have
any suitable end or nozzle configuration. Each "boundary" layer of
water molecules moves slower because of the frictional drag created
by the slower moving layers closer to the center of the column.
Heavier particles settle in the sump at the lower end of the lower
section 46 and can be drawn off from time to time through a drain
opening 50. Millions of very tiny bubbles form as the saturated
water enters the lower section. The flowing stream of water and
tiny bubbles has the appearance of milk.
[0034] Velocity of the spiraling white-water stream accelerates as
it flows upwardly through the reducing bell-like chamber 52,
creating a high-pressure zone around the outer parameter of the
column and a low-pressure zone in the center of the vortex.
Differential pressure between the outer wall and the vortex center
increases substantially in center section 46. Boundary layer
friction causes the shape of the microscopic bubbles to flatten.
This slower boundary layer frictional drag across the bubble's high
pressure surface side elongates the bubble, which is pulled towards
the center vortex. Flattened microscopic air bubbles passing
through multiple boundary layers collide with relatively stationary
suspended particles in the spiraling stream. Positively charged
polymers and flocculents and microscopic air bubbles attach to the
particles, forcing them to the center. Millions of these
microscopic air bubbles "float" horizontally towards the
low-pressure center of the vortex and tend to coalesce there. This
moving "screen" of microscopic bubbles cleans the water in the
water annulus and outer perimeter areas as the flow spirals
upward.
[0035] Velocity of the spiraling water column is reduced as it
enters the expansion bell chamber 54. Laminar friction holds gases
and the concentrated buoyant float particles near the center of the
vortex until they reach the top of the column.
[0036] Particles and gases stripped from the clean water around the
perimeter of upper section 48 form a concentrated slurry in the
center of the vortex as it enters the float chamber 56. Only small
microscopic bubbles remain near the outer diameter as the water
column flows upwardly. As best seen in FIG. 4, a narrow band of
water near weir lip 58 flows over the edge of the weir lip, exiting
through the product water discharge port 64, typically at a rate of
about 50 to 200 gpm.
[0037] The spinning slurry of buoyant suspended particles and air
bubbles enters the waste float removal chamber 66 and flows over
the edge of waste trough 68, exiting the separator 42 through waste
outlet 70, typically at about 5 to 20 gpm to wasted disposal
through pipe 72 (FIG. 1).
[0038] A conventional level controller 74 activates an air relief
valve 76 at the top of separator 42, regulating the surface level
of the water-air interface inside the top of the water column. Air
relief valve 76 closes as the water level rises and opens when
gasses accumulating at the top of the column causes the surface
water level inside separator 42 to drop. This maintains the surface
level between broken lines 78, correspondingly between the top and
bottom of the waste-float outlet 70.
[0039] Gases exiting through air relief valve 76 pass through pipe
80 to a conventional volatile gas recovery unit 82 (FIG. 1) for
recovery, typically with a carbon filter.
[0040] At this point, the water generally has had nearly all
contaminants removed and can be passed to a conventional water
plant filtration system via output pipe to remove any remaining
large particles. However, in this embodiment a second stage is
added as seen in FIG. 1.
[0041] Where the additional cleaning of the water is desired,
output pipe 84 is connected to a second contactor unit 86,
basically the same as air contactor 24. However here air from air
compressor 26 is passed to a conventional oxygen concentrator 88.
Oxygen concentrator 88 increases the proportion of oxygen in the
gas to about 60 to 90 percent. Next the gas goes to a conventional
corona discharge type ozone generator 90 where a suitable
percentage of the oxygen is converted to ozone. The resulting high
ozone gas is fed to contactor 86 at typically about 35 psi, with
the water in the contactor typically at about 30 psi.
[0042] As the mixture of water and ozone containing gas is directed
to a second particle mixing system 92, basically the same as
particle mixing system 10 described above, where hydroxyl radicals
(dissolved ozone) are mixed with any remaining suspended particles
and non-volatile dissolved organic matter.
[0043] The output of second particle mixing system 92 passes
through pipe 93 to a second air bubble separator 94 generally the
same as air bubble separator 42, as described above. Preferably, a
pattern of dimples is provided over the internal surface of pipe 93
to increase turbulence and the resulting improved mixing, as
discussed above. The coalesced partially oxidized suspended buoyant
particles and volatile gases are extracted by the vortex in
separator 94 and pass to gas recovery unit 82 via pipe 96. This
prefiltration process removes over 85% of the suspended solids from
the treatment plant process water flow. Also, substantially all
algae is removed. This is sufficient to meet present US EPA Clean
Water Act regulations for a minimum 85% removal of suspended
solids. Where further removal is desired, the output water from
particle mixing system 92 can be passed through pipe 16 to any
conventional filtration system.
[0044] As mentioned above, I have found that forming a pattern of
dimples on a suitable portion of the interior of tubes 32 in
particle mixing systems 10 and 92 and in pipes 38 and 93 will
significantly improve turbulence therein and greatly improve mixing
of water with the added gases in the two particle mixing systems 10
and 92.
[0045] FIG. 6 illustrates an alternative embodiment using a single
cleaning stage with the saturated air and eliminates the second,
ozone treatment stage shown in FIG. 1.
[0046] As seen in FIG. 2, the air contactor 24, particle mixing
system 10 and air bubble separator 42 are essentially identical to
the first stage of FIG. 1. Air from compressor 26 is directed to
air contactor 24 together with recirculated water from clean water
output line 84 from air bubble separator 42.
[0047] Saturated water from air contactor 24 passes to particle
mixer 10 where bubbles form and pick up buoyant particles. Water
and bubbles from air contactor 24 then passes to air bubble
separator 42. There, heavy particles are drained away through drain
50, waste water with buoyant particles passes out through waste
pipe 72 and gasses are passed out through pipe 80 to gas recovery
unit 82. Clean water passes out through pipe 84 to and further
filtration treatment, storage or use.
[0048] Water is recirculated through pipe 114 to pump 22 and enters
air contactor 24 to continue the process. The clean water from pipe
84 is suitable for many purposes, such as some process water for
manufacturing facilities and the like. For higher purity purposes,
the system shown in FIG. 1 is preferred.
[0049] FIG. 7 illustrates an alternate flow path for air and
recirculated water through the air contactor unit. Each unit 24
comprises a cartridge having a very large number of thin, porous,
tubes 111 connected to a manifold 113 at the top of each unit 24 so
that air enters all of tubes 111. Meanwhile, recirculated water
enters the top of one unit 24, flows between tubes 111, out the
bottom and to the top of the second unit 24 through pipe 29, thence
between tubes the same as tubes 111 and out the bottom of the
second unit 24 via pressure regulator 30 to the particle mixing
system 10. Air or oxygen forced, by means of an air compressor 26
(as shown in FIGS. 1 and 6), through the open pores in tubes 111 is
adsorbed by the recirculating water flow as it passes over the open
pores. Conventional sensors 115 at the bottom of units 24 sense an
accumulation of air at the bottom of the unit and open a valve in
the sensor to bleed off the air.
[0050] FIGS. 9 and 10 illustrate an alternative embodiment of an
air bubble separator system. Here air bubble separator includes a
single piece, unitary housing 120 preferable formed by conventional
rotational molding. A base 122 may be formed at the same time
housing 120 is formed or may be formed separately and secured to
the housing, such as by adhesive bonding. Water from the particle
mixing system is injected into the air bubble separator through a
tangential inlet 126. An upper portion 124 of housing 122 has a
cylindrical configuration with an outlet 128 through which clean
water is released. At the top is a wider top portion 130, typically
10 to 50% wider than the adjacent upper portion 124, having an
outlet 132. Two level sensors 134 are provided in top portion 130
to measure the water level.
[0051] Typically, level sensors 134 may be NK ultrasonic level
switches from the Kobold company. A gas vent 136 is provided to
vent toxic gases and the like. As discussed above, one of sensors
134 will open gas vent 134 when the water level is low to release
gas and the other will close the gas vent when water level is
high.
[0052] Unit 120 may be formed from any suitable plastic material,
such as a polyolefin or an acrylic. This embodiment is easily and
rapidly manufactured by rotational molding and is highly resistant
to corrosion or other damage from constituents of the water mixture
being processed.
[0053] Other applications, variations and ramifications of this
invention will occur to those skilled in the art upon reading this
disclosure. Those are intended to be included within the scope of
this invention, as defined in the appended claims.
* * * * *