Note: Descriptions are shown in the official language in which they were submitted.
363
-- 1 --
RETRIEVABLE JET MIXING SYSTEMS
The present invention is directed to methods and
apparatus for wastewater treatment, and more particularly,
to such methods and apparatus s~hich may be utilized in
the aeration of wastewater liquids and which may be
readily retrieved, serviced and replaced in operation.
Methods and apparatus for the aerobic treatment
of wastewater such as industrial waste, sewage and the
like conventionally utilize oxygenation to promote the
rapid aerobic growth of microorganisms and the concom-
mitant oxidation and consumption of particulate and
dissolved effluent waste components. Such aerobic
wastewater treatment systems may conventionally utilize
various types of aeration entrancing apparatus such as a
1~ jet aeration apparatus for introducing oxygen into the
wastewater liquid and for transferring momentum to the
wastewater liquid to maintain mixing and to prevent
sedimentation of particulate wastes and microbiological
agglomerates.
2~ In the operation of jet aeration systems,
typically a motive stream jet of the waste liquid is
mixed in a mixing chamber with an oxygen containing gas
as a secondary fluid and discharged by means of a suit-
able discharge nozzle as a mixed gas-liquid stream into
25 and below the surface of the wastewater to be aerated.
Typically, the jet aeration apparatus including asso-
ciated piping for pressurized air is solidly assembled
and mounted near the bottom of the wastewater treatment
basin.
While jet aeration systems are very effective
for wastewater treatment, solid materials such as stones,
plastic wastes or particulate materials may clog the
mixing chambers, pump, and~or the discharge orifices of
the jet aeration apparatus. Moreover, because of the
~"a
~Z5~3
active biological nature of the treatment system, it may
be necessary or desirable to pe~iodically remove bio-
logical growth which adheres to the surfaces of the
aeration apparatus.
Conventionally, it has been necessary to periodi-
cally drain the aeration tankage to utilize divers and/or
to produce a reverse fluid flow through the system in
order to manually clean and se:rvice the equipment. These
methods have various disadvantages, and are not wholly
1~ adequate or desirable for maintainance of jet aeration
systems.
Accordingly, it is an object of the present
invention to provide improved methods and apparatus for
aerating wastewater basins which may be readily cleaned
15 or otherwise serviced without interruption of the
operation of the wastewater treatment basin.
These and other objects of the invention will
become more apparent from the Eollowing detailed
description and the accompanying drawings of which:
FIGURE 1 is a cross-sectional partially
transparent side view of an embodiment of retrievable
aeration apparatus in accordance with the present
invention;
FIGURE 2 is a partially transparent side view of
25 an embodiment of an aeration nozzle assembly similar to
that of FIGURE l;
FIGURE 3 is a plan view of a retrievable aeration
apparatus in accordance with the present invention
disposed with a sludge holding tank;
FIGURE 4 is a cross-sectional partially trans-
parent side view of the aeration apparatus of FIGURE 4;
FIGU~E 5 is a plan view of a multiple nozzle
retrievable aeration system disposed within a wastewater
treatment tank;
FIGURE 6 is a cross-sectional partially trans-
~Z~ 3
-- 3 --
parent view o~ the retrievable multiple nozzle aeration
apparatus o~ FIGURE 5 taken through line 6-6;
FIGURE 7 is a plan view of another embodiment oE
a multiple nozzle retrievable multiple nozzle aeration
appartus disposed within a wastewater treatment tank; and
FIGURE 8 is a cross-sectional partially trans-
parent side view of the retrievable multiple nozzle
aeration apparatus of FIGURE 7 taken through line 8-8.
Generally in accordance with the present
1~ invention, methods and apparatus are provided for
wastewater treatment by aeration. In accordance with
various apparatus aspects of the present invention,
wastewater aeration apparatus is provided comprising a
wastewater treatment reservoir means for retaining the
15 waste~ater to be aerated, an air delivery means for
providing an oxygen containing gas such as air comprising
an upstanding conduit affixed at a predetermined position
within the reservoir means, a retrievable jet aerator
means comprising a motive fluid pump means for providing
23 at least one primary motive stream of liquid wastewater
from within the reservoir means and a jet mixing nozzle
means for combining said at least one primary motive
stream with a secondary fluid and for discharging the
combined primary motive liquid and secondary Eluid into
~5 the wastewater contained in the reservoir.
The jet mixing nozzle means further comprises a
secondary fluid inlet conduit means for receiving the
upstanding conduit of the air delivery means such that
o~ygen containing gas released by the upstanding conduit
30 is dircted into the secondary fluid inlet conduit.
Further in accordance with various aspects of apparatus
in accordance with the present invention, guide and
support means are provided for guiding the retrievable
~et aerator means into predetermined position within
3; reservoir such that the secondary fluid inlet conduit
~Z~V~i3
-- 4 --
means hydrostatically encloses the discharge orifice of
the upstanding air delivery conduit, for supporting the
retrievable jet aerator means in jet aeration operation
at said predetermined position, and for permitting
withdrawal of the jet aerator means from the reservoir
for servicing.
Also in accordance with various aspects of the
present invention, methods are provided for retrievably
assembling a wastewater aeration system. In accordance
~0 with such methods, an air source having an upstanding
discharge pipe is provided at a predetermined location
within a wastewater treatment basin, and a jet aeration
assembly having a downwardly directed secondary fluid
inlet conduit is retrievably positioned over the dis-
5 charge orifice of the gas discharge pipe, such that ahydrostatic head of at least abou. l inch of water is
provided between the discharge orifice and the highest
elevation of the secondary fluid inlet orifice. The jet
aeration assembly thus positioned may be readily removed,
20 serviced and replaced.
Illustrated in FIGURE 1 is an embodiment lO of
apparatus for treating wastewater which is constructed in
accordance with various aspects of the present invention.
As illustrated in FIGURE l, the wastewater aeration
25 treatment apparatus lO comprises reservoir means 12 for
retaining the body of wastewater 14 to be aerated and a
jet aeration system 20 including a retrievable pump and
motive jet aeration assembly. The reservoir 12 may be
constructed in accordance with conventional practice and
3~ will typically be tankage constructed oE reinforced
concrete. The illustrated jet aeration apparatus 20
comprises air supply means 22 for discharging a pres-
surized stream of air beneath the ~urface of the waste-
water to be treated. In the illustrated embodiment, the
35 air supply means 22 may comprise a suitable blower (not
shown) located e~ternally of the reservoir, an upstanding
air supply pipe 24 oE pretermined length and diameter as
will be described in more detail h~reinafter, and air
supply conduit 26 connecting the blower and the upstanding
air supply conduit. The air supply conduit 26 and pipe
24 may be suitably fabricated from wastewater resistant
materials such as fiberglass reinforced polyester resin.
The illustrated upstanding conduit 24 may have an
external diameter of about 4 inches. The aeration
1~ apparatus 20 Eurther comprises pump means 30 for
providing a pressurized stream of waste liquid for
utilization in the aeration apparatus. In the
illustrated embodiment, the liquid pump means 30 is a
submersible pump assembly comprising a submersible
~5 electric motor 32 and a centrifugal pump 34 integral
therewith and having an intake orifice at the lower end
thereof. Electrical power to the pump may be provided by
a suitable electrical cable which does not interfere with
the travel of the motor along the guide rails, as will be
20 described in more detail. The pressurized discharge from
the pump assembly 30 is forced through an elipitcal
nozzle 40 (shown by dotted lined in transparent view)
into an enclosed mixing chamber 42. Also communicating
with the enclosed mixing chamber 42 is a downwardly
depending sleeve 44 terminating in an outwardly flared
flange 46. As illustrated in FIGURE 1, the sleeve 44 and
flange 46 have a diameter which is greater than the
diameter of the upstanding air supply pipe 24 such that
the sleeve assembly 44, 46 may engage the upstanding air
30 pipe 24 in telescoping relationship such that air
released from the upstanding air delivery pipe 24 is
directed into the mixing chamber 42. In this manner, a
hydrostatic seal is provided having a pressure diE-
ferential generally corresponding to the distance between
35 the bottom opening oE the flange 46 and the discharge
orifice of the upstanding air conduit 24. This height
may typically be between about one inch to about 20
inches, providing a corresponding hydrostatic pressure
head for sealing the air delivery of 1-20 inches of
water, and preferably from about 4 inches to about 10
inches. In the illustrated embodiment 20, the nominal
hydrostatic seal provided is about 7 inches of water.
The jet nozzle assembly illustrated in FIGURE 1 further
comprises a secondary nozzle assembly 50 which includes
10 an inwardly flared converging section 50, a straight
cylindrical throat section 52 connected at the downstream
end of the converging section S0, and an outwardly flared
discharge section 54 which may be connected to the down-
stream end of the straight section 52, and from which the
15 jet mixture is discharged. The illustrated jet mixing
system is a double nozzle assembly which may be used to
combine, mix, or intimately contact two different fluids.
The double nozzle assembly comprises a primary nozzle, a
mixing chamber and a secondary nozzle assembly. The
20 motive fluid, which in the illustrated embodiment is the
waste liquid fluid from the tank, passes through the
primary nozzle 40 creating a high velocity stream as it
enters the mixing chamber, and the combined fluids are
subsequently discharged from the second nozzle assembly
~5 50, 52, 54. In operation, the action of the motive
stream within the mixing chamber 42 may provide a
hydrodynamic pressure seal component in addition to (or
in lieu of) the hydrostatic pressure seal previously
described. In this regard, the pressure within the
30 mixing chamber ~2 will depend in part on the relative
volume and pressure of the air delivered to the mixing
chamber. At relatively low delivery levels, a relative
vacuum may be aerated with resplect to stable pressure
conditions, ~which may cause wastewater 14 to be drawn
35 into the mixing chamber 42 along the zone defined
~2~ S3
therebetween the inner support of the secondary fluid
inlet conduit 44 and the outer surface of the discharge
pipe. Accordingly, this distance should desirably be
less than the discharge orifice dimension to prevent
nozzle clogging, although a deformable plastic webbing or
filter element therebetween ma~y accomplish this purpose.
At higher relative gas to moti~ve stream ratios, a positive
pressure may be provided in the mixing chamber relative
to the static pressure. Typically, the jet aeration
1~ apparatus may be operated with a slight positive pres-
sure, which will not exceed the hydrostatic seal pressure
provided by the vertical overlap of the secondary inlet
conduit 44, 46 with the air pipe 24. The jet discharge
from the nozzle assembly 50, 52, 54 creates secondary
15 mixing patterns throughout the tank.
The illustrated jet nozzle assembly has no
moving parts for ease of maintenance, and its smooth
molded surfaces greatly reduce the potential for clogging
of the nozzle assembly. In this regard, the nozzle
20 assembly may be manufactured oE structurally sound,
corrosion resistant fiberglass reinforced polyester as a
structural unit. Furthermore, as will now be described
in more detail, the illustrated jet nozzle assembly is
retrievable from the tankage. The secondary fluid enters
2; the nozzle assembly through the bottom inlet without the
necessity for a mechanical seal. The hydrostatic and
hydrodynamic head created within the mixing chamber by
the motive fluid forces the blended mixture out of the
discharge nozzle 50, 52, 54 while sealing the suction
30 connection at the secondary inlet assembly 44, ~6.
The illustrated jet aeration assembly apparatus
20 fu~ther includes means 60 for guiding the retrievable
jet aeration assembly in telescoping relationship with
the upstandirlg air discharge pipe 24. The guiding means
35 60 in the illustrated embodiment comprises a pair of
l;~S~
stainless steel guide rails, one o~ which is shown in
FIGURE 1 by reference numeral 62. The guide rails 62 are
securely fastened to the bottom of the tank without
obstructing the pump inlet orifice by appropriate
fastening elements, and terminate above the water level
with connection to a horizontally mounted ~ramework 6~.
The guide rail assembly further includes a permanent
platform 66 for supporting the weight of the motor, pump,
and nozzle assembly at a predetermined distance above the
13 bottom of the tank such that the upstanding air discharge
pipe 24 projects into the downward projecting inlet port
assembly ~4, 46, a predetermin~ed distance to provide a
fluid seal, and without projecting into the mixing
chamber so as to obstruct the flow of fluid within the
15 chamber.
The pump assembly is further provided with guide
elements 68 which interact in sliding relationship with
the guide rail 62 and which permit the jet aeration
assembly 20 to be raised and lowered along the rail 62
20 ~hile restricting horizontal and rotational motion by the
retrievable jet assembly. In this regard, the guide
elements 68 extend less than 360 around the guide rail
62 so that the entire assembly may be withdrawn from the
guide rails at the upper end of the guide rail assembly.
25 When it is desired to remove the jet aeration assembly 20
from the tank, the assembly may be hoisted along the
guide rail by means of chain 70 which is fastened to the
motor assembly. So that solids or other debris do not
lodge in the upstanding air pipe 24 while the jet aeration
30 assembly 20 is being serviced, air discharge may be
maintained through the discharge pipe 24 while the jet
assembly is removed therefrom. The entire assembly may
be removed from the guide rails simply by raising it
above the support rail elements 64. After cleaning or
35 other maintellance service upon the retrievable jet
g
aeration apparatus, it may be lowered by means oE the
chain 70 along the guide rails until it is in the desired
position Eor operation as shown in FIGURE 1. In this
regard, it will be appreciated that the guide rail system
is adapted to direct the downwardly depending inlet
sleeve assembly 44, 46 into overlapping relationship with
the upstanding air delivery pipe 24. Moreover, the guide
rail and support assembly 60 is adapted to support the
weight of the jet assembly 20 iin operation, and further
0 to support the backward thrust directed by the assembly
against the guide rail sleeve elements 68.
As indicated, the interaction of the downwardly
directed secondary inlet sleeve and the upwardly directed
air pipe is an important feature of the apparatus of
~5 F~GURE 1. In this connection, illustrated in FIGURE 2 is
an embodiment 200 of a nozzle assembly similar to that
illustrated in FIGURE 1 which illustrates the various
dimensions of the embodiment 200, which is shown substan-
tially to scale in the illustration of FIGURE 2. The
2a illustrated nozzle assembly is constructed in a unitary
manner from smooth surfaced fiberglass reinforced
polyester plastic and comprises a connection flange 202
~or connection to the discharge of a suitable pressurize
motive Eluid source. The nozzle assembly further includes
25 a right cylindrical mixing chamber section 204 having a
diameter Dl of 6 inches, and an elliptical nozzle
projecting thereinto and having a discharge diameter LD
o~ 3.5 inches. Projecting downwardly from the mixing
chamber cylinder 204 and in unobstructed communication
30 therewith is a secondary fluid inlet flange 206 which has
a diameter D3 at its intersection with with the cyl-
indrical mixing chamber section 204 of 6 inches, which is
the same as t:hat of the cylinder 204. The secondary
fluid inlet flange projects downwardly from the mixing
35 chamber cylinder 204 a distance of 7 inches in the
-- 10 --
illustrated embodiment, thereby providing for a hydro-
static head which may be introduced into the mixing
chamber of approximately 7 inches of water. As further
indicated on the drawing, the downwardly projecting
secondary fluid inlet flange flares outwardly to an inlet
diameter D4 of about 8 inches, to assist the telescopic
insertion of a coacting upstandling air inlet pipe there-
into, which may have an outer cliameter in the range of
from about 4 to 5 inches. The illustrated mixing chamber
1~ cylinder 204 is 10 inches long with the downwardly
depending secondary fluid inlet: sleeve being centered
along the mixing cylinder 204. At the downstream end of
the mixing cylinder 204, a converging section 208 having
a length of 4 inches and a downstream diameter D2 of 4.9
15 inches connects to a cylindrical float section 210 having
a length of 2 inches, and an outlet discharge orifice D2
of 4.9 inches. In the illustrated embodiment 200, the
secondary fluid inlet into the mixing chamber has a
minimum cross sectional area which is substantially
20 greater than the discharge cross sectional area of the
disch~rge orifice 212.
Various aspects of the present methods and
apparatus may be embodied in a broad variety of configu-
rations of wastewater treatment systems. In this regard
~5 or example, illustrated in FIGURE 3 is a sludge holding
tank aeration system 300 comprising a sludge holding tank
302 which may be suitably constructed of reinforced
concrete, and a retrievable aeration apparatus 304. The
illustrated aeration apparatus 304 comprises a blower 306
30 for providins pressurized air ~ithin the tank 302, an
upper guide rail holding assembly 308 which is adapted to
support guide rails 310, 312 and a submeeged jet aeration
appartus 320 which is shown in cross section in FIGURE
~. The jet aeration apparatus 320 may be readily lifted
3~ along the guide rails 310, 312 and withdrawn from service
~Z~S3
for maintenance, inspection and cleaning. The blower 306
may be left in operation while the jet aeration appartus
320 is removed in order to prevent collection of sediment
or other solids therein. In any event, the blower 306
may be turned on so that the upwardly extending pipe 340
may be cleared before guiding of the jet aeration assembly
into telescoping relationship therewith. In operation,
the guide rail assembly base support provides vertical
support for the pump and nozzlle assembly and provides
10 horizontal thrust support for the backward thrust of the
jet which is directed into the ~ankage fluid.
The embodiments o~ FIGURES 1-4 utilize single
nozzle jet aeration construction. Illustrated in FIGURES
5-B are embodiments of treatment apparatus which utilize
1~ multipl~ discharge nozzle systems. In this connection,
illustrated in FIGURES 5 and 6 is a wastewater treatment
apparatus 500 which comprises a wastewater treatment tank
502 of plug flow design, and a retrievable jet aeration
assembly 504 having a plurality of discharge nozzle
20 elements 506, 508, 510, 512 having radially differing
discharge directions. As illustrated in FIGURE 5, the
retrievable aeration assembly 504 comprises an above
~ater guide rail support ~rame 514 which supports the
vertically aligned guide rails 520, 522, particularly in
25 respect to outwardly directed thrust, and are constructed
in such a manner that the jet aerator assembly may be
vertically lifted therefrom and removed for servicing.
The system 500 further comprises a pressurized air inlet
conduit 522 which may be connected at its upstream end to
30 a suitable blower (not shown). As shown in FIGURE 6,
which is a cross sectional view taken through llne 6-6 of
FIGURE 5, the pcessurized air conduit 522 is firmly
mounted at the bottom of the tank 502 and is provided
with an upwardly projecting discharge conduit 530, which
35 projects a precletermlned distance from the bottom of the
~ZS~i3
tank for appropriate interaction with the multiple nozzle
jet aeration assembly 504. In this regard, the retriev-
able multiple nozzle jet aeration assembly is provided
with a single submersible pump unit 542 and a single
downwardly projecting sleeve 544 for making a hydrostatic
seal with the upwardly projecting air pipe 530. The
pressurized fluid from the pump 542 is directed through a
multiple nozzle jet aeration structure 532, and the air
introduced into the multiple nozzle assembly through
~0 downwardly projecting sleeve 544 is conducted in an
appropriate manner to the multiple motive stream nozzles
in accordance with conventional jet aeration technology.
The combined primary and secondary fluid motive streams
are discharged at an angle having a downward component
5 into the wastewater to be aerated through the multiple
oriices of nozzles 506, 508, 510 and 512.
Illustrated in FIGURES 7 and 8 is a wastewater
treatment apparatus 700 which comprises a wastewater
treatment tank 702 of plug flow design, and a retrievable
~0 jet aeration assembly 704 having a plurality of discharge
nozzle elements 706, 708, 710, 712 disposed along a
common maniold 714. As illustrated in FIGURE 5, the
retrievable aeration assembly 704 comprises an above
water guide rail support frame 716 which supports the
25 vertically aligned guide rails 720, 722. The rails 720,
72~ are constructed so that the jet aerator assembly may
be vertically lifted therefrom and removed for servicing,
as previously discussed. The system 700 further comprises
a pressurized air inlet conduit 722 which may be connected
30 at its upstream end to a suitable blower (not shown). As
shown in FIGtlRE 8, which is a cross sectional view taken
through line 8-8 of :FIGURE 7, the pressucized air conduit
722 is eirmly mounted at the bottom of the tank 702 and
i5 provided with an upwardly projecting discharge conduit
3~ 730, which pro~ects a predetermined distance from the
- 13 -
bottom of the tank for appropriate interaction with the
multiple nozzle jet aeration assembly 704 and manifold
714. In this regard, the retrievable multiple nozzle jet
aeration assembly is provided with a single submersible
pump unit 742 and a single downwardly projecting sleeve
744 for making a hydrostatic seal with the upwardly
projecting air pipe 730. The pressurized fluid from the
pump 742 is ultimately directedl through multiple nozzles,
and the air introduced into the multiple nozzle assembly
1~ through downwaraly projecting sleeve 544 is conducted in
an appropriate manner to the multiple motive stream noz-
zles in accordance with conventional jet aeration
technology. The combined primary and secondary fluid
motive streams are discharged downwardly into the tank
through the multiple orifices of nozzles 506, 508, 510
and 512.
~ hile the present invention has been particu-
larly described with respect to certain specific embodi-
ments, it will be appreciated that various modifications
and alterations will become apparent from the present
disclosure, which are intended to be within the scope of
the present invention defined by the following claims.
