Liquid aeration device and method

In the treatment of livestock waste, liquid to be aerated is pumped from a storage container, holding pond or lagoon and drawn through a magnetic air inductor inlet then pumped into a conical chamber towards an outlet port at the narrow end of each of a series of conical chambers. Air is drawn into the chamber by pressure differential and intermingled with the liquid and waste to be treated to hydrolyze the fines as the material passes through the chambers. A conically shaped expansion cone attached as an extension of each chamber outlet port permits further expansion and intermingling of the air and liquid waste mixture. An open-ended sleeve is attached in surrounding relation to the outlet of each discharge cone so that the air/liquid stream from each cone is directed axially through its sleeve, each sleeve having a spiral baffle plate extending along the interior length thereof to further promote agitation of the mixture and most complete aerobic digestion of the fines.

CROSS-REFERENCE TO RELATED PATENTS 
U.S. Pat. No. 3,892,499, entitled CONVERSION OF ANIMAL WASTE, and 4,338,337 
entitled METHOD FOR RECOVERING AND RECYCLING ANIMAL WASTE MATERIALS, by 
Gerald P. Frankl, are directed to system environments in which the present 
invention is particularly useful. 
SPECIFICATION 
This invention relates to novel and improved methods and apparatus for 
livestock waste treatment and the recovery of useful feed values 
therefrom. More particularly, the present invention relates to apparatus 
and methods of aerating liquids in livestock waste treatment systems and 
is particularly useful for storage containers or holding ponds requiring 
reduction of biological oxygen demand (BOD) and hydrolization of fines in 
waste treatment facilities. 
BACKGROUND AND FIELD OF THE INVENTION 
The prior art devices adapted for use in aeration of waste materials have 
predominantly employed spargers, such as, perforated pipe and the like for 
releasing the oxygen bearing gas in the bottom of the storage tank or 
holding pond. The dispersion of the released gases from the sparger 
occasionally is further agitated by rotating vanes or multiple level 
baffles within the storage tank. For example, an arrangement for 
introducing the oxygen bearing gas in line with a propeller agitator is 
shown in U.S. Pat. No. 3,865,721 to Kaelin. Other efforts to directly 
agitate a fluid by releasing pressurized gas below the fluid surface and 
into flow directing columns are shown in U.S. Pat. Nos. 1,574,783 to Beth, 
3,043,433 to Singer and 3,446,488 to Mail et al. 
It has also been known for some time to use a pressure differential 
injector for drawing gas into a liquid stream as is shown in U.S. Pat. No. 
1,430,303 to Hartman while similar such injector/mixer apparatus for other 
applications are shown in U.S. Pat. Nos. 3,243,046 to Kakumoto et al and 
214,090 to Bott. Although specifically concerned with steam condensation, 
the device of Bott includes a spiral ridge arrangement within the outlet 
horn. Other patents of interest are U.S. Pat. Nos. 2,479,403 to Powers, 
3,306,449 to Minigishi, 3,833,719 to Kuerten et al, 3,671,022 to Laird et 
al, and French Pat. No. 452,874. 
The use of spargers and other devices in oxygenation of wastes generally 
recognizes that a larger bubble which tends to rise rapidly to the surface 
of the liquid expels much of its liquid treating contents (usually oxygen) 
uselessly into the atmosphere. Thus it is important that the gas be 
reduced to bubbles of the smallest possible size prior to release thereby 
permitting a higher percentage of the oxygen content within the bubbles to 
be transferred into the liquid. In providing oxygen for an aerobic system, 
air flow as is generally measured in cubic feet per minute (cfm) is highly 
important as it requires approxiamtely 65 cubic feet of air for each pound 
of oxygen. A traditional rule of thumb relative to mechanical areation 
systems is that two pounds of dissolved oxygen (DO) per horsepower hour is 
the expected level of recovery through such prior art systems and the 
economic penalty for aerobic digestion of wastes generally has increased 
as power costs have increased. Further, the power requirements to overcome 
the hydraulic head of relatively deep containers or storage ponds, such 
as, up to a depth of about 20 feet often pose further economic 
disadvantage for the prior art diffuser systems. Venturi-type devices for 
intermingling of gases and fluids, such as, Minigishi have been more for 
the purpose of agitation accomplished by release of the air bubbles at the 
surface and have not been accepted for meeting the continuous 
emulsification and large volume mixing demanded by waste treatment 
facilities. 
Accordingly, there has been a continuing need for economic and efficient 
methods and apparatus of gas/fluid intermingling adequate to meet the 
demands for odor control as in the use of anaerobic ponds and especially 
to meet the stringent regulations concerning effluence entering rivers and 
streams. In this same relation, it has been recognized that magnesium 
phosphate deposition on metal surfaces is a particular problem in the 
course of recycling anaerobic liquid from animal waste treatment lagoons; 
and, if not properly controlled, there is a tendency for the particles to 
collect and form a scale on the pump impeller and other surfaces through 
which the liquid is directed so as to impose severe limitations on the 
life of the equipment and to some extent affect the quality of digestible 
protein recovered. Various magnetic and electromagnetic collectors have 
been employed either alone or in connection with chemical flocculating 
agents to remove metallic or mineral particles in liquids but none devised 
for use in association with a pump impeller or submersible inductor 
assembly so as to create a magnetic field across an inlet passage for the 
removal of particles from animal waste material so as to enhance the 
efficiency and performance of the inductor assembly in the aerobic 
digestion of fines in the material and conversion into single cell 
protein. Representative patents of interest are U.S. Pat. Nos. 3,697,420 
to D. S. Blaisdell et al; 3,714,037 to G. C. Almasi et al; 3,936,376 to P. 
Centineo; 3,998,741 to G. D. Councell; 4,278,549 to J. L. Abrams et al; 
4,279,748 to K. Inoue; 4,289,621 to J. R. O'Meara, Jr.; and 4,299,700 to 
C. H. Sanderson. 
SUMMARY OF THE INVENTION 
In the present invention, improved submersible magnetic air inductor method 
and apparatus have been devised for effectively intermingling air or 
oxygen-augmented gases with a liquid or liquids and solids present in 
livestock waste treatment facilities in such a way as to render more 
efficient the hydrolization of fines and aerobic digestion of the single 
cell protein into the waste. The present invention employs a vacuum 
principle below the surface of the liquid so that the air is motivated in 
a manner which does not require the energy to overcome head pressure 
normally encountered in transferring the air below the surface of the 
liquid. The air is impregnated and emulsified with the liquid being pumped 
and discharged into the container or pond. The air is motivated through 
the liquid in a manner which effects greater volumes of intermingling than 
available with the prior art devices, the air being broken into fine 
particles so as to increase the exposed surface thereof relative to the 
liquid for a given quantity of air. Further, the invention is particularly 
useful for a relatively wide range of liquid depths, such as, five to 
twenty feet below the surface through a submersible pump forcing liquid 
into a vacuum-creating mixing chamber in association with the air. This 
minimizes the horsepower normally required to overcome head pressures at 
these depths. The gas which can be air at atmospheric pressure can be 
introduced unaugmented into the submerged mixing apparatus or can be 
supplemented by relatively lower power air pumps capable of applying four 
to ten inches of static pressure on the air conduit. 
In one form of air and liquid intermingling apparatus, an injector assembly 
includes a hollow conical member which has opposed wide and narrow open 
ends with the wide end receiving pressurized liquid for discharge as a 
stream from the narrow end. The injector assembly also includes a second 
conical member which is preferably formed as a shroud completely enclosing 
the first conical member and is mounted in coaxial relation to the first 
conical member but with its narrow end parallel with but axially spaced 
from the narrow end of the inner conical member. Thus, the gas is 
introduced into surrounding relation to the discharge stream as it expands 
upon exiting from the first member. That is, the space between the narrow 
open ends in conjunction with the conical member forms a mixing chamber 
for the gas and liquid. By dimensioning the second member narrow end about 
twice the size of the first member narrow end, expansion of the liquid 
discharge stream is assured thus effecting motivation of the gas into 
intermingled relation for further discharge with the liquid. The injector 
assembly also includes a third hollow conical member with its narrow end 
attached to the second member narrow end for forming an axially aligned 
but outwardly directed expansion chamber or diffuser. 
In another form of invention, a submersible induction assembly has a common 
impeller which draws the liquid and solid waste mixture through an inlet 
passage in which a magnetic field is established to effectively 
precipitate and remove metallic particles from the wastes which otherwise 
tend to form scale within the impeller and inductor sections. The impeller 
discharges the wastes through one or more Venturi-shaped inductors which 
radiate outwardly from the common impeller and at a flow capacity to 
generate a negative pressure condition which will encourage the 
intermixture of the air with stream of wastes from the liquid storage 
container for complete intermingling together. The air bubbles formed are 
further divided and retained in the mixture by passing the stream through 
enlarged, horizontally directed agitator or mixer sleeves defining outward 
radial extensions of the inductors. A region of reduced pressure formed at 
the entrance to each sleeve and in open communication with the sleeve 
interior causes a recirculatory movement of the aerated stream discharged 
by each sleeve so as to encourage the retention and entrainment of bubbles 
within the stream and thereby realize maximum aerobic digestion and 
hydrolization of the solid fines carried in the waste material. This 
aerated material is then recycled through a waste confinement facility for 
admixture with additional wastes, such as, a hog barn. The resultant 
mixture then undergoes separation by removal or separation of the moisture 
and selected fines containing the digestible protein nutrients which are 
delivered back into the waste material lagoon or pond. The solid waste 
materials and retained moisture not separated are collected and stored for 
use as feed values in accordance with the teachings of my hereinbefore 
referenced U.S. Pat. No. 4,338,337. 
An additional and advantageous feature of this invention relates to the 
mixer sleeve or spiral diffuser which allows large amounts of air to be 
drawn from the surface to be impregnated, emulsified and mixed with a 
large volume of water drawn through that sleeve. Preferably, an elongated 
hollow sleeve which is open at each end is mounted so that the injector 
outlet stream is directed into the sleeve interior from one end and with 
the end of the sleeve around the injector outlet being in open 
communication with the sleeve interior around at least a portion of the 
periphery of the injector. This permits passage of liquid from the storage 
container or pond into the sleeve interior from the injector mounting end 
of the sleeve. Accordingly, the liquid is drawn into the interior of the 
sleeve by the injector outlet stream and the air is intermingled with the 
liquid during passage through the sleeve. 
By the unique apparatus and method of the present invention, 75 pounds to 
100 pounds of DO per hp hour is possible. Accordingly, the invention is 
economically attractive for oxygenation or treatment of anaerobic ponds 
and the like. It is likewise possible to attach a series of the vacuum 
motivating mixers and/or mixer tubes from common manifolds of hydraulic 
pressure and/or air chambers. Embodiments of the present invention have 
been shown to be capable of performing 10% better than existing sparger 
devices with one-third or less power requirements. 
It is therefore an object of the present invention to provide for novel and 
improved apparatus and methods for obtaining maximum intermingling of air 
bubbles within a relatively large volume of liquid. 
It is another object of the present invention to provide a novel and 
improved apparatus and method for efficiently aerating a liquid in a 
container, storage pond or the like with minimal power demands. 
It is a further object of the present invention to provide for a novel and 
improved magnetic air inductor assembly for use in a waste treatment 
lagoon which will inhibit the formation of scale in the assembly while 
maximizing the oxygenation of waste containing liquids so as to encourage 
the retention and entrainment of bubbles within the liquid and thereby 
realize maximum aerobic digestion and hydrolization of solid fines carried 
in the waste as a preliminary to recycling of the aerated material through 
a waste confinement facility for admixture with additional wastes and 
subsequent separation by removal of moisture and selected fines from the 
wastes and returned in the form of digestible protein nutrients back into 
the waste treatment lagoon. 
Yet another object of the present invention is to provide for novel and 
improved methods and apparatus for maximizing emulsification of gas 
containing liquid treating elements into a liquid at locations below the 
liquid surface in a manner which requires minimal power for communicating 
with the gas to the point of emulsification with minimum or no gas 
augmenting power requirements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring in more detail to the drawings, in the perspective view of FIG. 1 
an aeration device 10 in accordance with the present invention is shown 
submerged within a storage tank 12 containing a liquid 14 which might 
typically be water containing elements requiring treatment including 
suspended solids. Although a tank 12 is shown for illustration purposes, 
it will be readily recognized that the present invention is equally well 
suited for use with the liquid storage environment, such as, holding 
ponds, lagoons or the like and can even be employed in a moving liquid 
environment as in canals, streams or other environments. The present 
invention is particularly useful for efficient livestock, poultry or 
municipal waste oxidizing. Thus, it finds application for large swine 
operations wherein the swine waste is periodically flushed from a barn by 
pumping liquid from a treated lagoon, storage tank or the like through the 
barn and returning the waste back into the storage container where it is 
treated aerobically by the present invention. In conjunction with poultry 
waste treatment, large volumes of volatile ammonia-type nitrogen can be 
converted into nitrates by the present invention wherein the nitrogen is 
stable and odorless for use as a fertilizer. Ammonia conversion to 
nitrates generally requires approximately 4.57 pounds of DO per pound of 
ammonia. For municipal waste treatment facilities, the present invention 
is particularly useful from a standpoint of BOD, suspended solids and 
grease flotation requirements. 
The embodiment shown in FIG. 1 includes a single-ended aeration assembly 10 
which is coupled to be provided with air via a conventional flexible but 
circumferentially rigid hose 15. The aeration device is primarily 
motivated by a submersible pump 16 which is electricaly powered via cable 
17. For convenience, submersible pump 16 is shown resting directly upon 
the bottom of tank 12 although with hose 15 and cable 17 being generally 
retained in a generally vertical position by a flotation device 18. Pump 
16 withdraws liquid from its immediate environment and introduces it into 
a vacuum generating injector arrangement generally similar to that which 
will be described subsequently for one end of the FIG. 3 embodiment and 
injects this pressurized fluid into an outlet orifice which is directed 
generally coaxially into mixer tube or sleeve 20. As will be more readily 
apparent from the subsequent description, the outflow 21 from the aerator 
will contain fine particles of air bubbles which maximizes the oxygenation 
of the material within the tank 12 as these bubbles rise to the surface of 
liquid 14. Although the present invention will operate satisfactorily for 
many purposes with hose 15 merely vented to the atmosphere, it has been 
found that the efficiency can be further increased by a blower 22 which is 
powered by a low horsepower drive motor 24 to increase the air pressure 
within hose 15. The air introduced to hose 15 can be air drawn directly 
from the atmosphere or can be oxygen supplemented, such as, by ozone or 
aran generators. Submersion pump 16 can be suspended at any level within 
tank 12 and can obviously be positioned to augment rotary churning of the 
contents of tank 12 if desired. Further, pump 16 can be mechanically 
motivated from the surface as is generally shown in said U.S. Pat. No. 
3,892,499 cross-referenced above, or by any of various known alternatives. 
FIG. 2 shows a perspective view of a double-ended aeration device in 
accordance with the present invention wherein a pair of aeration 
assemblies 30 and 31 are arranged in back-to-back configuration. Air, 
oxygen, ozone, aran or any suitable gas depending upon the treatment to be 
effected in the liquid is introduced to the aeration assemblies 30 and 31 
via common coupling 32 to pipe connections 33 and 34 as is shown in 
somewhat greater detail in FIG. 4. 
Submersible pump 35, electrically powered via cable 36, is a heavy duty 
pump with the impeller contained within housing 36 and directly attached 
to the output shaft of drive motor 37. The impeller in housing 36 drives 
liquid drawn from the environment of pump assembly 35 into outlet 
connection 38 for common motivation coupling to both aeration assemblies 
30 and 31. As will be more fully appreciated from the detailed description 
of a similar double-ended aeration version as shown in FIGS. 3 and 4, the 
liquid under pressure is split in common portion 39 and directed outwardly 
into aeration assemblies 30 and 31 for mixing with the gas communicated 
through connectors 33 and 34. 
A typical conventionally available submersible pump useful in conjunction 
with a double-ended aerator using a 1.25 inch inner cone orifice is a 
Model SE 151 1.5 hp Peabody Barnes pump. This pump is equipped with 
ceramic seals as well as secondary exclusion seals to retain oil. The 
ceramic and carbon seals withstand the acids and gases characteristic of 
waste materials being aerated. The motor 37 output shaft is typically 
stainless steel for the same reason and corrosion resistant materials are 
generally employed throughout. The intake for pump 35 is typically from 
below the impeller housing 36 and thus support legs, such as, 40 and 41 
are employed if the pump assmebly 35 is to be positioned on the bottom of 
the storage pond or tank or the like. 
The double-ended embodiment of the present invention shown in FIGS. 3 and 4 
is internally identical to the FIG. 2 device. FIG. 3, a top plan view of 
this embodiment, shows input connection 45 adapted for attachment to a 
submersible pump similar to that mentioned hereinbefore as via elbow 
connector 46. Thus, liquid under pressure is commonly introduced to 
splitter chamber 47 wherein it is directed into aeration assemblies 48 and 
49. The pressurized liquid is introduced to a nozzle, such as, 50 formed 
as a segment of a cone so that the fluid is discharged through the port or 
orifice formed at the narrow end 51 thereof. Inner cone 50 is preferably 
formed to produce a flow velocity increase and resulting pressure decrease 
along its length as by maintaining the diameter of the opening 44 at the 
wide end about four times the diameter of the narrow end opening 51. 
Preferably, cone 50 should be of as long an axial length as possible, an 
axial length of about eight times the diameter of orifice 51 having been 
formed to be suitable for this purpose. 
Inner cone 50 is shown completely surrounded by a shroud assembly including 
a cylindrical portion 52 and an outer conical portion 53 formed as a 
continuation of cylinder portion 52. Outer cone 53 terminates in an outlet 
port 54 at the narrow end thereof in spaced relation to port 51 so as to 
define an intermediate mixing chamber 55. The high velocity liquid flow 
discharging from port 51 into chamber 55 tends to expand and decrease in 
velocity so as to draw the air into intermingled relation therewith. The 
shroud assembly completely surrounds cone 50 so as to isolate chamber 55 
from the environment as is needed when the device is further submerged. 
However, only the terminal portion of conical section 53 need be included 
around port 54 if the device is operating so that the exterior environment 
is air or some other form of gas containing enclosure. 
FIG. 4 shows the means for charging the space between inner cone 50 and 
outer cone 53 with air wherein a conduit 56 is commonly coupled to 
connectors 57 and 58 which are thence attached to nipples 59 and 60. Thus, 
the air present in hose or conduit pipe 56 is in open communication with 
the space between cones 50 and 53 so that discharge of the liquid from 
port 51 into chamber 55 effects a venturi-like gas motivation into mixer 
chamber 55. Note further that port 54 is dimensioned larger than port 51 
so that the pressurized liquid discharged from cone 50 tends to expand and 
slow somewhat as it passes through chamber 55 thereby providing both 
withdrawal of air from pipe 56 and intermingling with the liquid at an 
initial stage. The distance between the discharge end 54 and orifice 51 
created by the air chamber column correlated with the difference in size 
of orifices 51 and 54 accommodates the flow of liquids from inner cone 50 
which slows down and expands to fill outer orifice 54 and in passing 
through outer orifice 54 creates a vacuum for withdrawing the air or other 
gas from the space between cones 50 and 53. Each aerator assembly 48 and 
49 termiantes in a somewhat bell-shaped cone or horn, such as, 61 
extending from port 54. Cone 61 is flared outwardly to allow the stream 
discharged therein to continue expanding and further slow until it reaches 
the flange collar 62 to which the mixer tube, such as, 63 and 64 are 
attached and as will be described in greater detail for FIGS. 5-8. This 
arrangement allows a maximum force of the liquid being pumped from the 
vacuum aeration devices 48 and 49 to be exerted in the center of the mixer 
tubes 63 and 64 causing a maximum amount of circulation and pumping action 
through these mixer tubes thereby emulsifying the air and mixing it with 
an increased and larger volume of liquid. The embodiment of FIGS. 3 and 4 
is further adapted for attachment to a support (not shown) as by stanchion 
65 in the event that the submersion pump does not provide sufficient 
mechanical support. 
A typical mixer tube or spiral baffle 70 useful in conjunction with the 
present invention is illustrated in FIGS. 5-8. Although shown as an 
attachment to a vacuum pump apparatus as discussed above, it will be 
recognized that the tube 70 can be used in shallow flows without the 
specific vacuum pump apparatus by merely discharging high volumes of air 
coaxially into the center of tube 70. That is, air under ten inches of 
static pressure which can be provided by a 5 hp motor can be sufficient 
for air-to-liquid intermixing with the sleeve-type mixer tube 70 for 
depths of a few feet. Such a pressure is adequate for creating a hydraulic 
pumping action moving large volumes of liquid through mixer tube 70 so as 
to emulsify and mix this air with large volumes of water. 
Mixer tube 70 is formed with an elongated cylindrical sleeve 71 which is 
open at both ends 72 and 73. Attached in proximity to end 72 is a collar 
74 which positions a plurality of radial posts 75-78 which further 
position clamping collar 80 in a generally centered relation within end 72 
of cylindrical sidewall 71. Collar 80 has radially projecting ears 81 and 
82 thereon adapted to be flexed in gripping relation by bolts or the like 
(not shown). Thus, a vacuum discharge nozzle such as is shown in FIG. 5 
can be gripped and retained in coaxial discharge relation relative to the 
interior of cylindrical sleeve 71. 
An elongated plate 86 is formed as a generally radial extension from the 
interior wall of cylinder 71 and formed in spiraled relation as is 
illustrated in FIGS. 5, 7 and 8 so as to effectively form a single 
complete revolution around the inner sidewall of cylinder 71 throughout 
its length. Accordingly, it can be seen that fluid is drawn through the 
open end 72 into the interior of mixer tube 70 via the motivating stream 
from nozzle 84. The mixture of this fluid and the gas from nozzle 84 is 
thoroughly emulsified by the churning action of flange plate 86 as it 
passes through the length of tube 71. The discharge from outlet end 73 
will contain a thorough mixture of fine gas particles which is ideal for 
aeration or oxygenation purposes. 
The diameter of mixer tube 70 depends upon the viscosity of the liquid to 
be aerated and the apparatus employed to propel air into it. As a general 
guideline, the diameter of tube 70 waste water treatment can be selected 
according to the following: For water containing no more than 2% 
solids--8.0 inch diameter; for water with roughly between 2% and 4% 
solids--10.0 inch diameter; and for water containing greater than 4% 
solids--12.0 inch diameter. The axial length of tube 70 is preferably as 
long as possible but not long enough to create back pressure which reduces 
the liquid flow from the stream producing device. Thus, for an 8.0 inch 
diameter sleeve 71, a length of two feet has been found experimentally to 
be optimum for most applications and is also considered to be a 
satisfactory length for the larger diameter. 
In use for a typical installation employing a double-ended embodiment, the 
conical vacuum mixer assemblies are attached to a submersible pump and an 
air hose coupled to the divider chamber. The thus assembled elements are 
either lowered to a preselected depth in suspension within the liquid to 
be aerated or allowed to descend to the floor of the container. The 
submersible pump is then energized so as to pressurize fluid from the 
container for injection as a stream into the conically shaped mixing 
chambers and towards the outlets thereof. The gas containing elements 
intended for interaction with the liquid is coupled as via the air hose 
either with atmospheric pressure or with relatively light pressure 
augmentation. The fluid stream is expanded as it discharges into the 
conical mixing chamber to provide an initial intermixing with the gas. The 
discharge stream is then introduced into the elongated, open-ended 
diffuser tube where additional liquid is introduced for further 
intermixing with the discharge gas. By confining the outlet flow through 
the length of the mixer tube and further by spiraling this flow, an even 
more thorough and efficient gas-to-liquid intermixing is effected. 
Typically, the submersible pump is allowed to operate for extended 
periods, it having been found that a storage tank for flushing a 
confinement feeding barn for livestock can be sufficiently aerated by 
continuous operation of the pump so that the liquid contents can be 
employed for flushing of the confinement area on a regular basis, such as, 
once each day. 
In a typical double-ended mixer in accordance with the present invention 
and as is shown in FIGS. 3 and 4, the overall length between the outlet 
discharge openings (i.e., 66 and 67) is about thirty-eight inches with the 
discharge openings 66 and 67 being each 4.0 inches, the mounting collar 62 
having an axial length of 2.0 inches, the bell-shaped expansion cone 61 
having an axial length of 3.0 inches. Port 54 is axially spaced from 
outlet 51 by 2.0 inches and, for one model, has a diameter of 2.0 inches 
for a 1.25 inch diameter of outlet 51 whereas, for yet another model, 
orifice 54 has a 1.75 inch diameter for a 1.0 inch diameter of outlet 51. 
Cylindrical sleeve portion 52 of the outer shroud is typically 3.25 inches 
in length and the wide end of the inner cone 50 is typically 4.0 inches in 
diameter. The overall length for the outer shroud up to port 54 is 10.0 
inches while the axial length of the inner cone 50 is 8.0 inches. The 
splitter chamber 47 is typically about 8.0 inches in axial length and 
coupled through a 3.0 inch diameter connection through fitting 45 to a 1.5 
hp Peabody Barnes submersible pump when outlet 51 is a 1.25 inch diameter 
or a 0.5 hp to 0.75 hp pump when outlet 51 is 1.0 inches in diameter. A 
6.0 inch air hose 56 is employed and couples into 2.50 inch diameter air 
connectors 59 and 60. The inner surface of the inner cones is preferably a 
hard surface, the elements of the vacuum mixers are predominantly formed 
of 0.25 inch HR stainless steel. 
A typical mixer sleeve 70 is formed from 18 gauge stainless steel with an 
overall length between openings sufficient to insure confinement of the 
discharge stream without significant back pressure, a length of 24.0 
inches having been found experimentally to be satisfactory in this regard. 
The mounting flexible collar 80 probably has a minimal 4.0 inch inside 
opening and a 0.5 inch spacing between 1.0 inch clamping ears 81 and 82. 
The inner collar 74 is likewise of 18 gauge stainless steel (as is collar 
80) but with an axial length of 3.50 inches and with 0.375 inch diameter 
spacer rods 75-78. The diameter of cylinder 71 is selected in accordance 
with the liquid viscosity and solids content as discussed previously with 
a 4.0 inch diameter outlet centered therein via clamping collar 80 so that 
a 2.0 inch radial spacing is maintained around the entire outer periphery 
of the discharge stream producing outlet. The spiral fliting or flange 
plate 86 is of 18 gauge steel with a radial extension into the interior of 
cylinder 71 typically between 0.25 and 1.0 inches depending upon the 
diameter of tube 71. The radially inward projection of plate 86 is 
selected so as to develop a rotational churning effect on the discharge 
stream but without introducing any significant back pressure to the 
discharge stream producing apparatus. It has been found experimentally 
that a radial inward extension of 0.625 inches can be used for an 8.0 inch 
diameter of tube 71 and 0.75 inches for a 10.0 inch tube. Thus, it is 
believed that an ideal ratio of radial inward height of plate 86 to the 
diameter of tube 71 is in the range of 0.07 to 0.08. Using models 
dimensioned as discussed, better than 25 pounds of DO per hp hour is 
possible with up to 20 feet in depth for oxygenation of waste materials. 
Using an atmospherically vented hose rather than with any pressure 
augmentation of the air, approximately 50% of the air capacity for mixing 
can be obtained with the double-coned vacuum mixers and mixing tubes. 
However, a blower, such as, 22 in FIG. 1 made of a 16 gauge housing and 
with balanced, self-spinning paddle-type wheels powered by between a 1/3 
hp and 1 hp motor, the volume of air and liquid mixing is significantly 
enhanced. A typical such blower has an air inlet of five to six inches in 
diameter as a flanged opening in the housing in the center of the 
paddle-type wheel. The wheel is 10.625 inches in diameter with paddles 2.5 
inches wide mounted directly on the shafts of the motor. A 1 hp motor at 
3450 rpm delivers 370 cfm with six inches of static pressure. The size of 
the motor used on the fan can be varied to fit various applications and 
depths of aerator placement. A 1/3 hp motor at 3450 rpm with such a blower 
typically delivers 335 cfm with four inches of static pressure. 
Although single and double-ended embodiments of the vacuum aerator 
assemblies have been shown and described, it will be recognized that a 
plurality of such aerators can be extended from a common manifold 
energized by a single pump and receiving air individually from a 
manifolded air chamber charged with a single blower. In an experimental 
research application for a municipal sewage treatment plant, four 
double-ended vacuum aerators each powered by a 1.5 hp submersible pump 
were all charged from a single 3 hp blower. These four aerators using less 
than 10 hp total power were assigned 25% of the sewage treatment for that 
municipality. The contemporary municipal equipment for the other 75% of 
the municipal sewage required 100 hp of power. Despite the fact that less 
than 1/3 of the energy requirements were demanded by the aerators in 
accordance with this invention, a significant improvement in resulting 
reduction of grease content, suspended solids and BOD were obtained 
through the present invention as contrasted to the contemporary equipment 
and further despite the fact that approximately 11.3% greater flow was 
handled through the channels employed with the present invention as 
contrasted to the average flow of the other canals. The confinement area 
flushing mentioned between page 16, line 30 and page 17, line 4 hereof can 
be via intermittent flushing of limited quantities from the storage tank 
throughout the day or can be "surge" flushing (i.e., once per day) of 
greater quantities from the storage tank. 
DESCRIPTION OF ALTERNATIVE EMBODIMENT 
Referring to FIGS. 9 and 10, a modified form of aeration assembly similar 
to that illustrated in FIGS. 2 to 4 has a pair of aeration assemblies 30' 
and 31' arranged in diametrically opposed relation to one another at the 
discharge of a submersible pump 36' which includes common impeller 38' 
within the housing 38" and driven by a motor 37' mounted on the impeller 
housing 38". Thus, as opposed to directing liquid discharged by the 
impeller 38' through an intermediate splitter chamber into the aeration 
assemblies as in the form of FIGS. 2 to 4, the aeration assemblies are 
joined directly to the impeller housing 38". Here, the housing 38" is 
characterized by being of open, generally cylindrical configuration and, 
in cross-section, has an upper flat horizontal wall portion 90 and a lower 
generally bowl-shaped wall portion 91 which inclines upwardly and radially 
outwardly from a common central inlet 92 directly beneath the impeller 
38'. Thus, the wall portions 90 and 91 effectively converge toward one 
another in a radially outward direction and terminate in diametrically 
opposed flanges 93 to facilitate attachment of the aeration assemblies 30' 
and 31' thereto in a manner to be described. 
An important feature of the alternate form of invention resides in the 
manner in which liquid is drawn from the storage tank or waste treatment 
lagoon, not shown, through a magnetic field into the impeller housing 
whereby to cause agglomeration or precipitation of magnetizable particles 
in the liquid, such as, mineral or metallic elements which are commonly 
entrained in liquid animal waste material. To this end, an elongated, 
open-ended, generally cylindrical sleeve 94 defines an inlet passage 95 
extending parallel to the longitudinal axis of the sleeve, the passage 
being of generally rectagular cross-sectional configuration and having 
disposed therein a plurality of longitudinally extending, spaced plates 
96. The sleeve is relatively thick-walled, and the inlet passage 95 has 
top and bottom horizontal surfaces 97 and 98 with the spaced magnetic 
plates 96 positioned on edge intermediately across the passage with 
opposite edges of the plates permanently affixed to the top and bottom 
surfaces 97 and 98. Opposite sides of the passage 95 which flank the plate 
members 96 communicate with inclined passageways 99 which converge 
upwardly into the central inlet 92. Further, the central inlet 92 extends 
vertically through the upper wall of the inlet sleeve 94 to communicate at 
the center of the sleeve 94 with the inlet passage 95. 
The magnetic plates are arranged such that opposed vertical flat surfaces 
of each plate are of opposite polarity. Thus, the confronting or facing 
surfaces of adjacent plates are similarly of opposite polarity. In this 
manner, the magnetic plates 96 establish magnetic fields across the inlet 
passage 95 to precipitate or remove the mineral particles from the wastes 
which are drawn in from the waste treatment container into the impeller 
housing thereby greatly minimizing the formation of scale within the 
impeller housing and aeration assemblies and enhancing their performance 
and efficiency. Each of the aeration assemblies 30' and 30' comprises an 
inner cone 50' and outer concentric cone 53' having a venturi-shaped 
throat region 54' which diverges into an expanded conical discharge 
portion 61' surrounded by a mixer tube 64', and a conduit 56' introduces 
air from the atmosphere through branch lines 59' and 60' through the wall 
of the cone 53' surrounding the nozzle 50'. In the form of FIGS. 9 and 10, 
the nozzle 50' and conical portion 53' have a common flange 62' for 
connection to each flange 93 at the discharge end of the impeller housing 
90, the nozzle having a divergent or wider end adjacent to the flange 62' 
which is enlarged with respect to the discharge opening from the impeller 
housing 90, and the nozzle 50' converges away from the wider end to 
terminate in a narrow end or orifice 51' at the entrance to the venturi or 
throat region 54'. In this relation, the internal construction and 
operation of the individual aeration assemblies including the mixer tube 
64' correspond to that of the embodiment of FIGS. 3 and 4; however, as 
noted earlier, the aeration assemblies 30' and 31' are connected directly 
to the annulus of the chamber or housing 38" outwardly of the impeller 
38'. This relationship increases the flow capacity of the impellers in the 
discharge of waste directly from the impeller housing through the 
venturi-shaped conical inductors 53' whereby to generate a negative 
pressure condition across the venturi region 54' to draw the air into the 
stream of waste and to become entrained in the stream of waste in the form 
of air bubbles. These air bubbles are further divided as the stream is 
discharged into the mixer sleeves 64' and, in advancing through the mixer 
tubes, the intermixture of air and liquid waste will create a region of 
reduced pressure to cause recirculatory movement of the aerated stream 
discharged by each sleeve to further divide the air bubbles while 
maintaining the bubbles in the stream. This results in maximum aerobic 
digestion and hydrolization of the solid fines carried in the waste 
material. 
As illustrated in FIG. 11, the method and apparatus of the present 
invention has been found to be particularly useful in the conversion of 
animal waste into animal feed values. Here, a submersible magnetic air 
inductor assembly as illustrated in FIGS. 9 and 10 is suspended from a 
platform P to rest at the bottom of a waste treatment lagoon L. Aerated 
liquid waste material from the lagoon is pumped through delivery line 110 
to a waste confinement facility which typically may be a cattle barn or 
hog barn as illustrated at 112, the liquid waste material being employed 
as a flushing agent so as to carry animal wastes along gutters or flumes 
in the facility into a collector trough 111 and from which the waste-laden 
flush water can then be advanced via line 113 to a sump 114. The waste 
material is then pumped to one or more separator stages, for example, a 
shuttle-type separator 115 as set forth and described in my 
hereinbefore-referenced U.S. Pat. No. 4,338,337. This separator is capable 
of selectively removing a percentage of liquid and fines from the waste 
material to drain the same back into the lagoon L via return line 120. The 
larger solids which are collected from the separator stage may then be 
passed onto a conveyor and subsequently removed into a stacking area in 
the manner described in my U.S. Pat. No. 4,338,337. The magnetic air 
inductor assembly in the lagoon L is operative to induce air to flow from 
the surface through the aeration assemblies for intimate mixture with the 
liquids and solids making up the waste material whereby to recycle same 
throughout the lagoon and to circulate and uniformly distribute the air or 
oxygen in the form of microsized bubbles. In this way, the air is 
uniformly distributed throughout the liquid and fines recovered from the 
waste confinement facility so as to realize maximum aerobic digestion and 
hydrolization of the solid fines to convert them into single cell protein 
matter. Again, this material is recycled as flush water through the waste 
confinement facility for intermixture with additional wastes followed by 
separation of the moisture and fines in the separation stage and return of 
the digestible protein nutrients into the waste material lagoon. The 
larger solid materials and moisture not separated in the separation stage 
are then collected and stacked for use as feed supplement for the animals. 
The entire process of aeration, flushing and separation is preferably 
continuous and it is therefore extremely important that the process of 
aeration in the lagoon not be impeded or slowed by the collection or 
buildup of scale, particularly through the impeller and inductor regions 
of the assemblies. 
It is therefore to be understood that various other modifications and 
changes may be made in the preferred and modified forms of invention as 
herein set forth without departing from the spirit and scope of the 
present invention as defined by the appended claims.