CA1062381A - Aerobic sewage treatment unit - Google Patents

Abstract

AEROBIC SEWAGE TREATMENT UNIT

ABSTRACT OF THE DISCLOSURE
An aerobic sewage treatment unit including a main sewage collection tank having an inlet and an outlet is disclosed with a separate intensified micro-liquefaction tank of horizontal cylin-drical configuration being mounted above the main tank with tan-gential inlets and outlets at opposite ends; the inlet is connected to the output of a micro-liquefaction pump immersed in the main tank with the outlet from the intensified micro-liquefaction cham-ber retruning to the main tank; air flows into the pump down a hollow drive shaft to exit from a hollow impeller of S-shaped configuration. The material discharge from the pump flows through the intensified micro-liquefaction chamber being in a vortex due to the tangential inflow and outflow openings,

Description

~ ~ -This invention is in the field of sewage treatment equipment and is particularly directed to an aerobic sewage treatment unit having optimum aeration efficiency and being adaptable for converting an anaerobic sewage treatment unit to operate on the preferable aerobic process.
Septic systems employing the ~naerobic process are widely used in areas not having public sewage disposal facilities.
Generally, such sytems consist of a sewage collection tank, l usually referred to as a septic tank, in conjunction with a 10 ¦ drain field into which effluent from the tank is discharged.
Raw sewage normally flows by gravity into the septic tank where the solids gravitate to the bottom of the tank with liquid being discharged into the drain field to hopefully percolate downwardly into the surrounding soil.
lS The raw sewage received in septie tanks usually eon-tain organic constituents including protein, carbohydrates and .
fats, oxygen activated organisms whieh funetion bioehemiexlly to decompose the organie eonstituents, and a limited natural supply of oxygen whieh aetivates the organisms to deeompose the organie eonstituents. Initially in the biolysis of sewage deposited in the septie tank, urea, ammonia, and other produets of the digestive putrefaetive deeomposition are partially oxidized so as to eonsume the limited amount of oxygen initially present in the raw sewage. Consequently, further deeomposition of the sewage is by the anaerobie proeess. Continued putrefaetion ¦ oeeurs under the anaerobie eonditions 90 that the proteins are broken down to form urea, ammonia, fowl-smelling mereeptans sueh as hydrogen sulfide and fatty and aeromatie aeids.
.' . ' .
,;
, . , ..
f : - 2 -~ ~.. . . . . r : .:

-Carbohydrates are broken down into their original f~tty acid, water, carbon dioxide, hydrogen, methsne and other substances. Fats and soaps are affected similarly to the hydrocarbon and are broken down to form the original acids of their constituency as well as carbon dioxide, hydrogen, methane and the like, Stable nitrides and nitrates are produced as the final product of the anaerobic decomposition process, One substantial disadvantage of anaerobic sewage treatment in septic tanks is that there is an eventual accumulation of solid materials in the tank which must be periodically removed in order to avoid clogging of the drain field and consequent discharge of raw sewage in the area of the tank. Additionally, the efficiency of a septic tank is largely dependent upon the soil conditions in which the drain field is located since the percolation of the soil is determinative of the size of the drain fleld and its consequent capacity for receiving and disposing of llquid effluent. In some areas, it is impossible to employ septic tanks due to the poor percola-tion characteristics of the soil.
The deficiencies of anaerobic process septic tanks have resulted in a substantial movement toward the usage of aerobic sewage treatment sys~ems which also employ a receiving tank and a drain field but which additionally employ means for supplying oxygen to the sewage during its entlre treatment process to provide a more complete decomposition than is normally obtainable ln an anaerobic system. While the nerobic sewage treatment mb/~C~
. , . . . . i : .

- . . : ., . :

-~ 106Z381 unlts that are commerclally available have provlded substantlal advantages over the older anaerobic systems, they have suffered from a number of deficiencies from the standpoint of cost of manufacture, operation and maintenance which have slowed their acceptance as a substitute for the older anaerobic systems.
One of the more common problems with prior known commercial aerobic sewage treatment systems is that they fail to adequately dissipate the solid materials in the sewage and such materials consequently are discharged from the tank without full treatment. The discharge of solid materials into the drain field is highly undesirable since it can result in a blockage of the drain field within a relatively short time, In an effort to preclude the discharge of solid materials, some units have employed filters upstream of the outlet of the drain field. However, this approach has not proven to be satisfactory since the filters soon become clogged and must be replaced in order to remain effective.
Various other expedients have been employed in the prior known aerobic sewage treatment units such as aerators in the bottom of the main receiving tank, mechanical agitation devices, macerators and the like. Frequently, devices of the foregoing type have been overly complex and consequently prone to hlgh expenses of initial manufacture as well as of maintenance, Other problems with prior known systems include failure to obtain optimum oxygenation in a rapid manner which necessltates the employment of a larger maln tank than would be necessary lf lncreased rates of oxygenation coult be effected.

~b~ 4 -, . . . .. .

.

.
.. . . . .. -.: . . .. . . : .:. . . .

SUM~ARY OF ~HE I~vENTlor~
_ In order to avoid the above-described problems and to provide an improved treating method and apparatus, it has been discovered that the contaminated liquid should be sub-jected to a micro-liquefaction process in the presence of an oxygen-containing gas. This is accomplished by causing the contaminated liquid, under conditions of hydraulic turbulence, to flow tangentially across a knife edge whereby great shear forces act on the floc particles to micro-liquefy the floc.
An oxygen-containing gas injected at the knife edge optimizes oxygen transfer and, thus, aerobic treatment of the contaminated liquid. The invention includes apparatus for accomplishing micro-liquefaction in the presence of an oxygen-containing gas of contaminated liquids and sludRes contained in prior art septic tanks or other collection vessles.
Specifically, the present invention is used in a septic tank system for collecting ant treating contaminated liquids such as domestic sewage and relates to an improvement which comprises in combination: means for simultaneously withdrawing a portion of the contaminated liquid from the tank and reducing the size of floc particles contained therein;
means for introducing the contaminated liquid into an elongated generally cylindrical treatment vessel, the vessel containing a tangential inlet on one end and a tangential outlet on the other end to cause the liquid to circulate around the circum-ference of the vessel and along its axis, thus creating hydraulic turbulence in the fluid; the vessel having therein surface means to contact and reduce the floc particles in size by mechan-ical shear forces; and means to introduce an oxygen-containing gas into the liquid in the vessel; whereby the floc particles mb/~ ~ 5 ~

'- - , :- , . : - . . ,. -: .

.. : . . - . : : . ,.. , ..... - . . ..... - . ~ -: . .
,.. . :. . ~. , .. ' ., . ' .:"' ' ' ' -. ':"."' . ' ' . ' ' : '.'.:': : ' ' : . :: . . ~ . : .: ,... . . : . -.:. . - : - .-. - ~ . ' . ' :
. .

are subjected to optimum size reduction and optimum transfer of oxygen to maximize aerobic treatment of the contaminated liq~id.
The invention also relates to an aerobic sewage treatment system comprising in combination: a main sewage collection tank having a raw sewage inlet and an effluent discharge outlet;
a closed cylindrical treatment vessel for treating the sewage by micro-liquefaction of floc particles contained in the sewage;
the treatment vessel having a tangential sewage inlet at one end thereof and a tangential outlet at the opposite end thereof;
a baffle disposed axially within the vessel, the baffle present-ing at least one edge to contact and reduce the floc particles in size by mechanical shear forces; means to introduce an oxygen-containing gas into the vessel below the baffle so that the baffle acts to distribute the oxygen-containing gas throughout the vessel; means for conducting sewage deposited in the main collection tank to the inlet of the vessel, the conducting means including a conduit between the vessel inlet and a centrifugal pump disposed in the sewage in the main tank, the pump including a housing and an impeller in the housing, the impeller having blades with sharp edge portlons to contact and reduce the size of the floc particles before entering the vessel; whereby the pump forces the sewage through the vessel and induces hydraulic turbulence in the fluid in the vessel so that the floc particles .
in the liquid are further reduced in size by contacting the baffle as the liquid flows through the vessel and the oxygen-containing gas is introduced into the liquid to effect maximum aerobic treatment of the contaminated liquid.

mb/'~ 6 -.. ,i~
. . . .... ~ .. . . . ,, ... . .. ~ - - . ... ...
. . . . . -.. ... .
. . .. . - . . . . .. -.. . ...
.
. .. .. . . . . .. . . . .
.~ .. ,. .. .
.. . . . ... . ..
.' ' , .. 4 .
'' ', "' " ', ' ~ '' ' '' ~

One embodiment of the invention is achieved through provision of an aerobic sewage treatment system including a main sewage collection tank having a sewage inlet and an effluent discharge opening as well as gas venting means. A closed treatment vessel (micro-liquefaction chamber) of cylindrical configuration is positioned externally of the main sewage collection tank for receiving sewage from the tank by operation of a pump positioned at a lower level near the bottom of the main tank. The pump comprises a hollow S-shaped centrifugal impeller, having sharp outer edges for providing a first size reduction of the solid (floc) particles fed to the pump by an axial inflow line extending downwardly to a bottom end ter-mination adjacent to the lowermost portions of the main tank.
A hollow drive shaft has an upper opening above the liquid level in the tank into which air flows and a discharge opening into the interior of the impeller so that air flows downwardly ; into the pump for mixing with the sewage when the pump is operated. The solids, dissolved gases and undissolved gases flowing from the pump are carried upwardly and forceably in~ected into the inlet of the treatment vessel (micro-liquefaction chamber).
The inlet of the treatment vessel or micro-liquefaction chamber is oriented tangentially with respect to the cylindrical chamber so that material in~ected into the chamber creates a f vortex of rapidly swirling liquid and solids. The outlet of the micro-liquefaction chamber is also oriented tangentially ~ with respect to the cylindrical chamber in the same manner as 4 the inflow opening so as to permit the discharge of material from the compartment in a manner requiring no direction change mb/~ ~ - 6a -~.w~

' . ' .'. . .,', '. ' : ''~' . . . - ., . , ... : .: , , . .. : .:

,:

of consequence such as would decrease the vorticity of the material within the chamber. Additionally, an inverted angle member having sharp edged sùrfaces extends axially within the treatment chamber and air is injected beneath the angle member.
The swirling vortex of liquid containing solid (floc) particles is under conditions of hydraulic turbulence and the floc parti-cles contacting the angle member are subjected to great shear forces so that they are micro-liquefied and provide optimum m ximum molecular transfer of the oxygen in the air into solution with the liquid.
Therefore, it is the primary object of this invention to provide a new and improved sewage treatment system.
It is another object of the invention for the provision of a new and improved aerobic sewage treatment means.
It is yet another object of the subject invention for the provision of a new and improved aerobic sewage treatment system capable of micro-liquefaction and the resulting rapid molecular transfer of oxygen and nutrients into the waste to obtain optimum aerobic process.
It is still another ob~ect of the invention to provide a new and i~proved sludge-free sewage treatment system.
It is yet a further ob~ect of the present invention to provide a new and improved primary liquefaction pump fos initially reducing the size of the solids and microorganisms and intro-ducing an oxygen-bearing gas into the contaminated liquid.
It is still a further ob~ect of the invention to provide a new andimproved aerobic sewage treatment method and apparatus that can be utilized in con~unction with any shape tank as a biological reactor.

~t~ 6~
~ #,..~
.: " ' ' . ' ' ' ' . ~ ' , '' ~
. ' : , '' : . . : - ' .
,........ . . ' ' '' . . .' ~ '''' ,, ' ' :
.. ' ' ', ' ~ ' '' ,, .. . .
, - - ' ' ' ' ' :
- ' . : , ' ' '' ' ~
~, .

1. -_ I ~ ` 106Z381 A better understanding of the manner in which the preferred embodiment is constructed and operated will be achieved when the I following detailed description is considered in conjunction with ¦ the appended drawings in which:
¦ FIGURE 1 is a partial perspective of the preferred embodi-ment mounted in a conventional septic tank with portions removed-I for purpo~es of illustration clarity;
¦ FIGURE 2 is a sectional view taken along lines 2-2 of Fig-¦ ure l;
¦ FIGURE 3 is a sectional view taken along lines 3-3 of Figure 2;
FIGURE 4 is a top plan view; and FIGURE 5 is a sectional view taken along lines 5-S of I Figure 4 and including an optional feature.
I Attention is initially invited to Figure 1 of the drawings j which illustrates the preferred embodiment of the invention, ¦ generally designated 8, as mounted on a conventional main sewage ¦ coi.lection tank 10 which would normally be buried in the ground i I an area as conveniently close to the facilities to be served by ¦ the unit as practical. Main tank 10 comprises a ~ottom wall 12, a top wall 13, an end wall lS through which an inlet pipe 16 ex-¦ tends with the end of the inlet pipe being in the form of a sani-¦ tary tee member, an opposes end wall 17 in which an outlet 18 al-¦ so includes a front wall (not shown) and a rear wall 19. The in- . ..
¦ terior of main tank 10 defined a sewage digestion chamber 20 with .
¦ the solids gravitating downwardly to the bottom of the chamber a~
¦ illustrated in Figure 1. When the level of the liquid in the cham ¦ ber 20 reaches the same height as the outlet 18, liquid effluent . ¦ will be discharged to a drainage field to eventually percolate ~0 I downwardly into the ground. A vent pipe 22 ig provided ~n the top .
~ ' ' ' ' , - ` ' ' ~ ' ' ~ ' -` 1062381 13 of the maln tank 10 for permittlng the escape of gases from the chamber 20.
The preferred embodiment 8 of the sub~ect invention is positioned over an opening 24 in the top 13 of the main tank 10 and includes a base plate 26 resting on the upper surface of the top 13 and completely overlying and covering the opening 24.
An intensified micro-liquefaction chamber 28 consisting of a horizontal cylindrical tank portion 30 having its ends closed by end plates 32 and 34 is mounted on the base plate 26. Tank 30 is supported by the lower surfaces of end plates 32 and 34 which rest on the base plate 26 and are normally welded or otherwise secured thereto. A tangential inflow conduit 36 is connected to the cylindrical tank portion 30 adjacent to end wall 32 as best illustrated in Figures 1 and 2. Additionally, a tangential outflow conduit 38 is connected to the opposite end of the cylindrical tank portion 30 adjacent to end plate 34. The inflow and outflow conduits 36 and 38 are oriented to provide a vortex flow between the inlet and outlet as illustrated by the arrows in Figure 1 for the purpose of achieving optimum micro-liquefaction and the resulting molecular transfer of oxygen and nutrients of the materials passing through the cylindrical tank portion 30. A source of compressed air 40 from compressor 41 i~
connected to a fitting 42 in the end plate 32 positioned coaxlally with respect to the cyllndrical tank portion 30 beneath a baffle 44 extending the length of the cylindrical tsnk portion 30. Baffle 44 comprl8e8 an lnverted angle . . mb/~ - 8 - `

,, .. ~- . : . . . . ............................. . ~ .

, . .
,: , . . - , `` ~062381 member having shArp edges 46 as shown in Figure 3 with the lnlet fittlng 42 belng positioned with respect to the baffle as best lllustrated ln Figure 5, The swlrllng vortex of materlal on the interior of the cylindrical portlon 30 engages the sharp edges 46 to provide intensified micro-liquefaction of the nutrients and molecular transfer of the oxygen injected via the fitting 42 with the pressure in the tank being at approximately 3.5 pounds per square inch. The proximity between the sharp edges 46 of the baffle 44 and the inside wall of tank portion 30 is such that large ob~ects are thrown back into sharp edges 46 of the baffle many times before exiting out of tank portion 30 through outflow conduit 38.
A vertically oriented pump support sleeve 48 extends downwardly from the base plate 26 to provide support for a unique micro-liquefaction centrifugal pump 50 including a casing 52 from which an axial inflow conduit 54 extends downwardly to a lower end termination 56 as best illustrated in Figure 1. Pump support sleeve 48 encloses a hollow :
tubular axial pump drive shaft 58 supported in roller bearings and having its upper end drivingly connected to an electric motor 60 which also drives the air compressor 41.
A pump impeller 62 is fixedly connected to the lower end of the hollow drive shaft 58 and includes a top plate 63 and an S-shaped downwardly extending hollow lmpeller blade 64 best illustrated in Figure 3. And internal passageway 65 in the S-shaped lmpeller blade 64 ls ln communication with the lower end of the hollow tubular drive shaft 58 and the outer end of the passa~eway 65 is , -~ mb/l~

, .. .. .. . - ., . - . . ,- ~ . . .
, ,, . , ,. f . . . .:
.: . .

~ 1062381 de1ned by a sharp edge 66 beflt ill.ustrated in Figure 3.
And air inflow opening 67 i8 provided in the support sleeve 48 and a second opening 67 is provided in the upper end of the hollow tubular drive shaft 58.
Impeller 62 is driven by the motor 60 in the direction of the large arrow in Figure 3 so that the rotation of the impeller draws air downwardly through the openings 67 and 67' into the passageway 65 from which the air exits past the sharp edges 66. The movement of the impeller and the inflow of air provides an extreme amount of hydraulic turbulance and micro-liquefaction of the nutrients and molecular transer of the oxygen ingested into the pump housing with the input flow being upwardly through inflow conduit 54 and then discharging outwardly through the outlet of the pump casing to an ~ outlet line 72. It will be evident that the trailing edges 66 provide micro-liquefaction of the solid particles flowing through the pump and the inflow of air through the impellor provides for optimum molecular transfer of the oxygen into solution with the liquid. The pump is designed to pass 30 GPM and ingest 2.9CFM of air at the same time which is evidenced by an extreme pulsating discharge totally unique for a centifugal type pump.
The upper end of the outlet line 72 is connected to the tangential inflow conduit 36 of tank 30 a~d the oxygenated discharge conduit 74 is connected to the outflow conduit 38 for disch.arging oxygenated micro-liquefied sewage back into the main tank lO. The lower end of conduit 74 can be positioned beneath the surface mb/~c . ~ - 10 -i, . . .
.. ~ .

. ~ . :,, ~ :

-~` 1062381 of the liquld ln the tank lf deslred~
In the operation of the embodiment, the electric motor 60 i9 actuated to drive the pump 50 and the compressor 41. Operation of the pump serves to pump mlcro-llquefled sewage, dlssolved and undlssolved gases upwardly through the intensified micro-liquefaction chamber 28 wlth alr belng lnjected into the chamber by means 40, 42 in an obvious manner as discussed previously.
The material passing through the cylindrical tank 30 is given a whirling vortex motion due to the orientation of the tangential lnlet 36 and the tangentlal outlet 38, It is of particular importance that the tangential outlet 38 is oriented so as to enhance the vortex flow through the cyllndrlcal tank portion 30 to the fullest extent possible. The vortex of the material on the interior of the tank is rapidly moving past the sharp edges 46 of the baff]e 44 to provide optimum mixlng efficiency of the liquid and air on the tank interior, Additionally the movement of solid materials past and against the sharp edges 46 also provides further micro-liquefaction of these materials.

mb/ ~ 108 -- : .,; ~ ' :
,. - . :
... , , . , , .:
'; .; , ~

- - ~
-~ ~ l 106Z381 - !

Figure 5 illustrates an optional feature comprising an air injection line 70 for providing additional compressed air to the inflow conduit 54.
The flow of the liquid and solid materials across the knife edges results in great shear forces and turbulence in the materials which mechanically and continually reduces the eddy film thickness and flock particle diameter of the micro-organisms present in the sewage. The production of increasingly thinner eddy film thickness and smaller particle diameters increases the transfer rate of oxygen and nutrients into the solution providing an optimum maximum dissolving of oxygen and nutrients into the sewage. The sewage, dissolved oxygen and non-dissolved gasses, primarily consisting of nitrogen, are then discharged from the intensified micro-liauefaction chamber by the conduit 74. The oxygenated sewage is conseguently returned to the main tank 10 in which the dis~olved gas and nutrients are mixed with sewage in the digestion chamber 20 to undergo aerobic treatment. Undis-solved gasæe~ are vented by the vent pipe 22 into the atmosphere.
Continuous inflow of raw sewage into the tan~ results in an even-tual outflow of treated sewage from the outlet 18 in an obvlousmanner.
Maximum biolysis of the sewage occurs by virtue of several construction features employed in both embodiments of the inven-tion. Specifically, the pre-mixing of the sewage with air in tho unique micro-liguefaction pump 50' serve~ to enhance the cutting operation of the impeller on solid particles as well as to oxygen-ate the sewage. The whirling vortex of material in the cylindsi-cal tank 30 past the sharp edges 46 of baffle 44 provides addi-tional particle size reduction and oxygenation. Moreover, it ha~
been found that the effluent discharged from the outlet 18 con-tains sufflcient oxygen to continuo tho oxygenation process 1n the drain fiold. ' ..
' '~ ' . " ' ,, .
. .
: . :
: . - : .
- .. - , . . . . .
. ' :: ' ~ ' . ' ..

. , ~ : :

~ - --~ ~ . -~062381 .
In the biolysis of sewage in septic systems as previouslydiscussed, the digestive process is conducted only for a short _ period of time under aerobic conditions until the supply of natural oxygen is consumed. After the natural oxygen has been S consumed, the treatment process becomes an anaerobic process which eventually results in a low biochemical oxygen demand reduction (~.O.D.~ in the order of 30 percent. The superiority of the subject invention over such prior known systems is evidenced by the fact that the biological oxygen demand of the effluent from the subject invention is of the order of 9S
percent and is both odorless and clear. -It is contemplated that the subject invention can bemanufactured and employed as a new installation or that it can be installed on an existing septic tank for the purpose of conver-ting to an aerobic sewage treatment process. The system providessubstantial advantages due to the high guality of the effluent-and does not require as substantial a drain field as is necessar with other type systems.
It i~ understood that the subject invention is susceptible to numerous modifications and adaptions that will be obvious to those of skill in the art; therefore, the spirit and scope of the invention is to be limited solely in light of the appended icl~

~, I . '' I
~,.1 . I , lz_ ~ .
~, . : - .......... - ,.. : :' ,''~ ~ ' ::-': , :' -. .: . . .
~. - ~ - .. .

Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a septic tank system for collecting and treating contaminated liquids such as domestic sewage, the improvement which comprises in combination:
means for simultaneously withdrawing a portion of the contaminated liquid from said tank and reducing the size of floc particles contained therein;
means for introducing the contaminated liquid into an elongated generally cylindrical treatment vessel, said vessel containing a tangential inlet on one end and a tangential outlet on the other end to cause the liquid to circulate around the circumference of said vessel and along its axis, thus creating hydraulic turbulence in said fluid;
said vessel having therein surface means to contact and reduce said floc particles in size by mechanical shear forces; and means to introduce an oxygen-containing gas into said liquid in said vessel; whereby said floc particles are subjected to optimum size reduction and optimum transfer of oxygen to maximize aerobic treatment of the contaminated liquid.

2. A system according to claim 1 including means to return said treated liquid to said septic tank.

3. A system according to claim 1 wherein the means for contacting said floc particles includes a knife edge disposed longitudinally in said treatment vessel.

4. A system according to claim 1 wherein said means for introducing an oxygen-containing gas into said vessel is disposed adjacent said inlet.

5. A system according to claim 1 wherein said means for withdrawing said liquid from said septic tank includes a centrifugal pump including a housing and an impeller in said housing, said impeller having sharpened leading and trailing edges to reduce floc particles on contact by mechanical shear forces.

6. A system according to claim 1 wherein said means to introduce an oxygen-containing gas into said liquid in said treatment vessel includes an air compressor and a conduit between the discharge of said compressor and said vessel.

7. A system according to claim 1 wherein said means to introduce an oxygen-containing gas into said liquid includes a baffle extending substantially the length of said cylinder with an oxygen-containing gas inlet disposed underneath said baffle to conduct said gas along the length of said baffle.

8. A system according to claim 2 including means to direct a portion of the treated liquid to an outlet baffle of said septic tank.

9. A system according to claim 7 wherein said baffle is an angle member having an inverted V-shaped cross section with the outer edges of said member being sharpened.

10. An aerobic sewage treatment system comprising in combination:
a main sewage collection tank having a raw sewage inlet and an effluent discharge outlet;
a closed cylindrical treatment vessel for treating said sewage by micro-liquefaction of floc particles contained in said sewage;

...... claim 10 cont'd.

said treatment vessel having a tangential sewage inlet at one end thereof and a tangential outlet at the opposite end thereof;
a baffle disposed axially within said vessel, said baffle presenting at least one edge to contact and reduce said floc particles in size by mechanical shear forces;
means to introduce an oxygen-containing gas into said vessel below said baffle so that said baffle acts to distribute said oxygen-containing gas throughout said vessel;
means for conducting sewage deposited in said main collection tank to said inlet of said vessel, said conducting means including a conduit between said vessel inlet and a centrifugal pump disposed in said sewage in said main tank, said pump including a housing and an impeller in said housing, said impeller having blades with sharp edge portions to contact and reduce the size of said floc particles before entering said vessel;
whereby said pump forces said sewage through said vessel and induces hydraulic turbulence in said fluid in said vessel so that the floc particles in said liquid are further reduced in size by contacting said baffle as said liquid flows through said vessel and said oxygen-containing gas is introduced into said liquid to effect maximum aerobic treatment of said contaminated liquid.

11. A system according to claim 10 including means to discharge effluent from the treatment vessel into said main sewage collection tank above the level of liquid contained therein.

12. A system according to claim 10 wherein said baffle comprises an angle member having an inverted V-shaped ....... claim 12 cont'd.

cross section with sharp outer edge portions.

13. A system according to claim 10 including means to divert a portion of the effluent from said treatment vessel to the effluent discharge outlet of the main sewage collection tank.

14. An aerobic sewage treatment apparatus adapted for use with a sewage collection tank having a top opening, a raw sewage inlet and an effluent discharge outlet, said apparatus comprising:
support means supportably positionable on said tank overlying said top opening and including a downwardly extending vertical support extendable downwardly through said top opening to have its lower extent below said discharge outlet;
a closed cylindrical intensified micro-liquefaction tank positioned on said support means, said closed cylindrical intensified micro-liquefaction tank having a tangential sewage inlet at one end of said cylindrical tank;
a centrifugal pump mounted on the lower extent of said vertical support so that said pump is positionable below the surface of sewage in said collection tank, wherein said centrifugal pump includes a hollow impeller blade having an internal passageway extending along its entire length, a hollow driveshaft connected at its lower end to said impeller blade and having an internal passageway in communication with a central portion of an S-shaped hollow impeller blade, said impeller blade is provided with sharp trailing edge portions adjacent the ends of said hollow passageway extending through said hollow impeller blade;

...... claim 14 cont'd.

means for injecting a gas including oxygen under pressure into said cylindrical intensified micro-liquefaction tank, said means for injecting a gas including oxygen into said cylindrical intensified micro-liquefaction tank includes an air compressor and conduit means connected between said air compressor and an axial portion of said cylindrical intensified micro-liquefaction tank;
an axially positioned baffle means disposed within said cylindrical intensified micro-liquefaction tank for guiding air injected into said cylindrical intensified micro-liquefaction tank along the axis of said cylindrical intensified micro-liquefaction tank for mixing with a vortex of liquid and solid particles passing through said cylindrical intensified micro-liquefaction tank; and means for conducting undissolved gases, dissolved gases and sewage from a tangential outlet in said cylindrical intensified micro-liquefaction tank to discharge below said support means to enable return of same to a collection tank.

15. The aerobic sewage treatment invention of claim 14 including means for conducting a portion of output from the outlet of said micro-liquefaction tank to the effluent discharge outlet of said sewage tank.

16. The aerobic sewage treatment invention of claim 14 wherein said baffle means for guiding said air injected into said cylindrical intensified micro-liquefaction tank comprises an angle member having an inverted V-shaped cross-sectional configuration with sharp outer edge portions.

17. A method of treating a contaminated liquid such as domestic sewage normally discharged into a septic tank comprising the steps of:

...... claim 17 cont'd.

continuously withdrawing a portion of the contaminated liquid from the septic tank;
injecting the withdrawn liquid into a closed treating vessel having therein surface means to contact floc particles contained in the liquid;
causing said liquid to flow tangentially through said vessel under conditions of hydraulic turbulence so that said floc particles are subjected to shear forces by moving across said contacting means in said vessel; and simultaneously injecting an oxygen-containing gas into said vessel; whereby said portion of the contaminated liquid in said vessel is given a maximum aerobic treatment of micro-liquefaction of the floc particles in the contaminated liquid and returning said treated portion of said contaminated liquid to said septic tank.

18. A process according to claim 17 wherein a portion of the contaminated liquid is continuously withdrawn from the septic tank and the micro-liquefied treated liquid is returned to the tank above the level of the contaminated liquid.

19. A method according to claim 17 wherein as said contaminated liquid is withdrawn from the septic tank, the floc particles contained therein are subjected to a first size reduction prior to being injected into said treating vessel.

20. A method according to claim 18 wherein a portion of the micro-liquefied treated liquid is returned to the discharge outlet of the septic tank.