CA1106129A - Integrated sewage treatment system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An on-site system in which means for treating domestic sewage generated within a building located thereon are totally integrated with means for modifying space temperatures and for heating water for sanitary and other purposes therein to form a matrix of interrelated and interdependent functions acting together to deliver only non-polluting products to the environment and to achieve maximal energy conserva-tion.

Description

OBJECTIVES OF THE INVENTION

A principal objective of the invention is to provide communal protection against health hazard and aesthetically offensive emanations, independent of soil biology and the soil mechanics pertaining on the site which might originate in a building constructed and occupied thereon.
A further objective of the inventio~ is to enhance the institutional reliability of the communal protection provided by utilizing only means which lend themselves to total automation and avoiding all techniques requiring that chemical reactants be added to the se~:age trëat~ent process.

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. ' , Another important objective of the invention is to intrinsically bias the sewage treatment function in favor of being maintained in good working order by reciprocally integrating it with other functions normally construed as being essential within a building for the physical comfort and convenience of the occupants.
Underlying this objective of "intrinsic bias" is a principle in the public regulation of on-site sewage treatment and dispos~ that has come to be known in the regulatory community as ffinstitutional reliability." That principle is not to be confused with the usual and ordinary ideas of equipment or process reliability which focus on considerations intrinsic to the equipment or process and do not impel user contributions to their reliability. Certainly the ordinary and usual ideas of reliability are relevant to on-site sewage treatment and disposal, but institutional reliability goes well beyond this to address an unusual situation in which the failures, of any of a multitude of individual users for any of a myriad of reasons, to make the contributions required of them, in the form of unremitting attention to the integrity and continuity of system operations, might bring down penalties, not alone on themselves but on the public-at-large as well, in the form of radiating epidemic disease and ecological damage, the sources of which it could be virtually impossible to pin-point and correct before substantial public injury had been experienced.

It is fundamental to the idea of intrinsic bias, and correspondingly to the principle of institutional reliability that given the economic, social, and career pressures and distructions of daily family life and the variations, and combinations of variations, that exist in society .

11~612g with respect to intelligence, education, and personality~ an individual user may more or less frequently and persistently perceive his personal interest as diverging from the public interest with regard to his on-site sewage treatment and disposal system and the undeviating maintenance of the integrity of its processes. In a "stand-alone" system, such a percei~ed divergence could lead to the failure to provide necessary consumable supplies and to the neglect of maintenance and repairs and, hence, the public penalties cited above. Moreover, with many millions of systems in use, sufficiently close public surveillance to prevent their occurrence could not be accomplished.
It is also fundamental to the concept of intrinsic bias that virtually everyone, even the most eccentric or recalcitrant, wants a warm home in cold weather, a cool one in hot weather, and/or hot water for his personal sanitary needs and that he is unlikely to forego a~y of them willingly, if he can possibly help it. Whether or not it would be possible by the force of public power or persuasion to prevent or eliminate a sense of divergence between the individual user's interest and the public's interest in this matter of on-site sewage treatment, the inextricable integration of all these household functions will accomplish the same purpose by bringing about a convergence between the public interest about which the user may continue to care very little and his own interest about which he cares a great deal, because the former will be served as a by-product of the latter.

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Another objective of the invention is to use the energy derivable from the combustible components of raw human excrement and from other combustible organic wastes normally associated with the processes of human living to produce a net reduc~ion in the aggregate system demand for externally supplied commercial fuels or other sources of energy.
A further objective of the invention is to provide a system that is adaptable and convertible from time to time to the use of virtually any liquid solid or gaseous fuel, or the use of electrical power, as an acceptable source of externally supplied energy for system processes in order to ensure maximal operating economy as the prices of fuels and electrical power may fluctuate from time to time and from place to place.
Another objective of the invention is to provide for on-site treatment of human excrement wherein the energy demand for physical treatment of the liquid component thereof is recipro-cally integrated with the energy demands of other functions normally existing and consistently used in the structure located on the site to the end that the aggregate system energy demand is reduced by multi-purpose employment.

~1~6~29 Another objective of this invention is to p~ovide a waste disposal system which can be used at sites not served by sewer and which converts building wastes into non~polluting gases and vapors for delivery to the atmosphere and relatively harmless water for delivery to the ground.
A still further objective of this invention is to provide a waste disposal system in which pressurized liquid-phase thermal sterilization of the waste takes place, resulting in'a net decrease of the energy required to operate the system.

BACKGROUND OF THE INVENTION
~ As population throughout the world increases, the - disposition of human waste materials becomes an increasingly vexing problem. In many instances, federal, local and state agencies have resorted to stringent restrictions on the methods employed to dispose of such waste.
In less densely populated areas, where the per capita costs of sewage collection and treatment systems are prohibitive, on-site septic tank systems have represented the preferred method of human waste disposal for many years. Unfortunately, septic systems require precise soil characteristics for satisfactory performance. If soil percolation rates are too high, pathogenic and other contaminants can be carried into the water table and . thereby present a public health hazard. If percolation rates are too low, septic tank effluents can bubble to the surface and present many undesirable consequences. I.here the ~ater table is high or is seasonably or variably high, there have been cases where septic tanks have floated out of ground in res?onse to seasonal variations.

~1~61~9 For the foregoing and other reasons, public agencies in growing numbe~s are prohibiting the use of septic tank systems unless rigid sub-surface conditions can be demonstrated to exist at the proposed building site. Because of these standards, there are many otherwise desirable building sites which cannot be utilized for construction unless public sewage systems are installed. This is an eventuality which may not occur. This results in otherwise desirable property lying idle in the face of tremendous needs for more housing and other building construction. These needs are oftentimes relieved by the selection of less desirable properties having better soil conditions.

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ADVANTAGES OF THE INVENTION

The system of this invention represents the concept of combining into a single automated system a sewerage treatment function and many building service functions normally accom-plished by separate systems. The system also extracts energy from sewage solids and organic wastes by incineration and thereby produces a net reduction in the aggregate fuel demand for these functions. Preferably, the system employs pressurized, liquid-phase thermal sterilization to treat the liquid sewage.

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While accomplishing the above benefits, the system of this invention presents only non-polluting and non-noxious gases to the atmosphere. The water presented to the soil is of a quality at least equal to that delivered by modern tertiary sewage treatment plants.

~ loreover, as previously noted, the syster,l incorpora.es an intrinsic bias which virtually guarantees maintenance of the system in a manner calculated to serve the public's good as well as the owner's private good.
lo These and other advantages of the invention will become more apparent to those skilled in the art by reference to the following detailed description when viewed in light of the single accompanying drawing disclosing a schematic of the system.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRE~ EMBODIMENT

Illustrated in Figure 1 is a system of vessels, filters, pumps, heat exchangers, valves, conduits and controls that are combined to accept raw sewage and organic garbage from a residence or other source and to process it in an improved manner. The wastes are physically separated into essentially solid-free liquids and wet solids. The wet solids are mixed with a supplementary fuel component and the mixture is incinerated. (The wastes and -the fuel component are both fuels. Hereinafter, the mixture will be called the fuel slurry.) The liberated energy of combustion is used to process the solid-free liquid so that all pathogenic organisms are ' destroyed by pressurized liquid-phase thermal sterilization. The energy is then taken from the hot effluent by means of heat exchangers and subsequently utilized for the heating or cooling of enclosed space and the heating of sanitary hot water. Rela-'~

1~'6129 tively cool, odor-free, sterile and essentially solid-free effluent is delivered to the soil for absorption.
Referring now to the schematic wherein like elements are referred to by like numerals, the system as a whole is indicated by the numeral 10. The normal household appliances that process residential wastes are labeled as such in the drawing and are indicated as a group by the numeral 12. Chemical wastes and the sediment from the grease trap are separately collected into conduit 14.
A receiver vessel 20 is provided to accept the liquid and solid organic wastes from facilities 12. This receiver vessel is sized to permit storage during peak periods. The flow capacity of the system is rated to an average flow on a sixteen hour cycle of activity followed to the end of the day by eight hours of relative quiescence.
Raw wastes from vessel 20 are delivered through a normally open valve 30 to a filter 32. Filter 32 is of a design capable of filtering solids down to a size of less than 500 microns which is smaller than the largest sizes normally dis-charged in the effluent of a modern sewage treatment plant. The filtered liquid passes through a normally open valve 34 to an effluent collector 36. In the outlet conduit 38 from the filter 32 there is disposed a valve 40. Valve 40 is normally closed and will hold filtered solids in the filter 32 until activated.
On a pre-arranged signal, valve 30, in the conduit bettJeen the receiver 20 and the filter 32, closes and the valve 40 612~

opens. The solids, together with a measured amount of water, pass to a slurry homogeniæer 42. At this same time, a measured amount of fuel is introduced into homogenizer 42 by a fuel pump or delivery mechanism 44. The solids and liquid in homogenizer 42 are homogenized by mechanical agitation.
Upon receiving a second pre-arranged signal, this homogenized fuel and solid slurry is introduced into conduit 46 leading to burner 50. A valve 48 is disposed in conduit 46. The atmosphere in burner 50 is electrically and thermostatically controlled at a temperature level above the flash temperature of the slurry and is continuously supplied with ambient air by means of a gas duct system 47 which is driven by a centrifugal stack blower 54.
The gases developed during combustion in the burner 50 pass to a scrubber 52 where unreacted organic gases are completely -~ oxidized to water and carbon dioxide. This is accomplished with the assistance of contact with an appropriate catalyst at an appropriate temperature. Inorganic gases, typically sulphur gases, are removed from the gas stream in the scrubber 52 by reaction with suitable chemical getters. The burner 50 and scrubber 52 can be of the type more fully described in the United States patents to Greenberg No. 3,642,583 and the United States patent to Greenberg, et al No. 3,647,358.

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_ g _ 11~6129 'Reduced to its fundamentals, the above described burning and scrubbing represents an oxidation process by which the individual elements making up the organic compounds are reacted with oxygen from the combustion-air supply to form inorganic end-products. That process is known in the trade as "mineralization," regardless of the means by which it is accomplished. In its essentials, the above described combustion and scrubbing parallels, more or less exactly, the effect that might otherwise be accomplished by aerobic bacterial metabolism.
That is, the combined effect of filter 32, homogenizer 42, burner 50, and scrubber 52 is to mineralize the organic component of the sewage to relatively innocuous inorganic end products.
-~ After scrubbing, the gases pass to a pressurized sterilizer 56 and thence to the aforementioned effluent collector 36. The two segments of gas duct 51 which transit through pressurized sterilizer 56 and effluent collector 36 are both gas-to-liquid heat exchangers. The gas therefrom passes to the stack 53 for discharge to the atmosphere.

; As the sewage filtrate is accumulated in collector 36, evolution of dissolved gases is promoted by the secondary cooling of the burner stack gases and a consequent rise in filtrate temperature. Ammonia, carbon dioxide, and organic gases are carried to the burner ;0, where the last-mentioned burns spontaneously in its supply air stream (see air conduit -segment 47), which stream has transited across the liquid surface in collec~or 36. The temperature in burner 50 is high enough to decompose the ammonia into nitrogen and hydrogen and to ignite the hydrogen, which burns to water vapor.
When the filtrate level in the collector 36 rises to a pre-determined level, a collector high level control 55 is activated. Through appropriate control circuitry, an effluent sterilization sequence is established wherein the normally closed valves 58 and 60 are opened and operation of the sterile effluen~
pump 64 is initiated. The contents of the pressurized effluent sterilizer 56 are pumped to a first stage storage vessel 59a displacing an equal volume of liquid to the second stage storage vessel 59~.
A sterilizer low level control 62 of the sterilizer 56 is actuated initiating a second~sequence wherein valves 58 and 60 are closed and the operation of pump 64 is terminated. The normally open valve 66 is closed and the normally closed valve 68 opens.
The closing of valve 66 takes the first-stage storage thermostat 84 off alert, and the events it normally triggers will not occur while valve 66 is closed. Operation of the pathogenic effluent pump 70 is initiated and valve 34 closes. I'hen the contents of the effluent collector 36 are com?letely pu~ped (via pum 70) to .
ilZ9 the pressurized effluent sterilizer 56, a collector low level control 72 is actuated and a third sequence step is initiated wherein valve 68 closes and operation of the pump 70 is terminated.
Valve 34 is opened to allow resumption of flow to the effluent collector 36. One of the effluent sterilizer thermostats 76 is energized to thereby open valve 48 allowing fuel slurry to enter the burner 50, where the fuel-laden slurry iynites spontaneously.
In due course, the effluent temperature in the effluent sterilizer 56 reaches a sterilization level, and a thermostat 78 is actuated. This starts a sterilization timer 79. It is known that maintaining sewage at 300 F. for a period in excess of twenty minutes destroys all living organisms in water suspension, and the thermostat 78 and the sterilization timer 79 are preferably set at those values. During the sterilization sequence, the sterilizer thermostat 76 closes down burner 50 but remains ready to operate the burner intermittently during a sterilization hold period.
It should be particularly noted that, since the sterilizer 56 is a pressurized vessel, or autoclave, temperatures in excess of the atmospheric-boiling temperature of water, such as the previously mentioned temperature of 300F., can be achieved without the sewage's undergoing a phase change. This fact results in the pressurized liquid-phase thermal sterilization of the se~age, which is substantially more energy efficient than unpressurized thermal sterilization of se~age wherein a great deal of energy is ~asted in converting the li~uid to vapor.

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It is possible that the fixed amount of fuel-slurry in the slurry homogenizer 42 will become depleted during th third sequence of steps. If there is a depletion, there wi~l be an interruptiOn in sterilizer heat-up or the sterilizati temperature "hold period" which could potentially invalidat the sterilization process, if it were to proceed on a fixed time cycle. The supplementary fuel supply 44, however, is initiated independently of the effluent system control circuitry by a homogenizer low level control 80. When this occurs, interlocks (not shown) between the fuel supply system contrOl ; circuitry and the effluent syst~m control circuitry takes the sterilizer thermostat 76 (which is put on line by the opening ~- of valve 90) off line, close valve 48 and re-set and hold the sterilization timer until completion of the supplementary fuel supply sequence. At that time, the effluent is brought bac~
to sterilization temperature and the timer re-started.
During sterilizer heat-up, hold and discharge sequenc~, the collector high level control 55 is held on alert to close valve 34 and prevent a rise in fluid level in the collector 36 above a predetermined point. It is also ready to initiate a new sterilizatbn sequence immediately upon completion of a previous one should this be indicated.
Vpon completion of the sterilization hold period, th-~timer initiates a fourth sequence wherin the valves 66, 58 .-n~3 60 are opened, pressurized sterilizer ~ is taken off operalin:

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alert, and operation of pump 64 is initiated to pump the contents of the pressurized effluent sterilizer 56 to the first stage storage vessel 59a ~ at the completion of which the sterilizer low level control 62 terminates the sterilization sequence. The effluent system control is then placed on stand-by alert.
The sterile effluent pumped to the vessel 59a forms the source of energy for heating a supply of sarlitary water.

The effluent is pumped continuously by the heat exchanger pump 86 through an instantaneous water heater 88 close-coupled to the first stage storage vessel 59a.
Should the effluent temperature fall below a selected point while no sterilization sequence is in progress, a storage re-heat sequence is initiated by the first stage storage vessel thermostat 84. The normally closed valves 90, 92, 94 are opened and the operation of the sterile effluent pump 64 is started. The effluent temperature being below the control point of the effluent sterilizer thermostat 76 (which is placed on alert as Part of the re-heat se~uence), burner opera-tion is initiated and circulation of first stage storage content is continued until thermostat 84 stops the sequence.

The second stage storage vessel 59b forms the source of energy for the enclosed-space heating function. This vessel receiveS its supply of energy from the high temperature effluent displaced from the first stage storaae vessel 59a. The temperature of the effluent in the second stage storage 59b is controlled 6~9 by the second stage storage thermostat 96 which is on alert at all times, whether or not the sterilization sequence is active. Upon demand from the second stage storage thermostat 96, normally closed valves 98 and 60 open and operation of pump 64 is initiated. circulation to first stage storage 59a and return therefrom by displacement continues, independent of any other system functions, until the second stage storage selected temperature is restored. Supply air for the burner 50 initially transits across the li~uid surface of the second stage storage 59b to insure removal of ammonia from the effluent prior to discharge.
Actuation of an enclosed-space thermostat 102 opens the normally closed valves 98 and 100 and initiates operation of pump 64. The pump continues to circulate heated effluent to the enclosed-space heat transfer system 104 until the enclosed-space thermostat setting is achieved or restored. This circu-lation is not interrupted by operation of any other system sequence.
~ or system start-up, valve 106 is opened manually and operation of the control system is initiated. All pre-viously described sterile effluent system sequences will be triggered and in due course all components thereof will be filled with appropriately heated water at which time overflow to ground will occur from second stage storage 59b indicating that manual valve 106 is to be manually closed.

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11~6~9 It should be noted that sterile effluent conduit circuitry is designed so that sterile effluent pump 64 can draw effluent through valves 58, 90, and 98 either individually or simultaneously in any combination and deliver through valves 60, 92, and 100 either individually or simultaneously, and the pumping capacity is sized accordingly.
In a general manner, while there has been disclosed as effective and efficient embodiment of the invention, it should be well understood that the invention is not limited to such an embodiment as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

Claims (39)

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

1. An integrated sewage treatment system comprising (a) first means for collecting domestic sewage composed of human excre-ment and other organic and inorganic wastes entrained in transport water, (b) second means for liquid-phase thermal-sterilization of said sewage, (c) third heat-transfer means for regeneratively utilizing the thermal energy contained in said sewage after sterilization to energize at least one other thermally-motivated function normally associated with human domestic life, and (d) fourth means for disposing of said sewage after its thermal energy has been utilized and depleted.

2. The system of Claim 1., wherein said third heat-transfer means energize dwelling-space temperature-modification.

3. The system of Claim 1., wherein said third heat-transfer means energize sanitary-water heating.

4. The system of Claim 1., wherein said second means subject said sewage to pressurized liquid-phase sterilization.

5. The system of Claim 4., wherein said third heat-transfer means energize dwelling-space temperature-modification.

6. The system of Claim 4., wherein said third heat-transfer means energize sanitary-water heating.

7. The system of Claim 1., and further comprising fifth means for mineraliz-ing the nonvital-organics fraction of said sewage prior to its liquid-phase thermal-sterilization.

8. The system of Claim 4., and further comprising fifth means for mineraliz-ing the nonvital-organics fraction of said sewage prior to its pressurized liquid-phase thermal-sterilization.

9. The system of Claim 7., and further comprising sixth means to comminute macroscopic organic solids prior to said mineralizing.

10. The system of Claim 8., and further comprising sixth means to comminute macroscopic organic solids prior to said mineralizing.

11. The system of Claim 7., wherein said third heat-transfer means energize dwelling-space temperature-modification.

12. The system of Claim 7., wherein said third heat-transfer means energize sanitary-water heating.

13. The system of Claim 8., wherein said third heat-transfer means energize dwelling-space temperature modification.

14. The system of Claim 8., wherein said third heat-transfer means energize sanitary-water heating.

15. The system of Claim 9., wherein said third heat-transfer means energize dwelling-space temperature-modification.

16. The system of Claim 9., wherein said third heat-transfer means energize sanitary-water heating.

17. The system of Claim 10., wherein said third heat-transfer means energize dwelling-space temperature-modification.

18. The system of Claim 10., wherein said third heat-transfer means energize sanitary-water heating.

19. The system of Claim 1., wherein said first means include (a) a vessel receiving the sewage from a dwelling, (b) a filter dividing said sewage into a nonvital-organics slurry compon-ent and a liquid-remainder component essentially free of nonvital organics, (c) a collector receiving said liquid-remainder component, (d) a unit receiving said liquid-remainder component from said collec-tor, and (e) a homogenizer receiving said slurry-component, said second means include (f) a fuel source supplying preselected amounts of fuel to said homogen-izer wherein said slurry-component and said fuel are caused to form a mixture, (g) a burner to incinerate said mixture and generate high-temperature vapors and gases, and (h) conduit to transport said high-temperature vapors and gases through said liquid-remainder component contained in said unit in heat-transfer relationship therewith, and said third heat-transfer means include (i) first and second storage-vessels to receive said liquid-remainder component subsequent to said liquid-phase thermal-sterilization.

20. The system of Claim 19., wherein said unit is an autoclave in which said liquid-remainder component may be heated to a temperature higher than its atmospheric boiling-point essentially without undergoing a phase-change.

21. The process of treating and utilizing domestic sewage composed of human excrement and other organic and inorganic wastes entrained in transport water comprising the steps of (1) collecting the sewage in a container, (2) heating said sewage while maintaining it in the liquid phase to a temperature capable of freeing it of viable targeted pathogenic cells, spores and microorganisms entrained therein, (3) utilizing the thermal-energy contained in said sewage after said heating to energize at least one other thermally-motivated function normally associated with human domestic life, and (4) disposing of said sewage after said thermal-energy has been utilized and depleted.

22. The process of Claim 21., and further comprising the step of (5) mineralizing the nonvital-organics fraction of said domestic sewageas the next step following said collecting and preceding said heating.

23. The process of Claim 22., and further comprising the step of (6) dividing said domestic sewage into a nonvital-organics slurry compon-ent and a liquid-remainder component essentially free of nonvital organics as the next step following said collecting and preceding said mineralizing wherein said mineralizing of said nonvital-organics fraction is accomplished by raising the temperature of said nonvital-organics slurry component above its flash temperature thereby generating high-temperature vapors and gases, and said heating is accomplished by passing said vapors and gases through said liquid-remainder component in heat-transfer relationship therewith.

24. The process of Claim 21., wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification and sanitary-water heating.

25. The process of Claim 22., wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification and sanitary-water heating.

26. The process of Claim 23., wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification and sanitary-water heating.

27. The system of Claim 1., wherein said third heat-transfer means regenera-tively utilize said thermal-energy to energize dwelling-space tempera-ture-modification and sanitary-water heating.

28. The system of Claim 4., wherein said third heat-transfer means regenera-tively utilize said thermal-energy to energize dwelling-space temperature-modification and sanitary-water heating.

29. The system of Claim 7., wherein said third heat-transfer means regenera-tively utilize said thermal-energy to energize dwelling-space temperature-modification and sanitary-water heating.

30. The system of Claim 8., wherein said third heat-transfer means regenera-tively utilize said thermal-energy to energize dwelling-space temperature-modification and sanitary-water heating.

31. The system of Claim 9., wherein said third heat-transfer means regenera-tively uitlize said thermal-energy to energize dwelling-space temperature-modification and sanitary-water heating.

32. The system of Claim 10., wherein said third heat-transfer means tively utilize said thermal-energy to energize dwelling-space temperature-modification and sanitary-water heating.

33. The system of Claim 19., wherein said burner mineralizes said mixture by incineration thereby generating high-temperature vapors and gases.

34. The process of Claim 21., wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification.

35. The process of Claim 21., wherein said thermal-energy is utilized in step (3) to energize sanitary-water heating.

36. The process of Claim 22., wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification.

37. The process of Claim 22, wherein said thermal-energy is utilized in step (3) to energize sanitary-water heating.

38. The process of Claim 23, wherein said thermal-energy is utilized in step (3) to energize dwelling-space temperature-modification.

39. The process of Claim 23, wherein said thermal-energy is utilized in step (3) to energize sanitary-water heating.