System for purification of domestic household effluent

The invention provides a system 10 for treatment and purification of domestic household effluent, and for the elimination within said system of organic solid wastes, comprising elements 12 and 14 for separately collecting first and second constituents of the sewage of a domestic residential unit, lavatory sewage comprising said first sewage constituent, and bath, shower, wash basin, laundry, kitchen sink sewage and the like comprising said second sewage constituent, a first and a second dual-purpose vessel 22 and 24, each vessel having at least one inlet port 18 and 20 and at least one outlet port 26, 28, 30, 32 and being arranged so that during the time period that one of said vessels 22 receives said first sewage constituent and acts as a collector and settling tank, the remaining vessel 24 operates as an anaerobic reaction vessel, the vessel operating as an anaerobic reaction vessel carrying out a decomposition process during which the volume of sludge 34 contained therein is greatly reduced by conversion to compost and gas, a gas outlet 30, 32 being provided at the top of each of said vessels for the collection thereof, first valve means 16 for directing said first sewage constituent to whichever dual-purpose vessel 22, 24 is currently used as a collector and settling tank and for isolating the remaining dual-purpose vessel to convert the same to operate as an anaerobic reaction vessel, at least one aerobic reaction vessel 40 connected to receive an aqueous slurry containing floating organic solids from said collector and settling tank 22, at least one aerator 42 connected to said aerobic reaction vessel 40 for oxygenating said slurry, first pumping means 44, powered at least in part by gas generated in said anaerobic reaction vessel 24, for repeatedly driving said slurry from said aerobic reaction vessel 40 through said aerator 42.

TECHNICAL FIELD 
The present invention relates to purification of household effluent. More 
particularly, the invention provides a process and a system to purify 
effluents from a building or groups of buildings housing up to several 
hundred families, such purification being sufficient for purposes of 
toilet flushing, and permitted disposal of surplus water into available 
drainage conduits, while eliminating biologically degradable solids. 
BACKGROUND ART 
Nearly all prior art sewage purification systems require that sooner or 
later the system be closed down to allow removal of sludge that has not 
been fully treated and has accumulated in the processing vessels. Large 
municipal treatment plants have the equipment and personnel to carry out 
this work. However, small-scale systems intended for the use of a single 
house or housing blocks are better served by arrangements that almost 
completely dispose of organic solids and so do not require such servicing. 
As is known, environmental regulations are becoming increasingly stringent, 
and the legal disposal of wastes, whether as solids, liquids or even as 
gases, is becoming increasingly difficult and expensive. 
It is known that, besides carbon dioxide and minor quantities of other 
gases, methane is produced during the decomposition of sludge material. 
Typically, 0.35 m.sup.3 methane becomes available per kilogram of sludge 
decomposed. In the U.S., methane produced by cattle and expelled through 
their digestive systems is considered such an environmental nuisance that 
Congress has funded research to see what, if anything, can be done about 
this. Interestingly, methane has a higher heat value than any other common 
fuel gas, except for hydrogen. However, in almost all prior art systems, 
generated methane is discharged into the atmosphere, causing an unpleasant 
odor. In some localities municipal regulations prohibit discharge of such 
gases. 
Methods and apparatus for treating domestic effluents are disclosed in U.S. 
Pat. No. 4,172,034 (Carlsson, et al); U.S. Pat. No. 4,812,237 (Cawley); 
U.S. Pat. No. 5,114,586 (Humphrey) and U.S. Pat. No. 5,342,523 
(Kuwashima). 
Carlsson describes an apparatus which operates on an easy-flowing slurry, 
having a dry solids content of between 1-15%, preferably 5-10%. Such a 
dilute slurry unnecessarily extends processing time to achieve aerobic 
degradation in a reaction vessel with aeration; however, the Carlsson 
apparatus has the advantage of being compact. 
Humphrey discloses a complex sanitation system provided with many vessels, 
five of which have multiple air entry orifices. The resulting high air 
consumption necessitates the installation of a large air blower or 
compressor, leading to high running costs and a noise suppression problem. 
Another difficulty encountered in the Humphrey system is finding space in 
a residential building for all the described system components. 
Cawley describes and claims a process for purifying and recycling household 
waste waters, comprising the steps of (a) collecting a first wastewater 
stream from household kitchen sources; (b) anaerobically digesting said 
first wastewater stream in a first septic tank; (c) collecting a second 
wastewater stream from household laundry and bathing sources; (d) 
combining water from steps (b), (c) and (h); (e) anaerobically digesting 
water from step (d) in a second septic tank; (f) pumping water from step 
(e) over a biological sand filter under aerobic conditions; (g) pumping 
biologically filtered water from step (f) through an ultra-filter, thereby 
separating the biologically filtered water into a retentate stream and a 
permeate stream; (h) returning said retentate stream to step (d); (i) 
disinfecting said permeate stream; (j) returning a first portion of said 
disinfected permeate stream to household laundry and bathing facilities; 
(k) separating a second portion of said disinfected permeate stream into a 
low salt portion and a high salt portion; (l) returning said low salt 
portion to a household kitchen; and (m) disposing of said high salt 
portion. 
Kuwashima proposes a pair of separator tanks which are used alternately for 
separating floating or sedimenting material; the organic material is 
transferred for aerobic decomposition to a third tank. The device lacks 
means for breaking up large solids into small particles for efficient 
decomposition. 
DISCLOSURE OF THE INVENTION 
With this state of the art in mind, one of the objects of the present 
invention is to obviate the disadvantages of prior-art small-scale 
effluent treatment systems and to provide a system and process which 
internally eliminates organic solids to an--extent that under normal use 
manual disposal of residues will not be required in under ten years of 
operation if at all. 
It is a further object of the present invention to reduce the water 
consumption of a family in a building provided with such a system. Such 
reduction is reflected not only in water use charges, but also in lower 
charges for disposal of sewage, as the latter is often calculated as a 
proportion of water use charges. 
Yet a further object of the present invention is to eliminate the nuisance 
caused by discharging methane into the atmosphere, and to reduce energy 
consumption expenses by utilizing gases generated during decomposition 
processes as fuel for powering at least one of the pumps used in the 
system. 
The present invention achieves the above objects by providing a system for 
treatment and purification of domestic household effluent, and for the 
elimination within said system of organic solid wastes, comprising means 
for separately collecting first and second constituents of the sewage of a 
domestic residential unit, lavatory sewage comprising said first sewage 
constituent, and bath, shower, wash basin, laundry, kitchen sink sewage 
and the like comprising said second sewage constituent, a first and a 
second dual-purpose vessel, each vessel having at least one inlet and at 
least one outlet port and being arranged so that during the time period 
that one of said vessels receives said first sewage constituent and acts 
as a collector and settling tank, the remaining vessel operates as an 
anaerobic reaction vessel, the vessel operating as an anaerobic reaction 
vessel carrying out a decomposition process during which the volume of 
sludge contained therein is greatly reduced by conversion to compost and 
gas, a gas outlet being provided at the top of each of said vessels for 
the collection thereof, first valve means for directing said first sewage 
constituent to whichever dual-purpose vessel is currently used as a 
collector and settling tank and for isolating the remaining dual-purpose 
vessel to convert the same to operate as an anaerobic reaction vessel, at 
least one aerobic reaction vessel connected to receive an aqueous slurry 
containing floating organic solids from said first sewage constituent from 
said collector and settling tank, wherein the solid content is maintained 
at about 15-35%, the reaction being carried out at a temperature of 
between -6.degree. C. to 92.degree. C. while said slurry is maintained at 
a flowable constituency, at least one aerator connected to said aerobic 
reaction vessel for oxygenating said slurry, first pumping means, powered 
at least in part by gas generated in said anaerobic reaction vessel, for 
repeatedly driving said slurry from said aerobic reaction vessel through 
said aerator, to maintain the oxygen level in said aerobic reaction vessel 
at at least 1 p.p.m, a separation and settling vessel for receiving 
therein aerated and bio-aerobic reacted slurry from said aerobic reaction 
vessel, a first filtered outlet for removing purified water from said 
separation vessel, a second outlet means for pumping settled slurry 
particles from said separation and settling vessel to said dual-purpose 
collector and settling vessel, a lower storage vessel receiving said 
second constituent, upper storage vessel providing water for toilet 
flushing, and second pumping means for transferring said second 
constituent from said lower storage vessel to said upper storage vessel. 
In a further embodiment of the invention there is provided a treatment and 
purification system wherein said upper storage vessel is provided with a 
first water-receiving container having an open upper rim over which flows 
foam floating on water in said vessel together with overflow water 
therefrom, which overflow water and foam are then used for toilet 
flushing. 
Yet further embodiments of the invention will be described hereinafter. 
The present invention also provides for a method for the treatment and 
purification of domestic household effluent, and for the elimination 
within said system of organic solid wastes, comprising: 
a. separately collecting as a first constituent the lavatory sewage of a 
domestic residential unit, and as a second constituent the bath, shower, 
wash basin, laundry, kitchen sinks sewage; 
b. providing a first and a second dual-purpose vessel, each vessel having 
at least one inlet and at least one outlet port and being arranged so that 
during the time period that one of said vessels receives said first sewage 
constituent and acts as a collector and settling tank, the remaining 
vessel operates as an anaerobic reaction vessel, the vessel operating as 
an anaerobic reaction vessel carrying out a decomposition process during 
which the volume of sludge contained therein is greatly reduced by 
conversion to compost and gas, a gas outlet being provided at the top of 
each of said vessels for the collection thereof; 
c. providing first valve means for directing said first sewage constituent 
to whichever dual-purpose vessel is currently used as a collector and 
settling tank and for isolating the remaining dual-purpose vessel to 
convert the same to operate as an anaerobic reaction vessel; 
d. providing at least one aerobic reaction vessel connected to receive an 
aqueous slurry containing floating organic solids from said collector and 
settling tank, wherein the solid content is maintained at about 15-35%, 
the reaction being carried out at a temperature of between -6.degree. C. 
to 92.degree. C. while said slurry is maintained at a flowable 
constituency; 
e. providing at least one aerator connected to said aerobic reaction vessel 
for oxygenating said slurry; 
f. providing first pumping means, powered at least in part by gas generated 
in said anaerobic reaction vessel, for repeatedly driving said slurry from 
said aerobic reaction vessel through said aerator, to maintain the oxygen 
level in said aerobic reaction vessel at at least 1 p.p.m; 
g. providing a separation and settling vessel for receiving therein aerated 
and bio-aerobic reacted slurry from said aerobic reaction vessel; said 
separation vessel having a first filtered outlet for removing purified 
water therefrom and having a second outlet means for pumping settled 
slurry particles from said separation and settling vessel to said 
dual-purpose collector and settling vessel; 
h. providing a lower storage vessel receiving said second constituent; 
i. providing an upper storage vessel providing water for toilet flushing; 
and 
j. providing second pumping means for transferring said second constituent 
from said lower storage vessel to said upper storage vessel. 
In preferred embodiments of the present invention the reaction in the 
aerobic reaction vessel is carried out at a temperature of between 16 and 
42.degree. C. 
In especially preferred embodiments of the present invention there is 
provided a treatment and purification system, further comprising means for 
collecting, at source, a third kitchen water constituent and passing said 
kitchen water constituent through a stripping unit for separating organic 
and other waste components therefrom. Said preferred embodiments 
preferably also comprise means for feeding said separated organic and 
other waste components from said kitchen-water constituent to one of said 
dual-purpose vessels. In this manner garbage disposal units can be 
installed in the kitchen sinks with the knowledge that the effluent 
thereof will not block drainage systems since the waste components will be 
processed and directed to one of said dual-purpose vessels to undergo an 
anaerobic decomposition in said embodiment, said dual purpose vessels are 
provided with cellulose digesting bacteria which do not interfere with the 
anaerobic bacteria found therein and work. 
It will be realized that substantial savings can be achieved in planning 
residential neighborhoods with the elimination of a sewage piping network. 
Householders will save paying for water for directed use and by not being 
charged for sewage disposal. A saving of 60 liters of water per day, per 
person, can be expected. High quality water will thus be preserved for 
those uses that require the same, mainly for drinking, food preparation 
and washing. 
The invention will now be described in connection with certain preferred 
embodiments with reference to the following illustrative figures so that 
it may be more fully understood. 
With specific reference now to the figures in detail, it is stressed that 
the particulars shown are by way of example and for purposes of 
illustrative discussion of the preferred embodiments of the present 
invention only and are presented in the cause of providing what is 
believed to be the most useful and readily understood description of the 
principles and conceptual aspects of the invention. In this regard, no 
attempt is made to show structural details of the invention in more detail 
than is necessary for a fundamental understanding of the invention, the 
description taken with the drawings making apparent to those skilled in 
the art how the several forms of the invention may be embodied in 
practice.

DESCRIPTION OF PREFERRED EMBODIMENTS 
There is seen in FIG. 1 a system 10 for treatment and purification of 
domestic household effluent, and for the elimination within said system of 
organic solid wastes. 
Separate drainage means 12, 14 are provided for separately collecting first 
and second constituents of the sewage of a domestic residential unit. 
Lavatory sewage comprises the first sewage constituent, and bath, shower, 
wash basin, laundry, kitchen sink sewage and the like comprises the second 
sewage constituent. 
Drainage means 12 are connected to first valve means 16 which in turn is 
connected to the inlet ports 18, 20 of a first and a second dual-purpose 
vessel 22, 24. Each of these vessels is also provided with two outlet 
ports 26, 28, 30, 32, and are identical to each other in construction. By 
use of first valve means 16 the vessels 22, 24 are arranged to have 
alternate functions; during the time period that the vessel 22, for 
example, acts as a collector and settling tank, the remaining vessel 24 
operates as an anaerobic reaction vessel for generating compost. 
The vessel 24 operates as an anaerobic reaction vessel when isolated by 
first valve means 16 and 20, and carries out a decomposition process 
during which the volume of sludge 34 contained therein is greatly reduced. 
The upper outlet port 32 comprising a one-way valve (not shown), is used 
for the removal of fuel gas 36 generated during the decomposition process. 
Utilization of gas 36 will be described with reference to FIG. 2. A 
gas-tight charging door 38 is provided in vessels 22, 24 so that 
biologically degradable material, for example animal excrement, can be 
loaded during start-up. 
First valve means 16 directs the first sewage constituent to whichever 
dual-purpose vessel, 22 in the present example, is currently used as a 
collector and settling tank. First valve means 16 are operated when a 
substantial quantity of solids have accumulated in the vessel 22 being 
currently used as a collector and settling tank. The time period between 
successive operations of valve means 16 exceeds one year, and is typically 
three years, under normal operating conditions. 
An aerobic reaction vessel 40 is connected to receive an aqueous slurry 
containing floating organic solids from the collector and settling tank 
22. The solid content therein is maintained at about 15-35%, the reaction 
being carried out at a temperature of between -6.degree. C. to 92.degree. 
C. The slurry is maintained at a flowable constituency. 
An aerator 42 is connected to the vessel 40 for oxygenating the slurry. The 
high solid content stated makes for efficient aeration. The wide 
temperature range permitted corresponds to the survival temperature of 
active bacteria which cause decomposition of organic wastes. 
First pumping means 44, such as a centrifugal immersion pump, repeatedly 
drives slurry from the aerobic reaction vessel through aerator 42 to 
maintain the oxygen in vessel 40 at at least 1 ppm. First pumping means 44 
is powered at least in part by gas generated in the anaerobic reaction 
vessel 24. 
Advantageously first pumping means 44 are arranged to cause vigorous 
agitation to effect size reduction of suspended solids in the slurry. A 
simple method of achieving this end is to use a powerful pump engine and 
to drive the pump at a speed in excess of that needed with regard to the 
requirements of aeration alone. 
A separation vessel 46 receives aerated and bio-aerobic reacted slurry from 
the aerobic reaction vessel 40. 
Further settling and solid particle aggregation takes place in this vessel. 
A sludge pump 48 capable of handling such material transfers same through a 
second outlet means 50 provided for pumping such particles from separation 
vessel 46 via first valve means 16 to dual-purpose collector and settling 
vessel 22, in the shown example. 
A first filtered outlet 52 is provided for removing purified water from the 
separation vessel 46. Advantageously the filter 54 is provided with means 
for automatically clearing filter plate blockages. The quality of the 
purified water is determined by the quality of the filter unit 54. 
A lower storage vessel 56 connected to drainage means 14 receives the 
second constituent. 
An upper storage vessel 58 provides water for toilet flushing. Vessel 58 is 
fed by means of second pumping means 60 which transfers water from the 
lower storage vessel 56. Water in excess of that required for toilet 
flushing is sufficiently purified to be passed to drainage 62. If vessel 
58 requires more water than provided by the system at any particular time, 
then additional water can be provided to the upper storage vessel 58 from 
the water main (not shown). 
With reference to the rest of the figures, similar reference numerals have 
been used to identify similar parts. 
Referring now to FIG. 2, there is seen a detail of the same treatment and 
purification system 10 described with reference to FIG. 1. 
Gas 36 is produced in the dual purpose vessels (only one of which, 24, is 
shown) and is collected in tank 64, compressed in compressor 66, stored in 
tank 68 at compressed pressure, and used at least in part to power first 
pumping means 44 which drives slurry through the aerator 42. System 10 
thus operates while requiring less electricity, and more important in 
urban areas, reduces the generation of unpleasant odors. 
The primary component, typically 57-67% of the generated gas, is methane. 
The remainder is almost all carbon dioxide. The heating value of such a 
gas mixture is about 5000 to 6500 kcal/cubic meter. The compressed gas is 
fed into an internal combustion engine 70 having enhanced protection 
against internal corrosion. Engine 70 is connected to first pumping means 
44, which in turn is also connected to be driven by an electric motor 72 
when gas 36 is for any reason unavailable, for example during start up. 
Alternatively, or in addition, said gas can be converted to electricity, 
or be used in a burner for directly heating water. 
FIG. 3 shows a detail of a second embodiment of a purification system 74 
having components for size reduction of solids contained in the first 
sewage constituent. 
Pumped slurry is repeatedly impacted against an array of stationary cutter 
blades 76 to effect size reduction of suspended solids in the slurry 
moving around the aeration circuit. Particle size is thereby 
advantageously reduced to a size of up to 1.5 millimeters, the resultant 
increase in solids exposed surface area leading to effective aeration. 
Seen in FIG. 4 is a detail of a third embodiment of a purification system 
78 provided with further filter means. 
The water outlet port 80 of the lower storage vessel 82 is connected to a 
filter 84 for the removal of solids from water passing therethrough. Water 
passing the filter is stored in the upper storage vessel 86 and is used 
for toilet flushing. Excess water is available for horticultural purposes 
87. 
While there is no objection to the inclusion of small solids for flushing, 
it is nevertheless advantageous to remove such solids to prevent 
malfunctioning of the flush tank mechanism 88. 
Referring now to FIG. 5, there is seen part of a preferred embodiment of a 
purification system 90 having a special arrangement of the upper storage 
vessel 92. 
An upper storage vessel 92 is provided with a first water-receiving 
container 94 having an open upper rim 96. Water in the container 94 
includes fats, soaps and detergents which originated in the second sewage 
constituent. A pump 97 agitates the water in the container 94, and causes 
foaming. The foam 98 floats on the water in the container 94, and together 
with overflow water therefrom, flows down into the tank 100. Overflow 
water and foam 98 is withdrawn from the tank 100 as needed for toilet 
flushing. 
Shown in FIG. 6 is an embodiment generating electricity by use of a water 
turbine 102. 
A treatment and purification system 104 generates electricity for use in 
the system, by means of a turbine 102 in a water pipe 106 leading down 
upper storage vessel 108. Rechargeable electric batteries 110, connected 
to a pump motor 112, provide power storage, so that first pumping means 
44, seen in FIG. 1, can be operated when gas or mains power is 
unavailable. In additional embodiments (not shown) supplementary 
electricity is generated by solar cells or by a windmill, the choice 
depending on which is the more suitable for the location in which the 
system is to be installed. 
Referring now to FIG. 7, there is depicted a detail of an embodiment of the 
treatment and purification system 116 having provision for the transfer of 
sludge 34. The first and second dual-purpose vessels 118, 120 are provided 
with an additional inlet 122, 124 to receive, and an additional lower 
outlet 126, 128 to discharge sludge 34 accumulating at the bottom of 
vessels 118, 120. Each vessel is provided with a pump 130, 132 capable of 
handling such material. Sludge transfer is effected from the dual-purpose 
vessel (for example 122) to be used for storage and settling to the vessel 
(124 in the present example) to be used for anaerobic decomposition. In 
the present embodiment activation of the appropriate pump (130 in this 
example) is effected through a control panel 134 and is automatically 
triggered by movement of first valve means 136. 
Referring now to FIG. 8, there is seen a block diagram representation of a 
system 138 comprising means 140 for separately collecting at source a 
third kitchen-water constituent 142 which is passed through a stripping 
unit 144, which can be either a static or dynamic filtering unit for 
separating organic and other waste components 146 therefrom. In said 
figure the remaining components are the same as those described with 
reference to FIGS. 1 and 2. 
As will be realized, water exiting filter and settling unit 46 and entering 
storage 56 can not only be recycled by pump 60 for lavatory use, but can 
also exit the system to be available for other uses, depending on water 
purity. 
As stated hereinbefore, such an arrangement enables the effective use of 
garbage-disposal units installed in kitchen sinks. 
In this embodiment dual purpose vessel 24 is provided not only with 
anaerobic bacteria, but also with cellulose-consuming bacteria such as 
Trichonympha, which can function in conjunction with said anaerobic 
bacteria without either interfering with the other. 
FIG. 9 depicts a part of a further system 86, similar to that described 
above with reference to FIG. 1, however, speeding up the anaerobic 
decomposition process. An anaerobic decomposition reactor 88 is provided 
with a spaced-apart triple wall 90, 91, 92, forming two concentric outer 
compartments 93 and 95 around each of said vessels 88 for introduction 
therein of fluids for regulating the temperature within said vessels. 
Preferably, compartment 93 adjacent to said vessel 88 is filled with an 
oil fluid 97 and compartment 95 is connected by inlet and outlet conduits 
98, 99 to a source 94 of aqueous fluid 96 for heating the reactor 88, 
which fluid is heated by a heat source 89. Heat can be provided either 
electrically, or by burning a fuel, suitably some of the methane 74 
produced in the reactor 88. The heating of the reactor 88 speeds up the 
decomposition process and also enables the decomposition of materials 
which do not disintegrate significantly at room temperature. This 
arrangement is also preferred for systems installed in cold climates. In 
addition, the rate of decomposition within reactor 88 can be regulated by 
controlling the temperature of aqueous fluid 96 introduced into 
compartment 95, which aqueous fluid then serves to heat or cool oil fluid 
97, which in turn heats or cools the contents of reactor 88, hot water 
being removable from compartment 95 and being replaceable by cooler 
aqueous fluid as desired, optionally using further inlet and outlet 
conduits (not shown). 
It is to be noted that the conduits interconnecting the various components 
of the system and leading therefrom can be formed as double-wall conduits 
and the system can further comprise means for introducing heated water 
between the inner and outer walls of said conduits to heat the contents of 
the fluids flowing therethrough. 
In addition, the gas produced in reactor 88 can be fed to a burner for 
heating water to be circulated between the inner and outer walls of said 
conduits, which heated water can also be introduced under pressure into 
said conduits to flush the same when necessary. 
It will be evident to those skilled in the art that the invention is not 
limited to the details of the foregoing illustrative embodiments and that 
the present invention may be embodied in other specific forms without 
departing from the spirit or essential attributes thereof. The present 
embodiments are therefore to be considered in all respects as illustrative 
and not restrictive, the scope of the invention being indicated by the 
appended claims rather than by the foregoing description, and all changes 
which come within the meaning and range of equivalency of the claims are 
therefore intended to be embraced therein.