Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to apparatus for the biological
treatmc-nt of waste ~ater sewage and the like containing
organic matter.
It is ~ell known to treat ~Jaste water sewage and the
like by the biological organisms contained in the organic
matter in the ~aste water, which decompose the waste thereby
purifying the water. An accelerated form of such biological
action is produced in equipment in which a plurality of
support members, typically disc like rotors, are rotated into
and out of the waste water at a slow rate of rotation.
Biological organisms in the water will adhere to such support
members, and as the support members are then raised upwardly
into the air, the organisms will have free access to the
oxygen and other nutritive elements in the air and their
growth is thereby substantially accelerated. A layer of such
- organisms will rapidly build up on the supports, and as the
organisms are then again rotated through the waste water,
the decomposition action produced by such organisms is
greatly accelerated. In this way, it is possible to treat
substantial volumes of waste water in relatively small tanks.
Various problems are encountered in the design of
such tanks however. Conventionally, the treatment takes
place in three stages namely a primary settlement, a
decomposition stage and a final settlement or clarifica*ion
25 stage. The provision of three separate tanks involves the -
use of a relatively large amount of space, which may disfigure
the landscape, or render the adjacent area unsuitable for
other use. Odors emanating from some types of equipment
may be noticeable in the immediate surroundings. Consequent-
30 ly, this type of equipment is usually located at a distance
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from buildings, or other areas of the landscape which may be
usecl for recreation for example. In addition it is clearly
desireable to minimize work on excavation, pouring foundations
and the like.
Various attempts have been made to render the equip-
ment more compact. In particular attempts have been made to
combine two or more tanks together to make the equipment more
readily concealed in the landscape. This however has not
been carried out without some impairment of the overall
10 decomposition process and it has~not been totally successful. ~ -
In addition, the servicing of this type of equipment
should preferably be kept to a minimum and the design of
such equipment should preferably be adaptable to a wide range
of different sizes of tankg 80 that installations of widely
ranging capability should be available with a minimum of
engineering requirement.
One of the more unusual problems encountered with
this type of equipment is the problem of maintaining a
satisfactory layer of active biological organisms on the
-rotating support members during all conditions of use.
When the equipment is continuously being supplied -
with quantities of raw waste water and the like, it is found -
that the biological organismsj will grow rapidly and maintain
themselves in a highly active state. As the layers of such
organisms accumulate on the supports become excessively
thick, they will gradually flake off the supports, and fresh
layers of organisms will then adhere to the supports and the
entire growing and flaking cycle takes place continuously.
However, when the supply of raw waste water is
discontinued for any length of time the organisms wither
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and die, and the waste water contained in the equipment may
eve~ start to become stagnant. When fresh raw waste water
i8 then supplied to the equipment once more, it takes an
apprec~able time for the layers of organisms to re-establish
themselves and consequently, for an appreciable length of
time no decomposition treatment is taking place.
It has suprisingly been found that this problem
can be overcome by ensuring that a certain degree of
circulation takes place between the decomposition tank and
the primary settlement tank so that even during extended
periods of shortage of fresh raw waste water, the organisms
in the decomposition tank are continuously supplied with
nutrients from the primary settlement tank. In this way,
as soon as further supplies of raw waste waters are received
1~ in the equipment, the organisms are immediately available
to carry out their decomposition function.
Such a self maintaining feature has been absent
from previous installations of this general type, and is a
particularly advantageous feature of the present invention.
The invention therefore will be seen to generally
provide apparatus for the biological treatment of waste
water, sewage and the like, containing organic matter, and
having a settling tank havlng side and end walls and a
bottom wall for collecting solid matter from said waste
water, and for containing a predetermined volume of said
waste water, a decomposition trough, said trough being
shaped and positioned with at least a portion of said
trough within an upper portion;of said settling tank and
extending from end to end thereof at least partially below
the liquid level in said tank, partition means located in
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said trou~h at spaced intervals therealong, and defining
separate consecutive treatment compartments, and weirs in
said partition means communicating between said compartments
in sequence, alternate weirs being offset whereby to establish
a meandering liquid flow path through said compartment$, a
plurality of biological organism support members, mounted
for rotation on a common shaft, and arranged in spaced apart
groups, there being at least one said group located at least
partially in each of said compartments, with said shaf.t
means extending longitudinally along the length of said
trough, and incorporating power operated drive means for
510wly rotating the same, opening means in said settling
tank for the introduction of raw waste water thereto at one
end thereof offset to one side of said trough and above the
lowermo9t portion of said trough, inlet weir means in a
side of said trough, communicating between said settling
tank and a first said compartment of said trough at a -
predetermined level and at a side and end of said tank remote
from said opening means whereby to establish a liquid flow
path in said tank from said opening means, beneath said
trough, to said inlet weir means, longitudinal slotted -
opening means communicating between said first compartment
of said trough and said settling tank below said predetermined
level whereby to establish a liquid recycle flow path from
said settling tank into said first compartment of said
trough at a predetermined level, through said inlet weir
means, and then downwardly within s,aid first compartment and
through said slotted opening means back into said settling
tank below said predetermined level, outlet opening means
at a last said compartment of said trough for flow of
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treated water therefrom.
One of the significant features of the invention is
the provision of apparatus of the type described wherein the
bacl;eria support members are in the form of a plurality of
rotors mounted on a common shaft, and including paddle means
mounted on at least some of said rotors in the first
compartment, whereby to induce flow of liquid from the first
compartment of the trough downwardly into the settlement tank;
such downward flow being balanced by return flow from the
settlement tank back into the first compartment of sald
trough through the inlet weir.
It is a further and related objective of the
invention to provide apparatus having the foregoing
characteristics wherein the final settlement tank is separate
lg from the primary settlement tank and trough, and wherein the
shaft means from the decomposition tank extends over it, to-
ward the final settlement tank, whereby suitable motor drive
means may be mounted thereon. ~ ~-
The various features of novelty which characterize
the invention are pointed out with particularity in the claims
annexed and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages
and the specific objects attained by its use, reference
should be had to the accompanying drawings and descriptive
matter in which there are illustrated and described preferred
embodiments of the invention.
In the drawings:
Fig. 1 -- is an isometric view of the primary and
final settlement tanks of the invention with portions broken
away to reveal interior structure and with one group of
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organism support members in position;
Fig. 2 -- is a top plan of the apparatus of Fig. 1
sectioned along the line II-II of Fig. 4 with the support
members in place;
Fig. 3 -- is a side elevational view, sectioned along
the line III-III of Fig. 2;
Fig. 4 -- is a section along the line IV-IV of Fig.
3;
Fig. 5 -- is an enlarged isometric view of a group
of bacteria support members in cross-section, and ~ -
Fig. 6 -- is an isometric view of a group of
bacteria support members with a modified form of paddle
mounted thereon.
Referring now to the drawings, the embodiments of the
invention which is illustrated therein for the expository
purposes of this submission, and without limitation, will be
seen to comprise a primary settlement tank lO of generally,
open-topped, hollow rectangular shape. It is formed of a
substance suited to its function, e.g. concrete.
A trough 12 is located in the upper part of the
tank lO with its top no lower than the top of tank 10 and
preferably slightly higher. The trough 12 is typically,
although not necessarily, of sheet metal construction, formed
in an essentially semi-cylindrical shape and will preferably
incorporate end walls 14 which may butt up against opposite
ends of tank lO, or even be formed integrally therewith,
as shown. In this way liquid can flow from one side of the
tank 10 to the other only by passing under the trough 12.
Since most of the trough is below the normal operating liquid '
level for tank lO, this means that flow must ta~e place
downwardly beneath trough 12.
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Within the trough there are provided essentially
flat partitions 16, 18 and 20 which may be of sheet metal
and of generally semi-circular shape mounted on edge along
the length of the trough 12, at equally spaced intervals
defining four treatment compartments or zones 22, 24, 26 and
28. Gates or weirs 16', 18' and 20' are formed in the
partitions 16, 18 and 20, at alternate corners thereof,
whereby fluid flowing from one compartment to another must
follow a generally zigzag meandering path, as shown, thereby
inducing maximal exposure of the fluid to the treatment
apparatus to be described.
Within each of the zones or compartments, there is
provided a group 30 of bacteria support members. As better
- shown in Fig. 4, the bacteria support members each comprise
a generally circular plate-like disc 32 of any suitable
material, mounted on a common shaft 34, and preferably
interconnected around their edges by means such as the
spacers 36 shown in Fig. 5. The discs 32 may be,for example,
of thermo plastic material, either in a generally waffle
plate design, or having a corrugated surface, or may be in
the form of a mesh or open weave of thermo plastic material,
such as to provide a maxium wetted surface area for each such
disc 32. The discs 32 will not normally be required to
carry extreme loads and can be made of quite thin material
so as to permit accomodation of a relatively large number
thereof in each treatment zone; only a few being shown in
the drawing for the sake of clarity.
Shaft 34 is preferably supported in any suitable
bearing means such as 38, at either end of trough 12.
A final settlement tank 40 is provided wh~ch, in
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this embodiment of the invention, is shown separated from
the primary tank 10 and trough 12. The settlement tank 40
can be manufactured of sheet metal, or poured concrete or
any other suitable material. Preferably, as shown in Fig. 2,
an end portion of shaft 34 will extend over an upper edge of
tank 10, and suitable drive means 42 may be provided and
mounted on such edge of tank 10 and coupled to the shaft 34
through any suitable gear reduction mechanism (not shown)
the details of which require no description, but which will
suffice to rotate the shaft 34 at a suitable speed usually in
the region of two to six revolutions per minute.
A raw sewage inlet 44 is provided at an upper corner - ~ ~-
of primary tank 10 adjacent to the final settlement tank 40.
At the diagonally opposite end of tank 10, a transfer port
or inlet weir 46 i5 provided in the side wall of trough 12
communicating with the first compartment or tank zone 22.
In accordance with the invention such port or weir 46 will
be on the side of trough 12 opposite from the raw sewage
entry 44 of tank 10, and at the opposite end thereof. In
this way, fluid entering port 44 is forced to flow the entire
length of tank 10 and also to pass underneath trough 12 and
well or flow upwardly on the other side thereof before it
can pass into trough 12.
An elongated slotted opening 48 is provided along
the bottom of trough 12, in compartment 22 only. Any solids
passing into trough 12, from tank 10, can thus return to
tank 10 from the first compartment 22.
From the last compartment 28, a transfer passage or
duct 50 communicates between compartment 28 of trough 12,
and the final settlement tank 40.
A clarified liquid outflow port 52 is provided
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as shown in the opposite side of tank 40 from (and preferably
offset with respect to) the port or duct 50 whereby clarified
liquids may be removed from tank 40.
In order to assist in ensuring a thorough contacting
between the rotor disc 32 and the liquid in the various com-
partments of trough 12, some form of liquid disturbers may
be provided on the rotors 30, such as the paddles 54. The
paddles also sweep around the inner su~face of the trough 12,
and dislodge any solids or slime therefrom. The particular
design of the paddles 54 may vary widely depending upon the
design requirements of the particular unit. In addition, the
paddles 54 on the rotor 30 in the first zone 22 will also
materially assist in procuring flow of liquids and solids
downwardly through the slotted opening 48 into the tank 10.
It will of course be appreciated that any such down-
ward flow of liquids or solids will be immediately matched by
a return flow of an equal volume of liquids from the tank 10 ~:
into the trough 12, usually through the weir 46 or in some
circumstances back up through the opening 48 itself. In this
way, organic material is constantly being supplied to the
trough 12, even during relatively extended periods of inactivity.
It will be appreciated that the final settlement
tank 40 may also incorporate a chlorination zone indicated as
60 in Fig. 1. Such a chlorination zone would essentially
consist of a small partition separating a corner of the
settlement tank 40 from the remainder, and incorporating any
suitable mechanical chlorinator such as are well known in
the art and require no further description.
Any suitable form of cover, such as the semi-
cylindrical dome-shape cover 62 may be provided over the
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ta~',c 10 and trough 12.
Generally speaking the final settlement tank 40 may
be covered with any suitable form of flat cover plate (not
shown) the details of which are well known in the art.
Before touching on the operation of the apparatus
described, it is desired to affirm, as will indeed be obvious, ~
that various distortionshave been incorporated into the ~ ~-
drawing for the sake of clarity. ;
In operation, untreated waste water and sewage will
be introduced intermittently through the port 44 where it
will flow into the tank 10. Once a working level of liquid
has been achieved in tank 10, liquid will then flow in a
path along the tank 10 and under the trough 12, welling up
on the other side of the trough 12 and flowing through the
weir or gate 46. The liquid will then flow into the trough
12 filling up the various compartments 22, 24, 26 and 28
until they are filled to essentially the same liquid level
as the tank 10. Once the normal working level has been
achieved, then flow of liquid will take place in response to
the introduction of additional raw waste water at the port
44, but will otherwise remain essentially static.
The downward, diagonal,and lengthwise flow path of
liquids in tank lO,tends to promote the deposit of solids
in tank 10, leaving at least partially clarified liquids to
pass into trough 12.
The shaft 34 is rotated continuously at a speed which
may be selected for the most efficient build-up of bacteria
for any given type of waste water. Generally speaking the
speed will be somewhere between two and six revolutions per
minute, although the speed may be higher or lower depending
upon the particular make-up of the waste water being supplied
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to the installation.
As the discs 32 rotate through the liquid in the
trou~h 12, they will acquire a liquid film, containing
bacteria from the liquid, and as the discs 32 rotate
through the air the liquid will be dried, leaving the
bacteria adhering to the rotors 32. Such bacteria, being
thus suspended in air will grow very much more quickly than
they would grow in the liquid medium, and a film of such
actively growing bacteria will thus build up on the discs -~
10 32 of the rotors 30. The action of the bacteria as they ~-
pass through the liquid in the trough 12 is to actively
decompose the organic materials and contaminants contained
in the liquid and provide a purifying action.
The layer or film of bacteria on the disc 32
gradually increases in thickness until the layers flake
away and fall into the liquid in the trough 12, at which
time fresh bacteria are deposited on the disc 32 and the
entire cycle takes place once again. The flakes of bacteria
returning to the liquid will either flow downwardly through
the slit 48 into the tank 10, or else will flow along the
trough 12 in the zigzag flow path around the partitions 16,
18 and 20, as described and illustrated.
The flow path of the liquid along the trough 12
takes place around the opposite corners of the partitions
25 16, 18 and 20, from the first zone through successive zones
to the last zone 28. In the last 28, the liquid flows
through the port or weir 50 into the final settlement tank
40. The final settlement tank 40 permits settlement of any
further solids, and any suspended flakes of bacteria and the
like to settle out into the bottom of the tank 40, and
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clarified liquid will then be free to flow through the
outlet gate or weir 52. Depending upon the requirements of -~
particular municipalities, such clarified water may either
be discharged directly into bodies of water, water courses
and the like, or else may be chlorinated, in for example the
chlorination zone 60 being discharged, or may even in
certain circumstances require further treatment before being
returned to the water supply.
When supplies of raw waste waters are being passed -.
more or less continuously to the tank 10 then flow will take
place through the tank 10 and trough 12 and into the final
settlement tank 40 more or less continuously in response to
such flow volumes as are introduced.
In this case, the action of the bacteria build-up
and flake away in the trough 12 is more or less continuous
as described above.
However, during periods of inactivity or only
limited use when supplies of fresh waste water to tank 10
are reduced or indeed discontinued for any extended period
of time, then the action of the rotors 30, and the disturbers ~ -
or paddles mounted thereon, in the first zone 22, will be -
such as to provide a continuous recirculation flow of
liquid from the compartment 22 downwardly through the slotted
opening 48 into the tank 10, and return flow from the tank
10 back through the gate or weir 46 or opening 48 into the
~ough 12. In this way, there is a continuous exchange of
liquid taking place between the trough 12 and the tank 10.
Thus during such periods of inactivity, the bacteria layers
on the rotors 32 will be able to regenerate themselves
continuously due to the presents of nutrients in the water
941 P/2C~ - 12 -
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continuously circulating to and fro from the tank 10.
Moreover, the recirculation also transfers aerated
liquid from trough 12 to tank 10 thus usefully oxygenating,
to a degree, the contents of the latter.
As has been explained, such recirculation is created
by so to speak "sweeping" compartment or zone 22 with the
paddle 54 in the described manner. However, it is possible to
procure substantially the same recirculation with the
alternative form of paddle shown as fin 65 located on and
projecting from each group 30 of discs 32; being located on a
chord or diameter of at least one outside disc 32 as shown
on Fig. 6; this alternative being provided to meet situations
in which the lateral dimensions of trough 12 are somewhat
critical.
The foregoing is a description of the preferred
embodiment of the invention which is given here by way of
example only. The invention is not to be taken as limited
to any of these specific features as described, but
comprehends all such variations thereof that has come within
the scope of the appended claims.
3o
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