Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF r~E INVENTION
A Field of the Invention
The present invention relates to water treatment, and
more particularly to an improved package water treatment plant
used to produce drinkable water from impure water.
A package water treatment plant is appropriate for use
in small community water systems, resort areas or construction
and lumber camps located in remote areas. A package water
treatment plant which is easily maintained and operated by
unskilled individuals is preferable over larger more complex
systems requiring continuous maintenance and supervision. In
particular, there is a definite need for package-type water
treatment plants which can accommodate flows from about 300 to
6000 gallons per hour and can operate on a continuous daily
basis. The size of a package water treatment plant is important,
and it is desirable to provide a plant which may be readily
moved from one area to another depending upon needs.
While prior art water treatment plants have been
proposed, the present invention contemplates an improved package
water treatment plant for producing drinkable water from impure
water in which the plant is constructed of generally rectangular
configuration and includes a plurality of coagulation chambers
for receiving impure water and mixing same with coagulant chemi-
cals in order to generate floc to be transported to a primary
settling tank. The primary settling tank is the first step of a
two-step sedimentation process. Sludge forms on a bottom V-shaped
surface of the primary settling tank and the water is transported
upwardly over a boundary wall to a secondary settling tank. The
secondary settling tank incorporates a plurality of inclined
settling tubes coextensively arranged, each having a generally
chevron-shaped cross section to expedite the settling of floc
downwardly to a V-shaped bottom surface in the secondary settling
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tank. After passing upwardly through the inclined settling
tubes, the water is then transported to a tertiary settling tank
which incorporates a sand and gravel filter. After passing
downwardly through the filter, the clarified water is discharged
through an underdrain assembly into a storage tank where a
bacteria killing supply may be added thereto for a predetermined
time interval. The water is then available for drinking purposes.
B Descri tion of the Prior Art
P
A package water treatment plant is disclosed in Cana-
dian Patent 692,543. The water treatment plant includes a
cylindrical shell disposed within a semicircular settling tank.
The cylindrical shell incorporates a plurality of coagulation
chambers arranged in continuous communication for eventual
discharge of influent impure water into the settling tank. The
settling tank discharges water therefrom into a filter which
uses sand as the filtering media. After passing through the
sand filter, the water is then transported to a storage tank.
The water treatment plant disclosed in this patent does not
employ tube settlers nor utilize V-shaped bottoms in the sedimen-
: 20 tation regions.
In U.S. Patent 3,768,648, there is disclosed an im-
proved settler assembly which utilizes a plurality of inclined
passages of chevron cross-sectional configuration. The chevron
configuration provides a higher critical flow rate than passages
having square, circular, hexagonal and the like cross-sectional
configurations. While the tube settlers of this patent are
described as being used for separating suspended material from a
fluid stream, use is not indicated in a package-type water
treatment plant.
SUMMARY OF THE INVENTION
The package water treatment plant of the present
invention provides a unit for producing drinkable water from
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impure water. Specifically, the present invention incorporates
a plurality of coagulation chambers in communication with a
pr mary settling tank which in turn is in communication with a
secondary settling tank. The secondary settling tank incorpor-
ates a plurality of inclined coextensively arranged chevron
cross-sectional settling tubes which greatly increase the rate of
sedimentation of the impure water for subsequent delivery to a
third settling tank. The third settling tank incorporates a
typical sand filter for removing or catching particles before the
water is channeled into a storage tank. The storage tank is
arranged to permit a bacteria killing source to be discharged
into the stored water.
A primary object of the present invention is to provide
hydraulic turbulence, designed into the fluid transport system,
such as to impart to the water the agitation necessary for
complete mixing, rapid growth of floc and rapid settling of a
floc blanket. The major proportion of floculated material is
removed initiall~v in the sedimentation stage and the residue
deposited on generously sized settling surfaces where it is
~0 removed during backwash. After filtration through a sand filter,
the water may be chlorinated and held for a sufficient time
before becoming available for consumption.
An object of the present invention is to provide a
package water treatment plant in which both the primary and
secondary settling tanks have generally V-shaped bottoms in order
to provide for better sludge removal. A V-shaped bottom will
give better sludge removal from a manifold in the bottom of the
tank.
Another object of the present invention is to incorpor-
ate chevron cross-sectional tube settlers in a secondary settling
tank in order to increase the rate of sedimentation in the tank.
A further object of the present invention is to provide
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a package water or sewage treatment plant which utilizes generally
rectangular compartments in the coagulation chambers, settling
tanks, etc. A generally rectangular configuration increases
detention time for a plant of a given length and width.
Still another object of the present invention is to
provide a package water treatment plant which is designed to
accommodate the ready attachment thereto of a horizontally
arranged catwalk or the like for maintenance or observation
purposes.
Additional objects of the present invention reside in
the specific construction of the exemplary apparatus hereinafter
particularly described in the specification and shown in the
several drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Novel features of the improved water treatment plant in
accordance with the present invention will be more readily under-
stood from a consideration of the following description taken
together with the accompanying drawing, in which a preferred
adaptation is illustrated with the various parts thereof identi-
fied by suitable reference characters in each of the views, andin which:
FIG. 1 is a perspective view of the water treatment
plant illustrating the use of a catwalk attached thereto;
FIG. 2 is a side view of the water treatment plant
shown schematically; and
FIG. 3 is a cross-sectional view of the tube settlers
shown in FIGS. 1 and 3.
, .
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DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2, a package water treatment
plant of the present invention is generally designated at 10.
Components of the package water treatment plant 10 will be
described preceding a particular description of an actual treat-
ment process using the principles of the present invention.
Package water treatment plant 10 is generally rectangu-
lar and consists of side walls 12, 14 and front and rear walls
16, 18. The walls are joined in a manner such as to define a
generally rectangular box. A mixing chamber 20 is arranged to
cooperate with coagulation chambers 22, 22_, 22b and 22c.
Refillable or portable chemical tanks 24, 24_ and 24b are arran-
ged to supply chemical coagulants to mixing chamber 20 via
appropriately arranged transporting hoses 17, 17a and 17b which
are connected from chemical tanks 24, 24a and 24b through pumps
25, 25a and 25b to manifold 26. A primary settling tank 28 is
disposed between a primary settler wier or launder 30 and wall 23
of the coagulation chambers. A plurality of inclined chevron
cross-sectional settling tubes are generally indicated at 32 and
are disposed in an upper portion of secondary settling tank 33.
A sand filter 35 is arranged in compartment 34 directly preceding
a backwash storage and chlorinated water reservoir 36. A sewage
treatment plant will have the general configuration as shown in
the drawings while a water treatment plant will have a reservoir
36 as represented by the dot-dash lines 36a. A service outlet is
indicated at 16_.
A chlorine tank 38 is operatively connected to a pump
40 in order to pump chlorine into reservoir 36. Additional
structural features of the present invention reside in the use of
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a backwash pump 42 which is connected via pipes 44 and 46 to
storage reservoir 36 and filter chamber 34, respectively.
Automatic valves 45 and 45_ and a filter valve 43 are arranged
for a typical backwash operation. A backwash drain is indicated
at 50 and a desludge auto valve is indicated at 52.
An additional feature of the present invention resides
in the attachment of a catwalk 54 which is secured to the unit at
one side thereof and incorporates a stairwell 56 for access
thereto. Catwalk 54 may employ a typical user supporting struc-
ture comprising a grate 54a.
OPERATION OF THE PACKAGE UNIT
With reference directed particularly to FIG. 2 of thedrawings J the operation of the package unit 10 of the present
invention will be more particularly described. The unit 10 is
designed to produce drinkable water from impure water and treat
sewage by removing sediment, color J bacteria and turbidity.
InitiallyJ raw water is introduced into mixing chamber 20 through
an appropriate influent water pipe 21 or the like. Chemical
coagulants are introduced through manifold 26 into mixing chamber
20 and the coagulants and water are chemically mixed due to the
turbulent action of the water and chemicals. The mixture passes
downwardly through mixing chamber 20 and into a upflow pipe 19
for eventual dispersion into coagulation chamber 22. Subsequently,
the mixture passes into chambers 22aJ 22b and 22c in a similar
manner following generally the directions indicated by arrows A.
It has been found that an appropriate residence time in each
chamber should be approximately 5 minutes. Pipes 19J l9a, l9b
and l9c are sized to regulate the intensity of the turbulence
which instigates and provides the mixing. The coagulant chemi-
cals form a floc which aids in the removal of colloidal and
suspended matter along with color, and phosphates and bacteria in .
the sewage treatment units. Additionally, the chemical coagulants
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also lower the pH of the water and a neutralizing agent may be
added as required in order to bring the mixture to a proper pH
for effective floc formation.
The next step involves the mixture being channeled
from coagulation chamber 22c through an opening 27 into primary
settling tank 28. Primary settling tank 28 is essentially an up-
flow clarifier which incorporates a generally V-shaped bottom
having sides 28a and 28b. The inclined settling surfaces allow
desludging from a single area while giving increased surface for
the light floculated solids to settle on. Thus, it may be
appreciated that the residence time necessary to separate effi-
ciently the floc from the water is substantially decreased.
Closely spaced side walls found in tube settlers are eliminated
in the primary settling tank 28. Desludging of primary settling
tank 28 occurs on a periodic basis by opening a valve at port 52
attached to a perforated manifold on the bottom of this chamber.
After the water has risen in primary settling tank 28 in the
direction of arrows B, the water flows over a launder 30 or wier
into a secondary settling tank 33. Secondary settling tank 33
also incorporates a generally V-shaped bottom having sides 33a
and 33b. The water flows upwardly in the direction of arrows C
through a plurality of tube settlers 32 which are inclined and
arranged coextensively and further incorporate a chevron cross-
sectional configuration. As shown in FIG. 3, tube settlers 43
are joined to form a plurality of connected passages, each indi-
vidual passage 32 having side walls 32b and chevron cross-
sectional walls 32c. The water then passes upwardly over another
wier 34a, and is dumped downwardly into a third settling tank or
filter 34 having a sand filter 34b.
After the water passes downwardly through sand filter
34b in the direction of arrows D and an underdrain assembly 35
(conveniently T-shaped), the water is discharged into the back-
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wash storage and chlorinated water reservoir 36. Chlorine may be
added to the water in reservoir 36 by means of chlorine pump 40.
Chlorine is applied to kill bacteria, most types of viruses
and to prevent the growth of slimes and algae. Reservoir 36 is
sized to maintain sufficient volume for backwash of filter 34b on
demand.
The desludging process takes place as follows. Desludg-
ing of chambers 33 and 34 occurs simultaneously. Backwash pump
42 pumps water from chamber 36 upwardly through sand filter 34b
thereby transporting solids over the top of weir 34a into chamber
33. This flow also removes sludge from the tube settlers 32, the
flow continuing to the bottom of chamber 33 whereupon it enters a
perforated manifold (not shown) for exit through port 50. Sludge
from the region around the perforated manifold is also removed.
While the invention has been particularly shown and
described with reference to the foregoing preferred embodiment,
it will be understood by those skilled in the art that other
changes in form and detail may be made therein without departing
from the spirit and scope of the invention as defined in the
2Q appended claims. For instance, the present invention could
readily be used as a sewage or industrial treatment plant as well
as a plant for producing drinkable water.
