An Improved Method of, and Apparatus for Filtering Water.
Year: 1898

page_text: Date of Application, 24th May, 1898-Accepted, 9th July, 1898
COMPLETE SPECIFICATION.
An Improved Method of, and Apparatus for Filtering Water.
We, OMAR HESTREN JEWELL and. WILLIAM MARSHALL JEWELL, both of 73-75,
West Jackson Boulevard, Chicago, Cook County, Illinois, United States of America,
Inventors, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
Our invention relates to the filtration of water in large quantities, for potable and
other purposes. Where large quantities of water are to be filtered, it is the common
practice to employ filters consisting of a suitable tank which contains a filter bed of
sand or other suitable granular material, the water to be filtered being discharged
upon the filter bed, through which it percolates, and is carried off through a pure-
water outlet-pipe, a series of strainers in the bottom of the filter bed serving to
prevent the sand from entering the pure-water pipe. In filters of this type a
coagulating agent, such as alum, is usually employed, which is introduced into the
water before it passes through the filter bed, for the purpose of coagulating the
impurities therein contained, so that they may be more readily retained in the filter
bed. In some cases a settling chamber has been provided under the filter tank, to
permit the heavier coagulated impurities to settle out of the water before it passes
into the filter tank, thereby relieving the bed of a large part of the impurities which
would otherwise be retained in it. Even where a settling chamber is provided, in a
comparatively short time the filter bed becomes foul, and is clogged to a great
extent by the impurities which accumulate in it, so that filtration is impeded and
the capacity of the filter greatly reduced. It then becomes necessary to wash the
bed, and this is accomplished by reversing the flow of water, causing it to enter the
filter bed from below, and pass out from above, the rising water loosening the filter
bed and carrying off the impurities accumulated in it. To further promote the
washing of the bed, agitators have been provided, which are caused to move
through the filter bed during the operation of washing, so that the bed is thoroughly
cleansed.
Our invention relates to filters of the type above described, and has for its
object to provide certain improvements in the method of filtration by the use of granular
filters, and also to provide a filter of improved construction. To this end it
consists :-
1. In effecting a condensation or compacting of the granular particles composing
the filter bed, which is greatest at the bottom of the bed and diminishes toward the
surface thereof, so that, while the less compact upper part of the bed suffices to
remove the impurities of greater bulk, the finer impurities are removed by the
passage of the water through the lower part of the bed, owing to its more compact
state. A further advantage of this method of filtration is that the accumulation of
the impurities in a layer at or near the top of the bed, which has resulted from
methods heretofore employed, is avoided, the impurities, by our improved method,
being distributed throughout the entire filter bed. The efficiency of the filter, there-
fore, does not rapidly diminish, so that less frequent washings are necessary. Our
improved method further consists in applying suction to the bed and water process

page_text: of filtration, by which the bed is not only compacted, but also an accumulation of air
is secured at the bottom of the filter bed, which, when the current is reversed for
washing purposes, rises through the bed and greatly facilitates the agitation thereof
the suction also serving to promote the flow of the water through the bed.
2. In an improved method of coagulating and separating the impurities before the
water enters the filter tank; said method consisting in introducing a coagulant into
the water, either before or while it is in the settling chamber, and imparting to the
water a gentle circulatory movement, by which a large part of the impurities are
caused to coagulate or flocculate, and then settle to the bottom of the settling
chamber; so that the water which enters the filter bed is comparatively pure, thus
reducing the work to be performed by the bed, and enabling it to be used much
longer than heretofore without washing.
3. In an improved construction of filter by which the methods above described
may be effectually applied; said filter consisting, generally, of a filter tank adapted
to, contain a bed of granular material; a settling chamber arranged below the filter
tank; an inlet pipe adapted to conduct unfiltered water into the settling chamber,
and to discharge it tangentially thereinto, so as to impart to it a circulatory move-
ment; a pipe or passage adapted to permit the unfiltered water to pass into the filter
tank above the filter bed; a pure-water pipe having strainers opening into the lower
portion of the filter tank, said pure-water pipe having a trap by which the admission
of air is prevented and suction applied to the filter bed and water, for the purpose
above stated; and connections whereby the flow of water through the filter tank may
be reversed.
4. In an improved strainer, or strainer head, through which the water enters the
pure-water pipe from the filter tank, and, when the current is reversed, flows from
the pure-water pipe into the filter tank; such strainer head being so constructed
that, in washing, the wash water is distributed in all directions through the filter
bed, thereby promoting the agitation thereof, and, in filtering, the filtered water can
gain access to the strainer from all sides, as well as from above, promoting the
outflow thereof. Our improved construction further provides for lateral or inclined
water-passages in the strainer heads, so that such perforations are relieved from the
weight of the filter bed, permitting the water to pass more readily through the
strainers into the pure-water pipe.
5. In a controller for controlling the flow of the water through the filter tank,
so that the quantity which passes through it in any given time may be accurately
regulated.
6. In improved agitating devices by which, in washing, the bed may be effectually
agitated, and, in filtering, the surface of the bed may be gently raked or scratched at
convenient intervals, to break up only the upper crust after filtration has been in
progress for a considerable time, thereby permitting the passage of the water through
the bed. In filters in which suction is not employed to maintain the compactness of
the bed, as above described, it is impracticable to agitate even the surface of the bed
during filtration, as, when the crust is broken, the water passes through the bed
quickly, and with a removal of a part only of the impurities. Our improved agitators,
therefore, are designed for use only in filters adapted to apply our improved process
for compacting the filter bed, above described.
7. In so proportioning the area of the pure-water pipe, in cross section, with
reference to the combined areas of the strainer passages, that the combined areas of
the passages at the different strainers will be equal to the area, in cross section, of
the pure-water pipe, thus providing for a uniform distribution of the wash water, in
washing, throughout, the filter bed, and for a uniform application of the suction of
the different parts of the bed.
Our invention further embodies certain details of improvement which will be
hereinafter pointed out.
In the accompanying drawings,
Figure 1 is a vertical section of our improved filter;

page_text: Figure 5 is a side view of one of the distributing pipes in the filter tank, showing
the strainers;
Figure 6 is a plan view of the same;
Figure 7 is a plan view of the filter;
Figure 8 is a side view of one of the agitator arms, with its support;
Figure 9 is a view of the same in a different position;
Figure 10 is a view of one of the collars which secure the agitator arms on the
supporting shaft;
Figure 11 is a top view of a part of the supporting shaft, showing the position of
one of the agitator arms and its collars;
Figure 12 is a vertical section of the controller;
Figures 13 and 14 are sections of a tank, showing the granular matter in different
states of compactness;
Figures 15, 16, 17 and 18 are magnified views, illustrating how the granular
matter is compacted by the down-draft or suction.
20 Figure indicates a tank, preferably of sheet iron, which has a bottom 21, and
contains a filter tank composed of a bottom 22 and side wall 23. The filter tank is
adapted to contain a bed of sand, or other granular material. The external tank 20
and the filter tank are preferably cylindrical in form, but they may be made of other
shapes. The filter tank may be supported at any convenient point above the
bottom of the tank 20, upon suitable pillars 24. It is of somewhat less diameter
than the internal diameter of the tank 20, forming a channel 25 between them.
A plate 26 is fitted between the filter tank and the wall of the tank 20, and forms
a bottom for the space 25. The plate 26 is arranged near the level of the bottom 22
of the filter tank, as shown in Figure 1. It will be noted also that the wall 23 of
the filter tank does not extend to the upper edge of the outer tauk 20. 27
indicates a valved inlet-pipe which communicates with the bottom of the cylindrical
space of the chamber 25, and serves to carry off the overflow, as will be hereinafter
described. The valve 28 of the pipe 27 is shown in Figure 1. By supporting the
filter tank in the manner described, a settling chamber 29 is formed under it, in
the outer tank 20. The settling chamber 29 communicates with the upper portion
of the filter tank by a pipe 30, which extends through the bottom 22 of the filter
tank to a point slightly above the upper edge of the side wall 23 of said tank (see
Figure 1. The lower end of the pipe 30 carries an elbow 31 having a series of
nozzles 32 for discharging of water. The arrangement is such that unfiltered
water may rise through the elbow 31 and pipe 30 into the upper portion of the
filter tank, being discharged upon the top of the filter bed therein, or, when desired,
the water in the filter tank may be caused to discharge through the pipe 30, elbow 31
and nozzles 32, into the settling chamber 29, being directed against the different
parts of said tank from said nozzles, which are adjusted to discharge in different
directions, as shown. The elbow 31 is also arranged to be rotated to discharge water
in different directions, by means of a shaft 33, which rises through the pipe 30 and
is secured at its lower end to the elbow 31, and carries at its upper end a gear
wheel 34 driven through a spur gear 35 and bevelled gears 36-37, pulley 38, said
pulley being driven from any suitable source of power. 39 indicates a cross beam
secured at the top of the outer tank, which beam carries a suitable bearing for the
upper end of the shaft 33.
Water is admitted to the settling chamber 29 through an inlet pipe 40 having a
valve 41, said pipe being arranged to discharge into the lower portion of the settling
chamber, as shown in Figure 1, and having a nozzle 42, which is adjusted to discharge
water substantially tangentially into the settling chamber, thereby imparting to the
water a circulatory movement. The inlet pipe 40 is also provided with a valved
lever 43, (Figures 1 and 2), which is connected to a suitable check valve in the pipe,
and is operated through a connecting rod 44 and lever 45, from a float 46 which is
mounted in a chamber 47 arranged near the upper portion of the outer tank, as shown

page_text: in Figure 1. The chamber 47 communicates, by a passage 48, with the interior of
the filter above the partition plate 26. The arrangement is such that, when the
water rises to a certain point in the filter tank, the rising of the float, thereby effected,
will rock the lever 43 in such manner as to shut off the inflow of water.
connecting rod 44 is provided with a number of adjusting holes, so that the action of
the float may be adjusted as desired.
The
49 indicates the pure-water pipe, which is connected, by one or more risers 50, to
a manifold 51 arranged in the filter tank, upon the bottom thereof, as shown in
Figures 1 and 3. The manifold 51 has a series of branch pipes 52, and said branch
pipes carry strainers 53, as shown in Figures 3, 4 and 5. The strainers 53 are
constructed as illustrated in Figure 4; being provided with a base 55, a stem 56 by
which they may be secured in place, said stem being preferably screw threaded, and
a cap 57, which, as shown in Figure 4, is substantially M-shaped in cross section,
having a depressed centre 58, which is arranged opposite an inlet passage 59. The
centre 58 of the strainer is imperforate, and thickened somewhat, forming a deflector
to direct the upwardly-flowing wash-water toward the periphery of the strainer.
The strainers are provided with curved, or inverted-V-shaped, slits 60 in. their
convex portions, as shown in Figure 4, so that in filtering water may flow into
the strainers from the sides and in washing it may be discharged laterally.
Furthermore, by this construction, the weight of the filter bed, as will hereinafter
appear, is supported upon the top of the strainer heads, relieving the inclined
portions of the passages from the weight, to a considerable extent, and facilitating
the admission of water thereto. As illustrated in Figure 1, the pure-water pipe 49 is
provided with a trap 61, placed a considerable distance below the filter tank. The
trap 61 serves to prevent the admission of air into the pipe 49 and
risers 50.
62 Figures 1 and 12 indicates a controller, which is connected to the pure-
water pipe at any convenient point, and serves to regulate the flow of water from
the filter.
The controller 62 is illustrated in Figure 12, from which it will be seen that
it consists of a butterfly-valve 63, suitably pivoted in the pipe and connected by a
rod 64 to a perforated piston 65 which moves vertically in the pipe. The piston 65
carries a stem 66 moving in a suitable bearing 67 carried by a screw cap 68 fitted in
the upper end of the pipe. The arrangement is such that when the piston 65 moves
vertically it will rock the valve 63. The controller is operated by the friction of the
liquid passing through the openings in the piston 65. The adjustment being such
that the friction of the flowing liquid through the piston is equal to the weight of
the piston, said piston will remain stationary, as the valve 63 is balanced. If, however,
the pressure of the liquid in the pipe below the piston increases, the friction of the
liquid passing through the perforations in the piston head will be increased, causing
the piston to rise, and closing the valve 63. The piston will continue its upward
inovement until the valve has been closed sufficiently to reduce the pressure upon
the piston to a point where the friction will again equal the weight of the piston; the
result being that the flow of liquid is at all times maintained at a constant
rate.
69 indicates a wash water pipe, which communicates with the pure water pipe 49,
and is provided with a valve 70 71 indicates a valve for the pure water pipe, by which
the controller 62 may be cut off. 72 indicates a third valve, in a pipe 73 which
communicates with the pipe 49, and is used to discharge impure water into the
sewer. 74 indicates a wash water inlet in the bottom of the settling chamber 29,
and 75 (see Figure 3) a valve therefor.
The agitation of the filter bed is accomplished by means of a series of agitator
arms 76, said arms being carried by shafts 77 78-79 secured to a cross head 80
carried at the upper portion of the shaft 33, and adapted to rotate therewith (see
Figures 1 and 7). The shafts 77 78 project from the ends of the cross head 80
toward the wall 23 of the filter tank, and the shaft 79 extends at right angles to
the cross head 80, as shown in Figure 7. As shown in the drawings, each of the

page_text: shafts 77-78-79 carries a plurality of agitator arms 76, which arms are pivoted
upon their respective shafts by means of blocks 81, which are pivoted upon the shaft
and have suitable sockets in which the upper ends of the agitator arms are secured.,
Set screws 82 are provided, which secure the agitator arms to the blocks and permit
their adjustment vertically. Each block is secured between a pair of collars 83-84
which are secured upon the shafts 77-78-79, as shown in Figure 7, and are secured
in place by set screws 85. The arins 76 are arranged to be held in a substantially
vertical position when the shaft 33 rotates in one direction, and to swing back to the
position shown in Figure 9 when said shafts rotates in the opposite direction; and
to secure this action each of the blocks 81 is provided with a segmental block 86 at
each side, and the collars 83-31 are provided with segmental blocks 87-88,
which are adapted to coact with said blocks 86 to limit the movement of the arms 76.
For example, when the agitator arins 76 are in a vertical position, as shown in
Figures 8 and 11, the blocks 86 are in contact with the blocks 87-88, preventing
the arms 76 from moving to the left, but permitting them to move to the right. By
this construction, when the shaft 33 is rotated in the direction indicated by the arrow
in Figure 7 the arms 76 may swing to an inclined position, as shown in Figure 9; but
when the shaft is rotated in the opposite direction, the arms 76 being carried in the
direction indicated by the arrow in Figure 8, they are retained in a vertical position.
Therefore, by rotating the shaft 33 in one direction, the agitator arins may be
retained in position to penetrate deeply into the filter bed, and agitate it, whereas,
when the shaft is rotated in the opposite direction the resistance of the bed causes
the arms to assume an inclined position, their ends resting practically upon the
surface of the filter bed, and they may therefore be so rotated without agitating the
bed materially. For the purpose of scraping the bed slightly when the arms are in
the latter position, they are provided with flexible devices, such as chains, 89; at
their lower ends, which are adapted to be drawn over the upper surface of the bed,
and serve to scratch or rake the crust which ordinarily forms there, without agitating
the bed sufficiently to interfere with filtration. As shown in Figure 1, the agitator
arms 76 which lie near the centre are shorter than the others, in order that they
may scrape that portion of the bed nearest the centre.
Having described the construction of our improved filtering apparatus, we will now
explain some of the features of its operation which have not already been pointed
out specifically.
In operation, the unfiltered water, into which a coagulant has been introduced, is
admitted into the settling chamber 29 through the nozzle 42 of the inlet pipe 40,
and, as already explained, is given a circulatory or whirling movement, owing to, the
manner of its discharge. Such whirling effects the coagulation and sedimentation of.
a large portion of the impurities, which remain in the settling chamber, the water
rising through the elbow 31 and pipe 30 to the upper portion of the filter tank, where
it is discharged upon the filter bed. The water then passes down through the filter
bed to the strainers, through which it flows into the inanifold 51, and thence to the
risers 50 and pure-water pipe 49. The first water after washing is. discharged into
the sewer through pipe 73, but as soon as the water runs pure the valve 72 is closed
and the valve 71 opened, permitting the pure water to flow through the trap 61 and
controller 62. The operation of the controller has already been described. The head
of water in the risers 50 creates a partial vacuum within the filter bed, the vacuum
being greatest in the lowest portion of the bed, and gradually diminishing toward
the upper surface thereof. By this means a continuous suction is exerted, which is
greatest in the lower portion of the bed, compacting it so that its density is greatest
at the bottom and gradually diminishes toward its upper surface. The condition of
the filter bed at this time is illustrated in Figure 13. Furthermore, the suction
causes the air contained in the water in the filter to separate, and concentrates it, the
minute bubbles coming together forming larger bodies of air, which are, to a great
5 extent, retained in the filter bed. As the fine air-bubbles converge they act to con-
centrate and coagulate the particles of suspended matter, so that finally the larger

page_text: masses of impurities thus formed are easily intercepted and retained by the filtering
material. As the process of filtration continues, the air extracted from the water
gradually accumulates in the bed, still further compacting it, and thereby increasing
the efficiency of the filter to such an extent that, even after the filter bed contains
large quantities of impure matter, the filter may nevertheless be continued in use
with satisfactory results, thus making it unnecessary to wash the bed as frequently
as has been necessary with other forms of ilters employing granular filter beds. The
condition of the filter bed after filtration has continued for a short time is illustrated
in Figure 14. Figures 15, 16, 17 and 18 illustrates different stages of the con-
centration of the impure particles and air bubbles contained in the water.
Where this process is employed the use of a coagulent is not so essential as in
other methods of filtration, and consequently a much smaller quantity of the
coagulent may be used.
When the filter bed becomes so impure that it does not give satisfactory results,
the valve 71 is closed, and the valve 70, which communicates with the unfiltered
water supply, is opened, thereby permitting unfiltered water to enter through the
pure-water pipe 49 and strainers into the bottom of the filter tank. The vacuum is
therefore destroyed and the air bubbles liberated, so that they rise through the bed
agitating it and promoting the carrying off of the impurities accumulated therein.
At the same time, the distribution of the wash water throughout the bed is made
more efficient by the construction of the strainers, as above described, and the uniform
distribution of the water throughout the bed effected by making the combined area
of the passages 59 of the strainers, in cross section, substantially equal to that of the
'cross-sectional area of the pure-water pipe 49. During the operation of washing, the
agitators are caused to rotate in the direction opposite to that indicated by the arrow
in Figure 7, further agitating the bed, as already described. The wash water, rising
through the filter bed, overflows the filter tank and passes into the annular
chamber 25, and thence out through pipe 27, the valve 28 having been opened.
After the washing has been completed the agitators are stopped and the valves 28
and 70 closed. The valves 72 and 41 are then opened, the latter having been closed
before the operation of washing commenced, and the operation of filtering resumed.
After the filter has been in operation a greater or less time, depending upon the nature
of the water under treatment, in order to promote filtration without stopping to wash
the filter bed, the agitators may be caused to rotate in the direction indicated by the
arrow in Figure 7, carrying the arms 76 in an inclined position around the tank, and
raking or scraping the upper surface of the bed sufficiently to break up the crust
which forms thereon. This does not interfere with filtration, however, because the
filter bed is maintained in a compact condition by the suction of the down draft.
When it is desired to wash the settling chamber 29, this may be effected at the
time of washing the filter bed by keeping the valve 28 closed, causing the wash water
to rise high enough in the filter tank to overflow into the pipe 30, and be discharged
through such pipe and the elbow 31 into the settling chamber. By then rotating the
elbow 31, as already described, the water may be directed to the different parts of the
settling chamber, thoroughly washing it out, the impure wash-water being discharged
through the passage 74, the valve 75 having been opened for that purpose.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. The system of filtration substantially as herein shown and described.
2. The method of purifying water which consists in subjecting the water con-
taining impurities to suction while passing through a granular filter-bed, substantially
as described.
3. The method of purifying water which consists in passing it through a granular
filter-bed of gradually increasing density, meanwhile subjecting the water to the
influence of a gradually increasing suction, substantially as described.

page_text: 4. The method of purifying water for potable purposes, which consists in adding
a suitable coagulating re-agent, and imparting to the water a circulatory movement,
substantially as described.
5. The method of purifying water for potable purposes, which consists in adding a
suitable coagulating re-agent, imparting to the water a circulatory movement, and
afterwards subjecting the supernatant water to filtration, substantially as described.
6. In a filter, the combination of a filtering apparatus, a settling chamber adapted
to receive the water before filtration, and means for gently agitating the water in the
settling chamber, substantially as described.
7. In a filter, the combination of a filtering apparatus, a settling chamber adapted
to receive the water before filtration, and an inlet pipe arranged to discharge the
inflowing water into the settling chamber substantially tangentially, substantially as
described.
8. A filter consisting of a filter tank, a pure-water pipe communicating with the
lower portion thereof, and a granular filter-bed in said tank, the lower portion of said
filter bed being compacted more closely than the upper portion thereof, substantially
as described.
9. A filter consisting of a filter tank, a pure-water pipe communicating with the
lower portion thereof, a granular filter-bed in said tank, the lower portion of said
filter bed being compacted more closely than the upper portion thereof, means for
maintaining a partial vacuum in said filter bed during filtration, and means for
reversing the flow of water through said filter bed, substantially as described.
10. A filter consisting of a filter tank, a pure-water pipe communicating with the
lower portion thereof, a granular filter-bed in said tank, means for maintaining a
partial vacuum in said filter bed during filtration, and agitators adapted to agitate
the upper portion of the bed, substantially as described.
11. In a filter, the combination of a water pipe, a series of strainers communicating
therewith, each of said strainers consisting of a perforated head and a supporting
base having a passage for the inflow and outflow of water, the combined area of said
passages, in cross section, being substantially equal to the cross-sectional area of the
water pipe, substantially as described.
12. A strainer for filters, consisting of a base having an inlet, and a head secured
thereupon, said head having a plurality of slits arranged in circular form, substantially
as described.
13. A strainer for filters, consisting of a base having an inlet, a head thereupon,
said head having a plurality of slits arranged in circular form, and a central deflector
over the inlet, substantially as described.
14. A strainer for filters having perforations arranged to discharge water in a lateral
direction, substantially as described.
15. A strainer for filters, having substantially inverted V-shaped orifices,
substantially as described.
16. The combination of a filter tank, a water pipe, and a series of strainers com-
municating with said water pipe, each of said strainers having perforations arranged to
discharge water laterally, substantially as described.
17. A controller consisting of a suitable casing, a piston therein constricting the
fluid passage, and a butterfly valve controlling the fluid passage and adapted to be
operated by the movement of said piston, substantially as described.
18. A controller consisting of a pipe, a perforated piston adapted to reciprocate
therein, and a balanced butterfly-valve controlling the fluid passage and connected at
one side of its pivot to and operated by said piston, substantially as described.
19. A filter having inlet and outlet water pipes, and a controller located in one of
said pipes controlling the flow of water through the filter, substantially as described.
20. The combination of a filter tank adapted to contain a granular filter-bed, means
for washing said tank, and rotary agitators for agitating said filter bed, said agitators
having chains at their lower ends adapted to scratch the upper surface of the bed,
substantially as described.

page_text: 21. The combination of a filter tank, a series of agitator arms which penetrate the
filter bed, means for revolving said agitators in the filter tank, and means for holding
said arms in a vertical position when moved in one direction, and for permitting them
to assume an inclined position when moved in the opposite direction, substantially as
described.
22. The arrangement of the filter tank and agitators substantially as herein shown
and described.
23. The arrangement of a settling chamber, a filter tank above the settling chamber,
and means for washing the settling chamber, substantially as herein shown and
described.