Improvements in Precipitation Tanks, and in Means for Delivering Water to Filter Beds, for the Purification of Sewage and Impure Waters.
Year: 1894

page_text: Date of Application, 2nd May, 1894
Complete Specification Left, 2nd Mar., 1895-Accepted, 27th Apr., 1895
Improvements in Precipitation Tanks, and in Means for Delivering
Water to Filter Beds, for the Purification of Sewage and Impure
Waters.
I, FRANK PULLEN CANDY of 56 Nightingale Lane Balham in the County of
Surrey Sanitary Engineer do hereby declare the nature of this invention to be as
follows:-
The first part of my invention relates to improvements in precipitation tanks
and refers specially to what are known as "upward flow tanks."
I cause the sewage to enter the precipitation tank at the required depth, and
preferably from the side of the tank, at one or more points in such manner and at
such an angle that a rotating or the like motion of the sewage is set up in the tank
whereby the flow of the sewage is equalised and divided over the whole of the
tank as much as possible.
My invention consists further in improvements in the spreading and equalisition
of the flow of water upon the top of filter beds and relates to those filters which are
not worked waterlogged or full of water but which are worked with the outlet at
the bottom of the filter passing as much and capable of passing more water than is
being run on the top of the filter, or in other words my said invention relates to
filters in which the interstices between the grains or granules of a part or all of the
filtering medium are not wholly filled with water, but which contain air, or oxygen,
or other gas. I will speak of these two classes of filters as waterlogged filters and
aerating filters, my said improvements relating to the latter.
In aerating filters as at present constructed the top layer of material has to be
of considerable fineness having to serve as the means of spreading the water over
the surface of the filter bed, it is thus liable to become rapidly choked up by
suspended matter in or derived from the water which is being filtered, a further
drawback has hitherto been that when the top layer of material is freshly clean or
washed, the water to be filtered passes through the bed too rapidly and generally
through only a part of the area of the bed so that one part of the bed is doing too
much work and another part of the bed is doing no work at all.
According to my invention I shower the water from an overflowing conduit or
conduits, placed above the surface of the bed, upon a spreader or spreaders also
placed above the surface of the bed and from the said spreader or spreaders the
water is distributed upon the filter bed, or I employ other like means.
Or I shower the water upon the bed by one or more perforated pipes or the like
placed above the surface of the filter bed and pivoted upon a centre through which
the water to be filtered is admitted to the perforated pipe or pipes or the like they
being revolved by any suitable means, or in lieu of the said revolving pipe I
sometimes employ a travelling perforated pipe or pipes or the like through which
the water is delivered on to the filter bed the said travelling pipe or pipes or the
like being moved by any suitable means, or I sometimes employ a rotating spreader
similar to those used on water carts, or I break the water into drops or spray by
means of a current or blast of air or steam or the like and cause the broken up
water to shower upon the filter bed; or I employ other similarly suitable means.
I sometimes attach "
"
roses or perforated spreaders to the perforations in any of
the beforementioned delivery conduits. I sometimes and especially in the case of

page_text: the revolving or travelling spreading arrangement aforesaid, when filtering sewage
water, do not precipitate the sewage with chemicals but simply allow it to settle or
deposit by gravitation before the sewage water is run on the filter.
Dated this 30th day of Anril 180A
Improvements in Precipitation Tanks, and in Means for Delivering
Water to Filter Beds, for the Purification of Sewage and Impure
Waters.
I FRANK PULLEN CANDY of 56 Nightingale Lane Balham in the County of
Surrey Sanitary Engineer 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 :-
My invention consists in part of the improvements hereinafter described in
precipitation tanks of the kind known as upward flow tanks. According to my
said improvements I arrange for inlet of the liquid to be precipitated to the
precipitation tank at the required depth preferably from the side of the tank at
one point or two or more points in such manner and at such an angle that rotatory
motion of the liquid in the tank is produced and the entering liquid is diffused
throughout the body of liquid in the tank at or about the level of the inlet
or inlets.
My said improvements are illustrated in Figures 1, 2, 3, 4, 5 and 6 of the
accompanying drawings Figure 1 being a plan and Figure 2 a vertical section of a
tank provided with one side inlet and Figures 3 and 4 like views of a tank provided
with a number of side inlets and Figures 5 and 6 like views of a tank provided
with inlets arranged within it.
In each of the said figures the wall of the tank is marked a the conduit by which
liquid is conveyed to the tank is marked 6 and the arrangements for conveying
liquid from the tank consist in each case of troughs cc which open at one end into
a channel d formed on the outside of the tank at its upper part.
In the arrangement shown in Figures 1 and 2 the inlet consists of a passage e
(which may be formed of pipes as illustrated in Figure 4) communicating at its
upper end with the conduit band at its lower end with the lower part of the
interior of the tank the discharge end of the said passage being so formed or
situated at such an angle relatively to the tank as to cause the stream of liquid
passing from it to enter the tank horizontally in such a direction that rotatory
motion of the liquid is produced by the passage of the entering liquid into that in
the tank which motion produces diffusion of the said entering liquid throughout the
body of liquid in the tank at or about the level of entry.
In the arrangement shown in Figures 3 and 4 the conduit 6 communicates with a
channel formed around the upper part of the tank and the passages by which the
liquid is conveyed to the tank consist of pipes 9 g communicating at their upper
ends with the said channel f and at their lower ends with the lower part of the
interior of the tank. As shown in the drawings the discharge ends of the
pipes 99 are formed and arranged similarly to the discharge end of the passage e
hereinbefore described with reference to Figures 1 and 2 that is to say the said
ends of the said pipes are so arranged as to cause the liquid passing through them
to enter that in the tank in horizontal or nearly horizontal streams and at such
angles as to produce rotatory motion of the liquid in the tank at or about the level
of entry of the said streams.
In the arrangement illustrated in Figures 5 and 6 the inlet of the tank consists
of a pipe i communicating with the conduit b and connected at its lower end to a

page_text: box provided with discharge pipes so formed as to cause liquid passing
therefrom into a body of liquid in the tank to be diffused in the said body of liquid
substantially as hereinbefore described with reference to Figures 1 to 4. The said
pipei is supported in the required position by means of a metal band / bolted at its
ends to a girder m placed across the tank.
"7
My invention consists further in the combination with aërating filters of the
apparatus hereinafter described for distributing water onto the beds of such filters.
The filters which I term "aërating filters are those which are not worked
waterlogged or full of water but which are so worked that the interstices between
the grains or granules of a part or all of the filtering medium are partially
occupied by air or oxygen or other gas while the water being filtered is passing
through them.
In aerating filters as heretofore supplied with water it is necessary that the top
layer of filtering material be of considerable fineness the said layer having to serve
as the means of spreading the water over the surface of the filter bed consequently
the said top layer is liable to become rapidly choked by suspended matter in or
derived from the water which is being filtered. A further drawback has hitherto
been that when the top layer of filtering material is freshly cleaned or washed the
water to be filtered passes through the bed too rapidly and generally through only
a part of the area of the bed so that one part of the bed is doing too much work
and another part of the bed is doing none.
According to my said improvements I provide for the spreading or distribution
of water over the surface of aërating filter beds by means of the arrangements and
apparatus hereinafter described and I do not rely upon the fineness of the top
layer of the filter bed or upon the partial choking of the same to accomplish the
spreading or distribution of the water thereon.
One form of apparatus which I use for the said purpose is illustrated in section
in Figure 7 of the accompanying drawings. The said apparatus consists of a
conduit n supported in any suitable manner above the surface of the filter bed o
and having spreaders p p mounted between it and the said surface which spreaders
may be suspended from the conduit n by means of rods gq as shown or they may
be otherwise supported. The water to be filtered is supplied to the conduit n from
which it overflows the overflow falling onto the spreaders p q which break it up
and cause it to fall in showers and thus distribute it over the surface of the
filter bed.
Another form of apparatus for the said purpose consists of a perforated pipe
mounted above the filter bed and connected to the water supply and capable of
being caused to rotate the water issuing from the said perforations being scattered
over the filter bed by the rotation of the said pipe. This apparatus is illustrated
in elevation in Figure 8 of the accompanying drawings and a portion thereof is
illustrated in section in Figure 9. Referring to the said figures r is the perforated
pipe which is provided at its ends with spindles the spindle being supported
by a plummer blocks and carrying a band pulley and the spindle working in a
stuffing box formed in a pipe t by which water is conducted to the apparatus.
Leakage between the pipes r t may be prevented by means of capped leather
packing secured between the outer side of the piper and the inner face of the
pipe t as shown in the section Figure 9.
Another form of apparatus for distributing water upon filter beds is illustrated
in Figure 10 of the accompanying drawings. This apparatus which is especially
suitable for circular filters consists of a perforated pipe u mounted above the
surface of the filter bed and capable of being rotated by means of a worm and
worm wheel and winch v' to which pipe u the water to be fitered is conveyed by
means of a stationary pipe u¹ supported by a pillar u³ the part of the said pipe u¹
adjoining the pipe u being provided with a faced pivot joint. When water is being
supplied to the filter the pipe u is caused to rotate by turning the winch v¹. In
place of the worm wheel and winch illustrated in the drawing any other convenient
arrangement for causing rotation of the pipe u may be used.

page_text: Another form of water distributing apparatus for aërating filters is illustrated in
Figure 11 of the accompanying drawings. This apparatus consists of a perforated
pipe to supported by wheels w¹ to resting on the sides of a trough mounted above
the filter bed and extending along its whole length into which trough a branch 10
on the pipe to dips. The water to be filtered is supplied to the trough and is
caused to pass therefrom into the pipe to and to issue from the perforations in the
said pipe by syphon action. While the water is so passing the pipe w is drawn
backward and forward along the trough by any convenient means the water being
thus distributed over the filter bed. For convenience in starting the syphon action
of the pipe to it is furnished with valves to to and a funnel mouthed tube 10*
provided with a stop cock w' and the branch w² of the said pipe to is furnished at
its lower end with a stop valve 10 worked by means of a rod to carrying
handle and screwed at its upper end the screwed part engaging with a screw
box supported above the pipe to as shown. In order to start the syphon action
the valves to and we are closed and the cock to is opened and water is poured
into the funnel of until the branch pipe wo and the portions of the pipe w above
the valves ww are filled. On the cock to being then closed and the valves 10³ 10³
and to opened the water in the trough flows therefrom into the pipe to and issues
through the perforations therein. To provide for escape of air from the parts of
the pipe below the valves small holes are made in the upper part of the said
pipe at distances of about six or eight feet apart and fitted with stop cocks which
are opened when water is first admitted to the pipe w and are closed when the air
has escaped from the said pipe. In consequence of the small scale of the drawing
the said stopcocks are not shown therein.
=
Another form of apparatus which I combine with aërating filters for distributing
water over the beds of such filters is somewhat similar to the water distributing
apparatus carried by some road watering carts. The said apparatus which is
illustrated in elevation in Figure 12 and in plan in Figure 13 consists of a rotatory
shaft y provided with a chain wheel or pulley y or other convenient means for
imparting rotatory motion to it and mounted in bearings y' y² above the filter bed
and carrying a plate z having radial ribs ¹ z' on its upper face onto which plate
a stream of the water to be supplied to the filter is delivered from a shoot or pipe
or other suitable conduit not shown in the drawings. In using this apparatus the
shaft y is caused to rotate while water is being delivered onto the disc z the effect
being to project the water by centrifugal force over the surface of the filter bed in
the form of a shower. The plate z may be of the form of a flat disc as illustrated
in Figure 12 or it may be of conical form as illustrated in Figure 14. Or portions
of the said plate may be of the form of portions of a flat disc and others of the
form of portions of a cone.
The perforated pipes u and w may be provided with roses or perforated spreaders
similar to those used with ordinary garden watering-pots.
The beds of aërating filters provided with water distributing apparatus of the
kind hereinbefore described may consist of material of any degree of coarseness.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that I claim :-
First. The provision for inflow of liquid to an upward flow precipitation tank
by means of an inlet or inlets constructed and arranged substantially as herein-
before described and illustrated in Figures 1, 2, 3, 4, 5 and 6 of the accompanying
drawings that is to say, the construction and arrangement of the said inlet or inlets
in such a manner that the stream or streams of liquid passing therefrom enter the
liquid in the tank horizontally or nearly horizontally and at such angle or angles
that rotation of the body of liquid in the tank at or about the level of the said
inlet or inlets is produced by the inflowing liquid.
Secondly. The combination with a filter of arrangements substantially as herein-
before described and illustrated in Figure 7 of the accompanying drawings for
causing distribution of the water to be filtered over the surface of the filter bed..

page_text: Thirdly. The combination with a filter of apparatus whereby water to be
filtered is delivered in small streams or in drops onto the surface of the filter bed
the said apparatus being so constructed and arranged or mounted that the part
from which the water is delivered is capable of being rotated or moved over or
above the said bed for the purpose of distributing the water thereon.
Fourthly. The combination with a filter of apparatus constructed and acting
substantially as bereinbefore described with reference to Figure 8 of the
accompanying drawings for distributing water to be filtered over the surface of
the filter bed.
Fifthly. The combination with a filter of apparatus constructed and acting
substantially as hereinbefore described with reference to Figure 10 of the
accompanying drawings for distributing water to be filtered over the surface of
the filter bed.
Sixthly. The combination with a filter of apparatus constructed substantially
as hereinbefore described with reference to Figure 11 of the accompanying
drawings for distributing water to be filtered over the surface of the filter bed.
Seventhly. The combination with a filter of apparatus constructed substantially
as hereinbefore described with reference to Figures 12, 13 and 14 of the
accompanying drawings for distributing water to be filtered over the surface of
the filter bed.
Dated the First day of March 1895.
W. T. WHITEMAN,
Agent for the Applicant.