Improvements in Apparatus for Filtering Water.
Year: 1898

page_text: Date of Application, 14th May, 1898-Accepted, 6th Aug., 1898
COMPLETE SPECIFICATION.
Improvements in Apparatus for Filtering Water.
I, ARMAND PUECH, of Mazamet (Tarn), in the Republic of France, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to improvements in apparatus for filtering large volumes
of water.
Filters for large volumes of water to be used for industrial purposes or for
supplying towns require very large surfaces both in the case of decanting appara-
tus and in sand filters. Furthermore, they become dirty very quickly as they
admit impure water at once over the whole filtering layer or medium.
Now, it is the object of this invention to obviate these two serious disadvantages
and to this end I construct filtering apparatus, which has a large output (25 to
100 cubic metres per square metre), and the object of which is to free the impure
water in a systematical manner of the whole or the major portion of the organic
or inorganic impurities which it holds in suspension.
The final filters for drinking water, which have an output of scarcely 3 to 5
cubic metres per square metre, will have their output increased to the maximum,
whilst at the same time purifying in a manner more practical, more durable, more
rapid and considerably less costly than heretofore. If their dimensions be re-
tained they can be provided with finer filtering materials or media than hereto-
fore; quartz, broken coal, asbestos cloth or any suitable pulverulent
substance can be substituted for ordinary sand. Or they will exert
a less water pressure upon their surface and cracks or fissures will not be so likely
to be caused upon the gelatinous layer which is the chief point of a good filter.
As the chief advantage I may point out the following, that is to say, my ap-
paratus will enable these final filters to prolong the time when they give a suffi-
cient output whilst at the same time supplying the best quality of water.
My apparatus is represented in the accompanying drawing, in which :-
Figure 1 is a longitudinal section:
Figure 2 is a horizontal section; and,
.
Figures 3, 4 and 5 are transverse sections respectively on the lines 3--3, 4-4
and 5-5 of Figures 1 and 2.
The apparatus is composed of several compartments or tanks A, B, C, D
arranged in groups or separately and at the same level, and constructed of
masonry, wood, sheet-iron or any other suitable substance. These compartments
can be made of any shape but they are preferably rectangular whilst their dimen-
sions correspond to the degree of purity to be obtained and to the output required.
Each of the said compartments is furnished with a false bottom of perforated
sheet-metal plates a of about 1 metre by 2 metres in size. The said sheets have a
thickness of from 4 to 6 millimetres and are supported at their edges by iron sup-
ports bor by masonry. The bottom, c is of lime concrete or of cement and has a
strong inclination in the direction of the length of the apparatus whilst the sides

page_text: have a strong inclination towards the centre thereof.
At the inlet end of each
compartment there is formed a trough E of masonry and separated from the said
compartiment by a partition having a valve at its lower part. The outlet end
is similarly provided with a trough F of masonry and separated from the filter com-
partment by a partition i which is furnished at its lower part with valves here-
inafter described.
For the purpose of explanation I will describe an apparatus having four
grouped compartments.
The first compartment A is furnished with a sheet-metal bottom provided with
round perforations of from 10 to 12 millimetres or more or less, if desirable.
These sheets are provided with a layer, of from 15 to 20 centimetres in thickness,
of gravel sifted to a size larger than the holes. The gravel is laid with a slight
inclination towards the outlet. The second compartment is also provided with
sheet metal having round holes which are smaller than those of the first compart-
ment, for example from 6 to 8 millimetres. It is furnished with gravel sifted to
a size smaller than that of the holes but less than that of the gravel in the
former compartment.
The third compartment is provided with a sheet-metal bottom having holes
which are preferably oblong but of a section less in diameter than the holes of
the second compartment, for example, from 4 to 5 millimetres. It is supplied with
gravel sifted to a size less than that of the preceding compartment.
The fourth, which may be larger than the three others, is provided with a
sheet-metal bottom similar to that of the second compartment and with gravel
of the same size, but this gravel is covered with a bed of about 2 to 3 centimetres
or more in thickness, of coarse sand for the purpose of assisting to compensate for
the impossibility of boring holes smaller than the thickness of the sheet-metal.
Each of these compartments is provided with sliding valves for the admission
of the impure water, for the escape of the filtered water and for
the discharge of the cleansing water as also for cleaning the lower
portions thereof. They are provided with a set of valves which
enables each basin to be isolated or to be put into communication with any other
basin of the group. This set of valves consists of a kind of chamber d, e, f of
masonry or of cast or sheet metal. The said chamber, which is open at one side,
is provided with two valves (or cocks) d, ; e¹, e², or f¹f each adapted to dis-
charge the volume of water filtered by the tank to which it is fitted. The
chamber is constructed or placed in any suitable part of each of the filtering
tanks in such a manner as to receive all the water issuing from below the filtering
layer without however, being exposed to the risk of being reached by the un-
filtered water. One of the valves d, e, f conveys the filtered water into one of
the troughs of the neighbouring tank from which it flows on to the filtering
medium in this said basin. The other valves d, e, f give access to a passage
or to a pipe which delivers the filtered water to a tank other than the neighbour-
ing tank, for example, to the first, to the third or to the fourth missing
the second or the third, and from the second to the fourth missing the third.
This arrangement offers distinct advantages when cleansing as will be hereinafter
seen, and by its use it is possible to continue filtering uninterruptedly.
G
The impure water is admitted to the compartment A through a valve g which is
fitted in front of a trough. It passes through an overflow to the top of the parti-
bion hand upon the coarsest gravel, upon which it deposits its coarsest impurities.
and then flows through the perforated sheet-metal bottom and passes into one of
the troughs of the second compartment. When this water, filtered once, has filled
the bottom of the first compartment and the trough of the second, it spreads
over the gravel of the second compartment by passing over the partition i, is freed of
other impurities, of less size than the preceding, flows through the sheet-metal
bottom and passes through a trough to the gravel of the third compartment.
There the water is again filtered, passes through the finest gravel leaving its

page_text: minute impurities behind and then spreads over the coarse sand of the fourth
compartment where it deposits nearly all the remaining materials which it may
contain in suspension. The water is thus for the fourth time freed from the
largest part of its impurities or of its microbes. The large fine sand filters will
only have a very slight amount of work to do to eliminate the rest and to obtain
the results hygienically required.
After a certain number of days, weeks or months according to the nature of
the water treated, the impurities stop up the interstices in the gravel layer. The
efficiency of the apparatus is therefore reduced, and it is necessary to remove the
deposit, the major portion of which is upon the surface of the gravel. By means
of the valve-box above described, the tank to be cleaned is isolated, leaving
three others in operation. By the admission valve in connection with this tank
a certain quantity of water is admitted to the surface of the gravel. This water,
which is caused to flow by the inclination or slope above mentioned, removes
a portion of the impurities, but to accelerate the operation, two men pass light
rakes over the surface and the gravel which had become black, will be seen to
gradually resume its natural colour. The operation is very quickly performed.
When it is finished the tank is again connected with one of the others and ultra-
tion, which is effected in three tanks during the cleansing operation, again takes
place in the four tanks and the normal output can be practically reattained.
When the same tank has been superficially cleansed several times, for example,
three or four, it may happen that the gravel layers are completely impregnated
throughout their whole thickness. The efficiency of the apparatus is then very
considerably diminished and it becomes necessary to thoroughly clean the tank.
To this end the said tank is isolated by means of the valve-box as before. It is
then dried and workmen, provided with shovels, enter the tank through the outlet
and make a hole in the gravel over the whole width of the tank or chamber so as
to uncover a part, for example about one square metre, of the sheet-metal. They
then allow a stream of water of from 3 to 4 centimetres in thickness to enter
through the inlet valve. This water flows over the gravel and falls into the
excavated portion at the feet of the workmen, passes through the holes in the
sheet-metal bottom and escapes through the discharge valve. The workmen
then leave their shovels and by means of spades work the gravel and rinse it over
the perforated sheet-metal bottom. The slime which it disengages passes through
the perforations in the sheet metal bottom and thence to the discharge. The work-
men advance slowly and with dry feet towards the outlet leaving behind them clean
gravel. To finish the operation and to give to the filtering material its normal
appearance, they can open the valve which communicates with the next tank so
as to allow water to flow through the filtering layer from below upwards the said
water carrying with it the last impurities contained in the meshes of the filter.
When the gravel has reattained its normal state the tank again put into
communication with the others. The normal efficiency is then again attained.
It will be seen that the arrangement of the apparatus enables the filtering
media to be cleaned without having to remove or renew them. These gravels
serve indefinitely and are always in good working condition. The very thin layer
of coarse sand which is spread over the gravel of the first compartment disappears
like the slime during the cleansing. It is the sole material to be renewed. It
is also to be noted that as a result of the general arrangement of the under por-
tion of the apparatus, the false bottoms have during the cleansing operation been
made as clean as when the apparatus is first used.
Every part of my filter can, therefore, be inspected without expense or difficulty
and without the necessity of stopping the operation of the apparatus.
When the valve of the apparatus d is open and the valve closed, the
filtered water in the basin A passes into the basin B. When, on the contrary, the
valve is closed and the valve open, the filtered water from the basin A
passes into the passage G and from there into either one of the basins C and D
through the valve jor k,

page_text: in all industries which use large quantities of water. 16. For supplying towns
expenses can be reduced and the surest guarantee of good operation is offered.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. Filtering apparatus composed of one or more compartments which are
grouped or separate and placed upon the same level and which are of suitable
dimensions and constructed of masonry, sheet metal, wood or other suitable mate-
rial, substantially as hereinbefore described.
2. In apparatus of the kind described in Claim 1, the arrangement in each com-
partment of a false bottom of perforated sheet-metal having a layer of gravel of
a more or less degree of fineness for effecting the progressive filtering, substanti-
ally as herein before described.
3. In apparatus of the kind in the preceding claiming clauses, described, the
arrangement of cleansing valves whereby the filtering material or medium can be
cleaned whilst in position and thus be indefinitely used without being removed,
substantially as herein before described.
4. In filtering apparatus of the kind described in the preceding claiming
clauses, an arrangement of chambers of masonry, cast or sheet metal, wood, india
rubber stone-ware or of any other suitable material, and of valves suitably
arranged for opening or closing the communication between the different c m-
partments composing the whole apparatus, whereby a continuous filtering is pos-
sible even during the cleansing of one or more of the. tanks which can be isolated
to this end, substantially as herein before described.
D
1
1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.