An Improved Method for Softening and Clarifying Water and Apparatus therefor.
Year: 1889

page_text: Date of Application, 1st Feb., 1889
Complete Specification Left, 30th Oct., 1889-Accepted, 21st Dec., 1889
PROVISIONAL DE FUIFICATION.
An Improved Method for Softening and Clarifying Water and
Apparatus therefor.
WE, LEONARD ARCHBUTT of Argyll Terrace, Rose Hill, Derby, in the County of
Derbyshire, Analytical Chemist, and RICHARD MOUNTFORD DEELEY, of Parkfield
Terrace, Stafford Street, Derby, in the County of Derbyshire, Mechanical Engineer
do hereby declare the nature of this invention to be as follows:-
In softening water by Clark's process it is well known that the precipitate take s
many hours to settle, and that although by the use of a salt of alumina or certain other
compounds the subsidence of the precipitate may be materially hastened, yet the
clarification of the water is in many cases still but imperfectly effected.
This invention relates to an additional process whereby even very dirty water may
be softened and rapidly clarified to a sufficient extent for use in boilers, on a large
scale, by simple means, and in tanks of moderate size.
Another part of the invention relates to an arrangement whereby the chemical
reagents may be easily and thoroughly mixed with the water to be softened. It will
be convenient to describe this part of the invention first.
In carrying out the process the chemical reagents, including, if necessary, the salt
of alumina or other coagulating compound, are in the first instance mixed with, or
dissolved in, water in a sinall tank out of which the prepared liquid is caused to flow,
through a tap, into a well fixed to the side of a larger mixing and settling tank. Near
the bottom of the well, opposite a pipe projecting into the settling tank, is fixed a
trajector, for the purpose of creating a current of water passing from the well through
the pipe into the tank. As the sides of the well are partly open to the water in the
tank, the trajector causes a circulation of the water to take place through the tank and
well. Into this current the reagents pass, and are thus thoroughly mixed with the
water to be softened.
To effect the rapid subsidence of the precipitate, perforated pipes are laid near to
the bottom of the tank in such a way that by forcing steam and air, or air alone, into
these pipes, and out through the perforations, the old nud resulting from previous
softenings is partly stirred up and mixed with the suspended precipitate. The fresh
precipitate and the stirred-up mud then settle rapidly together, leaving the water
soft and with such a trifling quantity of suspended matter in it as may be neglected
for many technical purposes. By using a flexible or hinged exit pipe, so that the
orifice of the pipe can be supported by a float near the surface of the water in
the tank, the drawing off of the water may be commenced a few minutes after
the completion of the mixing process. To carry on the process continuously two
tanks are arranged side by side and hard water is filled into one tank and softened,
while soft water is being drawn from the other for use.
When the mud has.accumulated to a depth of about one foot at the bottom of each
tank it is removed. The soft water is drawn off so low as to leave about an inch of
clear water for every inch of mud. The mud is then stirred up by means of ordinary
brooms, and while being kept in agitation it is caused to flow through a large opening
in the side of the tank into a trough which carries it away into a drain or other
convenient receptacle. About one inch in depth of mud must be left in the tank in
order to carry on the clarifying process.
Dated this 28th day of January 1889.

page_text: COMPLETE SPECIFICATION.
An Improved Method for Softening and Clarifying Water and
Apparatus therefor.
WE, LEONARD ARCHBUTT late of Argyll Terrace, Rose Hill Derby in the County of
Derby Analytical Chemist and now of 11 Charnwood Street Derby and RICHARD
MOUNTFORD DEELEY of Parkfield Terrace Stafford Street Derby in the County of
Derby Mechanical 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 :-
In softening water by Clark's process it is well known that the precipitate-takes
many hours to settle and that although by the use of a salt of alumina or certain other
compounds the subsidence of the precipitate may be materially hastened, yet the
clarification of the water is in many cases still but imperfectly effected.
This Invention relates to an additional process whereby even very dirty water may
be softened and rapidly clarified to a sufficient extent for use in boilers on a large
scale by simple means and in tanks of moderate size.
Another part of the Invention relates to an arrangement whereby the chemical
reagents may be easily and thoroughly mixed with the water to be softened. It will
be convenient to describe this part of the Invention first.
In carrying out the process the chemical reagents including if necessary the salt of
alumina or other coagulating compound are in the first instance mixed with or
dissolved in water in a small tank a out of which the prepared liquid is caused to
flow, through a tap b, into a well c fixed to the side of a larger mixing and settling
tank d. Near the bottom of the well, opposite a pipe projecting into the settling tank
is fixed a trajector e for the purpose of creating a current of water passing from the
well c through the pipe into the tank d. As the sides of the well c are partly open to
the water in the tank d, the trajector e causes a circulation of the water to take place
through the tank d and well c. Into this current the reagents pass and are thus
thoroughly mixed with the water to be softened.
To effect the rapid subsidence of the precipitate perforated pipes are laid near to
the bottom of the tank d in such a way that by forcing steam and air or air alone into
these pipes and out through the perforations the old mud resulting from previous
softenings is partly stirred up and mixed with the suspended precipitate. The fresh
precipitate and the stirred up mud then settle rapidly together, leaving the water soft
and with such a trifling quantity of suspended inatter in it as may be neglected for
many technical purposes. By using a flexible or hinged exit pipe g so that the orifice
of the pipe can be supported by a float h near the surface of the water in the tank, the
drawing off of the water may be commenced a few minutes after the completion of
the mixing process.
To carry on the process continuously two tanks are arranged side by side and hard
water is filled into one tank and softened while soft water is being drawn from the
other for use.
When the mud has accumulated to a depth of about 1 foot at the bottom of each
tank it is removed. The soft water is drawn off so low as to leave about an inch of
clear water for every inch of mud. The mud is then stirred up by means of ordinary
brooms, and, while being kept in agitation, it is caused to flow through a large
opening in the side of the tank (not shown in the drawings) into a trough which
carries it away into a drain or other convenient receptacle. About 1 inch in depth of
mud must be left in the tank in order to carry on the clarifying process.
In carrying out the process, we prefer to use sulphate of alumina as the coagulating
material, and in the proportion of about two thirds of 1 grain of crystallized sulphate
of alumina for every gallon of water treated, which is generally sufficient. In certain
cases, where the hard water contains much magnesium salt which is decomposed by
caustic soda in the softening process, the bulky magnesium hydrate precipitate produced
may serve the same purpose as alumina, and the use of sulphate of alumina may be

page_text: unnecessary. If sulphate of alumina is to be used, the proper quantity is dissolved. in
a small quantity of hot water in the small chemical tank a, the water being heated by
means of a steam pipe, not shown in the drawings, and the solution is rapidly run out
into the well c by opening the cock b. At the same time the trajector e is set into
action. The chemical reagents required for the softening of the water, consisting of
lime, or caustic soda, or carbonate of soda, or a mixture of two or more of these, in
proper quantities and proportions for the treatment of the hard water, together with
such additional quantity of one or more of them as is needed to decompose the
sulphate of alumina, are successively or collectively dissolved or mixed with a further
supply of hot water in the tank a, or the chemicals may be added to the same water
the sulphate of alumina is dissolved in, and the prepared liquid is run into the well c.
After the chemicals have been added, the trajector is allowed to work for about
5 minutes longer, and by this time the admixture of the chemicals and the hard water
in the large tank d will be complete. The working of the trajector e is then stopped,
and the perforated air pipes fare brought into action for about fifteen minutes, with
the result that a quantity of mud from previous softenings is brought up from the
bottom and diffused throughout the water. The turbid water is then allowed to
become quiescent, and in the course of about thirty minutes under favourable
conditions it will have become so clear, that at a depth of six feet from the surface the
amount of suspended matter will not exceed one grain in every gallon of the water,
and may be less than that.
The apparatus described above is especially adapted for the treatment of waters
which vary in composition, such as river waters, for, by means of the trajector e the
diffusion of the chemicals throughout the hard water is so easily and rapidly performed,
that if it should be found by the nitrate of silver or other test that an insufficient
quantity of lime or other reagent has been added in the first instance, a further
quantity, treated with water in a bucket and poured into the well c can be speedily
mixed with the hard water in the large tank d and the deficiency thus made up.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In purifying water by precipitation mixing it with the precipitate of former
operations.
2. The process of purifying water consisting of introducing it into a vessel con-
taining the precipitate of former operations mixing it with any suitable precipitant,
stirring up the old precipitate and mixing it with the water, allowing the old and new
precipitate to settle together and drawing off the clear water.
3. The combination of a settling tank, apparatus for mixing a precipitant with the
water and apparatus for stirring up the old precipitate.
4. The combination of the tank & the trajector e and perforated pipes f with or.
without the tank a substantially as described.
5. Apparatus for softening and clarifying water substantially as described and
shown in the drawings.
Dated this 00th day of October 1980