IMPROVEMENTS IN THE PURIFICATION OF SEWAGE WATER
Year: 1873

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Ealing, in the
County of Middlesex, Major-General, C.B., for the Invention of
"IMPROVEMENTS IN THE PURIFICATION OF SEWAGE WATER."
"IMPROVEMENTS IN THE PURIFICATION OF SEWAGE WATER."
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his Petition,
on the 18th November 1873.
I, HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of
Middlesex, Major-General, C.B., do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE PURIFICATION OF SEWAGE WATER,"
to be as follows:-
-;
This Invention relates to the treatment of sewage water colored with
dyes for the purpose of removing the color therefrom.
In applying my Invention I prefer to commence the treatment of the
sewage by the lime method of precipitation, using no more lime than is
essential for clarification. The resulting precipitate is received into a
tank, say, No. 1, and the effluent from it is then treated with sulphate

page_text: or chloride of iron or alumina. This will again occasion a precipitate,
which is to be allowed to deposit in tank No. 2. As much of the preci-
pitant is added as will nearly but not quite neutralize the alkalinity of
the water.
The effluent from tank No. 2 is next sufficiently acidified with
hydrochloric acid or oil of vitriol to change the color of delicate litmus
paper.
The above treatment of sewage water colored by dyes will have the
effect of rendering the water colourless as well as free from suspended
matters.
In lieu of using salts of iron or alumina I sometimes obtain the
precipitant for tank No. 2 by digesting animal charcoal prepared either
from bones or resulting from the manufacture of prussiate of potash
with hydrochloric or muriatic acid, and I add the solution thus obtained
either separately or in conjunction with the charcoal to the sewage
water, or again I sometimes dissolve impure phosphates or either of the
above acids, and add the solution thus obtained to the sewage water in
tank No. 2.
Although I prefer the above order of procedure it is not essential to
the chief object of this Invention (viz., deodorization of dyes in sewage)
that tank No. 2 shall be employed, as the operations in tank No. 1 and
No. 2 may be combined when the precipitant is of little value, and in
certain cases the second operation omitted altogether.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Young Darracott Scott in the Great Seal 25
Patent Office on the 18th May 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex,
Major-General, C.B., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 30
Letters Patent, bearing date the Eighteenth day of November, in the year
of our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,

page_text: give and grant unto me, the said Henry Young Darracott Scott,.
Her special licence that I, the said Henry Young Darracott Scott,
my executors, administrators, and assigns, or such others as I, the
said Henry Young Darracott Scott, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN THE PURIFICATION OF
SEWAGE WATER," upon the condition (amongst others) that I, the said
Henry Young Darracott Scott, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Henry Young Darracott Scott,
do hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement (that is to say) :—
This Invention relates particularly to the treatment of sewage which
is colored with dyes or other impurities for the purpose of removing
the colour therefrom.
Purification in other respects, such as deodorization and the removal
of nitrogenous matter, will also be effected by the process.
In applying my Invention I commence the treatment of the sewage
by the ordinary lime method of precipitation, using as a general rule
about twenty grains of lime per gallon, but I employ larger quantities
when the coloring matters are very strong. The resulting precipitate
is received into a tank, say, No. 1, and the deposited matters may be
employed as manure or for the preparation therefrom of agricultural
lime or cements by well known methods.
The effluent from tank No. 1, which will consist of limed sewage
water, is treated or agitated with an impure sulphate or chloride of iron
and alumina, which I prepare by digesting prussiate of potash charcoal
in dilute sulphuric or hydrochloric acid. The effect of this chemical

page_text: agent on the sewage will be to produce a further precipitate consisting
of salts of iron and alumina mixed with the carbonaceous matter of the
charcoal, which mixture will exercise a powerful deodorizing and de-
colorizing action upon the sewage water. These actions may be further
increased by using a slight excess of the above mentioned precipitant as
compared with the lime contained in the effluent from tank No. 1, so
that not only is the lime completely neutralized but the effluent from
tank No. 2 will pass off slightly acidified, or the same object may be
effected by adding an equivalent proportion of free acid to the sewage to
produce a like result.
The quantity of the precipitant (produced from the prussiate of
potash charcoal), and which must be used with the sewage from tank 1,
and which must be agitated with it, will depend on the strength of the
dyes, and the quantity of the precipitant required for this purpose will
vary between very wide limits.
In some instances from twenty-five to fifty grains of the charcoal to
every gallon of the sewage will supply enough carbon and salts of iron and
alumina to produce decolorization of the sewage, but in other cases I
have found as much as two hundred grains per gallon was necessary to
produce the desired effect. The proportion of acid as compared with the
amount of charcoal required for the preparation of the compound will
depend on the composition of the prussiate of potash charcoal, but the
following will be found to produce good results in average cases, viz.,
one part by measure of commercial hydrochloric acid, to which five
parts of water are added and five parts of the refuse charcoal. After
these ingredients have remained together for some time (say, about an
hour) their thorough incorporation and admixture may be rendered
complete by passing the mass under an edge runner in an ordinary
mortar mill. Any other contrivance for thoroughly mixing the ingredi-
ents may however be employed if preferred.
The precipitant obtained in tank No. 2 by the addition of this mixture
may, after straining off the greater part of the water, be used again for
the precipitation of a fresh charge of limed effluent from tank No. 1, it
being only necessary to treat the mixture with hydrochloric acid, as
before, which will have the effect of redissolving the precipitated iron and
alumina. This operation may of course be repeated over and over again.
The expense of this part of the process will thus be limited to the labour

page_text: and the cost of the hydrochloric acid, which in some parts of the country
may to a great extent be considered a waste product.
I sometimes use the spent charcoal of sugar refineries for the second
part of the process, viz., that which is performed in tank No. 2. In this
case I employ enough acid to bring all the phosphoric acid or a con-
siderable proportion of it into the soluble condition. The precipitate
thus produced consists chiefly of phosphate of lime and charcoal.
Mineral phosphates dissolved in acid may be used in conjunction with
the animal charcoal, and the deposit, when the cleansing powers of the
charcoal are wholly exhausted, may be disposed of as manure, together
with the precipitated phosphates with which it has thus become mixed.
Although I prefer the above order of procedure it is not essential to
the chief object of this Invention (viz., the decolorization of sewage) that
tank No. 2 shall be employed. For instance, prussiate of potash charcoal
being but of trifling value the charcoal prepared therefrom may be added
with the lime or before or immediately after it in tank No. 1. When
however the precipitant has the value which spent animal charcoal from
the sugar refineries adds to the precipitate this course is inexpedient, as
the worthless suspended matters in the raw sewage degrade the quality
of the resulting manure.
Having now described my Invention of "Improvements in the Purifi-
cation of Sewage Water," and having explained the manner of carrying
the same into effect, I wish it to be understood that under the above in
part recited Letters Patent I claim, purifying sewage water by producing
a precipitate therefrom, and removing the coloring matters contained
therein by means of compounds of iron and alumina or lime with carbon,
such compounds being derived from the treatment of prussiate of potash
or other refuse animal charcoal with hydrochloric or sulphuric acid, as
herein set forth.
In witness whereof, I, the said Henry Young Darracott Scott,
have hereunto set my hand and seal, the Sixteenth day of May,
in the year of our Lord One thousand eight hundred and
seventy-four