IMPROVE- MENTS IN DEODORIZING AND PURIFYING SEWAGE
Year: 1876

page_text: LETTERS PATENT to John William Slater, of No. 2, Tamworth Terrace, in
the County of Middlesex, Analytical Chemist, for the Invention of "IMPROVE-
MENTS IN DEODORIZING AND PURIFYING SEWAGE."
PROVISIONAL SPECIFICATION left by the said John William Slater at the
Office of the Commissioners of Patents on the 2nd August 1876.
JOHN WILLIAM SLATER, of No. 2, Tamworth Terrace, in the County of Middlesex,
Analytical Chemist. "IMPROVEMENTS IN DEODORIZING AND PURIFYING SEWAGE."
In every process for purifying sewage it is desirable to add to it some substance
which shall have a decolourizing and deodorizing action.
Now my Invention consists in treating sewage with the deodorizing and
decolorizing agents herein-after specified.
According to one process I mix with the sewage certain alkaline, alkaline earthy,
carthy or metallic salts of hyposulphurous, sulphurous, and thionic acids, that is to
say, the salts of soda, potash, lime, strontia, magnesia, alumina, iron, and manganese,
or any other salts of these classes which contain any of the above acids, and are
innocuous and cheap, and will effect the purpose; of these salts I prefer for
convenience and cheapness the byposulphite and sulphite of lime, which exist in a
crude state in the substance known as "tank waste" or "vat waste," such waste
being the residuum left after the lixiviation of "black ash" or "black balls" in the
manufacture of soda. This "tank waste" when fresh consists principally of the
sulphide and carbonate of calcium.
In order to prepare the said waste for my purpose I allow the said waste to remain
exposed to the action of the air and moisture, or I assist the oxidation by spreading
out the said waste and sprinkling it with water, or by exposing the said waste to
the action of steam.
Should the said waste contain much sulphide of calcium I add to it dilute
sulphuric acid or muriatic acid, in such quantities as may suffice to decompose the
said sulphide of calcium, but not to decompose any sulphites or hyposulphites or
thionites which may have been formed. I add the hyposulphite or sulphite of lime
thus prepared or prepared in any other way to the sewage, either by itself or in
[Price 401

page_text: conjunction or admixture with any other deodorizing or purifying agents or
deodorizing or purifying mixtures.
The sewage treated with the said hyposulphite or sulphite of lime alone may be
either filtered and passed on to land or into a river, or it may be so disposed of
without filtration.
My Invention consists further in adding to sewage when precipitating its
impurities with a salt of alumina or of iron a solution of impure chloride of
calcium (which is a residual product in certain manufactures (e.g. Weldon's process
of regenerating manganese), or free muriatic acid, or both these additions are
especially useful in the treatment of sewage containing the waste liquor from tan-
yards.
My Invention further consists in treating sewage with infusorial carth, that
substance having a decolorizing action.
By my Invention charcoal may be wholly or in a great measure dispensed with
in the treatment of sewage, the substances added as hercin-before described being
cheap substitutes for charcoal.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John William Slater in the Great Seal Patent Office on the 30th January
1877.
JOHN WILLIAM SLATER, of No. 2, Tamworth Terrace, in the County of
Middlesex, Analytical Chemist. "IMPROVEMENTS IN DEODORIZING AND PURIFYING
SEWAGE."
In every process for purifying sewage it is desirable to add to it some substance
which shall have a decolourizing and deodorizing action.
Now my Invention consists in treating sewage with the decolourizing and
deodorizing agents herein-after specified.
According to one process I mix with the sewage certain alkaline, alkaline carthy,
earthy or metallic salts of hyposulphurous, sulphurous, and thionic acids, that is to
say, the salts of soda, potash, lime, magnesia, alumina, iron, and manganese, or any
other salts of these classes, which contains any of the above acids and are innocuous
and cheap, and will effect the purpose. Of these salts I prefer for convenience and
cheapness the hyposulphite and sulphite of lime, which exist in a crude state in
the substance known as "tank waste" or "vat waste," which has been exposed to
the weather or otherwise oxydised, such waste being the residuum left after the
lixiviation of "black ash" or "black balls" in the manufacture of soda. This tank
waste when fresh consists principally of the sulphide, oxysulphide, and carbonate of
calcium.
I will describe this part of my Invention as carried into effect by means of the
hyposulphite and sulphite of lime.
In order to prepare the aforesaid waste for my purpose the said waste must be
exposed to the action of the air and moisture, or Ì assist the oxidation by spreading
out the said waste and sprinkling it with water, or by exposing the said waste to
the action of steam.
Should the said waste contain much sulphide of calcium I add to it dilute
sulphuric acid or muriatic acid, in such quantities as may suffice to decompose the
said sulphide of calcium, but not to decompose any sulphites or hyposulphites, or
thionites which may have been formed. I add the hyposulphite and sulphite of
lime thus prepared or prepared in any other way to the sewage either in
conjunction or admixture with any other deodorizing agent or agents, such as the
mixtures used by the Native Guano Company, so far as they are not chemically
incompatible with the use of the agents herein-before referred to. Where a low
standard of purity in the effluent is admissible, as in cases where the effluent runs

page_text: into the sea or into a tidal river or over land, the sewage treated with the said
hyposulphite and sulphite of lime alone may be either filtered and passed on to
the land or into such river, or it may be so disposed of without filtration.
If I wish merely to decolourize and deodorize the sewage I add to 1000 gallons
thereof about 10 lbs. of the mixture of hyposulphite and sulphite of lime herein-
before referred to, selecting by preference, such as is neither too new nor too old,
and gives out a sharp and distinct smell of sulphurous and hyposulphurous acids
on admixture with (say) its own weight of muriatic acid, and which has been
treated, if necessary, with muriatic acid, as herein-before described. This mixture
of salts I grind or stir up to a paste with water (for which purpose some of the
sewage may be employed), and I then allow the mixture to flow into the sewage so
as to be diffused through it, or I mix the said mixture with the said sewage by any
suitable means.
If I wish to effect a more perfect purification of the sewage than can be effected
by the use of the hyposulphite and sulphite of lime alone, I use such hyposulphite
and sulphite of lime in conjunction or admixture with suitable precipitating or
purifying agents, such as sulphate or muriate of alumina (whether artificially
prepared or existing in minerals or waste products) or gelatinous silica, or silicates
of the alkalies and clay.
I do not limit myself either to the purifying agents or the proportions thereof to
be used with the hyposulphite and sulphite of lime, but the following is an
example of a deodorizing and purifying mixture which answers well in practice, the
said mixture being sufficient for the treatment of 1000 gallons of sewage :-
Hyposulphite and sulphite of lime
Sulphate of alumina
Clay
-
10 lbs.
6 lbs.
20 lbs.
I mix these agents with the sewage, and in cases where the effluent is acid I
render it neutral by the addition of lime or other cheap alkaline substance.
When the sewage to be treated contains a large proportion of waste tan liquors
I add to the hyposulphite and sulphite of lime, either by itself or in conjunction or
admixture with other suitable agents, chloride of calcium, the said chloride being
used by preference in the proportion of 4 or 5 lbs. to every 1000 gallons of sewage,
and I add this mixture to the sewage. Where chloride of calcium is not readily
procurable I add to such sewage, in addition to the hyposulphites and other agents
(if any) used therewith, muriatic acid in the proportion by preference of 1½ lb.
to 1 lb. of the said acid to every 1000 gallons of the said sewage. But I do not
claim the use of chloride of calcium.
From the foregoing instructions for the treatment of sewage with hyposulphite
and sulphite of lime, the treatment of sewage with the other alkaline, alkaline
earthy, earthy or metallic salts of hyposulphurous, sulphurous, and thionic acids,
will be readily carried into effect.
I would here observe that I am aware that it has been proposed to treat sewage
with a substance termed by some "black ash," but if tho real "black ash" be used
it is too expensive, and practically ineffectual, and it does not contain the oxydised
sulphur compounds herein-before referred to, which I wish to use, I therefore make
no claim to the use of "black ash." If however the term "black ash" be erroneously
used to designate the insoluble substances remaining after the lixiviation of real
"black ash" the same objections hold good, inasmuch as this tank waste is of very
little use in its fresh state, and only contains the oxydised sulphur compounds
which I require after "weathing," or after artificial oxidation.
My Invention consists further in treating sewage with infusorial earth, that
substance having a decolourizing action; I mix the said earth with the sewage in
the proportion of from 10 to 20 lbs. of the said earth to 1000 gallons of the sewage,
either alone, or (which I prefer) along with sulphate or muriate of alumina,
hydrated silica, and clay, or with other agents. The said infusorial earth inay also
be used as a filtering medium for filtering sewage or the effluent therefrom; or the
sewage may be treated with the said earth in both these ways.

page_text: Having thus described the nature of my Invention, and the manner in which the
same is to be performed, I wish it to be understood that I do not limit myself to
the precise details hercin-before described, as they may be varied without departing
from the nature of my said Invention, and I make no claim to the use of sulphites
by themselves, i. c., without admixture with byposulphites, but I claim as my said
Invention,―
Firstly. The use of the mixture of hyposulphite and sulphite of lime herein-
before referred to in the treatment of sewage, essentially as herein-before describod.
Secondly. The treatment of sewage with infusorial carth, essentially as herein-
before described, that is to say, either mixing the said earth with the sewage or
filtering the sewago through the said earth, or both.
In witness whereof, I, the said John William Slater, have hereunto set my
hand and seal, this Twenty-ninth day of January, in the year of our Lord
One thousand eight hundred and seventy-seven.
Witness,
H. H. MURDOCH,
Staple Inn,
London.
J. W. SLATER. (L.S.)