IMPROVEMENTS IN THE TREATMENT AND DEODORIZATION OF SEWAGE WATER
Year: 1865

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Ealing, in the
County of Middlesex, Lieutenant-Colonel in the Royal Engineers, for
the Invention of "IMPROVEMENTS IN THE TREATMENT AND DEODORIZATION OF
SEWAGE WATER."
Sealed the 24th April 1866, and dated the 31st October 1865.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his Petition,
on the 31st October 1865.
I, HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex,
Lieutenant-Colonel in the Royal Engineers, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE TREATMENT AND DEODORIZATION OF
SEWAGE WATER," to be as follows:-
The object of this Invention is to provide a method of getting rid in a
cheap and efficient manner of the nuisance and danger attendant upon the
discharge of fluid sewage matter into our rivers and as a manure over our
fields. The methods of deodorization hitherto employed by means of lime or
metallic salts have either been imperfect from the inefficiency of the remedy,
or have been abandoned on account of their expense. The lime process yields
with sewage matter a precipitate and deposit which is harmless when dry, but

page_text: in the process of drying smells very offensively, and the liquid sewage which
passes off is temporarily deodorized, but after a time it undergoes changes by
which fetid gas is again evolved. In great part the offensive smell of sewage
is due to sulphuretted hydrogen, and on this account certain soluble metallic
salts, particularly perchloride or sulphate of iron, have been recommended as
deodorizers, since such salts not only precipitate the phosphoric and carbonic
acid of sewage waters, carrying down with the phosphates and carbonates
formed the flocculent suspended matter, but lock up in a quite innocuous form
the sulphuretted hydrogen they come in contact with. The latter mode of
treating the sewage matter is therefore considered far more satisfactory
than any other that has been attempted, but its expense is a serious objection
to its use.
Now my Invention consists in doing with lime, a comparatively cheap
material, that which lime will effect as well as metallic salts, and supple-
menting its action with the properties which the far more costly metallic salts
possess of locking up in a harmless form the noxious sulphuretted hydrogen.
It is not sufficient to throw into the sewage water compounds consisting of
lime and metallic salts, or to add them simultaneously to the fluid sewage, as
has sometimes beeu proposed, for the lime by precipitating the bases of the
metallic salts as oxides temporarily neutralizes their tendency to seize hold of
the sulphuretted hydrogen. The lime, therefore, must be allowed first to do
its work on the phosphoric acid and carbonic acid present, and to this end I
subject the sewage water to the action of the lime in a receptacle which I
will designate reservoir No. 1. When the required deposit is obtained I run
off the supernatant liquid into reservoir No. 2, and subject it then to the
action of sulphate or perchloride of iron, either of which salts will seize upon
the sulphur of the soluble sulphurets contained in the liquor. In this manner
the effluent sewage may be reduced to a harmless condition, but where it is
necessary also to deodorize that portion of the sulphuret of calcium and other
sulphurets which remain mechanically mixed up with the lime precipitates
and deposit in reservoir No. 1, I proceed as follows:-I have already stated
that so far as the effluent liquid is concerned the metallic salt is wasted, and
the deodorizing not permanently effectual if the metallic salt and the lime
be applied together, since the metallic oxide thrown down by the alkaline
earth willnotinstantaneously combine with the sulphur of soluble sulphuretted
compounds, which will be discharged as such into watercoursesand be removed
from the action of the iron oxide. Nevertheles if time and opportunity be
given such combination will take place, and it is only necessary to procure the
intimate admixture of hydrated metallic oxides with the deposited sludge of

page_text: the lime precipitate to ensure that the sulphurets entangled with it shall
gradually give up their sulphur to them. To bring this about the metallic
salt (that which I prefer using in order to obtain the hydrated oxide of
iron being the sulphate) should be stirred in with the milk of lime before
it is added to the sewage water, for if thrown in with a portion of the metal
will be taken up by the phosphoric or carbonic acids of the sewage to form
phosphates and carbonates of iron, which are not so readily decomposed
again by sulphur compounds as soluble salts of iron, and thus unnecessary
expenditure of iron will take place.
The next portion of my Invention consists in the arrangements by which I
prefer (though as above appears I do not limit myself to these arrangements)
to bring the precipitating and chemical agents into contact with the sewage
matter. For this purpose I prefer using these agents combined in a consoli-
dated form, the blocks or pieces being of such shape and size as will permit of
their being piled together to form filter beds. While thus serving as a filter
the blocks or pieces will under the action of the flowing liquid gradually pass
iuto solution, and the portions dissolved will act as precipitants (Isupposethe
grosser fecal matters to be caught in depositing tanks and wicker or other
separations and rough filters before my treatment begins). In bringing the
lime into the form of sufficient firmness for the purpose I make use of 5 to
10 per cent. of sulphate of iron, which salt when intimately mixed with finely
divided lime will, the lime being somewhat dead, control its violence of action
on its being made into paste with water so far as to enable it to harden,
The
slaking and setting simultaneously, after the manner of a cement.
blocks or pieces so prepared will contain the hydrated oxide of iron necessary
to purify the sludge which will be precipitated with it as the water acts upon
the lime. The sulphate of lime resulting from the decomposition of the
sulphate of iron contained in the sewage water will also tend to prevent the
expulsion of ammonia. In making use of the pieces of lime compound thus
prepared I vary my arrangements according to the nature of the sewage and
its comparative freshness. If comparatively free from flocculent matter I
employ the blocks or pieces as flints and clinkers are employed in filtration,
but if I fear the choking of the filters I make use of a series of screens or
cases of wicker or iron work, which will retain the pieces of lime until they
are dissolved, so as to allow of the percolation of a portion only of the sewage
matter through them whilst the main portion passes through narrowchannels
formed by the screens, and these channels are so arranged as to turn the fluid
in its passage between them from side to side, and secure an intimate
mingling of the dissolved lime with the sewage matter.

page_text: To remove the sulphuretted hydrogen of the effluent sewage water I prefer
using sulphate of iron, because that salt can be procured at a cheap rate and
in crystals, which will admit of being used as I have above proposed to use
the pieces of lime compound arranged as a filter or in screens, and both in
the case of the lime and the iron salt I propose to provide my filters with
self-feeding hoppers for maintaining the filter beds in proper condition.
I have now to allude to certain modifications of my processes. In lieu
of milk of lime prepared from fat limes which readily slake abroad, I some-
times propose to use dolomitic limes; or again,lime compounds of the nature
of cements, which after calcination will not slake to powder, but if ground to
a powder and mixed in with the sewage water will act to a certain extent in
the same manner, and will give consistency to the sewage deposits. Such
compounds usually contain iron oxide which will slowly in the presence of
sulphuretted hydrogen form sulphide of iron; they also contain substances
useful as manure.
Similar compounds may be sometimes used in pieces in lieu of the artificial
lime compounds above described to form filters for the sewage matter.
.
In forming the artificial pieces of lime compound above described I some-
times mix in 10 or 15 per cent. of sulphate of lime, which will also control
its slaking, or 10 or 15 per cent. of chloride of sodium, or 5 to 10 per cent.
of perchloride of iron, which will render the pieces more soluble, and them-
selves act as disinfectants; or I may add 5 to 10 per cent. of carbolic acid
in manufacturing the pieces on account of its supposed effect on nitrogenous
matter.
Again, in lieu of employing crystals of sulphate of iron for the second part
of the disinfecting process I may employ a compound of perchloride of iron
or of sulphate of iron and artificial gypsum made into pieces which would
be less readily soluble than crystals of sulphate of iron. Thebeneficialeffects
of
gypsum on certain
crops is well ascertained, and when the sewage is to be
applied to irrigation the sulphate of lime would not be wasted. In the
preparation of such pieces of artificial gypsum and iron salts I merely mix
dehydrated sulphate of lime or plaster of Paris with a solution of the iron
salt in the right proportion to make a paste on solidification, and they are
fit for use. Carbolic acid or chloride of sodium may also be sometimes
advantageously mixed with the paste from which the blocks or pieces of
this compound are to be formed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Young Darracott Scott in the Great Seal Patent
Office on the 30th April 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex, Lieutenant-
Colonel in the Royal Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of October, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, 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
THE TREATMENT AND
Isle of Man, an Invention for "IMPROVEMENTS IN
DEODORIZATION 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
scals, 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, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to say) :-
The object of this Invention is to provide a method of getting rid in a
cheap and efficient manner of the nuisance and danger attendant upon the
discharge of fluid sewage matter into our rivers or when used as a manure
over our fields. The methods hitherto employed for deodorizing sewage by
means of lime or certain soluble metallic salts have either been imperfect
from the inefficiency of the remedy, or have been abandoned on account of
precipitate
their expense. The mixture of lime with sewage matter yields
and deposit which is harmless when dry, but during the process of drying
AL

page_text: emits a very offensive smell, and the liquid sewage which passes off is only
temporarily deodorised, as after a time it undergoes changes by which fetid
gas is again evolved. The offensive smell of sewage is mainly due to the
presence of sulphuretted hydrogen, and on this account certain soluble
metallic salts of iron, zinc, and manganese, particularly perchloride or
sulphate of iron, have been recommended as deodorisers, since such salts
not only precipitate the phosphoric and carbonic acid of sewage waters and
carry down with the phosphates and carbonates thus formed the flocculent
suspended matter, but lock up in an innocuous form the sulphuretted
hydrogen they come in contact with. The latter mode of treating the
sewage matter is therefore considered far more satisfactory than any other
that has been attempted, but its expense is a serious objection to its use.
Now my Invention consists in effecting with lime (which is a comparatively
cheap material) that which line will do as well as metallic salts, and then
supplementing its action with the properties which the far more costly metallic
salts, such as soluble salts of iron, manganese, zinc, and copper possess of
locking up in a harmless form the noxious sulphuretted hydrogen. It is not
sufficient to throw into the sewage water compounds consisting of lime and
metallic salts or to add them simultaneously to the fluid sewage as has some-
times been proposed, for the lime by precipitating the bases of the metallic
salts as oxides temporarily neutralizes their tendency to seize hold of the
sulphuretted hydrogen. The lime therefore must be allowed first to do its
work on the phosphoric and carbonic acid present, and to this end I subject
the sewage water to the action of the lime in a receptacle which I will
designate reservoir No. 1; when the required deposit is obtained I run off the
supernatant liquid into reservoir No. 2, and then subject it to the action of
sulphate or perchloride of iron, which I prefer to the other salts named, and
either of which salts will seize upon the sulphur of the soluble sulphurets
contained in the liquor. In this manner the effluent sewage may be reduced
to a harmless condition, but where it is necessary also to deodorize that portion
of the sulphuret of calcium and other sulphurets which remain mechanically
mixed up with the lime precipitates and deposit in reservoir No. 1, I pro-
ceed as follows:-I have already stated that so far as the effluent liquid is
concerned the metallic salt is wasted and the deodorizing process will not be
permanently effectual if the metallic salt and the lime be applied together,
because the metallic oxide thrown down by the alkaline earth will not
instantaneously combine with the sulphur of the soluble sulphuretted com
pounds; these latter will therefore be discharged unchanged into the water
courses, and thus be placed beyond the action of the iron oxide. Nevertheless

page_text: if time and opportunity be given the required combination will take place,
and it will only be necessary to procure the intimate admixture of the
hydrated metallic oxides with the deposited sludge of the lime precipitate
in order to ensure that the sulphurets entangled with it shall gradually give
up their sulphur to such metallic oxides. To effect this object the metallic
salt (that which I prefer to use in order to obtain the hydrated oxide of iron
being the sulphate) should be well mixed with the milk of lime before it is
added to the sewage water, for if the metallic salts be thrown into the sewage
water with the lime without being previously mixed with the latter a portion
of the metal will be taken up by the phosphoric or carbonic acids of the
sewage to form phosphates and carbonates of iron, which are not so readily
decomposed again by sulphur compounds as the hydrated oxide of iron.
The next portion of my Invention relates to a novel mode of applying the
precipitating and chemical agents so as to bring them into contact with the
sewage matter in a suitable manner. For this purpose I prefer to use these
agents combined in a consolidated form, the blocks or pieces being of such
shape and size as will permit of their being piled together to form filter beds.
In the accompanying Drawing I have shewn a convenient arrangement of
apparatus for effecting the object of my Invention. Fig. 1 is a vertical section
representing one of the filtering chambers in which the consolidated blocks of
lime compound are placed. a, a, is a hopper into which the blocks are thrown
indiscriminately, and from whence theydescend into the filtering chambersb,b,
which may be formed of perforated metal or other suitable material. The
lumps of lime compound prepared in the manner already described when
placed in the hopper descend into the vertical filteringchambers and are there
exposed to the action of the effluent sewage water as it flows through the
filters. These filtering chambers are provided with sluices or gates c, c, from
which any sludge or deposit that may accumulate at the bottom of the
filtering chamber may be removed by lifting up the sluices or gates c, c, by
means of the rods and handles c¹, c. It will now be understood that while
serving as a filter the blocks or pieces will, under the action of the flowing
liquid, gradually pass into solution, and the portions dissolved will act as
precipitants on the sewage water. The grosser fecal matters may be caught
in depositing tanks and wicker or other separating apparatus or rough filters
before my treatment begins. In bringing the lime into the form of sufficient
firmness for the purpose I make use of five to ten per cent. of sulphate of iron,
which salt when intimately mixed with finely divided lime will (the lime
being somewhat dead) control its violence of action on its being made into

page_text: paste with water so far as to enable it to slake, harden, and set simultaneously
after the manner of a cement. The blocks or pieces so prepared will contain
the hydrated oxide of iron necessary to purify the sludge which will be
precipitated with it as the water acts upon the lime. The sulphate of lime
resulting from the decomposition of the sulphate of iron will also tend to
prevent the expulsion of ammonia from the sewage water. In making use
of the pieces of lime compound thus prepared I vary my arrangements
according to the nature of the sewage and its comparative freshness. If com-
paratively free from flocculent matter I employ the blocks or pieces as flints
and clinkers are employed in filtration, but if there be reason to fear the
choking of the filters I make use of a series of screens or cases of wicker or
iron work, which will retain the pieces of lime until they are dissolved so as to
allow of the percolation of a portion only of the sewage matter through them,
whilst the main portion passes through narrow channels formed by thescreens,
and these channels are so arranged as to turn the fluid in its passage between
them from side to side, and secure an intimate mingling of the dissolved lime
with the sewage matter.
This arrangement is shewn in the sectional plan view, Fig. 2, in which d
is a tank provided with a vertical perforated screen e, whereby the grosser
fecal matters are arrested and caused to be deposited in the tank d. Part
of the liquid sewage which passes through the screen e will pass straight
through the vertical filters 6, which are constructed in the inanuer shewn in
the enlarged view, Fig. 1, and another part of the sewage will pass in a
serpentine line between the filters, and in so doing will become mixed with
the other portion which has been acted on by the lime compounds in the
filters, so that the whole mass of sewage will be acted upon by the lime
compound. The bed or bottom on which the vertical filters b, b, rest is sloped
downwards towards the tank f in which the precipitate occasioned by the
action of the lime in the filters b, b, is deposited, and may be cleared out
from time to time. A second set of filters g, g, are placed at the further end
of the tank f, and are charged with the metallic salt precipitant. The
distance between the filters band g must depend upon the ordinary condition
of the sewage water. To remove the sulphuretted hydrogen of the effluent
sewage water I prefer using sulphate of irou, because that salt can be pro-
cured at a cheap rate and in the form of crystals, which will admit of the
metallic salt being used in the manner above described in reference to the
use of the picces of lime compound, that is, arranged as a filter or in screens,
or as both combined, in the case of the lime and the iron salt. The filters

page_text: are to be provided with self-feeding hoppers for maintaining the filter beds in
proper condition as the lime and iron salt is washed away.
As regards certain modifications of the first portion of my process above
described, in lieu of milk of lime prepared from fat limes which readily slake
abroad I sometimes propose to use dolomitic limes or a lime compound of
the nature of cements, which latter after calcination will not slake to powder;
but if ground to a powder and mixed in with the sewage water will act to a
certain extent in the same manner, and will give consistency to the sludge
deposits. The latter compounds usually contain iron oxide which, in the
presence of sulphuretted hydrogen, will slowly form sulphide of iron; they
also contain substances useful as manure.
Similar compounds. may sometimes be used in pieces in lieu of the
artificial lime compounds above described to form filters for the sewage
matters.
In forming the artificial pieces of lime compound above described I some-
times mix in ten or fifteen per cent. of sulphate of lime,which will also control
the slaking of the quicklime, or ten or fifteen per cent. of chloride of sodium,
or five to ten per cent. of perchloride of iron, which will render the pieces
more soluble, and will themselves act as disinfectants. Sometimes I add
five to ten per cent. of carbolic acid in manufacturing the pieces on account
of its disinfecting properties.
Instead of employing crystals as sulphate of iron for the second part of the
disinfecting process I sometimes employ a compound of perchloride of iron,
or of sulphate of iron and artificial gypsum made into pieces, which would be
less readily soluble than crystals of sulphate of iron. The beneficial effects of
gypsum as a manure for certain crops is well known, and when the sewage
is to be applied to irrigation the sulphate of lime would be found a useful
adjunct. In the preparation of such pieces of artificial gypsum and irou
salts I merely mix dehydrated sulphate of lime or plaster of Paris with a
solution of the iron salt in the right proportion to make a paste on solidi-
fication. Carbolic acid or chloride of sodium may also be sometimes
advantageously mixed with the paste from which the blocks or pieces of this
compound are to be formed.
Having now described my Invention of improvements in the treatment
and deodorization of sewage water, and having explained the manner of
carrying the same into effect, I claim, as the Invention secured to me by
Letters Patent as aforesaid, treating sewage water first with lime, and after-
wards with metallic salts, as herein set forth.

page_text: Second, I claim preparing lime compounds in a solid form as herein set
forth, for the purpose of applying such compounds for the treatment and
deodorization of sewage water.}
In witness whereof, I, the said Henry Young Darracott Scott, have
hereunto set my hand and seal, the Thirtieth day of April, in the
year of our Lord One thousand eight hundred and sixty-six.
Witness,
FRED. WALKDEN,
66, Chancery Lane.
HENRY Y. D. SCOTT. (L.B.)