IMPROVEMENTS IN THE TREATMENT OF SEWAGE AND IN THE PREPARATION OF MANURES THEREFROM
Year: 1872

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 TREATMENT OF SEWAGE AND IN THE PREPARATION
OF MANURES THEREFROM."
Scaled the 11th February 1873, and dated the 26th August 1872.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his
Petition, on the 26th August 1872.
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 TREATMENT OF SEWAGE AND IN THE
PREPARATION OF MANURES THEREFROM," to be as follows:-
The object of this Invention is the purification of the sewage water
of towns and manufactories, and the extraction therefrom of the
ammonia which they contain in a form available for commercial
purposes.

page_text: either by precipitation or by mere subsidence without chemical assistance;
but I consider the method of precipitation the best. To effect the
precipitation I employ by preference (but I do not limit myself to this
substance) calcined magnesian limestone or dolomite. This compound
I partially dissolve in water (which for economy's sake may be the
clarified sewage water resulting from the precipitation process), and the
lime being more soluble than the magnesia of the compound I am
enabled to run the dissolved lime (with a small proportion only of the
magnesia accompanying it) into the sewage, and thus cause it to pre-
cipitate in a tank, which I will call tank No. 1. The deposit thus
produced I dry and subject to a process of distillation such as is
ordinarily employed in the preparation of charcoal. The products of
distillation I collect for the sake of the tarry and ammoniacal compounds
they contain; and the resulting charcoal will be found to possess in
great intensity the peculiar properties of animal charcoal. The magnesia
obtained from the dolomite is converted into phosphate of magnesia
by any of the well-known processes, and I employ this in conjunction
with the charcoal in the further purification of the effluent liquid from
tank No. 1, and for the extraction of its ammonia.
The phosphate of magnesia and the powdered charcoal prepared as
above described is agitated in tank No. 2 with the effluent sewage from
No. 1, and a great excess of these deodorants is employed so as to insure
that the sewage water shall be well filled with them, and that (to some
extent at least) the perfection of fluid admixtures may be approximated
After sufficient agitation the precipitate formed and the other solid
substances are allowed to subside, and the supernatant water is run into
tank. No. 3.
to.
In tank No. 3 I introduce (into the sewage water) a sufficiency of
milk of lime to precipitate any phosphoric acid which may be carried
away in solution from tank No. 2. I may here again with advantage
employ some of the charcoal, and in certain cases I use the powdered
charcoal in tank No. 3 only, and omit it in tauk No. 2, where I then
use phosphate of magnesia only. After the contents of No. 3 have
been agitated together the precipitate formed is allowed to subside, and
the supernatant water, if it be intended to purify it thoroughly, is passed
through a filter bed of the charcoal; or of the charcoal combined with
other filter beds of gravel, burned ballast, or other suitable substance.

page_text: It will be manifest that in lieu of agitating large quantities of the
phosphate of magnesia and charcoal with the sewage water in tank No. 2,
the effluent sewage may be passed from tank No. 1 through a filter bed
of these substances in order to produce the results aimed at.
Again in lieu of agitating milk of lime with the sewage water in
tank No. 3, the effluent sewage from No. 2 may be filtered through a
filter formed of the calcareous substance produced by the completo
calcination of the deposit from tank No. 1; or again, I may follow another
course. I have only to urge the heat after the distillation process
beyond the temperature required for the proper production of charcoal,
and by the reaction of the carbonic acid in the deposit on the carbon
of the organic matter carbonic oxide is formed and quicklime results.
The compound of charcoal and quicklime thus produced may be
employed for the removal of the phosphoric acid from the sewage from
tank No. 2, either by agitation with it in the powdered form or when
it is used as a filter bed.
In the case of employing the charcoal as a filter I prefer to subject
the deposit from tank No. 1 to heavy pressure before converting it into
charcoal. By this means I impart to the charcoal a density and cohesion
which enables it to be granulated, as is done with ordinary animal
charcoal, for which it may be substituted for a great variety of purposes.
The deposits from tanks Nos. 2 and 3, or the filter beds after they have
lost their properties of absorption and deodorization, may be dried and
be sold for manure, either mixed together or separately. The sulphate of
lime or other compound produced in obtaining the phosphate of magnesia,
may also be added to the deposits from tanks 2 and 3 with advantage in
many cases.
Where also the dry closet system is in use in a town as well as the
method of carrying by water, the charcoal from the deposit may be
employed with advantage as the absorbent. In cases in which long
carriage is necessary in order to dispose of the manure produced, I
distil the ammonia from the deposits in No. 2 and 3 tanks into an acid
solution, or through some other good absorbent or retainer of ammonia,
and I use the recarbonized charcoal over again.
By adding the distilled ammonia to the manure I obtain the manure
in a more concentrated form before sending it into the market.

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 22nd February 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex, 5
Major-General, C.B., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of August, in tho
year of our Lord One thousand eight hundred and seventy-two, in
tho thirty-sixth year of Her reign, did, for Herself, Her heirs and 1
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 Isle
of Man, an Invention for "IMPROVEMENTS IN THE TREATMENT OF SEWAGE AND
IN THE PREPARATION OF MANURES THEREFROM," upon the condition (amongst 2
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, 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, first, the cleansing of the polluted

page_text: organic substances as well as the suspended impurities; and secondly,
the extraction of the fertilizing elements from sewage matters (in
which term I include night soil) in a form available for commercial
purposes.
In carrying out my Invention I vary the details of the method of
procedure according to circumstances, such as the ultimate destination
of the effluent or the demand for the products which can be obtained
from the sewage, and when it is necessary to remove all impurities I
remove them not in one operation but stage by stage.
The general mode of procedure with. liquid sewage consists, first, in
the removal of the grosser impurities (which contain but a small
proportion of its fertilizing elements) by precipitation with lime; ·
secondly, in the conversion of the precipitated matters into charcoal
(by modifying the conditions under which the organic matter is de-
stroyed) when their conversion by complete calcination into agricultural
lime or cement for building purposes (as proposed by me in Letters
Patent, dated Twenty-sixth August, One thousand eight hundred and
seventy-one, No. 2243,) is unadvisable; thirdly, in the extraction of
organic matter and ammonia from the clarified effluent resulting from
the lime process by one or more of the phosphatic precipitants described
by me in Letters Patent, dated Twentieth March, One thousand eight
hundred and seventy-two, No. 849, combined or not with the cleansing
action of the charcoal resulting from the distillation of the lime deposit
obtained under the first head; and, fourthly, in the further removal of
the organic nitrogen and carbon compounds by means of a final filtration
through or agitation with such charcoal, by which means I render the
sewage water sufficiently pure to be run into the smallest streams.
"
The following are the modifications which I introduce according to
circumstances in the above general but complete mode of procedure.
(a.) When the sewage is to be thrown into the open sea at some
distance from a town or into a large river (in which case complete
purification is unnecessary) the first part of the process is alone required.
In this case if cement or mineral manures cannot be manufactured (or
are unsaleable) I convert the whole of the deposit obtained from the
; precipitation in tank No. 1 (in this case the only one) into charcoal to
be employed generally as a disinfecting agent, such as for the cages of

page_text: the man-holes of the town drains, or I may cause it to absorb the
ammoniacal vapours arising from the distillation of other portions of
the sludge, or use it for the deodorizing of cesspools, &c., and finally sell
the compound for manure.
(b.) When the town, village, or place to be dealt with is too small
for a mineral manuro manufactory, and there is no demand for cement
or agricultural lime, though the complete purification of the water is of.
the utmost consequence, I precipitate with limo and dry and roughly
carbonize the resulting deposit in mounds, kilns, or otherwise, and
employ the charcoal so obtained for purifying the water by filtration ]
through filter beds of this carbonized substance alone, or of this substance
mixed with gravel or burned clay; or the carbonized substance may be
spread on the surface of the soil to be used as a filter bed for downward
intermittent filtration.
"¡
"
(c.) When the town is so situated that neither lime nor cement prove 1
readily marketable in the vicinity, but the clarified sewage can be
advantageously employed in farming operations, I precipitate with lime,
convert the deposit into charcoal, and sell or employ the charcoal for
general disinfecting. purposes, as in case (a)..
เ
(d.) When favorable conditions for the preparation of phospliatic
and ammoniacal manure offer themselves, and such manures though
not highly concentrated obtain a ready sale, and agricultural lime and
cement are not in demand, I convert the lime deposit into charcoal
and use it for filtering beds, or stir it with the sewage to be purified as
a powder in combination with one or more of the precipitants described 2
in the before-mentioned Letters Patent, dated Twentieth March,. One
thousand.eight. hundred and-seventy-two, No. 849.
--(e.) When there is a demand for mineral manures, and it is essential
that the manures resulting from the different processes should be as
rich as possible in fertilizing elements,-I-convert-a part only of the lime 3
deposit into charcoal and the remainder into agricultural lime, and I
employ the charcoal in the final purification of the water only after
the noxious. compounds (suspended and in solution in the sewage):
have been as far as possible removed by the various precipitation
processes above referred to..
3

page_text: It will be seen from the foregoing remarks and references that the
chief novelty of the process, so far as I have described it, consists
essentially in the preparation of charcoal from the deposit which is
obtained by precipitating sewage by the lime process, and in using the
3 charcoal so prepared with or without other chemicals, (A) for the
removal of the organic matters from the clarified and partially purified
effluent which results from such lime process, (B) for other disinfecting
and deodorizing purposes.
Having set forth generally the nature of my process, and wherein its
) chief novelty consists, I now proceed to describe in detail the mode of
conducting the operations necessary in such cases as are specified under
heads (d) and (e), which embrace those under heads (a), (b), (c).
"
To effect the preliminary lime precipitation, in lieu of using fat or
pure lime or such meagre limes as the immediate neighbourhood may
5 afford, I employ by preference calcined magnesian limestone or dolo-
mite, and this I do in a manner which I consider to be novel.
Lime being considerably more soluble in water than magnesia I take
advantage of this difference of solubility to effect their separation, and
I employ clarified sewage water pumped back for the purpose as the
) solvent.
The magnesian lime is stirred in suitable vessels with a sufficient
quantity of such water to dissolve out the lime present, and after settle-
ment the supernatant water charged with lime in solution and some
magnesia is run into the raw sewage so as to cause a precipitation in a
tank, which I call tank No. 1. The deposit thus produced I collect dry,
and make into suitable forms for burning, such as bricks or balls. These
are introduced into a double kiln, one compartment of which is employed
in the conversion of the deposit into agricultural lime or cement, and
for supplying the heat which is to effect the carbonization of a second
) portion of the material introduced into the other compartment after the
manner sometimes practised in the preparation of peat charcoal.
The ammonia, tarry matters, and other products of distillation from
the second compartment I sometimes collect by well-known methods,
and at other times I employ them for the sake of the heat generated in
their combustion, for such heat can be utilized for drying fresh portions

page_text: of the deposit. The charcoal thus produced will be found to possess in
great intensity the properties of animal charcoal. Its deodorizing
qualities aro very great, and still more so its properties of decolorizing
liquids. The efficiency of the charcoal would not be injured by the uso
of soluble salts of iron and alumina or other chemicals in conjunction &
with the lime, but any useful purpose they might serve would be moro
than counterbalanced by the increase of cost they would entail upon
the process. It is quite unnecessary that any other precipitant than
lime or any other carbonaceous substance than sewage precipitates
should be used in the production of this peculiar and highly efficient 1
form of charcoal.
The undissolved magnesia which remains behind in the vessels in
which the lime solution is prepared is reserved for conversion (by well
known processes) into phosphate of magnesia, to be employed in the
extraction of the ammonia from the sewage water or for conversion into 1
other salts of magnesia.
The clarified effluent from tank No. 1 is then treated (as is fully
described in the aforesaid Letters Patent, dated Twentieth March,
One thousand eight hundred and seventy-two, No. 849,) with solublo
phosphate of lime or magnesia and hydrated phosphate of magnesia for
the purpose of recovering the ammonia and nitrogen in the sewage
water, or with hydrated phosphate of magnesia only. These phosphato
salts may be either used alone or mixed with the charcoal in the state
of powder prepared from the lime deposit in No. 1 tank, or they may
be used alone and the charcoal be employed as a filtering medium :
between the different precipitations in tanks 2 and 3, referred to in the
aforesaid Patents.
The last plan is that which I prefer to employ when the tanks are of
insufficient size to produce a clear effluent after each precipitation
process, or when the fall is too little to admit of the supernatant water
being drawn off from the different tanks after subsidence of the pre-
cipitated matters. In such cases by employing the charcoal as an
upward filtering medium all the particles of solid matter (either released
from solution or added as precipitants and deodorants) will be retained
in their own compartments, though the flow of sewage be continuous.
When the charcoal after such use is saturated with organic matter it

page_text: may be disposed of as manure, or be revivified by exposure to air or
heat.
For use as manure the intercepted particles of phosphate of lime and
ammoniacal phosphate of magnesia will greatly increase its value. The
nitrogenous matters retained by the charcoal will also add to its fertilizing.
properties.
'
וי
When, as in case (d) large supplies of charcoal are available, and
powdered charcoal is agitated in the sewage water with the phosphate
salts, the mixed deposit obtained may be added to the charcoal removed
from the filtering beds and the compound may be sold as manure. The
powdered charcoal agitated with the sewage water should always be
kept in considerable excess of what is required for the removal of the
organic matter of the charge of sewage at the time acted upon to ensure
that the water may be well scoured by it, or to make up for the want
of fluidity in the charcoal particles. These can of course purify the
water only so far as they come into contact with each atom of it.
:
"
The effluent from tank No. 3, which will contain a certain quantity
of phosphate of magnesia dissolved by the sewage water in its passage
through that tank, is then treated with lime or with dolomitic lime for
case (e), or with lime and charcoal mixed for case (d), and the effluent
is finally purified by filtration through a bed of charcoal prepared from
the same lime deposit. Foul water so treated will be deprived of its
hardness and be fit to be run into any watercourse without injury to
those who may drink of the stream.
The efficacy of charcoal employed in the filtration of sewage water
which has been subjected to the above described operations can be
readily understood.
The lime process applied in tank No. 1 will not only remove the
suspended impurities but will extract from fifty to sixty per cent. of the
dissolved nitrogen. The various precipitations carried out in tanks
Nos. 2, 3, and 4 will reduce the amount of dissolved nitrogenous matter
to a minute quantity; and thus when the water reaches the final
charcoal filtering bed with its active purifying properties unexhausted
by the great contaminating powers of raw sewage, so little clogging of
the pores of the charcoal will take place that it will continue to purify
tho water with scarcely diminished activity for long periods.

page_text: In reference to case (c) it is unnecessary to give any additional details.
Complete purification in that case is neither necessary nor desirable.
Clarification is all that is required as a preliminary to irrigation, and it
would be objectionable to remove more of the fertilizing element of the
sewage water than can be avoided. It will happen however in many
such cases that a large portion of the inhabitants use cesspools or
movable receptacles for the excreta, and throw the kitchen washings, &c.,
only into the drains. In such cases the charcoal derived from the lime
deposit in tank No. 1 comes in as a valuable aid, and may be used as an
absorbent or as a deodorant, and may be made available in conjunction :
with filters of hydrated phosphate of magnesia (as specified by me under
my Patent of Twentieth March, One thousand eight hundred and
seventy-two, No. 849,) in retaining and rendering capable of carriage
the fertilizing clements of the excreta.
By urging the temperature of the kiln (in which the charcoal is :
prepared) to the point at which the carbon of the compound and the
carbonic acid of the carbonate of lime present will react on one another
the production of lime mixed with the charcoal will be the result. This
compound if used with excreta or night soil will effect the decomposition
of the urea of the urine with the production of ammonia, and the ?
retention of the phosphoric acid in solution in the liquid. The ammonia
thus produced will be then absorbed by the filter of phosphate of
magnesia.
In some cases I apply pressure to the deposits from which the

page_text: fertilizing elements contained in sewage matters, and for the manufacture
of manure as herein set forth.
In witness whereof, I, the said Henry Young Darracott Scott, have
horeunto set my hand and seal, the Twentieth day of February, in
the year of our Lord One thousand eight hundred and seventy-
three.
HENRY Y. D. SCOTT. (L.S.)