IMPROVEMENTS IN TREATING SEWAGE WATER TO OBTAIN VALUABLE PRODUCTS THEREFROM
Year: 1876

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lane, in the County of
"
Middlesex, Patent Agent, for the Invention of IMPROVEMENTS IN TREATING
SEWAGE WATER TO OBTAIN VALUABLE PRODUCTS THEREFROM." A commu-
nication from abroad by Clovis Knab, de la Société Générale d'épuration
et d'assainissement des Villes, of Paris, France.
Sealed the 28th October 1876, and dated the Sth May 1876.
PROVISIONAL SPECIFICATION left by the said William Clark at the Offico
of the Commissioners of Patents on the Sth May 1876.
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. "IMPROVEMENTS IN TREATING SEWAGE WATER TO OBTAIN VALUABLE
PRODUCTS THEREFROM."
This Invention relates to improvements in the treatinent of sewage waters for
recovering either the whole or a portion of the soluble salts contained, and the
whole of the manure in a solid form. This result is obtained by following the
two methods herein-after described.
According to the first method, the impure liquid is first treated directly on its
reaching the sewer with an acid, and preferably with sulphuric acid, which instantly
fixes the aminonia in the state of sulphate. The quantity of acid employed depends
upon the proportion of ammonia contained in the liquid, in some cases from 28 to
38 lbs. of acid being required per cubic metre of liquid. 2nd. The mud or slime
contained in the sewage water, and in which ammonia is also fixed, is next separated
by decantation. 3rd. The acidified clarified liquid is evaporated in a vacuum
apparatus ("triple effect ") similar to those of sugar refineries, whereby a concen-
trated solution of salts is obtained, marking 30 to 35 degrees Baume. 4th. This
concentrated solution is passed through a filter press to remove the residuum of
mud which always forms, during the concentration, and which is added to that
retained by filtration. 5th. The filtered liquor is then crystallized, either in n
vacuum or in an open boiler, heated either by a steam coil or ordinary furnace.
In the latter case by stirring continually the liquor may be evaporated to the con-
sistency of and in cooling the salts combine in a hard crystalline mass.
syrup,
The salts are dried on iron plates by the waste heat of the apparatus, and are then
[Price 4d.1
Gth.

page_text: ground and put up in barrels. These salts contain all the elements of acidified
sewage water, that is, ammonia salts, soluble phosphates, salts of potash, and soda
and others, and in fact form a perfect manure of great richness, and more especially
rich in nitrogen. The evaporated and condensed liquid which remains is very
clear and transparent, and being perfectly innocuous may be discharged into the
sewer. 7th. The mud or sludge from the clarifying apparatus is then treated apart
in large metal reservoirs, heated by steam to 212, to coagulate the albuminous
matters, adding from 4 to 10 per cent. of natural phosphate in powder, or, pre-
ferably, phosphate of lime precipitated chemically. The boiling mixture is then
passed to a filter press, from which the water is allowed to drain, the manure being
retained in the form of cakes in a nearly dry condition. The matters may even
be pressed without the addition of the phosphate, but with greater difficulty, and
the phosphate also serves to enrich the manure. The matters may be obtained in
a still drier condition by first filtering the boiling mass through canvas, and then
pressing by hydraulic power as in ordinary. The water of filtration is returned to
the evaporator ("triple effect"), and the cakes, after being exposed to the air for
some time, are ground up and form an excellent manure containing the whole of
the organic nitrogen, and that in the state of salt of phosphate of lime obtained
from the sewage water and from that which has been added, the quality of the
manure being superior to that of ordinary desiccated night soil.
The second method of this Invention for the treatment of sewage water consists
in treating the same without decanting in closed chainbers with a sufficient
quantity of milk of lime to absorb the carbonic and sulphuric acids and saturate
the soluble phosphates, after which the the "triple effect"apparatus is used simply
to drive off the ammoniacal gases, for which purpose the arrangement is considerably
modified, that is to say, the water to be treated, instead of being introduced into
the smallest evaporator and passed successively by exhaustion into the next smaller
vessel, and then into the one in which the evaporation is completed, is, on the
contrary, first introduced into the largest vessel, and ultimately passes into the
smallest of the series, whence it is discharged, freed of all ammoniacal vapors; and
in order that the water may thus circulate, notwithstanding that the vacuum is
greater in the largest vessels, I dispose the three vessels at different levels, instead
of in the same line, the variation in the level being so calculated as to overcome
the difference in the vacuum. As in this instance it is only the ammonia gas which
is evaporated and not the whole of the water, instead of employing steam for
heating by its contact with metallic surfaces, 1 simply inject the same into the
liquid through open tubes, so as to agitate the same. By this method the whole
of the heat is utilized and incrustations are prevented. The mud or sludge
contained in the liquid causes no inconvenience. By this 2nd method above-
described three products are also obtained, viz-1st. Sulphate of ammonia product
of the condensation of ammonia gas in a closed bath of sulphuric acid. The vessel
containing this bath communicates with the pump, by which the vacuum is main-
tained, and which should be more effective than when the whole of the liquid is
evaporated, as in the first method described. 2nd. Slimes, rich in manure, which
are separated by filtration and pressure, the residue containing the whole of the
phosphate in the sewage water and the whole of the organic nitrogen. 3rd. Un-
distilled water, but clear and containing only salts of potash and soda, whose value
does not, however, equal the saving in fuel realised by this second method.
The presence of lime in the manure is not a disadvantage, as when combined it
will no longer drive off the nitrogen. I may, however, first decant the liquid to
extract the mud or sludge and treat it in a heated state, and then acidify as in the
first method described, treating with lime this decanted liquor only.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Clark in the Great Seal Patent Office on the 7th November
1876.
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. "IMPROVEMENTS IN TREATING SEWAGE WATER TO OBTAIN VALUABLE PRO-
DUCTS THEREFROM." A communication from abroad by Clovis Knab, de la Société
Générale d'epuration et d'assainissement des Villes, of Paris, France.
This Invention relates to improvements in the treatment of sewage water for extract-
ing either wholly or partially the soluble salts and the whole of the solid manure con-
tained. This result is obtained by following the two methods herein-after described.
According to the first method, the impure liquid is first treated directly on reaching
the place of deposit with an acid, preferably sulphuric acid, which instantly fixes the
aminonia in the form of sulphate. The quantity of acid employed depends on the
proportion of ammonia contained in the liquid. At the sewage depot at Bondy, near
Paris, from 28 to 38 lbs. of acid are required by cubic metre of liquid. 2nd, the mud
or slime contained in the sewage water and in which ammonia is also fixed is next
separated by decantation. 3rd. The acidified clarified liquid is evaporated in a set of
triple effect vacuum pans, similar to those of sugar refineries, whereby a concentrated
solution of salts is obtained marking 30 to 35 degrees Baumé. 4th. This concentrated
solution is passed through a filter press to remove the residuum of mud, which always
forms during the concentration, and which is subsequently added to that retained
by the decantation. 5th. The filtered liquor is then crystallized either in vacuo or
in an open boiler heated either by a steam coil or ordinary furnace. In the latter
case by stirring continually the liquor may be evaporated to the consistency of syrup,
and on cooling the salts collect in a hard crystalline mass. 6th. The salts are dried on
iron plates by the waste heat of the apparatus, and are then ground and put up in
barrels. These salts contain all the elements contained in the acidified sewage water,
that is to say, the ammoniacal salts, the soluble phosphates, and the salts of potash
and soda, &c., and in fact form a perfect manure of great richness,especially in nitrogen.
The evaporated and condensed liquid which remains is very clear and transparent,
and being perfectly innocuous inay be discharged into the nearest sewer.
mud or sludge separated by decantation as above mentioned is then treated apart
in large sheet iron reservoirs, heated by steam to 212°, to coagulate the albuminous
matters with the addition of from 4 to 10 per cent. of natural phosphate in powder,
or, preferably, phosphate of lime precipitated chemically. The boiling mixture is
then passed to a filter press, from which the water is allowed to drain, the manure
being retained in the form of cakes in a nearly dry condition. The matters may
be pressed, but with greater difficulty, without the addition of the phosphate
which, moreover, serves to enrich the manure. The matters may be obtained
in a still drier condition by first filtering the boiling mass through canvas and
pressing the residuum by hydraulic power as in ordinary. The water of filtration
is returned to the triple effect evaporator, and the cakes, after being exposed to the
air for some time, are ground up and form an excellent manure containing the whole
of the organic nitrogen, nitrogen in the state of salt of the phosphate of lime from
the sewage water and that which has been added, the quality of the manure being
superior to that of ordinary poudrette or desiccated night soil. The sewage matter
is thus converted into three products, viz, pure distilled water, salts of great richness
for agricultural purposes, and a rich manure in cakes.
7th. The
The second method of this Invention for the treatment of sewage water consists
in treating the same without decanting in closed chambers with a sufficient quantity
of milk of lime to absorb the carbonic and sulphuric acids and saturate the soluble
phosphates, after which, instead of completely evaporating the water, the "triple
effect" apparatus is used simply to drive off the ammonia gas, in which case the
arrangement is considerably modified, that is to say, the water to be treated instead of
being introduced into the smallest evaporator and passed successively by exhaustion
into the medium, and then into the largest vessel in which the evaporation is com-

page_text: pleted, is, on the contrary, first introduced into the largest vessel, and ultimately passes
into the smallest of the series, whence it is discharged, freed of all ammoniacal vapors;
and in order that the water may thus circulate, notwithstanding that the vacuum is
greater in the two larger vessels, I dispose the three vessels at different levels instend
of being all at the same height, the difference in level being sufficient to overcome
the difference in the vacuum. As in this case only the ammonia gas is to be driven
off, and not the whole of the water, instead of using steam heated coils or surfaces I
simply convey the steam into the liquid through open tubes, from which the steam
escapes and bubbles through the liquid. By this method the whole of the heat is
utilized and its transmission is no longer obstructed by incrustation, neither does the
mud or sludge contained in the liquid cause any inconvenience. By this 2nd method
above described three products are also obtained, viz. -1st. Sulphate of ammonia pro-
duct of the condensation of the ammonia gas in a closed bath of sulphuric acid. The
vessel containing this bath communicates with the pump by which the vacuum is
maintained and which requires to be much less powerful than when the whole of
the liquid is evaporated, as in the first method described. 2nd. Rich manure sludge
separated by filtration and pressure, the residue containing the whole of the
phosphate of the sewage water and the whole of the organic nitrogen. 3rd.
Undistilled water, but still clear and containing only salts of potash and soda
whose value does not, however, equal the saving in fuel realised by this second
method.
The presence of lime in the manure is not a disadvantage, since being combined it
will no longer drive off the nitrogen, I, however, reserve the right of decanting the
liquid to extract the mud or sludge (which I treat with heat and acid as in the first
method described), and treating with lime this decanted liquor only.
Having described the nature of the said Invention and the manner of per-
forming the same, I declare that what I claim as the Invention to be protected by
the herein-before in part recited Letters Patent is, the processes or methods of treating
sewage water herein described to extract the soluble salts as well as the whole of tho
solids it contains as specified.
In witness whereof, I, the said William Clark, have hereunto set my hand
and seal, this Fourth day of November, in the year of our Lord One thousand
eight hundred and seventy-six.
W CLARK. (L.S.)