An Improved Process and Means for the Treatment and Utilisation of Sewage.
Year: 1895

page_text: Date of Application, 14th Feb., 1895-Accepted, 23rd Mar., 1895
COMPLETE SPECIFICATION.
An Improved Process and Means for the Treatment and Utilisation
of Sewage.
I, MARMADUKE FRANCIS PURCELL, of 71 Harcourt Street, Dublin, Ireland,
Barrister-at-law, do hereby declare the nature of this invention, and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
This invention relates to the treatment and utilisation of sewage, such as the solid
matter collected, deposited, or precipitated, from any method of drainage, applicable
to houses, villages, towns, or cities; and consists in the manner of, and means for,
the treatment of the solid residual matter of such sewage, for the purpose of
utilising both the gaseous and solid portions of such sewage by a continuous process,
and the obtaining of commercial products in a manner innocuous to health, and with
the destruction, at the same time, of all organic matter and disease germs.
To carry my process into effect, I take the pressed sludge of such sewage,
preferably after it has been solidified and air-dried by any of the usual methods for
such preparation, and calcine and distil the said pressed sludge in any suitable
internally fired furnace or retort, closed, so as to enable the gaseous products to be
carried away and collected by condensation, where condensible, or otherwise to be
led away and stored for utilisation.
Further, the said furuace or retort is provided with means to enable the calcined
products to be withdrawn from time to time for utilisation as cement, and means
are provided for the supply to the interior of the said furnace or retort of steam,
which may be superheated to a temperature, and of a pressure, adapted, in each
case, to the particular character of the sludge.
To prepare the said furnace or retort for the reception of the sludge, I lay a fire
of any combustible material at the bottom of the furnace, and superpose thereon,
to a small extent, alternate layers of sludge and fuel, as in the case of metal cupola
furnaces, and supply, if necessary, an air-blast until a white heat is set up therein.
After a sufficiently high temperature has thus been obtained the dried sludge may
be continuously added thereto, without further addition of fuel, the combustion of
the organic matter and the chemical combustions hereinafter mentioned, being
sufficient to maintain a white heat at the lower part of the furnace and to effect
destructive distillation in the upper part of the burden. The results of my special
treatment of the dried sludge may be described as follows
By the destructive distillation at the upper part of the furnace a good hydrocarbon
oil will be distilled, as is already known, and may be condensed and collected by
being passed through water. The steam broken up into its constituents of oxygen
and bydrogen by contact with the white hot charge at the lower part of the furnace,
will cause these gases in their nascent condition to combine with other matters
present, the oxygen being serviceable in burning all carbonaceous and organic
matter and the hydrogen aiding largely to combine with the nitrogenous matters
present to form ammonia, and with carbonaceous material, to form carburrette :
hydrogen, thus serving also, by chemical combination, to keep up the heat of the
furnace. The ammonia may be collected and separated from the oils as ammonia
water, by passing through a collecting tank of water, and the non condensible
carburretted hydrogen is stored in a gas holder or in any convenient way for
employment as a source of heat by combustion under steam boilers, or in other
convenient way, or as a source of light when enriched.

page_text: It has been found by direct tests that a very uniform amount of both silica,
alumina, and lime, may be reckoned upon as present in all precipitated sludge
sewage, and these materials with other minerals present in the sewage, when
calcined by the white beat of the lower part of the furnace, and withdrawn, are
found to produce an excellent light coloured cement of commercial value.
A convenient form of apparatus for the carrying out of my said process is shown
annexed hereto in Figure 1.
A is a furnace or retort on a large scale, internally fired at the lower part of the
furnace, and closed by a removable cover B to cause the gaseous products to pass
by the escape pipe C to the water separating tank D. Here the ammonia is taken
up by the water E, the condensible oils F collect on the top of the water, and the
non-condensible gases pass, by the pipe G, to the storage gasometer H. The
accumulated ammonia water, when saturated, and the oil, may be removed by
syphon pipes KK or in other convenient manner.
The lower part of the furnace is closed by sliding shutters L L, by which the
calcined minerals of the charge may be removed from time to time, as it collects,
for utilisation as cement. At the same time, once the furnace has been got up to
white heat continual supplies of fresh sewage sludge may be supplied by trucks M,
or other means, to the furnace, and my process is thus continuous in its action,
and cheaply carried out.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1st. A continuous and complete process for the treatment and utilisation of
sewage sludge by calcination and destructive distillation, induced and maintained
in a closed internally heated furnace or retort by steam jets, upon the white hot
mass of the sewage sludge itself, substantially as described.
2nd. A continuous process for the utilisation of sewage sludge, consisting of the
production simultaneously from the said sludge, by calcination and destructive
distillation, of hydro-carbon oil, ammonia, carburretted hydrogen, and cement,
substantially as described.
3rd. In a process for the treatment of sewage sludge, the production by direct
calcination of the mineral residues of such sludge in a form, adapted to be utilised
as a cement, substantially as described.
4th. In a process for the treatment of sewage sludge, the adaptation of an
internally heated furnace provided with steam jets to the calcination and
destructive distillation of the said sludge, substantially as described.
5th. The means for the carrying out of a process for the treatment of sewage,
consisting, in combination, of the apparatus, substantially as described and
illustrated herewith.
Dated this 12th day of February 1895.
FELL & WILDING,
1, Queen Victoria Street, E.C., Agents for the Applicant.