Improvements in the Production of Gas for Illuminating and Heating Purposes, and of certain Bye-products.
Year: 1897

page_text: Date of Application, 2nd Sept., 1897
Complete Specification Left, 20th May, 1898-Accepted, 16th July, 1898
Improvements in the Production of Gas for Illuminating and Heating
Purposes, and of certain Bye-products.
I, WILLIAM DANCER, of 466, Chester Road, Old Trafford, near Manchester, in
the County of Lancaster, Analytical Chemist, do hereby declare the nature of this
invention to be as follows:-
My said invention relates to improvements in the production of illuminating
and heating gas, and certain bye products.
The object of my invention is to utilise sewage sludge or precipitate, which is
obtained in the treatment of sewage with lime, sulphate of alumina, sulphate of
iron or other substance to effect the precipitation of the solid matter held in solution
and suspension in the sewage.
In carrying my invention into effect I first dry the sludge or precipitate. This
may be conveniently and economically effected by means of the waste heat evolved
from refuse destructors or the like. The dried sludge is then distilled in an
ordinary gas retort, the gas thereby distilled being purified in the usual way and
collected in a gas holder.
I have found by experiment that sewage contains a large portion of oily or fatty
matter which is precipitated by the lime or other substance used to effect precipita-
tion, carrying with it the organic matter present in the sewage which being
decomposed by distillation produces a gas fit for illuminating and heating:
purposes.
In addition to the production of gas, valuable bye products are obtained such as.
ammonia resulting from the decomposition of the nitrogenous matter, the. residue
in the retort may also be again used to effect precipitation of the sewage or for
other purposes.
Improvements in the Production of Gas for Illuminating and Heating
Purposes, and of certain Bye-products.
I, WILLIAM DANCER, of 466, Chester Road, Old Trafford, near Manchester, in
the County of Lancaster, Analytical Chemist, 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 that is to say:
My said invention relates to the treatment of the sewage sludge or precipitate

page_text: obtained from sewage by treatment with minerals or salts, such as lime, sulphate
of alumina, sulphate of iron or the like.
Hitherto the sewage sludge has been regarded as practically worthless. I have
found however by experiment that the action of the substances used to effect
precipitation of the solid matter held in solution and suspension in the sewage, is
mainly to form an insoluble soap or compound of the fatty acids contained in the
sewage with the oxide of metal used for precipitation.
The precipitant most generally in use is lime or milk of lime, being considered
the best and cheapest, and in this case the precipitate produced is a lime soap
which is practically insoluble in water and which carries down with it the organic
and inorganic matter in suspension along with part or all of the uric acid and
phosphoric acid in solution in the sewage.
The object of my invention is to utilize the sewage sludge and convert it into
gas, ammonia and other bye-products.
In carrying my invention into effect I first dry or partially dry the sludge or
precipitate. This may be conveniently and economically effected by means of the
heat evolved from refuse destructors or any other source of waste heat.
-
The dried sludge is then put into an ordinary gas retort and subjected to
distillation at a high temperature by which means I obtain a direct conversion
into gas and ammonia, together with a small proportion of undecomposed oil.
To effect the most complete decomposition I prefer to use two retorts, the second
retort containing red hot coke or other inert substance so that any oil which may
distil over from the first retort is at once converted into gas on coming into contact
with the heated substance in the second retort. The gas so produced is mainly
what is known as oil gas and it may be purified in the usual way. The ammonia
carried over with it is separated by washing as in the case of the ordinary working
of coal gas.
The residue in the retort where lime has been used as a precipitant is of some
value as a manure on account of the lime and phosphate of lime which it
¿contains.
Where minerals or salts other than lime, such as sulphate of iron are used to
effect precipitation of the sludge, the residue in the retort may also be used for
the purification of coal gas or for other purposes.
Another method of treating the sewage sludge is to distil the same at a lower
temperature in large retorts similar to those used in Scotland in the manufacture
of shale oil. This method would be most suitable where large quantities of sewage
sludge have to be disposed of, and where the gas cannot be used for illuminating
purposes, as for instance in places where the producers of sludge are not also gas
manufacturers. In this method oil is distilled off at a low temperature, which
oil could afterwards be made into gas in the ordinary method of oil gas manu-
facture, and any gas given off by this process of distilling oil at a low temperature
could, after recovery of ammonia, be used in place of fuel for heating the retorts
as it is at present done in shale oil works.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
The manufacture or production of gas, ammonia and other bye-products from
sewage sludge in the manner and substantially as described.
Dated this 10th of 1000
Doted this 10th day of May 1908.
For the Applicant,
E. K. DUTTON & Co.,
:
Chartered Patent Agents, 5, John Dalton Street, Manchester: