Improvements in the Treatment of Sewage Sludge to Obtain a Useful Manurial Product therefrom.
Year: 1893

page_text: Date of Application, 16th Nov., 1893
Complete Specification Left, 15th Aug., 1894-Accepted, 10th Nov., 1894
HUVINIONAL OF EUIFICATION.
Improvements in the Treatment of Sewage Sludge to Obtain a
Useful Manurial Product therefrom.
I, JAMES THOMAS DINSDALE, of 100 Upper Thames Street in the City of
London, Chemical Merchant, do hereby declare the nature of this invention to
be as follows:-
1 take sewage sludge in the state in which it is obtained from sewage by filtration
and I mix therewith a mineral acid such as sulphuric acid or it might be an acid
salt; in this way I fix the ammonia and render the sludge innocuous.
Then I pass the sludge into a mixer and there mix with it an earth known as
Kieselguhr. This earth is a powerful absorbent and it reduces the matter to a
state in which it may with convenience be passed through a drying machine. Or
preferably I employ a machine which mixes and dries the materials simultaneously.
I also add to the other materials Kelp salt and it may be other available fertilisers.
The material is discharged from the drier in a powdered state suitable for
transport and for ready application to the land.
Dated this 16th day of November 1893.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Sewage Sludge to Obtain a
Useful Manurial Product therefrom.
I, JAMES THOMAS DINSDALE, of 100 Upper Thames Street, in the City of
London, Chemical Merchant, 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:—
I take sewage sludge in the state in which it is obtained from sewage by
filtration or removal of liquid and I mix therewith a mineral acid such as sulphuric
acid or it might be an acid salt; in this way I fix the ammonia and fertilising
properties and render the sludge innocuous.
Then I pass the sludge into a mixer and there mix with it an earth known as
Kieselguhr. This earth is a powerful absorbent and it reduces the matter to a
state in which it may with convenience be passed through a drying machine. Or
preferably I employ a machine which mixes and dries the materials simultaneously.
I also add to the other materials Kelp-salt and it may be other available fertilisers.
The material is discharged from the drier in a powdered state suitable for
transport and for ready application to the land.
I prefer to operate in the following manner :-
I obtain sludge which has been separated from sewage by simple filtration or
draining without the aid of precipitants for I find that precipitants, such as lime
which is commonly employed, deteriorate the sludge for manurial purposes.
For fixing the ammonia and fertilising properties I usually employ nitre cake
because generally it is more economical than to use sulphuric acid to bring about
the same result.
I grind the nitre cake together with an equal weight of coke. Then in any
suitable way
I mix the sewage sludge which is in a semi-solid state with the
powdered nitre cake and coke. The proportions which I employ are about five

page_text: and a half hundredweight of the powder to the ton of solid material contained
in the sludge. I allow the mixed mass to stand until fermentation begins and
I then pass it into a mixing and drying machine: preferably I employ a machine
in which the material to be dried is passed through a cylinder, containing a
revolving apparatus, entering at one end and being discharged at the other end.
Heat is applied and whilst in the cylinder the material is exposed to a current
of air.
Into this machine I introduce together with the prepared sludge, the absorbent
known as Kieselguhr and also Kelp salt both in a powdered state and in the
proportions of five and three quarters hundredweights of the Kieselguhr and two
and three quarters hundredweights of Kelp salt to the ton of sludge originally
taken.
All these materials are submitted to the action of this machine, and when
sufficiently dried the product which is then in a pulverulent condition is discharged
and allowed to cool. It is then ready for use in agriculture.
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 I
claim is :-
1. The treatment of sewage sludge substantially as herein described by fixing
its ammonia and fertilising qualities with an acid or acid salt, absorbing its
moisture with Kieselguhr, and drying it to a pulverulent condition.
2. A dry pulverulent manure substantially as described and consisting of sewage
sludge in which the ammonia and fertilising properties are fixed, together with
Kieselguhr and with or without other materials.
Dated this 30th day of July 1894.
J. T. DINSDALE.