Year: 1887

page_text: Date of Application, 3rd Feb., 1887
Complete Left, 3rd Nov., 1887
Complete Accepted, 6th Dec., 1887
I DAVID CRAIG, of 10, Bridge Street, Bradford Arms, Shipley, in the County of
York, do hereby declare the nature of this invention to be as follows:-
The object of this invention is to utilise sewage sludge, or the matter deposited during
the process of purifying sewage; and it consists in distilling such sludge for the purpose
of producing illuminating gas, and certain other gases, and residuary substances.
To carry out my invention I allow the sludge to become comparatively dry by
exposure to the atmosphere, and then place it in a suitable drying apparatus preferably
heated by steam until thoroughly dry. I then treat the dried sludge in a somewhat
similar manner to the treatment of coal for the production of ordinary gas. The
sludge is placed in a retort and on the application of heat thereto illuminating gas is
evolved in combination with ammonia gas, carbonic acid gas, and certain other gases
the proportion of which vary according to the nature of the sludge operated on. Suitable
means are used, to purify the gas or separate the noxious and uncombustible gases,
preferable in a manner consistent with their employment for other purposes. The
residue and tarry matters are also treated for the production of certain by-products.
Noted this 2nd day of February 1887
DRACUP & NOWELL,
Bradford, Agents.

page_text: I, DAVID CRAIG, of 10, Bridge Street, Bradford Arms, Shipley in the County of
York, 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:
The object of this invention is to utilise the matter deposited during the
purification of sewage, commonly known as sewage sludge, and it consists in
distilling such sludge for the purpose of producing illuminating gas and certain other
gases and residuary substances.
To carry out my invention I preferably allow the sludge to be operated upon to
become comparatively dry by exposure to the atmosphere or the bulk of the water
may be removed by means of a filter-press it is then subjected to a dry heat, preferably
in a suitable apparatus heated by steam, until thoroughly dry. I then treat the dried
sludge in a similar manner to the treatment of coal for the production of ordinary
illuminating gas. The dry sludge is placed in a retort of similar construction to an
ordinary gas retort and on the application of heat thereto illuminating gas is evolved
in combination with ammonia, sulphuretted hydrogen, and carbonic acid gas, the
proportions of which vary according to the nature of the sludge operated on. Similar
means are employed for purifying the gas, or separating the noxious and incombustible
gases from the illuminating gas and for utilising such gases for other purposes, as are
used when coal gas is made. And during distillation certain tarry matter is evolved
which is also similarly treated.
The residue after distillation consists chiefly of mineral matter and carbon and may
be used to fertilise land.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed I declare what I
claim is :
The production of illuminating gas by the distillation of sewage sludge, substantially
as herein described.