Improvements in the Treatment of Sewage Sludge and the Preparation of a Manure therefrom.
Year: 1886

page_text: Date of Application, 19th May, 1886.
Complete Left, 16th Feb., 1887.
Complete Accepted, 18th Mar., 1887.
RES:
Improvements in the Treatment of Sewage Sludge and the
Preparation of a Manure therefrom.
I THOMAS HENRY COBLEY of Victoria Street, Dunstable, in the county of Beds,
Manufacturing Chemist do hereby declare the nature of this invention to be as
follows:-
I
This invention relates to improvements in treating sewage sludge for the manu-
facture of an improved fertilizing material which I term Fecal Guano and the
improvements consist in the employment of the ash of incinerated or burni sewage
sludge as a substitute for the lime now employed for the purpose of pressing the
sludge whereby I economise cost and increase the value of ile ash for after use:
also introduce salts of magnesia potash and soda during the process of burning or
incineration in order to fix by the acid fumes from the decomposing salts, the escaping
gases leaving the bases in the ash and I use an absorbent for the nitrogenous
(ammoniacal vapours given off during the process of incineration or burning.
In carrying out my invention the deposit from sludge or treated sewage is mixed
with the ash produced from the burning or incineration of such sludge in such
proportion that it should form ten per cent more or less of the cake when pressed.
the ash is stirred well into the sludge so as to get it thoroughly mixed and then
pumped into the presses precisely in the same manner as though lime were used.
I also mix peat dust or bone ash with the ash under certain conditions that is to say
where the object is to produce a special quality of fertilizer.
The pressed cake is then removed to the burners or incinerating ovens and during
the charging a certain proportion of salts of magnesia, potash and soda are
introduced, sprinkled or strewn in, equal to two per cent more or less of the weight of
the cake.
The salts I find it advantageous to use for this purpose are, Kainite, Kieserite and
Common Salt or admixtures of the same.

page_text: In order to provide organic matter to replace that driven off by the combustion I
use a mixture of peat dust and sulphuric acid the quantity of acid being just
sufficient to moisten the peat dust; this mixture serves as an absorbent for the
nitrogenous (ammoniacal) gases given off during the combustion of the cake.
required this mixture may be partially or wholly neutralised by the addition of
phosphate of lime in a powdered state.
If
The ash produced as above described from the sewage sludge is mixed in varying
proportions with the sulphatised or ammonuiretted organic matter whereby I obtain a
valuable manure which I term Fecal Guano,
G. F. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicant.

page_text: Improvements in the Treatment of Sewage Sludge and the
Preparation of a Manure therefrom.
I THOMAS HENRY COBLEY, of Victoria Street, Dunstable, in the county of Bedford,
Manufacturing Chemist do hereby declare the nature of this invention and in what
manner the saine is to be performed to be particularly described and ascertained in
and by the following statement :-
This invention relates to improvements in treating sewage sludge for the manu-
facture of an improved fertilising material which I term Fecal Guano and the
improvements consist in the employment of incinerated or burnt sludge ash as a
substitute for lime now employed for the pressing or dehydration of the sludge
whereby I economise cost and increase the value of the ash for fertilising purposes,
also the introduction of native salts of magnesia potash or soda (Kainite or Kieserite)
during the process of burning or incineration in order that the fumes given off from
the decomposing salts of an acid nature may fix or combine with the ammoniacal
(nitrogenous) vapours likewise produced during the process of incineration, the bases
of such decomposing salts being afterwards combined with the ash.
I also employ an absorbent for recovering any volatile matters in addition to the
use of the above salts.
In carrying out my invention 1 proceed as follows:-
Where the object is to economise the lime in pressing then the ash I employ is that
from a sludge which has been precipitated by the aid of lime and the ash selected
containing as much caustic lime as possible that is burned at a high temperature
finely sifted so as to free it as much as possible from silicious detritus; this is added
to the sludge in such proportion that it should form about ten per cent more or less
of the cake when pressed. The prepared ash is thoroughly admixed with the sludge
and then pressed in the ordinary manner in filter presses but I do not confine myself
to the use of filter presses as any other suitable mode of dehydrating the mass the
use of the ash as a dryer is equally applicable when the sewage mass is intended to be
used as a fertiliser.
Where the sludge has not been precipitated by the aid of lime, instead of using
the burnt sludge ashes I employ ashes rich in lime such as the ashes from worthless
calcareous phosphates or the ashes of phosphatic slags so as to increase at the same
time the percentage of phosphate. The proportions in which these ashes or slags
hereinbefore referred to should be employed as a substitute for the burnt sludge ash
will much depend upon the amount of free lime contained in them and should form
about 15 per cent more or less of the cake when pressed.
The pressed cake or dehydrated mass is then removed to suitable furnaces for
incineration, and during the process of incineration I introduce into the furnace
native salts of magnesia potash and soda, such as Kainite or Kieserite but this is
done at an early stage of the incineration; the selection of the salt will depend upon

page_text: the quality of the fertiliser required, that is to say, whether potassical or magnesian.
The proportions should be about two and a half per cent of native salt, more or less
per weight of pressed cake; this is the very lowest percentage to be of any practical
use in the manure. Where much lime is present in the cake the salts must be burnt
as much as possible out of contact with the cake in a corner of the furnace where, it'
can be mixed with ash afterwards as required otherwise a greater portion of the acid
fumes given off from the burning salts will be fixed by the lime.
The object of burning these salts during the incineration of the sludge is to
produce acid fumes so as to combine with the nitrogenous ammoniacal vapours given
off from the incinerating sludge.
In addition to this mode of dealing with the volatile matters cause them to pass
through an absorbing material such as peat dust, such peat dust being selected which
contains the largest amount of nitrogen or I employ any other porous substance
containing nitrogen such as shoddy or wool dust these substances to be impregnated
with a solution of superphosphate of lime or where no salts are burned then with
sulphuric acid or other convenient chemical agent and kept moistened by the
introduction of steam.
The incinerated sludge ash with the calcined salts and the absorbing mass (after
passage of the gases) are then mixed and ground up together to form the fertiliser
which I term Fecal Guano.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed declare that what I claim is
1. In the manufacture of what I term fecal guano the use as described of lime
substitutes for pressing and dehydrating sewage sludge and improving its condition
for fertilising purposes substantially as hereinliefore described.
2. In the manufacture of what I term fecal guano the employment of native salis
as described capable of being decomposed by heat and giving off acid fumes for
the purpose of combining with and fixing the volatilising ammoniacal vapours
given off in the process of incineration of the sewage sludge substantially as herein
described.
3. The use of a prepared absorbent (other than native salts) for collecting or
absorbing any volatile matters escaping from the incinerated sewage sludge in the
preparation of the fertilising material which I call fecal guano substantially as herein
described.
4. The combination of the various products herein named with the incinerated ash
of sewage sludge for the production of a special manure which I term fecal guano
substantially as described.
G. F. REDFERN,
4, South Street, Finsbury, Lon lon,
Agent for the Applicant.