Improvements in the Treatment of Sewage.
Year: 1898

page_text: 0
Date of Application, 23rd May, 1898
Improvements in the Treatment of Sewage.
We, FRANCIS MUDIE SPENCE and DAVID DICK SPENCE, both of the Manchester
Alum Works, Manchester, in the County of Lancaster, Manufacturing Chemists,
do hereby declare the nature of this invention to be as follows:-
This invention consists in improvements in the treatment of sewage, in which
term we include other similar liquids containing putrescible excrementitious sub-
stances and soapy or fatty matters.
Many towns discharge sewage of such a character that after its putrescible sub-
stances have been precipitated in tanks by aluminoferric it yields an effluent
which on being used for irrigation tends to clog or choke up the land. Careful
investigation and experiment have shown us that in such cases the sewage is so
highly alkaline that the sulphuric acid of the precipitant is not sufficient in
amount to neutralise all the soda of the sewage; that the effluent thus contains
soapy or fatty matters; and that it is these soapy or fatty matters which tend
to cause the clogging up of the soil.
Our invention has for its object :-
(a). The production of a tank-effluent which being bright, clear, neutral and
practically speaking completely free from fatty matters, may be applied as a liquid
fertiliser to irrigable land year after year without any fear of clogging it up.
(b). The recovery of the fatty matter from the sewage.
(c). The production of a better manure than that hitherto produced from the
putrescible matter of sewage.
According to this invention we treat sewage either with aluminoferric or
aluminic sulphate or ferric sulphate but preferably with aluminoferric, and
also with sulphuric acid, in such proportions that the alkalinity of the liquid is
completely neutralised and the fat or fatty acid of the soapy or fatty matters is
precipitated along with the putrescible matter.
The clear liquid or effluent is then by any suitable means separated from the
precipitated portion or sludge.
i
The precipitated portion or sludge is freed by pressing and drying or by any
other suitable means from the greater part of the liquid associated with it. The
dried sludge is then treated in a suitable vessel or suitable vessels with ether or
bisulphide of carbon or petroleum spirit or with any other suitable solvent or
solvents with the object of dissolving out the fat, fatty acid or fatty acid com-
bined or associated with aluminic or ferric oxide, contained in such dried sludge.
The resultant liquid, consisting of the solvent or solvents used, and the fat,
fatty acid or fatty acid combined or associated with alumina or ferric oxide dis-
solved therein, is then separated by filtration or otherwise from the insoluble solid
portion. The fat, fatty acid, or fatty acid combined or associated with alumina
or ferric oxide dissolved in such liquid is then separated from the solvent or sol-
vents by distilling off the solvent or solvents or by any other suitable means which
will enable the solvent or solvents to be recovered for further use.

page_text: The alumina or ferric oxide which is combined or associated with the fatty acid
we dissolve out from the latter with dilute sulphuric acid, thus obtaining a
portion of precipitant for further use, and the fat or fatty acid may then be utilised
either in the form in which it is left after being freed from such precipitant or
after it has been subjected to further purification.
The portion of the sludge which was insoluble in the solvent or solvents above
referred to contains phosphoric acid and nitrogenous matter and after drying it in
any suitable way we utilise it as a manure. Unlike the dried sludge produced by
precipitation from a highly alkaline sewage without neutralisation, which con-
tains a portion of fatty acid in combination with the lime originally present in
the sewage, the dried sludge obtained by our process is free from fatty matter.
The effluent, freed as above described from fatty matter and containing all the
valuable nitrogenous constituents of the sewage which were not precipitated in
the sludge, is now in the very best condition for application to irrigable land in
large quantities year after year without any tendency to clog or choke it up.
Our process applies only to alkaline sewages containing more alkali than can
be neutralised by the sulphuric acid present in the aluminoferric or aluminic
sulphate or ferric sulphate required to precipitate their putrescible matter.
Dated this Twenty first dose of May 1808
HOWARD
CHEETHAM,
Manchester, Agent to the Applicants.
Improvements in the Treatment of Sewage.
We, FRANCIS MUDIE SPENCE and DAVID DICK SPENCE, both of the Manchester
Alum Works, Manchester, in the County of Lancaster, Manufacturing Chemists,
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 follow-
ing statement:-
This invention consists in improvements in the treatment of sewage, in which
term we include other similar liquids containing putrescible excrementitious sub-
stances and soapy or fatty matters.
According to this invention we treat sewage with ferric sulphate, and also
with sulphuric acid, in such proportions that the alkalinity of the liquid is com-
pletely neutralised as indicated by methyl orange in the way well known to
chemists, and the fat or fatty acid of the soapy or fatty matters is precipitated
along with the putrescible matter. We find that from 10 to 20 cwts. of ferric
sulphate, and about 12 to 18 cwts. of sulphuric acid of a specific gravity of 17 are
suitable quantities for the precipitation and neutralisation of a million gallons of
ordinary town sewage but the quantity of each material required necessarily varies
with the degree of impurity and of alkalinity of the sewage as ascertained by tests
from time to time. The ferric sulphate may be used either in the form of slabs or
lumps placed in the conduit delivering the sewage into the precipitating tanks,
or in the form of a regulated stream of the material in solution made to run into
the conduit. The acid may be delivered in the form of a regulated stream near
the point at which the ferric sulphate is supplied. After the addition of the
ferric-sulphate and the sulphuric acid the clear liquid or effluent is then by any
suitable means separated from the precipitated portion or sludge.

page_text: The precipitated portion or sludge is freed by pressing and drying or by any
other suitable means from the greater part of the liquid associated with it. The
dried sludge is then treated in a suitable vessel or suitable vessels with ether or
bisulphide of carbon or petroleum spirit or with any other suitable solvent or
solvents with the object of dissolving out the fat or fatty acid contained in such
dried sludge.
The resultant liquid, consisting of the solvent or solvents used, and the fat
or fatty acid dissolved therein, is then separated by filtration or otherwise from
the insoluble solid portion. The fat or fatty acid dissolved in such liquid is then
separated from the solvent or solvents by distilling off the solvent or solvents or by
any other suitable means which will enable the solvent or solvents to be recovered
for further use.
The fat or fatty acid may then be utilised for any purpose for which it may
be suitable either in the form in which it may be after separation from the solvent
or after being subjected to any process of purification which may be requisite such
for instance as that of distillation in a current of superheated steam.
The portion of the sludge which was insoluble in the solvent or solvents above
referred to contains phosphoric acid and nitrogenous matter and after drying it in
any suitable way free from the solvent or solvents and taking care to recover the
latter for further use, we utilise such insoluble portion as a manure. Unlike the
dried sludge produced by precipitation from a highly alkaline sewage without
neutralisation, which contains a portion of fatty acid in combination with the
lime originally present in the sewage, the dried sludge obtained by our hereinbefore
described process is free from fatty matter and is thus not only enriched in phos-
phoric acid and nitrogenous matter but is freed from a manurially injurious
constituent.
The effluent, freed as above described from fatty matter and containing all the
valuable nitrogenous and other fertilising constituents of the sewage which were
not precipitated in the sludge, is now in the very best condition for application to
irriable land in large quantities year after year without any tendency to clog
or choke it up the land at the same time through its well-known action in with-
drawing fertilising constituents from solution, still further purifying the effluent.
As the purified and defatted effluent produced by our process contains sufficient
nitrogenous constituents to bring its potential value at present prices for sulphate
of ammonia to about nine pounds sterling per million gallons those local authorities
who do not find in the recovered fat and the defatted manure a sufficient induce-
ment to utilise their sewage instead of virtually destroying it by bacterial pro-
cesses are now by our invention supplied with a much stronger motive to do so;
and even those authorities who have no irrigable land in their immediate neigh-
bourhood will now be enabled to utilise their sewage by passing it through pipes
to districts at a considerable distance the outlay for the pipes being recouped by
the value of the produce obtained from the irrigating effluent.
Our process applies only to alkaline sewages containing more alkali than can be
neutralised by the sulphuric acid present in the ferric sulphate required to pre-
cipitate their putrescible matter.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:
1. The hereinbefore described process for the treatment of sewage whereby con-
currently with its purification from putrescible matter and fat or fatty acid, the
fat or fatty acid is obtained from it substantially as described.
2. The herein before described process for the treatment of sewage whereby con-
currently with its purification from putrescible matter and fat or fatty acid, a
defatted manure is obtained from it substantially as described.
3. The hereinbefore described process for the treatment of sewage whereby
concurrently with its purification from putrescible matter and fat or fatty acid

page_text: there is obtained from it a clear, neutral effluent containing all the valuable
fertilising constituents of the sewage not-precipitated in the sludge and therefore
specially suitable for application in large quantities to irrigable land year after
year without any fear of ever clogging or choking up the latter. -
Dated this Twenty-second day of Wolruary 1899
HOWARD CHEETHAM,
Manchester, Agent to the Applicants.