Year: 1887

page_text: We, JOSEF WOHANKA, and KARL KOCIAN, both of the firm of Wohanka and Co.,
of Prague, in the Empire of Austria, Merchants and Manufacturers, 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 :-
Our invention relates to an improved process of purifying and rendering innoxious
the refuse water of manufactories the drainage and contaminated water of houses, and
other kinds of sewage.
The improved process comprises two principal operations, viz.-first the successive
treatment of the sewage with ferric sulphate, with lime milk mixed with iron ochre,
and with an aqueous solution of water glass, the precipitate being afterwards separated
from the liquid by decantation; and second the treatment of this partly purified liquid
by means of smoke gases or the like, for the purpose of extirpating any organism or
organic germs existing in the liquid, and precipitating the impurities, which
may not
have been removed by the first operation by depositing crystalline carbonate of lime,
caustic lime being subsequently added with the object of restoring a certain alkalinity
to the purified water.
The process is carried into practical effect as follows;-
Natural ferric hydrate (preferably rich iron ochre-brown iron ore) is treated with
sulphuric acid, whereby a solution of ferric sulphate is obtained. This solution is
thoroughly mixed with the sewage to be purified. Freshly prepared lime milk mixed
with iron ochre is now added and then an aqueous solution of water glass. The
addition of lime is to be such that the liquid after complete purification will still
undergo an alkaline reaction.
The quantitative proportions in which the said agents are applied vary according to .
the condition and nature of the sewage to be purified.
The limits within which the said agents can be used, are for 1000 hectolitres of
sewage as follows.
to 1 metre-quintals of ferric hydrate disintegrated with sulphuric acid of
50 per cent.

page_text: 2 to 6 metre-quintals of fresh caustic lime which is slaked to form lime milk, and
mixed with 5 to 10 per cent of ochre.
5 to 20 Kilogrammes of water glass of 30 degrees, Beaumé, diluted with water.
The precipitate obtained from the sewage by the addition, effected as described, of
the above-named agents is very consistent and of a brownish colour. The same is
separated from the clear liquid by means of a system of soparating pits or basins or by
mechanical filtration.
The liquid thus purified and cleared is conducted through a second system of basins,
in which smoke gases from chimneys or smoke flues are forced through the liquid by
means of a fan, injector, or pump. The smoke gases besides containing from 12 to
16 per cent of carbonic acid also contain carbonic oxide gas, sulphurous acid, and a
series of empyreumatic products. Some of the latter act energetically upon the algae
and bactinaceo or schizomycetes contained in the water and extirpate the same thus
preventing the subsequent deterioration of the water owing to their presence; whilst
the lime existing in a dissolved state in the water is precipitated by the carbonic acid]
in a crystalline form as carbonate of lime carrying with it any remaining impurities.
After the smoke gases have been passed through the liquid, it is advantageous to
restore the alkalinity of the water by a fresh addition of lime milk.
In the last two separating basins through which the liquid passes or in the last only,
one or more upright filters, containing an effective filtering agent such as charcoal,
coke, stones, fragments of stone, gravel, slag, ashes, wood, wool, saw dust, or filter cloth
can be arranged so that a final mechanical purification takes place the water flowing
off perfectly clear and pure.
Although it is most suitable, and the simplest and cheapest method to employ the
gases contained in the smoke for the purification it is obvious that its effective
ingredients can be used alone or in any desired combination.
The described process is very simple and requires a comparatively slight expenditure
it is at the same time very effective, and presents, as compared with other purifying
processes, the extremely important advantage that substances which are injurious to
health are not introduced into the water, so that the latter is prevented from becoming
a source of danger owing to its poisonous nature despite the purification.
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 ;-
First. The primary purification of sewage by the combined application, of ferrie
sulphate, lime, iron ochre, and a solution of water glass, substantially as described and
for the purpose specified.
Second. The secondary purification of the partly purified sewage, by means of
smoke gases or their equivalents passed through the liquid substantially as described
and for the purpose specified.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicants.