IMPROVEMENTS IN THE TREATMENT OF TOWN SEWAGE AND IN APPARATUS TO BE EMPLOYED THEREIN
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Richard Nicholls at the Office of the
Commissioners of Patents on the 14th December 1882.
RICHARD NICHOLLS of 2 Purbrook Villa Victoria Road, Hendon in the County
of Middlesex Electrical Cloth Manufacturer." IMPROVEMENTS IN THE TREATMENT
OF TOWN SEWAGE AND IN APPARATUS TO BE EMPLOYED THEREIN
"
My invention has for its object the deodorizing of town sewage-the conversion
of the solid portions thereof into a valuable manure-the extrication from both the
solid and liquid portions thereof of the ammonia and ammonical salts therein
contained converting the same also into a valuable manure-and the return of the
liquid portions in a sweet and healthy condition to any neighbouring watercourse
without contaminating or rendering the same unfit for the ordinary uses of river
water.
The manner of performing my process is as follows:-
The sewage flows direct from the sewer into a large receiving tank or tanks of
any required size or capacity of any suitable material and shape convenient for the
processes to be hereinafter detailed-The shape I prefer is that of a long parallel-
ogram or trough made of cast iron with a cover to the same as herein after
described
Either before the sewage is let into the tank a quantity of burnt earth or burnt
clay and crushed coke is placed in the bottom of the tank with which the sewage
thoroughly mingles as it rushes in-or similar ingredients are sifted into it along
the whole coarse of the tank after the sewage is there. It is then allowed to
settle. The next step is to treat the mass with hydrate of lime--I find that a
proportion of something like one ton to a million of gallons answers the purpose
although the exact proportion is not material, provided the lime does not fall short
of the above.
In some cases and particularly when a very clear effluent is demanded I here add'
some sulphate of alumina in solution and allow sufficient time for it to carry down.
to the bottom any matters with which it may combine in a solid form or any
precipitates to which it may give rise.
As soon as all the solid portions of the mass have fallen to the bottom leaving
the liquid above clear which takes place in the coarse of one to two hours, the,
liquid is drawn off by suitable taps into other tanks placed at hand to receive it.
ご

page_text: :
It is not necessary that these tanks should be or any particular size or shape or
material provided they are suitable for the process I am about to describe. I find
long tanks or troughs similar to the tank above described fitted with covers
capable of being removed answer the purpose.
TREATMENT OF THE LIQUID PORTION
The tanks into which the liquid is run must be so constructed that their
contents can be heated to boiling point. This may be effected by an arrangement
of furnaces and hot flues or by pipes conveying steam and passing through the
liquid or by a steam jacket surrounding the bottom and sides of the tank or by
any other known means. The tanks must also be fitted with air tight covers
capable of being lifted off or moved off on one side and when needed of being made
fast to the top of the tank with air tight joints. Along the top of this cover and
replacing that part of it is a perforated tray running nearly the full length of the
cover and constructed so as to hold soot or charcoal or other suitable material to the
depth of from 18 inches to 2 feet. The perforations of the tray open on the lower
side into the tank and communicate direct through the soot charcoal & with the
open air on their upper side so that all gases or vapors generated in the tank are
at liberty to pass through them, traverse the bed of soot charcoal &c and escape
into the air save so far as they are caught and fixed by the bed of absorbent
material.
The effect of this arrangement is that as the liquid becomes heated in the tank
the vapor steam and ammonical vapours or gases pass up through the perforations
and while the steam escapes the whole of the ammonia is retained by the absorbent
material contained in the tray.
As regards the absorbent material I find that soot moistened with dilute
sulphuric acid (one part of oil of vitroil to nine parts of water answers very well) is
as good a material as any, but many forms of carbon or other similar material
which can be conveniently obtained would do instead-and I have found that
certain descriptions of sawdust previously roasted and moistened with the dilute
acid as above mentioned will answer the purpose. It is best to keep the liquor
boiling for at least five minutes to ensure the complete extrication of the ammonia.
The liquid is then run out onto a bed of crushed coke and allowed to flow away
free from all smell and taint into the nearest water-course. The contents of the
tray containing all the ammonia with which the liquid was charged are then
removed and dealt with as presently described.
TREATMENT OF THE SOLID PORTIONS
The receiving tank'in which the solid portions of the sewage are left when the
liquid is drawn off as above mentioned requires to have an air tight moveable
cover similar to that already described for the tanks in which the liquid was
treated, and a similar tray running along the top of it with a perforated bottom
for the reception of the absorbent material. It requires also arrangements of a
similar nature for heating its contents with the exception that steam pipes passing
through it would not be admissible.
The cover having been fastened down and the perforated tray charged with a
depth of at least eighteen inches of soot or other absorbent material as previously
described but without the need of any acid the tank is then heated and the heat
is continued to at least 400° Fah and may be carried further provided it does not
reach a point at which the solids are burnt. As the process proceeds both in the
tanks containing the liquids, and the tank containing the solids, the vapours and
gases passing through the absorbent material in the tray are constantly tested from
time to time and if any ammonia is discovered escaping through it, additional acid
or soot or both are immediately added the object being to fix and retain the whole
of the ammonia. As the amount of ammonia in any tank at starting cannot be

page_text: with accuracy ascertained it is not possible in the first instance to determine with
accuracy the amount of absorbent material which will be required.
When the heating of the tank is completed and its contents freed from ammonia
which is ascertained by the use of a stick which passes through a hole in the cover
to the bottom of the tank and which is tested for ammonia when withdrawn and
also by the smell thereof-the cover is taken off and the solid material which will
be found in the form of an inodorous brown cake or powder is thrown out with
shovels and mixed with the absorbent material from the trays the whole forming
a manure of great value. Another test of the process being complete is by
testing the vapours or gases which issue from the hole in the cover just
described.
A variation may be made in the treatment of the solid portions of the sewage
by leaving the results of the first charge in the tank after the liquid is drawn off
without heating it, and pouring or sifting into it a layer of burnt earth or burnt
clay and crushed coke as previously described so as to form a bed to receive and
deodorize the next charge and so on for two or more charges until the tank is
nearly full (the number of charges depending of course on the depth of the tank
and the quantity of solid refuse in the sewage) and then putting on the cover and
heating it as before described. In this case the depth of the absorbent material in
the tray or the quantity of dilute acid may have to be increased.
In conclusion I have to state that my process is applicable with considerable
profit to all ordinary sewage with the amount of water ordinarily contained therein
and that in principle it is applicable to sewage containing any amount of water
but that I do not propose to apply it as a profitable process to sewage when
mingled with the waters proceeding from a beavy rainfall.