AN IMPROVED METHOD OF PURIFYING SEWAGE
Year: 1880

page_text: LETTERS PATENT to Peter Spence, of Manchester, in the County of Lancaster,
Manufacturing Chemist, for an Invention of "AN IMPROVED METHOD OF
PURIFYING SEWAGE."
PROVISIONAL SPECIFICATION left by the said Peter Spence at the Office
of the Commissioners of Patents on the 1st June 1880.
PETER SPENCE, of Manchester, in the County of Lancaster; Manufacturing
Chemist. "AN IMPROVED METHOD OF PURIFYING SEWAGE."
This Invention relates to an improved mode of purifying the effluent waters
derived from sewage after it has been subjected to the ordinary lime process. It
is found that the lime process deposits the greater part of the feculent matter
contained in the sewage, but that the effluent waters are opalescent in color, and
will smell very offensively if kept for any length of time.
In order to remedy these objections I take the sewage or effluent water as it
comes from the tanks where lime has been used for its clarification, and run the
said effluent water into other tanks along with a solution of sulphate, or other salt
of alumina, or alumina and iron.
This will cause the alumina and iron and all the dissolved feculent matters
contained in the effluent to be precipitated; and the effluent thus treated becomes
quite transparent, colourless, and free from odour, and may be allowed to flow
away in any convenient manner, and without risk of contaminating the streams
into which it may be directed.
The
The precipitate of aluminous and iron salt produced by the above process I then
pump into suitable vessels, and add to it a solution of sulphuric or other acid,
preferably applying at the same time or immediately after a slight degree of heat
to the mixture by means of a steam jet or coil, or in any convenient manner.
acid solution will cause all the alumina and iron, if any be present, to be dissolved,
and the resulting solution of the recovered alumina and iron I add to the effluent
waters of the lime process, and utilize them over again, thus effecting in an
economical manner the perfect purification of the effluent waters of sewage.
The application of heat to the mixture as above explained is calculated to hasten
and render more complete the dissolving of the alumina and iron.
I may remark that in my process I prefer to employ a minimum quantity of
lime for the first stage of clarifying the sewage waters.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Spence in the Great Seal Patent Office on the 1st
December 1880.
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist. "AN IMPROVED METHOD OF PURIFYING SEWAGE."
My Invention of an improved method of purifying sewage relates to the
purification of the effluent waters derived from sewage, after it has been partially
purified or clarified by the use of slaked lime or cream of lime, under what is
known as the ordinary lime process. In treating by my improved method the
effluent waters resulting from the lime process, I find that I am enabled to achieve
the best results by using a less quantity of lime than is now used in that process,
and in fact only so much as will precipitate the greater part of the sludge or solid
matter contained in the sewage. Thus an incidental economy in lime is effected.
It is found that the lime treatment, although it deposits the greater part of the
feculent matter contained in the sewage, yet it always leaves the greater part of
the albumen and coloring matter in solution, so that what is called the effluent
from that process is still of a putrescent character, and retains much of the
opalescence, color, and offensive smell of the sewage.
In order to remedy these objections I take the sewage or effluent water as it
comes from the tanks where lime has been used for its purification, and run the
said effluent into a special tank, in which tank I add to it regularly as it flows in a
solution of sulphate or chloride of aluminum or alumina and iron. I have found
that sulphate of alumina with a little iron oxide in solution is the cheapest and
most efficient salt for my purpose, and practically I employ what is well known as
"aluminoferric cake." This solution of alumina and iron I use according to the
character of the sewage effluent under treatment in the proportion of from half ('/)
to one (1) ton of the "aluminoferric cake to one million gallons of the effluent.
This aluminous solution immediately causes the said effluent to assume a milky
appearance, and a flocculent precipitate soon forms and falls to the bottom of the
tank. The effluent then becomes clear, colorless, and free from smell, and may be
run into any river or brook, or used for any manufacturing purposes, but it is of
course not fitted for drinking.
"
The flocculent precipitate above mentioned is then withdrawn from the settling
tank by continuously pumping the same out of the settling tank, or in any other
convenient manner, and it is conveyed into another special cistern or tank where
it is treated with sulphuric or other acid, for the purpose to be presently
explained. This flocculent precipitate contains all the alumina and iron oxide
that were previously in solution, but which are now in a solid form, the acid
having been carried away by the lime contained in the effluent; I now add to the
magma or precipitate pumped up from the settling tanks a quantity of sulphuric
or other acid, equal to that which the aluminous solution originally contained,
and after some stirring this acid dissolves all the alumina and iron oxide con-
tained in the precipitate, and forms again a solution fitted for being added to a
fresh supply of the lime effluent as before, which it will purify by precipitation.
It may be useful to alightly heat the magma and acid by blowing steam into it,
or otherwise, and this heating, which must not be lighter than one hundred and
twenty degrees Fahrenheit, will facilitate the dissolving of the alumina.
I find however that after substantially all the alumina and oxide of iron have
been dissolved out of the solid material, pumped out of the settling tank, a heavy
black flaky matter is left, and this deposit I find to be chiefly albumen, and to be
rich in potential ammonia, or the constituents thereof, and that on being merely
dried it will form a valuable manure. The operations above indicated merely

page_text: require tanks similar to those in use at the present time for the purification of
sewage by the lime process, and a reservoir into which to pump the precipitated
alumina, or alumina and iron, which may again be made soluble by the addition of
acid, as above explained.
It will thus be seen that the alumina or alumina and iron oxide may be used
over and over again, and this at the small cost of replacing the acid which is
required for rendering these bases soluble.
The salts of alumina and iron which are the most efficient if not the only real
purifiers of sewage, are in their ordinary form too expensive for general use in
purifying sewage, but by reducing the expense attending their use, as is effected by
my improvements, to the mere cost of the acid required for dissolving the said
oxides of aluminum and iron, the whole cost of the aluminous salts will be reduced
to something like one third of their commercial price. Either sulphuric acid in its
cheapest forin (say, as chamber acid), or hydrochloric acid will be suitable for the
purpose above described.
My improved method therefore enables me to use the most efficient purifier of
sewage in so economical a form as to make it generally available.
I would remark that although theoretically no waste of the alumina and oxide
of iron would occur, yet practically there would be some loss which would have to
be made good. The iron oxide is not essential to the process, but acts beneficially
like the alumina. A solution of alumina alone would be equally efficient, but is
more expensive.
Having now described the nature of my Invention of "An Improved Method of
Purifying Sewage," and explained the manner of carrying the same into effect,
I wish it to be understood that uuder the above in part recited Letters Patent
I claim, the process above described, whereby the effluent waters of sewage (after
treatment with lime) may be purified in an efficient and economical manner.
In witness whereof, I, the said Peter Spence, have hereunto set my hand
and seal, the Thirtieth day of November, in the year of our Lord One
thousand eight hundred and eighty.