to other Foul or Impure Waters.
Year: 1885

page_text: to other Foul or Impure Waters.
I FARNHAM MAXWELL LYTE of Cotford, Oakhill Road, in the County of Surrey,
Analytical Chemist, do hereby declare the nature of the said invention for
"IMPROVEMENTS IN SEWAGE PURIFICATION PROCESSES, APPLICABLE ALSO TO OTHER
FOUL OR IMPURE WATERS," to be as follows:-
In a former application for Letters Patent dated January 21st 1885, No 900,
I specified the sodium aluminate for the purification of sewage and other foul
waters, when mixed with the requisite quantity of an acid, a salt of alumina, or
some other acid salt, as being a cheaper and more ready means of forming the
quantity of aluminium hydroxide necessary for the precipitation of the organic
matter, than the process with aluminium sulphate now in use. I have since found
that several other salts even if neutral in the strict sense of the term, as the
calcium sulphate or chloride, or the salts of magnesium, zinc, in fact any of the
Balts of the heavy metals and numerous others, act like acid salts, in so far as
sodium aluminate is concerned, in setting free the alumina by reason of the superior
affinity of the sodium for their acid, as compared with that of their acid for the
base which they contain. By this means the base of the salt, whether it be lime,
magnesia, zinc oxide or otherwise, is set free also as a hydroxide along with the
alumina, but it does not interfere with its precipitant action, rather helping it than
otherwise. The reaction is exemplified by the following formula, adopting the
nomenclature of Roscoe, vizt :—
Na, Al, 0, + Ca SO, + 4 H₂ O = Na₂ SO, + Al₂ (HO), + Ca (HO),

page_text: to other Foul or Impure Waters.
I FARNHAM MAXWELL LYTE of Cotford, Oakhill Road, Putney, in the County
of Surrey, Analytical Chemist, do hereby declare the nature of the said invention
for "IMPROVEMENTS IN CLARIFYING AND DEODORISING SEWAGE AND OTHER FOUL
AND IMPURE WATERS," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
=
In a former application for Letters Patent dated January 21st 1885, Nº 900,
I specified the use of sodium aluminate or other soluble aluminate for the purifica-
tion of sewage and other foul waters, when mixed with the requisite quantity of
an acid, a salt of alumina, or some other acid salt, as being a cheaper and more
ready means of forming the quantity of aluminium hydroxide necessary for the
precipitation of the organic matter than the process with aluminium sulphate
now in use.
I have since found that several other salts, even if neutral in the strict sense of
the term as for instance the calcium sulphate or chloride, or the salts of magnesium,
zinc, or indeed any of the soluble salts of the earthy or heavy metals and numerous
others act like acid salts in so far as the decomposition of sodium aluminate is
concerned by reason of the superior affinity of the base of the aluminate for their
acid, as compared with that of their acid for the base which they contain. The
reaction is exemplified by the following formula, adopting the nomenclature of
Roscoe and supposing temporary hardness or carbonic acid to be also present in
the water, viz :-
.
Na₂ Al, O + Ca SO. + 00, + 3 H₂O = Na, SO, + A₁₂ (HO), + Ca CO,.
In the example represented by the above formula calcium sulphate is the salt
chosen for the purpose of decomposing the aluminate, and it will be seen that this
salt is one of the impurities which give to water what is usually termed " permanent
hardness." The reaction will take place equally well with any of the other salts
which constitute " permanent hardness," but for the purpose of describing my
Invention, I mention only calcium sulphate. I do not however limit my Invention
to the treatment of water, the hardness of which is due to the presence of this salt.
Water may therefore be freed from this "permanent hardness" by the use of the
sodium or other soluble aluminate. For each degree of permanent hardness about
2-27 grains of raw aluminate of 27.3 per cent of soda and 33-5 per cent of alumina
will be required.
In the above formulæ the calcium is noted as being carbonate, but the fact is
that the calcium oxide probably combines with alumina and precipitates as an
aluminate; but when carbonic acid is present, the calcium (or any other base
which may be present) having an affinity for the acid is gradually separated from
the alumina as carbonate. In such cases then aluminium hydroxide may be
formed and take up organic matter. In both cases the use of the aluminate
produces a good precipitate with rapid subsidence. Temporary hardness due to
so-called bicarbonates can also, if desired, be destroyed by the use of sodium
aluminate alone,

page_text: The above mentioned reactions it should be observed will take place equally well
with any aluminate other than that specified i.e. sodium aluminate. In practice
however, none other than soluble aluminates could be employed. The soluble
aluminates known to science are, besides sodium aluminate, those of potassium,
barium, strontium and lithium, but these not being known in commerce are not at
present available for the purposes of this Invention. I am therefore practically
limited to that of sodium aluminate and I recommend the use of a specially
prepared aluminate of which Mess Steinkopff & Co of 2 East India Avenue,
London, E.C are the sole vendors in this kingdom. I have hitherto often found
it preferable to use the sodium aluminate, not in solution but in fine powder as in
some cases the precipitate formed when a solution is used is apparently so finely
divided as not to settle readily, but on the contrary, passes through ordinary
filtering media.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1st The herein described process of clarifying and deodorising sewage and other
foul or impure waters, which process consists in the addition to the liquid of the
sodium or other soluble aluminate together with a neutral earthy or metallic
salt-such as sulphate or chloride of calcium-in sufficient quantity for its acid to
neutralise all or part of the base contained in the aluminate, substantially as
specified.
2nd The herein described process of clarifying purifying water for domestic and
manufacturing purposes, (producing in the liquid either hydroxide of aluminium
and calcium or other carbonate or an aluminate as a rapidly subsiding precipitate)
by adding sodium or other soluble aluminate to water containing either or both
forms of hardness, substantially as specified.