AN IMPROVED PROCESS FOR TREATING SEWAGE AND FOR UTILIZING CERTAIN PRODUCTS DERIVED THEREFROM, WHICH IMPROVEMENTS ARE PARTLY APPLICABLE TO OTHER PURPOSES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by William Alexander Lyttle at
the Office of the Commissioners of Patents, with his Petition, on
the 13th July 1874.
I, WILLIAM ALEXANDER LYTTLE, of the Grove, Hammersmith, in
the County of Middlesex, Engineer, do hereby declare the nature of
the said Invention for "AN IMPROVED PROCESS FOR TREATING SEWAGE AND
FOR UTILIZING CERTAIN PRODUCTS DERIVED THEREFROM, WHICH IMPROVEMENTS ARE
PARTLY APPLICABLE TO OTHER PURPOSES," to be as follows:-
One of the objects of this process, and its chief claim to the merit of
public utility, is to create a market for the sedimentary matter of sewage,
commonly known as "sludge," which is now almost everywhere destitute
of value, and is a serious loss to the corporations of towns. The new
use to which I propose to put this sludge is that of an auxiliary to the
materials now used in the smelting of iron.
Owing to the large proportion of carbonaceous matter which the
sludge contains, its use will effect a proportional saving in fuel, whilst
the silicates derived from the wear of the road metal of the streets will

page_text: in which it may be used. For instance, the sludge may be deodorized
by peat charcoal, or by one of those well-known imitations of animal
charcoal, consisting of mixtures of peat with lime or clay, or both
together, such mixture being coked. The carbon thus added will still
further augment the value of the sludge as fuel. The lime, if such is
mixed with the charcoal, will also answer to accelerate the fluxing of
the ore on account of its intimate incorporation with the silica of the
sludge.
"
Sludge can also be used as the means of agglutinating into solid
masses the "duff' or colliery dust of coal, or the dust of peat charcoal
for smelting purposes, with or without an admixture of clay or lime, or
both together. The sludge fuel can be made into lumps and thrown
into the smelting furnace with the ore in the usual way.
Sludge can also be used as an ingredient in the preparation of a
metallurgical concrete containing the entire ingredients of a smelting
furnace charge in any required proportions, namely, crushed iron ore,
quicklime, sand, and powdered fuel; all these materials being well
mixed and worked as a plastic mass with the sludge into suitable
lumps.
The effluent water which passes off when the sludge has been allowed
to separate from sewage I propose to clarify as follows:-I provide a
pug mill with a false bottom consisting of a bed of gravel acting as a
strainer, and I supply peat or any other charcoal to this mill, until, with
the admixture of sewage water, it has been worked into a creamy paste.
No more charcoal is then added, and by means of a float cock the foul
sewage water is allowed to run into the mill at the top as fast as the
clarified water escapes through the gravel at the bottom.
When the filtering charcoal is exhausted it can be incorporated with
the sludge for smelting purposes with or without a previous coking to
extract the ammoniacal salts. This pug mill arrangement I designate
a vortex filter, and the same filter will be of great value as the means of
supplying absolutely pure water to towns.
The value of this arrangement of filter lies in the fact that its action
cannot be impeded by the clogging of its upper stratum with gummy
matter, the slow movement of the pugging arms maintaining a constant

page_text: mixture of the entire mass. This filter will answer with animal charcoal
in all its manufacturing applications as a filtering agent. If all the
charcoal required for the daily use of any town as the means of perfectly
clarifying its sewage water and deodorizing the sludge is first put to
the work of imparting an extra degree of purity to the drinking water
supply of such town, the quantity of charcoal will be so large as
compared with the organic impurities of such water that the drinking
water can thus be rendered absolutely chemically pure without any
material deterioration of the charcoal for its subsequent duty to the
sewage.
The pug mill is provided with a sluice or door at one side of the
bottom, through which the exhausted charcoal can be expelled, and the
pugging arms are arranged upon a vertical shaft with a gearing for
propulsion by any desired power, in the same way as a brickmaker's
pug mill.
Any acid or salt useful in precipitating the ammonia or other
impurities of the sewage water may be also supplied as part of the
charge of the vortex filter when used for sewage, except salts or acids
containing sulphur or phosphorus, these being injurious to iron.
Chloride of calcium, and many other chemicals are well-known as useful
for this purpose.