Improvements in Filtration.
Year: 1892

page_text: Date of Application, 24th Mar., 1892
Complete Specification Left, 15th Dec., 1892-Accepted, 21st Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Filtration.
I SIDNEY RICHARD LOWCOCK of 35 Waterloo Street, Birmingham in the
County of Warwickshire Civil Engineer do hereby declare the nature of this
invention to be as follows:-
In a filter for the purification of polluted fluids the injection of air or oxygen
gas under pressure into the body of the filtering medium so as to produce more
complete aerification of the filtering medium and the fluid filtered, and consequently
more complete purification of the said fluid. The air or gas is forced into the
body of the filtering medium, which is of earth, sand, or other porous material,
under pressure through perforated pipes or channels imbedded in the filtering
medium and so arranged as to diffuse the air or gas evenly through the filtering
medium and bring it into intimate contact with the fluid in process of purification
in the pores of the filtering medium and so produce more complete aerification and
purification of the fluid passing through the filtering medium.
Dated this 19th day of April 1892.
SIDNEY K. LOWCOCK,
COMPLETE SPECIFICATION.
Improvements in Filtration.
I, SIDNEY RICHARD LOWCOCK, of No. 35 Waterloo Street, Birmingham, in
the County of Warwick Civil Engineer, do hereby declare the nature of my
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
My invention has for its object the rapid and effectual removal of organic
matter both animal and vegetable from liquids containing it, such for example as
sewage and sewage polluted water and consists in conducting the filtration of such
liquids in the manner and by means of the apparatus hereinafter described.
The essence of my invention consists in subjecting the liquid to be purified to a
filtering process in which the filtering, material is kept charged with atmospheric
air or oxygen introduced into and forced through the said material under pressure,
the liquid slowly descending through the filtering material and meeting in its
descent the atmospheric air. The liquid in a state of minute division is thus
rapidly and effectually aërated and the organic matter rapidly resolved into
innocuous inorganic compounds whether by direct oxidation or by the action of
bacteria or micro-organisms.
In the accompanying drawing
Figure 1 represents in longitudinal section and Figure 2 in cross section a filter
constructed according to my invention.
A is the top surface of the filter to which the liquid to be purified is evenly
supplied; B is a layer of more or less finely porous material by which the rate
of flow of the liquid through the coarser material below may be regulated;
C and F are layers of filtering material, for example sand or sandy soil;
D and G are layers of fine gravel or stones supporting the finer filtering material;
E is a layer of coarse gravel or stones in which the perforated air pipes J J are
laid. These pipes and the layers E and D distribute the air with approximate
uniformity through the whole material of the filter; H is a similar layer of coarse
gravel or stones in which the drain pipes K K are laid: I is the main air pipe
through which the air or oxygen under pressure is forced by a rotary fan or other
077

page_text: blower or compressor and conveyed to the branch air pipes JJ: L is the main
drain having a free outlet below the level of the bottom of the filter. This pipe
conveys from the filter the purified effluent collected by the pipes K K.
The action of the filter is as follows: The liquid to be purified is supplied to the
surface of the filter at A. Air or oxygen is forced into the body of the filter
through the perforations in the pipes J J embedded in the layer of gravel or
stones E and the said air or oxygen is distributed through the whole material of
the filter. The downward flow of the liquid is retarded in the upper portion of the
filter by the fine material of which the said upper portion is made and by the
pressure of the injected air and the flow of the liquid is accelerated in the lower
portion of the filter by gravity and by the pressure of the injected air. The
uppermost layer or layers of the filtering material are charged with the liquid
which passes slowly downward from them in thin films over and between the coarser
grains of the material forming the lower and principal part of the filter. The
interstices in the lower part of the filter being larger than those in the upper part
the said interstices are not filled with the liquid which runs over the grains or
particles of the filtering material leaving the said interstices so far unoccupied by
liquid as to permit of the free circulation in the filtering material of the introduced
air or oxygen.
By this fine division of the liquid its absorbing surface is enormously increased
and the liquid becomes rapidly charged with the air or oxygen to which it is
exposed.
The pressure at which the air or oxygen is introduced into the filter must be
below that at which the filtering material would be disturbed and blow holes
formed. I have found that a pressure equal to a head of three inches of water in
a filter having a total depth of three feet and in which the air or oxygen is
supplied at a depth of eighteen inches from the surface of the filter answers well in
practice. I do not however limit myself to these proportions as they must be
varied according to the nature of the filtering material available at the locality
where the filtering is conducted.
Although my invention is specially adapted for the purification of liquids from
organic matters by aëration yet I wish it to be understood that liquids treated
according to my invention are also mechanically filtered, that is, are cleared of
suspended solid particles contained in them. The solid suspended particles are
collected on the top of the layer of filtering material and the said top layer must
be renewed from time to time according to the rate at which the solid matter
accumulates on it.
I prefer however to deprive the liquid to be operated upon to a great extent of
suspended matter by previously storing it for a time in a subsiding tank.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that I claim as
my invention of "Improvements in filtration " :-
Constructing and arranging the parts of filters for purifying sewage and other
liquids from organic and suspended matter substantially in the manner hereinbefore
described and illustrated in the accompanying drawing; that is to say, by passing
the liquid through a filter the upper portion of which is made of finely divided
filtering material through which the liquid passes slowly and by which it is freed
from suspended particles; the lower parts of the filter being made of coarser
filtering material over and between the grains of which the liquid descends more
rapidly the interstices in the lower part of the filtering material being supplied
with a current of atmospheric air or oxygen under pressure whereby the liquid is
rapidly aërated and purified from the organic matter contained in it."
Dated the Fourteenth day of December 1892.
SIDNEY RICHARD LOWCOCK.