Improvements in, or connected with, the Purification of Water, Sewage, and other Foul Liquids.
Year: 1897

page_text: PROVISIONAL DIECIFICATION.
Improvements in, or connected with, the Purification of Water,
Sewage, and other Foul Liquids.
I, WALTER MARDON DUCAT, Colonel late Royal Engineers, of 13, Devonshire
Terrace, Hyde Park, London, W., do hereby declare the nature of this invention
to be as follows:
--
My invention relates to the purification of water sewage and other foul liquids
and has for its object to ensure the continuous aeration by natural means (as dis-
tinguished from forced draught) of the filtering medium and consequently of the
liquid passing through it and actually undergoing the process of purification.
The invention consists essentially in the provision of an air inlet channel or
channels opening within the mass of material contained in the filter
ΟΙ nitrification chamber, said channel or channels leading into said
mass either downwards from above, inwards through the sides, or up-
wards through the bottom, of the chamber and being provided at their inlet ends
externally of the chamber with cowls or other contrivances and otherwise so
arranged as to cause a circulation of air to be induced by natural means through
the said channels by which the air is conveyed within and distributed throughout
the mass of filtering medium. The function of these channels is therefore quite
distinct from that of ventilation pipes heretofore used for permitting the escape
of air displaced by the pressure of the liquid when first caused to pass through
the filter.
The method of filtration or purification which it is preferred to adopt is alto-
gether different from that heretofore used, as the filtering medium is not sub-
merged either intermittently or continuously, but is supplied continuously in the
form of spray at a rate commensurate with its flow through the filtering medium
so that the processes of filtration and aeration are simultaneous and continuous.
But the invention is also applicable for the purpose of more effectually aerating
filters worked on the constant or the intermittent system.
The invention also relates to the stratification of the filtering medium whether
the system of aeration he carried out by inlet channels, as above described, or by
apertures in the sides of the filtering chamber, the filtering medium for the treat-
ment of sewage being very coarse at the upper part and gradually finer towards
the lower part, that is to say in the reverse order to that of an ordinary water
filter, the object being to so increase the aeration of the upper part of the filter
(which would otherwise rapidly become clogged with sludge) as to cause the sludge
in the sewage to be broken up by biological action and so disposed of.
Dated this 4th day of March 1897.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.

page_text: Improvements in, or connected with, the Purification of Water,
Sewage, and other Foul Liquids.
I, WALTER MARDON DUCAT, Colonel late Royal Engineers, of 13, Devonshire
Terrace, Hyde Park, London, W., do hereby declare the nature of this 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 relates to the purification of water, sewage, and other foul liquids,
in a nitrification chamber having provision for the continuous aeration of the
purifying medium by natural means as distinguished from forced draught.
Such a nitrification chamber was described in the Specification of a previous
application for Letters Patent dated January 9th 1897 No. 654 and the object of
my present invention is to ensure that the degree of aeration and consequently the
intensity of the bacterial or other micro-organic action (which depends on the
aeration) and on which the purifying action itself depends, shall be roughly pro-
portionate to the quantity of solid impurity present in the sewage at the different
stages of its progress through the nitrification chamber.
This object is accomplished by a novel mode of stratification of the filtering
medium which is very coarse at the upper part and gradually less coarse- towards
the lower part, that is to say the reverse order to that of an ordinary filter, the
object of this order of stratification being to permit of the sludge penetrating into
the interstices of the mass of the filtering medium without choking them, so as to
enable the sludge in the sewage to be there broken down by biological action and
so liquefied and disposed of.
This mode of stratification is employed in combination with air inlet channels
leading into the mass of the filtering material in the nitrification chamber, by which
the air necessary for the supply of oxygen required for the maintenance of bacterial
or micro-organic action is conveyed within and distributed throughout the mass
of the filtering medium, the rate at which the sewage or other liquid to be purified
is supplied to the filter being just so much less than the possible maximum rate of
flow through the filtering medium that the latter shall never be submerged and
there shall never be any head of pressure in the nitrification chamber.
This system of stratification and aeration of the filtering medium is illustrated
in the accompanying drawings forming part of this Specification wherein Figure 1
is a half plan, half horizontal section of a filter, the section being taken on two
different planes and Figure 2 is a vertical section of the filter.
The walls A. are apertured or constructed of open work preferably of superposed
rows of earthenware pipes a of about four inches diameter laid in cement, the
pipes extending transversely through the walls at a slight downward inclination
from the exterior to the interior. FF1 F2 F3 are the strata of progressively decreas-
ing coarseness from top to bottom of the filter bed composed preferably of pebbles
cr of clean washed gravel, pumice stone, stone chips, or equivalent material not
liable to become disintegrated by the action of air and water. For purifying
sewage the filter should be (say) about eight feet in height in which case the upper-
most stratum F should be about. two feet thick and of a grade corresponding to
about one inch diameter, the intermediate strata F1 F2 being each about one foot
thick and of a grade respectively of about half an inch and a quarter of an inch
diameter, the lowermost stratum F3 being of a grade corresponding to about
one-eighth of an inch diameter and of a thickness of about two feet six inches or
three feet, the thicknesses of the various strata and- the total height of the filter

page_text: depending however on the impurity of the sewage and the degree of purification
required:
* P
.
'
The less coarse of these strata are themselves divided and are separated from
superjacent strata of filtering material by layers of very coarse pebbles e in which
may be laid open jointed pipes a¹ forming continuations of certain of the rows of
air inlet pipes a, these pipes a¹ and coarse strata e facilitating the equable dis-
tribution of the air through the interior of the mass. At the bottom of the filter
there is a drainage layer of coarse pebbles in which there may be laid open jointed
pipes B leading to outlets in the walls 'A for the discharge of the effluent into a
gutter b. The distribution of the sewage or other liquid should be as uniform as
possible over the area of the. filter and may be effected by allowing it to overflow
troughs supplied through spouts e from a main trough E the troughs D being
adjusted by screws d or otherwise so that the overflow shall be as nearly as possible
uniform throughout their length.
H are removable screens to shield the filter from cold winds and in very cold
weather the space between the screens and the filter may be wholly enclosed and
the air be warmed before being supplied thereto in order to prevent the diminution
of bacterial or micro-organic action by the admission of excessively cold air to the
nitrification chamber..
The essential feature of the invention is that the uppermost and coarsest stratum
be composed of pieces of such dimensions as to leave interstitial spaces sufficiently
large to enable the sludge or solid matter of the sewage to penetrate the mass of
the upper stratum and to be there continuously broken down liquefied and dis-
posed of by resolution into its constituent elements by the benevolent bacterial or
other micro-organic action without liability of the filter ever becoming choked by
accumulation of solid matter, however long it may continue in action without
intermission. As the interstitial spaces are roughly proportional to the degree of
coarseness of the material it follows that by graduating the various strata of pro-
gressively diminishing coarseness in the downward direction the interstitial spaces
will be correspondingly graduated and will be in such relation to the gradually
diminishing amount of solid matter present in the liquid passing through them
that by the provision of the above described means for the admission of air into
the mass of the stratified material a degree of aeration will be ensured at all parts
of the filter adequate to maintain the supply of oxygen necessary for the mainten-
ance of bacterial or other micro-organic action proportionate in vigour to the
amount of impure matter present at each part.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. A continuously acting filter for purifying sewage and other foul waters,
consisting of a filter bed composed of superposed strata of progressively decreasing
coarseness in the downward direction substantially as specified, in combination
with means for the continuous admission of air into the midst of the filter.
2. A continuously acting filter for purifying sewage and other foul waters, con-
sisting of a filter bed composed of superposed strata of progressively decreasing
coarseness in the downward direction contained within walls of tubular or open
work structure for the continuous admission of air to the filter bed substantially
as specified.
3. A continuously acting filter for purifying sewage and other foul waters, con-
sisting of a filter bed composed of superposed strata of progressively decreasing
coarseness in the downward direction contained within walls of tubular or open-
work structure, the strata of the filter bed being separated and divided by coarse
layers of material for the distribution throughout the midst of the filter bed of air
admitted at the lateral apertures as specified.
4. A continuously acting filter for purifying sewage and other foul waters, con-
sisting of a filter bed composed of superposed strata of progressively decreasing

page_text: coarseness in the downward direction contained within walls of tubular or open-
work structure, the strata of the filter bed being separated and divided by coarse
layers of material having open jointed pipes laid therein for the admission and dis-
tribution throughout the midst of the filter bed of air admitted at the lateral
apertures as specified.
Dated this on day of December
1001.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.