Improvements in or connected with Filters for the Purification of Sewage and other Foul Liquids by Bacterial Action.
Year: 1898

page_text: Improvements in or connected with Filters for the Purification of
Sewage and other Foul Liquids by Bacterial Action.
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 has for its object to supply an aerobic bacterial filter with the oxygen
necessary for the maintenance of bacterial action, at such a temperature as will
ensure the encouragement of such action in cold weather, the invention being par-
ticularly applicable in connection with filters of the kind for which former Letters
Patent were granted to me dated the 9th day of January 1897 and numbered 654.
The object of the present invention is accomplished by the employment of air
heating and distributing arrangements whereby atmospheric air at the proper
temperature is equably and continually disseminated through the filter bed, the
walls of which if constructed as described in my previous patent aforesaid would
be enclosed in outer walls or otherwise provided with means of preventing the
direct admission of cold air.
According to one arrangement the filter bed is traversed by flues which open
to the outer air under the control of air inlet regulating valves. The flues may rise
towards the interior and they have perforated sides or are otherwise adapted to
permit the air to escape from them into the filter bed. Through these flues are
laid pipes heated by the circulation of hot water from an external heater so that
the air entering the flues becomes warmed and escaping from the flues into the
filter bed a constant current of fresh warm air is maintained.
According to another arrangement one or more air chambers would be provided
transversely beneath the floor of the filter bed and communicating with the outer
air under the control of air inlet regulating valves. From the upper part of each
air chamber flues extend longitudinally through the filter bed, the flues being
perforated and laid at an upward inclination from the air chamber. Within the
chamber a hot water coil or radiator is placed whereby the air is warmed and
caused to rise within the chamber and enter the flues whence it escapes into the
filter bed a constant current of warm air being thus set up and maintained.
Instead of the coil or radiator a slow combustion stove might be used but the
former is preferred as giving a more equable temperature.

page_text: Improvements in or connected with Filters for the Purification of
Sewage and other Foul Liquids by Bacterial Action.
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 has for its object to enable an aerobic bacterial filter to be supplied
with the atmospheric oxygen necessary for the maintenance of bacterial action
at such a temperature as will ensure the maintenance of the vitality of the micro-
organisms in cold weather, the invention being particularly applicable in con-
nection with filters of the kind for which former Letters Patent were granted to
me dated the 9th day of January 1897 and numbered 654.
The object of the present invention is accomplished by the employment of the air
heating and distributing arrangements illustrated in the accompanying drawings
forming part of this specification wherein I have represented two different systems of
supplying warmed air to the filter bed. Figure 1 is a sectional plan of part of
a filter and Figure 2 is a sectional elevation shewing a slightly modified disposition
of the heating flues and pipes. Figure 3 is a sectional plan of part of a filter,
shewing another arrangement for supplying the heated air to the filter, and
Figure 4 is a transverse section of the same on line 4-4 Figure 3.
The preferred mode of ensuring the equable dissemination of warmed air through
the filter bed consists in warming the air within perforated air flues which
traverse the filter bed, by means of hot water circulating through pipes laid in the
flues themselves so that the heat being conveyed by the forced circulation of the
water and imparted therefrom to the air immediately at its point of entry into
the filter bed, the distribution of the heat is more uniform and no special means
are necessary to control the flow of the heated air so as to ensure its uniform
distribution throughout the mass of the filter bed.
Such an arrangement is illustrated in Figures 1 and 2 in which A are the
apertured walls of the filter bed constructed of earthenware pipes set transversely
and enclosed at a distance within outer walls B of solid brickwork the intervening
space C being roofed in so as to form an enclosed area and prevent the direct
access of cold air to the apertured walls in cold weather, as described in the speci-
fication of my former patent aforesaid. I are air flues laid across the floor of
the filter bed and extending through the walls A, across the area C, and opening
at 6 through the outer walls B under the control of flap ventilators or shutters
(not shewn) whereby to permit the inflow, but prevent the outflow, of air
especially to prevent wind blowing against the wall B causing a draught com-
pletely through the flues which would carry away the heated air. The flues
have perforated sides so as to permit the air to enter the filter bed without allow-
ing the water entering the flues and they may be conveniently constructed of
ordinary perforated bricks set on edge to form the sides of the flues of which
the top may be formed of earthenware or other slabs. The flues are preferably
nine inches square internally at the ends but for the greater part of their length the
height of the flue is increased by an additional course of perforated bricks so as to
permit the warmed air to rise in the flue and by the contracted height of the
Hlue at the ends prevent the warmed air escaping except through the perforated
sides of the flues into the filter bed. The parts of the flues which pass through the
walls A may be earthenware pipes d whilst the parts which bridge across the area C
may be brickwork chambers d¹ enclosing the elbows of the hot water pipes and
covered with slabs so as to have no communication with the area C. Throughout

page_text: the air flues D are laid hot water pipes E E¹, forming part of a circulation system
which may be arranged in any suitable manner for the maintenance of the circu-
lation of water heated by any suitable means. In the example shewn in Figure 1
the water is heated by a boiler F arranged in a chamber at one side of the filter
from which flow and return pipes e e¹ lead along the area at one side of the filter
the pipes E E¹ being laid in adjacent flues and connected respectively the one E
with the flow pipe e and the other E with the return pipe the two pipes being
connected at their opposite ends by a coupling pipe E laid in the area at the
other side of the filter, all the pipes E (in alternate flues) being connected with the
common flow pipe e and all the pipes E' with the common return pipe el. In
order to diminish the velocity of flow of the water through the pipes E E¹, and
afford a sufficient heat radiating surface, they are made of larger diameter than
the flow and return mains.
The arrangement above described applies to the case where but a single tier
of air flues is provided. It may however be desirable to provide two tiers of flues
as shewn in Figure 2 in which D are the flues on the floor of the filter bed as
before and D' an upper tier of flues immediately over the lower ones D upon which
they may be supported by brickwork pillars & the floor of the upper flue D' being
formed of stone slabs bridging over the spaces between the pillars. These flues
are constructed like the lower ones and open through the walls A and communicate
with the outer air through openings in the enclosing walls B provided with
non-return flap ventilators or shutters as before. In this case the hot water
pipes E passing through the upper tier of pipes would be connected with the flow
main e and those E¹ passing through the lower flues D with the return main e¹ the
pipes E E being connected by the vertical pipe 12. In other respects the arrange-
ments for the supply and distribution of the heat for warming the air and delivering
the warmed air to the filter bed are similar to those above described.
It is to be understood that I do not limit myself to the transverse arrangement
of the flues as they might be laid longitudinally. According to the arrange-
ment illustrated in Figures 3 and 4 the flues D), having perforated sides as before,
are laid longitudinally of the filter bed and extend from the upper part of a central
air heating chamber H to the end wall of the filter bed where their ends are
closed. The air heating chamber H is constructed transversely below the floor
of the filter bed and the roof of the said chamber H rises above the level of the
floor of the filter bed sufficiently to enable the flues D to open into the upper
part of said chamber. Within the chamber H is placed a slow combustion stove I
or it may be a hot water coil or radiator heated by a boiler located within an
adjacent chamber, whereby the air of the chamber H is warmed and caused to
rise therein and enter the flues 1 whence it escapes into the filter bed, a supply
of fresh air being constantly admitted to the chamber H. In order to ensure the
equable distribution of the warmed air, the perforations in the sides of the flues
would be graduated a few only of the perforations in the bricks nearest the air
heating chamber being left open, the remainder being stopped and the number left
open gradually increasing in proportion to the distance from the said chamber.
It will be obvious that instead of supplying heated air to the flues the latter may be
supplied with external air warmed in the flues themselves by hot water circulation
pipes extending through the flues as first described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. The combination with an aerobic filter for the purification of sewage and
other foul liquids by bacterial action, of the herein described means of supplying
warmed fresh air to the interior of the filter bed such means consisting essentially
of air flues traversing the filter bed and perforated for the emission of the air and
of a system of hot water circulation pipes laid through the flues for warming the
ir therein substantially as specified.

page_text: .
2. The combination with an aerobic filter for the purification of sewage and
other foul liquids by bacterial action, of the herein described means of supplying
warmed fresh air to the interior of the filter bed such means consisting essentially
of air flues traversing the filter bed and perforated for the emission of warmed
air the flues being in communication with the upper part of an air heating
chamber below the filter from which they receive a supply of fresh air warmed by
a radiator or stove in said chamber substantially as specified.
Dated this 6th day of February 1899.
"
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.