Improvements in or relating to the Purification of Sewage and Apparatus therefor.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to the Purification of Sewage and
Apparatus therefor.
I, WILLIAM DUNDAS SCOTT-MONCRIEFF, of 14, Victoria Street, Westminster,
Engineer, do hereby declare the nature of this invention to be as follows:
--
This invention has relation to certain improvements in or relating to the
purification of sewage and has for its special object the provision of highly aerobic
conditions in downward filtration. To this end I arrange the filtering materials,
whatever they may be in separate trays or layers one placed above the other with a
clear air space between each, so that the descending sewage drips from one to the
other. As many trays or layers with clear air spaces between may be placed one over
the other as may be found necessary to give any required standard of purification.
Dated this Oth day of August 1897
W. D. SCOTT-MONCRIEFF.
COMPLETE SPECIFICATION.
Improvements in or relating to the Purification of Sewage and
Apparatus therefor.
I, WILLIAM DUNDAS SCOTT-MONCRIEFF, of 14, Victoria Street, Westminster,
Engineer, 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 :-
This invention has reference to certain improvements in or relating to the
purification of sewage bacterially, and has for its special object the provision of highly
aerobic conditions in downward filtration in an improved and novel manner and it
deals preferably with the effluent obtained from cultivation tanks and anaerobic
chambers as set forth in my Specifications Nos. 14181 of 1891, 17006 of 1892 and
13400 of 1897 or with organically contaminated liquids in which the organic matter
has already been broken up into simpler compounds more especially into nitrogen in
the state of free ammonia.

page_text: With the object of obtaining the maximum amount of purification from the work
of liquefying and nitrifying organisms, I distribute the effluent (preferably as afore-
said partially purified or broken up) over the uppermost surface of a series of super-
imposed filters with clear air spaces between them, these filters forming a series of
zones, colonies or survivals of the fittest organisms; and one of the special features of
my present invention is that these superimposed layers or trays with clear air spaces
between should not be arranged in haphazard numbers or be of haphazard depths but
seeing that the improved arrangement affords a new and important means of method
for obtaining exact information I prefer first to obtain the required information by
experiment at the several stages of purification and I then arrange the depth of the
filtering material in each layer or tray so that the maximum amount of aeration is
obtained from it and I arrange the number of superimposed trays so as to obtain any
particular standard of purification which may be necessary or desirable in each or any
case.
In order to make this explanation clear I will give an example from actual working
to show how the foregoing arrangement provides a novel method for obtaining
accurate information as to what occurs in the various stages or layers of the bacterial
filters. The working was carried out at Ashstead, Surrey, with 9 filters, each being
7 inches deep, and there were air spaces of two inches in depth between them. The
effluent was analyzed before entering the first tray and also on leaving each of the
9 trays.
The following table gives the results: —

page_text: From the above series of analysis the changes that occur can be expressed graphic-
ally as in the diagram shown in Figure 1 of the annexed drawings and from the
various lines accurate information can be obtained as to the proper working of the
apparatus in all its parts, the horizontal lines of figures represent the various trays
or stages and the samples taken from them; the vertical lines of figures represent the
number of parts per 100,000 of the various substances indicated.
In order to insure the best results I not only arrange the depth of the materials of
each layer or tray in relation to the maximum amount of aeration (in a practical sense)
to be obtained from it, but I also use preferably a porous material such as coke and I
do this so as to take full advantage of its porosity for the purposes of aeration by
allowing it to be filled and emptied somewhat like a sponge and this I do by dis-
charging the preferably broken up or partially purified sewage intermittently, the
discharge being so arranged that the liquid from a previous discharge may have had
time to drip away, leaving a highly aerated condition of the filtering material for the
next and so on. In order to provide for the even distribution of the preferably
partially broken up sewage I discharge it into double or single tippers or tilters
working on independent axes and these may discharge into subsidiary double or
single tippers or tilters of smaller dimensions preferably working at right angles to
the larger primary tilters or these large tilters may discharge their contents over the
surfaces of perforated plates so arranged that the (preferably partially broken up)
sewage may drip through them as equally as possible over every part of the upper
surface of the uppermost tray or layer. Beneath the lowest tray or layer I provide
for the floor which may be conveniently made of concrete rendered with cement being
dished into one or more hollows each and all of these hollows or channels being
provided with a fall or inclination towards any required point of discharge.
Figure 2 of the accompanying drawings is a side elevation partly sectional and
Figure 3 a plan illustrating an arrangement of apparatus suitable for carrying out
my invention by means of a number of double tilters or tippers which receive the
sewage from a trough and discharge it intermittently over the upper surface of the
uppermost of a number of superimposed filters arranged as trays.
Figure 4 is a plan and Figure 5 a fractional side elevation partly sectional and on
a larger scale than Figure 4 illustrating an arrangement of apparatus suitable for
carrying out my invention by means of double tilters or tippers which receive the
sewage from a trough and discharge it intermittently over the upper surface of per-
forated plates which distribute it over the upper surface of a number of superimposed
filters arranged as trays.
Referring first to Figures 2 and 3, a is a trough which receives the sewage from
any source such for example as cultivation tanks and anaerobic chambers as described
in my Specification No. 13400 of 1897. This trough has two sets of outlet nozzles bb'
through which the sewage flows from the trough respectively into two series of double
tilters or tippers c c¹; if only one series of tilters be employed then only one set of
outlet nozzles will be required in the trough a. The tilters are carried on
horizontal axes d on which they can turn within certain limits and are so mounted
that when one half or side of a tilter is filled with sewage to a given extent from one
of the nozzles b it becomes. overbalanced, the tilter then turns on its axis, and thereby
empties out its contents, the turning movement having the effect of bringing the
other half or side of the tilter below the nozzle b; this half next becomes over-
balanced, the tilter then turns on its axis in the reverse direction and empties out its
contents, this action going on intermittently. The sewage emptied out of the tilters c
is discharged over the upper surface of the uppermost of a number of superimposed
filters arranged as trays ee with clear air spaces between. The number and depth
of these trays and the distance between them should be determined according to the
character of the sewage dealt with and the standard of purity desired. I have shown
six trays and they may be say 8 inches deep with clear air spaces of say 3 inches
between them. They contain a layer of filtering material preferably porous such as
coke and are perforated at bottom so that the sewage may pass out of them in a more
or less divided state and drip from one filter to another. The uppermost filter is

page_text: preferably provided with convex distributors ff below the tilters c c for the purpose
of distributing the sewage more uniformly over the filter. From the lowermost filter
or tray e the effluent falls upon the floor g which is formed with one or more channels
having a suitable fall or inclination to any required point of discharge. It is obvious
that the tilters c may be single instead of double in which case they will be so
mounted as to return to their normal position every time they have been overbalanced
and tilted by the weight of their sewage contents, and have discharged these
contents.
Referring next to Figures 4 and 5, there is in this arrangement a perforated
plate h over the uppermost tray or filter; this plate is preferably divided into
channels by sides or upstands i and it receives the sewage emptied out from the
corresponding tilter or tilters c at every intermittent discharge of same; the sewage
thus discharged upon the plate h spreads over its surface and then passes through the
perforations which distribute it over the surface of the uppermost filter_e. I have
shown in Figure 4 eight sets of filters. The sewage arrives by the main l, passes to
right and left by the branches and these branches again divide into sub-branches m
which discharge into the tippers c c.
It is obvious from the foregoing description and drawings that no hard and fast
line can be laid down either as regards the depth or the numbers of the trays or zones,
but that the dimensions of trays and air spaces and also the number of the trays
must be determined according to the particular character of the sewage to be dealt
with, the invention affording every means for obtaining accurate information by
experiment upon any scale so as to yield the data necessary for obtaining any'
required or necessary standard of purification.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. In the bacterial purification of sewage the use of superimposed trays or layers of
filtering material arranged substantially in the manner herein before described for the
purpose set forth.
2. In the bacterial purification of sewage the use of a porous material such as coke
in superimposed filters arranged as trays with provision for taking advantage of its
porosity for aerating purposes by discharging (preferably partially broken up) sewage
over the upper surface of the uppermost tray intermittently, substantially as herein-
before described.
3. In the bacterial purification of sewage, the intermittent discharge of (preferably
partially broken up) sewage over and through superimposed filters arranged as trays
by means of single or double tilters or tippers substantially as hereinbefore
described.
4. In the bacterial purification of sewage, the intermittent discharge of (preferably
partially broken up) sewage over and through superimposed filters arranged as trays
by means of single or double tilters or tippers emptying their contents over the upper
surfaces of perforated distributing plates, substantially as described.
5. The improved apparatus constructed substantially as herein before described and
represented in Figures 2 and 3 for use in the bacterial purification of sewage.
6. The improved apparatus constructed substantially as herein before described and
represented in Figures 4 and 5 for use in the bacterial purification of sewage.
D
041
1000