Improved Precipitating and Filtering Tanks.
Year: 1895

page_text: Improved Precipitating and Filtering Tanks.
THOMAS BRIGHT WILSON 37 Arcade Chambers St. Marys Gate Manchester
Civil Engineer do hereby declare the nature of this invention to be as follows:-
This improvement is mainly for application to sewage tanks and large filters but
it can also be applied to tanks where the precipitate is of value as in color making
or gold precipitation.
In the ordinary tank in use for the precipitation of solid suspended matter in
order to increase the area of precipitation and to diminish the distance that the
precipitate falls and also to provide a large filtering surface which may be con-
tinuously used while the process is going on as well as for the continuous removal
of sludge ;-I lay on the bottom of the tank a series of pipes preferably of triangular
section outside with truncated corners having their edges in contact and their
ends projecting through the walls of the sewage tank into a discharging pipe for
the effluent filtered or I connect the ends of these pipes inside the tank with pipes
conveying the effluent through the tank wall into the outfall provided with valves
in the usual manner.
These triangular pipes form a series of V channels on the bottom of the
precipitating tank & I connect these V channels through the outside walls into a pipe
for the removal of the sludge either by gravitation or pumping, or I connect these
channels with a main channel to the usual sludge outlet of the tanks.
On these triangular pipes I abut the ends of a number of smaller triangular
porous pipes discharging into them at an angle of 45° or thereabouts at the lower
ends and extending above the water level of the sewage tank at their upper cods.
These pipes touch at their longitudinal edges forming inclined V channels for the
removal of the sludge.
I fill the tank with these inclined porous pipes tier on tier forming a cellular
structure like a honey comb with triangular in place of hexagonal cells.
Thus the outside triangles formed by the porous pipes contain the precipitating
sewage while the interior of the pipes is available for the percolated effluent
and for its aeration also if the effluent be allowed to run off as it filters through
the pipes.
The outside tiers of pipes I make of double height in order to complete the
structure.
I leave passages for the sewage or other liquid to find its way amongst the pipes
and at the lower ends of the inclined porous pipes above the V channels at the
bottom of the tank I leave openings for the sludge to drop through.
I find some advantage in laying the porous inclined pipes with the vertices
of the triangle downwards keeping two sides of the sludge channel free from
deposit but the sludge does not flow away so well as in the V channel.
I prefer the pipes to be of triangular section as giving the greatest filtering
surface to area of pipe, but they may be of square or other sections.
I form the porous pipes of clay mixed with a large proportion of organic matter such
as sawdust, peat dust, breeze &c. and mixed with about 25% of magnetic oxide of
iron, magnetic carbide of iron or any iron ore which will be reduced in burning
to the magnetic state, or the pipes may be made of clay mixed with sewage sludge
(precipitated by an iron salt) & burnt as described in a former Patent of mine,
No. 17275-1891 October 10th. I also may form the pipes of cement made

page_text: porous by admixture with sand & coke dust and with about 25% of magnetic iron
oxide as above.
Dated this 18th day of May 1895.
Improved Precipitating and Filtering Tanks.
I THOMAS BRIGHT WILSON of 37 Arcade Chambers, St. Marys Gate Manchester
Civil 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 improvement is mainly for application to sewage tanks and large filters but
it can be applied to tanks where the precipitant is of value as in color making, gold
precipitation and in other industrial processes.
In the ordinary tank in use for the precipitation of solid suspended matter in
order to increase the area of precipitation and to diminish the distance that the
precipitate falls and also to provide a large filtering surface that may be continuously
used while the process is going on, as well as for the continuous removal of
precipitated matter hereinafter called sludge.
I lay on the bottom of the tank a series of earthenware glazed or concrete pipes
triangular with their edges in contact and their ends projecting through the walls
of the tank into a discharging pipe or channel for the filtered effluent or I connect,
the ends of these pipes inside the sewage tank with pipes or conduits conveying
the filtered effluent through the tank wall provided with suitable valves in the
usual manner.
These triangular pipes form a series of V shaped channels in the bottom of the
precipitating tank and I connect these V channels through the outside walls into
a pipe or culvert for the removal of the sludge either by gravitation or by pumping
or I connect these V channels with larger main channels to the sludge outlet from
the tank.
On these triangular basal pipes I abut the ends of a number of smaller porous or
perforated pipes discharging into them at an angle of 45° to the horizon or
thereabouts through orifices in the sides of the pipes and extending above the
water level of the sewage tank at their upper ends which are open to the air; these
inclined pipes forming by their exteriors V shaped inclined channels for the removal
of the sludge.
I fill the tank with these inclined porous pipes tier on tier forming a cellular
structure like a honeycomb with triangular in place of hexagonal cells.
Thus, the outside triangular tubes formed by the porous pipes contain the
precipitating liquid while the interior of the pipes is available for the percolated
effluent and for its aeration also if the effluent be allowed to run off after filtering
through the pipes at a sufficient rate to leave the lower conduit partly full of
water.
The outside tiers of pipes I make of double height in order to complete the
structure.
I leave passages for the sewage or precipitating liquid to flow amongst the
pipes and at the lower ends of the inclined porous pipes above the V channels at the
bottom of the tank I leave openings for the sludge to drop through.
I find some advantage in laying the porous inclined pipes with the vertices of
the triangles downwards keeping two sides of the pipes free from deposit but the
sludge cannot be flushed away as thoroughly as in the V channels.
I form the porous pipes of about 60% of clay mixed with about 15 per cent. of

page_text: organic matter such as sawdust, peat dust, chaff or coke breeze and about
25 à per cent. of magnetic oxide of iron, magnetic carbide of iron or any iron ore which
may be reduced to the magnetic state by burning or they may be formed of clay
mixed with sludge (precipitated by an iron salt) and burnt as described in my
Patent No. 17275 of 1891.
The pipes are burnt in the usual manner in a kiln.
I also may form the pipes of cement 50% made porous by admixture of sand or
coke breeze about 25% and with about 25% of magnetic oxide of iron as
described above in this case the cellular structure of pipes may be formed in situ
by using suitable cores to form the internal and external cellular tubes; an
economical mode of construction in some cases.
In cases where the filtration of the liquid is not required to be perfect I find it
sufficient to perforate the pipes with small holes in the hanging side as shown in
Fig. 12 on the drawing.
In using this improved precipitation tank I prefer to make it the end tank of a
series so that only the finer precipitating liquid may enter.
The filtering tank is worked either continuously or intermittently, preferably the
former, the sludge valves being regulated open so that separation of sludge and
filtered effluent may go on continuously.
Occasionally it will be desirable to draw off the tank by means of the sludge
valve and to allow the filtered water to reverse its direction through the pores or
perforations of the pipes to clear them.
Fig. 1 on the drawing shews a half plan of an existing precipitation tank with
the invention applied.
This tank is the end one of a series of six worked continuously; the arrows shew
direction of flow.
Figs. 2 & 3 are longitudinal & cross sections.
The bottom of tank is shown at A, sludge channels at B₁ B, & B, and sludge
outlet valve at B.
The main conduit for filtered effluent is shown at C with outlet into rising
tank D and cascade E and through pipe E to sewage outfall.
C also communicates with sludge outlet through valve G.
The parallel basal pipes are shown at H. their interiors communicate through
pipes P, P shewn on Fig. 4 with main conduit C, and their exterior channels with
sludge channels B. B, B, through V spaces & slots J J J.
The inclined pipes are shown at K and honeycomb network in plan formed by
their ends.
Fig. 3 is a section shewing sludge channels connected with a conduit outside
tank by pipes controlled by cocks-in this arrangement the sludge channels can be
put in direct communication with sludge pumps & filter presses.
Fig. 4 shews an enlarged section through filtering pipes K and basal pipes H at
end of conduit C; L, L, L. are stays to prevent pipes moving.
Fig. 5 shows part of Fig. 3 enlarged, the upper sides of pipes K, channels M, M
for passage of liquid and slots N, N for sludge to drop to V channels O, O.
Fig. 6 is a cross section through filtering pipes K showing method of supporting
outside tier by larger pipes.
Figs. 7 & 8 are cross sections of other modes of building up triangular pipes.
Figs. 9 & 10 & 11 are cross sections of other forms of filtering pipes that I
may use.
Fig. 12 is a longitudinal section & plan of a perforated filtering pipe where more
rapid but less perfect filtration is required.
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 1
claim is
1. The general arrangement of a filtering tank with numerous subsidence cells
and channels for removal of deposit, formed by a combination of inclined pipes.

page_text: 2. The use of porous or perforated pipes of a triangular section for filtering.
3. The method of making porous pipes of earthenware or cement with a purifying
medium as described.
Dated this 18th day of February 1896.
THOMAS BRIGHT WILSON.