Note: Descriptions are shown in the official language in which they were submitted.
WO 2023/099768
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1
STORM WATER FILTRATION SYSTEM
Field of the invention
5 The invention relates to a storm water filtration system comprising a
filtering well
comprising a filter comprising man-made vitreous fibres (MMVF), a storm water
drain pit and a storm water collection system, particularly wherein the storm
water collection system is an infiltration system.
10 Background of the invention
Storm water (e.g. rain, snow, sleet, hail and water run-off from residential
and
commercial areas) is collected and transported by storm water drain systems.
Typically, the storm water is channelled into the storm water system via storm
15 water drain pits i.e. storm water drains in the ground, also called
storm water
gullies, wells, catch basins or storm water inlets. Storm water drain systems
typically have a number of storm water drain pits, which lead to a network of
underground drain pipes. The storm water is collected by the storm water drain
pits, filtered to remove particulates or debris and then transported to a
desired
20 location.
In times of high precipitation, storm water drainage systems may become
overwhelmed leading to flooding and waterlogging of the ground. In order to
combat this, storm water collection areas, such as water infiltration systems,
are
25 installed. These are designed to store large volumes of excess water.
The water
can subsequently be transported to water collection points and/or allowed to
dissipate into the surrounding ground once it is dry enough and/or used at a
later
stage (for example, to water plants). In this way, storm water collection
systems
can prevent flooding by storing storm water until such a time as it is
convenient
30 to use or dispose of the water.
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For example, WO 2013/072082 Al discloses a water drain reservoir comprising
a coherent man-made vitreous fibres (MMVF) substrate and a conduit having
two open ends.
5 Typically the process of installing storm water drainage and storm water
collection systems into the ground is very disruptive. It can result in entire
streets
being excavated which is time-consuming and disruptive to the residents of the
area. Often municipalities wait until there are multiple reasons to excavate a
street (for example to address other piping or cables underground) before
10 installing water infiltration systems. It would therefore be desirable
to provide a
water drainage and storm water collection system that can be used to prevent
localised flooding, and installed with minimal disruption to the surrounding
area.
Furthermore, it is desirable to collect the particulates, pollutants and
debris at the
15 initial point of entry into the storm water drain system i.e. in the
storm water drain
pit. This is because it is necessary for the particulates, pollutants and
debris,
which build up, to be removed periodically from the drain system in order to
prevent blockage of the drainage and filtering system. Typically, in order for
the
collection of particulates, pollutants and debris to be removed, it is
necessary for
20 an individual (e.g. a maintenance worker) to first remove the filter.
This can be
time-consuming as the storm water drain pit must be, in part, dismantled and
then rebuilt. US 2009/0277820 Al discloses a filtering device for storm water
run-off. It contains a removable frame and a filtering component, which may be
made from fiberglass.
Alternatively, the filter may remain in the storm water drain pit while
cleaning
occurs. For example, W02021/028526 Al discloses a storm water drain pit with
a cylindrical filter. The storm water drain pit cleaning tube can be inserted
inside
the hollow centre of the filter. However, as the cleaning process is very
30 aggressive, this can sometimes lead to the filter being damaged.
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It would therefore be desirable to provide a water drainage system and storm
water collection system in which the storm water drain pits can be regularly
cleaned without removing or damaging the filter.
5 NL1010476
relates to a gully or drain pit for taking care of rapid discharge of
rainwater to a sewerage system. The gully consists generally of a vortex
chamber having a lid provided with openings through which rain water flows
into
the vortex chamber. The vortex chamber is provided with an outlet (swirling
discharge) connected to the sewer. A filter element (sieve) is positioned in,
and
10 over the
entire height of, the vortex chamber. The filter element is preferably
made of plastic. This system is disadvantageous because it can only capture
very coarse particles: small particles can pass through the filter
unobstructed.
EP3674493 discloses a gully having a sewer outlet configured to couple the
15 gulley to
a sewer system. The gully further comprises at least one infiltration
outlet being configured to transfer liquid in the gully to the ground around
the
gulley. A filter element may be positioned in the gully infiltration outlets
and is
made from concrete. This filter is cleaned by using a pressure washer and/or a
vacuum cleaner. As discussed above, this aggressive form of cleaning can
result
20 in damage
to filters and might push the debris further into the pores of the filter,
such that the functionality of the filter does not fully recover to its
original
capacity.
DE10348520 relates to a filter system for water loaded with metal ions, the
filter
25 system
having an inlet, an inlet chamber, a coarse filter (i.e. leaf catcher), a raw
water chamber, a filter chamber containing a filter substrate, a pure water
chamber and a rain water outlet. The filter substrate preferably comprises
zeolite. A buffer can be positioned in connection with the filter system ¨ in
the
event of heavy rain, water can be stored in the buffer before being filtered
in the
30 filter
chamber. The buffer is covered with water-impermeable covering to
prevent this stored water entering the ground.
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WO 2021/130106 Al discloses storm water management system comprising a
first conduit, a storage device, a first well and a valve, wherein the storage
device comprises a coherent man-made vitreous fibre module (MMVF module),
wherein the MMVF module comprises an upper passage and a lower passage,
5 wherein
the upper passage is in fluid communication with the first conduit, and
wherein the lower passage is connected to the first well by the valve. The
disadvantage with this system is that it can only capture very coarse
particles:
small particles can pass into the storage device unobstructed.
10 It would
be desirable to produce a storm water drainage, filtration and storage
system in which the filter does not need to be removed or will not be damaged
when the storm water drain pit is cleaned. It would be desirable to produce a
system that can be installed in the ground quickly and flexibly, minimising
disruption, while also reducing the area of the street/ground that has to be
15 excavated.
It would be desirable to produce a system in which filtered storm
water can be stored locally, and used on site (for example to water nearby
plants) or transferred to the surrounding ground (i.e. an infiltration
system). It
would be desirable to produce a filter for a storm water drain pit system
which
has equivalent or improved filtration in comparison to existing filtering
systems
20 i.e. can
remove the same or more pollutants, contaminants, particulates and
debris, while also being less likely to get clogged or blocked. Furthermore,
it
would be desirable to produce a filter system for a storm water drain pit
which is
environmentally acceptable and economical in terms of production, installation
and use. It would be advantageous to have a system in which the storm water
25 collection
system, especially an infiltration system, is protected from pollutants,
contaminants, particulates and debris so that it does not need to be
periodically
dug up and replaced or cleaned. This is particularly the case when the storm
water filtration system is located in an urban or industrial area were
rainwater
can be contaminated with man-made material that should be prevented from
30 entering
the ground or waterways for environmental reasons. The present
invention solves these problems.
Summary of the invention
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According to a first aspect of the invention, there is provided a storm water
filtration system comprising:
(i) a storm water drain pit (12);
5 (ii) a filtering well (1) for filtering storm water;
(iii)
a storm water collection system (7) for storing filtered storm water;
wherein the filtering well comprises;
an inlet (2) for storm water to enter the filtering well; wherein the inlet
(2) is in
fluid communication with the storm water drain pit;
10 an outlet
(3) for filtered storm water to exit the filtering well; wherein the outlet
(3)
is in fluid communication with the storm water collection system (7);
a filter (4) comprising man-made vitreous fibres (MMVF) for removing particles
from the storm water, wherein the filter (4) divides the filtering well (1)
into an
inlet chamber (5) and an outlet chamber (6) such that storm water enters via
the
15 inlet (2)
into the inlet chamber (5), passes through the filter (4) into the outlet
chamber (6) and exits via the outlet (3).
According to a second aspect of the invention, there is provided a method of
filtering and storing storm water comprising the steps of:
20 - providing a storm water filtration system as described above and
herein;
- allowing storm water to enter the storm water drain pit for coarse
filtration;
- allowing water to flow from the storm water drain pit into the inlet
chamber
(5) of the filtering well (1) via the inlet (2);
- allowing the storm water to pass from the inlet chamber (5) to the outlet
25 chamber (6) through the filter (4);
- allowing the filtered storm water to exit the filtering well via the
outlet (3)
into the storm water collection system (7) for storage.
According to a third aspect of the invention, there is provided a method of
30 installing a storm water filtration system, comprising the steps of;
- identifying a storm water drain pit in the ground or positioning a storm
water drain pit in the ground;
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- positioning a filtering well in the ground, wherein the filtering well
comprises;
an inlet (2) for storm water to enter the filtering well; wherein the inlet
(2) is in
fluid communication with the storm water drain pit;
5 an outlet (3) for filtered storm water to exit the filtering well;
a filter (4) comprising man-made vitreous fibres (MMVF) for removing particles
from the storm water, wherein the filter (4) divides the filtering well (1)
into an
inlet chamber (5) and an outlet chamber (6) such that storm water enters via
the
inlet (2) into the inlet chamber (5), passes through the filter (4) into the
outlet
10 chamber (6) and exits via the outlet (3);
- positioning a storm water collection system in ground, wherein the outlet
(3) of the filtering well is in fluid communication with the storm water
collection system (7).
15 The inventors discovered that a storm water drain system according to
the
present invention solves the above described problems.
The filtering well can be connected to a standard storm water drain pit,
already
present in the ground. Storm water therefore enters the standard storm water
20 drain pit which preferably comprises a sand trap and a leaf catcher.
Coarse
filtration of e.g. leaves, twigs and sand occurs and the water is then
directed into
the filtering well, where finer filtration occurs through the MMVF filter.
Once the
water is filtered through the MMVF filter, it can then be directed to a storm
water
collection system for storage and later use, or infiltration into the
surrounding
25 ground. By decoupling the filtering well from the standard storm water
drain pit,
this means the filtering well does not need to be cleaned regularly. Instead,
the
storm water drain pit is cleaned in the usual manner (e.g. twice a year with
aggressive methods such as vacuum cleaning) and there is no danger of the
MMVF filter being damaged or any need for the MMVF filter to be removed. This
30 simplifies maintenance considerably which is highly desirable for local
councils/municipalities.
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Furthermore, the system of the present invention can prevent flooding and can
store water for later use or disposal based on infrastructure already in place
(i.e.
the standard storm water drain pit) with minimal disruption to the surrounding
ground during installation. The system is flexible and decentralised, which
5 means it
can be installed at specific sites, for example around one standard
storm water drain pit, rather than requiring an entire street to be excavated.
The
system can be installed under existing roads or pavements, again minimising
disruption during installation.
10 In one
embodiment, the filtering well has the combined purpose of filtration of
storm water and ventilation of a storm water collection system. Storm water
enters the filtering well, is filtered, and exits via an outlet to a storm
water
collection system. Air displaced from the storm water collection system, as
the
filtered water enters, passes into the filtering well. This allows for the
storm
15 water
collection system to fill quickly with water at times of heavy rainfall. It
also
maximises use of the storm water collection system by allowing the air to
escape
and water to take its place. Furthermore, it also reduces the disruption
caused
by installing water drainage and storm water collection systems in the ground,
by
combining two functions in one well.
Brief description of the figures
Figure 1 shows a side view of a storm water filtration system according to an
embodiment of the invention.
25 Figure 2
shows a top view of a storm water filtration system according to an
embodiment of the invention.
Figure 3 shows a filtering well for use in the invention.
Figure 4 shows a filtering well and a storm water collection system for use in
the
invention.
30 Figure 5
shows a storm water filtration system according to an embodiment of
the invention comprising:a storm water drain pit, a filtering well and a storm
water collection system.
Figure 6 shows a top view of a filtering well for use in the invention.
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Figure 7 shows a filter for use in the invention, comprising a frame and
guide.
Detailed description of the figures
5 Figure 1 shows a side view of a storm water filtration system according
to an
embodiment of the invention. Figure 1 shows a storm water filtration system
comprising a storm water drain pit (12); a filtering well (1) and a storm
water
collection system (7). In this embodiment, the storm water filtration system
is
located underground with the top surface of the storm water drain pit and the
top
10 surface of the filtering well at ground level. In use, water enters the
storm water
drain pit via an inlet in the top surface. The storm water is coarsely
filtered to
remove leaves, twigs and other large debris and channelled into the filtering
well
(1) via an inlet (2). The storm water then moves from the inlet chamber,
through
the filter, into the outlet chamber. The filtered water then exits the
filtering well
15 via the outlet (3) into the storm water collection system (7). The storm
water
collection system (7) is capable of storing a high volume of filtered water,
and is
preferably able to dissipate it into the surrounding ground (i.e. when acting
as an
infiltration system). As filtered water flows into the storm water collection
system
(7), air may leave via the air vent (8) into the filtering well. Figure 2
shows the
20 embodiment of Figure 1 from a top perspective.
Figure 3 shows a filtering well for use in an embodiment of the invention.
Storm
water enters the filtering well (1) via the inlet (2). The filtering well (1)
comprises
a filter (4) which is held in a frame (9) and divides the filtering well (1)
into an
25 inlet chamber (5) and an outlet chamber (6). Storm water passes through
the
filter (4) from the inlet chamber (5) to the outlet chamber (6) and then exits
via
the outlet (3). The filtering well (1) has a lid (11) which comprises a
perforation
(13). Air entering the filtering well (1) via the air vent (8) can pass out of
the
filtering well (1) via the perforation (13).
Figure 4 shows the filtering well (1) described above for Figure 3 in
combination
with a storm water collection system (7) for use in an embodiment of the
invention. Filtered storm water flows from the outlet (3) into the storm water
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collection system while air from the storm water collection system (7) passes
via
the air vent (8) into the filtering well (1).
Figure 5 shows the filtering well (1) and storm water collection system (7) of
5 Figure 4 in combination with a storm water drain pit (12). Water enters
the storm
water drain pit (12) via an inlet in the top surface. The storm water is
coarsely
filtered and then channelled into the filtering well (1) via an inlet (2). The
storm
water then moves from the inlet chamber (5), through the filter (4), into the
outlet
chamber (6). The filtered water then exits the filtering well (1) via the
outlet (3) in
10 to the storm water collection system (7). As filtered water flows into
the storm
water collection system (7), air leaves via the air vent (8) into the
filtering well
(1). This air can leave the filtering well (1) via the perforation (13) in the
lid (11).
Figure 6 shows a top view of a filtering well (1) for use in an embodiment of
the
15 invention. The filtering well (1) has a square base and the filter (4)
is positioned
diagonally to maximise its surface area, which in turn maximises the volume of
water that is able to pass through the filter in a given amount of time, i.e.
an
increased rate of filtration. The storm water enters via the inlet (2), moves
from
the inlet chamber (5), through the filter (4), into the outlet chamber (6) and
exits
20 the filtering well (1) via the outlet (3). Figure 6 shows an overflow
(14) for excess
filtered water to leave the filtering well (1), in times of high levels of
precipitation,
Figure 7 shows a filter for use in the invention, comprising a frame (9) and a
guide (10). In this embodiment, the frame (9) comprises mesh surrounding one
25 side face of the filter. Figure 7 shows a guide (10) for holding the
filter in position.
The guide secures the filter and frame (9) to the filtering well.
Detailed description
30 The invention relates to a storm water filtration system comprising:
(i) a storm water drain pit;
(ii) a filtering well for filtering storm water;
(iii) a storm water collection system for storing filtered storm water;
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wherein the filtering well comprises;
an inlet for storm water to enter the filtering well; wherein the inlet is in
fluid communication with the storm water drain pit;
an outlet for filtered storm water to exit the filtering well; wherein the
outlet
5 is in fluid communication with the storm water collection system;
a filter comprising man-made vitreous fibres (MMVF) for removing
particles from the storm water, wherein the filter divides the filtering well
into an inlet chamber and an outlet chamber such that storm water enters
via the inlet into the inlet chamber, passes through the filter into the
outlet
10 chamber and exits via the outlet.
A storm water filtration system according to an embodiment of the invention is
shown in Figures 1, 2 and 5.
15 The storm water filtration system is configured such that storm water
enters the
storm water drain pit and then flows from there into the filtering well, and
subsequently on to the storm water collection system. This indicates the flow
of
water through the filtration system, and hence its connectivity.
20 In this regard the storm water filtration system may be a self-contained
storm
water filtration system. This means that the storm water filtration system is
not
connected to a secondary system, such as a sewage system or other system
that discharges storm water.
25 A storm water drain pit (12) is an underground drain system in which
storm water
is coarsely filtered (to remove leaves, twigs, sand and other large debris)
and
channelled into the storm water system. Storm water drain pits are also called
storm water drains in the ground, gullies, catch basins or storm water inlets.
Typically a storm water drain pit is reached via a permeable grid in the
ground
30 i.e. a gridded drain cover which is normally a hinged lid.
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The term "filtering well" has Its normal meaning in the art. It is an
underground or
partially underground filter system for filtering storm water. It may also be
called
a filtering pit, chamber, basin or gully.
5 The term
"storm water" has its usual meaning in the art, and includes water from
precipitation such as rain, snow, sleet or hail and water run-off water from
residential and commercial areas.
One benefit of the present invention is that the filtering well can be
connected to
10 a standard
storm water drain pit already present in the ground. This minimises
disruption during installation.
Typically, storm water drain pits include a housing, comprising a bottom
surface,
one or more side surfaces, a hollow centre and a lid. It is a receptacle that
is
15 suitable
to be buried or partially buried in the ground. Typically, the housing is
made from concrete, plastic or cast-iron.
Preferably, the storm water drain pit includes an inlet. Preferably, the inlet
is an
aperture in the ground, under which the storm water drain pit is buried. The
inlet
20 may be any
shape i.e. circular, square, rectangular. Preferably, the inlet is
circular i.e. a circular hole in the ground leading to the storm water drain
pit.
Preferably the inlet of the storm water drain pit is integrated into the curb
of a
pavement or the gutter of a street.
25 Preferably
the inlet is covered with a lid. Preferably the lid is hinged such that it
can be opened and closed. This is also known as a drain cover. Preferably the
lid is a grid i.e. a cover with perforations. Storm water flows along gutters
on the
road or pavement, and enters the storm water drain pit, which is underground,
via the inlet. Therefore, the lid is permeable to allow water to pass through
the
30 inlet. The
lid can be any dimension suitable for covering the inlet. For example,
the lid may be 20 to 300 cm by 20 to 300 cm.
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Preferably the storm water drain pit includes a sedimentation chamber, such as
a sand trap. The sedimentation chamber is for sedimentation of debris which
passes through the inlet into the storm water drain pit. This debris may be
anything which passes into the storm water drain system e.g. sand, leaves,
twigs
5 and rubbish that might be left on the street, such as cigarette ends and
chewing
gum.
The sedimentation chamber is the volume in the storm water drain pit
that is below the outlet. The velocity of the water goes down in the storm
water
drain pit, thereby all the heavy particles drop to the bottom and form a
sedimentation.
Preferably the storm water drain pit comprises an outlet. Preferably the
outlet is
separated from the sedimentation chamber. Preferably the outlet is positioned
above the sedimentation chamber and below the inlet. The outlet conveys water
to the inlet of the filtering well, and as such, is in fluid communication
with the
15 inlet of the filtering well.
Preferably the storm water drain pit includes a leaf catcher. The leaf catcher
may be a perforated plate that covers the outlet. The leaf catcher thus
prevents
large pieces of debris, such as leaves, from flowing out of the outlet. The
20 perforated plate may be formed of metal, plastic or the like.
In this way, the filtering well and filtration system can be connected to an
existing
storm water drain pit in the ground. The storm water drain pit coarsely
filters the
storm water by removing leaves, twigs and other large debris. The storm water
is
25 then conveyed to the filtering well where finer filtration occurs, as
will be
described below. The filtered storm water can then be stored in a storm water
collection system. One benefit of this system is that the storm water drain
pit
can be cleaned as normal, for example every six months with a vacuum cleaner,
without the MMVF filter being damaged or having to be removed, since it is in
a
30 separate filtering well. Furthermore, the filtering well and storm water
collection
system may be installed under roads or pavements, beside existing storm water
drain pits. This minimises disruption during installation.
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The filtering well (1) is formed of a housing comprising a bottom surface, one
or
more side walls, a hollow centre and a top surface which may comprise a lid.
The filtering well is a receptacle suitable for being buried or partially
buried in the
ground. Preferably the filtering well housing is formed of concrete, plastic
or
5 cast-iron.
The housing of the filtering well may be any shape, but preferably it is
in the shape of a cylinder, cube or cuboid. When the housing is in the shape
of a
cuboid, preferably the bottom surface of the housing is square. A filtering
well is
shown in Figure 3 (side view) and Figure 6 (top view).
10 Preferably
the filtering well is at least partially buried within the ground.
Preferably the filtering well is buried in the ground such that the top
surface is at
ground level i.e. is accessible from the ground.
The top surface preferably comprises a lid (11) to provide ventilation as well
as
15 access to
the filtering well from ground level. The lid is preferably formed of cast
iron, plastic or concrete. Preferably the lid is installed in a position in
the ground
where water does not collect ¨ such as in a pavement. The lid may be
impermeable to water along its top face, and allow air to leave the filtering
well at
the side faces (for example through one or more apertures or perforations
13)).
20 This
ensures that only a very small (i.e. negligible) volume of water can enter the
filtering well via lid. A perforation (13) is shown in Figures 3 and 5.
The top surface of the filtering well may be partially covered with earth
and/or
conventional road or pavement materials. The term earth may include sediment,
25 sand,
clay, dirt, gravel and the like. Conventional road or pavement materials
may include tarmac, asphalt, bitumen, macadam, cobblestones, gravel,
sandstone, concrete and the like. However, it is beneficial that the lid of
the
filtering well is accessible so that the filter may be changed when it becomes
soiled/contaminated. This helps to maintain suitable flow of storm water
through
30 the
system, whilst protecting the storm water collection system from debris and
contaminants.
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Preferably, the filtering well is positioned in the ground beside the storm
water
drain pit. Preferably the filtering well is within 0.2 m to 5 m of the storm
water
drain pit.
5 The
filtering well comprises an inlet (2) for storm water to enter the filtering
well.
Preferably the inlet is the principle route through which storm water can
enter the
filtering well. The filtering well may contain more than one inlet. The
diameter of
the inlet may be any size that is capable of being connected to standard
sewage
pipes. Preferably the inlet has an opening with a diameter in the range of
10 100 mm to
160 mm, more preferably 110 mm to 125 mm. Preferably the inlet is
positioned in a side surface of the housing of the filtering well, at a height
that is
lower than the top of the filter. This prevents the risk of incoming storm
water
spilling over the filter. Preferably the inlet is positioned in the lower half
of the
filtering well side surface, when in use.
In use, the filtering well is buried or partially buried underground, so it is
preferred that the inlet is in fluid communication with a conduit which brings
storm water to the inlet. The conduit may be an open channel, and water may
flow along this channel into the filtering well. Preferably the conduit is a
pipe. An
20 advantage
of a pipe is that it is hollow and can therefore freely transport water
underground to the filtering well. Further, the wall of the pipe prevents
debris
from entering the pipe.
The inlet of the filtering well is in fluid communication with the storm water
drain
25 pit.
Preferably, the inlet of the filtering well is in fluid communication with the
outlet of the storm water drain pit. This can be achieved by use of a conduit,
as
described above.
In this way, storm water first enters the storm water drain pit where debris,
such
30 as leaves,
twigs any coarse particles from the roads, sand, gravel or the like, is
removed for example through the use of a sedimentation chamber and/or leaf
catcher. The storm water then flows through the outlet of the storm water
drain
pit into the inlet of the filtering well.
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The filtering well comprises an outlet (3) for filtered storm water to exit
the
filtering well. In one embodiment, the outlet is the only route through which
filtered storm water can exit the filtering well. In another embodiment, the
5 filtering
well may contain more than one outlet. For example, the filtering well
according to the present invention may comprise an overflow (14), which can be
seen in Figure 6. The overflow is configured such that excess water can flow
out
of the filtering well. Preferably the overflow is positioned in the outlet
chamber,
such that excess filtered water flows out of the filtering well. Preferably
the
10 overflow
is positioned higher than the outlet (3) so that filtered water first exits
via the outlet. The overflow can be connected to any system for handling
excess
water, such as a mains sewer system.
Preferably the outlet has an opening with a diameter in the range of 100 mm to
15 160 mm, more preferably 110 mm to 125 mm. Preferably
the outlet is
positioned in a side surface of the housing of the filtering well. Preferably
the
outlet is positioned in the lower half of the filtering well side surface,
when in use.
This minimises the amount of water that collects, and stagnates in the well.
20 The outlet
is in fluid communication with a storm water collection system. In use,
the filtering well is buried or partially buried underground, so it is
preferred that
the outlet is in fluid communication with a conduit through which filtered
storm
water flows to the storm water collection system. Preferably the conduit is a
pipe. An advantage of a pipe is that it is hollow and can therefore freely
25 transport
filtered storm water to the storm water collection system. Further, the
wall of the pipe prevents debris from entering the pipe.
The filtering well comprises a filter (4) that divides the filtering well (1)
into an
inlet chamber (5) and an outlet chamber (6). This can be seen in Figures 3 and
30 5. The
inlet chamber contains the inlet, and as such, storm water enters the
filtering well by flowing from the storm water drain pit through the inlet of
the
filtering well into the inlet chamber. The inlet chamber and the outlet
chamber
are separated by the filter, such that water must pass through the filter in
order to
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move from the inlet chamber to the outlet chamber. The outlet chamber contains
the outlet, and as such, filtered storm water flows from the outlet chamber
through the outlet.
5 Preferably
the filter extends along the bottom surface of the filtering well, from
one side surface to an opposing side surface thus dividing the filtering well
into
two separate chambers. In one embodiment, when the housing of the filtering
well is cylindrical, the filter extends across the diameter of the filtering
well. In
another embodiment, when the housing of the filtering well is a cube or
cuboid,
10 the filter
extends diagonally from one corner to a diagonally opposing corner.
This maximises the surface area of the filter and therefore improves the rate
of
filtration and water flow.
The filter comprises man-made vitreous fibres (MMVF). A filter comprising
15 MMVF is
particularly advantageous because it is a sustainable material that can
be recycled; it has a very fine pore structure, which means it can filter very
fine
particles; and it maintains the required flow capacities even when polluted
(from
filtration). Preferably the filter comprises coherent man-made vitreous fibres
(MMVF) bonded with a cured binder composition. By this it is meant that the
filter
20 is in the
form of a coherent mass of MMVF i.e. a MMVF substrate or slab. That
is, the filter is generally a coherent matrix of MMVF fibres bonded with a
cured
binder composition, which has been produced as such, or has been formed, for
example, by granulating a slab of MMVF and consolidating the granulated
material. A coherent substrate is a single, unified substrate.
In an alternative embodiment, the filter may comprise granules and/or cubicles
of
MMVF bonded with a cured binder composition. In this embodiment, the filter is
made by packing the granules or cubicles into a filter frame.
30 In an
alternative embodiment, the filter may comprise loose MMVF, for example
loose mineral wool, without a cured binder composition. In this embodiment,
the
filter is made by packing the loose MMVF in a filter frame.
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The man-made vitreous fibres (MMVF) can be glass fibres, ceramic fibres,
basalt fibres, slag wool, stone wool and others, but are usually stone wool
fibres.
Stone wool generally has a content of iron oxide at least 3% and content of
alkaline earth metals (calcium oxide and magnesium oxide) from 10 to 40 /0,
5 along with the other usual oxide constituents of MMVF (e.g. silica and
alumina).
The stone wool generally comprises alkali metals (sodium oxide and potassium
oxide), in the range of 1% to 20 %. The stone wool may also include titania
and
other minor oxides.
10 Stone fibres commonly comprise the following oxides, in percent by
weight:
SiO2: 30 to 51
A1203: 12 to 30
CaO: 8 to 30
15 Mg0: 2 to 25
FeO (including Fe2O3): 2 to 15
Na20+K20: not more than 10
Ca0+Mg0: 10 to 30
20 In preferred embodiments the MMVF have the following levels of elements,
calculated as oxides in wt%:
SiO2: at least 30, 32, 35 or 37; not more than 51, 48, 45 or 43
A1203: at least 12, 16 or 17; not more than 30, 27 or 25
25 CaO: at least 8 or 10; not more than 30, 25 or 20
MgO: at least 2 or 5; not more than 25, 20 or 15
FeO (including Fe2O3): at least 4 0r5; not more than 15, 12 or 10
Fe0+Mg0: at least 10, 12 or 15; not more than 30, 25 or 20
Na20+K20: zero or at least 1; not more than 10
30 Ca0+Mg0: at least 10 or 15; not more than 30 or 25
TiO2: zero or at least 1; not more than 6, 4 or 2
Ti02-FFe0: at least 4 or 6; not more than 18 or 12
B203: zero or at least 1; not more than 5 or 3
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P205: zero or at least 1; not more than 8 or 5
Others: zero or at least 1; not more than 8 or 5
The MMVF made by the method of the invention preferably have the
5 composition in wt%:
SiO2 35 to 50
A1203 12 to 30
TiO2 up to 2
10 Fe2O3 3 to 12
Ca0 5 to 30
MgO up to 15
Na2O 0 to 15
K20 0 to 15
15 P205 up to 3
MnO up to 3
6203 up to 3
Another preferred composition for the MMVF is as follows in wt%:
SiO2 39-55% preferably 39-52%
A1203 16-27% preferably 16-26%
Ca0 6-20% preferably 8-18%
MgO 1-5% preferably 1-4.9%
25 Na2O 0-15% preferably 2-12%
K20 0-15% preferably 2-12%
R20 (Na2O + K20) 10-14.7% preferably 10-13.5%
P205 0-3% preferably 0-2%
Fe2O3 (iron total) 3-15% preferably 3.2-8%
30 B203 0-2% preferably 0-1%
TiO2 0-2% preferably 0.4-1%
Others 0-2.0%
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Glass fibres commonly comprise the following oxides, in percent by weight:
SiO2: 50 to 70
A1203: 10 to 30
5 CaO: not more than 27
MgO: not more than 12
Glass fibres can also contain the following oxides, in percent by weight:
Na20+K20: 8 to 18, in particular Na20+K20 greater than Ca0+Mg0
B203: 3 to 12
Some glass fibre compositions can contain A1203: less than 2%.
The geometric mean fibre diameter is often in the range of 1.5 to 10 microns,
in
particular 2 to 8 microns, preferably 2 to 5 microns. The inventors found that
this
15 range of geometric fibre diameter positively affects capillarity thus
improving
filtration.
Preferably, the filter has a density in the range of 40 to 250 kg/m3. This
density
range ensures that the filter has sufficient strength whilst also having
sufficient
20 filtering capacity i.e. the speed at which water can pass through the
MMVF filter.
If the density is too high, the filter will be strong but will have a lower
filtering
capacity. Equally, if the density is too low, the filter will not have
sufficient
strength during use
25 Preferably, when the filter comprises coherent man-made vitreous fibres
(MMVF)
bonded with a cured binder composition, the density is in the range of 75 to
200 kg/m3 more preferably 100 to 160 kg/rn3.
Preferably, when the filter comprises granules and/or cubicles of MMVF bonded
30 with a cured binder composition or loose MMVF, such as loose mineral
wool
without a cured binder composition, the density is in the range of 40 to 250
kg/m3, more preferably 40 to 150 kg/m3. For example, the granulate may be
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packed to a density of 60 to 80 kg/m3, and the cubicles may have a density of
50
to BO kg/m3.
Preferably, the filter has a binder content in the range of 0% to 10 /0,
preferably
5 1% to 10%,
more preferably 2% to 5%. This ensures filter is rigid and self-
supporting in the sense it can remain upright when positioned in use.
Preferably, when the filter comprises coherent man-made vitreous fibres (MMVF)
bonded with a cured binder composition or granules and/or cubicles of MMVF
10 bonded
with a cured binder composition, the binder content is in the range of 1%
to 10%, more preferably 2% to 5%.
Preferably when the the filter comprises loose MMVF, there is no binder
composition present, so the binder content is 0%.
The binder can be an organic hydrophobic binder, and in particular it can be a
conventional heat-curable (thermosetting), binder of the type which has been
used for many years in MMVF substrates (and other MMVF-based products).
This has the advantage of convenience and economy. Thus, the binder is
20 preferably
a phenol formaldehyde resin or urea formaldehyde resin, in particular
phenol urea formaldehyde (PUF) resin.
The binder may be a formaldehyde-free binder, for example it may comprise a
sugar, a furan, a lignin, a hydrocolloid, a carbohydrate, an amine, sulfamic
acid
25 or the
like as a main component. The formaldehyde-free binder may be as
described in any of the following publications: W02004/007615, W097/07664,
W007129202, W02017/114724, W02017/114723 or W02020/070337.
Preferably, the filter is hydrophilic, that is, it does not repel water.
Hydrophilic
30 has its
normal meaning in the art. An advantage of the filter being hydrophilic is
that water passes through the filter at a high speed, increasing the
filtration
capacity of the filter. In a preferred embodiment, the rate of flow of water
is up to
10 litres per second.
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The hydrophilicity of the filter may be defined in terms of the contact angle
with
water. Preferably, the MMVF of the filter has a contact angle with water of
less
than 900. The contact angle is measured by a sessile drop measurement
5 method.
Any sessile drop method can be used, for example with a contact angle
gonionneter. In practice, a droplet is placed on the solid surface and an
image of
the drop is recorded in time. The static contact angle is then defined by
fitting
Young-Laplace equation around the droplet. The contact angle is given by the
angle between the calculated drop shape function and the sample surface, the
10 projection
of which in the drop image is referred to as the baseline. The
equilibrium contact angles are used for further evaluation and calculation of
the
surface free energy using the Owens, Wendt, Rabe! and Kaeble method. The
method for calculating the contact angle between material and water is well-
known to the skilled person.
Hydrophilicity of the filter may be defined by the hydraulic conductivity.
Preferably, the filter has a hydraulic conductivity of 5 m/day to 300 m/day,
preferably 50 m/day to 200 m/day. Hydraulic conductivity is measured in
accordance with ISO 17312:2005. The advantage of this hydraulic conductivity
20 is that
the filter can filter water and transfer it away with sufficient speed to
prevent flooding.
The hydrophilicity of a sample of MMVF substrate can be measured by
determining the sinking time of a sample. A sample of MMVF substrate having
25 dimensions
of 100x100x15 mm to 100x100x100 mm is required for determining
the sinking time. A container with a minimum size of 200x200x200 mm is filled
with water. The sinking time is the time from when the sample first contacts
the
water surface to the time when the test specimen is completely submerged. The
sample is placed in contact with the water in such a way that a cross-section
of
30 100x100 mm
first touches the water. The sample will then need to sink a
distance of just over the height of the sample in order to be completely
submerged. The faster the sample sinks, the more hydrophilic the sample is.
The MMVF substrate is considered hydrophilic if the sinking time is less than
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240 s. Preferably the sinking time is less than 100 s, more preferably less
than
60 s, most preferably 50 s. In practice, the MMVF substrate may have a sinking
time of 50 s or less.
5 Preferably, the filter is free from oil or substantially free from oil.
Preferably, the
filter is substantially free from oil. By this, it is meant that the filter
comprises
only trace amounts of oil, for example less than 0.1 wt% of oil. Most
preferably
the filter is free from oil. By this it is meant that the filter has 0 wt% of
oil. Oil is
typically added to MMVF substrates which are to be used for purposes such as
10 sound, insulation, thermal insulation and fire protection. However, the
filter is
sufficiently hydrophilic to absorb and drain water when it is free from oil or
substantially free from oil. In this embodiment, the binder composition may be
hydrophilic or hydrophobic, as discussed above. Preferably, when the binder
composition is hydrophobic, the filter is free from or substantially free from
oil.
The filter may be self-supporting and therefore can be positioned in the
filtering
well without the requirement for a supporting frame or guide to hold the
filter in
place.
20 In a preferred embodiment, the filtering well further comprises a frame
(9) for
supporting the filter. This can be seen in Figures 3, 5 and 7. The frame may
be
any material that is capable of supporting the filter, without preventing the
filter
from functioning i.e. filtering the storm water. For example, the frame may
comprise mesh or netting, preferably metal mesh or stretch metal netting. The
25 frame may surround part of the filter, or may surround all faces of the
filter.
In a preferred embodiment, the frame may be a U-shape in which the filter
sits.
By this, it is meant that the frame surrounds the outer perimeter (i.e. edges)
of
the filter at the sides and the bottom. This ensures that the two faces with
the
30 largest surface areas (i.e. the front face which faces the inlet and the
back face
which faces the outlet) are not covered by the frame, and thus filtration is
optimised.
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In an alternative embodiment, the frame surrounds at least part of the back
face
of the filter i.e. the face on the side of the outlet. This provides support
that
resists the direction of flow of water, thus preventing any breakage to the
filter.
In this embodiment, the frame is preferably a mesh or netting.
Preferably, the frame comprises a hinge which allows the frame to be opened.
This ensures that it is easy to maintain or replace the filter held with the
frame.
Irrespective of the form of the MMVF material, i.e. granules, cubicles, loose
or
coherent MMVF, and irrespective of whether the MMVF is bonded, it is
particularly beneficial that the filter is easily removable from the filtering
well so
that it may be replaced when sufficiently fouled. A key benefit of the filter
in this
case is to protect the storm water collection system from debris and
contaminates. This is because the storm water collection system is typically
buried underground and therefore it cannot easily be maintained or replaced.
Having a removable MMVF filter that is separate to the storm water collection
system means that it protects the collection system from contamination. This
is
particularly important when the storm water protection system is an
infiltration
system, and even more so when the infiltration system comprises drain elements
formed from MMVF as discussed below. In this case, the filter protects the
MMVF drain elements from fouling and contamination, and the surrounding
ground from pollution. Having a separate filter is also important when the
storm
water filtration system is a self-contained storm water filtration system.
In a preferred embodiment, the filtering well further comprises a guide (10)
for
holding the filter in position. The guide secures the filter, which may or may
not
comprise a frame, to the filtering well. For example, the guide may be a rail
into
which the filter or filter and frame can be inserted. One of the advantages of
the
filtering well comprising a guide is that the guide may act as a seal between
the
the edge of the filter or frame, and the sides of the filtering well. This
reduces
leakages around the edges of the filter (or frame), so that water (and dirt,
particulates and contaminates) cannot leak from the input chamber into the
output chamber without passing through the filter. This may ensure that all or
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most of the storm water passes through the filter and all or most of the water
is
thus filtered and the particulates and pollutants are removed. The guide may
also facilitate ease of removal and replacement of the filter.
5 The filtering well according to the present invention optionally
comprises an air
vent (8) that is in fluid communication with a storm water collection system,
such
that air displaced from the storm water collection system passes into the
filtering
well. This can be seen clearly in Figures 3, 4 and 5. The filtering well may
contain more than one air vent. Preferably the air vent has an opening with a
10 diameter in the range of 40 to 125 mm Preferably the air vent is
positioned in a
side surface of the housing of the filtering well, preferably in the outlet
chamber
section. Preferably the air vent is positioned higher in the filtering well
than the
outlet. Preferably the air vent is positioned in the top half of the filtering
well side
surface, when in use. This ensures that the air vent can function even when
the
15 level of water in the filtering well is high.
Including the air vent in the filtering well is advantageous, as it combines
two
functions in one well: filtration and ventilation. By allowing air to pass
from the
storm water collection system to the filtering well, this maximises the amount
of
20 water that can be stored in the storm water collection system.
Furthermore, this
simplifies installation of the filter well and infiltration system, which
means less
disruption. The air vent can also enable high flow rates through both the
filter as
well as the collection system.
25 In use, the filtering well is buried or partially buried underground, so
it is
preferred that the air vent is in fluid communication with a conduit through
which
air from the storm water collection system can flow into the filtering well.
Preferably the conduit is a pipe. An advantage of a pipe is that it is hollow
and
can therefore freely transport air from the storm water collection system.
30 Further, the wall of the pipe prevents debris from entering the pipe.
The term "storm water collection system" has its normal meaning in the art. A
storm water collection system is capable of absorbing and storing water. A
storm
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water collection system can also transfer the stored water to a water
collection
point, for use of disposal, or infiltrate into the surrounding ground.
The storm water collection system may be any system known to the skilled
5 person. It may be any system that is capable of absorbing and storing
water.
For example, in a preferred embodiment, it may be an infiltration system that
absorbs water and then allows it to infiltrate into the surrounding ground. It
may
be a water buffer that absorbs water and holds it until it can be discharged
later.
10 In one embodiment, the storm water collection system may comprise one or
more pipes. In one embodiment, the one or more pipes may go further
underground than the filtering well, for example 1m to 100 m underground, so
that the water can be transferred into ground that is suitable for
infiltration. This
may be useful when the top layer of the ground has high amounts of clay, which
15 is unsuitable for infiltration.
In another embodiment, the storm water collection system may comprise a
granular material, such as gravel or lava. The void space between the granular
material is capable of holding water. The benefit of this is that the granular
20 material is very flexible to install, and can be made into any desired
shape.
In another embodiment, the storm water collection system may comprise a
receptacle, such as a plastic box, optionally wrapped in geotextile fabric.
25 In a preferred embodiment, the storm water collection system comprises
one or
more drain elements, wherein the drain element comprises man-made vitreous
fibres bonded with a cured binder composition. The benefit of this storm water
collection system is that the drain elements are able to store a high volume
of
water, much higher than gravel or lava, within the MMVF open pore structure.
30 Furthermore, as the surrounding ground dries out, the water gradually
dissipates
from the MMVF drain elements into the ground. This provides an effective way
to dispose of storm water. Finally, MMVF drain elements are flexible to
install,
as they can easily be cut on site to any desired shape.
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The MMVF drain elements may be as described in W02013/113410 or
W02013/072082.
5
W02013/113410 describes a drain element formed of a hydrophilic coherent
man-made vitreous fibre substrate (MMVF substrate), wherein the MMVF
substrate comprises man-made vitreous fibres bonded with a cured binder
composition, the MMVF substrate having opposed first and second ends and a
passage which extends from a first opening in the first end to a second
opening
10 in the second end.
W02013/072082 describes a water drain reservoir comprising a coherent man-
made vitreous fibre substrate (MMVF substrate) and a conduit having two open
ends, wherein the MMVF substrate comprises man-made vitreous fibres bonded
15 with a
cured binder composition, wherein a first open end of the conduit is in fluid
communication with the MMVF substrate.
In view of the above and the purpose of the invention, a particularly
preferred
embodiment of the invention is a storm water filtration system, comprising:
20 (i) a storm water drain pit (12);
(ii) a filtering well (1) for filtering storm water;
(iii) a storm water collection system (7) for storing filtered storm water,
wherein the storm water collection system is an infiltration system
that allows the filtered storm water to infiltrate into surrounding
25 ground;
wherein the filtering well comprises;
an inlet (2) for storm water to enter the filtering well; wherein the inlet
(2)
is in fluid communication with the storm water drain pit;
an outlet (3) for filtered storm water to exit the filtering well; wherein the
30 outlet (3)
is in fluid communication with the storm water collection system
(7);
a filter (4) comprising man-made vitreous fibres (MMVF) for removing
particles from the storm water, wherein the filter (4) divides the filtering
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well (1) into an inlet chamber (5) and an outlet chamber (6) such that
storm water enters via the inlet (2) into the inlet chamber (5), passes
through the filter (4) into the outlet chamber (6) and exits via the outlet
(3)-
The above storm water filtration system may be a self-contained storm water
filtration system. This means that it does not need to be connected to a
secondary system, such as a sewage system or other system that discharges
storm water. The filter may be easily removed from the self-contained unit to
be
replaced or cleaned.
In a preferred embodiment, the above storm water filtration system comprising
an infiltration system comprises one or more drain elements, wherein the drain
element comprises man-made vitreous fibres bonded with a cured binder
composition.
The above storm water filtration system comprising an infiltration system may
be
beneficial due to the filter being able to remove pollutants, contaminants,
particulates and debris from the storm water, before the filtered water is
dissipated into the surrounding ground, which reduces the potential for ground
pollution. This may be particularly beneficial in urban areas, including
industrial
areas, where pollution from pollutants, contaminants, particulates and debris,
is
likely to be more prevalent in the storm water.
In this case it is preferred that the filter in the filtering well is
removable and
replaceable. This means that it can be removed and replaced when it has
become fouled as it protects the storm water collection system (especially an
infiltration system) from debris or contamination. Again, this is particularly
advantageous as the storm water collection system is typically buried
underground and would be difficult to clean and need to be excavated if it is
to
be replaced. The filter may be referred to as a sacrificial filter. To achieve
this
the filtering well may comprise a guide (10) for holding the filter in
position. The
guide secures the filter, which may or may not comprise a frame, to the
filtering
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well. For example, the guide may be a rail into which the filter or filter and
frame
can be inserted.
The binder composition in the drain element may be as described above for the
5 filter.
The storm water collection system preferably comprises an air vent. Preferably
the air vent is an aperture through which air that is displaced as water
enters the
storm water collection system can exit. Preferably the air vent is formed by
10 inserting a pipe from ground level into the storm water collection
system.
In a preferred embodiment, the outlet of the filtering well is connected to a
MMVF drain element via a conduit, preferably a pipe. An MMVF drain element
can butt up against the conduit, preferably a pipe, through which filtered
storm
15 water will flow, in order to achieve this fluid communication. It is
preferable
however for efficiency for the conduit to be at least partially embedded into
the
MMVF drain element. The embedded part of the conduit may have an aperture
in its outer wall, preferably more than one aperture. The presence of an
aperture has the advantage of there being a greater area through which the
20 water can flow into the drain element.
The MMVF drain element may have a passagelch extends from a first end of the
drain element, towards a second end of the drain element, wherein the first
and
second ends are opposed and wherein the first end of the passage is in fluid
25 communication with water from filtering well. The passage may extend 10%
to
100 % of the way through the drain element, preferably 20 % to 99 % of the way
through the drain element, preferably 50% to 99 % of the way through the drain
element, more preferably 80 A) to 95 % of the way through the substrate. The
advantage of the passage is that there is a greater area through which the
water
30 can flow into the drain element. The passage may have any cross-
sectional
shape, preferably circular, triangular or square.
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The storm water collection system may comprise more than one drain element,
preferably a series of drain elements, which may be connected together to
increase the volume of water that can be stored and then dissipated. These
drain elements may be placed next to each other so that water can dissipate
5 from one drain element to the next. Alternatively, a conduit, preferably
a pipe,
with apertures can run through a first drain element, and then be at least
partially
embedded into a second drain element. This allows any water which is not
absorbed by the first drain element to flow into the second drain element and
so
on, for any further drain elements in the storm water collection system.
Preferably the water holding capacity of the drain element is at least 80% of
the
volume, preferably 80-99 %, most preferably 85-95 %. The greater the water
holding capacity, the more water that can be stored for a given volume. The
water holding capacity of the drain element is high due to the open pore
15 structure of MMVF.
Preferably the amount of water that is retained by the drain element when it
gives off water is less than 20 %vol, preferably less than 10 %vol, most
preferably less than 5%vol. The water retained may be 2 to 20 %vol, such as 5
20 to 10 %vol. The lower the amount of water retained by the drain element,
the
greater the capacity of the drain element to take on more water. Water may
leave the drain element by dissipating into the ground when the surrounding
ground is dry and the capillary balance is such that the water dissipates into
the
ground.
Preferably the buffering capacity of the drain element, that is the difference
between the maximum amount of water that can be held, and the amount of
water that is retained when the drain element gives off water is at least 60
%vol,
preferably at least 70 %vol, preferably at least 80 %vol. The buffering
capacity
may be 60 to 90 %vol, such as 60 to 85 %vol. The advantage of such a high
buffering capacity is that the drain element can buffer more water for a given
volume, that is the drain element can store a high volume of water when it
rains,
and release a high volume of water as the surrounding ground dries out. The
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buffering capacity is so high because drain element requires a low suction
pressure to remove water from the drain element.
The water holding capacity, the amount of water retained and the buffering
5 capacity
of the drain element can be measured in accordance with EN 13041 ¨
1999.
The present invention also relates to a method of filtering and storing storm
water comprising the steps of:
10 - providing a storm water filtration system as described herein;
- allowing storm water to enter the storm water drain pit for coarse
filtration;
- allowing water to flow from the storm water drain pit into the inlet
chamber
of the filtering well via the inlet;
- allowing the storm water to pass from the inlet chamber to the outlet
15 chamber through the filter;
- allowing the filtered storm water to exit the filtering well via the
outlet into
the filtration system for storage.
The storm water filtration system may comprise any of the preferred features
20 discussed
above, in particular it is preferred that storage is in an infiltration
system (preferably infiltration system comprising MMVF as discussed above).
The present invention also relates to a method of installing a storm water
filtration system, comprising the steps of;
25 -
identifying a storm water drain pit in the ground or positioning a storm
water drain pit in the ground;
- positioning a filtering well in the ground, wherein the filtering well
comprises;
an inlet for storm water to enter the filtering well; wherein the inlet is in
fluid
30 communication with the storm water drain pit;
an outlet for filtered storm water to exit the filtering well;
a filter comprising coherent man-made vitreous fibres (MMVF) bonded with a
cured binder composition for removing particles from the storm water, wherein
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the filter divides the filtering well into an inlet chamber and an outlet
chamber
such that storm water enters via the inlet into the inlet chamber, passes
through
the filter into the outlet chamber and exits via the outlet;
- positioning a storm water collection system in ground, wherein the outlet
5 of the
filtering well is in fluid communication with the storm water
collection system.
The storm water filtration system may comprise any of the preferred features
discussed above, in particular it is preferred that the collection system is
an
10
infiltration system (preferably infiltration system comprising MMVF as
discussed
above).
Example
15 A storm
water filtration system according to the present invention was tested to
measure the water flow.
A pump with a capacity of 150-200 m3/hour was used to pump water via an inlet
into a storm water drain pit according to the present invention. From this
storm
20 water
drain pit, the water flowed directly to a filtering well with a filter
according
to the invention. Water then flowed through the filter and out through an
outlet.
The storm water drain pit and the filtering well had internal dimensions of
350x350x825mm. The filtering well had a water inlet (0 125mm) at 400 mm
25 (from
inside bottom), a 0 125mm drainpipe at 70 mm, an 0 125mm overflow at
400 mm from the bottom with siphon and a 0 50mm air vent in fluid
communication with a storm water collection system (comprising MMVF). The
filter, comprising MMVF bonded with a cured binder composition, measured
395x20x650 mm and was positioned diagonally in the filtering well. The filter
30 comprised
a stainless-steel holder frame. The input flow was measured in
m3/hour in relation to water level. A flow rate of 25 m3/hour was measured.
Numbered embodiments
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The following numbered embodiments provide further non-limiting embodiments
of the invention.
5 Embodiment 1. A filtering well (1) comprising:
an inlet (2) for storm water to enter the filtering well;
an outlet (3) for filtered storm water to exit the filtering well;
a filter (4) comprising man-made vitreous fibres (MMVF) for removing
particles from the storm water, wherein the filter (4) divides the filtering
10 well (1)
into an inlet chamber (5) and an outlet chamber (6) such that
storm water enters via the inlet (2) into the inlet chamber (5), passes
through the filter (4) into the outlet chamber (6) and exits via the outlet
(3);
wherein the outlet (3) is configured to be connectable to a storm water
15 collection system (7) for storing filtered storm water; and
an air vent (8) configured to be connectable to a storm water collection
system (7) such that air displaced from the storm water collection system
(7) passes into the filtering well via the air vent.
20 Embodiment
2. The filtering well (1) according to embodiment 1, wherein the
filter (4) has a density in the range of 40 to 250 kg/m3, preferably 75 to
200 kg/m3, more preferably 100 to 160 kg/m3.
Embodiment 3. The filtering well (1) according to embodiment 1 or 2, wherein
25 the man-
made vitreous fibres in the filter (4) have a geometric fibre diameter of
1.5 to 10 microns, preferably 2 to 8 microns, more preferably 2 to 5 microns.
Embodiment 4. The filtering well (1) according to any preceding embodiment,
wherein the filter comprises coherent man-made vitreous fibres (MMVF) bonded
with a cured binder composition.
Embodiment 5. The filtering well (1) according to any preceding embodiment,
wherein the filter (4) has a contact angle with water of less than 900 and/or
a
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hydraulic conductivity of 5 m/day to 300 m/day, preferably 50 m/day to 200
m/day.
Embodiment 6. The filtering well (1) according to any preceding embodiment,
5 wherein the filter (4) further comprises a frame (9) for support.
Embodiment 7. The filtering well (1) according to any preceding embodiment
further comprising a guide (10) for holding the filter (4) in position.
10 Embodiment 8. The filtering well (1) according to any preceding
embodiment in
the shape of a cylinder, cube or cuboid.
Embodiment 9. The filtering well (1) according to any preceding embodiment,
further comprising a lid (11), preferably wherein the lid comprises a water
15 impermeable top face and at least one perforation (13) at a side face.
Embodiment 10. The filtering well (1) according to any preceding embodiment
positioned under the ground, preferably under a road or pavement.
20 Embodiment 11. Use of a
filtering well (1) according to any preceding
embodiment for filtering storm water.
Embodiment 12. A method of filtering storm water comprising the steps of:
- providing a filtering well (1) according to any of embodiments 1 to 10;
25 - allowing
storm water to enter the filtering well (1) via the inlet (2) into the
inlet chamber (5);
- allowing the storm water to pass from the inlet chamber (5) to the outlet
chamber (6) through the filter (4) to produce filtered storm water;
- allowing the filtered storm water to exit the outlet chamber (6) via the
30 outlet (3).
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Embodiment 13.
A method of installing a filtration system comprising,
positioning at least one filtering well (1) according to any of embodiments 1
to 10
in the ground.
5 Embodiment 14. A storm water filtration system comprising:
(i) a filtering well (1) for filtering storm water:
(ii) a storm water collection system (7) for storing filtered storm water;
wherein the filtering well comprises;
an inlet (2) for storm water to enter the filtering well;
10 an outlet
(3) for filtered storm water to exit the filtering well; wherein the
outlet (3) is in fluid communication with the storm water collection system
(7);
a filter (4) comprising man-made vitreous fibres (MMVF) for removing
particles from the storm water, wherein the filter (4) divides the filtering
15 well (1)
into an inlet chamber (5) and an outlet chamber (6) such that
storm water enters via the inlet (2) into the inlet chamber (5), passes
through the filter (4) into the outlet chamber (6) and exits via the outlet
(3); and
an air vent (8) in fluid communication with the storm water collection
20 system (7)
such that air displaced from the storm water collection system
(7) passes into the filtering well via the air vent.
Embodiment 15. The storm water filtration system according to embodiment 14,
wherein the storm water collection system comprises one or more drain
25 elements,
wherein the drain element comprises man-made vitreous fibres
bonded with a cured binder composition.
Embodiment 16. A method of filtering and storing storm water comprising the
steps of:
30 - providing a storm water filtration system according to embodiment 14;
- allowing storm water to enter the filtering well (1) via the inlet
(2) into the
inlet chamber (5);
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- allowing the storm water to pass from the inlet chamber (5) to the outlet
chamber (6) through the filter (4);
- allowing the filtered storm water to exit the filtering well via the
outlet (3)
into the storm water collection system (7) for storage;
5 - allowing air displaced from the storm water collection system (7)
to pass
into the filtering well via the air vent (8).
Embodiment 17. A storm water filtration system comprising:
(i) a storm water drain pit (12);
10 (ii) a filtering well (1) for filtering storm water;
(iii) a storm water collection system (7) for storing
filtered storm water;
wherein the filtering well comprises;
an inlet (2) for storm water to enter the filtering well; wherein the inlet
(2)
is in fluid communication with the storm water drain pit;
15 an outlet (3) for filtered storm water to exit the filtering well;
wherein the
outlet (3) is in fluid communication with the storm water collection system
(7);
a filter (4) comprising man-made vitreous fibres (MMVF) for removing
particles from the storm water, wherein the filter (4) divides the filtering
20 well (1) into an inlet chamber (5) and an outlet chamber (6) such
that
storm water enters via the inlet (2) into the inlet chamber (5), passes
through the filter (4) into the outlet chamber (6) and exits via the outlet
(3); and
an air vent (8) in fluid communication with the storm water collection
25 system (7) such that air displaced from the storm water collection
system
(7) passes into the filtering well via the air vent.
Embodiment 18. The storm water filtration system according to embodiment 14,
15 or 17, wherein the storm water filtration system is a self-contained storm
30 water filtration system.
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