STORMWATER FILTRATION DEVICE

DISPOSITIF DE FILTRATION D'EAUX DE RUISSELLEMENT

English Abstract

A single tank for primary or inline treatment of stormwater runoff. The tank
consists of multiple concentric or eccentric compartments that are cylindrical
or
rectangular in shape. The inner compartment receives the untreated water
through a perforated catch-basin cover or an inline inlet pipe. The partially
treated water from this compartment, and any other compartment thereafter,
overflows into a receiving compartment that completely surrounds the source
compartment. The combination of gravity, density gradients, pipe siphon
arrangement and laminar flow conditions created by the shape of each of the
treatment compartment forces maximum separation of oils and sediments
without the need for moving parts or chemicals. A mixture of non compacted
oleophilic and oleophopic media is installed in the final compartment(s) to
coalesce residual free and partially emulsified oil droplets and separate them
from water. The media will also help knock out residual suspended solids.
Other
types of media like iron humate, Mica, sand, activated carbon or bacterial
growth
enhancing media can be used in conjunction of or instead of the oil-removal
media to remove other pollutants.

Claims

Claims
1. A multi-compartment stormwater filtration tank in which water is directed
to
flow from inner compartments to surrounding outer compartments.
2. A multi-compartment stormwater filtration tank as claimed in claim 1 in
which water is siphoned from a central location inside one compartment
then discharged near the bottom of the next surrounding compartment.
3. This allows only the least contaminated water from one compartment to
enter the next compartment and provides enough time for settleable solids
to settle to the bottom and free oils to float to the top of the receiving
compartment.
3. A multi-compartment stormwater filtration tank as claimed in claim 3 in
which the one-compartment-inside-the-other configuration promotes
increased separation of pollutants.
Water leaving one compartment has to travel to near the bottom of the
next surrounding compartment then travel upward and around the
circumference of the receiving compartment to the compartment's outlet
which is located at 180 degrees from the compartment's inlet. This
arrangement creates laminar flow patterns, prevents channeling and
maximizes the retention time of each droplet of water, droplet of oil and
particle of sediment. Therefore, increasing the amount of sediments that
drops to the bottom or oils that float to the top of each compartment.
4. A multi-compartment stormwater filtration tank as claimed in claim 3 that
incorporates the use of a mixture of oleophilic and oleophobic media to
coalesce residual oil and separate it from water just before said water is
discharged out of the treatment unit. The oleophilic media attracts residual
colloidal and partially emulsified oil droplets, while the oleophobic medial
repels these droplets towards the oleophilic media. Oil droplets that collect
on the surface of the oleophilic media will then coalesce and gain enough
buoyancy to float to the surface.

5. A multi-compartment stormwater filtration tank as claimed in claim 4 in
which water entering the last compartment is directed into an open space
below a none-compacted body of media, then flows upward through the
body of media. This arrangement helps knock out any remaining residual
solids back to the bottom of the compartment, without clogging up the
media.
6. A multi-compartment stormwater filtration tank as claimed in claim 5 in
which additional compartments can be added to treat higher stormwater
runoff flow rates or higher loads of pollutants.
7. A multi-compartment stormwater filtration tank as claimed in claim 6 in
which additional media can be added to treat different types of pollutants.
8. A multi-compartment stormwater filtration tank as claimed in claim 7 which
incorporates an overflow pipe arrangement that directs the overflow from
each compartment to the device's outlet without allowing the overflow
water to enter the other compartments. This pipe arrangement reduces
the chances of contaminating final compartments with untreated water
from previous compartments.
9. A multi-compartment stormwater filtration tank as claimed in claim 8 which
is manufactured in whole or in part from suitable concrete, metal or plastic
material or a mixture of suitable materials.
10. A multi-compartment stormwater filtration tank as claimed in claim 9 that
has three or more catch-basin access covers. When the device is used as
an inline filtration device, then all covers shall be solid. When the device
is
used a primary filtration device, then only the middle cover shall be
perforated so that untreated storm water enters the device from the
ground surface into the middle compartment.
11.A multi-compartment stormwater filtration tank as claimed in claim 10 in
which the entire pipe assembly can be cleaned from ground level by
pressurizing water from a clean water source or by vacuuming water
through the pipe assembly through pipe cleaning ports that are located
just below the catch-basin covers.
12.A multi-compartment stormwater filtration tank as claimed in claim 11 in
which the entire pipe assemblies are supported on removable plates that
are inserted inside slotted guides in the sides of the compartment walls.
The entire plate and pipe assembly can be removed so that the pipe
assembly can be inspected, cleaned, repaired or upgraded. The plate can
then be inserted back through the slotted guides.

Description

CA 02510476 2005-06-29
Description
A single tank that is designed for the removal of ffoatable, colloidal and
partially
emulsified oil as well as other floatable and perceptible material from
rainwater
(stormwater) runoff. The tank consists of multiple concentric or eccentric
compartments that are cylindrical or rectangular in shape. In a typical
compartment arrangement, stormwater runoff is received in the most inner
compartment, through a slotted catch-basin cover or through an inlet pipe. In
this
compartment, heavy sediment and trash fall to the bottom while lighter-than-
water objects and some free oils float to the surface. PartiaAy treated water
from
this compartment is siphoned from near the center of this compartment into the
bottom of the next surrounding outer compartment. In this compartment, water
as
well as any pollutants are forced to travel up and around the compartment's
circumference to its outlet which is located at 180 degrees from the inlet.
This
forces the water into a laminar flow pattern thus providing the conditions for
most
of the fine sediment to settle at the bottom and most of the remaining free
oil to
float to the top. Water from this compartment is then directed the same way
into
subsequent similar surrounding compartments. The number of these
compartments depends on the flow and/or the load of the pollutants to be
treated. The last compartment (or compartments) contains a mixture of
oleophilic and oleophobic media. The water enters this compartment through an
open space below the media. The water fills up this space all around the
compartment's circumference, then flows upward making direct contact with the
media. The oleophilic media attracts remaining colloidal and partially
emulsified
droplets of oil to its surface while the oleophobic media repels other oil
droplets
towards the oleophilic media. The oil droplets coalesce on the surfaces of the
oleophilic media then gain enough buoyancy to float to the surface. The

CA 02510476 2005-06-29
presence of the media and the upward flow pattern also forces residual fine
sediments to stay at the bottom of this compartment. Depending on desired
extent of treatment or stormwater flows, additional intermediary compartments
with or without media can be added. If the removal of other pollutants such as
dissolved hydrocarbons or phosphates is desired then other types of media such
as iron humate, Mica, sand, activated carbon or bacterial growth enhancing
media can be used. Treated water from the last outer compartment can be
directed to a stormwater pond, on-site stormwater detention or infiltration
arrangements, further on-site treatment steps or for direct discharge into a
natural water way.

CA 02510476 2005-06-29
LEGEND
1- Inlet pipe or opening
2- Most inner compartment
3- Surrounding outer compartments (one or more)
4- Siphon pipe arrangements
5- Treatment media -as described in text
6- Overflow pipe arrangement
7- Outlet pipe
8- Cleaning/ overflow ports
9- Solid or perforated catch-basin covers
10- Side view of removable pipe assembly