CA2510476A1

CA2510476A1 - Stormwater filtration device

Info

Publication number: CA2510476A1
Application number: CA 2510476
Authority: CA
Inventors: Hisham Younis
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-29
Filing date: 2005-06-29
Publication date: 2006-12-29

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.

Description

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 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.

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

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.