Abstract:
An insert for use in a sewer system to remove oils and solvents carried by surface water runoff. The insert includes a holder and a quantity of water permeable, hydrophobic, oil and solvent absorbing material such as melt blown polypropylene. The holder has two functions. It holds an effective quantity of the absorber and holds it in such a way that the surface water is exposed to the absorber to allow oils and solvents to be absorbed. The insert in preferably placed, cartridge-like, at the inlet or outlet of the sewer system so that it may be quickly checked, replaced and serviced. In one embodiment, the insert also contains a leaf trap.

Description:
CROSS REFERENCE TO RELATED PATENTS  
       [0001]     The present application is a divisional application of U.S. patent application Ser. No. 10/100,880, which claimed the priority of the provisional application Ser. No. 60/277,111 that was filed Mar. 19, 2001. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
       [0003]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0004]     The present invention relates to managing surface water generally and to pollution control and recycling more specifically.  
         [0005]     Sometimes when it rains, it pours. When it pours, leaves, dirt, debris, oils and solvents on the surfaces of roads and streets are swept by surface water runoff toward municipal sewer systems where this material may be collected and processed. Unfortunately, this material often flows directly into lakes or rivers. The surface water may enter the sewer system at inlets along a street curb or catch basin and exit the sewer system through large pipes. Oils and chemicals in the run off will contaminate the bodies of water into which they are dumped. This is referred to as “nonpoint source pollution” by some regulating authorities. A nonpoint source of pollution is basically pollution without a single point of origin, or pollution that is not introduced into a receiving body of water from a specific outlet. Some other examples of nonpoint sources may include agriculture, forestry, mining, construction, and land disposal. Because this type of pollution has no particular point of origin, it is not only difficult to collect this pollution, but is also difficult to monitor and prevent the pollution.  
         [0006]     Thus, there remains a need for a better way to manage the collection of the materials swept into the sewer system.  
       SUMMARY OF THE INVENTION  
       [0007]     According to its major aspects and briefly recited, the present invention is an insert to be placed into an inlet or outlet of a municipal sewer system. The insert comprises a holder such as a mesh bag or pillow and a water permeable, hydrophobic oil and solvent absorber carried by the holder. The holder will both hold a sufficient quantity of the absorber to be effective in absorbing oils and solvents for a suitable period of time but also to hold it in such a way as to expose it to the in-rushing or out-rushing surface water so that the absorber is exposed to the oil- and solvent-bearing surface water in order to extract at least a portion of the solvents and oils. In addition, the device may also include a trap for large particulate such as leaves and twigs.  
         [0008]     An important feature of the present invention is the use of a hydrophobic, water-permeable absorber. The absorber absorbs oils and solvents but not water, and it allows water to pass through readily. The absorber, moreover, can be cleaned and reused, and the solvent and oil recovered. Furthermore, the absorber can be tested for the presence of various chemicals that are absorbed as the water passes through it. This testing capability provides a convenient way to identify the chemical concentrations and flow rates for in-rushing and out-rushing surface water.  
         [0009]     Another important feature of the present invention is the holder. The holder, as noted above, serves two functions: it not only holds an effective quantity of the absorber, but it holds the absorber so that it is exposed to the in-rushing or out-rushing surface water so that the oils and solvents in the water can be absorbed. With the absorber in the holder, the insert becomes a convenient, replaceable, and recyclable cartridge for insertion into the inlet or outlet of the sewer system to absorb oils and solvents but readily pass the surface water.  
         [0010]     Still another feature of the invention is its placement. By being placed at the inlet or outlet of the sewer system, it is easily installed and removed, readily checked, and more accessible for servicing and maintenance than if placed further into the interior to the sewer system.  
         [0011]     These and other features and their advantages will be clear to those skilled in the art of surface water management from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     In the figures,  
         [0013]      FIG. 1A  is an exploded cut-away perspective view of a grated drain with an insert according to a preferred embodiment of the present invention;  
         [0014]      FIG. 1B  is a partially exploded cut-away perspective view of a grated drain with an insert according to a preferred embodiment of the present invention;  
         [0015]      FIG. 2  is an exploded perspective view of an insert according to a preferred embodiment of the present invention;  
         [0016]      FIG. 3  is an exploded cut-away perspective view of a grated drain with an insert according to a preferred embodiment of the present invention;  
         [0017]      FIG. 4  is a top view of a city infrastructure including outflow pipes with inserts according to a preferred embodiment of the present invention;  
         [0018]      FIG. 5A  is a cross-sectional perspective view of an outflow pipe with an insert according to a preferred embodiment of the present invention;  
         [0019]      FIG. 5B  is a cross-sectional side view of an outflow pipe with an insert according to a preferred embodiment of the present invention;  
         [0020]      FIG. 6A  is a cross-sectional perspective view of an outflow pipe having low flow with an insert according to a preferred embodiment of the present invention;  
         [0021]      FIG. 6B  is a cross-sectional perspective view of an outflow pipe having high flow with an insert according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]     The present invention is an insert for use in the inlets or outlets of municipal sewer systems. A municipal sewer system is a network of pipes and conduits that is designed to receive surface water and convey the same to a reservoir, river, or processing station. The inlets to the municipal sewer are typically manholes in streets, and grated drains along curbs and gutters. The outlets are usually large pipes that direct surface water into a body of water such as a lake, a river, or a reservoir.  
         [0023]      FIGS. 1A and 1B  illustrate one embodiment of the present invention, namely an insert  10  for a drain  12  along curbs and gutters. Preferably, insert  10  is dimensioned to be received with little clearance into the specific drain. This dimension allows any surface water running into inlet to flow through insert  10  rather than between it and drain  12 . Insert  10  preferably includes attaching straps  14  and a mesh bag  16  that is preferably made of a loosely woven textile of natural or synthetic fibers and that contains absorber  30 . Drain  12  has a grate  32  with holes that can be used by insert  10  to receive attaching straps  14 . Attaching straps  14  secure and anchor mesh bag  16  to grate  32 . Mesh bag  16  may also be anchored to grate  32  by alternative means of attaching such as carabiners. Preferably, mesh bag  16  includes grommets  18  dimensioned to receive attaching straps  14 . Although  FIGS. 1A and 1B  show that mesh bag  16  is itself attached to grate  32 , an alternative embodiment may include a rigid sleeve into which mesh bag  16  may be contained.  
         [0024]     As shown in  FIG. 1B , attaching straps  14  are threaded through grommets  18  and through the holes of grate  32 , generally acting as a belt to fasten and anchor mesh bag  16  to grate  32 . Grommets  18  are preferably located on the outer edges of absorber  30  so that attaching straps may secure mesh bag  16  in such a way as to minimize its movement during the inflow of water and thereby promote the even distribution of water pollutants throughout absorber  30 . Attaching straps  14  must be sufficiently strong to hold mesh bag  16  in place, even against what might sometimes be a heavy flow of water. Therefore, attaching straps  14  are ideally made of metal such as stainless steel or galvanized steel or of a rigid plastic such as an engineering grade nylon.  
         [0025]     The contents of mesh bag  16  are shown in detail in  FIG. 2 . As illustrated, mesh bag  16  is preferably made of layers of absorber  30  that are contained within a cover  7  of mesh fiber. Although absorber materials may vary depending on the particular contaminants that require filtering, absorber  30  is preferably a combination of a water permeable, hydrophobic oil and solvent absorber such as polypropylene, and most preferably, melt-blown polypropylene and activated carbon. Depending on the types of solvents present in the surface water, the combination of activated carbon and polypropylene may be required to more effectively filter out the pollutants. Although the polypropylene sheets effectively remove oil wastes and hydrocarbons, the activated carbon is more effective at filtering more polar wastes such as acetone. The activated carbon helps to filter a variety of organic solvents, including compounds, such as acetone, that are more polar than oils and hydrocarbons. Preferably, alternating layers of melt blown polypropylene  3  and activated carbon  5  are contained within mesh cover  7  to form mesh bag  16 . As shown, activated carbon  5 , which is typically in powder form, is most preferably contained within additional layers of material, such as melt blown polypropylene, that have been sewn together. This arrangement of layers of absorber  30  is a feature of the present invention. By varying the layers of absorber  30 , contaminants of distinct and varying properties are more effectively filtered. For example, if the water run off includes a mixture of hydrocarbons and more polar solvents, the polar solvents may carry a portion of the hydrocarbons through the top polypropylene layers. However, by providing a layer of activated carbon beneath the polypropylene layer, the polar solvents may be filtered. Further, if the hydrocarbons that were carried by the polar solvents are not filtered at this point and continue through the activated carbon layer, the polypropylene layer beneath the activated carbon layer will filter the remaining hydrocarbons.  
         [0026]     Mesh bag  16  may alternatively just be made of layers of melt blown polypropylene  3 . In areas having mainly concentrations of oils and hydrocarbons, such as drains near gas stations, melt blown polypropylene may be all that is required to effectively filter the water run off.  
         [0027]     Absorber  30  may alternatively be made of a combination of two or more of the following: melt-blown polypropylene, activated carbon, universal polypropylene, which is polypropylene having a surfactant sheen, and polystyrene plastic. Each of these materials contributes to both the buoyancy and filtering capacity of mesh bag  16 .  
         [0028]     As stated previously, a particular feature of the present invention is the use of absorber  30  that can be cleaned and reused, and the solvent and oil recovered. Melt blown polypropylene can be cleaned to remove solvents and oils and then reused without significant degradation. Further, the melt blown polypropylene will retain its buoyancy. Ideally, the holders for absorber  30 , such as mesh bag  16 , can also be reused many times even if absorber  30  is replaced periodically. When absorber  30  is cleaned, the oils and solvents may be recovered for recycle or proper disposal.  
         [0029]     Depending on the location of drain  12 , adjustments may be made to the amount of absorber  30  contained in mesh bag  16 , or to the size of mesh bag  16 . If drain  12  is located near sources of solvents and oils, mesh bag  16  will require larger amount of absorber. If drain  12  is also located where surface water volume peaks are relatively high, mesh bag  16  needs to be larger so that the quantity of absorber  30  is not so dense as to impede water draining and cause drain  12  to back up.  
         [0030]     Also shown in  FIGS. 1A and 1B , is a leaf trap  34  for trapping large particles such as twigs and leaves that is removably attached to the top of grate  32 . Leaf trap  34  preferably includes a coarse mesh grid  38  that is dimensioned to cover grate  32  and to catch and hold leaves and twigs but allow water to pass readily. Leaf trap  34  further includes pliable strips  40  that extend out beyond mesh grid  38  and that can be used to grip leaf trap  34  to outer edges of grate  32 . In servicing insert  10 , leaf trap  34  would be cleaned frequently, such as every few weeks or more often in fall and after heavy downpours.  
         [0031]      FIG. 3  illustrates an alternative embodiment of the present invention, which is also an insert  10  that fits into a drain  12 . Insert  10  includes plural baffles  44  containing absorber  30  and attaching braces  46  that secure plural baffles  44  to inner wall  48  of drain  12 . Below grate  32  of drain  12 , plural baffles  44  are set at angles so as to direct surface water that does not flow through one baffle  44  to the next baffle  44 . Each baffle  44  is shaped to fit drain  12 . Each baffle  44  is mounted so that it is cantilevered from  48  of drain  12  and is sloped downward toward the top of the next baffle  44 . Baffles  44  are made of a loosely woven textile of natural or synthetic fibers and filled with absorber  16 . As shown, braces  46  of baffles  44  are preferably welded or bolted to wall  48  of drain  12  so that baffles  44  are held firmly in place. Alternatively, baffles  44  may be secured to a rigid insert sleeve that may itself be bolted or welded to wall  48  of drain  12 . Structural support in the form of bracing as appropriate for the load can be supplied. Baffles  44  may be one inch to ten inches thick, but three inches is preferred.  
         [0032]     Preferably, insert  10  also includes a leaf trap  34  that is removably attached to the top of drain grate  32 . Similar to leaf trap  34  shown in  FIGS. 1A and 1B , leaf trap  34  of  FIG. 2  includes a coarse mesh grid  38  dimensioned to fit over grate  32  and to catch and hold leaves and twigs but allow water to pass readily. Preferably, mesh grid  38  includes pliable strips  40  that extend out beyond mesh grid  38  that can be used to grip leaf trap  34  to outer edges of grate  32 .  
         [0033]     An alternative embodiment of the present invention is shown in  FIGS. 4-5B .  FIG. 4  shows insert  10  of  FIGS. 5A and 5B  in use within a typical city infrastructure. As shown, insert  10  may be strategically placed along pipes  50  so as to maximize their effectiveness to control and abate pollution. For example, inserts  10  may be placed along pipes in close proximity to gas stations  60  to more effectively reduce the amounts of petroleum and oil that may be concentrated in these areas. Furthermore, inserts  10  may be placed at pipe junctures  62  which will more than likely contain higher concentrations of pollutants. Inserts  10  may also be placed near the pipe opening into a river, a lake or a reservoir. Preferably, insert  10  is placed near an inlet  70  to a pipe system, such as a manhole, to allow for convenient maintenance of insert  10 . Insert  10  is dimensioned to fit within pipe  50  and may be secured to pipe  50  using means for holding  56  such as hooks embedded in wall  58  of pipe  50 . Depending on the size of pipes  50 , size of insert  10  and the container for absorber  30  used may be adjusted accordingly.  
         [0034]     As illustrated, insert  10  includes a frame  100  surrounding and holding mesh bags  16  containing absorber  30 . Mesh bags  16  are divided into multiple chambers  104  formed by coarse mesh screens  54 . As shown, insert  10  holds mesh bags  16  in place by flanges  102  that are located on mesh screens  54 . Flanges  102  are made of a flexible material such as rubber that will bend to allow mesh bags  16  of varying sizes to be inserted and held in place. Mesh bags  16  may be both inserted and released from frame using rod-like tools having means for gripping bags, such as hooks. Chambers  104  of frame  100  of insert  10  are tiered so that each mesh bag  16  sits above or below the neighboring mesh bag  16 . This tiered configuration is preferable because mesh bags  16  can be placed at optimal elevations depending on the water level. For example, in  FIG. 4A , the water level is high; therefore, the most effective placement of mesh bag  16  would be in elevated chamber  104 . However, if the water level were low, as in  FIG. 4B , the most effective placement of mesh bag  16  would be in a lower chamber  104 .  
         [0035]      FIGS. 6A and 6B  illustrate yet another embodiment of insert  10  according to the present invention. In an inlet to a sewer system, namely, a manhole  70  that is located above a pipe  50  from which surface water that has been collected is permitted to enter a river, a lake or a reservoir, is fitted with insert  10  that is dimensioned to fit inside pipe  50  and is attached to the interior walls of manhole  70  by a means for attaching  106 , such as a hook. As shown, insert  10  resembles a pendulum, wherein insert  10  is suspended from a fixed support and swings freely back and forth under the influence of gravity and the flow of the surface water. Preferably, insert  10  is suspended from multiple supports  74  along the interior wall of manhole  70  by means for suspending  108  such as a cable. Preferably, suspending means  108  anchors insert  10  to the interior wall of manhole. Insert  10  is removably attached to supports  74  means for attaching, such as hooks; therefore, insert  10  may be replaced if insert  10  becomes saturated with pollutants.  
         [0036]     Typically, the pollutants in the surface water are concentrated near the top of the water level. Ideally, insert  10  remains on or near the top of the water level as the flow rate of the surface water increases or decreases so as to most effectively filter the surface water pollutants. As shown in  FIG. 6B , insert  10  swings in the direction of the surface water flow and rests on the top of the water level. Regardless of how high the water level becomes, insert  10  will continue to swing in the direction of the water flow and rest on the top of the water where most of the pollutants are concentrated.  
         [0037]     Preferably, insert  10  is made of sheets of melt-blown polypropylene that have been bound together. In order to optimize the filtering of pollutants present in the surface water, insert  10  should be of a weight that allows insert  10  to freely swing and rest on or near the top of the water level. Along the bottom edge of insert  10  may also be included a tear resistant material, such as a hard plastic, that prevents the melt blown polypropylene from becoming tethered as it swings back and forth along the interior walls of pipe  50  below manhole  70 . Although the exact number and dimension of sheets required to serve as a pendulum filter within a sewer system may require experimentation by those skilled in the art, ideally, 3-5 sheets are bound together. Further, these sheets are dimensioned so as to just fit within the bottom of pipe  50 .  
         [0038]     Alternatively, insert  10  is a combination of melt-blown polypropylene and activated carbon. Depending on the types of solvents present in the surface water, the combination of activated carbon and polypropylene may be required to more effectively filter out the pollutants. Specifically, the activated carbon would be contained between bound sheets of polypropylene.  
         [0039]     A preferred embodiment of the present invention was tested on a sample mixture. The sample was made of 32 ounces of liquid. Specifically, the sample included 24 ounces of water and 8 ounces of motor oil, which corresponds to a 3:1 ratio of water to oil. In the test, mesh bag  16  containing absorber  30  was placed beneath sample and over a catch basin. Thereafter, the sample was filtered through mesh bag  16  by pouring it onto mesh bag  16  and into the catch basin. The filtered mixture was then analyzed by a gas chromatograph for the presence of oil and water. The filtered mixture contained 99.9975% water and 0.0025% oil. This result shows the effectiveness of melt blown polypropylene to filter oil from oil and water mixtures.  
         [0040]     Finally, Those skilled in surface water management will recognize that many substitutions and modifications can be made in the foregoing preferred embodiments without departing from the spirit and scope of the present invention.