Abstract:
A system for deodorizing malodorous sewer gas having a tower with a lower gas inlet and an upper gas outlet, malodorous gas passing into the tower through the gas inlet. Packing is positioned within the tower between the inlet and outlet. An enzyme solution recirculating system withdraws enzyme solution from the interior bottom of the tower and introduces it into an upper portion of said tower, the enzyme solution passing downward through the packing. A blower moves malodorous gas into the tower inlet and upwardly through the packing for contacting downwardly passing enzyme solution. An enzyme solution replenishment system is connected to the circulation system.

Description:
This application is a conversion application related to U.S. Provisional application Ser. No. 60/132,838, filed May 6, 1999. 
    
    
     SUMMARY OF THE INVENTION 
     Any closed system for handling sewage is a potential source of odor pollution. Lift stations and pump stations where sewage is moved in a sewage treatment process are frequent sources of odor. Decomposition of sewage frequently results in production of hydrogen sulfide and other malodorous gases. 
     This invention provides a system and a method of treating gases that emanate from lift stations, pump stations and other similar sewage handling facilities so as to eliminate objectionable odor passing into the atmosphere. 
     The system herein consists essentially of passing malodorous gases generated by sewage systems upwardly through a vertical tower, the gases being contacted by a downwardly flowing enzyme solution followed by ozone neutralization. The enzyme solution is obtained by natural fermentation of food grade materials, selected strains of bacteria from which a substantially pH neutral enzyme soup is obtained that is blended with micro-nutrients and biocatalysts. The enzyme solution is cascaded downwardly through filler materials, preferably jaeger tripac ceramic skeletal spheres or PVC biochips. The filler material provides high surface areas per unit volume allowing substantial gas contact with surfaces wetted by the enzyme solution. 
     Enzyme solution collected in the bottom of the tower is recirculated by a pump for continuous discharge into the top of the tower. Fresh enzyme solution is continually added by means of a venturi connected to a timed solenoid valve. The venturi withdraws fresh enzyme solution from a reserve tank. 
     Positioned above the packing material in the upper portion of the tower is an ozone contact chamber. Ozone produced by an ozone generator is continuously conveyed into the ozone contact chamber, the noxious gases, after being contacted by the enzyme solution, are contacted by ozone within the upper portion of the tower and mixed with the noxious gases that remain before they are discharged to the atmosphere. The resultant discharge gases are substantially free of odor. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic elevational view of the system for practicing the method of this invention showing a tower and associated equipment by which sewer gas is contacted with an enzyme solution and ozone. 
     FIG. 2 is another cross-sectional elevational view essentially taken 90° from that of FIG. 1, the contact tower and associated equipment. 
     FIG. 3 is an enlarged elevational view of a segment of FIG. 2 showing more details of the system by which enzyme solution is introduced into the tower and excess solution withdrawn from the bottom of the tower. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawing, the main element of the system is a vertical tower  10  that can be made of metal, fiberglass or plastic. Tower  10  can be made from schedule  80  PVC pipe. While the diameter and height of the tower can vary according to the volume of sewer gas being treated, for the typical lift or pump station a tower that is 12 inches in diameter and a height of about 76 inches functions satisfactorily. The tower has a closed top  12  and a closed bottom  14 . The bottom can rest on a surface or on top of a typical lift or pump station that is usually formed of concrete. 
     The typical lift station or pump station with which the system is employed has an opening  16  from which gas can be withdrawn. The withdrawn gas flows through a conduit  18  and through an inlet opening  20  into the interior of tower  10 . Within the tower and positioned above opening  20  is a horizontal perforated support plate  22 . Stacked on top of support plate  22  is packing  24 . The function of packing  24  is to provide a large amount of surface area in an irregular pattern past which gases can upwardly move in the tower. A commercially available type of packing that functions ideally for this application is called “Jaeger balls”. This product is of spherical skeletal configuration, usually made of ceramic or other non-metallic material, and has a very high surface area to unit volume ratio. Another commercially available product, made of PVC plastic, is sold under the trademark “Bio-chips”; both of those products are designed to achieve enhanced contact between the downward passing solution and upward flowing sewer gas. 
     Packing  24  is stacked within the tower  10  above a perforated support plate  22  to a height that is below the tower top  12 . 
     Sewer gas is drawn into the tower through opening  20  by means of a blower  26  operated by a motor  28 . A gas outlet opening  30  in the top of the tower, immediately below top  12 , has connected to it a downwardly extending tower contact pipe  32  that connects to an inlet  34  of blower  26 . The outlet  36  of blower  26  connects with an exhaust pipe  38  that vertically extends upwardly to a selected height, usually above the top  12  of the tower. At the top of exhaust pipe  38  a tee fitting  40  is positioned. The tee fitting is open at both ends to permit free discharge of gases from pipe  38  to the atmosphere but to prevent rainwater from entering into the pipe. 
     The air flow system as described produces a path that moves air upwardly within tower  10 , through packing  24  and through an upper end portion of the interior of the tower. 
     In order to abate the odors of the sewer gas, this invention employs a unique combination of enzyme solution and ozone. When the system is first placed in operation a fill cap  42  (see FIGS. 2 and 3) is removed from a fill/overflow apparatus  44 . A drain valve  46  below apparatus  44  is closed and with fill cap  42  removed, enzyme solution is added to flow through a pipe  48  extending through the wall of tower  10 . Sufficient enzyme solution is added to reach a level  50  that is below support plate  22 . After level  50  is reached, fill cap  42  is replaced and drain valve  46  is open. A vertical extension  48 A of pipe  48  drains excess enzyme solution out of tower  10  from adjacent the tank bottom  14 . Enzyme solution useful in the system of this invention is commercially available from Enzymatic Odor Solutions, Inc. a Florida corporation located at 1811 Bayberry Drive, Pembroke Pines, Fla. 33027 under the trademark, “AVAST 660+”. 
     An enzyme circulating pump  52  has an inlet connected by pipe  54  to an opening  56  in tower  10 , opening  56  being adjacent to and above tower bottom  14 . Pump  52 , powered by a motor  58 , draws enzyme solution from the lower portion of the tower and conveys it, by vertical conduit  60  to inlet opening  62  in the upper portion of the tower. Within the interior of the tower, in the top portion thereof, a horizontal pipe  64  extending through opening  62  terminates in a spray nozzle  66 . Enzyme solution is recirculated from the lower portion of the tower, through pump  52 , vertical conduit  60 , horizontal conduit  64  and spray nozzle  66  to be injected into the interior of the tower and to pass downwardly through packing  24 . As the enzyme migrates downwardly it thoroughly contacts the surfaces of the packing, causing wetted surfaces that are contacted by the upwardly flowing sewer gas. 
     Enzyme solutions are commercially available and are typically obtained from natural fermentation of food grade materials by the use of multiple strains of bacteria to obtain a concentrated enzyme soup. This concentrated enzyme soup is employed in a mixture including micro-nutrients and biocatalyst to provide a solution that biodegrades odor produced as components of sewer gas. While commercially available odor abating enzyme solutions are available that can be used in the invention, proprietary enzyme solutions may also be used. 
     It is important that fresh enzyme solution be supplied to the system and for this purpose a venturi  68  is installed in conduit  60  through which the recirculated enzyme solution flows. Venturi  68  functions in a customary manner to derive from the flowing liquid stream a vacuum that is coupled by a conduit or hose  70  to the outlet  72  of a solenoid valve  74 . Connected to the inlet  76  of the solenoid valve is a conduit  70  extending from a reservoir  81  which is kept supplied with fresh enzyme solution. Solenoid valve  74  is controlled between open and closed positions by a timer  80 , the timer and solenoid valve being connected by a conductor  78 . When valve  74  is open the vacuum obtained from venturi  68  is applied through conduit  70  to withdraw fresh enzyme solution from reservoir  81 . The fresh enzyme solution is passed into the recirculated enzyme solution flowing through conduit  60 . By regulating the open/closed time relationship supplied by timer  80 , the quantity of fresh enzyme solution continually added to the recirculated enzyme solution can be controlled. Typically, timer  80  may close solenoid valve  74  for  240  seconds, then open the valve for 10 seconds, and constantly repeat this cycle. If more fresh enzyme solution is required the operator can adjust timer  80  to increase the percentage of time that solenoid valve  74  is open. 
     As enzyme accumulates within the lower portion of tower  10  it is automatically discharged through fill/overflow apparatus  44  and drain valve  46  to flow by a conduit or hose  84  for discharge, such as back into the sewer system. 
     Positioned within the upper portion of tower  10  is a demisting plate  86  that serves to extract any excess fluid, such as enzyme solution, from the upwardly passing gas before the gas is discharged through outlet opening  30 . To further treat odor contaminants within the gas an ozone contact chamber  88  is maintained in the upper portion of the tower  10 . Ozone gas is created by an ozone generator  90  located adjacent to the tower  10 . Ambient air drawn in by compressor  94  passes through an air preparation unit  92 . Compressed air from air compressor  94  passes through conduit  96  into and through the air preparation unit  92 , then to the ozone generator  90  by conduit  97 , then through conduit  98  through an opening  100  into an ozone dispensing nozzle  102  located within the tower then into the ozone contact chamber  88  located in tower  10  above the demisting plate  86  and within the ozone contact chamber  88 . 
     Sewer gas passing upwardly in the tower through packing  24  contacts enzyme solution wherein biological reaction serves to neutralize malodorous components including hydrogen sulfide. Hydrogen sulfide and other non biological components of the sewer gas are further neutralized by ozone within ozone chamber  88 . Sewer gases and ozone are thoroughly mixed as they pass downwardly through tower contact pipe  32 . The enzyme solution is preferably formulated to be substantially neutral, that is having a pH of about 7 to 8 so, that it is neither substantially acidic or basic and therefore as acceptable for release to the atmosphere. The ozone helps to ensure that any living organisms that might be moved by the sewer gas are killed so that live bacteria is not discharged from the system to the atmosphere. 
     Tower  10  is a non-pressurized vessel. Under optimum operating conditions gas discharged from the system is non-toxic, noncorrosive, noncombustible and substantially odor free. To test for effectiveness of the system, measurements for gas odor should be taken one to two feet from exit  40 . 
     As the solution passes downwardly through packing  24  it creates a liquid film. As this film builds up the biodegradation of odors of upwardly passing gases improves. Further the resultant film results in the creation of massive colonies of arobic bacteria that further enhances the effectiveness of the system. 
     The claims and the specification describe the invention presented and the terms that are employed in the claims draw their meaning from the use of such terms in the specification. The same terms employed in the prior art may be broader in meaning than specifically employed herein. Whenever there is a question between the broader definition of such terms used in the prior art and the more specific use of the terms herein, the more specific meaning is meant. 
     While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.