Abstract:
An apparatus for treating air from an exhaust port of a building. The apparatus includes an enclosed pathway having an inlet for communication with an exhaust port, a discharge outlet, and a non-linear pathway portion between the inlet and discharge outlet. The non-linear pathway includes air treatment material positioned in communication with a portion of the pathway to expose the air to the air treatment material as it moves through the pathway. The apparatus includes an irrigation system for maintaining the moisture content of the air treatment material.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to the field of odor control in agricultural applications. More particularly, the invention relates to structures for reducing or controlling emissions of odorous gases from agricultural buildings or other similar structures.  
       BACKGROUND OF THE INVENTION  
       [0002]     Unwanted by-products of producing livestock include the inherent odors, particularly those created by livestock waste. Livestock waste emits foul and noxious gases, including hydrogen sulfide and ammonia. Not only are these gases unpleasant and potentially dangerous for those who are located near waste collection areas, but many regulatory bodies regulate the permitted emissions of certain gases from an agricultural operation. Further, some regulatory bodies require larger agricultural operations to provide air emission plans, which include methods and practices that will be employed by the agricultural operations to minimize emissions of certain gases and procedures to respond to complaints directed at the facility, including identifying strategies to address the sources of odors and noxious gases. Compounding the problem is that agricultural businesses are often subjected to difficult market conditions, requiring that the livestock producer hold down costs.  
         [0003]     Various strategies can be employed to reduce emissions. One alternative, described in U.S. patent application Ser. No. 11/155,669, incorporated herein by reference in its entirety, is to suppress or neutralize odors within a manure pit of an agricultural building. While this alternative works to suppress odors beneath the building, the odorous gases may also still need to be evacuated at some point in the future.  
         [0004]     Another approach is to attempt to filter gases from exhaust air after it has been evacuated from the building. One known approach is to employ so-called biofilter materials as a filtration media. Biofiltration employs microorganisms present within biodegradable materials to break down gaseous contaminants and reduce the amount of hydrogen sulfide and ammonia present in exhaust air. Prior approaches port exhaust air from an agricultural building into an air plenum located below a field of biofilter material. As the exhaust air is forced into the plenum, the resulting pressure forces the air through the field. However, forcing air through a thick field of biofilter material creates head loss on the exhaust fan, resulting in a need for more a powerful exhaust fan. Further, a number of other factors, including the particular choice of biofilter material and the settling of biofilter material over time can exacerbate the head loss. In addition, a phenomenon known as channeling, which is the shifting of material across the field, can create localized areas within the field with reduced humidity as more air passes through areas with a smaller concentration of material. Reduced humidity can result in reduced microorganism activity, which unfortunately reduces the filtering capability of the field. In addition, it is recommended that biofilter fields be located on sloping, well-drained land to control the amount of moisture the field of biofilter material, thereby limiting where biofilter fields can be employed.  
         [0005]     What is needed then, is an effective way to reduce the emission levels of odorous and noxious gases of exhaust air from agricultural applications, such as the exhaust air from agricultural livestock buildings. The solution should result in minimal head loss on the exhaust fan, be easily maintained, employable in a large number of applications, and should be relatively inexpensive.  
       SUMMARY OF THE INVENTION  
       [0006]     One embodiment of the invention is an apparatus for treating air from an exhaust port of a building. The apparatus includes an enclosed pathway for connection to the exhaust port of the building and a non-linear pathway extending from the inlet to a discharge outlet. The apparatus further includes air treatment material positioned along at least a portion of the pathway so that air is exposed to the air treatment material as it moves through the pathway. Yet another embodiment of the invention includes an irrigation system for increasing the moisture content of the air treatment material. The irrigation system can include an inlet to be connected to a moisture source and at least one moisture distribution member such as a sprinkler for irrigating the air treatment material. The irrigation system further includes a flow control member that controls the flow of moisture from the moisture source to the at least one moisture distribution member. The irrigation system also includes a moisture sensing device positioned within the pathway. The moisture sensing device is coupled to a controller, which is also coupled to the flow control member to controlling the flow of moisture to the air treatment material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is an isometric illustration of an agricultural building having an exhaust fan outlet coupled to an exhaust treatment member in accordance with one embodiment of the invention.  
         [0008]      FIG. 2  is a front view of the agricultural building of  FIG. 1 , illustrating the coupling of the agricultural building to the exhaust treatment member.  
         [0009]      FIG. 3  is a cross sectional view through the exhaust treatment member along lines  3 - 3  in  FIG. 1 .  
         [0010]      FIG. 4  is a cross sectional view through the exhaust treatment member along lines  4 - 4  in  FIG. 2 .  
         [0011]      FIG. 5  is a schematic illustration of the air flow through the exhaust treatment member of  FIG. 1 .  
         [0012]      FIG. 6  is an exploded view or illustration of a tray for carrying air treatment material shown in  FIGS. 3-4 .  
         [0013]      FIG. 7  is a schematic illustration of an irrigation system for the exhaust treatment member of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]      FIGS. 1 and 2  illustrate an agricultural building  6  that is coupled to an exhaust treatment member  10  in accordance with one embodiment of the invention. The agricultural building  6  is coupled to the exhaust treatment member  10  on the output side of an exhaust fan (not shown) that is positioned to draw air out of the agricultural building. The exhaust fan is positioned near a manure pit (not shown) to evacuate air in the manure pit area, although the exhaust fan may be located anywhere as long as it can draw air out of the agricultural building  6 . The agricultural building  6  is coupled to a treatment member inlet  14  on the exhaust treatment member  10  through a duct  12 . Duct  12  has an interior cross section that is approximately the same or larger than an output port (not shown) on the output side of the exhaust fan at the location where output port is coupled to the duct  12 . The interior cross sectional area of duct  12  is generally constant or increasing from the output port to the treatment member inlet  14 . Exhaust air from the barn  6  is thus forced through the exhaust output port and into the exhaust treatment member  10  through the treatment member inlet  14  to accommodate the air flow from the exhaust fan without creating a load on the exhaust fan. In addition, the duct  12  is shaped to mate with the treatment member inlet  14 , which may have a different general shape than the exhaust port on the agricultural building  6 . For example, the output port (not shown), in one embodiment, has a circular shape and the treatment member inlet  14  has a generally rectangular shape.  
         [0015]     Referring to  FIGS. 3, 4 , and  5 , the exhaust treatment member  10 , in one embodiment, is a generally rectangularly shaped structure with a generally hollow interior. The exhaust treatment member  10  includes a frame  20  and outer surfaces  22  attached to the frame  20 . The frame  20  and outer surfaces  22  of exhaust treatment member  10  can be made of a number of known materials. For example, the frame and outer surfaces can be made of wood, metal, plastic, foam, or other suitable materials. The outer surfaces  22  preferably have some insulative properties to maintain warmth and, correspondingly, increased microorganism activity within the exhaust treatment member  10  during cold weather.  
         [0016]     The interior of exhaust treatment member  10  includes a plurality of trays  30 , adapted to hold an air treatment material  40 , that are arranged within the exhaust treatment member  10 . As illustrated in  FIG. 3 , the trays  30  have a width that is approximately the same as that of the exhaust treatment member  10 . However, as illustrated in  FIG. 4 , the trays  30 , have a length that is less than that of the exhaust treatment member  10 . Further, the trays  30  are arranged within the housing so that the trays are alternately adjacent to a first side  24  and a second side  26 , thereby creating a serpentine pathway  18 , as shown in  FIG. 5 , for incoming air to make several turns as it moves through a plurality of segments A-E in the exhaust treatment member  10  from the treatment member inlet  14  to a discharge outlet  16 . As the exhaust air moves through the pathway  18 , it passes by each of the plurality of trays  30  with air treatment material  40 . In one embodiment, five trays  30  are aligned within the exhaust treatment member  10 , although any number of trays may be used as necessary. The trays  30  are arranged and sized within the exhaust treatment member  10  to define the pathway  18  with sufficient cross-sectional area to allow air to flow through exhaust treatment member  10  and interact with air treatment material  40  while creating minimal head loss on the exhaust fan.  
         [0017]     A top surface  28 , in the illustrated embodiment, is formed by a tray  30 . Alternatively, a roof structure (not shown) is attached to the exhaust treatment member  10  to extend above the tray on the top surface  28  of the exhaust treatment member. Alternatively, the roof extends above the entire top surface  28  and the discharge outlet  16  is channeled out of the exhaust treatment member  10  beneath the roof. Alternatively still, the tray  30  that forms the top surface  28  may extend across the entire top surface, including the exhaust port (not shown). As the exhaust air passes through the serpentine pathway  18  it will gradually decrease in velocity even as it interacts with the material in the trays  30 . In addition the final tray has a relatively small amount of treatment material located within it, so that the exhaust air can pass through it with minimal head loss on the fan.  
         [0018]     Referring to  FIG. 6 , the trays  30 , in the illustrated embodiment, have a frame  32  that defines the length and width of the tray. The frame  32  is attached to the frame  20  of the exhaust treatment member  10  (as shown in  FIGS. 3 and 4 ). Frame  32  can be formed from metal, wood, plastic, or any other suitable material. A support structure  34  is positioned within and attached to frame  32 . Support structure  34  includes a plurality of segments  35  that extend across the length and width of the tray. The segments  35 , in the illustrated embodiment, are formed from wire and attached to each other at the intersection points to form a mesh-type structure. Alternatively, the support structure  34  is formed from wood, plastic, or other suitable materials. Alternatively still, the segments  35  are not connected to each other, but to the frame  32  of the tray  30 .  
         [0019]     Liner material  37 , is a porous material, such as geotextile material, which is placed onto the support structure  34 . A layer of air treatment material  40  is then placed onto the trays  30 . In one embodiment, the air treatment material  40  is a mixture of biodegradable materials, such as compost and wood chips, although other similar materials may be used. Although shown as a collective mass in  FIG. 6 , it should be understood that air treatment material  40  can be freely and loosely distributed within the trays  30 . The liner material  37  supports the layer of air treatment material  40  and is porous enough to allow moisture to flow through the liner material, but also supports the layer of air treatment material. Importantly, the liner material  37  allows the microorganisms active in the air treatment material to migrate through the liner material and position themselves on an opposing side of the liner material from the air treatment material  40 . Thus, referring again to  FIG. 5 , as air passes through the pathway  18  of exhaust treatment member  10 , more of the air is subjected to interaction with the microorganisms to reduce the concentration of unwanted gases, including hydrogen sulfide and ammonia. For example, as exhaust air travels through segment A microorganisms from the tray  30  located directly above segment A interact with the exhaust air. Similarly, as exhaust air moves through segment B, microorganisms from the trays  30  above and below segment B likewise interact with the exhaust air.  
         [0020]     Alternatively, the trays  30  can have a number of different forms without departing from the scope of the invention. For example, the trays  30  can be formed from a five sided box (not shown) having a plurality of apertures formed into a bottom surface of the box and a liner material positioned with the box. Liner material of the type described above may be positioned within the five-sided box to hold the air treatment material, if necessary. As another example, the trays  30  can have a frame to define the length and width with liner material attached to the frame to define a bottom of the tray (not shown). Further, while the illustrated embodiment depicts trays  30  that are attached to the frame  20  of the exhaust treatment member (as shown in  FIGS. 3 and 4 ), alternatively the trays  30  are removably positioned within the exhaust treatment member  10  to allow for maintenance and replacement of the biodegradable material. For example, the trays  30  may be slidably removable from the exhaust treatment member  10 .  
         [0021]     In the illustrated embodiment, the exhaust treatment member  10  is eight feet wide and eight feet in length. The trays  30  have a width of eight feet and a length of six feet, thereby leaving a two feet by eight feet pathway at the end of each tray for air to reverse course. The exhaust treatment member  10  has a height of eight feet with five trays  30  generally evenly spaced within the exhaust treatment member. These measurements are given for illustrative purposes only. The exhaust treatment member  10  and trays  30  may be sized to properly treat the exhaust air depending upon the output capabilities of the exhaust fan. Thus, the exhaust treatment member  10  and trays  30  may be sized differently without departing from the scope of the invention. As an example, in an alternative embodiment (not shown), to accommodate an exhaust fan with increased flow, the exhaust treatment member  10  has a larger number of trays  30  and therefore the height of the exhaust treatment member is increased. In another alternative embodiment, exhaust treatment member  10  has an extended length, and the corresponding trays  30  are similarly lengthened within the exhaust treatment member. It has been found that increasing the length of trays and, by extension, the overall length of the exhaust treatment member  10  is an effective way to improve the air treatment capabilities of the exhaust treatment member. In still another embodiment, an exhaust fan with smaller total air flow could use a smaller exhaust treatment member  10 , including a smaller width and/or length and correspondingly smaller trays  30  or a reduced number of trays and a correspondingly reduced height.  
         [0022]     Referring to  FIGS. 3, 4 , and  7 , exhaust treatment member  10  includes an irrigation system  50  for measuring the moisture level of the biodegradable material  40  and providing moisture to the biodegradable material to maintain the moisture within a desired moisture level to maintain acceptable microorganism activity. Irrigation system  50  includes an inlet  52  for connection to a moisture source  51 . In one embodiment, the moisture source is a pressurized water source  51 . Alternatively, the moisture source  51  can be an unpressurized water source. Alternatively still, the moisture source  51  can include substances other than water. For example, chemicals may be added to the moisture source  51  to treat the biodegradable material.  
         [0023]     Moisture is transmitted from the moisture source  51  to a flow control member  54  through a conduit  56 . Flow control member  54  controls the flow of moisture through the irrigation system, including blocking flow, if necessary. In one embodiment, the flow control member is a valve. More particularly, flow control member, in one embodiment, is a solenoid valve. The valve can be an on/off valve or alternatively, it can be a metering valve for controlling the amount of flow within the moisture system. Alternatively, the flow control member  54  is a pump for drawing moisture from an unpressurized moisture source  51 . Conduit  56  can be pipes or hoses suitable for transporting water in the irrigation system  50 .  
         [0024]     The irrigation system  50  also includes, in one embodiment, a plurality of moisture distribution members  58  positioned in proximity to the plurality of trays  30  within the exhaust treatment member  10  to distribute moisture to the biodegradable material  40 . In the illustrated embodiment, the moisture distribution member  58  is a sprinkler head positioned above the tray  30 , although other types and arrangements of moisture distribution members may be used. In the illustrated embodiment, two moisture distribution members  58  are positioned over each of the plurality of trays  30 . The number of moisture distribution members  58  may vary depending on the size of the trays and the amount of area to which each of the moisture distribution members can provide moisture. Each of the moisture distribution members  58  is attached to the flow control member  54  through a plurality of conduits  56 .  
         [0025]     The irrigation system  50  also includes a moisture sensor  60  positioned within the exhaust treatment member  10  to sense the moisture level of the biodegradable material  40 . In one embodiment, the sensor  60  is positioned within one of the trays  30  that define a portion of segment B of pathway  18  (shown in  FIG. 5 ). Alternatively, the moisture sensor  60  can be positioned anywhere within the exhaust treatment member  10 . Alternatively still, the irrigation system  50  can include a plurality of moisture sensors  60  positioned within the exhaust treatment member  10 .  
         [0026]     The moisture sensor  60 , in one embodiment, is connected to a controller  62 , which is adapted to interact with the moisture sensor to determine the moisture content of the air treatment material  40 . The controller  62  is, in one embodiment, an electronic controller that receives an electric signal from the moisture sensor  60 . Controller  62  can be any type of known electronic controller, including a programmable logic controller, a programmable logic array, or similar types of controllers or electronic devices. Controller  62  sends an electrical signal to flow control member  54  to activate the flow control member to supply moisture through the plurality of conduits  56  to the moisture distribution members  58 .  
         [0027]     The current invention provides a number of advantages. Exhaust air is treated without incurring significant head loss on the exhaust fan. The current invention reduces the problems associated with traditional biofilter fields, including a need for a sloped area and a relatively large amount of land for the biofilter field. In addition, the enclosed structure reduces the effects of channeling of biodegradable material. The irrigation system provides an effective way to keep the biodegradable material within a desired range of moisture content to improve the performance of the microorganisms. In addition, such a system is easily adapted to existing structures.  
         [0028]     Those skilled in the art will appreciate that modifications can be made to the illustrative embodiments without departing from the scope of the invention.