Abstract:
The present invention is a self-regenerating biofilter. The biofilter tank receives untreated water through an intake inlet, filters it through a filtration mass and expels purified water through an output outlet. The filtration mass includes gravel and activated carbon layers separated by a mesh screen. A compressed air line is located below the mesh screen. Periodically, the biofilter self-cleans by opening a flush valve that expels a flush water stream carrying debris. The biofilter self-regenerates by periodically stopping filtration for a time, allowing biological matter left on the activated carbon to degrade into biomass. Periodically, the biofilter removes and flushes out biomass by application of water or a combination of air and water.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0001]    The invention described herein was made by an employee of the United States Government and may be manufactured and used by the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    This invention relates to the field of liquid purification or separation and more specifically to a particulate material type separator with rehabilitation means. 
         [0004]    2. Description of Related Art 
         [0005]    Aerobic water treatment systems utilize oxygen and microbes to degrade organic matter and neutralize contaminants, allowing reuse of the water. Typically, aerobic treatment is a two-step process. The first phase is physical filtration of larger particles, which aggregate into a separate biomass. Microbes then degrade the remaining organic matter until it is stable and/or less hazardous. 
         [0006]    Fixed-media biological filtration methods rely on either trickling water over media or submerging the media in water. Trickling methods involve continual trickling of water over large filtration media or intermittent trickling of water over large media. Submersion methods rely on continuous operation of a fully submerged filter or other media, which is periodically removed for cleaning or replacement to retain its absorptive capacity. 
         [0007]    Several problems are known in the art with respect to both trickling and submersion methods. First, both methods require substantial down time to change filtration media and/or remove the solid biomass from the system. Both methods also require substantial energy to maintain continuous trickling of water or flow through submerged media. 
         [0008]    There is an unmet need in the art for a biofilter capable of biological regeneration in place (self-cleaning) in a manner that allows it to restore its adsorptive capacity 
         [0009]    There is a further unmet need in the art for a biofilter that can facilitate more efficient control of the temperature at which biological treatment occurs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    In one embodiment of the present invention, a self-regenerating biofilter apparatus includes a biofilter tank, a filtration mass and a compressed air line. The biofilter tank includes an intake inlet connected to a first channel and receiving an untreated water stream. The biofilter tank also includes an output outlet connected to a second channel and expelling a purified water stream. The biofilter tank also includes a flush valve expelling a flush water stream. The filtration mass includes a layer of gravel and a layer of non-gravel materials. The layer of non-gravel material includes activated carbon. The filtration mass is located within the biofilter tank and at least partially above the intake inlet and the flush valve. A mesh screen separates the layer of gravel from the layer of non-gravel material. The compressed air line is located at least partially within the biofilter tank below the mesh screen. 
         [0011]    In another embodiment of the present invention, a self-regenerating biofilter system includes at least one self-regenerating biofilter apparatus, as above, and a central controller connected to the flush valve and connected to a power source. 
         [0012]    In another embodiment of the present invention, a method for using a self-regenerating biofilter apparatus, as above, includes iteratively invoking a function n times. The function includes the steps of: receiving an untreated water stream into a biofilter tank through an intake inlet; filtering the untreated water stream through the filtration mass to transform the untreated water stream into the purified water stream; expelling the purified water stream through the output outlet connected to the second channel; stopping receiving the untreated water stream; opening the flush valve; draining the flush water stream through the flush valve; closing the flush valve and waiting for a predetermined time period before invoking another iteration of the function. The method also includes the steps of receiving the untreated water stream into the biofilter tank through the intake inlet, opening the flush valve, draining the flush water stream through the flush valve and closing the flush valve. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWING(S) 
         [0013]      FIG. 1  illustrates a side view of an exemplary embodiment of a self-regenerating biofilter. 
           [0014]      FIG. 2  illustrates an exemplary embodiment of a self-regenerating biofilter system. 
           [0015]      FIGS. 3 a  and 3 b    illustrate an exemplary embodiment of a method for using a self-regenerating biofilter. 
       
    
    
     TERMS OF ART 
       [0016]    As used herein, the term “channel” means a structure used to convey fluids. 
         [0017]    As used herein, the term “ion exchange media” means media that can exchange ions with a solution of electrolytes. 
         [0018]    As used herein, the term “mesh” means a material having apertures. 
         [0019]    As used herein, the term “mesh size” means the number of apertures per square inch in a mesh through which a particle can pass. The higher number a mesh size has, the smaller a particle must be to pass through the mesh. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIG. 1  illustrates a side view of an exemplary embodiment of a self-regenerating biofilter  100 . Self-regenerating biofilter  100  includes a biofilter tank  10 , a filtration mass  20 , an optional controller  30 , a compressed air line  40 , an optional heating element  50 , and at least one vent  60 . 
         [0021]    Biofilter tank  10  houses filtration mass  20 , compressed air line  40  and heating element  50 . Biofilter tank  10  has a volume ranging from approximately 5 gallons to approximately 5,000 gallons, with a daily flow-through volume ranging from approximately 50 gallons to approximately 50,000 gallons. Intake inlet  11  provides influent of an untreated water stream  14 , while output outlet  12  removes a purified water stream  15 . Intake inlet  11  is located on a level below filtration mass  20  to ensure capture of large particulates below filtration mass  20 . 
         [0022]    Flush valve  13  permits draining of biofilter tank  10  to allow air to enter filtration mass  20  to aid microorganisms in breaking down any biodegradable contaminants adsorbed from untreated water stream  14  and turn them into biomass. In the exemplary embodiment, flush valve  13  is a solenoid valve. In other embodiments, flush valve  13  is a pinch valve, solenoid valve, or ball valve. In various embodiments, operation of flush valve  13  may occur automatically or manually. 
         [0023]    The capture of large particulate occurring on a level below filtration mass  20  permits easily removal of the same large particulates in a flush water stream  16  traveling through flush valve  13 . At least one of biofilter tank  10  and the channels  17   a  and  17   b  connected to intake inlet  11  and output outlet  12 , respectively, includes at least one vent  60  for pressure equalization. Optionally, at least one of intake inlet  11 , output outlet  12 , channel  17   a  or channel  17   b  includes a flow meter sensor  18  to measure flow volume of untreated water stream  14  or purified water stream  15 . 
         [0024]    Filtration mass  20  removes water contaminants by straining, adsorption and/or biological remediation. Biodegradable contaminants in untreated water stream  14  provide food for microorganisms in filtration mass  20  and become biomass. Filtration mass  20  adsorbs these contaminants, which has an impact on filtration mass  20 . 
         [0025]    Filtration mass  20  is made up of separate layers of gravel  21  and non-gravel material. In the exemplary embodiment, non-gravel material is activated carbon  22  and optional ion exchange material  23 . Gravel  21  is crushed rock having an average diameter ranging from approximately 5 mm to approximately 30 mm. Activated carbon  22  is granular activated carbon having a mesh size ranging from approximately 8 to approximately 12.Ion exchange material  23  also has a mesh size ranging from approximately 8 to approximately 12. 
         [0026]    In the exemplary embodiment, ion exchange material  23  is zeolite. In other embodiments, ion exchange material  23  is a synthetic material specifically selected to target a particular contaminant of interest that can be biodegraded or bioaccumulated. By way of non-limiting example, in one embodiment, ion exchange material  23  is a tannin anion resin targeting humic acids and tannins. Certain embodiments may use multiple different ion exchange materials  23  to target multiple contaminants of interest. 
         [0027]    In certain embodiments, at least one of activated carbon  22  and ion exchange material  23  includes a bioculture seed. Bioculture seeds may include custom cultures generated for the particulate contaminant stream of interest by mixing an environmental source (i.e., soil, sludge) with a growth media containing nutrients and the desired target contaminants. Bioculture seeds may include commercial aerobic cultures such as those used for the aquarium industry, or pure cultures of microbes with desired physiological attributes for the desired biodegradation process or environment. 
         [0028]    A mesh screen  24  separates gravel  21  from activated carbon  22  and ion exchange material  23 . In the exemplary embodiment, filtration mass  20  makes up approximately 50% to approximately 85% of the volume of biofilter tank  10 . Gravel  21  makes up approximately 3% to approximately 10% of filtration mass  20 . Activated carbon  22  makes up approximately 60% to approximately 97% of filtration mass  20 . Ion exchange material  23  makes up to approximately 30% of filtration mass  20 . 
         [0029]    In the exemplary embodiment, self-regenerating biofilter  100  includes controller  30 . Controller  30  connects to flush valve  13 , allowing it to control when self-regenerating biofilter  100  drains and regenerates. In the exemplary embodiment, controller  30  includes a timer  31 , a memory  32 , a biomass sensor  33 , at least one power source  34  and a controller interface  35 . Timer  31  allows flush valve  13  to open and close according to a pre-programmed cycle, which may be located in memory  32 . The duty cycle for flush valve  13  may range from approximately 10% to approximately 90%, depending on the contaminant loading rate on a given volume and geometry of filter mass  20  and the adsorptive capacity of filter mass  20  for the contaminant. In the exemplary embodiment, flush valve  13  has an approximately 50% duty cycle, open for approximately four hours and closed for approximately four hours, allowing degradation of biodegradable contaminants on activated carbon  22  and ion exchange material  23 . 
         [0030]    Biomass sensor  33  provides a user or controller  30  with information about the level of biomass in self-regenerating biofilter  100 . This allows automated or manual triggering of a biomass removal cycle when biomass in self-regenerating biofilter  100  has reached a critical level. In one embodiment, biomass sensor  33  senses a head differential across filter mass  20 . In another embodiment, biomass sensor  33  senses UV light absorbance across filter mass  20 . Power source  34  may be a DC or AC voltage source. Power source  34  couples to controller  30  and other parts of self-regenerating biofilter  100  that might require power. In certain embodiments, each part of self-regenerating biofilter  100  that might require power has a separate power source  34 . Controller  30  optionally includes a controller interface  35 , which may permit a user to enter commands to and receive output information from controller  30 . 
         [0031]    Compressed air line  40  is located just below mesh screen  24 . An air source  41 , such as, but not limited to an air compressor or compressed air cylinder, provides an air stream  42  through compressed air line  40 . Controller  30  may connect to air source  41 , allowing controller  30  to control the flow of air through compressed air line  40 . During a biomass removal cycle, air stream  42  travels through compressed air line  40  and enters biofilter tank  10  through at least one air line aperture  43 . Air stream  42  can also enter into filtration mass  20  after draining self-regenerating biofilter  100  to further increase oxygen concentrations. A resistive heater may pre-warm air stream  42  to increase the temperature of filtration mass  20  during regeneration. 
         [0032]    Combined with an influx of untreated water stream  14  from intake inlet  11 , air stream  42  fluidizes and tumbles activated carbon  22  and ion exchange material  23 , removing biomass from activated carbon  22  and ion exchange material  23 . In the exemplary embodiment, biomass removal occurs every two days. This frequency may increase for untreated water streams  14  having high amounts of biodegradable contaminants. The frequency of biomass removal may likewise decrease for untreated water streams  14  having low amounts of biodegradable contaminants. In certain embodiments, use of air stream  42  may not be necessary for untreated water streams  14  having low amounts of biodegradable contaminants. 
         [0033]    In the exemplary embodiment, self-regenerating biofilter  100  includes heating element  50 . Although self-regenerating biofilter  100  does not require heat in many environments, certain biological degradation processes may accelerate due to application of heat creating an optimal temperature for biodegradation rates and biomass production. Heating element  50  is located within biofilter tank  10  and couples to controller  30 . A thermal sensor  51  coupled to controller  30  takes temperature readings to ensure that the temperature does not increase or decrease to undesired levels. 
         [0034]      FIG. 2  illustrates an exemplary embodiment of a self-regenerating biofilter system  200 . Self-regenerating biofilter system  200  includes at least one self-regenerating biofilter  100  and a central controller  210 . Self-regenerating biofilter system  200  is a scalable system. The exemplary embodiment shows a self-regenerating biofilter system  200  with a single self-regenerating biofilter  100  having a volume of 5 gallons, with a daily flow-through volume of approximately 50 gallons. Another embodiment incorporates twelve self-regenerating biofilters  100 , each having a volume of 210 gallons. This self-regenerating biofilter system  200  has a daily flow-through volume of approximately thirty thousand gallons. 
         [0035]    Central controller  210  connects to controller  30  and flush valve  13 , allowing it to both send commands to controller  30  and override controller  30  to open flush valve  13 . Certain embodiments of self-regenerating biofilter system  200  replace controller  30  with central controller  210 . Central controller  210  may also directly connect to any sensors of self-regenerating biofilter  100 , such as, but not limited to, flow meter sensor  18 , biomass sensor  32  or thermal sensor  51 . 
         [0036]    Central controller  210  optionally includes a central timer  211 , which allows flush valve  13  to open and close according to a pre-programmed cycle that may be stored in central memory  212 . In embodiments incorporating multiple self-regenerating biofilters  100 , central timer  211  allows coordination between self-regenerating biofilters  100 . This ensures that at least one self-regenerating biofilter  100  is available for use at all times. This also allows self-regenerating biofilter system  200  to operate at peak capacity during peak gray water generation or demand times, such as, but not limited to, business hours in an office building or morning and evening in a residence, while reserving a smaller capacity for times when predicted demand is not as great. Central controller  210  optionally includes a central interface  213 , which may permit a user to enter commands to and receive output information from central controller  210  and/or controller  30 . 
         [0037]      FIGS. 3 a  and 3 b    illustrate an exemplary embodiment of a method  300  for using self-regenerating biofilter  100 . 
         [0038]    In step  302 , self-regenerating biofilter  100  receives an influx of untreated water stream  14  through intake inlet  11 . 
         [0039]    In step  304 , self-regenerating biofilter  100  filters untreated water stream  14  through filtration mass  20 , transforming it into purified water stream  15 . 
         [0040]    In step  306 , self-regenerating biofilter  100  expels purified water stream  15  through output outlet  12 . 
         [0041]    In step  308 , self-regenerating biofilter  100  stops receiving the influx of untreated water stream  14  through intake inlet  11 . 
         [0042]    In step  310 , self-regenerating biofilter  100  opens flush valve  13 . 
         [0043]    In step  312 , self-regenerating biofilter  100  drains flush water stream  16  through flush valve  13 . 
         [0044]    In step  314 , self-regenerating biofilter  100  closes flush valve  13 . 
         [0045]    In step  316 , self-regenerating biofilter  100  waits for a predetermined time period before continuing method  300 . 
         [0046]    In step  318 , method  300  repeats steps  302 - 316  n times, until method  300  meets a preselected condition. This condition may be for elapsed time, volume of water treated or amount of biomass in self-regenerating biofilter  100 . 
         [0047]    In step  320 , self-regenerating biofilter  100  receives an influx of untreated water stream  14  through intake inlet  11 . 
         [0048]    In optional step  322 , self-regenerating biofilter  100  receives air stream  42  through compressed air line  40 . Steps  318  and  320  may be performed simultaneously. 
         [0049]    In step  324 , self-regenerating biofilter  100  opens flush valve  13 . 
         [0050]    In step  326 , self-regenerating biofilter  100  drains flush water stream  16  through flush valve  13 . 
         [0051]    In step  328 , self-regenerating biofilter  100  closes flush valve  13 . 
         [0052]    It will be understood that many additional changes in the details, materials, procedures and arrangement of parts, which have been herein described and illustrated to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. 
         [0053]    It should be further understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. Moreover, the terms “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related.