Abstract:
Embodiments of the present invention provide a filtration system that can be used to filter debris-laden water and to systems for cleaning the filtration system using a vacuum flush system to create a backwash flow through the filter of the filtration system. The filtration system described finds particular use on-board passenger transport vehicles that have a vacuum waste system, such as aircraft. The filtration system provides the ability to collect, treat, and reuse liquid resources in an environment with a vacuum waste system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/727,371, filed Nov. 16, 2012, titled “Hybrid Grey Water Filtration Device” and of U.S. Provisional Application Ser. No. 61/729,225, filed Nov. 21, 2012, titled “Toilet Concepts,” the entire contents of each of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    Embodiments relate generally to a filtration system that can be used to filter debris-laden water and to systems for cleaning the filtration system using a vacuum flush system to create a backwash flow through the filtering component of the filtration system. The filtration system described finds particular use on-board passenger transport vehicles that have a vacuum waste system, such as aircraft. The filtration system provides the ability to collect, treat, and reuse liquid resources in an environment with a vacuum waste system. 
       BACKGROUND 
       [0003]    Water weight makes up the majority of the total net weight of potable water systems on-board aircraft and other passenger transport vehicles. During aircraft takeoff, this weight becomes particularly expensive in terms of fuel requirements. There exists a large incentive to reduce this weight. However, potable water is required for lavatory and galley uses. In the lavatory, potable water is required to wash users&#39; hands, but potable water is also used for the toilet flushing. It is desirable to provide a way to re-use the spent water from the hand-washing process on-board. During the hand washing process, after the potable water exits the faucet for rinsing the user&#39;s hands, the spent water (also referred to as “grey water”) is considered waste and is typically discharged overboard or introduced to the waste system. 
         [0004]    While the water being dispensed from the faucet is scrutinized by regulatory agencies for quality and health standards, the water used to flush the toilet is not under the same restrictions. There are no regulations preventing the use of this sink discharge, the “grey water,” for flushing the toilet. There may be other on-board uses for the grey water as well. Ground-based uses of collected grey water include flushing toilets, watering gardens, and other non-potable consumptions of water. However, these collection and re-use systems are ill-suited for aircraft installation due to health, structural, and environmental requirements. 
       BRIEF SUMMARY 
       [0005]    Embodiments of the invention described herein thus provide a mixed fluid filtration system. In one aspect, the filtration system is designed for aircraft non-potable reuse of grey water, but the functions and features described herein may be used in other instances for filtration of any other type of mixed fluid. Embodiments also provide a method for cleaning a filter of a mixed fluid filtration system using a vacuum system. The vacuum system may pull filtered water back into the filter (i.e., via backwashing) and into the vacuum waste system. This may help remove any debris or other solids from an inner surface of the filter media without having to remove and manually clean, scrape, or pressure wash the filter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1A  shows a side schematic view of a filtration system in the fill position. 
           [0007]      FIG. 1B  shows a side schematic view of the filtration system of  FIG. 1A  in the backwash position. 
           [0008]      FIG. 2  shows a side perspective view of a filtration system, showing the fluid reservoir, filter support, and valve. 
           [0009]      FIG. 3  shows a side view of a filter support according to one embodiment. 
           [0010]      FIGS. 4A-4C  show a filtration system having a deformable filtering component. 
           [0011]      FIG. 5  shows a side plan view of one embodiment for configuring an air intake for a filtration system. 
           [0012]      FIG. 6  shows a perspective view of a fluid reservoir and lid. 
           [0013]      FIG. 7  shows a perspective view of a filtration system installed beneath an aircraft lavatory sink and configured to deliver filtered grey water to an aircraft lavatory toilet for flushing. 
           [0014]      FIG. 8  shows a perspective view of a septic system using one example of a water capture and filtration system described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Embodiments of the present invention thus provide a mixed fluid filtration system. The system will generally be described for in filtering grey water on-board an aircraft for aircraft non-potable reuse of the grey water. However, it should be understood that the functions and features described herein may be used in other filtration systems for any other type of mixed fluid. 
         [0016]    As shown in  FIGS. 1-3 , the mixed fluid filtration system  10  includes a filtering component  12 , a fluid reservoir  14 , and a valve  16  for controlling flow of water that is filtered by the mixed fluid filtration system  10 . For example, the valve  16  may be in fluid communication with a vacuum waste tank  30 . When the valve  16  is closed, the filtered water stored in the fluid reservoir  14  may be delivered to a holding tank or intermediate reservoir that may be used to store the filtered water for use in toilet flushing or for other on-board uses. This configuration is shown in  FIG. 1A . When the valve  16  is open, as shown in  FIG. 1B , the filtered water in the fluid reservoir  14  may be subjected to vacuum. This pulls the filtered water back in through the filtering component  12  to create a backwash for cleaning the filtering component. This inward flow is shown by arrows F, showing water flowing into the filtering component  12  and into the vacuum waste system  30 . 
         [0017]    Referring now more particularly to each component of the system  10 , the filtering component  12  includes a filter support  22  and a filter media  24 .  FIG. 2  shows a filtering component  12  positioned in a fluid reservoir  14 . The filter support  22  has a first end  18  that is configured to receive water from a mixed fluid outlet. One example of a complete installed system is shown in  FIG. 7 . In one embodiment, the mixed fluid outlet may be a drain of an aircraft sink basin. When used on-board an aircraft, the mixed fluid filtration system  10  collects and treats liquid discharge from sinks, other grey water production fixtures, or any other influent water chamber. After a passenger washes his/her hands, rather than having the spent grey water routed directly to the waste tank via the on-board vacuum waste system or routed overboard, the water can be captured and cleaned by the mixed fluid filtration system  10  in order to route the water for other uses. One example of use of the filtration system  10  is a complete septic system for re-use of the filtered water for toilet flushing is shown in  FIG. 8 . 
         [0018]    Grey water enters the first end  18  of the filtering component  12  via gravity and is directed to the treatment chamber  20 . In one embodiment, the first end  18  may be secured directly to a sink basin drain D or it may be secured to an intermediate component between the basin and the remainder of the filtration system  10 . One or more sealing elements (such as o-rings) are generally used at the first end of the filtering component  12  in order to ensure a liquid tight seal and prevent leakage. Water may enter into a treatment chamber  20 , which is a space that may be formed between the filter support  22  and a filter media  24 . A second end  19  of the filter support  22  is configured to cooperate (typically indirectly via tubing) with a valve  16  that is in communication with the vacuum waste system. 
         [0019]    One example of a filter support  22  is shown in  FIG. 3 . The filter support  22  is shown having one or more ribs  26  which function as support features. The ribs  26  may be formed as one or more protrusions from a central spine  28  of the filter support  22 . The filter support  22  may be a rigid support structure or a dynamic and deformable structure. A deformable structure has the added benefit of temporarily accommodating a larger inrush of grey water or other mixed fluid into the treatment chamber  20 , allowing more time for the water to pass across the filter media  24 . This deformability may also help extend the filtering component  12  lifetime by loosening accumulated particulates from its various surfaces as the filter support flexes. 
         [0020]      FIGS. 4A-4C  shows a fluid reservoir  14  that is defined by a deformable filtering component  52 . The deformable filtering component  52  adjusts the shape of the treatment chamber  20  depending on the prevailing conditions (pressure, water level) in the treatment chamber  20  and fluid reservoir  14 . In one embodiment, deformability may be achieved by resistive hinges  60  and/or flexible gaskets on the filter support  22 . These hinges  60  may allow the filter support  22  to flex inwardly or outwardly, depending upon the volume of the water column and thus, the pressures applied to the filtering component  12 . In a preferable system, the filter media  24  is also deformable, such as a polymer or plastic or other material, that can flex and deform with the filter support  60 . 
         [0021]    A filter media  24  may be secured to the filter support  22 . The structure of filter support  22  allows various different types of filter media  24  to be used therewith. Incoming mixed (or grey) water is driven through the treatment chamber  20  formed between the filter support  22  and the filter media  24 , and driven across the filter media  24 . The filter media  24  is designed to retain selected particle sizes from the incoming water, depending upon the filter media  24  type. In one embodiment, the filter media  24  comprises a metal or polymer filtration structure that retains particulate matter and reduces foam in the water. Other embodiments provide filters that may be paper-based, such as lab filter paper. 
         [0022]    The filter media  24  may be formed as a screen or any sieve-like structure that filters out unwanted particles and debris. The filter media  24  may be designed to retain various particle sizes specific to the input liquid and the output requirements and to prevent them from passing out of the treatment chamber  20  and into the fluid reservoir  14 . In one embodiment, the filter media  24  may include multiple stages of coarse to fine filter media. One specific example is a 500 micron filter followed by a 250 micron filter. The filter media  24  may be impregnated with silver or other antimicrobial metallic material to reduce the risk of microbial contamination and propagation. Additionally or alternatively, the filter media  24  may be coated with a combination of hydrophobic and/or hydrophilic materials to passively discriminate between water and surfactants. This may assist the migration of the treated/cleaned/filtered grey water through the filter media  24 . The water is allowed to flow out from the filter media  24  into the fluid reservoir  14 . Any undesired solids are generally filtered out and retained along an inner surface of the filter media  14 , such that the water exiting the filtration component  12  is generally filtered, cleaned, or otherwise configured to be delivered to a use location for re-use. 
         [0023]    The filter media  24  may be secured to the filter support  22  using any appropriate method. For example, the filter media  24  may be adhered to the filter support  22  via an adhesive, such as epoxy. Alternatively, an edge of the filter media  24  may be inserted into a lip formed on the filter support  22 . Additionally or alternatively, the filter media  24  may be formed such that it slides over the filter support  22  and is secured in place via a cap or clip or other securing structure. Any other securing options are possible and considered within the scope of this disclosure. 
         [0024]    The treated or filtered grey water is stored in the fluid reservoir  14  where it awaits use in non-potable water applications (or in potable drinking water applications if the filter treatment has been sufficient to render the water potable). The filtered fluid is held in the fluid reservoir  14  and is available for downstream use via a fluid connection. In use, the valve  16  remains is a normally closed position. 
         [0025]    As shown in  FIG. 1A , the normally closed valve  16  prevents the fluid reservoir  14  from being subjected to vacuum from the vacuum system  30 . Valve  16  may be a pinch valve or any other appropriate valve  16  that creates an interface between the vacuum system and the treatment chamber  20  of the system  10 . Valve  16  may be controlled via a solenoid or any other appropriate controlling system or mechanism. When the valve  16  is closed, water can be delivered out of the fluid reservoir  14  via outlet  32 . Outlet  32  may deliver water to a filtered grey water pump or other filtered grey water reservoir. 
         [0026]    In one embodiment, a level sensor system  34  may be provided in the mixed media filtration system  10  order to determine the water levels in the treatment chamber  20  (e.g., as the mixed water “waits” in the chamber prior to being forced out through the filter media  24 ) and/or in the fluid reservoir  14 . One or more level sensors  34  may be used to communicate the availability of treated water or accumulation of influent fluid. Level sensors  34  may be comprise non-intrusive or intrusive sensors, such as capacitive sensors, ultrasonic sensors, pressure switches, float switches, any other appropriate level sensor, or any combination thereof. If fluid in the fluid reservoir  14  reaches a low level, a low level sensor may be activated to indicate that a re-fill is needed. The low level sensor may trigger a refill from the potable water system to ensure the availability of water for downstream use. 
         [0027]    If fluid in the fluid reservoir  14  reaches a high level (which may be a pre-set high fluid level volume, based on the size of the reservoir  14  and other needs of the system  10 ), the reservoir  14  may be partially or fully emptied. This emptying may assist in preventing overflow or back-up into the basin or other influent water location. The emptying process may also assist in cleaning the filter media  24 . A high level sensor may trigger a full or partial emptying process to the vacuum waste system  30  to ensure that the reservoir  14  does not overflow. The level sensing and control of the fluid reservoir  14  are generally automated in the aircraft environment. In other embodiments, power may not be accessible and the sensing and control can be controlled by other means. For example, level switches such as float switches may be used to detect fluid level, and any emptying and refilling of the reservoir may be accomplished manually. 
         [0028]    If the system  10  is installed for use in collecting grey water from a sink basin on an aircraft, the filtered water being held in the fluid reservoir  14  may be delivered to a filtered grey water holding tank for use in flushing the vacuum toilets or other uses on-board. However, if those uses are not required and excess water builds up in the fluid reservoir  14 , then filtered water in the reservoir  14  may be delivered to the aircraft vacuum waste system during a partial or full emptying process of the fluid reservoir  14 . This emptying process also functions as a filtering component  12  cleaning process. Any particles retained by the filtering component  12  and/or on an inner surface of the filter media  24  may be disposed of (and consequently, the filtering component  12  may be cleaned) via backwashing fluid from the fluid reservoir  14  into the vacuum waste system  30 . Additionally, at least a partial emptying process may be activated periodically in order to clean the filtering component  12 , even if the level sensors  34  do not indicate a high level. 
         [0029]    For example, accumulation of particulate matter and foam in the treatment chamber  20  and on the filter media  24  is addressed by periodically flushing the contents into the vacuum waste system  30  while backwashing the filtering component  12 . A backwash of the filtering component  12  is accomplished using the remaining treated water present in the fluid reservoir  14  and the pressure differential. In use, the valve  16 , which is normally closed, is allowed to open. The valve  16  operates as the controlled interface to the vacuum waste system  30 . Additionally, an inlet restrictor  36  located at the inlet  30  to the mixed fluid reservoir  14 , closes during the backwash cycle as shown in  FIG. 1B . This keeps air from entering on the fouled side of the filtering component  12 , and instead directs air backwards across the filtering component  12  via a vent  62  in the fluid reservoir  14 . One example of such a vent  62  is shown in  FIG. 6 . This vent  62  may act as an inlet for air to enter the fluid reservoir  14 . It may vent to the atmosphere or it may cooperate with an odor-control device to clean any air that may vent out. 
         [0030]    The movement of air drawn by the vacuum waste system  30 , dislodges accumulated particulates and cleans the filtering component  12 . This cycle is triggered when the fluid level in the fluid reservoir  14  is high, and/or at a given interval for periodic filter cleaning For example, at least a partial emptying process may be activated via a time-based system (i.e., every 2 hours) or via a flush-based system (i.e., every 100 flushes) or via a volume-based system (i.e., every time 20 or more gallons of water have been filtered) or any other appropriate indicator to ensure that the filtering component  12  is cleaned, even if a high fluid level is never reached in the reservoir  14  due to consistent end uses of the filtered water contained therein. 
         [0031]    The valve  16  and inlet restrictor  36  generally require power and operate automatically in an aircraft setting. In the environment without access to a vacuum waste system or to power, the valves and backwashing may be achieved manually. 
         [0032]    Escape of gaseous odors from grey water or other mixed fluid is a concern for aircraft passengers and crew or any other users. Unpleasant odor can be addressed by the delivery of chemical additives and/or biocides, which may be housed in a chemical additive unit  40 . For example, a chemical destabilizer comprised of Enviroclean or a chemical with similar properties may be added periodically to prevent reservoir and toilet bowl staining and to improve filtration performance. A delivery system for the additives to the fluid reservoir  14  may use a metered pump  42 . In one embodiment, the chemical supply may be provided in a replaceable additive unit  42 . Replacement may be accomplished, for example, by removing the storage unit and replacing the input line. In another embodiment, the additive unit  40  may be refillable. 
         [0033]    Odor may also be reduced by providing an odor-absorbent and/or odor-adsorbent liner in the lid  44  of the fluid  14  reservoir. Certain materials, such as activated carbon felt, absorb constituents from the air around the mixed fluid which contribute to foul odor. Reducing the concentrations of these contaminants in the air can help minimize this odor. Odor emanation may be further prevented with an odor-control  46  device positioned between the sink discharge point and the fluid reservoir  14 . This device  46  may provide a one-way check to allow the passage of liquids under the force of gravity, while preventing the upward passage of any gasses or foams. One such device  46  may be comprised of an elastomeric skirt structure  58 . The weight of the incoming mixed fluid pushes the elastomeric skirts  58  aside as the fluid flows into the fluid reservoir  14 . The skirts return to their initial position once the weight of the fluid has passed, blocking any outflow of gases, foams, or fluid. 
         [0034]    A further embodiment shown in  FIG. 5  may include an air intake tube  54  in fluid communication with the fluid reservoir  14 . The air intake tube  54  may be necessary in order to equalize the environment in the reservoir  14 . Because a strong vacuum is applied to the reservoir  14 , there must also be a way to replace the air into the reservoir  14 . An air intake tube  54  is thus provided. 
         [0035]    In one configuration, an additional component surrounding the filter cartridge could act to improve the backwash process by concentrating the airflow and controlling its velocity to ensure its efficacy. This component generally could be a cylinder, or another shape that would surround the filter cartridge to direct airflow evenly around the filtration surface. An inlet vent may be plumbed to the outside of the filtration reservoir  14  to serve as a source of incoming airflow. The outlet may be a hole or series of holes that direct air across the filtration media  24 . The outlet may be any shape such as circular, elliptical, rectangular. 
         [0036]    The specific embodiment shown in  FIG. 5  features a spiral cage  56  that functions as this additional component. Spiral cage  56  extends down the filtering component  12 , within the treatment chamber  20 . This embodiment uses the air that is pulled in through the air intake tube  54  and directs the air in a downward spiral fashion so that the air can also help clean the filter media  24  during the cleaning/backwash process. 
         [0037]    In one embodiment, the mixed fluid filtration system  10  is constructed from plastic materials to achieve the low weight required for aircraft applications. A specific design of the system  10  designed for aircraft usage may be about five pounds, including valves, sensors, and controllers. The size of the system  10  is dictated by the space envelope available in the lavatory and/or galley structure into which the system  10  is to be installed, at the point of use of the filtered fluid. The storage volume within the fluid reservoir  14  is kept to a minimum in order to reduce the residence time of collected water and to lower the risk of microbial propagation. One example of an internal volume of the reservoir  14  designed specifically for aircraft lavatories is about one gallon, but it should be understood that the system  10  and related fluid reservoir  14  can be designed to meet the collection needs for other applications of the system  10 . The reservoir may be larger or smaller if desired. 
         [0038]    Maintenance of the system  10  may be addressed by using an installation comprising quick-release interfaces and a hinged support structure allowing ease when pivoting the mixed fluid filtration system  10  from its installed position to a maintenance position. Once engaged in the maintenance position, an airtight lid  44  can be removed from the top of the fluid  14  reservoir which exposes and allows the removal and replacement of the filtering component  12 . This process may be aided by a number of maintenance features comprising handles and quick-release latches, which are generally known to those of ordinary skill in the art and need not be described further herein. 
         [0039]    A further sensing system may be provided in order to detect when the filtering component  12  has reached the end of its useful lifetime. For example, at least one level sensor may be fixed such that it can measure the height of the fluid in the treatment chamber  20 . Water may accumulate in the treatment chamber  20  as it waits to pass through the filter media  24 . At least one other sensor measures the height of fluid in the fluid reservoir  14 . When the filtering component  12  blocks fluid passage to the point that the influent level in the treatment chamber  20  is a predetermined amount higher than the storage level in the fluid reservoir  14 , even after a backwash, the sensing system will indicate that the filtering component  12  (or the filter media  24  portion of the filtering component  12 ) needs to be replaced. This indication can be in a form such as a light or display, or it may communicate with the overhead system and/or operator. 
         [0040]    A method for use of the system  10  is now provided.  FIG. 1A  shows the mixed fluid filtration system  10  in a filling configuration. The sink discharges grey water through a coarse grill or grate that functions to keep large items out of the fluid reservoir  14 . The grey water then passes through an odor-control cartridge  46 . The weight of the grey water pushes the elastomeric skirts  58  aside as it cascades through the cartridge  46 . The skirts return to their initial position once the weight of the water has passed. Grey water then pushes the inlet restriction  36  aside as it pours into the fluid reservoir  14 . The inlet restriction  36  may be provided as a dynamic hinged check. 
         [0041]    The pressure of the water in the treatment chamber  20  creates a pressure that pushes the grey water across the filtering component  12 , and particularly across the filter media  24 . The filter media may be a hydrophobic/philic membrane, leaving any particulate matter and soaps behind (on the inner surface of the filter media  24 ). Once the level sensor  34  has determined that a sufficient volume of filtered grey water has accumulated, the water can be delivered to a use location from the fluid  14  reservoir via outlet  32 . In one embodiment, the fluid is delivered to an aircraft vacuum toilet for flushing. 
         [0042]      FIG. 1B  shows the mixed fluid filtration system  10  in a backwashing configuration. To flush the contents of the fluid reservoir  14 , the system opens a solenoid  50 , exposing the pinch valve  16  to vacuum and forcing it open. This vacuum action pulls the contents of the treatment chamber  20  into the vacuum waste system  30 , pulling the filtered grey water backwards across the filter media  24  and into the filtering component  12 . This action backwashes the filtering component  12  and renders it cleaned for the next use. 
         [0043]    In one aspect, there is a system for filtering grey water and for delivering the filtered gray water that is cleaned and captured to flush a vacuum toilet.  FIG. 8  illustrates an overall view of one exemplary use of the system. To connect the filtered grey water to the existing toilet, the use of a water pump “P” and an accumulator “A” fitted with a rinse valve may be provided. Filtering of the grey water may be accomplished with a cylindrical filter that is housed in a canister. The grey water comes in through the center of the filter. When a grey water interface valve  16  is closed, the water pump P creates a pressure differential across the filter to facilitate filtration. The water pump P also pumps filtered water into an accumulator A in preparation for the next flush. As flush is required, the outlet valve of the accumulator A opens to discharge rinse water captured in the accumulator A. 
         [0044]    With the grey water interface valve  16  open, the filter reject (including debris, hair, solids, soap, etc.) can be evacuated through the grey water interface valve  16  into the waste system  30 . Opening of the grey water interface valve  16  also facilitates a back wash of the filter using the filtered water. 
         [0045]    An example of an alternate use for the filtration system  10  described is in an environment where potable water is not available. In such a scenario, a vacuum system may similarly not be available. The system could then be operated manually to filter and treat the water of non-potable quality in order to provide potable water for drinking 
         [0046]    In order for manual operation of the system  10  to occur, a pressure differential between the filtered water (outside the treatment chamber  20 ) and the grey water inside the treatment chamber must be effected. In the absence of a vacuum (which can create the desired pressure differential), an alternate method may be used. For example, in one alternate, a pressure bulb may be provided on the filtered side of the water to increase the pressure differential across the filter media  24 . Once the pressure is greater on the filtered water side, the filtered water may be caused to move back through the filtering component, creating the desired backwash. Another option may be to manually displace the water across the filtering component, for example, via a pressure system or a strong water flow. In these embodiments, rather than moving from ambient to vacuum, the backwash may be created by moving from a high pressure system to ambient. 
         [0047]    Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the invention and the following claims.