Abstract:
A method of treating water which comprises, forming a mixture of a particulate natural organic substrate with a flow control component, exposing the water to contact with oxygen containing gas over a large surface area, and causing the water to trickle through a column of the mixture, wherein the particulate natural organic substrate is adapted to support growth of aerobic bacteria and the flow control component is adapted to create a plurality of sinuous pathways for the water trickling through the column.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to water treatment processes and devices. In specific non-limiting aspects it relates to methods of treating grey water and lightly polluted stormwater, cartridges for treating grey water and grey water treatment assemblies.  
       BACKGROUND OF THE INVENTION  
       [0002]     Human use of water resources has been increasing in response to increasing human population, agriculture and industrialization. However, the amount of fresh water available for use from rivers, lakes and subterranean basins is a comparatively limited amount on a worldwide basis. Clearly the world population cannot go on increasing indefinitely without putting impossible strains on the current sources of fresh water.  
         [0003]     In order to alleviate water shortages, authorities are increasingly relying upon using treated recycled water otherwise known as grey water for all sorts of purposes, particularly where a high quality water resource is not required. Such is the case for watering of lawns, gardens or other similar low risk activities around the dwelling or site. Where public authorities are involved in recycling of water, there needs to be a substantial infrastructure for piping grey water from consumers to a recycling plant and then to an area where it can be used profitably. Whilst this might be a suitable approach for large public or commercial operations, approaches for recycling grey water on a domestic basis for use within a household where the grey water has been generated, are not generally practical. This is due to the lack of readily available domestic grey water treatment systems, the space they occupy and the high cost of installing and maintaining such systems.  
         [0004]     Thus, there is a need for an approach for water treatment which may be particularly applicable to grey water and which may be useful in a domestic recycling environment.  
         [0005]     Suitably, the approach should involve equipment which does not require substantial maintenance, does not have a large footprint, is easy to operate and is relatively inexpensive.  
         [0006]     The present invention seeks to provide a method and devices which go some way towards meeting one or more of these objectives.  
       DISCLOSURE OF THE INVENTION  
       [0007]     The invention provides in one aspect a method of treating water which comprises, forming a mixture of a particulate natural organic substrate with a flow control component, 
        exposing the water to contact with oxygen-containing gas over a large surface area, and     causing the water to trickle through a column of the mixture,     wherein the particulate natural organic substrate is adapted to support growth of aerobic bacteria and the flow control component is adapted to create a plurality of sinuous pathways for the water trickling through the column. The oxygen-containing gas may comprise air.        
 
         [0011]     The sinuous pathways may comprise the large surface area for oxygen/water contact.  
         [0012]     Suitably the biologically-active substrate is also adapted to support growth of anaerobic and facultative bacteria. The biologically-active substrate may be inoculated with live aerobic bacteria prior to use in the column.  
         [0013]     The particulate natural organic substrate may comprise peat, moss, sphagnum moss, compost, lichen, straw, hay, mulch, pulp, rice husks, wheat husks or mixtures of any two or more of the foregoing.  
         [0014]     The mixture may be a mixture of an inorganic particulate substrate and a particulate natural organic substance.  
         [0015]     In a particular aspect of the invention, the particulate natural organic substrate may comprise peat. The inorganic component may comprise any one or more of PVC, polyethylene, polypropylene or any other suitable component presented in a form where it has a high surface area.  
         [0016]     The flow control component may comprise a particulate material which is distributed throughout the column. For example, it may comprise particulate or shredded organic or inorganic material. It may comprise shredded plastic. It may comprise PVC, polyethylene, polypropylene or other suitable material having a high surface area per unit volume.  
         [0017]     Additionally or alternatively, the flow control component may comprise one or more tiers of impermeable material arranged throughout the column. Additional flow control means may also be used. The additional flow control means may comprise different layers of particulate materials. For example, they may comprise one or more flow control canisters stacked one above the other, above the column. The flow control canisters in combination with the column may be constructed as a cartridge.  
         [0018]     The uppermost canister may contain media which allow for high contact between the water and air. For this purpose it may comprise a material having an average contact surface area per cubic metre above 250 m 2 /m 3 . It may comprise particulate material, mesh material, structurally moulded materials or mixtures of any of these.  
         [0019]     The middle canister may contain media having a higher surface contact area than the media in the uppermost canister. Suitably, its average surface contact area should be at least 1.5 times that of the media in the uppermost canister.  
         [0020]     The column below the canisters may contain the mixture of particulate natural organic substrate and flow control component. Typically the ratio of organic substrate to flow control component will be in the volume range of 1:4 to 2:1, more suitable it may be about 2 to 3. The volume/surface area of the mixture is suitably greater than the volume surface area of the middle canister. The flow control component may typically have a surface area per cubic metre volume greater than 250 m 2 /m 3 , more preferably greater than 375 m 2 /m 3 .  
         [0021]     The column, canister or cartridge may include inflow means for allowing an oxygen containing gas such as air to percolate through the column. Suitably, the inflow means may allow the air to percolate upwards through the column, canister or cartridge whilst allowing water to percolate down through the column. The inflow means may comprise a perforated or porous tube extending into the column, canister or cartridge. Alternatively or additionally the inflow means may comprise a porous container for holding the column, canister or cartridge.  
         [0022]     In another aspect, the invention provides a cartridge comprising a column as hereinbefore described. It may be housed within a porous container comprising a geotextile and/or similar material serving the containment purpose. Alternatively, it may comprise a non-porous plastic container with open top and bottom. The air inflow means may extend through the container into the column in the form of a perforated tube. It may also comprise the geotextile which is itself porous.  
         [0023]     The column may include secondary distribution means for the water being treated in the column. The secondary distribution means may comprise a funnel which directs water to a position intermediate the height of the column. There may be a plurality of such funnels. The one or more funnels may extend from a position at the top of the column into a region substantially at the midpoint of the height of the column.  
         [0024]     Alternatively, they may be arranged so as to deliver the water for treatment at a number of equally spaced heights in the column. Thus for example, water may be arranged to percolate directly into the top of the column whilst a proportion of the water may be directed into the top third of the column by one or more funnels and to a bottom third of the column by one or more additional funnels.  
         [0025]     As a means of providing additional treatment, as sometimes required for a higher quality final effluent, the process may include a further form of treatment. This treatment would be placed in a location where the effluent must pass through it after the primary process, this unit may be attached, or not, depending upon the final effluent quality required. This final treatment process may be in the form of disinfection produced by introducing a chemical (such as chlorine) into the outflow and allowing a retention time for desired treatment activity to take place. The vessel designed to facilitate this could be placed at a point where the outflow can be collected to a common stream. Suitably this may be before the final storage. The vessel may take the shape of a cylinder or something similar and be placed horizontal, vertical or at an angle between. The storage may allow for contact between the treated waste and an active chemical so as to allow for a suitable amount of mixing after contact. The chemical may be introduced with a form of pumping, siphon, venturi or air injection whichever may be appropriate for a particular installation.  
         [0026]     In another aspect the invention provides a grey water treatment assembly comprising, 
        a collection reservoir for grey water,     a treatment module comprising a column as hereinbefore described,     a delivery system for feeding the grey water from the collection reservoir to flow through the treatment module, and     a storage reservoir arranged to receive treated grey water after it has passed through the treatment module.        
 
         [0031]     The treatment assembly may comprise a plurality of treatment modules. The treatment modules may comprise cartridges each removably retained within a cartridge casing held in a treatment tank. Thus, the treatment tank may include one or more cartridge casings for receiving a varied number of cartridges and an equal number of showerheads or distribution sprays for directing water for treatment to flow through the columns and any funnels provided at the top of the column. The water may come from the shower heads provided above the cartridges, or from the pipe system below and through distribution sprays.  
         [0032]     The casings may include a spigot for fitting into a tube formed at the bottom of each cartridge casing to allow oxygen containing gas such as air to permeate upwards through the cartridge.  
         [0033]     Preferred aspects of the invention will now be described with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]      FIG. 1  shows an elevational view of a vertical section taken through the centre of a cartridge according to the invention;  
         [0035]      FIG. 2  shows a vertical section taken through a funnel for use with the cartridge;  
         [0036]      FIG. 3  shows a vertical section taken through a treatment tank for use with the invention;  
         [0037]      FIG. 4  shows the section A taken through the dispersion manifold shown in  FIG. 3 ;  
         [0038]      FIG. 5  shows the section B taken through  FIG. 3 ;  
         [0039]      FIG. 6  shows a concept drawing of the operation of the treatment tank shown in  FIG. 3 ;  
         [0040]      FIG. 7  shows a concept drawing of a treatment assembly according to the invention;  
         [0041]      FIG. 8  shows an elevational view of a vertical section taken through the centre of an alternative form of cartridge according to the invention;  
         [0042]      FIG. 9  shows a plan view taken from the top of the cartridge of  FIG. 8 ;  
         [0043]      FIG. 10  shows a plan view taken from the base of the cartridge of  FIG. 8 ; and  
         [0044]      FIG. 11  shows a concept drawing of a treatment tank/module using the cartridges shown in  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]     The various elements identified by numerals in the drawings are listed in the following integer list.  
       INTEGER LIST  
       [0000]    
       
           1  Cartridge  
           3  Outer wall  
           4  Filling  
           5  Central tube  
           7  Hole  
           9  Flange  
           10  Fuse joint/mechanical joint  
           11  Distributor funnel  
           12  Location point  
           13  Treatment tank  
           15  Outer casing  
           16  Dispersion manifold  
           17  Cartridge casing  
           20  Inlet tube  
           22  Holes  
           24  Shower head  
           25  Shower holes  
           26  Seal  
           27  Spigot member  
           29  Outlet  
           30  Open region  
           31  Air passage  
           32  Air inlet  
           33  Motor  
           34  Air outlet  
           40  Inlet pipe  
           42  J tube  
           43  Valve  
           46  Collection reservoir  
           48  Vent  
           49  Vent/overflow pipe  
           51  Removable sealing cap  
           52  Valve  
           53  Power source (solar)  
           54  Pump  
           55  Motor  
           56  Variable speed drive  
           57  Timer  
           58  Flowswitch  
           61  Coarse strainer  
           63  Outlet line  
           65  Storage reservoir  
           66  Overflow line  
           67  Valve  
           68  Reuse line  
           69  Valve  
           70  Valve  
           71  Recycle line  
           72  Air  
           74  Valve  
           76  Extra treatment station  
           80  Cartridge  
           82  Column  
           83  Middle canister  
           84  Upper canister  
           85  Container  
           87  Hollow  
           89  Neck  
           90  Step  
           91  Base  
           93  Hole  
           95  Annular pad  
           97  Organic media  
           98  Inorganic media  
           99  Inorganic media  
           101  Air conduit  
           102  Outlet holes  
           103  Water conduit  
           104  Seal  
           105  Sprinkler assembly  
           106  Outer wall  
           108  Sprinkler head  
           109  Sludge trap  
           110  Air inlet line  
           112  Fan/pump  
           114  Inlet pipe  
           116  Outlet line  
           118  Air outlet  
           120  Treatment tank/module  
       
     
         [0125]     Referring to  FIG. 1 , the cartridge generally designated  1  shown therein comprises an outer wall  3  of a gas permeable material such as geotextile fabric.  
         [0126]     The geotextile fabric holds the filling  4  which comprises the treatment agent in the form of a column held in the cartridge. The filling may typically comprise a natural organic particulate material which acts as a substrate for aerobic bacteria. It has been found that peat can be quite effective as an organic substrate for aerobic and anaerobic bacteria.  
         [0127]     Mixed with the particulate peat forming the filling is a material which tends to bulk up the peat and create sinuous pathways through the peat for water tricking through the peat whilst at the same time leaving the filling material sufficiently porous to allow air to percolate upwards through the peat. This ensures for a high contact area between the water and air. Particulate shredded plastics mesh material has been found to be very suitable for this purpose.  
         [0128]     In addition to the effect achieved by the shredded mesh, the cartridge is provided with a number of flanges  9  surrounding a central tube  5 . These flanges also help to divert water flowing down through the cartridge and air percolating upwards from what might otherwise be relatively straight flow paths. They are formed around the central tube  5 . They are designed to allow air to travel up through the tube and to pass through a number of holes  7  formed along the length of the tube into the filling in the cartridge.  
         [0129]     One of more distributor funnels  11  shown in  FIG. 2  may be pushed through the geotextile material at location points  12  on the top of the geotextile material. The distributor funnel or funnels may be added so as to direct a proportion of water flowing onto the top of the cartridge into an intermediate position in the height of the filling in the cartridge. It has been found that use of funnels in this fashion can improve the efficiency of water treatment by the cartridge depending of course upon the height of the treatment cartridge used.  
         [0130]     The geotextile material forming the outer wall  3  of the cartridge may be joined to the lowermost flange  9  surrounding the central tube  5  by a circular fuse joint or mechanical joint  10 . This holds the central tube within the outer wall gives a degree of structural rigidity to the cartridge when it has been filled with filling  4 .  
         [0131]     Referring to FIGS.  3  to  5 , there is shown a treatment tank generally designated  13  which is set up so that it can removably receive three separate cartridges, the cartridges being individually replaceable as and when they have reached the limit of their useful effective life.  
         [0132]     The treatment tank  13  forms a module for the treatment of grey water. It comprises an outer casing  15  formed of a material such as plastics, particularly rotationally moulded plastic. It has a dispersion manifold  16  which acts as lid to seal off the top of the outer casing.  
         [0133]     Three cartridge casings  17  are arranged within the outer casing.  
         [0134]     These cartridge casings  17  are each formed with a spigot member  27  adapted to co-operate with the central tube  5  of each cartridge so as to provide an entry point for air to the central tube and to correctly locate the cartridge within the cartridge casing.  
         [0135]     The outer casing  15  has an air inlet  32  which may optionally include a motor  33  for operating a fan to drive air through the inlet. The air inlet communicates with the open region  30  formed between the base of the cartridge casing  17  and the bottom of the outer casing  15  to act as ducting for allowing air to travel from the inlet  32  through the spigot  27  and air passage  31 .  
         [0136]     The dispersion manifold  16  includes a seal  26  for sealing off the top of the outer casing.  
         [0137]     An inlet tube  20  for delivering grey water extends through the centre of the dispersion manifold and includes a number of holes  22  for allowing grey water to flow down into the showerheads  24  formed at the bottom of the dispersion manifold. A number of shower holes  25  are arranged to evenly distribute grey water to the top of the cartridges  1  and any funnels held in the cartridge casing  17 .  
         [0138]     Each of the cartridge casings has an outlet  29  for allowing treated water which has passed through a cartridge to be drawn from the treatment tank. Similarly, an air outlet  34  is provided at the top of the outer casing  15  to allow air which has percolated through the cartridge casing to exhaust from the treatment tank.  
         [0139]     Referring to  FIG. 6 , it can be seen that the general arrangement of cartridges within the treatment tank allows grey water to enter each of the cartridges via the holes  22  in the showerhead or sprays  24  and to trickle down through the cartridges in a circuitous path. The shredded mesh material forming part of the filling for the cartridge and the flanges  9  contribute to ensuring that the flow of water through the cartridge is circuitous.  
         [0140]     Whilst the water is flowing downwardly, air  72  from the central tube  5  and through the porous walls of the cartridge  3  permeates upwardly through the cartridge creating aerobic conditions for bacteria held on and within the peat in the filling. The aerobic bacteria digest unwanted components of the grey water and hence purify and deodorize it.  
         [0141]     The treatment assembly of  FIG. 7  may be used to treat grey water from one or more domestic sources. It includes a treatment tank  13  as described with reference to FIGS.  3  to  6 , and an inlet pipe  40  connected via a J-tube  42  and valve  43  to a collection reservoir  46 . A vent  48  and vent overflow pipe  49  are connected to the inlet pipe for grey water as is known in the art. A removable sealing cap  51  is also provided on a separate extension of the inlet pipe  40 .  
         [0142]     The collection reservoir  46  is arranged to direct grey water collected from a household or any other source as and when needed through the inlet tube  20  and valve  52  by means of a pump  54  driven via a motor  55  having a variable speed drive  56 . A power source  59  such as a solar collector provides power for the pump and a timer  57  can be used to set appropriate times for when the motor should operate.  
         [0143]     As a precaution, a flowswitch  58  may be provided to sense flow through the inlet tube  20  and to shut off the motor when flow from the reservoir  46  stops as a result of the reservoir being empty.  
         [0144]     A coarse strainer  61  is provided to strain off coarse materials from the grey water before it enters the treatment tank  13 .  
         [0145]     A valve  74  is associated with the outlet  29  of each cartridge casing to allow testing of treated water which has passed through the cartridge. The cartridges  1  may be replaced individually as and when testing shows the water quality exiting the cartridge has gone below a predetermined level.  
         [0146]     The combined output of water from the cartridges passes through valve  69  to the outlet line  63  and on to a storage reservoir  65  for the treated water.  
         [0147]     Optionally an extra treatment station  76  which includes a disinfection process may be included.  
         [0148]     An overflow line  66  sends excess water to waste when the storage reservoir has been filled to capacity.  
         [0149]     Water can be drawn from the storage reservoir  65  as and when needed through the reuse line  68  after it passes through the valve  67 .  
         [0150]     The treatment assembly may include the option of recycling water to the collection reservoir  46  should the quality of the water exiting the treatment tank not be at a desired level. Thus the system may include a recycle line  71  through valve  70  to return water to the reservoir  46  ie. when valve  69  is closed and valve  70  is opened, water will return directly to the reservoir  46 . Alternatively, when valve  70  is closed and valve  69  is opened, treatment water will go directly to the storage reservoir  65  or the overflow line  66  as the case may be.  
         [0151]     Referring to  FIGS. 8, 9  and  10 , there is shown a cartridge generally designated  80  which comprises three main components, namely a column  82 , a middle canister  83  and an upper canister  84 . For ease of construction, the column, middle and upper canister may be formed of similar containers  85  which can be stacked one on top of the other in the manner illustrated. Typically, the containers may be moulded from plastics material.  
         [0152]     Each of the containers  85  includes a hollow  87  formed centrally in the base  91  of each container. The hollow extends upwardly and narrows to form an open-ended neck  89 .  
         [0153]     The base of the containers is also formed with a step  90  to assist with location of the containers when they are stacked one on top of the other. Whilst the two canisters and column for the purposes of this specification are considered to be a cartridge, it is to be appreciated that these three components may be configured together to form a cartridge by stacking them one on top the other without physically binding them together.  
         [0154]     The base of each container is provided with a number of holes  93 . An annular pad  95  of a porous material such as geotextile fabric or a similar fibrous mesh or filter material is placed on top of the base so as to allow drainage of water through the pad and holes.  
         [0155]     The lowermost container  85  comprising the column  82  is filled with organic media  97  mixed with a flow control component. Typically, the organic media may comprise particulate peat. The flow control component may comprise sand, crushed aggregate or any other material which presents a high surface area per unit volume and which creates a plurality of sinuous pathways for water trickling through the column. Examples of flow control materials may include particulates, moulding or mesh. Typically, the volume of the peat to the flow control component falls within the range 1:4 to 2:1. Furthermore, the mixture of peat and flow control component suitably has an average surface area per unit volume of at least 375 m 2 /m 3 .  
         [0156]     The middle canister contains inorganic media  98  which may typically comprise a material such as gravel having an average surface area per unit volume of at least 375 m 2 /m 3 .  
         [0157]     The upper canister  84  may contain inorganic media having an average contact surface area per cubic metre volume greater than 250 m 2 /m 3 . Suitably, it may be a very open form of media. It has been found that small plastic pieces which have been moulded to provide a large open surface area are suitable for this purpose.  
         [0158]     The column and canisters are mounted in a treatment tank/module generally designated  120  in  FIG. 11  but shown more clearly in terms of arrangement of conduits in  FIG. 8 . In this regard, the containers  85  are mounted concentrically with an air conduit  101 . The air conduit is provided with outlet holes  102  arranged to allow air fed through the air conduit to flow into the neck  89  of the middle canister and hence to flow upwardly so that the air permeates through the bottom of the upper canister and through the media contained therein. A seal  104  seals off the top of the air conduit by making a seal with the water conduit  103  located concentrically within the air conduit.  
         [0159]     The water conduit  103  is arranged so that it directs water to the sprinkler assembly  105  sitting atop the cartridge  80 .  
         [0160]     The sprinkler assembly includes an outer wall  106  which is spaced from, and extends around the sprinkler  108  mounted on the water conduit.  
         [0161]     The outer wall extends to a height greater than the sprinkler head to prevent splashing and is provided with a sludge trap  109  to catch sludge falling out of the sprinkler head thus preventing it from entering the upper canister.  
         [0162]     Referring to  FIG. 11 , the cartridges  80  are located in a moulded treatment tank which includes cartridge casings for snugly receiving the three cartridges and ducting for the various air and water inlets and outlets.  
         [0163]     In this regard, the treatment tank includes an air inlet line  110  directing air which has been pumped by the fan/pump  112  to the three air conduits  101 . Air exits out of the air outlet  118 .  
         [0164]     Similarly, water is supplied by an inlet pipe feeding the three water conduits  103 . The water which has been treated by trickling through the cartridges to exit through the bottom of the three columns  82  is allowed to flow out of the treatment tank  120  via an outlet line  116  to a reservoir or similar.  
         [0165]     Thus, the treatment tank  120  described with reference to  FIG. 11  may be substituted for the treatment tank  13  in the circuit which has been described with reference to  FIG. 7 .  
         [0166]     Whilst the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.  
         [0167]     It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.  
         [0168]     The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge in Australia.