This application claims priority from Australian Provisional Patent Application No. 2009900871 filed on 27 February 2009, the contents of which are to be taken as incorporated herein by this reference.

Field of the Invention

The present invention relates generally to the filtration of water, and more particularly to a filtration system for grey water, and methods for filtering grey water using the system.

Background of the Invention

With an increasing world population, and concerns with drought in many countries, water has become a scarce, precious and expensive commodity. Unfortunately on a daily basis the water we use to bathe with, wash dishes, cars and clothes with, ends up as grey water that passes into our sewerage system never to be used again. Indeed, it has been shown that up to 61 % of the total waste water produced by an average household represents grey water.

It has also been shown that the total amount of grey water we generate in our homes on a daily basis amounts on average to 400 litres per day. Considering the large amount of grey water generated daily domestically, and an even greater amount generated commercially, being able to capture this grey water and purify it to a level for re-use, such as for flushing toilets and watering gardens (low-level purification) or for bathing and drinking (high-level purification), is highly desirable.

There are also instances where the capture and purification of grey water is a necessity and sanctioned by environmental standards. For example, grey water generated on water craft in many countries cannot simply be pumped into the ocean or river systems without first being treated and purified to an acceptable level.

Many processes have been developed in order to purify grey water to a desired level, and such systems have been adapted for domestic and the like applications. However, grey water invariably contains components such as food scraps, hair, dirt, oils, detergents, soaps, etc, which if not first removed, will inherently interfere with and ultimately inhibit these purification processes.

Attempts to remove components present in grey water prior to low- or high- level purification have commonly utilised a filter or sieve-like mechanism that traps the components as the grey water passes through. However, a problem with arrangements of this type is that the filter can quickly become blocked preventing efficient through-flow of the grey water and leading to the development of bacterial odours. The filters in systems of this type therefore require frequent cleaning or replacement for the purification process to continue in a productive and user-friendly manner.

Accordingly, the present invention provides a filtration system for grey water which overcomes the aforementioned problems of established water filtering systems.

Reference herein to a patent document or other matter which is given as prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country as at the priority date of any of the claims in this application.

Summary of the Invention

The inventor has recognised that the initial removal of components from grey water before subsequent low- and high-level purification procedures is important for the success of those procedures. Even if the grey water is simply intended to be re-used for purposes such as watering gardens and the like, removal of such components is ideal.

Accordingly, the present invention provides a filtration system for grey water, the system including:

(a) a housing for receiving and holding grey water from an external source;

(b) an inlet for allowing the grey water to enter the housing;

(c) at least two spaced-apart filters within the housing, each filter adapted to stop the flow of components present in the grey water as the grey water passes through each filter in turn; and

(d) an outlet for allowing grey water, which has passed through each filter in turn, to exit the housing.

In one embodiment, the housing of the filtration system of the present invention is in the form of a tank which includes a base, side panels and optionally a top panel. The housing may be of any shape or size depending on the situation it is to be used for, and the relevant space constraints applicable, if any. For example, if the filtration system is to be used on a water craft, such as a house boat, where space is at a premium, the housing may be located in the hull of the craft and will likely be elongate in shape and horizontally orientated. In other situations, such as for domestic installations, the housing can be of any appropriate size and of any shape, whether orientated in a vertical or horizontal manner.

The top of the housing may be in the form of a removable lid so that access to the filters and internal components of the system is possible, for example when replacement of components or cleaning of filters is required. Access to the housing from the top is also advantageous in that the presence of grey water in the housing will not limit access when required.

The housing may be constructed of any suitable material which can efficiently hold the grey water without seepage from the housing, and which can withstand the pressure that the contained volume of water will generate. Suitable materials may include rust-proof metals such as steel, plastics such as polyethylene, fibreglass, concrete, or galvanised sheet metal, provided that care is taken to avoid electrolytic action between dissimilar metals which may be used in the filtration system in toto. In one embodiment the housing is constructed of stainless steel.

The word "components" as used in the context of the present invention refers to matter naturally present in grey water. The term includes all matter which can, or has the potential to, interfere with subsequent water purification procedures when there is an intention to purify the grey water for re-use applications. Such components include, but are not limited to, hair, food scraps, dirt, leaves and other plant debris, oils, detergents, soaps and the like.

The meaning of the term "grey water", and the sources of such water, would be clearly understood by a person skilled in the art. For the purposes of example only, grey water can include water issuing from external sources such as hand basins, showers, sinks such as those in kitchens and laundries, washing machines, commercial car washes, rain and storm water, etc.

The housing of the filtration system of the present invention receives grey water from the aforementioned external sources via an inlet. In an embodiment of the invention in which the housing does not have a top panel or lid, the inlet may simply be the opening at the top of the housing into which the grey water falls. Alternatively, where the housing does include a top panel or lid, the inlet may be defined by a section of the top panel, for example a hole cut in the top panel through which the grey water enters. In this manner, in effect the inlet is formed within the housing.

In another embodiment, the inlet may be formed within a side panel of the housing, for example in the form of a hole cut in a side panel. In this instance, the inlet is preferably formed in an upper portion of the side panel of the housing. In this embodiment, and when the filtration system is to be utilised on a water craft, the inlet should be located in a position of the side panel low enough to clear the bottom of the deck beams of the craft. In this instance, the inlet will be positioned below a preset high level of grey water which is allowed to fill the housing.

The inlet should also be located at a position which allows the grey water to enter the housing before passing through each of the spaced-apart filters in turn as a result of the natural flow of the water through the system.

As indicated above, the filtration system of the present invention includes at least two spaced-apart filters within the housing. A "filter" as used herein is taken to mean a feature which allows grey water to flow through the housing but which stops the flow of components of a particular size that are present in the grey water.

In being spaced-apart, the filters are positioned relative to each other such that they can allow a flow of grey water between each filter. The filters are also positioned relative to each other such that grey water must pass through each filter in turn as it moves through the housing. Accordingly, grey water which has exited the housing would have passed through each and every one of the spaced-apart filters.

In one embodiment, the filters take the form of a metal plate which has a series of holes or pores present in the plate, the holes/pores being of a defined size and dimension. The holes/pores allow grey water to flow through the plate, and thereby through the housing, but stop the flow of components present in the grey water which are larger in size than the size of the holes/pores. In effect, the filter "retains" the components present in the grey water as the grey water passes through the filter.

The holes/pores according to this embodiment of the invention may be of any size or shape, e.g. round, rectangular, square, etc, provided that they stop the flow of components present in the grey water which are larger in size than the size of the holes/pores.

It will be appreciated that the filters may be in any form which allows grey water to flow through the filter, but which stops the flow of components of a particularly selected size which are present in the grey water. Accordingly, the filters may also be foamed-based or bead-based in nature, wherein the size of the holes/pores in the foam or beads dictates the size of the components retained.

In further embodiments, the system may include three, four, or more, spaced- apart filters within the housing. In one embodiment, each filter stops the flow of components of a different size to another filter as the grey water passes through the filters. In a further embodiment, at least one of the filters stops the flow of components which are about 100 μm or greater in size. In a preferred form, such a filter(s) is the last filter that the grey water passes through as the water moves through, and exits, the housing.

As used herein, the term "about" means approximately or nearly, and in the context of a numerical value or range set forth herein means ±10% of the numerical value or range recited or claimed.

In a further embodiment, the size of the components which are stopped becomes progressively smaller as the grey water passes through each filter in turn. That is, each successive filter in the housing (extending from the inlet to the outlet) retains smaller and smaller components. For example, the first filter that the grey water encounters as it enters and passes through the housing will only retain the largest of components such as food scraps and plant debris. The holes/pores of such a filter are generally between the range of about 4 mm to about 10 mm in size. For example, the holes/pores may be about 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or about 10 mm in size. The next filter that the grey water encounters will have holes/pores that are smaller again, such as between the range of about 1 mm to about 4 mm in size. For example, the holes/pores may be about 1 mm, 2 mm, 3 mm or about 4 mm in size.

In a preferred embodiment, as described above, the final filter that the water encounters as it moves through the housing will have holes/pores in the order of about 100 μm in size, thereby stopping the flow of components which are about 100 μm or greater in size. It would be clearly understood by a person skilled in the art that variations to the hole/pore sizes described above can be made for each filter. Grey water which has passed through all of the filters in turn is referred to hereinafter as "filtered" grey water.

In another embodiment of the invention, the filtration system further includes one or more baffles situated between each filter. The one or more baffles are impervious in composition, i.e. they do not contain holes or pores, and are typically made from materials such as galvanised sheet metal, stainless steel, plastic etc.

In a further embodiment, the filtration system of the present invention includes one or more baffles situated between the inlet and a first filter present in the housing. In this manner, upon entry of the grey water into the housing, the water will first encounter the one or more baffles before passing through any filter.

The purpose of the one or more baffles is to assist in the filtration process by retarding and/or stopping the flow of components which float on the surface of the grey water as the grey water makes its way through the housing. For example, the one or more baffles can retard and/or stop the flow of oil, which is present as a component of the grey water. Oil also has the potential to block the filters, and therefore the ability of the one or more baffles to retard and/or stop the flow of oil assists in the filtration process. Since the one or more baffles are impervious, they must be held within the housing in such a way that they do not prevent the passage of grey water through the housing. In one embodiment, the one or more baffles are held within the housing such that they allow grey water to flow underneath the baffles. Since oil, for example, present in the grey water will float to the surface of the grey water once it has entered the housing, grey water that proceeds to flow underneath the baffles will be devoid of oil, and in effect the one or more baffles retard and/or stop the flow of oil.

In one embodiment, the filters and baffles are located within the housing such that they extend entirely across the housing in a generally vertical position. Such an arrangement is typical for a system which is required for confined height spaces such as in the hull of a water craft. In such a space the housing of the system is often longer than it is higher and is therefore considered to be positioned in an end-to-end, or horizontal, orientation.

Having said that, as indicated above, the housing may take any form as the need and circumstances arise. Therefore in a further embodiment, the filters and baffles may be located within the housing such that they extend entirely across the housing in a generally horizontal position, i.e. the housing is positioned in a top-to-bottom, or vertical, orientation. In this manner, water will pass through the housing under the influence of gravity.

The filters and baffles can be held in position within the housing by any suitable means. In one embodiment, the filters and baffles are held permanently in position, for example by welding, riveting or otherwise gluing them in place within the housing. In another embodiment, the filters and baffles are held in position within the housing in a non-permanent manner such that they can be removed from the housing, for example for cleaning, replacing or otherwise performing routine maintenance when required. In this instance the filters and baffles can be retained by brackets built into the inside of the housing, thereby allowing the filters and baffles to be slideably placed in, or removed from, the housing. Preferably, the filters and baffles are held in position such that they do not move as grey water makes its way through the housing.

As indicated above, the filtration system of the present invention includes an outlet for allowing grey water, which has passed through each filter in turn, to exit the housing. By "outlet", it is meant a mechanism or means by which the water can be expelled from the housing. The inlet and outlet are generally positioned at opposing ends of the housing. In one embodiment, the outlet is positioned such that only grey water which has passed through each filter in turn can exit the housing via the outlet.

In one embodiment, the outlet includes a first pump which is situated external to the housing, the first pump arranged to expel grey water, which has passed through each filter in turn, from the housing. Any suitable pump may be used for this purpose provided it can effectively expel the filtered grey water to a location for re-use or further purification processes.

The first pump will ideally, but not essentially, have a small flow rate, such as in the order of about 20 to 25 litres per minute, be capable of a discharge pressure of up to about 50 p.s.i., and be capable of being run dry. In one embodiment, the first pump is a diaphragm pump.

In a further embodiment, the outlet further includes a hose in communication with the first pump, wherein the hose is situated in a portion of the housing that contains grey water which has passed through each filter in turn. By "communication" is meant that the hose and first pump interact with each other, either directly or indirectly, to enable the filtered grey water to exit the housing. Therefore the hose, being in contact with the water that has passed through each filter, will suck up and expel the filtered grey water from the housing when the first pump is activated. In one embodiment, and to enable maximum efficiency, the hose will be situated in a lower portion of the housing so that as much filtered grey water as possible can exit the housing through the action of the first pump.

In a further embodiment, the filtration system further includes a first sensor that is able to detect a preset high level of grey water present in the housing. The detection level is set by the user and can be altered according to the relevant circumstances and conditions for which the filtration system is being used.

In a still further embodiment, when the first sensor detects the preset high level of grey water present in the housing, the first pump is activated to allow the grey water, which has passed through each filter in turn, to exit the housing. In one embodiment, the first sensor is set to detect a high level of grey water that falls below the height of the filters so that water cannot exit the housing (via the outlet) without first passing through the filters.

In one embodiment, the filtration system includes a second sensor that detects a preset low level of grey water present in the housing. As with the first sensor, the detection level is set by the user and can be altered to suit required purposes. In a further embodiment, when the second sensor detects the preset low level of grey water present in the housing, the first pump is inactivated to stop the grey water, which has passed through each filter in turn, exiting the housing via the outlet. In effect, one purpose of the first and second sensors is to control co-ordinated removal of filtered grey water.

The first and second sensors can take a number of forms as would be known in the art, for example in the form of ball floats or electronic sensors. In one embodiment, the first and second sensors are in the form of respective electronic sensors. In such an embodiment, and as indicated above, one electronic sensor will have a provision to switch on the first pump when it detects the preset high level of grey water present in the housing, and the other electronic sensor will have a provision to switch off the first pump when it detects the preset low level of grey water present in the housing. In one embodiment, the inlet includes a valve (an inlet valve). The word "valve" as used herein refers to an opening and closing mechanism. Accordingly, the inlet valve prevents or allows the entry of grey water into the housing depending upon whether the valve is closed or open, respectively. For example, when the first sensor detects the preset high level of grey water present in the housing, it may be configured to not only activate the first pump (to allow grey water to exit the housing), but it may also be configured to close the inlet valve to prevent further grey water entering the housing. Grey water which can no longer enter the housing at this time may be diverted to a holding tank where it is stored until the inlet valve reopens.

In one embodiment of the filtration system of the present invention, the grey water which has passed through each filter in turn is subjected to one or more further purification steps. The one or more further purification steps are primarily for the purposes of achieving a level of purity specific for the intended end-use of the filtered grey water. For example, if the filtration system is being utilised on a water craft, then the water which has passed through the filtration system of the present invention will not be of a sufficient purity to expel into the river system. One or more further purification steps will be required to meet environmental standards. So too if the filtered grey water is to be used for bathing; however, in this instance the level of purity may not need to be as high.

In a further embodiment, the one or more further purification steps are performed after the grey water has exited the housing.

The one or more further purification steps would be known in the art and may include additional finer filtration procedures, such as through a submerged membrane, cartridge filter, sand filter or Diatomaceous Earth; ion filtration for the removal of nitrates, phosphorous, etc; and ultraviolet light treatments to destroy bacteria present in the "filtered" grey water. Elimination of nitrates, phosphates (and other fine particulates), bacteria (and other harmful contaminants) present in the grey water can also be addressed prior to the exiting of the grey water from the housing. For example in one embodiment, the filtration system of the present invention includes means for introducing an antimicrobial agent and/or a flocculation agent into the grey water which has entered the housing. Preferably, the antimicrobial agent and/or the flocculation agent are introduced as the grey water enters the housing, i.e. at the start of a new filling and filtering cycle.

In one embodiment, the antimicrobial agent and/or flocculation agent may be introduced by a single or separate pump which delivers a predetermined amount of the respective agent into the grey water present in the housing. The, or each, pump is preferably located external to the housing but is connected to the housing via a tube or the like. The antimicrobial agent and/or flocculation agent may enter the housing through the inlet, or may enter the housing via a separate entry point. Any suitable pump known in the art may be used for this purpose. For example, the pump may be a peristaltic pump.

Suitable antimicrobial agents would be known in the art. Collectively, antimicrobials kill or inhibit the growth of microorganisms such as bacteria, fungi, algae, or protozoa, and can destroy viruses. For the purposes of this invention, antimicrobial agents include agents that may be referred to in the art as antibacterial or antifungal agents. In one embodiment, the antimicrobial agent is chlorine, for example liquid chlorine. Preferably, the liquid chlorine is present at a concentration of between about 0.02 ml to about 1.0 ml per litre of grey water. For example, the liquid chlorine may be present at a concentration of about 0.2 ml to about 0.4 ml per litre.

Suitable flocculation agents would also be known in the art. For example, the flocculation agent may be selected from one or more of alum, aluminium chlorohydrate, aluminium sulfate, calcium oxide, calcium hydroxide, iron(ll) sulfate, iron(lll) chloride, sodium aluminate, sodium silicate, chitosan, isinglass, Moringa oleifera seeds, gelatin, Strychnos potatorum seeds, guar gum, and alginates. In one embodiment, the flocculation agent is alum. The concentration of alum which should be added to the grey water would be known in the art. Preferably, the alum is present in the grey water at a concentration of between about 0.01 % w/v to about 0.02% w/v.

In a further embodiment, the filtration system of the present invention further includes means for removing from the housing components which have been trapped or stopped by each filter and each baffle as the grey water passes through the housing. In one embodiment, the means for removing the components includes a second pump, a first valve and a second valve, wherein the second pump is in communication with the first valve, and the first valve is in communication with the second valve, and wherein the first valve and second valve allow the components to exit the housing when the second pump is activated.

The word "communication" as used here is taken to have the same meaning as described above. For example, the first valve and second pump, and the first and second valves, respectively, interact with each other, either directly or indirectly, to enable the components which have been stopped by the filters to exit the housing.

When the first and second valves are in an open position, the valves enable components of the grey water to exit the housing through the action of the second pump. When the first and second valves are in a closed position, the housing is effectively sealed such that grey water itself, as well as the components within the grey water, cannot exit the housing.

Given that the purpose of the second pump is to remove components of the grey water which have been stopped or trapped by the filters and baffles, whereas the purpose of the first pump is to remove filtered grey water, the type of pump used for each purpose may need to be different. For example, certain types of pumps, such as those containing valves, will quickly become blocked if they are used to remove retained components. Furthermore, the components may jamb open the valves of such pumps leading to additional problems, including failure of the system. Accordingly, in one embodiment the second pump is a screw pump which is not subject to the aforementioned problems of other pump types. Alternatively, any other type of pump which avoids these problems may also be used.

In one embodiment, the first valve is situated external to the housing. In a further embodiment, the second valve is situated in a portion of the housing which is underneath the filters and baffles. In this manner, when the second valve is opened, the components stopped by the filters and baffles can pass directly into and through the open second valve. The activation of the second pump effectively sucks the components through the open second valve, then through the open first valve, and ultimately out of the housing.

The types of valves which may be used would be known by a person skilled in the art. Such valves include, but are not limited to, knife, gate or ball valves.

In one embodiment, when the first pump is inactivated, i.e. when the second sensor detects the preset low level of grey water present in the housing, the second sensor activates the second pump and opens the first valve and second valve sequentially so as to allow the components to exit the housing.

Removal of the components in this automated fashion minimises user interaction, namely the need for regular manual cleaning of the filters and baffles to overcome and/or prevent blockages. This is because as the grey water exits the housing via the outlet, components which have been stopped or trapped by the filters and baffles move down the filters and baffles as the water line in the housing recedes. The components settle in a lower portion of the housing as a "sludge" for subsequent removal.

It is expected that over time, components which have been stopped or trapped by the filters and baffles, but which have not moved down the filters and baffles as the water line in the housing recedes, may build up to a point where they will need to be removed. This can be achieved for example by manual cleaning of the filters and baffles. However as indicated above, this process will only be required to be completed periodically rather than after each cycle of filtering.

However, to assist movement of stopped or trapped components down the filters and baffles, while maintaining limited or no manual handling requirements, the means for removing the components may include a system which automatically washes the components from the filters and baffles.

For example in one embodiment, after the filtered grey water has exited the housing, liquid (such as water) may be automatically sprayed onto the filters and baffles to promote movement of the stopped or trapped components into the component "sludge" present in the lower portion of the housing. The automatic spraying may be mediated by any suitable means, for example by spray heads which are mounted within or external to the housing.

In another embodiment, the automatic washing system may alternatively, or in addition, include brushes which contact and move down the filters and/or baffles, thereby moving the stopped or trapped components into the component "sludge".

Each filter and baffle present in the housing may be washed in this manner either after each cycle of filtration, or periodically such as once per day or week. Alternatively, only those filters with the smallest porosity in the housing are automatically washed, for example filters with holes/pores in the order of about 100 μm in size.

As described above, the first and second valves are opened sequentially, i.e. the first valve is opened before the second valve is opened. In this manner, any "unfiltered" grey water which is present in the housing, i.e. grey water which has not passed through any one or more of the filters and therefore still contains components, can first be removed from the housing (by the action of the second pump) prior to removal of the component "sludge" when the second valve is opened.

In a further embodiment, after a predetermined time, the second valve closes, effectively sealing the housing. A "predetermined time" as used in this context is a period of time which is sufficient for removal of the retained components through action of the second pump. The time can be set and adjusted by the user depending upon the capacity of the housing and the relative efficiency of the pump used.

In one embodiment, closing of the second valve may trigger opening of the inlet valve so as to allow more grey water to enter the housing to start a new filling and filtering cycle. The grey water may enter the housing either from the holding tank, and/or as it is generated.

Once the components have exited the housing they can then be transferred to an appropriate source depending on the nature of the environment for which the filtration system has been employed. For example, the components may be transferred to a separate dedicated containment for later removal. Alternatively, the components can pass into an established sewage system, as with the fate of "black" water in domestic settings. Finally, the components may be transferred to a sewage tank, such as that which is found on a water craft, for subsequent deposit at a pumping station along with any raw sewage collected on such craft.

It will be appreciated that the filtration system of the present invention need not rely on the preset high level of grey water being reached in the housing to initiate emptying of the grey water from the housing. For example, the filtration system may be configured to operate automatically after a preset time, for example 24 hour intervals, regardless of the amount of water in the housing. This will circumvent grey water being left in the housing for long periods thereby preventing stagnation. It would be clearly understood by the skilled addressee that having described a filtration system for grey water, the present invention also provides a method of filtering grey water, wherein the method comprises passing the grey water through a filtration system as described above.

Brief Description of the Figures

Having described the general concepts involved with the present invention, a preferred embodiment of a filtration system that is in accordance with the present invention will now be described. However, it is to be understood that the following description is not to limit the generality of the above description.

In the drawings:

Figure 1 is a schematic representation of the filtration system according to an embodiment of the present invention.

Figure 2 is a cross-section along plane A of the filtration system of Figure 1.

Figure 3 is a cross-section along plane B of the filtration system of Figure 1.

Description of the Embodiment Illustrated in the Drawings

The horizontal orientation of the filtration system 10 depicted in Figure 1 represents a typical arrangement suitable for use in water craft where the filtration system 10 is held in the hull of the craft and space is a premium. In this regard, the housing 1 1 of the filtration system 10 is elongate in shape in that the length of the housing 1 1 is generally greater than its height (but not essentially so as a generally square housing is also within the scope of the present invention), and the spaced-apart filters 13a, 13b, 13c, 13d are arranged generally vertically with reference to the orientation of the housing 1 1. It is to be made clear that the orientation of the filtration system 10 depicted in Figure 1 is for illustration purposes only. The filtration system of the present invention may equally be orientated such that the height of the housing 1 1 is generally greater than its length, and in this instance the housing 1 1 would take on an "upright" or "vertical" orientation compared with Figure 1. Furthermore, the filters 13a, 13b, 13c, 13d would be said to be arranged generally horizontally with reference to the orientation of the housing. Such an alternative orientation can be envisaged if the housing 1 1 of the filtration system 10 depicted in Figure 1 was rotated 90° anti-clockwise.

It will be appreciated that the housing 1 1 is in the form of a tank which includes a base 31 , side panels 22a and 22b (not all side panels are depicted in Figure 1 ) and a top panel 30. The tank defines a volume for receiving grey water. A side panel 22a of the housing 11 includes an inlet 12. Grey water from an external source enters the housing 1 1 through the inlet 12. The inlet 12 is located at a position in the housing 1 1 which allows the grey water to enter the housing 1 1 before passing through each of the filters 13a, 13b, 13c, 13d in turn. The grey water moves with a natural flow towards the first filter 13a. The natural flow is represented by arrow F in Figure 1.

The inlet 12 may include an inlet valve (not shown in the Figures) which prevents or allows the entry of grey water into the housing 1 1 through the inlet 12 depending on whether the valve is closed or open, respectively.

Although not depicted in Figure 1 , the housing 1 1 may also include one or more further inlets for allowing the entry of an antimicrobial agent and/or flocculation agent into the grey water present in the housing 1 1. Each agent may enter via the same further inlet, or may enter via their own separate further inlet. Alternatively, the agents may enter via inlet 12.

The housing 1 1 depicted in Figure 1 includes a top panel 30 in the form of a removable lid so that access to the filters 13a,13b,13c,13d and internal components of the system is made possible, for example when replacement of components or cleaning of filters 13a, 13b, 13c, 13d and/or baffles 23a,23b,23c,23d is required.

While the housing 1 1 depicted in Figure 1 is constructed of stainless steel, it would be appreciated that any material which can efficiently hold the grey water without seepage from the housing 11 , and which can withstand the pressure that the contained volume of water will generate, can be used.

The filtration system 10 depicted in Figure 1 includes a total of four filters 13a,13b,13c,13d which are spaced apart within the housing 1 1. In being spaced-apart, the filters 13a, 13b, 13c, 13d are positioned relative to each other such that they can allow a flow F of grey water between each filter 13a,13b,13c,13d. The filters 13a, 13b, 13c, 13d are also positioned relative to each other such that grey water must pass through each filter 13a, 13b, 13c, 13d in turn as it moves through the housing 1 1.

Each filter 13a, 13b, 13c, 13d takes the form of a metal plate which has a series of holes 24a,24b,24c,24d present in the plate that are of a predetermined size and dimension. The holes 24a,24b,24c,24d allow grey water to flow through the plate, and thereby through the housing 1 1 , but stop the flow of components present in the grey water which are larger in size than the size and dimension of the holes 24a,24b,24c,24d.

The size of the components which are stopped by the filters 13a, 13b, 13c, 13d becomes progressively smaller as the grey water passes through each filter 13a, 13b, 13c, 13d in turn. That is, each successive filter 13a, 13b, 13c, 13d in the housing (extending from the inlet 12 to the outlet 14) stops the passage of smaller and smaller components. Therefore, the size of the holes 24a in the first filter 13a that the grey water encounters as it enters and flows through the housing 1 1 are larger than the holes 24b in the second filter 13b. In this way, the first filter 13a that the grey water encounters will only retain the largest of components such as food scraps and plant debris. The final filter 13d that the water encounters as it moves through the housing 11 has the smallest holes 24d which are generally in the order of about 100 μm in size.

As seen in Figure 1 , the filtration system 10 also includes a series of baffles 23a,23b,23c,23d situated between the filters 13a,13b,13c,13d. The baffles 23a,23b,23c,23d are in the form of galvanised sheet metal plates and are therefore impervious in composition, i.e. they do not contain holes or pores.

Although not depicted in Figure 1 , it will be appreciated that the filtration system 10 may include one or more further baffles which are situated between the inlet 12 and the first filter 13a present in the housing 1 1. In this manner, upon entry of the grey water into the housing 1 1 , the water will encounter the one or more further baffles before passing through the first filter 13a.

The purpose of the one or more baffles 23a,23b,23c,23d is to assist in the filtration process by retarding and/or stopping the flow of components which float on the surface of the grey water as the grey water makes its way through the housing 1 1. For example, the one or more baffles 23a,23b,23c,23d can retard and/or stop the flow of oil, which is present as a component of the grey water. Oil also has the potential to block the filters 13a, 13b, 13c, 13d, and therefore the ability of the one or more baffles 23a,23b,23c,23d to retard and/or stop the flow of oil assists in the filtration process.

The baffles 23a,23b,23c,23d are held within the housing 11 in such a way that they allow grey water to pass underneath the baffles 23a,23b,23c,23d, thereby enabling the grey water to flow from one end of the housing 1 1 to the other. In this regard, and as shown in Figure 1 , the baffles 23a,23b,23c,23d are positioned in the housing 11 so as to define a gap (through which grey water can pass from one filter to the next) between the bottom of the baffles 23a,23b,23c,23d and a second valve 19. Figure 2 is a cross section (in plane A) of Figure 1 , and further illustrates how a gap 26a allows grey water to pass under a baffle 23a. In contrast, and as shown in Figure 1 , the terminal portion of each filter 13a, 13b, 13c, 13d does not define a similar gap. In fact the terminal portion 27a,27b,27c,27d of each filter 13a,13b,13c,13d which makes contact with the second valve 19 does not have holes, and is therefore impervious to grey water and grey water components. This is best seen in Figure 3 (plane B of Figure 1 ) which shows for example that there are no holes in the terminal portion 27b of the second filter 13b. In effect, this portion of the filtration system 10 is dammed in order to retain residual grey water and grey water components over the second valve 19.

Oil, for example, present in the grey water will float to the surface of the grey water once it has entered the housing 11 , and therefore grey water that proceeds to pass underneath the baffles 23a,23b,23c,23d will be devoid of oil. In effect the one or more baffles 23a,23b,23c,23d retard and/or stop the flow of oil through the housing 1 1.

Although Figure 1 depicts two baffles 23a,23b between the first filter 13a and the second 13b filter, the filtration system 10 may equally employ only one baffle between the first two filters 13a,13b. Any number of baffles can be employed between any of the filters depending on the expected oil content of the grey water.

As shown in Figure 1 , the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d are arranged generally vertically with reference to the orientation of the housing 1 1. The filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d occupy a first half of the housing 11 ; however, it would be understood that they can be arranged to occupy more or less of the housing 1 1 as desired.

The filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d are held in position within the housing 1 1 in a non-permanent manner such that they can be removed from the housing 11 , for example for cleaning, replacing or otherwise performing routine maintenance, when required. Each individual filter 13a, 13b, 13c, 13d and baffle 23a,23b,23c,23d is retained by brackets (not shown in the Figures) built into the inside of the housing 1 1 , thereby allowing each filter 13a, 13b, 13c, 13d and baffle 23a,23b,23c,23d to be slideably placed in, or removed from, the housing 11. In this manner, the filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d are held in position such that they do not move as grey water passes through them.

As grey water continues to enter the housing 1 1 and flows through the filters 13a, 13b, 13c, 13d, the water level within the housing 1 1 gradually rises as the volume of grey water contained within the housing 1 1 increases. To prevent the water level rising to a point beyond the capacity of the housing 1 1 , the filtration system 10 includes a first sensor 15 that is able to detect a preset high level of grey water present in the housing 1 1. The preset high level of grey water is represented in Figure 1 as dashed line X, and can be seen to be below the height of the filters 13a, 13b, 13c, 13d and below the inlet 12.

If grey water reaches the preset high level detection point X of first sensor 15, the first sensor 15 activates a first pump 14a to pump water out of the housing 1 1. The first pump 14a is located external to the housing 1 1 and is connected to a hose 14b which is situated in a lower portion of the housing 11 near the base 31 of the housing 1 1. The hose 14b is also situated in a region of the housing 1 1 which is located after the last filter 13d. Collectively, this ensures that as much filtered grey water as possible is pumped out of the housing 1 1 through the action of the first pump 14a.

The first pump 14a and the hose 14b collectively define an outlet 14 of the housing 11. As can be seen from Figure 1 , the inlet 12 and the outlet 14 are located at opposite ends of the housing 1 1.

As indicated above, the first sensor 15 may not only activate the first pump 14a, but it may also be configured to close the inlet valve (if present) of the inlet 12 to prevent further grey water entering the housing 1 1 during the emptying cycle. The filtration system 10 also includes a second sensor 16 which detects a preset low level of grey water present in the housing 11. The preset low level of grey water is represented in Figure 1 as dashed line Y. When the second sensor 16 detects the preset low level of grey water Y present in the housing 1 1 , the first pump 14a is inactivated to stop any more of the filtered grey water being pumped from the housing 1 1.

As the grey water exits the housing 1 1 , components which have been trapped or stopped by the filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d move or slide down the filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d as the grey water level recedes. The components typically settle as a component "sludge" underneath the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d in a lower portion of the housing 1 1. An indicative "sludge" level 28 is shown in Figure 1 , and for the embodiment depicted in Figure 1 , is equivalent to the preset low level of grey water Y.

The filtration system 10 further includes means for removing the trapped or stopped components, which have settled as a sludge, from the housing 11. The means for removing the components includes a second pump 17, a first valve 18, and the second valve 19. As can be seen in Figure 1 , the second valve 19 is situated in a portion of the housing 1 1 which is underneath the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d.

In the embodiment shown in Figure 1 , the second valve 19 includes an outer tube or cylinder, which defines the base 31 of the housing 1 1 , and an inner tube or cylinder. The outer tube or cylinder includes a series of apertures 19e,19f,19g,19h which have been cut into the second valve 19 at specific positions, i.e. at positions located directly below the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d. The inner tube or cylinder is sealed at one end 29, and includes a series of apertures 19a,19b,19c,19d cut into it at positions which align to the apertures 19e,19f,19g,19h in the outer tube or cylinder. The inner tube or cylinder fits with close tolerance to the inside surface of the outer tube or cylinder and can rotate within the outer tube or cylinder under the action of a valve motor 20. In effect, the apertures 19a,19b,19c,19d of the inner tube or cylinder are rotatable with respect to the apertures 19e,19f,19g,19h of the outer tube or cylinder. When the apertures 19a, 19b, 19c, 19d of the inner tube or cylinder are rotated by the valve motor 20 such that they align with the apertures 19e,19f,19g,19h of the outer tube or cylinder, the second valve 19 can be said to be in an open position.

When grey water present in the housing 1 1 has yet to reach the preset high level X, the inner tube or cylinder of the valve 19 is rotated to a position such that the apertures 19a, 19b, 19c, 19d in the inner tube or cylinder are not aligned with the apertures 19e,19f,19g,19h of the outer tube or cylinder. For example, the apertures 19a, 19b, 19c, 19d in the inner tube or cylinder may be rotated to a position of 180° with respect to the position of the apertures 19e,19f,19g,19h of the outer tube or cylinder. In this arrangement, the second valve 19 is effectively closed thereby preventing "unfiltered" grey water from passing into the second valve 19.

As shown in Figure 1 , the first valve 18 and the second valve 19 are directly connected to each other, and the second pump 17 is directly connected to the first valve 18. The second pump 17 and first valve 18 are located external to the housing 11.

In use, when the second sensor 16 detects the preset low level Y of grey water present in the housing 1 1 , it not only inactivates the first pump 14a, but it then activates the second pump 17, and opens the first valve 18 and second valve 19 sequentially so as to allow the components to exit the housing 1 1.

As described above, opening of the second valve 19 involves rotation of the inner tube or cylinder of the second valve 19 by the valve motor 20 so as to align the apertures 19a,19b,19c,19d of the inner tube or cylinder with the apertures 19e,19f,19g,19h of the outer tube or cylinder. In effect, the component sludge moves into the open second valve 19, passes through the open first valve 18, and exits the housing 1 1 under the sucking action of the activated second pump 17.

As indicated above, the first valve 18 and the second valve 19 are opened sequentially, i.e. the first valve 18 is opened before the second valve 19 is opened. In this manner, any "unfiltered" grey water which is present in the housing 11 , i.e. grey water which has not passed through any one or more of the filters 13a, 13b, 13c, 13d and therefore still contains components, can first be removed from the housing 11 (by the action of the second pump 17) prior to removal of the component "sludge" when the second valve 19 is opened.

At a time set by the user, the second valve 19 closes effectively sealing the housing 1 1 again. Closing of the second valve 19 can trigger opening of the inlet valve (if present) of the inlet 12. This allows more grey water to enter the housing 1 1 to start a new filling and filtering cycle. During this process, the first valve 18 remains open and the second pump 17 remains activated for a period of time set by the user so that the component "sludge" can continue to be removed from the housing 1 1 whilst more grey water enters the housing 1 1 through inlet 12.

In instances where trapped or stopped components from the filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d do not on their own settle as a sludge as the water level recedes upon emptying, further means for removing such components may be required. To reduce manual handling requirements, this may be achieved by a system which automatically washes the components from the filters 13a,13b,13c,13d and baffles 23a,23b,23c,23d. For example, a system which automatically sprays water onto the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d may be used to promote movement of the components into the component sludge. In order to achieve this, spray heads for example which are directed at the surface of the filters 13a, 13b, 13c, 13d and baffles 23a,23b,23c,23d may be mounted within or external to the housing 11. Typically, spray heads will be mounted downstream from the filter or filters with the smallest porosity, for example the last filter 13d shown in Figure 1.

An automatic washing system may alternatively, or in addition, include brushes which contact and move down the filters 13a, 13b, 13c, 13d and/or baffles 23a,23b,23c,23d, thereby moving the components into the component "sludge". Typically, such brushes will wash the filter or filters with the smallest porosity, for example the last filter 13d shown in Figure 1. It is to be noted that the automatic washing systems described above are not shown in the Figures.

The purification system 10 depicted in Figures provides advantages over other water filtering systems. For example, the purification system 10 allows the removal of components from grey water with no or minimal user interaction, thereby circumventing the need for regular manual cleaning of the filters and/or baffles to overcome and/or prevent blockages.

It should be noted that there may be other variations and modifications made to the configurations described herein, which will be apparent to those skilled in the art, and which do not depart from the scope and spirit of the present invention. Although the invention has been described in connection with a specific embodiment, it should be understood that the invention as claimed should not be unduly limited to the specific embodiment.