WO1997002388A1

WO1997002388A1 - Water recycling system and method and devices therefor

Info

Publication number: WO1997002388A1
Application number: PCT/GB1996/001315
Authority: WO
Inventors: Shaun Alexander Hume
Original assignee: Triple Crown Securities Holdings Limited
Priority date: 1995-07-04
Filing date: 1996-06-03
Publication date: 1997-01-23
Also published as: GB9513670D0; EP0836661A1; ZA964602B; AU5842096A

Abstract

A water recycling system including a collection tank (8) and a header tank (22) to which water is pumped from the collection tank (8) through a supply pipe (18) by a pump (20). The supply pipe (18) terminates in a siphon loop so that water from the header tank (22) which has been disinfected by a disinfectant dispenser (42) siphons back down the supply pipe (18) to the collection tank (8). Disinfectant may be added to water before or as it is pumped between the tanks (8, 22) and disinfectant may be sprayed over system elements, such as a filter (9) as pumping occurs and when back-flow of disinfected water to the collection tank (8) occurs. The invention also relates to disinfectant dispensers and filters arranged to flush particles from their surfaces automatically.

Description

WATER RECYCLING SYSTEM AND METHOD AND DEVICES THEREFOR

The present invention relates to systems suitable for recycling water, such as wash water, in a domestic or industrial environment.

In the average household approximately one third of water used is for flushing toilet closets. There is no necessity for such water to come directly from the mains water supply and waste water from sinks and baths and rinse water from dish and clothes washing machines could be used for such a purpose. In view of the rapidly rising costs of treating and supplying mains water for domestic consumption, and the fact that many properties now have a metered water supply it would be particularly desirable to provide a means by which domestic wash water could be recycled and used for flushing water closets. In order to provide a system which is acceptable to consumers it is important that an uninterrupted supply of water can be provided for flushing purposes. The system moreover must require a minimum of operator intervention. In order to provide an uninterrupted supply it is desirable to provide for the supply of recycled water to be supplemented with mains water to cover situations in which the supply of recycled water is inadequate for some reason. This may occur for instance if a large temporary increase in the demand for flushing water occurs. The supplementing with mains water must be achieved without operator intervention. Water recycling systems which go some way towards meeting these requirements are described in GB Patents 2,249,121 and 2,235,719. Both of these systems employ a low level collection tank from which water is pumped to a high level header tank or break tank. Recycled water flows by gravity from the header tank to water closet cisterns when required and a supply of fresh water is provided, via a ball cock^' mounted inside the header tank, to top up the header tank when an inadequate quantity of recycled water is available. In order to prevent water in the header or collection tanks from producing an unpleasant smell it is desirable to provide the water they contain with a disinfecting agent. Where the header tank is situated in the roof void of a building, as is customary, and the collection tank is situated outside the building, it has been found that a higher concentration of disinfectant is required in the header tank than in the collection tank.

One object of the invention is to provide a recycling system which preferably provides such a differential in disinfectant concentration and yet which can operate with a minimum of operator intervention and employs few moving parts .

A further object of the invention is to provide a means of supplying disinfectant to various parts of a water recycling system in a reliable manner and with a minimum of operator intervention.

A still further object of the invention is to provide a method for achieving such disinfection of a water recycling system.

A further separate object of the invention is to provide an apparatus for adding disinfectant to a flow of water.

Thus according to the invention there is provided a water recycling system comprising a collection tank, a header tank situated above the collection tank and connected to it by a supply pipe, a pump arranged to pump water via the supply pipe from the collection tank to the header tank on demand and pump control means which deactivates the pump once water in the header tank has reached a pump cut-off level characterised in that the system further comprises disinfectant supply means arranged to supply disinfectant directly or indirectly to the header tank and which distributes the disinfectant throughout the system by means of transportation in the water in the system. Preferably disinfected water iε supplied to the collection tank by means of back-flow through the supply pipe to the collection tank.

With such a system only one supply of disinfectant needs to be provided which will, as a consequence of the back-flow, result in water in the collection tank and elements of the system associated with the collection tank being weakly disinfected.

The supply pipe can conveniently terminate in the header tank with a siphon loop or by being directed upwardly and with an outlet aperture below the cut-off level. Both of these configurations can be arranged to automatically allow back-flow from the header tank to occur only while the level of water in the header tank is above the outlet aperture of the supply pipe. Alternatively the back-flow may not include water from the header tank but be constituted mainly or entirely by water in the supply pipe.

Advantageous limitation of the quantity of disinfectant delivered to the collection tank occurs if between 2% and 20% and more preferably between 5% and 15% of the volume of water in the header tank, when back-flow commences, is returned to the collection tank.

In order to effectively disinfect elements of the system the system preferably includes nozzle means through which at least part of the back-flow or some other flow of disinfected water is sprayable to disinfect system elements . Preferably the system also includes means to spray a part of the water being pumped by the pump through the nozzle means as water is pumped to the header tank. This will increase the frequency at which disinfecting of the said system elements occurs .

The disinfectant supply meanε may conveniently doeε water with disinfectant as it is pumped to the header tank or supply it to the water once it has reached the header tank. Dosing water with disinfectant prior to reaching the header tank will mean that regular access to the header tank, for disinfectant replenishment purposes, can be avoided. Such access to the header tank may be inconvenient if it is situated in a roof void.

The disinfectant supply means may include a container in which dissolvable solid disinfectant material is accommodatable which material can progressively move down and become immersed in system water as lowermost disinfectant material dissolves and enters solution. With such an arrangement, a large supply of disinfectant material can be stored in the container with only the desired amount in contact with and dissolving in the water in the system.

When the disinfectant supply means is adapted to supply disinfectant directly to water in the header tank, it conveniently comprises a container in which dissolvable solid disinfectant material is accommodatable and a lower end of which is arranged to permit dissolved disinfectant to enter the water in the header tank. Such a supply means is simple to construct and may be easily adjusted to control the rate at which disinfectant is dispensed by simply moving the container up or down thereby immersing less or more solid disinfectant material respectively in the water. A portion, and preferably an adjustable portion, of water being pumped to the header tank may be arranged to pass through the container to enhance the dissolving of the solid disinfectant material.

Alternatively, the disinfectant supply means may comprise a dispenser in which dissolvable solid disinfectant material is accomodatable immersed in water, and having an outlet, the system further comprising means for supplying at least a portion of the water being pumped to the header tank to the dispenser such that water containing dissolved disinfectant passes through the outlet into the header tank by displacement. Such a supply means can conveniently be situated in the header tank, is simple to construct and facilitates the dosing of water in the header tank with a plurality of different disinfecting and dyeing agents .

A particularly convenient and easily controllable means of adjusting the amount of disinfectant supplied by the disinfectant supply means can be afforded by the provision of separation means, such as regulating valve means, arranged to at least temporarily separate a portion of the water being pumped to the header tank from a remainder of such water for the purposes of disinfectant entrainment.

The means described herein of supplying disinfectant to a flow of water or to a body of water such as that contained in the header tank, or to a flow of water such as that passing through the supply pipe are considered to constitute inventions independently of the other features described.

For hygiene reasons, it is desirable to prevent the system from supplying recycled water when adequate disinfecting is not possible and accordingly the system preferably includes deactivation means arranged to prevent actuation of the pump in such circumstances .

According to a further aspect of the invention there is provided a method of disinfecting a water recycling system comprising the steps of:

(a) collecting water in a collection tank;

(b) pumping water with a pump through a supply pipe to at least one other element of the system;

(c) supplying disinfectant with a disinfectant supply means to water supplied to the at least one other element; and

(d) distributing disinfectant throughout the system by means of transportation in the water in the system.

Preferably disinfected water is supplied to the collection tank by means of back-flow of water through the supply pipe to the collection tank. In a system such as that referred to above it has been found desirable to filter water which is to be recycled. A further independent object of the invention is accordingly to provide a filter arrangement which automatically flushes a filter provided for this purpose in an efficient manner and which also preferably automatically disinfects the filter. Such flushing and disinfecting will reduce the chance of the collection tank and its associated filter, which may be located remotely therefrom, producing an unpleasant smell as a result of the undesirable reproduction of micro-organisms .

Thus according to another aspect of the invention there is provided a filter arrangement for a water recycling system including a filter, an overflow passage with an inlet located substantially at an upper surface of the filter and discharge means for discharging water onto the filter at a location remote from the overflow passage inlet such that particles retained on the upper surface of the filter are flushed into the inlet and down the overflow passage. Even if the majority of water discharged onto the filter passes therethrough, some flushing flow over the surface will occur. According to this aspect of the invention there is also provided a method of automatically flushing residue from the surface of a filter.

In order to reduce the chance of particles becoming lodged on the surface of the filter and thereby prevented from being flushed down the overflow, the filter preferably includes an uppermost smooth surfaced filter screen having between 3 and 5 holes/cm². As foamed filter elements receive water more quickly if they contain relatively large voids yet trap particles more effectively if they contain small voids the screen is preferably underlain by an upper foam layer having between 8 and 10 pores/cm³ and a lower foa layer having between 35 and 40 pores/cm³.

In order to facilitate the connection of inlet and overflow pipework to the filter arrangement the discharge means may include baffle means for diverting water supplied to the filter arrangement to said location which is remote from the inlet of the overflow passage.

For the purposes of filter maintenance, the filter is preferably accommodated in a housing in which the filter can be lifted out of associated equipment.

When the filter arrangement is used in order to filter water supplied to the collection tank in the water recycling system described above, the system is preferably arranged to spray the filter with disinfected water each time water is supplied to the header tank. Such spraying will reduce micro-organism reproduction in the filter, flush particles off the surface of the filter and keep the filter moist. For certain foamed filter elements maximum throughput is dependent on the filter element being damp.

If the system is arranged so as to totally flood the filter when water in the collection tank is at a maximum desired level, the surface flushing of the filter will be enhanced and some back-flushing of the filter will occur as water discharged onto the filter surges through and returns upwardly to flow over its upper surface and into the overflow passage. Back-flushing will be still further enhanced if water is discharged onto peripheral regions of the filter. Such discharge also preferably occurs close to an upper surface of the filter. Preferably within 30 mm and more preferably within 15 mm.

So as to achieve the aforementioned flooding of the filter when the filter is situated outside collection tank, valve means are preferably provided to prevent water passing from the filter arrangement into the collection tank when water therein has reached the maximum desired level so that water will build up towards and eventually submerge the filter.

The inventions will now be described by way of example only with reference to the accompanying Figures in which: Figure 1 shows a schematic layout of a water recycling system according to the invention. Figure 2 shows a vertical cross section of the collection tank included in Figure 1. Figure 3 shows a detailed vertical cross section through an upper region of the tank shown in Figure 2 with water entering the tank. Figure 4 is a cross section on the line 44 of an upper portion of the tank shown in Figure

3. Figure 5 is a similar view to Figure 3 showing spraying of the filter. Figure 6 is a similar view to Figure 3 showing back-flushing of the filter. Figures 7 to 10 show cross sections of the header tank illustrated in Figure 1 at different stages of the header tank replenishment cycle. Figure 11 shows a schematic part sectioned view of a modified disinfectant dispenser and float valve arrangement. Figure 12 is a similar view to Figure 11 with the disinfectant dispenser almost empty. Figure 13 shows a schematic layout of an alternative water recycling system according to the invention. Figure 14 shows a schematic layout of a further water recycling system according to the invention. Figures 15 and 16 show the system of Figure 14 in in different stages of the recycling process . Figure 17 shows a part schematic vertical cross- section of the disinfectant dispenser used in the system shown in Figures 14 to 16. Figures 18 and 19 show diagrammatic vertical cross- section of the dispenser shown in Figure 17 at different stages of the recycling process . Figure 20 shows a part schematic layout of a further water recycling system according to the invention. Figures 21 and 22 show details of an alternative filter arrangement for use in the collection tank shown in Figures 1 and 13. Figure 23 shows an alternative filter arrangement for use in the system shown in Figure 14. In the accompanying Figures like numerals have been employed throughout to designate equivalent parts.

The system shown in Figure 1 includes a collection tank 8 into which waste water 1 from a bath 2 and a sink 4 flows via waste pipes 6 and rainwater from guttering 10 flows via a downpipe 12. Water enters the collection tank 8 through a filter 9 situated in an upper region of the collection tank. Should water in the collection tank rise to a level above the upper end of an overflow pipe 14 it overflows down the overflow pipe 14 into a drain 16. Water from the collection tank 8 is supplied by a pump 20, situated at the bottom of the collection tank 8, via a supply pipe 18, to a header tank 22 located in an elevated position. The pump 20 is actuated by a control system including a float switch 13 situated in the header tank 22 as a result of water in the header tank 22 falling to a pump cut-in level 30 as shown in Figure 10. The pump 20 continues to operate until the water in the header tank 22 reaches the pump cut-off level 31 shown in Figure 7 which is slightly above the downwardly directed end 34 of the supply pipe 18. At this point the float switch 13 causes deactivation of the pump. Once the pump has stopped, an upward loop 36 of the supply pipe 18 allows 12% of the contents of the header tank to siphon back into the collection tank 8, ie until water in the header tank 22 has reached the siphoned level 32 shown by a dotted line in Figure 7. At this point air enters the upward loop 36 and siphoning ceases. The supply pipe 18 may alternatively enter the header tank below the siphoned level 32 and end with an upwardly directed section terminating at the siphoned level 32. With such an arrangement, back-flow down to level 32 will occur by water simply flowing down into the supply pipe 18 rather than being siphoned. Should an adequate supply of water from the collection tank not be available, the water in the header tank will fall to the mains activation level 38 shown in Figure 8. As a result, the ball 25 of the ball valve 24 falls, thus permitting fresh water 40 to enter the header tank from a mains supply 26. Fresh water is supplied until the level in the header tank reaches a mains cut-off level 35 shown in Figure 9 just below the pump cut-in level 30. At this point the ball 25 rises and causes the ball valve 24 to cut off the supply of fresh water.

A collection tank slow drain valve 21 in the overflow pipe 14 is provided close to the base of the collection tank 8 in order to permit water in the tank to drain away slowly. The valve 21 is set so as to permit the entire contents of the collection tank to drain away in between 2 and 4 days. This will limit the maximum time for which the same water can reside in the collection tank. Other suitable drain means may be provided.

A disinfectant dispenser 42 comprising an open bottom tube 44 is mounted on a wall of the header tank so as to be vertically adjustable. A grille 46 near a lower end of the tube 44 supports tablets 48 or granules of disinfectant material such as C89 produced by Lever Brothers Pic which will slowly dissolve in the water. As the lowermost tablet dissolves those above it move downwardly and by adjusting the vertical position of the dispenser the surface area of the disinfectant tablets and hence the rate of supply of disinfectant to the header tank can be controlled. A skirt 50 extending below the grille 46 to a point also below the mains activation level 38 will prevent contact of the ambient air in the region of the header tank coming into contact with the disinfectant tablets 48 thus avoiding a strong smell of disinfectant being produced.

Disinfectant may alternatively be delivered to the header tank by dosing the recycled water with disinfectant as it is pumped from the collection tank. This may conveniently be achieved by providing a small reservoir of liquid disinfectant such as that marketed under the trade name Domestos, produced by Lever Brothers Pic, and connecting the reservoir to a venturi entrainment arrangement which acts to automatically draw the liquid disinfectant into the flow of water whenever a flow in the supply pipe 18 towards the header tank 22 occurs.

The presence of disinfectant in the header tank 22 will mean that when back-flow into the collection tank 8 occurs a small amount of disinfectant will be delivered to it. As only 12% of the volume of water in the header tank is returned to the collection tank and as the collection tank will be far larger than the header tank, the concentration of disinfectant established in the collection tank will be significantly lower than that in the header tank. The concentration of disinfectant required in a collection tank which is situated outside a building has been found to be lower than that required in an interiorly located header tank due to the natural ventilation occurring outside.

The filter 9 is accommodated within a closed compartment 52 in an upper region of the collection tank 8 and is supported by an apertured support member 54. A foam filter element 55 having 35-45 pores/cm³ is overlain by a filter tray or screen 53 having a smooth upper surface and 3-5 pores/cm². The overflow pipe 14 or overflow passage has an upper end 56 which is substantially at the same level as the upper surface of the filter tray 53. The down pipe 12 and the waste pipe 6 both terminate approximately 6 mm above the surface of the filter tray. This arrangement provides a filter which will back-flush itself under certain conditions as described below.

When demand for recycled water roughly equals the supply available, the level of water 58a in the collection tank 8 will be below the filter 9, for example at the level shown in figure 3. Water entering the tank through pipes 6 and 12 will pass through the filter tray 53 which will collect large particles and then through the foam element 55 which will trap smaller particles. If the rate of supply of water rises above the demand, the water level in the tank 8 will rise to the level 58b, slightly above the top of the filter tray 53, as shown in Figure 6, at which point water will start to flow down the overflow pipe 14. Some water leaving the pipes 6 and 12 will flow across the smooth top of the filter tray 53 causing the larger particles retained there to be washed down the overflow pipe 14, and some of the water will surge downwards through the foam element and return upwardly providing a filter back-washing effect (as indicated by the arrows in Figure 6) and then pass down the overflow pipe 14. This back- washing effect is enhanced by (a) the positioning of the pipes 6 and 12 at marginal regions of the filter 9, (b) the termination of these pipes close to the upper surface of the filter and (c) the positioning of the overflow pipe 14 in a central region of the filter.

As some particles will inevitably remain trapped in the foam element 55 and as it is possible that the water in the collection tank may not rise to the higher level 58b and effect filter flushing and back-washing for extended^' periods of time, it has been found desirable to periodically flush the filter with a disinfecting solution. When disinfectant has been supplied to the collection tank, for example using one of the methods described above, a convenient way to automatically disinfect the filter is to arrange for a proportion of the water pumped by the pump 20 to be diverted to one or more spray nozzles 60. A T- junction 62 connects a branch pipe 64 to the supply pipe 18, the distal end of which branch pipe is located in the filter compartment 52 which is substantially enclosed. The spray nozzle 60 has a threaded adjustment means (not shown) which permits the quantity of disinfected water sprayed into the filter compartment 52 each time the pump 20 recharges the header tank 22 to be regulated. The one or more nozzles are arranged to wash large particles retained on the filter tray 53 down the overflow pipe 14, disinfect all parts of the filter compartment and foam element 56 and keep the foam element moist, which for certain filter materials is advantageous. This operation will occur automatically and accordingly operator intervention is kept to a minimum.

If disinfectant is supplied to the water between the pump 20 and the T-junction 62 the concentration of disinfectant supplied to the nozzle 60 will be the same as that in the water being supplied to the header tank 22. This will provide more efficient disinfecting of the filter 9 than if the weaker concentration of disinfectant present in the water in the collection tank 8 is used.

With the header tank arrangement shown in Figures 7 to 10 the system will continue to supply recycled water regardless of whether any disinfectant is being supplied to the water being recycled. The disinfectant used may include a colouring agent so that a user will be alerted to the absence of disinfectant by the absence of colouration. In certain circumstance however it may be considered preferable to prevent recycled water from being supplied to water closet systems when the supply of disinfectant material has been exhausted. Figures 11 and 12 show a modified float switch 15 and disinfectant dispenser 43 which will cause the recycling system to supply only unused mains water once the supply of disinfectant in the dispenser has become nearly exhausted.

The header tank shown in Figure 8 includes a drip feed valve 51 which is located just above the mains actuation level 38 which acts to slowly leak the contents of the header tank 22, to the level of the valve 51, down the supply pipe 18. This will ensure that, even if the system is not used, periodically a pumping cycle will occur thus disinfecting the system.

The modified float switch 15 shown in Figures 11 and 12 includes an arm 66 which is pivotable about a spindle 68. A counterweight 70 depends from one end of the arm 66 and a rod 72, on which a float 74 is supported, depends from the opposite end of the arm 66. A weighted collar 76 slidably engages the rod 72 and is connected by a flexible tension member 78, for example a cord or thin metal cable, to a weight 80 which rests on the uppermost tablet 49 of disinfectant material. The tension member 78 is routed over two pulleys 82 mounted on a frame 84 attached to a side of the float switch 15.

When the disinfectant dispenser is charged with tablets 48, as shown in Figure 11, the weight 80 is sufficiently high that the collar 76 will not come into contact with the arm 66 even when the water level in the header tank 22 falls to the pump cut-in level 30. At thiε point the arm will adopt the position shown in broken lines 67 in Figure 11 and the float switch 15 will accordingly actuate the pump 20 in order that recycled water will be pumped from the collection tank 8 to the header tank 22.

When only one tablet 86 of disinfectant material is left in the dispenser 43 however, as shown in Figure 12, the weight 80 falls to such an extent that the tension member 78 pulls the collar 76 into the position shown in Figure 12. This in turn prevents the arm 66 from adopting the position 67 shown in broken lines in Figure 11 regardless of whether the water level in the header tank 22 falls to the pump cut-in level 30. Accordingly the pump 20 will not be actuated and as demand for water from the header tank 22 continues the water eventually falls to the mains actuation level 38 (shown in Figure 8) at which point the ball 25 falls causing mains water to enter the header tank via the ball valve 24. Demand for water from the header tank will be satisfied by the mains supply 26 until the disinfectant dispenser 43 is resupplied with disinfectant tablets so that the collar 76 can fall sufficiently to permit the float switch 15 to cause actuation of the pump 20. Such a modified float switch and its use as described above are considered to constitute separate inventions independently of other features described.

An alternative arrangement for routing water into the header tank 22 from the supply pipe 18 is shown in Figures 11 and 12 in which the water from the supply pipe 18 is routed into a lower region of the disinfectant dispenser 43. This arrangement results in the water entering the header tank swirling around the disinfectant dispenser. The process of disεolving the lowermost disinfectant tablet is thereby accelerated. A one way siphon bleed valve 65 is located in the upward loop 36 of the supply pipe 18 at the siphoned level 32 (see Figure 7) which prevents water leaving the pipe 18 but allows air to enter the pipe and so terminate back siphoning to the collection tank 8. One or more orifices 69 containing plugs may be provided adjacent the siphon bleed valve. By exchanging the siphon bleed valve with a plug from a higher orifice the siphoned level can be adjusted which will result in a greater surface of one or more disinfectant tablets being submerged. This will result in water in the header tank being disinfected to a greater extent, and less water being siphoned back to the collection tank.

Figure 13 shows, in a schematic form, an alternative water recycling system in accordance with the invention. Like parts are indicated by like numerals and the only significant difference from the system described with reference to Figures 1 to 12 is that entry of water to the collection tank 8 from the guttering is controlled by a rainwater ball valve 88.

Foul water drains 16 are not normally designed to cope with surface water run-off and accordingly it is necessary to prevent surface water from guttering 10 from entering the foul water drain 16. This would occur in the system shown in Figure 1 if water entered the collection tank 8 from the guttering 10 when the collection tank was full. The system shown in Figure 13 is accordingly supplied with a rainwater ball valve 88 which acts to prevent water entering the collection tank 8 via the rainwater supply pipe 90 when water in the collection tank 8 reaches the upper level 94 shown in Figure 13. Thereafter, further water pasεing down the downpipe 12 will back up the rainwater supply pipe 90, connecting the rainwater ball valve 88 to a tapping point 92, and then flow down the lower part of the downpipe 12 and into a surface water drain (not shown). When water in the collection tank 8 is at a lower level 98, such as that shown in broken lines in Figure 13, the rainwater ball valve 88 will be open and flow of water from the down pipe 12 into the collection tank 8 will be possible.

An alternative system is εhown in Figure 14 which is suitable for use in situations where it is not convenient to install a tall collection tank with a filter located at its upper end. Where appropriate, like numerals have been used to designate like parts described above.

The system shown in Figure 14 includes a low level collection tank 100 containing a pump 20 which is connected by a supply pipe 18 to one of three linked header tanks 102, 104 and 106. Part of the supply pipe 18 in the collection tank 100 is provided with a spray nozzle 108 and another part is connected to a disinfectant dispenser 112 described in detail below. The bath 2 and sink 4 are connected by a waste pipe 6 to a filter 114 which will be constituted in the same manner as that deεcribed with reference to Figure 21 and 22 below. The underside of the filter 114 is connected by a filter outlet pipe 116 to a ball valve 120 located in the collection tank. Thiε ball valve shuts off the filter outlet pipe 116 when waste water 1 in the collection tank rises to the full level 122 as shown in Figure 14. The waste pipe 6 and overflow pipe 118 lead to opposed sides of filter 114 adjacent its upper surface so that when water builds up in the filter outlet pipe, as a result of the ball valve 120 closing, the filter will eventually become immersed and thereafter further waste water reaching the filter 114 from the waste pipe 6 will flush particles from the upper surface of the filter down the overflow pipe 118 and thus into the drain 16. Automatic filter flushing will thus occur. A second spray nozzle 110 in fluid communication with the supply pipe 18 is positioned centrally above the filter 114.

The disinfectant dispenser 112 is shown in more detail in Figure 17. The dispenser includes a body 124 with a screw cap 126 and lower and upper branch pipes 128 and 130 which connect the supply pipe 18 with lower and upper regions respectively of the body 124. The lower branch pipe includes a one-way entry valve 132 and the upper branch pipe 130 includeε a one-way outlet valve 134 which iε regulatable by meanε of a knob 136. Regulation could alternatively be provided for the entry valve 132. The body 124 contains a stack of tablets 48 of disinfectant such as C89 tablets produced by Lever Brothers Pic.

The header tank 106 includes a float switch 13 connected by a wire 138 to the pump 20. Another header tank 102 includeε a mainε εupply 26 controlled by a ball valve 24. These items operate as described above with reference to the system shown on Figure 1 and their function will not accordingly be described in detail.

When water in the header tanks 102, 104 and 106 falls to the pump cut-in level 30 the pump 20 iε activated, provided there is sufficient water in the collection tank 100. As water is pumped up the supply pipe 18 two important things happen. Firstly, part of the water is sprayed through spray nozzles 108 and 110 which, as a result of being disinfected, diεinfect the upper region of the collection tank 100 and the filter 114. Secondly, a certain proportion of the flow is diverted into and out of the body 124 of the disinfectant dispenser 112 and in so doing becomes disinfected. Due to the one-way entry and exit valves 132 and 134 water will enter the body 124 via the lower branch pipe 128 and leave via the upper branch pipe 130. Due to pressuriεation, the level of water in the disinfectant dispenser will rise slightly as this procesε occurε aε indicated in Figure 18. By throttling the flow through the outlet valve 134 by meanε of the regulator knob 136 the proportion of water travelling up the εupply pipe which passeε into the disinfectant dispenser 112 can be reduced thus limiting the extent to which water εupplied to the header tankε iε diεinfected.

Once the water level in the header tankε haε reached the pump cut-off level 31, as shown in Figure 16, the float switch 13 cuts off the supply of power to the pump 20 which stops. Thereafter, the majority of the water in the supply pipe 18, which cannot pass back through the pump 20 because of a one-way valve 140 positioned at its outlet, is sprayed from the nozzles 108 and 110. Water 142 in the disinfectant dispenser above the level of the upper branch pipe 130 will flow through the exit valve 134, as indicated in Figure 19, and also flow down the supply pipe 18 and through the spray nozzles 108 and 110. Because the water flowing back down the supply pipe 18 contains disinfectant (a) the upper region of the collection tank and the filter are further disinfected and (b) the water 1 in the collection tank 100 is provided with a weak dose of disinfectant. Accordingly, when the above cycle is repeated the water sprayed from the spray nozzles 108 and 110, as the pump is operated, will provide the disinfecting action described above. In addition the system may be designed to back-siphon some of the disinfected water from the header tank 106 back down the supply pipe 18 to the spray nozzles 108 and 110.

Figure 20 shows an alternative syεtem according to one aεpect of the invention for supplying disinfectant, and possibly other additives such as dye, to the recycled water system of the type described with reference to Figures 1, 13 and 14. In the syεtem shown in Figure 20 an additive dispenser 144 situated in the header tank 106 is employed in place of the disinfectant dispensers 42 or 112 employed in the systems shown in Figures 1, 13 and 14. The collection of waste water in the proximity of the pump 20 will occur generally aε deεcribed above with reference to the other embodimentε and will accordingly not be deεcribed in detail .

When demand for recycled water from the header tank 106 results in the level of water therein falling to the pump cut-in level 30 the float 74 falls thus drawing the righthand end of the arm 66 of the float switch 15 down causing a signal to be sent via wire 138 and control circuit 146 to the pump 20. This causes the pump to pump waεte water paεt a one way valve 140 in the εupply pipe 118. Some of the waste water is diverted to spray nozzles 108 and 110 where, due to the presence of disinfectant in the water, effects disinfecting of the collection tank and/or filter. A secondary supply pipe 148 is branched from the main supply pipe 118 and the distribution of flow along these pipes is determined by the settings of a main supply regulator valve 150, situated in the main supply pipe 118 and a secondary supply regulator valve 152, situated in the secondary supply pipe 148. The secondary supply regulator valve 152 throttles the flow so that approximately 1% of the output of the pump is diverted up the secondary supply pipe.

The main supply pipe 118 terminates in the header tank 106 in an upward siphon loop 36 the lower end of which determines the siphoned level 32 in the header tank. A drain valve 73, situated at the bottom of the header tank 106, feeds into the main supply pipe 118 and is normally left very slightly open in order that if the system is left the recycled water will very slowly drain away. The header tank drain valve can be fully opened if there is a requirement to drain the header tank 106 for any reason.

The secondary supply pipe 148 terminates in the additive dispenser 144 which is situated in the header tank and will be described in detail below.

The additive dispenser 144 compriseε an open box¬ like body inεide which one or more barrierε 156 divide the body into compartments 158 which communicate via a gap at their lower ends. This permits piles of disinfectant tablet 48 and dye tablets 154 to be kept εeparate and neatly stacked and allows a selection of different typeε of tablet to be uεed to suit the prevailing requirements. An outlet pipe 160 permits water above a certain level in the additive dispenser 144 to drain into the header tank 106.

While disinfectant tablets 48 are available which will only deliver disinfectant to surrounding water up to a certain concentration, dye tablets 154 generally continue to dissolve until completely consumed. For this reason, one or more of the compartments includeε a platform 162 situated only slightly below an invert level of the outlet pipe 160. A dye table 154 resting on such a platform will only be partially immersed in water and as a consequence will only dissolve slowly.

The system is provided with a weight 80 on top of the disinfectant tablets 48 connected by a tension member 78 to a collar 76 which performs the same function as the similarly numbered parts shown in Figures 11 and 12.

As water is pumped up the supply pipe 118, a secondary flow 166 is diverted from the main flow 168 and passes up the secondary supply pipe 148 and into the additive dispenεer 144. Water containing diεinfectant and also possibly dye then circulates between the compartments 158 by passing through the gaps 164 under the barriers 156 and passes, under the action of diεplacement, out of the additive dispenser 144 via the outlet pipe 160 into the header tank. Once water in the header tank reaches a pump cut-off level above the siphoned level 32 the pump 20 is stopped and diεinfected water then siphons back from the header tank 144, down the main supply pipe 118 to the spray nozzles 108 and 110. Flow back through the pump 20 is prevented by the one way valve 140. Close juxtaposition of the outlet of the outlet pipe 160 and that of the main supply pipe 118 will increase the amount of disinfectant siphoned back down the main supply 118.

Figures 21 and 22 εhow detailε of an alternative filter arrangement which could advantageously be used in a tall collection tank 8 such as that shown in Figures 1, 2, 3 and 13 in order to facilitate maintenance of the filter.

The filter comprises two layers of reticulated polyether foam the upper layer having 8-10 pores/cm³ and occupying at leaεt 1500 cm³ and the lower layer having 35 to 45 pores/cm³ and occupying at least 3000 cm³. Such a filter construction has been found to be particularly suitable for a typical single family dwelling. The upper and lower foam layers have aligned central holes which accommodate upper and lower liner tubes 190 and 192 respectively. The upper end of the overflow pie 14 is a sliding fit inside the lower liner tube 190. Immediately above the upper foam layer 172 a smooth surfaced, flat, aluminum or stainless steel filter screen 176 is provided having 3-5 holes/cm². The foam layers 172 and 174 and the filter screen 176 are accommodated in a substantially cylindrical filter housing 170 at the upper end of which a housing lip 178 is provided which supports a complementary lip 180 of a baffle structure 182. The baffle εtructure 182 extends downwardly into the filter housing 170 and has peripherally situated holes 184 in its base 186 which only permit water entering the filter housing 170 through waεte pipe 6 and down pipe 12 to impinge on the filter εcreen 176 near itε outer edges .

When waste water 1 in the collection tank 8 is at the level shown in Figure 22 the majority of the water entering the filter housing 170 will pass through the filter screen 176 and the foam layers 172 and 174. A small amount of εurface flow 188 from peripheral regionε of the filter εcreen 176 down the overflow pipe 14 will occur however which will tend to flush items such as larger particles and hair caught on the filter screen 176 down the overflow pipe 14. The tendency for this to occur is enhanced by the fact that reticulated polyether foam tends to be less permeable when not completely saturated. When the surface of the waste water 1 in the collection tank 8 is at the level shown in Figure 21, i.e level with or slightly above the top of the overflow pipe, then the majority of water entering the filter housing will flush over the surface of the filter screen and pass into the overflow pipe 14. Some back-flushing of the filter will occur as described with reference to Figure 6.

When there is a requirement to gain accesε to the filter, once the pipes 6 and 12 have been moved to one side, the filter housing 170 is lifted, complete with the foam layers 172 and 174, the filter screen 176 and the baffle 182 from the top of the collection tank 8. Access to the filter is accordingly extremely easy.

It should be noted that the two part foam filter described may advantageously be used in any of the systemε deεcribed above.

In the εyεtem shown in Figure 14 the overflow pipe 118 takes water away from the filter 114 on the opposite side of the filter to that at which water is delivered by the waste pipe 6. Where this is not posεible, see for example the arrangement shown in Figure 23, a baffle 194 may be located above the filter screen 176 in the filter housing 196 which is positioned so as to deflect water to such a location on the filter screen 176 that it is constrained to pass across the filter screen 176 in order to reach the overflow pipe 118. This will ensure that the surface flushing effect described above occurε efficiently particularly when flow from the filter outlet pipe 116 is cut off and water has backed up to the level of the filter εcreen 176.

Claims

CLAIMS :

1. Water recycling system comprising a collection tank (8), a header tank (22, 106) situated above the collection tank (8) and connected to it by a supply pipe, a pump (20) arranged to pump water via the supply pipe (18) from the collection tank (8) to the header tank (22, 106) on demand and pump control means (17) which deactivates the pump (20) once water in the header tank (22, 106) has reached a pump cut-off level (31) characterised in that the εyεtem further includeε diεinfectant εupply means (42,43,112,144) arranged to supply disinfectant (48) directly or indirectly to the header tank (22, 106) and which distributes the disinfectant (48) throughout the system by means of transportation in the water in the system.

2. The system of claim 1 wherein disinfected water is supplied to the collection tank (8) by means of back-flow of water through the supply pipe (18) to the collection tank (8) .

3. The system of claim 2 wherein the back-flow of water includes a back-flow of a portion of the water in the header tank (22, 106).

4. The system of claim 3 wherein the portion of water constitutes between 2% and 20% of the volume of water in the header tank (22, 106) when back-flow commences.

5. The system of claim 2 or 3 wherein the back-flow is constituted by disinfected water in the supply pipe but not water from the collection tank (106).

6. The system of any preceding claim including nozzle means (60, 108, 110) through which water containing the disinfectant is sprayable to disinfect εyεtem elementε (9, 100 , 104 ) .

7. The εystem of any preceding claim including means to spray a part of the water being pumped by the pump (20) through nozzle means (60, 108, 110) as water iε pumped to the header tank (22, 106).

8. The εystem of any preceding claim wherein the disinfectant supply means (42, 43, 112, 144) includes a container in which dissolvable disinfectant material (48) is accommodatable, which material progressively moves down and becomeε immersed in syεtem water as lowermost disinfectant material dissolves and enters solution.

9. The system of any preceding claim wherein the disinfectant supply means (42, 144) is arranged to supply disinfectant directly to the header tank (22, 106).

10. The system of claim 9 wherein the disinfectant supply means compriεes a container in which dissolvable solid disinfectant material (48) is accommodatable and a lower end of which is arranged to permit disεolved disinfectant to enter water in the header tank (22).

11. The syεtem of claim 9 wherein the disinfectant supply means compriseε a dispenser (144) in which disεolvable εolid disinfectant material is accommodatable immersed in water and having an outlet (160), the system further comprising means (148, 152) for supplying at leaεt a portion (166) of the water being pumped to the header tank (106) to the diεpenser (144) such that water containing dissolved disinfectant passes through the outlet (160) into the header tank (106) by displacement.

12. The system of any one of claims 1 to 8 wherein the disinfectant εupply meanε (112) is arranged to supply disinfectant to the water as it is being pumped to the header tank (106).

13. The syεtem of any preceding claim wherein the diεinfectant supply meanε includeε εeparation means (128, 130, 150, 152, 148) arranged to at least temporarily separate a portion (166) of the water being pumped to the header tank (106) from a remainder of such water for the purpoεeε of diεinfectant entrainment.

14. The εyεtem of claim 13 wherein the εeparation meanε includes regulating valve means (128, 130, 150, 152) for controlling the separation of the portion (166) of water.

15. The syεtem of any preceding claim including deactivation means (13, 15) arranged to prevent actuation of the pump (20) when the diεinfectant εupply meanε (42, 144) haε an inadequate εupply of diεinfectant material (48).

16. A method of disinfecting a water recycling system comprising the stepε of :

(a) collecting water in a collection tank (8);

(b) pumping water with a pump (20) through a εupply pipe (18) to at leaεt one other element (22, 106) of the system;

(c) supplying disinfectant (48) with a disinfectant supply means (42, 43, 112, 144) to water supplied to the at least one other element (22, 106); and

(d) distributing disinfectant (48) throughout the system by means of transportation in the water in the εystem.

17. The method of claim 16 wherein disinfected water is supplied to the collection tank (8) by means of back-flow of water through the supply pipe (18) to the collection tank ( 8 ) .

18. A method of claim 16 or 17 applied to a system as claimed in any one of claims 1 to 15.

19. A filter arrangement for a water recycling system including a filter (9, 172, 174), an overflow passage (14) with an inlet located substantially at an upper surface of the filter and discharge means (6, 12, 182) for discharging water onto the filter at a location remote from the overflow paεεage inlet εuch that particles retained on the upper surface of the filter are flushed into the inlet and down the overflow passage (14).

20. The filter arrangement of claim 19 including a smooth surfaced filter screen (53, 176) situated above one or more reticulated foamed filter elements.

21. The filter arrangement of claim 20 wherein the filter screen has between 3 and 5 holes/cm².

22. The filter arrangement of claims 19, 20 or 21 wherein the discharge means includes baffle means (182, 194) which act to divert water supplied to the filter arrangement to said location remote from the inlet of the overflow passage (14).

23. The filter arrangement of any one of claims 19 to 22 accommodated in a housing (170) in which the filter can be lifted for the purposeε of filter maintenance.

24. The recycling εyεtem of any one of claims 1 to 15 in combination with a filter arrangement as claimed in any one of claims 19 to 23 wherein the filter arrangement filters water prior to or upon entering the collection tank (8).

25. The combination claimed in claim 24 wherein the filter arrangement (114) is situated outside the collection tank and valve means (120) are provided to prevent water passing from the filter arrangement into the collection tank ( 8) when water therein has reached a predetermined level .

26. An additive dispensing means (42, 43, 112, 144) comprising an open or cloεed container in which additive material (48) iε accommodatable and which includeε inlet means (46, 128, 148) and outlet means (46, 130, 160) arranged so that an inflow of liquid through the inlet means (46, 128, 148) results in displacement of liquid containing the additive out through the outlet means (46, 130, 160).