Abstract:
A rainwater treatment assembly ( 1 ) comprising a rainwater storage tank ( 2 ) and a treatment tank ( 3 ). Rainwater is delivered from the storage tank ( 3 ) where ozone is injected into it at regular time intervals. The ozone kills bacteria and oxidises transition metals.

Description:
[0001]    The present invention relates to a rainwater treatment process and assembly to provide potable water for dwellings, the process comprising gathering rainwater; delivering the rainwater to a storage tank; and treating the stored rainwater to render it suitable for drinking. 
       BACKGROUND OF THE INVENTION 
       [0002]    In this specification, the term “dwellings” is used to include not just simply domestic houses, but many other houses and buildings such as hotels, schools, retail outlets, commercial buildings such as nurseries and horticultural sites, and so on. 
         [0003]    It is well known to use rainwater for many uses, both domestically and industrially. In the domestic situation, such rainwater is used for toilet flushing, washing machines, garden watering and all other uses that do not require the rainwater to be potable. This is very often the case where houses are located in remote situations where water supply is problematical, to put it mildly, or is extremely expensive to provide. Similarly, in industrial situations, rainwater is often harvested to allow it to be used particularly for cleaning operations. 
         [0004]    For example, in a domestic situation, of the order of half of the water consumption does not require drinking quality water. Typical systems for utilising water for this include a water storage tank, usually mounted underground and connected via various filters and the like to the sources of the rainwater which are usually drainpipes connected to guttering on the building. It will be appreciated that generally the rainwater collection site, i.e. where the water storage tank is located, has to be below ground, as it has to be connected to the downpipes of the building. Although the tank may be sited above ground, it is generally sited underground to ensure it will receive a sufficient supply of rainwater, but also it needs to be underground or alternatively very heavily insulated to avoid freezing over during adverse climate conditions. However, as stated already, known systems do not provide potable water. Thus, there is still a need for the supply of suitable drinking water. 
         [0005]    There are other advantages in the use of rainwater that have long been appreciated. They prevent or reduce the likelihood that lime will be deposited on various parts of the water system as the water is “soft”. There are, however, other more important reasons for the use rainwater. As there is increased urbanisation, more and more rainwater is being delivered to drains and sewers where it then has to be recycled and, in many countries, is simply delivered to waste. The problem is that in urban areas, rainwater is mixed with other wastewater and this leads to having to provide very elaborate purification systems for this water which contains the rainwater. The rainwater itself is not very highly contaminated but because of being mixed with the other wastewater, it then requires considerable processing. 
         [0006]    Additionally, the collection of rainwater reduces the load on ground water drainage systems and is particularly advantageous during high load conditions, such as storms. 
       OBJECTS OF THE INVENTION 
       [0007]    The present invention is directed towards overcoming these problems by providing a process and assembly for purifying such rainwater to render it potable. 
       SUMMARY OF THE INVENTION 
       [0008]    According to the invention, there is provided a rainwater treatment process to provide potable water for dwellings comprising:
       gathering rainwater;   delivering the rainwater to a storage tank; and   treating the stored rainwater to render it suitable for drinking; characterised in that the process comprises treating the rainwater by:   delivering the rainwater to a separate treatment tank;   injecting ozone into the treatment tank at preset time intervals for preset time durations; and   on requiring water, the water is drawn off from the treatment tank and delivered to an ozone extraction device prior to delivery for use.       
 
         [0015]    The advantage of using ozone is that it is a very powerful oxidising agent, third among elements only to fluorine and atomic oxygen. Ozone can oxidise many organic compounds. It has been used commercially, in the treatment, for example, of wastewater. An ozone level of 0.04 ppm for four minutes has been shown to kill any bacteria, virus, mould and fungus in water. Ozone oxidises the transition metals to their higher oxidation state in which they usually form less soluble oxides that are then easy to separate by filtration. Iron, for example, is usually in the ferrous state when dissolved in water. When treated with ozone, iron yields ferric iron which is further oxidised in water to ferrum hydroxide. While it is accepted that the use of ozone for decades in water purification was known, it was not, we suggest, used in the manner of the present invention. 
         [0016]    In carrying out the process, the additional step may be performed, as the water is being drawn off, of filtering to remove contaminants oxidised by the ozone. 
         [0017]    In one process according to the invention, the steps are performed of:
       sensing the level of liquid in the treatment tank;   injecting ozone into the treatment tank when the level falls below a preset level;   after a preset time, delivering rainwater to the treatment tank from the storage tank until a desired water level is reached; and   continuing to inject ozone for a further preset time.       
 
         [0022]    The advantage of this is that ozone is only injected into the treatment tank as required. 
         [0023]    In another process according to the invention, the treated water is delivered from the treatment tank to a separate draw-off tank; the ozone is injected into the water in the draw-off tank at preset time intervals and for preset time durations; and on requiring water, the water is drawn-off from the draw-off tank. 
         [0024]    In this latter process of carrying out the invention, when the draw-off of water ceases, the draw-off tank may be topped up with water from the treatment tank and ozone is injected into the water in the draw-off tank. In this process, on the level of water in the draw-off tank falling below a preset level, the steps may be performed of:
       the draw-off of water is stopped;   the draw-off tank is filled with treated water from the treatment tank;   ozone is injected into the water for a preset time; and   the further draw-off of water can take place.       
 
         [0029]    The great advantage of having the separate tanks is that one can always be sure that when water is being drawn off, it has been adequately treated. It is not possible to draw off semi-treated water. Further, by injecting ozone into the treated water in the separate tank, it is possible to ensure that the correct level of sterility is maintained. 
         [0030]    In one process according to the invention, recirculation of the water is carried out by drawing the water from the treatment tank, injecting ozone as it is being drawn off from the tank and delivering the treated water back to the treatment tank. This further improves the sterilising of the water. 
         [0031]    In another way of carrying out the invention, on water being delivered to the treatment tank, the ozone is injected into the incoming water. 
         [0032]    In another process of carrying out the invention, the ozone is injected adjacent a bottom of the tank and also the water may be delivered adjacent a bottom of the tank. 
         [0033]    Further, the invention provides a rainwater treatment assembly comprising:
       a rainwater storage tank;   a rainwater treatment tank connected to the storage tank;   an ozone generator;   an ozone diffuser in the treatment tank connected to the ozone generator;   a controller, including a water level sensor in the treatment tank for draw-off of water from the storage tank and operation of the ozone generator,   a system outlet pipe for connection to a water supply system of a dwelling; and   a filter connected to the system outlet pipe, the filter comprising an ozone dissipater.       
 
         [0041]    This is a particularly suitable way of carrying out the invention. 
         [0042]    In another embodiment of the invention, the assembly comprises:
       a water inlet in the treatment tank adjacent a lowest part of the treatment tank;   a water feed pipe connected to the inlet; and   a venturii in the water feed pipe connected to the ozone generator.       
 
         [0046]    There may also be provided a draw-off tank intermediate the treatment tank and the system outlet pipe, the draw-off tank being connected to the ozone generator and the controller. The advantage of this separate draw-off tank is that it ensures no water is drawn off that is not adequately treated. 
         [0047]    For this latter assembly, the tank may comprise a composite tank divided into two separate storage sections to provide the draw-off and treatment tanks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]    The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: 
           [0049]      FIG. 1  is a view of a typical layout of a rainwater treating assembly according to the present invention, 
           [0050]      FIG. 2  is a diagrammatic view of the system of  FIG. 1 , 
           [0051]      FIG. 3  is a diagrammatic view of an alternative system according to the invention, 
           [0052]      FIG. 4  is a diagrammatic view of a still further system according to the invention, and 
           [0053]      FIG. 5  is a front view of the assembly illustrated in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0054]    Referring to the drawings and initially to  FIG. 1 , there is illustrated a rainwater assembly, indicated generally by the reference numeral  1 , comprising a rainwater storage tank  2  sited below ground and a treatment tank  3 . There is also illustrated a house  4  and an outhouse  5  housing the treatment tank  3 . The house  4  is illustrated with guttering  6  and various downpipes and other pipes  7  for collection of rainwater for delivery through a filter and calmed inlet  8  in the rainwater storage tank  2 . The house  4  is supplied with treated rainwater through piping  9  by a pump  10  while the rainwater treatment tank  3  is fed by piping  12  from the tank  2  by a pump  13 . The pump  13  is connected to a floating inlet  14 . An overflow pipe  15  of conventional construction is provided in the tank  2 . A mains top up valve  16 , controlled by a level switch  17 , is also provided. 
         [0055]    Referring now to  FIG. 2 , some of the details are removed and some of the parts are shown differently, however, they are, insofar as possible, identified by the same reference numerals. In this embodiment, there is illustrated a filter  20  delivering through a valve  21  operating a float  22 . The water treatment tank  3  has mounted therein an ozone diffuser  25  connected by a pipe  26  to an ozone generator  27  of conventional construction. The pump  10  is fed from the bottom of the treatment tank  3  through a system outlet pipe  30  incorporating an ozone removal filter  31 . The tank  3  has an inspection cover  35  and an ozone vent  36 . A control unit  40  is illustrated but is not shown connected to any of these equipment. 
         [0056]    In operation, when the level of water within the treatment tank  3  is sensed by the float  22  to have fallen below a certain level, the valve  21  is operated and water is pumped by the pump  13  through the filter  20  into the water treatment tank  3 . At the same time, the ozone gas generator  27  is operated to deliver ozone through the pipe  26  through the diffuser  25  and then up through the water in the water treatment tank  30 . The ozone is delivered for a preset time and is injected into the water treatment tank  3 , after the valve  5  is closed on the requisite amount of water being delivered to the water treatment tank  3 . The ozone gas generator  27  is used to deliver ozone at preset time intervals for preset durations of time. 
         [0057]    The precise arrangement described above is not essential for the efficient operation of the assembly. For example, the ozone removal filter  31  may be sited after the pump  10 . Also, many ozone extraction devices may be used. 
         [0058]    Referring to  FIG. 3 , there is illustrated an alternative construction of treatment tank, identified by the reference numeral  3 , in which parts similar to those described with reference to the previous drawings, are identified by the same reference numerals. In this embodiment, there is provided a flexible outlet pipe  37  connected to a float  38  and then the pump  10 . A valve, not shown, is also provided which is similar to the valve  21  of the previous embodiment. It will be further noted that the pump  13  delivers through the filter  20  as heretofore, but now to the bottom of the treatment tank  2  though an inlet  41  of a feed pipe  42  and housing a venturii  43  connected to the ozone generator  27 . The advantage of this particular arrangement is that the water entering the treatment tank  2  is subject to ozone treatment immediately as it enters the tank. Suitable water level control means for the valve is provided but not illustrated. 
         [0059]    Referring now to  FIGS. 4 and 5 , there is illustrated a still further construction of treatment tank, again identified by the reference numeral  3  and parts similar to those described with reference to the previous drawings are identified by the same reference numerals. In this embodiment, the treatment tank  3  is effectively the one tank divided to form two tanks, namely, into a treatment tank  40  and a draw-off tank  45  by a partition wall  46 . Essentially, there are two tanks, namely, a treatment tank  40  and the draw-off tank  45 . The treatment tank  40  and the ancillary equipment is connected in exactly the same manner as before, however, the treatment tank  40  is connected to the draw-off tank  45  through valves  47  and  48 , the valve  48  being connected to a float  49 . The pipe  26  extends from the ozone generator  27  through the partition  46  to an additional diffuser  50 . 
         [0060]    In operation, water is drawn off from the draw-off tank  45  in the same way as heretofore from the water treatment tank  3  and once the level of the water in the draw-off tank  45  falls below a preset level, water is delivered from the water treatment tank  40  into the draw-off tank  45 . 
         [0061]    There are many ways in which the apparatus according to the invention may be used. For example, the level of water in the treatment tank may be sensed and ozone can be injected into the treatment tank when the level falls below a preset level. Then, after that preset time, rainwater can be delivered to the treatment tank from the storage tank until the desired water level is attained. While the water is being delivered into the treatment tank, ozone can be delivered also into the treatment tank and indeed the injection of ozone can continue for a preset time after the water has been delivered into the treatment tank. 
         [0062]    When a separate draw-off tank is used, as described above with reference to  FIGS. 4 and 5 , the ozone can be injected into the water in the separate draw-off tank at preset time intervals and for a preset duration. Then, on requiring water, the water is drawn from the draw-off tank. When a draw-off tank is being used, it is possible to arrange such that when the draw-off of water ceases, the draw-off tank is topped up with water from the treatment tank and ozone is injected into the water in the draw-off tank. In this way, only fully treated water is used. Indeed, when the level of water of the draw-off tank falls below a preset water level, the draw-off of water can be stopped and the draw-off tank then filled with treated water from the treatment tank, ozone injected into the water in the draw-off tank for a preset time and then further draw-off water can take place. 
         [0063]    It is also envisaged that as water is being drawn off from either the treatment tank or the draw-off tank, ozone can be injected into the water as it is being drawn off. Indeed, it is envisaged that when water is being delivered to either the treatment tank or the draw-off tank, ozone can be injected into the water, as it is being delivered into the tank. 
         [0064]    It is envisaged that an ozone sensor may be provided to ensure that the ozone generator is operating correctly and that the rainwater is receiving adequate treatment. The ozone sensor may take the form of an ozone gas sensor in the ozone vent  36  pipeline. In the event that no ozone is found in the vent gas from the ozone vent  36 , the ozone gas sensor informs the control system of a failure of the ozone system. Alternatively, the ozone sensor may comprise a “wet” ozone sensor provided in one of the tanks, treatment and/or draw-off, or the pipework before the ozone removal filter so that the presence or lack thereof of ozone may be detected in the rainwater. On the wet ozone sensor detecting an ozone deficiency in the rainwater, the ozone sensor can inform the control system of a failure of the ozone system. 
         [0065]    Ideally, ozone is injected adjacent the bottom of either of the tanks. Ideally also, water is also delivered into the respective tanks adjacent the bottom of the tank. 
         [0066]    In the specification the terms “comprise, comprises, comprised and comprising” or any variation thereof and the terms “include, includes, included and including” or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa. 
         [0067]    The invention is not limited to the embodiment hereinbefore described, but may be varied in both construction and detail within the scope of the claims.