FIELD OF THE INVENTION

This invention is concerned with water processing, particularly although not exclusively with efficient backwashing of bodies of water.

BACKGROUND OF THE INVENTION

Progressive climate change is believed to be contributing to reduced rainfall and drought conditions in many regions around the world. Diminishing supplies of water in storage reservoirs and lowering of groundwater tables have lead to the imposition by local government authorities of water restrictions of varying severity upon domestic, commercial and agricultural water users.

While owners of swimming pools can contribute somewhat to water conservation by the use of swimming pool covers to reduce evaporative losses, one major water consuming feature of a swimming pool is the requirement to backwash the pool filtration system to clear the filter of contaminants removed from the pool water.

Other users of bodies of water which are subject to filtration and backwashing are also major water consumers, for example, waterparks, water cooling towers, waste water treatment plants, breweries, wine making facilities, aquaculture facilities and many others.

In a typical domestic swimming pool installation having a volumetric capacity of from 50,000 litres to 70,000 litres, a backwash and rinse cycle for a sand filter can consume between 1000 litres to 10,000 litres each week depending upon the. amount of contamination extracted from the pool water by the filter. Commercial pools can consume hundreds of thousands of litres of water per month. During the backwash and rinse cycles, water is drawn from the pool via the filter pump and then through the filter medium to a storm water drain or sewer drain as required by local government authorities. In some regions authorities do not allow waste outlets to be connected to any external drains.

There are potential disadvantages arising from the currently permitted methods of disposal of waste water from swimming pools and other facilities, either into a storm water drain or to a sewer line.

Generally speaking, for swimming pools employing an electrolytic chlorine generator, water in the pool is required to contain about 6000 ppm of sodium chloride (NaCI) for effective operation of the electrolytic chlorinator. Such a high salt content in the backwash and rinse water renders it unsuitable for collection and use for garden irrigation as in other grey water conservation systems due to the gradual accumulation of sodium chloride in the soil leading to degenerative salination of the soil. Ultimately this could give rise to a situation where authorities deem the pool owner's property as a contaminated site requiring expensive rehabilitation.

It would therefore be advantageous to provide an alternative backwashing system which alleviates the disadvantages associated with existing systems, or at least provide the consumer with a choice.

As used herein, the expression "swimming pool" is also intended to embrace the analogous use of spa baths, hot tubs, water parks and the like which are operated in a substantially identical manner to swimming pools. Similarly, the expression "backwash" is intended to include all water flows from a swimming pool filter, including backwash, rinse and bypass flows. SUMMARY OF THE INVENTION

According to one aspect of the invention, although it need not be the broadest aspect, there is provided a backwash system for a body of fluid comprising:

a filter including filter medium; and

a debris trap for capturing debris from the filter medium;

wherein the debris trap is fluidly connected to the filter.

In a further aspect of the invention, there is provided a backwash system for a body of fluid comprising:

a filter including filter medium; and

a debris trap for capturing debris from the filter medium;

wherein the debris trap is fluidly connected to the filter.

The fluid in the system of the invention can be water from a body of water such as a swimming pool, spa, waterpark, water cooling tower, waste water treatment plant, brewery, wine making facility, aquaculture facility or the like. Preferably the water is from a swimming pool or spa. The water used to remove the debris from the filter medium can be returned to the body of water from whence it originated after capture of the debris in the debris trap.

The filter medium is generally included in a filter already fitted to the filtration system of the body of water, such as a swimming pool or spa. The invention can be applied to any filter or filter medium, for example filters using media such as sand, diatomaceous earth, glass, zeolite, granular activated carbon, or filters such as bag filters, membrane filters, sieves or set of sieves or screens.

The body of water to which the invention is applicable can be any body of water which is filtered and backwashed on a regular basis, or irregularly, such as swimming pools, spas, water reservoirs for cooling towers and chemical/treatment plants.

The debris trap of the invention can be any debris trap that will adequately capture the debris in the water exiting the filter. The debris trap can be a membrane filter fitted into a flexible or rigid frame, a bag filter in a rigid or flexible frame, sand or glass filter cartridges fitted into a flexible or rigid frame. This debris trap can be either disposable after one or a limited number of uses, or manually cleanable in situ, or after removal from the filtration system.

The debris trap can be housed integral to the existing pump and filtration system of the body of water, for example included in the pump housing. Alternatively, the debris trap can be housed separately to the existing system and connected in fluid communication with the system.

The debris trap can comprise a single trap arrangement, or multiple arrangements, for example a number of filter bags in multiple housings in series. This configuration can be considered for more heavily soiled filtration medium. The debris trap is in fluid communication with the filter including filter medium. This allows fluid, preferably water, to flow through the filter medium and through or over the debris trap to capture debris from the filter medium. The fluid communication can be reversible attachment of an inlet of the debris trap to an outlet of the filter by any practicable means. For example, an existing backwash hose can be used to connect a debris trap inlet to the filter outlet.

In another aspect of the invention, the water exiting the debris trap can be directed to an inlet in the filter, enabling recirculation of the water and further debris removal. The substantially debris-free water can ultimately be returned the body of water after any number of recirculation passes through the debris trap and the filter medium. For this aspect of the invention, the debris trap can be connected to an inlet on the filter by any practicable means, including a hose attached to the debris trap outlet and filter inlet.

Preferably, the debris trap ultimately directs the water exiting the debris trap back to the body of water. This can be by any practicable means, such as a hose connected to the outlet of the debris trap. Attachment of the hose can be by any practicable means, including screw attachment, clamp attachment, and pressure attachment.

The flow of the fluid can be directed and controlled by valves in the system. Any practicable valve can be used to control the flow of fluid from the body of water to the filtration medium; from the filtration medium to the debris trap or back to the body of water.

The invention therefore provides a method and system for backwashing filter medium which eliminates wastage of water. The water used to backwash the filter medium is re-filtered in situ, and returned to the body of water. No water is lost or discarded in the method of the invention. Soil and public waterworks contamination, and water wastage is avoided. The invention is therefore highly advantageous, and economically and environmentally beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a backwash system according to an embodiment of the invention;

FIG. 2 is a front view showing conventional operation of a backwash system; and

FIG. 3 is a front view of a backwash system and method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The non-limiting example of the invention depicted in the Figures shows use of the system and method of the invention in a swimming pool environment.

Figure 1 shows a system (101) of the invention, comprising a pump housing (102) including debris trap (not visible) connected by piping (104) and (1 12) to a filter unit (105) with filter medium (not visible), which is connected by piping (106) to a sanitation unit (107). In this example, the debris trap is included in the pump housing (102). The debris trap can also be included in the system as a separate unit, which can be in communication with the system, or isolated therefrom.

Turning to Figure 2, conventional operation of the system (201) is depicted in filter mode, with direction of water movement shown as arrows in the piping (204), (206). Water from the swimming pool (208) enters the system through the pump (202), is pumped through piping (204) into the filter (205) where debris is removed from the water and accumulates in the filter medium. The water is directed through the filter medium (not visible), through piping (206) to the sanitation unit (207), and returned to the swimming pool (208).

Conventional backwashing would entail connection of a separate hose to an outlet on the filter housing containing the filter medium, reversal of the flow of water through the filter medium to force removal of the debris in the filter medium, and discarding the water including debris down a drain to sewage, or typically storm water drains, or onto surrounding ground.

Figure 3 shows the backwash method of the invention. Water from the swimming pool (308) enters the system through the pump (302). Further water entry is then arrested by closing valve (309). Water exiting from the system through pipe (306) is arrested by closing valve (310). The resultant loop recirculates water through the pump (302) and pipe (304), into the filter (305), through the filter medium in the reverse direction to conventional operation, forcing debris which has accumulated in the filter medium to exit the filter (305) at the outlet (311) with the water. The water containing the debris is then pumped through pipe (312), through the debris trap (not visible) in the pump housing (302) where substantially all or all of the debris is trapped by the debris trap.

In the aspect of the invention depicted in Figure 3, the water is thereafter redirected through the filter (305) and filter medium to effectively remove any remaining debris.

Ultimately (not shown), valve (310) is opened and the debris-free water is directed through pipe (306),. through the sanitation unit (307), and returned to the swimming pool.

The pump housing (302) can be opened and the debris trap removed, cleaned and returned to the housing, or replaced if disposable.

In this way, it is clear that the invention provides a much improved alternative backwash system and method, which is environmentally advantageous in many respects.

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features.

Throughout this specification, unless the context requires otherwise, the word "comprises", and variations such as "comprise" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not to the exclusion of any other integer or group of integers.