WO2008101276A1

WO2008101276A1 - Apparatus and method for removing contaminants from water

Info

Publication number: WO2008101276A1
Application number: PCT/AU2008/000213
Authority: WO
Inventors: William Peter Kennedy; Thomas Andrew Wood; Cheuk Yin Anthony Chan
Original assignee: Perpetual Water Pty Ltd
Current assignee: Perpetual Water Pty Ltd
Priority date: 2007-02-20
Filing date: 2008-02-20
Publication date: 2008-08-28
Anticipated expiration: 2009-08-20
Also published as: AU2008217555A1

Abstract

The invention relates to a method and apparatus for removing contaminants from waste water for subsequent use on gardens, lawns or for agricultural purposes. Waste water, especially laundry grey water, is contacted with a flocculent prior to use for irrigation. Purified water is safe for use in irrigation and does not adversely affect soil structure. The apparatus of the preferred embodiment is a portable and/or modular system capable of attaching to and receiving waste water directly from the outlet of a clothes washing machine.

Description

APPARATUS AND METHOD FOR REMOVING CONTAMINANTS FROM WATER

FIELD OF THE INVENTION

The invention relates to an apparatus and method for removing contaminants from waste water. In particular, the invention relates to an apparatus and method for recycling waste water for subsequent use on gardens, lawns or for agricultural purposes. More particularly, the invention relates to the purification of household waste water, especially household grey water, for irrigation purposes.

BACKGROUND OF THE INVENTION

A combination of drought and population growth has put enormous pressure on water authorities to constrain water consumption. As a result many households do not have access to sufficient water to maintain gardens and lawns which historically account for a large percentage of household water usage. A typical household generates a large volume of waste water, which has potential to be recycled for use in the garden, on lawns or for agricultural purposes. Recycled water intended for use in the garden, or similar applications, generally requires a lesser degree of purification than water that is intended for human or animal consumption.

Waste water from a household kitchen, bathroom or laundry is commonly termed "grey water", whereas waste water from a toilet or urinal is referred to as "back water". A household will produce grey water having different types of impurities and different concentrations of impurities, depending upon where the grey water originates. For example, grey water from a kitchen, bathroom or laundry, and from fixtures such as bath tubs, showers, hand basins, laundry tubs, spa baths, washing machines and kitchen sinks is often characterised by different impurities. In this regard, kitchen waste water is typically contaminated with a high content of fats and oils, which can be problematic in any purification system. Bathrooms produce grey water waste with a large variety of impurities including biological matter, soaps, toothpaste, shampoos, conditioners, hair dyes and cleaning chemicals. Laundry waste water has a high level of surfactants, salts and biological matter. In many studies people are concerned about the health impacts of direct exposure to recycled sewage (i.e. black water), however they are much less concerned with the reuse of recycled grey water particularly if it is collected by householders and used directly on garden or lawn areas. This has seen people directing untreated grey water effluent onto their gardens and carrying buckets from their showers and baths with little thought of the consequences for their health or the long term health of their soil. In addition, there is the risk that grey water run-off will mix with and contaminate natural watercourses or groundwater.

Often in the domestic situation it is not possible to separate grey water streams from different rooms, or to even collect the combination of all household grey water. In this regard, most houses built over the last 20 years are on a concrete floor slab with waste water pipes joined under the slab, making access to waste water from different rooms, or even a combination of waste water streams, extremely difficult, if not impossible. This inability to capture household grey water adds to the complexity of any purification system.

PCT/AU05/000568, which is an earlier application of the present applicant, discloses a water purification system that purifies grey water after is has entered the waste water drainage system of a household. As discussed above, PCT/AU05/000568 is not suitable for all households as installation requires access and modification of existing household plumbing. Whilst the purification process employed in PCT/AU05/000568 is suitable for treatment of combined grey water from a variety of sources within a household, including bathroom and laundry, this convenience adds to the maintenance, cost and complexity of the system, and accordingly it is unsuitable for many applications. In addition, PCT/AU05/000568 does not purify waste water specifically for use in irrigation, while averting damage to soil structure and possibly other adverse environmental consequences. In fact, water purified using the system of PCT/AU05/000568 is suitable for reuse in households generally, for example in laundries or for flushing toilets.

Accordingly, there is a need in the art for an improved grey water treatment system and apparatus that can easily collect and purify grey water so that is can be reused on gardens and lawns, or agriculturally, with no health or environmental consequences. The present invention attempts to substantially overcome the problems discussed above, or at the very least provide a useful alternative to known systems.

SUMMARY OF INVENTION

In one aspect the invention resides in a portable and/or modular apparatus allowing flexibility and variety in use for purifying waste water for subsequent use in irrigation, comprising an inlet which is capable of attaching directly to and receiving waste water from an outlet hose of a clothes washing machine; a waste water collection vessel; a first dosing chamber; and a purified water outlet.

The apparatus is of a size that is easily mobile and can be carried or wheeled and its use does not require permanent plumbing, or other fixing. The apparatus need not therefore be permanently positioned, but rather may be moved from site to site as required, much like other household appliances such as a garden mulchers, or washing machines, that may be retained by the householder if they move house.

Preferably, the first dosing container is a capable of dosing the collection vessel with flocculent. The apparatus preferably includes a pump capable of pumping waste water in the collection vessel through the first dosing chamber. The apparatus may further comprise a second dosing chamber capable of dosing water being treated with a conditioning agent. The conditioning agent is employed to balance or adjust Na⁺, Mg²⁺, Ca²⁺ or K⁺ cation concentration in the treated water.

Preferably, the collection vessel has a capacity of 200-500 litres and the apparatus treats 200-500 litres of waste water per cycle. Most preferably, the apparatus holds and treats approximately 250 litres of waste water per cycle.

Preferably, the inlet is capable of being reversibly connected to the outlet of a clothes washing machine, either front loader or top loader. Similarly, the purified water outlet is configured for reversible connection to an irrigation system. Most preferably, the irrigation is a subterranean irrigation system.

The apparatus typically includes a waste water outlet. Untreated water in the collection vessel can be dumped via the waste water outlet after a set period of time, for example about 24 hrs. Treated water stored in the collection vessel that is no longer required can also be dumped. Ideally, treated water is stored for about 7 to 14 days before being dumped. Preferably, the apparatus is programmed to dump any water in the collection vessel after a set interval of time.

Preferably, the apparatus includes a filter capable of removing solids from the purified water prior to use.

In another aspect the invention resides in a method of treating waste water for subsequent use in irrigation, comprising contacting waste water with the following: a) a flocculent; b) a conditioning and/or pH balancing agent; and removing floes from the treated water to produce purified water, wherein the purified water has a turbidity of at least 1 NTU.

The method seeks to purify waste water effluent to a degree that it is suitable for irrigation purposes in a sustainable way without adversely affecting soil structure. The method typically reduces the turbidity of waste water to above that considered suitable for drinking water. Preferably the NTU of purified water is between about 1 and 25 Nephelometric Turbidity Units (NTU), and most preferably between about 1 and 5 NTU. The SAR of the treated water is generally less than 3, with generally over 90 percent, and often over 99 percent, of phosphorous removed.

Preferably, the waste water is grey water. Most preferably, the waste water is laundry grey water. Even more preferably, the waste water is domestic laundry grey water treated for subsequent use in subterranean irrigation.

The method may include the step of contacting the waste water with a conditioning agent. Preferably, the conditioning agent is one or a combination of chemical agents that are added to the waste water to balance or adjust Na⁺, Mg²⁺, Ca²⁺ or K⁺ cation concentration. Preferably, the conditioning agent includes one or more of the following: magnesium hydroxide, magnesium carbonate, magnesium sulphate, calcium hydroxide (lime), calcium sulphate (gypsum), calcium carbonate and calcium hypochlorite. Most preferably, the conditioning agent includes magnesium carbonate. Even more preferably, the conditioning agent includes magnesium hydroxide liquid. When magnesium hydroxide liquid is 55% magnesium hydroxide liquid it is preferably applied at the rate of 0.19 +/- 0.03 mL/L. More preferably, it is applied at the rate of 0.19 +/- 0.01 mL/L.

The method may include the step of contacting the waste water with a pH adjusting or balancing agent. Preferably, the pH adjusting agent is magnesium carbonate applied at the rate of 0.21 +/- 0.04 grams/L. Most preferably, it is applied at the rate of 0.21 +/- 0.03 grams/L.

Preferably, the flocculent includes aluminium sulphate. Most preferably, the aluminium sulphate is liquid 8% Al₂O₃ and is added to the waste water at the rate of 0.2 mL/L to 2.0 mL/L. Most preferably, at the rate of 0.6 mL/L to 1.2 mL/L. Alternatively, the aluminium sulphate is solid 17.3% Al₂O₃ and is added at the rate of 0.10 grams/L to 2.00 grams/L. Most preferably, the rate of addition of solid Al₂O₃ is 0.6 grams/L to 1.0 grams/L.

Preferably, the method includes the step of contacting the waste water with a particulate filter. More preferably, the particulate filter is a depth filter. A pleated depth filter with a nominal rating below 0.5 μm is most preferred.

Preferably, the method of the invention is used in conjunction with the apparatus of the invention.

In a further aspect the invention resides in a system for treating laundry waste water comprising: a) determining if the waste water is generated by a front loading or top loading clothes washing machine; b) determining the type or brand of laundry detergent that has been used; and c) selecting an optimal treatment regime from a range of predetermined treatment regimes base upon a) and b).

In a still further aspect, the invention resides in self contained modular home appliance comprising: a) an inlet for direct attachment to the outlet of a clothes washing machine; b) a 200 to 300 litre waste water collection vessel; c) first and second dosing chambers; d) a purified water outlet; e) a waste water outlet; f) a least one waste water pump, and g) a computerized control panel.

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

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described in a non-limiting manner with respect to a preferred embodiment in which:-

FIG 1 shows a schematic of a water purification apparatus employing automatic liquid dosing of flocculent, conditioner and/or pH balancer according to a preferred embodiment of the invention.

FIG 2 shows a schematic of a water purification apparatus employing manual solid dosing of flocculent, conditioner and/or pH balancer according to a preferred embodiment of the invention.

FIG 3 graphs pH against aluminum sulphate dose (grams/L) for grey water samples from fourteen common top loader laundry detergents of Example 1.

FIG 4 graphs pH against aluminum sulphate dose (grams/L) for grey water samples from sixteen common front loader laundry detergents of Example 2.

FIG 5 depicts a grey water treatment apparatus according to a preferred embodiment of the invention.

FIG 6 depicts a typical installation for a grey water treatment apparatus according to a preferred embodiment of the invention.

FIG 7 depicts attachment of a grey water treatment apparatus according to a preferred embodiment of the invention to a waste water outlet and irrigation system. FIG 8 depicts a control panel for a grey water treatment apparatus according to a preferred embodiment of the invention.

FIG 9(a) and FIG 9(b) depicts an arrangement for adding grey water treatment agent(s) to a grey water treatment apparatus according to a preferred embodiment of the invention.

FIG 10 depicts a grey water treatment apparatus according to a preferred embodiment of the invention and including detail with respect to replacement of the filter cartridge.

FIG 11 depicts a grey water treatment apparatus according to a preferred embodiment of the invention and including detail with respect to replacement of the filter cartridge.

FIG 12 is a perspective view of a grey water storage vessel according to a preferred embodiment of the invention.

FIG 13 is a perspective view of a dosing chamber according to a preferred embodiment of the invention.

FIG 14 is a sectional view of a dosing chamber according to a preferred embodiment of the invention.

FIG 15 is an exploded perspective view of a dosing chamber according to a preferred embodiment of the invention.

FIG 16 is a perspective view of a plumbing connection according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Households generate a large volume of waste water that has the potential to be recycled for use in irrigating gardens and lawns, or for agricultural purposes including growing vegetables or fruit.

Household grey water has a large number of impurities, including biological matter, soaps and other surfactants, cleaning chemicals, salts and phosphates. The typical make-up of grey water will however often depend upon on where, or in what room, the grey water is produced. Laundry grey water is generally considered to be the dirtiest produced by households as it is high in salts and particulates, has a very high biological oxygen demand (BOD), is high in microorganisms and also has a high pH. Untreated grey water, especially laundry grey water, is therefore not generally suitable for use in irrigation as it has the potential to stunt the growth of many plants and degrade soil structure causing reduced infiltration, percolation and drainage. Moreover, the concentration of impurities in laundry grey water is dependent upon the particular laundry detergent used. For example, environmentally friendly detergents generally have a lower level of phosphorus than standard detergents. Grey water pH can also vary markedly depending upon the particular laundry detergent. The level of impurities in grey water is also affected by the type of washing machine employed. In this regard, top loading machines generally use more water and hence dirt and detergent impurities are more dilute, whereas front loaders produce grey water with a higher concentration of dirt and impurities.

Taking the above factors into account, the invention describes an apparatus and method for treating waste water effluent rendering it suitable for irrigation. Waste water treated according the invention has a low level of solids, bacteria and/or turbidity. The skilled addressee will appreciate that the invention could be employed in either a domestic or a commercial setting.

The method and apparatus of the invention is well suited to treating waste water for subsequent use in subterranean or subsurface irrigation for gardens, lawns or for agriculture. Waste water purified according to the invention may also be employed for surface irrigation, depending upon the specific regulatory requirements of different jurisdictions.

Flocculents, or coagulants, are chemicals that are used to promote flocculation by causing colloids and other suspended particles in liquids to aggregate, forming a floe. Flocculents are used in water treatment processes to improve the sedimentation or filterability of small particles, which would be difficult or impossible to remove by filtration alone.

Many flocculents are multivalent cations such as aluminium, iron, calcium or magnesium. These positively charged molecules interact with negatively charged particles and molecules to reduce the barriers to aggregation. In addition, many of these chemicals, under appropriate pH and other conditions, react with water to form insoluble hydroxides which, upon precipitating, link together to form long chains or meshes, physically trapping small particles into the larger floe. Flocculents also come in the form of long-chain polymers, such as modified polyacrylamides. Common flocculents include alum, aluminium chlorohydrate, aluminium sulphate, calcium oxide, iron (III) chloride, iron (II) sulphate, sodium aluminate, sodium silicate. Natural flocculents include Moringa oleifera seeds, papain, strychnos and isinglass. As some flocculents, such as alum and ferric chloride, have the added effect of adjusting the pH they may be particularly advantageous in inducing flocculation of waste water. Preferred flocculents according to the invention include alum in its various forms including A1₂(SO₄)₃ and KA1(SO₄)₂.12H₂O; and aluminium chloride, ferric chloride or ferric nitrate, mixtures thereof. Most preferable the flocculent for use in the invention is aluminium sulphate. When the aluminium sulphate is in solution, 8% Al₂O₃, the dosing range is preferably from 0.2 mL/L to 2.0 mL/L although the most preferred range is from 0.6 — 1.2 mL/L. When solid aluminium sulphate, 17.3% Al₂O₃, is used the dosing range is preferably from 0.10 grams/L to 2.00 grams/L although the most preferred range is 0.6 - 1.0 grams/L.

As used herein the term "conditioning agent" refers to one or more chemical agents that may be added to waste water to balance or adjust Na⁺, Mg²⁺, Ca²⁺ or K⁺ cation concentration prior to use. The conditioning agent according to the invention may be added to waste water undergoing treatment as a single unitary dose, comprising one or more distinct chemicals, or alternatively, may be added as multiple doses of one or more chemicals at different stages in the waste water treatment process.

Cation concentration is an important consideration where recycled waste water is intended for use on gardens, lawns or for agricultural purposes, as changes in the concentration and distribution of Na⁺, Mg²⁺, Ca²⁺ and K⁺ cations in soil has the potential to adversely affect soil condition. For example, in laundry grey water there is a high level OfNa⁺ ions that can have a detrimental effect on soil structure, potentially resulting in sodic soil, i.e.: soils with high levels of exchangeable sodium and low levels of total salts. According to the invention, the addition of one or more conditioning agents can address this issue. Preferred conditioning agents for adjusting cation concentration according to the present invention include magnesium hydroxide, magnesium carbonate, magnesium sulphate, calcium hydroxide (lime), calcium sulphate (gypsum), calcium carbonate and calcium hypochlorite. When magnesium hydroxide liquid, 55% magnesium hydroxide, is employed the effective range is generally 0.19 +/- 0.05 mL/L, most preferably 0.19 +/- 0.03 mL/L. When magnesium carbonate is used the effective range is generally 0.21+/- 0.06 grams/L, most preferably 0.21+/- 0.03 grams/L. When a combination of flocculent and conditioning agent is employed and used simultaneously, for example the combination of aluminium sulphate and magnesium sulphate, the ratio is preferably from 2:1 to 1:2, more preferably 1.5:1 to 1:1.5 and most preferably 1.25:1 to 1:1.25. Alternative conditioning agents for adjusting cation concentration, and effective concentration ranges, would be readily apparent to the skilled addressee, depending upon the ion concentration in the waste water being treated and the soil type upon which the recycled waste water is intended to be used.

Water conditioning of the present invention is generally in contrast to conditioning often associated with hard water, i.e. water containing Ca²⁺ and Mg²⁺ ions, when used for domestic washing and cleaning. In this regard, Ca²⁺ and/or Mg²⁺ ions are often removed by the action of sodium carbonate or Na-zeolite ion exchange systems. As discussed above however, the invention addresses the problems that excess Na⁺ can cause on soil structure when waste water is used on gardens and lawns.

Irrigation water containing large amounts of sodium is of special concern due to sodium's effects on the soil. Continued use of water having high sodium content can lead to a breakdown in the physical structure of the soil. Specifically, sodium is adsorbed and becomes attached to soil particles. The soil then becomes hard and compact when dry and increasingly impervious to water penetration. Fine textured soils, especially those high in clay, are most subject to this action. Calcium and magnesium, if present in the soil in large enough quantities, will counter the effects of the sodium and help maintain good soil properties.

Sodic soils may impact plant growth by: 1) Specific toxicity to sodium sensitive plants; 2) Nutrient deficiencies or imbalances; 3) High pH; and 4) Spread of soil particles that causes poor physical condition of the soil. Sodic soils tend to develop poor structure and drainage over time because sodium ions on clay particles cause the soil particles to deflocculate, or disperse. Sodic soils are hard and cloddy when dry and tend to crust. Water intake is usually poor with sodic soils, especially those high in silt and clay. Poor plant growth and germination are also common. The soil's pH is usually high, often above 9.0, and plant nutritional imbalances may occur. Sodium levels in soil are often reported as the sodium adsorption ratio (SAR). This is a ratio of the amount of cationic (positive) charge contributed to a soil by sodium, to that contributed by calcium and magnesium. The SAR is determined from a water extract of a saturated soil paste. A SAR value below 3 is desirable. If the SAR is above 3, sodium can cause soil structure deterioration and water infiltration problems.

The method of the invention may optionally include the addition to waste water undergoing treatment of a pH balancing agent, typically an alkalising agent, if required. Preferred alkalising agents include magnesium carbonate, magnesium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate and magnesium oxide.

Depending upon the particular waste water to be treated, the chemical or combination of chemicals used as the conditioning agent may be very similar, or even the same, as those employed to adjust pH. If essentially the same chemical is employed in the conditioning agent and pH balancing agent, its use may however differ with respect to when it is added to waste water undergoing treatment, the concentration at which it is added, and/or the state or form of the chemical, including solids, liquids, salts and levels of oxidation.

The pH of treated grey water according to the invention is generally in the range of pH 4.0 to 9.0, however is preferably in the relatively neutral range of 5.5 to 8. The pH balancing agent can be added to waste water undergoing treatment as a single unitary dose, comprising one or more distinct chemicals, or alternatively, may be added as multiple doses of one or more chemicals at different stages in the waste water treatment process.

Waste water treatment according to the invention may also optionally include the addition of a chemical sterilizing agent effective against transmissible agents, including water borne microorganisms, including for example fungi, bacteria, and viruses. Useful sterilising agents include calcium hypochlorite, phenol, chloroxylenol, thymol, hydrogen peroxide, ozone, chloramine, iodine, peracetic acid, potassium permanganate, potassium peroxymonosulphate or bromine. The invention provides a method and apparatus for treating waste water which particularly takes into account the adverse consequences that waste water can have on soil condition and structure. At the same time, water purified according to the invention needs to be hygienically safe, whilst for practical and economical reasons, generally does not need to meet strict regulatory requirements such as those for recycled water intended for human consumption. The inventors have surprisingly devised a unique method and apparatus that is able to balance these competing objectives.

The preferred embodiment describes an apparatus and method for treating domestic laundry effluent rendering it suitable for irrigation, as a major source of household waste water is that generated by a household laundry. The skilled addressee will however appreciate that the invention could be employed in a commercial laundry, or with a different source of grey water, such as that generated in a domestic or commercial kitchen, or domestic or commercial baths. Successful development of the preferred embodiment is particularly surprising given that laundry grey water is generally considered to be the dirtiest produced in a household, and has a high level of salts which are detrimental to soil structure.

Depending on the cleanliness of the clothes being washed, the type of laundry detergent, and the type of clothes washing machine used, laundry waste can contain a broad range and concentration of impurities. The inventors have discovered that laundry waste water is typically alkaline and contains sodium and phosphorus, fats, oils and greases, with high suspended solids, resulting in high biological oxygen demand (BOD) and faecal coliforms. The high levels of suspended solids are a combination of organic and inorganic particles. The high BOD contributes to increased microbial activity with unpleasant odours on storage. The elevated levels of faecal coliforms can cause a direct risk to human health.

As mentioned above, laundry waste water is typically alkaline, with pH commonly between 8 and 11. Addition of alkaline laundry waste water to soil may increase the soil pH which can damage the soil and effect plant growth. In particular, nutrients required for plan growth are not available for plants if the soil has the wrong pH. The inventors have tailored the method and apparatus of the invention to reduce the pH of treated laundry waste water to between pH 4.0 and 9.0, more preferably between 5.5 and 7.5. Laundry powders typically contain a high level of phosphorus, generally as phosphates, which can damage plants and the environment through untreated grey water use. Whilst phosphorus is an important nutrient for plant growth, many plants, especially Australian natives, are intolerant to high concentrations. In addition, phosphorus contamination of ground water can cause undesirable algal blooms. Accordingly, it is highly desirable that any grey water treatment system reduce phosphorus levels in treated grey water.

In Australia, for example, there are two phosphorus ratings for laundry detergents, NP - no added phosphorus, and P - less than 7.8g P/wash. Through experimentation, the inventors have determined that concentrations of phosphorus in laundry waste water range from about 5mg/L for NP detergent to about 53mg/L for P detergents. The method of the invention has been found to reduce phosphorus levels in laundry waste water by up to 99.8%.

The apparatus and method of the preferred embodiment seeks to purify laundry effluent to a degree that it is suitable for irrigation purposes in a sustainable way without contaminating and damaging garden soils. The process seeks to reduce the turbidity of laundry grey water to less than 5 Nephelometric Turbidity Units (NTU), typically between 1 and 5 NTU. In contrast, drinking water typically has a NTU less than 0.5. According to the invention NTU is measured pre- filtration and without settling.

According to one aspect of the invention, grey water dispensed from a clothes washing machine is diverted from the machine and collected in a collection vessel. Treatment of the collected grey water is firstly with a flocculent, such as aluminum sulphate, to cause flocculation of suspended particles. A conditioning agent, such as magnesium sulphate, may also be added to adjust cation concentration, if required. Further, the pH of the grey water may be adjusted if necessary with an alkalising agent, such as powdered light magnesium carbonate, to a pH between 5.5 and 7.5. The method of the invention produces purified water that has little if any effect on the SAR value or pH of irrigated soils. Introduction of calcium hypochlorite, or similar sterilizing agent, in the conditioning mix may optionally be used to reduce faecal coliforms in the purified water. The facile and effective purification of laundry waste water according to the invention is particularly surprising given that laundry waste is generally considered to be the dirtiest grey water produced by households. Depending upon the type of washing machine, i.e.: front loader or top loader, a suitable grey water treatment regime, including an amount of flocculent, an amount of conditioning agent, and/or an amount of pH balancer, is chosen. According to the invention, the treatment regime may be based upon the specific requirements of a particular washing detergent, or alternatively a generic regime may be employed based upon a range of detergents.

Figure 1 depicts a schematic of a water purification apparatus employing liquid dosing of flocculent, conditioner and/or pH balancer. Referring to Figure 1, the apparatus includes waste water collection vessel 10, inlet diverter valve 11 and hose 12, overflow 14, drain valve 15 and hose 16, flocculent dosing pump and storage 18, conditioner dosing pump and storage 20, filters 22 and 24, UV sterilizer 26, irrigation outlet 28, electronic control system and user interface 30, recirculate /process diverter valve 32, low level switch 34, main processing pump 36, and electrically actuated ball valves 38 and 40.

Inlet hose 12 is connected to the outlet hose from, for example, a domestic clothes washing machine (not shown). Waste water discharged from the washing machine is collected in collection vessel 10. Collection vessel 10 can be of any practical size; however is preferably 200-500 litres in capacity. Most preferably, collection vessel 10 is approximately 250 litres so that the apparatus is easily mobile and can be carried or wheeled. In this regard, the apparatus of the invention may be retained by the householder if they move house and is similar in this regard to other household appliances such as washing machines or dishwashers.

In use, collection vessel 10 is filled with waste laundry water pumped from a washing machine. In an alternative embodiment not shown, inlet hose 12 can employed in combination with a pump to siphon water from, for example, a bath or basin into collection vessel 10. Once collection vessel 10 is full of waste water it is dosed with a combination of an aluminium sulphate solution from pump 18 and a suspension of magnesium hydroxide from pump 20. This combination causes the suspended solids to flocculate and settle to the bottom of the collection vessel 10, reducing the alkalinity of the water to between pH 6.5 and 8, balancing the sodium ions with sufficient magnesium ions to negate the impact of Na⁺ ions on soil structure, removing the majority of the phosphorus as insoluble magnesium aluminium phosphates and the majority of the organic material.

After settlement the system filters the water in vessel 10 through a particulate filter 22 with a nominal rating of 0.5 μm or better. The treated water has a low level of suspended solids and a greatly reduced concentration of nutrients, and is discharged via outlet 28 for use with any irrigation system. Diverter valve 11 prevents laundry waste entering the system whilst waste water contained therein is undergoing purification treatment.

The particulate filter for use in accordance with the invention is preferably an absolute or depth filter, including pleated or spun thread filters. Suitable depth filters preferably have a nominal rating below 0.5 μm, or more preferably below 0.35 μm. Reducing particulate content is particularly important where treated water is intended for use in irrigation systems, such as dripper systems, where pipe fouling and clogging must be avoided. The skilled addressee would be aware of analogous filters for use in the invention and could readily select a filter depending upon the level of particulate matter acceptable in the treated water. Where particulate matter in the treated water is of no consequence, the filter can be omitted.

Optionally, a GAC filter 24 and a UV sterilizer 26 can be used to further reduce the level of organic matter and faecal coliforms to a level suitable for surface irrigation.

Advantageously, the portable and modular apparatus of the preferred embodiment does not need to be permanently connected to household plumbing by a licensed plumber and can simply be attached by the homeowner to their washing machine. The apparatus thus allows for flexibility and variety in use not afforded by other systems. Moreover, the apparatus can be easily carried or moved from one place to another to be in close proximity to a source of waste water or an area in need of irrigation. The complete system preferably comprises a unit approximately of the size of a washing machine. Preferably, the system can be placed outside the building close to the laundry window and exposed tundish to the laundry waste. The apparatus will be plugged into a standard power point either on the exterior of the house or in the laundry. The waste water pipe from the washing machine will be extended to direct the waste water into the collection tank 10 of the system.

Preferably, the apparatus of the invention automatically dumps excess waste water to sewer via overflow 14. In this regard, when a user has collected sufficient waste water the extension hose from the washing machine waste pipe may be disconnected. The user can then determine the water level in the collection tank 10 visually using a gauge on the side of the unit. To treat the water in the vessel 10, the customer initiates an automatic treatment process by activating a switch on the user interface of the electronic control system 30. After treatment is complete, the user can pump the treated water to an attached irrigation system by activation of a pump. Preferably, if the water in collection vessel 10 is left unused for more than 7 days it will automatically be dumped to waste.

The method and apparatus of the invention also envisages the incorporation of additional water purification technology in the purification of waste water. For example, the inclusion of a disinfection step or agent including chlorination, bromination, iodination, chlorine oxide, hydrogen peroxide, ozonolysis, electroporation and/or UV radiation.

Figure 2 is similar to Figure 1, except that it depicts manual powder dosing of flocculent and conditioner. As for figure 1, figure 2 includes waste water collection vessel 10, inlet diverter valve 11 and hose 12, overflow 14, drain valve 15 and hose 16, flocculent dosing chamber 18, conditioner dosing chamber 20, filter 22, irrigation outlet 28, electronic control system and user interface 30, recirculate process diverter valve 32, low level switch 34, main processing pump 36, and electrically actuated ball valves 38 and 40.

The dosing chambers can be manually activated to deposit their contents into the waste water undergoing treatment. Alternatively, waste water undergoing treatment may be pumped through the base of the dosing chambers to effectively mix the contents of the containers with the waste water. Typically, waste water undergoing treatment would first be pumped through flocculent dosing chamber 18 and any floe removed, before being pumped through conditioner dosing chamber 20. A single pump can be employed in the apparatus of Figure 2 to pump water via dosing chambers 18 and 20 and thereafter from the apparatus. Alternatively, two or more separate pumps could be employed.

The invention will now be described with reference to a number of examples. The examples are by way of illustration and not as limitations of the invention.

EXAMPLES

Example 1 - Dosing of Grey Water - Top Loading Clothes Washing Machine

Laundry grey water was treated in a two stage dosing regime, with each dose comprising the following:

Dose 1

Aluminium Sulfate (Alum) 0.3 - 2.7 g/L Flocculation

Magnesium Sulfate (Epsom salts) lg/L Magnesium Ions, not pH change

Dose 2

Magnesium Carbonate 0.1 - 0.25g/L pH increase

Calcium Hypochlorite 0.05g/L Steriliser

The first dose typically reduces the pH to 4.2-4.6 with good flocculation and settling. The second typically increases the pH to between 5.5 and 7.

The procedure involved filling six 2 litre glass jars with grey water, checking and recording the pH of starting water, dosing each jar with Alum at the rate of 0.8, 0.9, 1.0, 1.1, 1.2 and 1.3g/L, mixing the grey water in each jar for 2-3 minutes until the Alum granules dissolved. Once floe occurred, observe the level of floe and turbidity, measure and record pH of each jar, raise the pH by adding 0.2g/L of magnesium carbonate to each jar and mix for 40 minutes¹.

Different doses of aluminium sulphate were employed to reduce the pH into the desired field for a range of detergents. See Table 1, below. Also FIG 3 is a graph of the pH change for 14 common detergents. As demonstrated in FIG 3, overdosing does reduce the pH to below the desired range; and minor overdosing was not found to be damaging to floe formation.

A suitable dose of aluminium sulphate for the majority of laundry detergents is 0.8g/L. Detergents without filler, such as Amway SA8, require a lower dose of 0.6g/L. Detergents for front loaders and Aware environmentally friendly detergent require a high dose of 1.5g/L.

A combination of flocculent and conditioning agent was also tested and the following dosing concentrations found highly suitable for treating top loader grey water.

Dose 1

0.8g/L aluminium sulphate lg/L magnesium sulphate

Dose 2

0.3g/L magnesium carbonate

0.05g/L calcium hypochlorite

Example 2 - Dosing of Grey Water - Front Loading Clothes Washing Machine

As in Example 1 above, laundry grey water was treated in a two stage process. The first stage involves dosing with both aluminium sulphate and magnesium sulphate, the second stage involves dosing with magnesium carbonate and calcium hypochlorite.

Optimal granular aluminium sulfate and magnesium carbonate doses for a broad range of front loader laundry detergents were determined. The target pH of the treated grey water was 4.2 to 4.6 from the starting pH of 7-10. Aluminium sulfate was tested in the range of 0.4g/L to 2.7 g/L.

The results of Example 2 are depicted in Figure 4 which shows the pH of different samples of grey water as a function of the Alum dose (g/L) for 16 common front loader detergents. Table 2 below shows a comparison between the different liquids at their most appropriate dose of Alum and also magnesium carbonate. The Hurricane Planet, Amway SA8 and the Biozet were the best performers. The Ecochoice was the worst performer. Other liquids performed well, but required a high dose of Alum in order to get the sample to flocculate. Turbidity is measured in NTU and measurements are pre- flltration with no settling.

The results indicate that from the washing detergents analysed, the Ecochoice liquid was the only sample that did not readily allow particles to settle from the grey water. This is most likely due to a buffer in the solution which enables the minute particles in the water to remain in suspension.

The results suggested that Biozet, Amway S A8 and Hurricane Planet Green Ultra are possibly the best laundry detergents for use with the invention with optimal dosing of 0.8, 1.2 and 1.3g/L alum, respectively. The Biozet and Amway AS8 require only a relatively small dose of magnesium carbonate in order to raise the pH to within the optimal range for safe garden use. Hurricane Green Planet Ultra does not require a dose of magnesium carbonate in order to raise the pH, as the pH is within the optimal range after Alum dosing of 1.3g/L.

Detergents including Woolworths Select Powder, Aldi Trimat and Coles Matic Concentrate require much higher doses of Alum in order to get the grey water to flocculate. These higher doses range from 2.6 g/L of Alum for the Woolworths Select Powder, up to 3.2 g/L of Alum for the Coles Matic Concentrate. These three detergents only require the same low dose of magnesium carbonate in order to raise the pH to the required level for safe garden use.

Example 3 - Dosing of Grey Water - Top Loading Clothes Washing Machine

Grey water resulting from the use of the following list of popular laundry detergents was tested for pH before and after treatment employing the regime developed in Example 1.

1. Amway S A8 powder

2. Aware Powder

3. BioZet powder

4. Cold Power Liquid

5. Dynamo Matic liquid

6. Omo High Performance Powder

7. Omo Sensitive Powder

8. Omo High performance Liquid

9. Omomatic powder

10. Surf Powder

Typical results for laundry grey water are listed below in Table 3.

Example 4 - Phosphorus Reduction and Sodium Adsorption Ratio (SAR) - Top Loading Machine

Three grey water samples from laundry grey water with a high phosphorus detergent, Omo matic, as rated by the Lanfax laboratories, were treated according to the regime developed in Example 1. Average dosage of treatment chemicals was 45Og (aluminium sulphate and magnesium sulphate in 1:1.25) and 9Og (magnesium carbonate and calcium hypochlorite in 1 :0.16) for 250 litres of grey water. The results are shown below in Table 4.

Table 5 shows the same test with a grey water sample from a different laundry detergent, Omo Sensitive.

The example demonstrates that the invention can reduce phosphorus by up to 99.8%. Sodium Adsorption Ratio (SAR) salts of the treated water were also tested, see Table 6 below. Values above 3 can cause permanent damage to soil. Results demonstrate that the invention has the potential to reduce SAR to near 1.

Example 5 - Laundry Grey Water Treatment Apparatus

The following example describes one preferred apparatus according to the invention. The example should be read in conjunction with Figs 5 to 16. The apparatus can be employed for conditioning washing machine grey water for subsurface irrigation, and particularly for use on garden and lawn areas. Typically, the apparatus sits in close proximity to a laundry, so that washing machine grey water can be transferred easily from the washing machine to the apparatus via a connection hose. When enough washing machine grey water is collected for a batch, a prescribed dose of flocculent and conditioning agent is added.

The key components of the apparatus 50 are as in the following list and with reference to Figs. 5 to 16.

Λ'ϊisϋiiFt

1 Access door

2 Clean water outlet (to subsurface irrigation)

3 Control panel

4 Dosing chamber for GardenAngel Soil Protector (left) - yellow

5 Dosing chamber for GardenAngel pH Balancer (right) - blue

6 Drain hose

7 Drain outlet

8 Stand

9 Electrical cord

10 Filter cartridge

11 Filter housing

12 Filter spanner

13 Hose connector

14 Hose nipple

15 Level gauge

16 Levelling foot (x4)

17 LId

18 Lilac extension hose with connector

19 Washing machine connection hose

20 Washing machine inlet

Table 7

In setting up the apparatus 50 for use, washing machine connection hose 19 is extended and fitted to the outlet of a clothes washing machine via inlet 20. Drain hose 6 is attached to drain outlet 7 and stand 8; extension hose 18 is attached to clean water outlet 2, and power cord 9 is plugged into an electrical outlet.

It is highly preferable that the apparatus 50 is positioned as near as possible to a laundry door or window and an outside gully trap or tundish. Such an arrangement is depicted in Fig. 6, which includes apparatus 50 positioned outside a laundry, with easy access to a clothes washing machine 54 and gully trap 52. As depicted in Fig 6, the waste from the apparatus 50 is drained to the gully trap by gravity. Thus, the apparatus is best placed below the level of the washing machine and above the level of the outside gully trap or tundish.

The gully trap arrangement is further depicted in Fig. 7, which includes gully trap 52, drain outlet 7, drain hose 6, and drain stand 8. According to the instant embodiment, one end of the drain hose 6 is attached at the base of the apparatus 50, and the discharge end of the hose is fixed over the gully trap 52 by drain stand 8. This arrangement allows water to be diverted to the sewer. According to the invention typically about 90 percent of the waste water treated can be purified for reuse. The remaining about 10 percent is diverted to the sewer.

With reference to Fig. 6, the washing machine connection hose 19 of apparatus 50 is attached to the outlet hose of a regular clothes washing machine. AU grey water from the connected washing machine is collected by the apparatus and any excess is automatically diverted to sewer via the drain hose. Similarly, if garden-ready water remains in the apparatus, any new raw water will be automatically diverted via the waste outlet to the drain.

In some jurisdictions regulations govern the length of time untreated grey water can be stored, and accordingly the apparatus can be preset to dump treated grey water after a specified period of time, for example 24 hours. A treatment cycle may of course be activated anytime before the untreated grey water is due to be dumped. Treated grey water can be stored in the apparatus for any length of time. However, the option is also available to dump treated grey water after a specified length of time, for example 7 to 14 days.

A subsurface irrigation hose 18 is connected to the clean water outlet 2 of the apparatus 50, using a snap-on hose adaptor. The hose 18 can be used to connect to a subsurface irrigation system.

The apparatus of the example can be used to treat the typical detergent and soil loads of a standard washing machine. The apparatus ideally remains connected to an electrical power source when it is processing or holding water, and is equipped with a low-power standby mode that can be manually operated. Fig 7 depicts an example of a suitable control panel for the apparatus. Table 8 below summaries in detail the various features of the control panel.

drain system

Table 8

With reference to Fig 8 and Table 8, the apparatus 50 is turned on by activating the blue power switch on the control panel 3. An illuminated yellow light indicates that there is raw water in the apparatus ready for treatment. On the side of the apparatus a water level gauge 15 (see Fig 5), indicates how many litres of grey water needs to be treated, and thus the amount of flocculent and conditioning agent that needs to be added prior to treatment can be determined. After adding the treatment agent(s) to the apparatus, the yellow process button is pressed to begin the grey water conditioning cycle, which takes approximately 3.5 hours to complete. Upon completion of the treatment cycle, garden- ready water can be used for garden irrigation. Alternatively, if no longer required for irrigation, treated water can be dumped to sewer by activating the red Dump (!) switch on the control panel 3.

With reference to Figs. 9(a) and 9(b), a precise amount of flocculent and conditioning agent(s), including cation concentration adjuster, pH balancer and sterilizer, is added to the apparatus 50, via dosing chambers 4 and 5. To optimize grey water treatment, it is important that the correct amount of flocculent (labeled in Fig 9(a) as Soil Protector), based upon the amount of grey water to be treated, is added to dosing chamber 4. Typically, a conditioning agent comprising a cation adjuster would be added with the flocculent to chamber 4. Similarly, the correct amount of pH balancer, and optionally a sterilizer, for the volume of water to be treated must be added to dosing chamber 5.

As mentioned above, the yellow treatment process switch/ button is activated to begin a treatment cycle and flashes for the duration of the process. An illuminated blue distribute light indicates when the cycle is complete and water is available for garden use. Activating the blue distribute button /switch pumps the grey water through the filter cartridge 10 before being distributed to the irrigation system. A flashing blue light indicates that treated water is being pumped from the apparatus.

Distribution of conditioned water through a subsurface irrigation system typically takes between 20 and 60 minutes depending upon the type of irrigation system and the condition of the filter 10. Once all treated water has been distributed, the flashing blue light, indicating that water is being pumped from the apparatus, is extinguished. The apparatus will automatically dump water at the end of the distribution process. Dumping typically takes about five minutes during which time no new unconditioned water can be accepted. Dumping is indicated on the control panel 3 by a flashing red light.

A red light on the control panel 3 is illuminated when the filter 10 is blocked and needs to be replaced. Generally, the filter 10 requires changing when distribution of conditioned water to the attached irrigation system is taking longer than usual. Whilst the apparatus will continue to operate with the change filter light lit, the apparatus may have reduced performance.

With reference to Fig 10, the filter cartridge 10 can be accessed by opening door 1 in the side of the apparatus 50. A filter spanner 12 is employed to unscrew the filter housing 11 in the direction of arrow A. Once unscrewed, the filter housing 11 can be pulled downwards from the apparatus in the direction of arrow B.

As depicted in Fig. 11 the filter housing 11 is removed from the apparatus in the direction of arrow A. The old filter 10 is removed from the filter housing 11 as indicated by arrow B, and a replacement filter is placed in the centre of filter housing and the filter housing, and new filter, fitted to the apparatus using the filter spanner 12.

The described apparatus can process up to about 250 litres of grey water per batch. This generally equates to approximately two loads in a top loading washing machine, or four loads in a front loading machine. Whist one condition cycle takes approximately 3.5 hours, multiple batches can be treated in one day.

Fig 12 depicts a grey water storage and treatment vessel 60 suitable for use in the apparatus of this example. Generally the vessel 60 can be manufactured from plastic, including thermoplastic, for example polyethylene. A combination of materials may also be employed. Alternative materials, or combinations of materials, would be readily apparent to the skilled addressee. The vessel 60 must be capable of holding up to about 250 litres of water and so preferably includes strengthening ribs 62. The vessel also includes top 64, dosing chambers 4 and 5 and lugs 66. Fig 13 depicts a dosing chamber 5 for attachment to the lid of vessel 60. The dosing chamber includes plumbing connection 68 and opening 70. In use, a measured amount of treatment agent(s) is placed in opening 70. As best illustrated in the cross sectional view of Fig 14, the treatment agent(s) deposited in opening 70 is mixed with water in the collection vessel when water is pumped from the collection vessel through plumbing connection 68 and back into the collection vessel. When multiple dosing chambers are employed, the contents of a first dosing chamber can be mixed with water in the collection vessel by activation of a pump that pumps water through the first dosing chamber plumbing connection and back into the collection vessel. The contents of a second, or subsequent, dosing chamber can be mixed with water in the collection vessel by pumping water through the second or subsequent dosing chamber, before the water is returned to the collection vessel. Water pumped through the plumbing connection of the dosing chamber causes a vortex which carries the treatment agent from the chamber.

As depicted in Fig 15, the dosing chamber may be comprised of an upper section 72 and a lower section 74. Preferably, the upper section is constructed of the same material as the collection vessel, for example polyethylene or similar material. The lower section is preferably of hard plastic, such as PVC or similar, and suitable for attachment to a plumbing fixture.

With reference to Figs. 12 and 16 the collection vessel 60 according to the present example includes during manufacture the incorporation of numerous protrusions or lugs 66. Such lugs can conveniently be drilled through to allow plumbing connections to be fixed to the collection vessel 60. For example, Fig 16 depicts a lug that has been drilled and thread tapped 76. The size of the lug is generally determined by the size of the plumbing fitting required. Suitable lugs are from about 10 to 50 mm, to cater for common thread sizes.

It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in the art of this invention.

Claims

1. A portable and/or modular apparatus for purifying waste water for subsequent use in irrigation, comprising:

- an inlet which is capable of attaching directly to and receiving waste water from an outlet hose of a clothes washing machine;

- a waste water collection vessel;

- a first dosing chamber; and

- a purified water outlet.

2. The apparatus of claim 1 , further comprising a waste water outlet.

3. The apparatus according to claim 2, further comprising a second dosing chamber.

4. The apparatus of claim 3, wherein the collection vessel has a capacity of 200- 500 litres.

5. The apparatus of claim 4, wherein the collection vessel has a capacity of 250- 350 litres.

6. The apparatus of any one of claims 1-5, wherein the inlet is capable of being reversibly connected to the outlet of a clothes washing machine.

7. The apparatus of any one of claims 1 -6, wherein the purified water outlet is configured for reversible connection to an irrigation system.

8. The apparatus of any one proceeding claim, wherein the apparatus is programmed to dump any water in the collection vessel after an interval of time.

9. The apparatus of any one preceding claim, wherein the apparatus includes a pump capable of pumping waste water in the collection vessel through the first or second dosing chamber.

10. A method of treating waste water for subsequent use in irrigation, comprising contacting waste water with the following: a) a fiocculent; b) a conditioning and/or pH balancing agent; and removing floes from the treated water to produce purified water, wherein the purified water has a turbidity of at least 1 NTU.

11. The method of claim 10, wherein the waste water is laundry waste water.

12. The method of claim 10, wherein the purified water has a turbidity between 1 and 5 NTU.

13. The method of claim 11 , wherein the purified water has a SAR of less than 3.

14. The method of claim 11 , wherein at least 90 percent of the phosphorous is removed from the waste water.

15. The method of any one preceding claim, wherein the conditioning agent is one or a combination of chemical agents that are added to the waste water to balance or adjust Na⁺, Mg²⁺, Ca²⁺ or K⁺ cation concentration.

16. The method of claim 15, wherein the pH of the purified water is 5.5 to 8.

17. The method of claim 16, wherein the flocculent includes aluminium sulphate.

18. The method of claim 17, wherein aluminium sulphate is liquid 8% Al₂O₃ or solid 17.3% Al₂O₃.

19. The method of claim 18, wherein the aluminium sulphate is liquid and added to the waste water at the rate of 0.2 mL/L to 2.0 mL/L.

20. The method of claim 19, wherein the aluminium sulphate is added to the waste water at the rate of 0.6 mL/L to 1.2 mL/L.

21. The method of claim 17, wherein the aluminium sulphate is solid and added to the waste water at the rate of 0.10 grams/L to 1.50 grams/L.

22. The method of claim 21, wherein aluminium sulphate is added to the waste water at the rate of 0.6 grams/L to 1.0 grams/L.

23. The method of any one preceding claim, wherein the conditioning agent includes one or more of the following: magnesium hydroxide, magnesium carbonate, magnesium sulphate, calcium hydroxide (lime), calcium sulphate (gypsum), calcium carbonate and calcium hypochlorite.

24. The method of claim 23, wherein the conditioning agent includes magnesium sulphate.

25. The method of claim 23, wherein the conditioning agent includes magnesium hydroxide liquid.

26. The method of claim 25, wherein the conditioning agent is 55% magnesium hydroxide liquid applied at the rate of 0.18 +/- 0.03 mL/L.

27. The method of claim 23, wherein the conditioning agent is magnesium carbonate.

28. The method of claim 27, wherein the magnesium carbonate is applied at the rate of 0.21 +/- 0.03 grams/L.

29. The method of any one preceding claim, wherein the method further includes contacting the waste water with a depth filter.

30. The method of claim 29, wherein the depth filter is a pleated depth filter with a nominal rating below 0.5 μm.

31. The method of claim 10 when used in conjunction with the apparatus of any one of claims 1-9.