Device and system for improved cleaning in a washing machine
A washing system for cleaning within a washing zone comprising at least one inlet capable of fluid communication with a feed water; at least one treatment zone in fluid communication with the at least one inlet, said at least one treatment zone comprising a water softening zone, an electrolysis zone, a dosing zone and combinations thereof; and at least one outlet in fluid communication the at least treatment zone capable of being in fluid communication with a washing zone.
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This application claims the benefit of EP Patent Application No. 04252837.2, filed May 17, 2004, EP Patent Application No. 04252849.7, filed May 17, 2004, EP Patent Application No. 04252846.3, filed May 17, 2004, EP Patent Application No. 04252838.0, filed May 17, 2004, EP Patent Application No. 04252853.9, filed May 17, 2004, EP Patent Application No. 04252851.3, filed May 17, 2004, EP Patent Application No. 04252845.5 and U.S. application Ser. No. 10/967,757, filed Oct. 18, 2004.
BACKGROUND OF THE INVENTIONIn recent years there has been growing interest in a variety of non-detergent based technologies for washing laundry and other soiled substrates. For example, a number of washing machines have been launched on the Japanese and Asian markets that make use of electrolysis, ultrasonic or cavitation techniques to promote the cleaning or disinfection of laundry. Typically, such machines include at least one wash cycle characterized as ‘detergent-free’ and which is designed for the washing of laundry that is relatively lightly soiled. As the washing machine manufacturers themselves make clear, however, the machines and systems currently on the market are of limited value for the washing of more heavily soiled or stained items where the use of a surfactant-based detergent product continues to be necessary to achieve acceptable cleaning performance. Accordingly, such machines are designed and marketed for so-called ‘hybrid’ use with non-detergent and detergent wash-cycles being selectable according to the severity of the laundering task.
In terms of overall resource utilization, the non-detergent based cleaning technologies may have the potential to save on detergent product usage in light soil situations, but such savings are offset to a lesser or greater extent by the operational need for higher water and energy utilization. Thus the resource equation is finely balanced.
One difficulty in adopting any change to cleaning technologies relates to the enormous capital investment that has been made worldwide in the current types of washing machine equipment. Asking owners of this equipment to wholly replace their machines with new machines would require significant investment by the owners, as well as create a glut of obsolete washing machines having limited use.
It clearly would be desirable to enhance the efficacy of current washing machines and systems, including the newer ‘hybrid’ machines, so as to deliver improved washing performance across the full range of detergent usage levels. It would also be desirable to deliver performance improvements in the context of an overall efficient and sustainable utilization of resources—chemical, water and energy.
It is an object of the present invention to provide methods and systems applicable in the field of domestic or institutional appliances such as laundry washing machines, automatic dishwashing machines, etc and which enable improved cleaning of a soiled substrate or substrates across the range of detergent usage levels. It is a further object of the invention to provide washing methods and systems enabling more efficient usage of water, energy and detergent product resources. It is yet another object of this invention to provide such methods and systems that can be retrofitted or otherwise utilized in concert with existing domestic or institutional appliances.
SUMMARY OF THE INVENTIONThe present invention relates to a washing system for cleaning within a washing zone comprising at least one inlet capable of fluid communication with a feed water; at least one treatment zone in fluid communication with the at least one inlet, said at least one treatment zone comprising a water softening zone, an electrolysis zone, a dosing zone and combinations thereof; and at least one outlet in fluid communication the at least treatment zone capable of being in fluid communication with a washing zone. In one embodiment the washing zone is capable of cleaning or washing substrates comprises laundry and dishware. In one embodiment the water softening zone comprises nanofiltration devices, electrodeionization devices, electrodialysis devices, reverse-osmosis devices capacitive deionization devices, flow-through capacitors and ion-exchange water-softening devices and combinations thereof. In one embodiment the water-softening zone comprises capacitive deionization. In one embodiment the at least partially softened water comprises a residual Ca2+ hardness of less than about 4 mmol/L. In one embodiment at least partially softened water comprises a soft water flux of at least about 2 L/h at a feed water pressure from about 100 to about 1000 kP. In one embodiment the device and the washing zone are housed substantially within one housing. In one embodiment the device and the washing zone are independently housed. In one embodiment the dosing zone is fluidly connected between the at least one inlet and at least one outlet and capable of dispensing a fabric care composition. In one embodiment, the present invention further comprises a mixing zone functionally connected between the dosing zone and the outlet capable of at least partially mixing the fabric care composition with a second fluid. In one embodiment the mixing zone comprises in-line mixers comprising, venturi flow, direct injection pumps, peristaltic pumps, gravity feeds, and spraying; sonic mixers; ultrasonic mixers; and combinations thereof. In one embodiment from about 0.01 to about 50 grams of fabric care composition are dispensed by the dosing zone. In one embodiment at least one water softening zone and at least one electrolysis zone. In one embodiment, the washing system comprises a first water softening and a second water softening zone; and a first electrolysis zone and a second electrolysis zones wherein the first water softening zone is fluidly connected to the first electrolysis zone and the second water softening zone is fluidly connected to the second electrolysis zone. In one embodiment, the present invention further comprises at least one check valve between the at least one inlet and the at least one outlet. In one embodiment, the present invention further comprises at least one sensor capable of sensing at least one water level, density, conductivity, pH, vibration, temperature, turbidity, viscosity, and combinations thereof.
DETAILED DESCRIPTION OF THE DRAWINGS
While the specification concludes with the claims particularly pointing and distinctly claiming the invention, it is believed that the present invention will be better understood from the following description.
The compositions of the present invention can include, consist essentially of, or consist of, the components of the present invention as well as other ingredients described herein. As used herein, “consisting essentially of” means that the composition or component may include additional ingredients, but only if the additional ingredients do not materially alter the basic and novel characteristics of the claimed compositions or methods.
All percentages and ratios used herein are by weight of the total composition and all measurements made are at 25° C., unless otherwise designated. An angular degree is a planar unit of angular measure equal in magnitude to 1/360 of a complete revolution.
All measurements used herein are in metric units unless otherwise specified.
The term “product” as used herein encompasses both active-based detergent compositions suitable for washing and cleaning of soiled substrates as well as auxiliary compositions suitable for use after washing or in conjunction with active-based detergents and designed to provide an ancillary substrate benefit or effect, for example, finishing agents, rinsing agents, fabric enhancers designed to provide post-wash fabric care benefits, and detergent auxiliaries designed to provide post-wash surface care benefits. The terms “product dispensing zone,” “product storage means,” etc., should be construed accordingly.
The term “feed water” as used herein encompasses water directly from the mains including municipally available water and ground water, from the mains or used-water reservoir such as a recycle reservoir used for storage of recycled water, a storage tank, or from a combination thereof.
The term “laundry” as used herein encompasses woven and non-woven fabric. Non-limiting uses for this fabric include clothing, bedding, towels, and the like.
The term “washing zone” as used herein encompasses the volume whereby laundry, and/or product and/or a softened water are present to perform cleaning and/or washing. An example of a washing zone includes the volume created by the drum of an automatic washing machine.
It has now surprisingly been discovered that the washing system of the present invention provides improved cleaning and washing efficacy. Further, the washing systems can be utilized for a variety of cleaning or washing duties. According to a first aspect of the present invention, there is provided a washing system for cleaning within a washing zone comprising at least one inlet capable of fluid communication with a feed water; at least one treatment zone in fluid communication with the at least one inlet, said at least one treatment zone comprising a water softening zone, an electrolysis zone, a dosing zone, and/or combinations thereof; and at least one outlet in fluid communication with the at least one treatment zone capable of being in fluid communication with a washing zone.
In one embodiment, it is contemplated that the washing zone and the washing system of the present invention are independently housed. Such an embodiment is contemplated with washing systems that are at the point-of-use. In one non-limiting example, it is contemplated that the water-softening zone of the present invention is located in a different housing than the washing zone. The water-softening zone is fluidly connected between the feed water and the inlet of the washing zone. In such an embodiment, its is contemplated that existing devices utilizing feed water, including washing zones comprising washing machines and automatic dishwashing machines, water heaters, as well as “whole-house” inlet streams may be retrofitted and/or adapted to have such water softening zones present to treat feed water from the water supply.
In another embodiment, it is also contemplated that the washing systems of the present invention and the washing zone are contained substantially within one housing. Without wishing to be bound by theory, it is believed that by housing the washing systems of the present invention and the washing zone substantially within one housing minimises any plumbing or fluid connections necessary among the elements of the washing system. Also, housing the washing systems of the present invention and the washing zone substantially within one housing minimizes the volume and/or space required.
The washing systems of the invention can take the form of an integral water-softening and washing appliance wherein the water-softening zone and washing zone are built into and form part of a single appliance with the two zones in fluid communication with one another via the conduits of the appliance. In another embodiment, the washing system comprises a water-softening appliance and a washing appliance in hyphenated form, whereby the water-softening appliance and its associated water-softening zone forms a stand-alone unit that can be either permanently or temporarily fitted to the feed water inlet conduits of the washing appliance as required by the user, any power supply required for the water-softening appliance being taken either from the power supply for the washing appliance or separately from the mains power supply.
Systems and devices of the present invention are also advantageous in that water softening takes place without the use of ion exchange resins. Also, the increased cleaning benefit produced by the present invention results in less water/energy use to achieve an equivalent cleaning benefit versus water not treated by the present invention.
Water-Softening Zone
According to the invention, the washing systems herein comprise a water-softening zone. In the systems and methods of the invention, the water-softening zone comprises one or more devices comprising nanofiltration, electrodeionization, electrodialysis, reverse-osmosis, ion-exchange, and capacitive deionization water-softening devices and combinations thereof. In one embodiment, the water-softening zones can include those disclosed in the commonly-assigned and co-filed patent application in the name of Baeck, Convents and Smets, Applicant's reference number CM2849F, said application being incorporated by reference herein.
In one embodiment, the water softening zone is effective to soften the water forming at least partially softened water to a residual Ca2+ hardness of less than about 4 mmol/L, in another embodiment less than about 2 mmol/L, in yet another embodiment less than about 1 mmol/L, in still another embodiment from about 4 mmol/L to about 0.01 mmol/L, in yet still another embodiment from about 2 mmol/L to about 0.05 mmol/L, in even still another embodiment from about 1 mmol/L to about 0.1 mmol/L.
The specific conductance depends on the total concentration of the dissolved ionized substances, i.e., the ionic strength of a water sample. As used herein, it is an expression of the ability of the water to conduct an electric current. For example, freshly distilled water has a conductance of 0.5-2 μS/cm, whereas that of potable water generally is 50-1500 μS/cm. The method of determining the specific conductance in the present invention utilizes the following test: ASTM D5391-99 (2005): Standard Test Method for Electrical Conductivity of Flowing High Purity Water Samples.
In one embodiment, the water softening zone is effective to soften the water forming at least partially softened water to a specific conductance of less than about 200 μS/cm, in another less than about 150 μS/cm, in yet another embodiment less than about 100 μS/cm, in another less than 75 μS/cm, in another less than 50 μS/cm, in still another embodiment from about 0.01 μS/cm to about 200 μS/cm, in yet still another embodiment from about 0.1 μS/cm to about 100 μS/cm, in even still another embodiment from about 1 μS/cm to about 50 μS/cm.
Without wishing to be bound by theory, it is believed that the water softening zone will remove ionic species, including, but not limited to cationic species, anionic species, zwitterionic species, amphoteric species and combinations thereof. Such cationic species include, but are not limited to, calcium, iron, magnesium, manganese, sodium and mixtures thereof. Such anionic species include, but are not limited to, chlorine, fluorine, carbonate, sulphate, and mixtures thereof.
Downstream of the water-softening zone and in fluid communication therewith, the washing system can additionally comprise a softened water reservoir for storing and delivering at least partially softened water to the washing zone.
Without wishing to be bound by theory, it is believed that the water-softening zone forms an at least partially softened water. The at least partially softened water, when transferred to the washing zone, increases the efficacy of any product added to the washing zone. Further, it is believed that the at least partially softened water lengthens the usable life of components of the washing system, as the use of at least partially softened water reduces and/or prevents the build up of hard water deposits, scales, and the like resulting in cleaner washing system components.
In another embodiment, the water-softening zone utilizes capacitive deionization. Capacitive deionization units utilize charged electrodes for softening of the water. Capacitive deionization with electrodes is capable of removing ionic species and other impurities from water without the addition of other ions as is typical of an ion exchange water softener. Other forms of capacitive deionization include flow through capacitors which utilize similar fundamental physics. For the purposes of this invention capacitive deionization units include flow-thorough capacitors. Without wishing to be bound by theory, water is passed between electrodes kept at a low potential difference and/or voltage. Ionic species present in the water travel to its oppositely charged electrode. When the electrodes become saturated with ionic species, the electrodes are electrostatically regenerated, and ionic species are expelled as a waste electrolyte stream. Electrode regeneration involves periodically purging the electrodes of ionic species by reversing electrode polarity and flushing with water to form a waste electrolyte stream or by grounding the plates and flushing them with water to form a waste electrolyte stream. Further, the electrodes can be regenerated of adsorbed materials by contacting the electrodes with acid streams or base streams. In one embodiment, acid streams and base streams are generated by an electrolysis zone, as discussed herein.
In one embodiment, the electrodes of the capacitive deionization units are made from carbon aerogels. Carbon aerogel electrodes are found in U.S. Pat. No. 6,309,532 to Tran et el. Carbon-aerogel electrodes have excellent chemical stability and a very high surface area per unit volume.
In one embodiment, carbon aerogels are made utilizing various carbon systems. These systems are often, though not necessarily made by pyrolisis. These carbon systems include, but are not limited to, resorcinol/formaldehyde resorcinol/phenol/formaldehyde, hydroquinone/resorcinol/formaldehyde, phloroglucinol/resorcinol/formaldehyde, catechol/resorcinol/formaldehyde, polyvinyl chloride, phenol/formaldehyde, epoxidized phenol/formaldehyde, polyvinyl chloride, phenolibenzaldehyde, oxidized polystyrene, polyfurfuryl alcohol, polyvinyl alcohol, polyacrylonitrile, polyvinylidene chloride, cellulose, polybutylene, cellulose acetate, melamine/formaldehyde, polyvinyl acetate, ethyl cellulose, epoxy resins, acrylonitrile/styrene, polystyrene, polyamide, polyisobutylene, polyethylene, polymethyl-methacrylate, polyvinyl chloride/divinylbenzene, divinylbenzene/styrene, and combinations and mixtures thereof.
Other sources can be utilized to form electrodes for use in capacitive deionization units. In one embodiment, electrodes exemplified are U.S. Pat. No. 6,737,445 to Bell et al. and U.S. application No. 20030153636 to Dietz et al. are utilized, whereby these references are incorporated by reference. Further, the electrodes may be arranged in a flow through fashion, as described in U.S. Pat. No. 6,462,935 to Shiue et al. and U.S. application No. 20040095706 to Faris et al., whereby these references are incorporated by reference.
Additional electrode sources for use in capacitive deionization units are exemplified in the following U.S. patents and patent applications, all hereby incorporated by reference: U.S. Pat. Nos. 5,425,858; 5,636,437; 5,954,937; 5,980,718; 6,309,532; 6,346,187; and 6,761,809. U.S. patent Publication Nos. 2002-0084188 and 2004-0188246.
Further electrode sources, utilized in flow-through capacitors by the referenced materials as, for use in capacitive deionization units are exemplified in the following references, all hereby incorporated by reference: U.S. Pat. Nos. 5,192,432; 5,415,768; 5,547,581; 5,620,597; 5,748,437; 5,779,891; 6,127,474; 6,325,907; 6,413,409; 6,628,505; 6,709,560; 6,778,378; and 6,781,817. U.S. patent Publication Nos. 2004-0012913 and 2004-0174657. WO 01/66217 and WO 03/009920.
In one embodiment, the flow rate of feed water treated with capacitive deionization to make an at least partially softened water is from about 0.5 liters/min to about 20.0 liters/min, in another embodiment from about 0.75 liters/min to about 8 liters/min, in yet another embodiment from about 1 liters/minute to about 5 liters/min, in still another embodiment greater than about 1 liter/minute.
In one embodiment, the overall surface area of the electrodes utilized in the capacitive deionization unit is from about 200 to about 1500 m2/g; in another embodiment from about 400-1200 m2/g; in another embodiment from about 500-1000 m2/g.
In one embodiment the potential difference or voltage is from about 0.5 volts to about 10 volts; in another embodiment from about 0.75 to about 8 volts; in yet another embodiment from about 1 to about 5 volts.
In one embodiment, the capacitive deionization unit is capable of self-cleaning. In one self-cleaning embodiment, cleaning commences when the electrodes exhibit diminished adsorption of the ionic species from the solution as noted by the decrease in the resistivity of the outlet water—water processed by the washing systems of the present invention—and/or a decrease in the level of hardness reduction. In one embodiment, the decreased performance of the electrodes is observed by a conductivity meter. One of ordinary skill in the art would readily be able to determine means of measuring the decrease in performance of the electrodes of the present invention. The decreased performance, in one embodiment, is measured by dividing the conductivity of the “dirty” electrode—an electrode containing ionic species gathered by operation of the washing systems—by the conductivity of the “clean” electrode—electrode before the use of the washing systems, whereby clean electrode in one embodiment is substantially free of ionic species—to determine the conductivity fraction. When the conductivity fraction reaches a predetermined value, a self-cleaning cycle is initiated. In one embodiment, a self-cleaning cycle is initiated when the conductivity fraction is less than about 0.9, in another embodiment, the conductivity fraction is less than about 0.7, in yet another embodiment, the conductivity fraction is less than about 0.5, in yet another embodiment, the conductivity fraction is less than about 0.4, in yet another embodiment, the conductivity fraction is less than about 0.3, in yet another embodiment, the conductivity fraction is less than about 0.2, in yet another embodiment the conductivity fraction is between about 0.1 and about 0.6, in yet another embodiment the conductivity fraction is between about 0.2 and 0.4.
Optionally, the capacitive deionization unit further comprises a prefilter. Without wishing to be bound by theory, it is believed that the prefilter is capable of extending the life of the electrodes, as well as delaying the frequency of the self-cleaning cycle of the electrodes. It is believed that the prefilter absorbs, blocks, or otherwise removes neutrally charged species contained in feed water. Such neutrally charges species are minimally effected by the electrodes on the capacitive deionization unit and thus are capable of contaminating the adsorption sites on the electrodes. The prefilter of the present invention is made from any material that substantially absorbs, blocks, and/or otherwise removes neutrally charged species from feed water. Such materials include, but are not limited to, activated carbon, silica, paper, metallic mesh filters, membranes, gels, and combinations thereof.
Nanofiltration
In another embodiment, the water-softening zone comprises a feed water filtration device. One type of filtration device is a nanofiltration device having a cut-off in the range from about 100 to about 1000 Daltons, in one embodiment from about 200 to about 1000 Daltons. The clean water flux of the device, on the other hand, is in one embodiment at least 3, in one embodiment at least 6 L/m2h at 100 kP at 25° C. The device in one embodiment has a magnesium ion rejection of at least 50%, in one embodiment at least 80% (0.35 wt % MgSO4, 600 kP, Re=2500, 25° C.).
In yet another embodiment, the water-softening zone takes the form of a cross-flow filtration device having permeate and retentate outlet ports, the permeate outlet port being in fluid communication with the washing zone and the retentate outlet port being in fluid communication with one or more of the effluent storage, discharge and wash liquor-cleanup and recycle zones.
In still another embodiment, cross-flow devices are provided with a feed water input, retentate recirculation, hard-water effluent bleed and optional recirculation pump. In one embodiment, the flux ratio of soft-water permeate to hard-water effluent is at least about 1:1, In another embodiment at least about 3:1, in yet another embodiment at least about 5:1, and in still another embodiment at least about 8:1.
Such filtration devices in one embodiment take the form of a module comprising a filter housing provided with a membrane compartment in which is mounted a bundle of capillary or tubular filtration membranes, the ends of which are encased in membrane holders and which communicate with one or more inlet ports and one or more retentate outlet ports. The filter housing is also provided with one or more openings in the wall of the filter housing and which communicate with one or more permeate outlet ports. Hot or cold water from the feed supply enters the filter housing via a connection into the inlet port and then passes through the capillary or tubular filtration membranes, the resulting retentate and permeate being discharged through connections into the corresponding retentate and permeate outlet ports. Such an arrangement is referred to herein as an ‘inside-out’ arrangement.
Alternatively, the module can be operated in reverse manner (‘outside-in’) wherein the feed water is supplied and the retentate discharged via openings in the wall of the filter housing communicating with corresponding inlet and retentate outlet port connections. In this case permeate is collected within the filtration membranes and discharged via their open ends and corresponding permeate outlet port connections.
The module can also be provided with one or more distributor pipes placed transverse to the direction of the filtration membranes with one or more openings into the membrane compartment in order to reduce the transverse forces on the filtration membranes, such an arrangement being described in detail in WO-A-98/20962.
Exemplary filtration devices or modules include polyamide/polyethersulfone nanofiltration membranes developed for inside-out filtration marketed by X-Flow B.V. under the designation NF50M10.
Nanofiltration membranes can be prone to degradation or attack by chlorine in feed water. Accordingly the filtration device may be used in conjunction with a chlorine removal system such as a carbon prefilter, an antioxidant or brass in order to extend the working life of the device.
In filtration device embodiments, the filtration device in one embodiment also comprises a pump for recirculating the retentate stream through the filtration module under elevated pressure, the pump either being situated in the recirculation loop with the sole or primary purpose of retentate recirculation or else being operatively connected to the main discharge pump of the washing appliance or washing zone.
Electrodialysis/Electrodeionization
In yet another embodiment, the water-softening zone comprises an electrodialysis unit or electrodeionization unit. In electrodialysis, cation-exchange membranes are alternatively stacked with anion-exchange membranes and the resulting compartmentalized array is placed between two oppositely-charged electrodes. Feed water is fed into the device under low pressure and circulated between the membranes. On application of direct current to the electrodes, cations and anions move in opposite directions towards the cathode and anode respectively and concentrate in alternate compartments. The at least partially softened water resulting from the electrodialysis unit is then fed to the washing zone and the hard water effluent fed to one or more of the effluent storage, discharge and wash liquor-cleanup and recycle zones.
Electrodeionization is in effect a combination of electrodialysis with ion exchange. In this case a mixture of cation- and anion-exchange resins are introduced between the cation- and anion-exchange membranes and all ionic species in the feed water are trapped within the resin. The at least partially softened water output is then fed to the washing zone whereupon the device undergoes an electrochemical regeneration cycle in which the cation- and anion-exchange resins are regenerated for subsequent use. The resulting the hard water effluent is then fed to one or more of the effluent storage, discharge and wash liquor-cleanup and recycle zones.
Wash Liquor Cleanup
Optionally, the washing system comprises a wash liquor cleanup and recycle zone in fluid communication with the washing zone for purposes of cleaning and recycling the wash liquor from the washing zone. Cleaning of the wash liquor can be performed as a separate batch operation on bulk liquor at an off-line location, but in one embodiment cleaning is performed on a stream of the wash liquor within a recycle loop section of the washing system. Alternatively cleaning can take place within a section or sub-zone of the washing zone itself. The term ‘cleaning’ refers to a reduction in the soil content of the wash liquor (either the bulk liquor or the wash liquor stream as appropriate), soil content being measured, for example, by means of turbidity. In one embodiment the turbidity of the recycled wash liquor is less than about 15 NTU, in one embodiment less than about 5 NTU.
After cleaning, the liquor is recycled back to the washing zone where it can be used in the same or a subsequent washing step or in a post-wash rinsing step. In preferred embodiments of this type, the wash liquor is recycled to the washing zone during or at the end of an essentially detergent-free prewash step prior to a detergent-assisted, in one embodiment a bleach-assisted washing step. Prewash embodiments of the invention are particularly valuable herein in the case of bleach-assisted substrate washing steps from the viewpoint of providing improved bleaching and cleaning performance. Preferably, the washing system is arranged to provide continuous or semi-continuous cleanup and recycle of wash liquor during the same substrate washing step, in other words, the wash liquor is recycled continuously or in one or more phases of operation during the washing or prewashing step so as to remove soil from the washing zone and reduce or minimize soil redeposition onto the substrate. By ‘essentially-free’ of detergent is meant a wash liquor containing less than about 0.1% of detergent product by weight of the wash liquor.
In certain systems and methods of the invention the wash liquor cleanup and recycle zone comprises a wash liquor filtration device which is effective to lower the turbidity of the recycled wash liquor to less than about 15 NTU, in one embodiment less than about 5 NTU. The permeate flux delivered by the device, on the other hand, is in one embodiment at least about 100 L/h, in one embodiment at least about 500 L/h when operating at a pressure in the range from about 100 to about 1000 kP (1-10 bar), in one embodiment from about 100 to about 400 kP (1-4 bar). The surface area of the membrane is in one embodiment from about 0.01 to about 2 m2, in one embodiment from about 0.05 to about 1 m2, in one embodiment from about 0.25 to about 0.75 m2.
In other embodiments herein, the wash liquor cleanup and recycle zone comprises an ultrafiltration or microfiltration device. The filtration device in one embodiment has a cut-off in the range from about 1000 Daltons to about 1 μm, in one embodiment from about 0.05 μm to about 0.5 μm. The filtration device in one embodiment comprises one or more tubular membranes, the lumen size of each membrane being in one embodiment from about 1 to about 10 mm, in one embodiment from about 2 to about 6 mm, and in one embodiment from about 3 to about 5 mm. The filtration device in one embodiment has a clean water flux of at least about 1000 L/m2.h.100 kp (RO water at 25° C.), in one embodiment at least about 10,000 L/m2 at 100 kP. The cut-off herein refers to the nominal pore size rating of the membrane of the device except that the overall minimum value (1000 Daltons) is given in terms of molecular weight cut-off. Lumen size refers to the minimum internal diameter of the membrane.
In one embodiment, the system of the present invention includes a wash liquor cleanup and recycle zone that comprises a cross-flow filtration device. In one embodiment, the cross-flow filtration device comprises one or more free-standing, asymmetric, tubular filtration membranes, each tubular membrane having a lumen size having the dimensions described above. In other embodiments, the device comprises a series of intercommunicating membrane subunits, each subunit being in the form of a bundle comprising one or more, in one embodiment from about 2 to about 20, in one embodiment from about 5 to about 15 of the tubular filtration membranes. Where the device comprises a plurality of subunits in series, the individual subunits can be interconnected by one or more sections of tubular membrane having a larger lumen size. The total path length of tubular membrane in the device is in one embodiment from about 10 to about 250 m, in one embodiment from about 35 to about 150 m and the pressure drop across the cross-flow filtration device from its inlet to its outlet is less than about 2 bar, in another embodiment less than about 1 bar, and in another embodiment from about 0.2 to about 0.5 bar. Furthermore each tubular membrane in one embodiment has a Reynold's Number of at least about 2300, in another embodiment at least about 4000 at an operating pressure in the range from about 100 to about 1000 kP (1-10 bar), in another embodiment from about 100 to about 400 kP (14 bar).
The cross-flow filtration device is provided with wash liquor input and permeate and retentate outlet ports, the permeate outlet port being in fluid communication with the washing zone and the retentate outlet port being in fluid communication with a wash liquor buffer zone or with the effluent discharge zone.
In systems employing a wash liquor buffer zone, wash liquor is fed or drawn from the washing zone to the buffer zone along a first conduit and is then fed under pressure with the aid of a pump along a second conduit from the buffer zone to the inlet port of the cross-flow filtration device. A conventional coarse filter designed to remove particles of greater than about 20 microns, for example activated carbon, can also be provided upstream of the cross-flow filtration device for removal of larger size impurities. The resulting retentate is then recirculated to the buffer zone with permeate being returned to the washing zone. A pressure relief valve can also be provided on the inlet port of the cross-flow filtration device, excess pressure being relieved by drainage into the buffer zone or effluent discharge zone. In one embodiment, the buffer zone is closed to the atmosphere in which case wash liquor is automatically drawn into the buffer zone in tandem with the removal of permeate to the washing zone. Alternatively the buffer zone can be vented to atmosphere and the wash liquor fed under pressure from the washing zone to the buffer zone. Relief valves can also be positioned on the retentate outlet and on the inlet and outlet sides of the buffer zone. A valve, for example a pinch valve, can also be provided on the permeate outlet port of the filtration device to enable intermittent clean-sweeping or back-flushing of the filtration membrane. However, it is a feature of the systems of the invention that they require minimal maintenance in the form of back-flushing or defouling procedures.
The filtration device in one embodiment takes the form of a module comprising a filter housing provided with a membrane compartment in which the tubular filtration membrane or membranes are mounted, the ends of which are encased in membrane holders and communicate with the inlet and retentate outlet ports. Where the device comprises a series of intercommunicating membrane subunits, each subunit generally comprises a bundle of tubular membranes, a pair of membrane holders for encasing the ends of the tubular membranes and an outer sheath provided with one or more openings to allow discharge of permeate into the membrane compartment of the filter housing. The individual membrane subunits can intercommunicate via one or more sections of interconnecting tubular membrane having a lumen size generally greater than that of the individual subunits. The terminal subunits of the series, on the other hand, can communicate with the inlet and retentate outlet ports via one or more sections of tubular membrane and corresponding membrane holders set into the membrane housing. The filter housing is also provided with one or more openings in the wall of the filter housing communicating with the permeate outlet port or ports. Wash liquor enters the filter housing via a connection into the inlet port and then passes through the filtration membrane or membranes, the resulting retentate and permeate being discharged through connections into the corresponding retentate and permeate outlet ports.
A wide range of membrane materials can be employed herein for the ultrafiltration or microfiltration device including polypropylene, polyvinylidene difluoride, cellulose acetate, cellulose, polypropylene, polyacrylonitrile, polysulfones, polyarylsulphones, polyethersulphones, polyvinyl alcohol, polyvinyl chloride, polycarbonate, aliphatic and aromatic polyamides, polyimides and mixtures thereof. Preferred herein however is an asymmetric polyethersulphone membrane having a nominal pore size ratio (inner to outer surface) of about 1:10 and a surface energy (inner surface) of about 8 dynes/cm.
Product Dosing
In one embodiment, the washing systems of the invention comprise a dosing zone situated intermediate the water-softening zone and the washing zone. In one embodiment, the dosing zone comprises means for dosing product (either an active detergent or a detergent auxiliary such as a finishing agent or fabric enhancer) into the pre-softened feed water within or on the feed water inlet to the washing zone and may also comprise product storage means for bulk detergent and/or detergent auxiliary product. In addition, the product dispensing zone will generally comprise means enabling filling, refilling or replacement of the product storage means and may in addition comprise valves, dispensing orifices or other means for controlling the dosing rate of the detergent and/or detergent auxiliary product relative to the soft water flux of the water-softening zone. In one embodiment, the dispensing and water-softening zones are serially-connected or comprise an integral water-softening and product-dispensing unit, i.e. a unit having separate but interconnected water-softening and product-dispensing zones, the product-dispensing zone being downstream of the water-softening zone and comprising means for dosing product into the feed water on the output side of the water-softening zone.
In one embodiment the substrate is contacted with the wash liquor while simultaneously performing cleanup and recycle of the wash liquor. In such embodiments, it can be advantageous to perform cleanup and recycle in one or more phases of operation during the substrate washing step. For example, in one embodiment, cleanup and recycle is initiated in the final half of the washing step, for example, after a completion of about 50%, in one embodiment at least about 70% or even about 90% of the time for the washing step. Alternatively cleanup and recycle is initiated only after the system has reached its optimum washing temperature or after the wash liquor has reached a threshold turbidity or conductivity value or a threshold value of soil. For this purpose, the washing system can be provided with one or more sensors responsive to the turbidity, conductivity or soil level of the wash liquor and which acts as a trigger for initiating cleanup and recycle.
In another preferred embodiment which is useful for the laundering of fabrics, the wash liquor is recycled to the washing zone or rinsing zone for use in a post-wash rinsing step. Again there can also be included a recycle reservoir for storing the cleaned wash liquor prior to recycling. In one embodiment the method comprises at least one of or any combination of i) a water softening step wherein the feed water is softened in the water softening zone, ii) an optional detergent dispensing step wherein an active detergent product is dosed in a cleaning-effective amount into the wash liquor or feed water, iii) a washing step wherein the soiled substrate is contacted with the softened wash liquor, iv) the wash liquor cleanup and recycle step, v) a fabric enhancer dispensing step wherein a fabric enhancer providing a post-wash fabric care or aesthetic benefit is dosed into the recycled wash liquor, and vi) a rinsing step wherein the fabrics are contacted with the resulting rinse liquor. Suitable fabric enhancers include perfumes and other olfactory agents, textile softening agents, ironing aids, antibacterial agents, anti-pilling aids, etc.
In preferred methods of the invention, the washing step is undertaken at a detergent product wash liquor concentration in the range from about 0 to about 2% by weight, in one embodiment from about 0.01% to about 1% by weight, in one embodiment from about 0.01% to about 0.5% by weight, and in one embodiment from about 0.01% to about 0.25% by weight. Typically, however, the detergent product will be present in a cleaning-effective amount, i.e. an amount effective to improve the cleaning end-result over and above the end-result that can be achieved in the absence of detergent. Accordingly, the detergent product will normally be present in a level of at least 0.1% by weight of the wash liquor. Suitably the wash liquor pH during the washing step is in the range from about 5 to about 13, in one embodiment from about 6 to about 12, in one embodiment from about 7 to about 11. In methods comprising the use of detergency enzymes such as proteases, cellulases and amylases, the enzyme concentration during the washing step is in one embodiment from about 0.0001 to about 100 ppm of active enzyme. A non-limiting list of enzymes suitable for use herein is disclosed in, for example, US2002/0155971.
Sonics
In another application of the invention, the washing systems herein additionally comprise means for sonically or ultrasonically treating the soiled substrate in the washing zone or in a washing pre-treatment zone. In particular it has been found herein that the combination of sonic or ultrasonic treatment with wash liquor cleanup and recycle and water-softening is particularly valuable for providing improved cleaning of substrates across the range of detergent usage levels. In one embodiment the means for sonically or ultrasonically treating the soiled substrate comprises a sonic or ultrasonic energy generator or a plurality of such generators wherein the frequency of the generated energy is in the range from about 1 kHz to about 150 kHz, in one embodiment from about 20 kHz to about 80 kHz and the power input to the generator is in the range from about 0.1 W to about 500 W, in one embodiment from about 10 W to about 250 W.
In one embodiment, the energy generator is adapted for generating and supplying ultrasonic energy to the soiled substrate within the washing zone. In such an embodiment, the frequency of the generated energy is in one embodiment in the range from about 20 kHz to about 150 kHz, in one embodiment from about 20 kHz to about 80 kHz, and the power input to the generator is in one embodiment in the range from about 20 W to about 500 W per gallon of wash liquor (5.28 W to 132.1 W per litre), in one embodiment from about 25 W to about 250 W per gallon of wash liquor (6.6 W to 66.1 W per litre) in the washing zone. An energy generator suitable for use in such embodiments comprises an ultrasound transducer and an electronic power supply. The ultrasound transducer can be either a PZT (Lead-Zirconate-Titanite) transducer or a magnetostrictive transducer. Examples of the commercial ultrasound transducers include Vibra-Cell VCX series from Sonics & Materials Inc, and Tube Resonator from Telsonic AG. Single or array of several transducers can be used in the washing system. The transducer(s) can be mounted at the bottom or on the sidewall surrounding the washing zone. It can also be submersed directly in the washing zone. The transducers can also be mounted within the washing machine drum or tub as described in detail below.
In a preferred embodiment of this type, the washing system takes the form of a front-loading washing machine comprising a drum for accommodating the laundry, the drum having one or more, in one embodiment two to four, in one embodiment three baffles on the inner circumferential wall thereof for tumbling the laundry. The washing machine also comprises one or more sonic or ultrasonic generators mounted on at least one and in one embodiment on each baffle of the drum so that sonic or ultrasonic energy is applied to the laundry as the laundry items are lifted out of the bulk wash liquor in contact with the corresponding baffle. In another embodiment of this type, the washing system takes the form of a top-loading washing machine having a central agitator paddle having one or more sonic or ultrasonic generators mounted thereon.
In an alternative embodiment, the energy generator is adapted for generating and supplying sonic or ultrasonic energy to the soiled substrate within the washing pre-treatment zone. In such an embodiment, the frequency of the generated energy is in one embodiment in the range from about 1 kHz to about 80 kHz, in one embodiment from about 20 kHz to about 60 kHz, and the power input to the generator is in one embodiment in the range from about 0.1 W to about 80 W, in one embodiment from about 1 W to about 40 W. An energy generator suitable for use in such embodiments comprises one or more vibrating cleaning transducers adapted to physically contact one or more surfaces of the soiled substrate. In use, the soiled substrate is passed under or between the cleaning transducers, the substrate being simultaneously or previously wetted with wash liquor. The cleaning transducer can be mounted in a convenient position outside the washing zone and provided with means to enable drainage of the wash liquor into the washing zone.
The systems and methods of the invention can also include embodiments that combine the energy generator for the washing zone and the energy generator for the washing pre-treatment zone with frequencies and power inputs as described above.
Electrolysis Zone
In a further application of the invention, the washing systems herein additionally comprise an electrolysis zone for electrolysing the feed water or wash liquor for purposes of generating electrolytically-activated wash liquor and/or rinse liquor. In particular it has been found herein that the combination of electrolysis with wash liquor cleanup and recycle and water-softening is particularly valuable for providing improved cleaning of substrates across the range of detergent usage levels. The electrolysis zone herein in one embodiment comprises electrolysis means provided with at least a pair of electrodes for electrolysing the feed water or wash liquor, the electrolysis means being referred to respectively as feed water electrolysis means and wash water electrolysis means. Generally the feed water electrolysis means is disposed intermediate the feed supply and washing zone, while the wash liquor electrolysis means is disposed within the washing zone or within the wash liquor recycle zone. A combination of feed water and wash liquor electrolysis means is also envisaged herein. Optionally, the electrolysis zone can also comprise a reservoir (the electrolysis reservoir) for storage of the resulting electrolysed water, and means for storage and dispensing of electrolyte or other oxidant-precursor species into the feed water or wash liquor.
In terms of function, electrolysis zones suitable for use herein include both oxidant-generating and pH-generating electrolysis zones. In oxidant-generating embodiments of the invention, the feed water or wash liquor comprises in use one or more oxidant-precursor species and the electrolysis zone comprises means for generating one or more streams of oxidant or mixed-oxidant species in the feed water or wash liquor by electrolysis of the oxidant-precursor species.
In pH-generating embodiments of the invention, the electrolysis zone comprises means for generating one or more streams of acidic and/or alkaline species in the feed water or wash liquor, said one or more streams being supplied to the washing zone for use in the substrate washing step or in a subsequent substrate rinsing step.
By ‘electrolytically-activated wash liquor’ is meant wash liquor that has been subjected to electrolysis, e.g. to generate oxidant, mixed oxidant, acidic or alkaline species, or wash liquor derived from feed water that has been subjected to electrolysis. The term ‘electrolytically-activated rinse liquor’ on the other hand refers to rinse liquor derived from feed water or wash liquor that has been subjected to electrolysis.
In one embodiment, the electrolysis unit is utilized in combination with the capacitive deionization unit to generate bleaching species capable for use as stain removers and for sanitization. In such an embodiment, the waste stream from the capacitive deionization unit is routed to the electrolysis unit. Without wishing to be bound by theory, it is believed that the waste stream from the capacitive deionization unit contains a high level of cationic and/or anionic species. The cationic and/or anionic species within the waste stream, upon electrolysis, are converted to various bleaching species including, but not limited to, hypochlorite, chlorine dioxide, and combinations thereof. It is believed that the majority of bleaching species are in the base stream. The bleaching species generated are routed to the washing zone. Without wishing to be bound by theory, it is believed that the acid stream, when sent to the washing zone, in the washing zone acts as an antimicrobial in the washing zone. Further, it is believed that the base stream, when sent to the washing zone, acts to raise the pH to improve cleaning. Further the acid stream and/or base stream could be recombined and still deliver a bleaching effect in the wash zone or the one or both streams could be sent to the waste.
In another embodiment, the acid stream and/or the base stream from the electrolysis unit is used to clean and/or regenerate the electrodes and/or other units. In such an embodiment, the electrolysis unit is used to generate an acid stream and/or a base stream. Without wishing to be bound by theory, it is believed that any metal species located on the electrodes will react when contacted by the acid stream while any neutral organic species will react when contacted by the base stream. After contact with the acid and/or the base stream, the neutral metal species and/or the neutral organic species become soluble. Upon solublization, the reacted neutral metal species and the neutral organic species optionally can be expelled as a waste electrode stream out of the capacitive deionization unit.
In yet another embodiment, the acid stream and/or the base stream can be used to clean various units in connection with the current invention. In one non-limiting example, the acid stream and/or the base stream is used to clean a cross-filtration unit. Without wishing to be bound by theory, the acid stream and/or the base stream is brought into contact with the surface of the membranes of the cross flow filtration unit. Upon contact, the acid stream and/or the base stream reacts and/or dissolves species located on the membrane, thus providing cleaning.
In one embodiment, an electrolysis brine is added to the water before electrolysis. Without wishing to be bound by theory, it is believed that the addition of the electrolysis brine to the water before electrolysis facilitates in the production of bleaching species, including HClO−. In one embodiment, the electrolysis brine comprises sodium chloride and water. The percentage by weight of sodium chloride in water for the electrolysis brine is from about 0.1% to about 35.9%, in another embodiment from about 1% to about 30%, in another embodiment from about 4% to about 20%, in another embodiment from about 5% to about 10%. The electrolysis brine is added to the softened water such that, in the wash zone, a percentage by volume concentration of electrolysis brine to softened water is from about 0.1% to about to 20%, in another embodiment from about 1% to about 10%, in another embodiment from about 2% to about 7%, in another embodiment, from about 3% to about 6%, in another embodiment from about 1% to about 4%.
Disinfection Zone
In another application of the invention, the washing systems herein additionally comprise a wash liquor disinfection zone. In particular it has been found herein that the combination of wash liquor disinfection with wash liquor cleanup and recycle and water-softening is particularly valuable for providing improved cleaning of substrates across the range of detergent usage levels.
The disinfection zone can take a number of different forms. In a first embodiment, the disinfection zone comprises an antibacterial agent (which term herein includes both bactericidal and bacteriostatic agents) and means for delivering the antibacterial agent to the wash liquor. In one embodiment the antibacterial agent comprises one or more oxidant or bleaching species such as ozone, hypochlorous acid or one or more antibacterial metal ion sources inclusive of silver, copper, zinc, tin and compounds thereof as well as combinations of said antibacterial ion sources with inorganic carrier materials. In a preferred embodiment of this type, the disinfection zone comprises an electrolytic source of an antibacterial agent such as silver, copper, zinc or tin ions or of an active oxidant or bleaching species such as hypochlorous acid. In another embodiment, the disinfection zone comprises a photocatalyst and/or UV source. In such embodiments, the photocatalyst and/or UV source can be associated with an ultrafiltration or microfiltration device for purposes of cleaning and disinfecting both the filtration device and the wash liquor.
EXAMPLE
All documents cited in the Detailed Description of the Invention are, are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims
1. A washing system for cleaning within a washing zone comprising:
- a. at least one inlet capable of fluid communication with a feed water;
- b. at least one treatment zone in fluid communication with the at least one inlet, said at least one treatment zone comprising a water softening zone, an electrolysis zone, a dosing zone and combinations thereof; and
- c. at least one outlet in fluid communication the at least treatment zone capable of being in fluid communication with a washing zone.
2. The washing system of claim 1, wherein the washing zone is capable of cleaning or washing substrates comprises laundry and dishware.
3. The washing system of claim 1, wherein the water softening zone comprises nanofiltration devices, electrodeionization devices, electrodialysis devices, reverse-osmosis devices capacitive deionization devices, flow-through capacitors and ion-exchange water-softening devices and combinations thereof.
4. The washing system of claim 3, wherein the water-softening zone comprises capacitive deionization.
5. The washing system of claim 1, wherein the at least partially softened water comprises a conductivity of 100 μS/cm or less.
6. The washing system of claim 1, wherein at least partially softened water comprises a soft water flux of at least about 2 L/h at a feed water pressure from about 100 to about 1000 kP.
7. The washing system of claim 1, wherein the device and the washing zone are housed substantially within one housing.
8. The washing system of claim 1, wherein the device and the washing zone are independently housed.
9. The washing system of claim 1, wherein the dosing zone is fluidly connected between the at least one inlet and at least one outlet and capable of dispensing a fabric care composition.
10. The washing system of claim 9, further comprising a mixing zone functionally connected between the dosing zone and the outlet capable of at least partially mixing the fabric care composition with a second fluid.
11. The washing system of claim 10, wherein the mixing zone comprises in-line mixers comprising, venturi flow, direct injection pumps, peristaltic pumps, gravity feeds, and spraying; sonic mixers; ultrasonic mixers; and combinations thereof.
12. The washing system of claim 9, wherein from about 0.01 to about 50 grams of fabric care composition are dispensed by the dosing zone.
13. The washing system of claim 1, comprising at least one water softening zone and at least one electrolysis zone.
14. The washing system of claim 13, comprising:
- a. a first water softening and a second water softening zone; and
- b. a first electrolysis zone and a second electrolysis zones
- wherein the first water softening zone is fluidly connected to the first electrolysis zone and the second water softening zone is fluidly connected to the second electrolysis zone.
15. The washing system of claim 1 further comprising at least one check valve between the at least one inlet and the at least one outlet.
16. The washing system of claim 1, further comprising at least one sensor capable of sensing at least one water level, density, conductivity, pH, vibration, temperature, turbidity, viscosity, and combinations thereof.
Type: Application
Filed: May 17, 2005
Publication Date: Nov 17, 2005
Applicant: The Procter & Gamble Company (Cincinnati, OH)
Inventors: Paul Vernon (West Chester, OH), Mark Glogowski (Cleves, OH), John Haught (West Chester, OH), Robb Gardner (Cincinnati, OH), Adam Costello (North Tyneside), Andre Baeck (Bonheiden), Andre Convents (Diegem), Johan Smets (Lubbeek), Pascale Van Steenwinckel (Weerde), Peter Gray (Brussels), Graeme Cruickshank (Newcastle upon Tyne), Michael Duncan (Northumberland)
Application Number: 11/130,713
