METHOD AND APPARATUS FOR THE WET TREATMENT OF LAUNDRY ARTICLES

Abstract

In the washing and drainage of laundry articles, treatment liquid which contains still unspent wash-active substances occurs at the end of the washing operation. These substances have hitherto been conducted, if appropriate after neutralization, into the discharge together with the treatment liquid. This known procedure has an adverse effect on the efficiency of the washing operation. According to the invention, spent wash-active substances are removed from the treatment liquid separated from the laundry articles after the washing operation. This takes place by means of precision filtration, in which only the spent wash-active substances which are larger due to the absorption of dirt from the washing operation are filtered out of the treatment liquid, but not the unspent wash-active substances having a smaller particle size. These can be reused, together with the treatment liquid, for a subsequent washing operation.

Description

STATEMENT OF RELATED APPLICATIONS

This patent application is based on and claims convention priority on German Patent Application No. 10 2007 019 193.8 having a filing date of 20 Apr. 2007, which is incorporated herein by this reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to methods for the wet treatment of laundry articles, in particular for the at least washing, of laundry articles, the laundry articles being at least washed in a treatment liquid containing at least one wash-active substance, and thereafter the treatment liquid being at least partially separated from the treated laundry articles. The invention relates, furthermore, to apparatuses for the wet treatment of laundry articles, in particular for the at least washing of laundry articles, with a washing machine having a drum drivable in rotation and with a drainage device following the washing machine.

2. Prior Art

In the wet treatment, in particular washing, of laundry articles, which may be all types of articles to be washed, treatment liquid containing wash-active substances are used. After washing, the treatment liquid not bound in the laundry articles, what is known as the free liquor, is separated from the laundry articles. The treatment liquid then contains spent wash-active substances which have absorbed the dirt from the laundry articles, but also still unspent wash-active substances.

It has hitherto been customary to discharge the used treatment of liquid at least partially as sewage. The unspent wash-active substances are consequently lost. Depending on the type of wash-active substances, it may be necessary to neutralize them before they are discharged into, for example, a sewage conduit. Finally, the discharge of the used treatment liquid makes it necessary to employ fresh water again for the next washing operation. For the reasons mentioned, the previous discharge of the used treatment liquid is inefficient.

BRIEF SUMMARY OF THE INVENTION

Proceeding from the above, the object on which the invention is based is to provide methods and apparatuses for the wet treatment of laundry, which have higher efficiency, as compared with known methods and apparatuses.

A method for achieving this object is a method for the wet treatment, in particular for the at least washing, of laundry articles, the laundry articles being at least washed in a treatment liquid containing at least one wash-active substance, and thereafter the treatment liquid being at least partially separated from the treated laundry articles, characterized in that spent wash-active substances are removed at least for the most part from the treatment liquid separated from the laundry articles. Accordingly, spent wash-active substances are removed from the treatment liquid separated from the laundry articles. The spent wash-active substances bind the dirt which the treatment liquid has entrained from the previous washing operation. Thus, by the spent wash-active substances being removed, the dirt is removed at least for the most part from the treatment liquid. The treatment liquid having the remaining unspent wash-active substances can then be reused for a subsequent washing operation. As a result, unspent wash-active substances are not lost, and they do not have to be neutralized even for the discharge of the treatment liquid into the sewage system. Above all, by virtue of the method according to the invention, the consumption of fresh water can be reduced, because the treatment liquid, together with the unspent wash-active substances, can be implemented anew for washing the laundry articles.

There is provision, furthermore, for removing the spent wash-active substances from the treatment liquid after various treatment steps of the laundry articles, for example after the pre-wash and after the clear wash. Thus, the entire treatment liquid occurring during a multi-stage washing operation, together with the wash-active substances still contained in it, can be reused.

According to a further preferred refinement of the method, there is provision for removing the spent wash-active substances from the treatment liquid a plurality of times. Preferably, during the rinsing of the washed laundry articles in a drainage device, there is provision for removing spent wash-active substances from the treatment liquid separated from the laundry articles after washing and also from the treatment liquid separated from the drainage device before rinsing in the drainage device. This two-stage removal of the spent wash-active substances from the treatment liquid optimally makes available treatment liquid freed of spent wash-active substances and containing essentially only unspent wash-active substances present in it, for a subsequent washing operation, specifically, in particular, for a washing operation with a separate pre-wash and clear wash. The fresh-water requirement therefore amounts to only a fraction of the treatment liquid required for the subsequent washing operation, and, if necessary, only the wash-active substances actually spent have to be replaced.

In the preferred method, the spent wash-active substances are separated from the treatment liquid by filtration, preferably precision filtration. Since, due to dirt absorption, spent wash-active substances have a particle size which overshoots the particle size of unspent wash-active substances, separation between the unspent and the spent wash-active substances can take place by filtration. Since the particle sizes differ from one another only slightly, above all lie only in the micrometer range, precision filtration is suitable particularly for the effective removal of at least a large part of the spent wash-active substances from the treatment liquid.

An advantageous development of the method provides for carrying out pre-filtration before spent wash-active substances are filtered out of the treatment liquid. During this pre-filtration, larger dirt particles are eliminated which, during the subsequent filtering-out of spent wash-active substances, in particular by precision filtration, can no longer have a disturbing effect by loading or even clogging the sensitive filters for precision filtration. After pre-filtration, therefore, a particularly effective and reliable filtration of at least a large part of the smaller spent wash-active substances is possible.

The removal of spent wash-active substances from the treatment liquid expediently takes place by means of micro- and/or ultra-filtration. Spent wash-active substances can thereby be removed from the treatment liquid in a directed manner. These are preferably particles with a size of between 10 μm and 0.005 μm, preferably 1 μm to 0.5 μm. This is the typical particle size of spent wash-active substances, so that at least a large part of the spent wash-active substances is removed in this way, but not the smaller unspent wash-active substances.

A further method for achieving the object mentioned in the introduction, which may also be a preferred development of the method described above, is a method for the wet treatment, in particular for the at least washing, of laundry articles, the laundry articles being at least washed in a treatment liquid containing at least one wash-active substance, and thereafter the treatment liquid being separated at least partially from the laundry articles, characterized in that, during treatment, the content of the at least one wash-active substance still contained in the treatment liquid is determined. Accordingly, there is provision, after the removal of spent wash-active substances from the treatment liquid, for determining the content of the spent wash-active substances still contained in it. This may take place, for example, by means of what is known as a bubble tensometer, for example an H₂O₂ sensor or a Cl sensor. Other measuring methods or sensors suitable for the particle size of unspent wash-active substances may also be considered.

A further refinement of the method provides for comparing the measured content of the unspent wash-active substances still present in the treatment liquid with a desired content of wash-active substances in the treatment liquid. If it is in this case established that the measured content of the unspent wash-active substances still contained in the treatment liquid lies below the desired content, fresh wash-active substances are added to the treatment liquid in a directed manner. This secondary metering takes place to an extent such that the treatment liquid again has a content of unspent wash-active substances which corresponds to the desired content of unspent wash-active substances in the treatment liquid or lies somewhat above it, preferably within an excess range selected in a directed manner.

An apparatus for achieving the object mentioned in the introduction, having a washing machine, in particular continuous-flow washing machine, having a drum drivable in rotation, and a drainage device, for example a drainage press or a laundry centrifuge, is an apparatus for the wet treatment of laundry articles, in particular for the at least washing of laundry articles, with a washing machine having a drum drivable in rotation and with a drainage device following the washing machine, characterized in that at least one filter for removing at least one spent wash-active substance in the treatment liquid is assigned to an outflow line, returned to the start of a washing zone for the treatment liquid from the drum and to an outflow line, returned to the start of the washing zone from the drainage device. Accordingly, there is provision for assigning a filter for the removal of spent wash-active substances from the treatment liquid in each case to an outflow line, returned to the drum, for the treatment liquid from the drum and to an outflow line, returned to the drum, for the treatment liquid from the drainage device. Thus, the spent wash-active substances are to be filtered out wherever used treatment liquid not found in laundry articles and having both unspent and spent wash-active substances occurs. As a result, both the treatment liquid discharged in the washing machine and the treatment liquid occurring in the region of the drainage press are prepared for reuse. Since the treatment liquid from the washing machine and from the drainage device is prepared, prepared treatment liquid without spent wash-active substances occurs at various points and can be supplied again to different points in the washing machine in a directed manner, in particular to the pre-wash and clear wash. The invention is therefore suitable particularly for apparatuses for the washing, rinsing and drainage of laundry articles in which rinsing takes place in the drainage device.

A further apparatus for the at least washing of laundry articles, which serves for achieving the object mentioned in the introduction, is an apparatus for the wet treatment of laundry articles, in particular for the at least washing of laundry articles, with a washing machine having a drum drivable in rotation and with a drainage device following the washing machine, characterized in that at least one filter for the removal of at least one spent wash-active substance from the treatment liquid is assigned to at least one outflow line, returned to the start of the washing zone for treatment liquid from the drum. In this apparatus, there is provision for assigning a filter for the removal of spent wash-active substances from the treatment liquid to at least one outflow line, returned to the start of the drum, for the treatment liquid from the drum. Thus, the entire treatment liquid which occurs during the washing of the laundry articles can be freed of spent wash-active substances before the rinsing of the laundry articles. Preferably, treatment liquid occurs after the pre-wash and the clear wash. The spent wash-active substances are then removed from these separately occurring treatment liquids before the treatment liquid is employed anew for washing. The treatment liquids freed at least for the most part of spent wash-active substances can be supplied, as required, to the laundry articles before the pre-wash and/or before the clear wash. For example, the treatment liquid, having higher temperatures, from the preceding clear wash can be supplied with a renewed clear wash after the separation of spent wash-active substances, while the treatment liquid from the pre-wash is supplied for the pre-wash again. Thus, no appreciable energy needs to be supplied to the respective treatment liquids in order to use them again. In particular, the cold treatment liquid from the pre-wash does not have to be heated in order to be supplied to the clear-wash.

In a preferred refinement of the apparatus, filters for the separation of spent wash-active substances from the treatment liquid are used, which are designed as micro- and/or ultra-filters. Above all, membrane filters may be considered as such filters. These membrane filters are preferably provided with supporting bodies, and these may be ceramic supporting bodies. The filters may be designed as what are known as cross-flow filters or as dead-end filters.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the invention are explained in more detail below with reference to the drawing in which:

FIG. 1 shows a diagrammatic side view of the apparatus according to a first exemplary embodiment of the invention.

FIG. 2 shows a diagrammatic side view of the apparatus according to a second exemplary embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatuses shown here form a washing line for the wet treatment of laundry articles. The wet treatment is washing, rinsing and drainage. All textile articles normally to be washed are considered as laundry articles, specifically, in particular, clothing, including occupational clothing, table laundry, bed laundry, foot mats, entry mats and the like.

The apparatuses illustrated in the figures have a continuous-flow washing machine and a drainage device. The drainage device may be a centrifuge or a drainage press shown in the figures.

The continuous-flow washing machine 10 of FIG. 1 has a cylindrical drum 13 driveable in rotation about a preferably horizontal axis of rotation 12. In the drum 13, a plurality of chambers 16 succeeding one another in the flow direction 15 of the laundry articles, not shown, through the drum 13 are formed by transversely directed partitions 14.

In the drum 13 of the continuous-flow washing machine 10 of the exemplary embodiment of FIG. 1, essentially three treatment zones are located, specifically a pre-washing zone 17, a following clear-washing zone 18 and, finally, a rinsing zone 19 arranged at the end of the drum 13. In the continuous-flow washing machine 10 of FIG. 1, both the pre-washing zone 17 and the clear-washing zone 18 have two successive chambers 16. By contrast, the rinsing zone 19 has only a single chamber 16. Overall, therefore, the continuous-flow washing machine 10 has five chambers 16. However, the invention is not restricted to this. Instead, the number of chambers 16 may deviate from the exemplary embodiment shown. Above all, the pre-washing zone 17, the clear-washing zone 18 and the rinsing zone 19 may have a larger or smaller number of chambers than illustrated in FIG. 1.

The continuous-flow washing machine 10 is arranged downstream of the drainage press 16, as seen in the flow direction 15. The wash and rinsed laundry articles pass out of the continuous-flow washing machine 10 via the unloading chute 20, arranged at the end of the latter, into the drainage press 11. The drainage press 11 is designed in a basically known way. Thus, the drainage press 11 has a press housing open at the top and at the bottom, preferably a cylindrical press basket 21 with a liquid-impermeable cylindrical surface area, and a press plunger 22 which is movable up and down in the press basket 21 and which is illustrated merely in passing (by dashes) in FIG. 1. The press plunger 22 can be moved up by means of a hydraulic cylinder to an extent such that, particularly for loading the drainage press 11, it is located above the press basket 21 and consequently completely releases an upper orifice of the press basket 21. To drain the laundry articles, the press plunger 22 can be pressed into the press basket 21, the press plunger 22 being sealed off, essentially liquid-tight, inside the surface area of the press basket 21. Below the press basket 21 is located a collecting tank 23 or another device for intercepting the treatment liquid pressed out of the laundry articles.

An outflow line 24 branches off from the end of the pre-washing zone 17. The outflow line 24 leads to a pre-filter 25 and from this to a filter 26 for separating spent wash-active substances from the treatment liquid discharged out of the pre-washing zone 17 through the outflow line 24. The outflow line 24 issues from the filter 26 into a branch point 27. A return line 28 leads from the branch point 27 to the start of the continuous-flow washing machine 10, to be precise, in the exemplary embodiment shown, to an inflow funnel 29, by means of which the laundry articles to be washed can be supplied to the drum 13.

At the end of the clear-washing zone 18 is arranged a further outflow line 30 which again leads to a pre-filter 31 and thereafter to a filter 32 for separating spent wash-active substances from the treatment liquid. The outflow line 30 leads from the filter 32 further on to a branch point 33. The filtered treatment liquid, together with remaining unspent wash-active substances, but filtered-off spent wash-active substances, can be supplied from the branch point 33 via a connecting line 34 to the branch point 27, from where the filtered treatment liquid coming from the clear-washing zone 18 can be supplied via the return line 28 to the inflow funnel 29 upstream of the drum 13 of the continuous-flow washing machine 10.

A second line, to be precise a return line 35, branches off from the filter 32. This return line 35 leads via a further branch point 36 to the return line 37, from which the filtered treatment liquid, without spent wash-active substances, but still with a residue of unspent wash-active substances, can be returned to the start of the clear-washing zone 18.

The rinsing zone 19 has an overflow 38 which leads to a collecting tank 39. An intermediate line 40 branches off from the collecting tank 39 and leads to the branch point 36 in the return line 37.

Two return lines 41 and 42 branch off from the collecting tank 23 of the drainage press 11. The return line 41 leads to the branch point 33, from where the treatment liquid can be supplied from the collecting tank 23 to the inflow funnel 29 upstream of the drum 13. The return line 42 from the collecting tank 23 is led back to the rinsing zone 19, that is to say to the last chamber 16 of the continuous-flow washing machine 10.

The filters 26 and 32 are designed in a special way. These may be the same filters which allow a precision filtration of the treatment liquid originating from the pre-washing zone 17 and the clear-washing zone 18. This treatment liquid is washing water which is enriched with wash-active substances, some of which are spent as a result of dirt absorption, while some excess wash-active substances are still unspent even after the pre-wash and clear-wash. The filters 26 and 32 separate only spent wash-active substances from the treatment liquid, but no unspent wash-active substances having a lower particle size. For this purpose, the filters 26 and 32 are designed as micro- and/or ultra-filters which are suitable for filtering out particles of the size of the spent wash-active substances from the liquid. Such filters 26 and 32 make it possible to filter out from the treatment liquid particles with a size of 0.005 μm to 10 μm, preferably 0.5 μm to 1 μm.

The filters 26 and 32 are preferably membrane filters. However, other filters may also be considered which are suitable for carrying out precision filtration, above all micro- and/or ultra-filtration, in particular for filtering out particles of the abovementioned size ranges from the treatment liquid. The membrane filters are preferably designed as wound filters and/or are provided with supporting bodies. The supporting bodies are primarily ceramic supporting bodies.

The filters 26 and 32 may operate according to the cross-flow principle, but also according to the dead-end principle.

The method according to the invention proceeds, by means of the above-described apparatus according to FIG. 1, as follows:

The laundry articles to be washed pass via the inflow funnel 29 into the entry-side end of the drum 13 of the continuous-flow washing machine 10. The laundry articles are in this case flushed through with filtered treatment liquid both from the pre-washing zone 17 and the clear-washing zone 18 and from the drainage press 11. The treatment liquid is, as a rule, water which has a certain content of wash-active substances, as a rule washing agents, surfactants and the like. The dirt occurring particularly during the washing of the laundry articles is bound by the wash-active substances, with the result that these increase in size. Such wash-active substances are spent as a result of the binding of dirt. The water for forming the treatment liquid usually contains excess wash-active substances, so that, after the washing of the laundry, the treatment liquid contains not only spent wash-active substances which have bound the dirt, but also still unspent wash-active substances.

After the pre-wash of the laundry articles, at the end of the pre-washing zone 17 the treatment liquid is first pre-filtered at the pre-filter 25 by the outflow line 24. In this case, particles which are larger than the particles of spent and unspent wash-active substances are removed. Subsequently, the treatment liquid is freed in the filter 26, at least for the most part, of spent wash-active substances which are enriched with dirt from the pre-washing zone 17. Only spent wash-active substances are separated from the treatment liquid in the filter 26, but no unspent wash-active substances. Since the unspent wash-active substances have not absorbed any dirt and therefore are smaller than the spent wash-active substances, the filter 26 leaves the still unspent wash-active substances in the treatment liquid. The larger particles filtered off by the pre-filter 25 and the spent wash-active substances separated from the treatment liquid by the filter 26 are discharged respectively at the pre-filter 25 and at the filter 26. Treatment liquid containing only or essentially only still unspent wash-active substances leaves the filter 26. This treatment liquid is supplied via the branch point 27 and the return line 28 to the inflow funnel 29 upstream of the continuous-flow washing machine 10, in order to flush through laundry articles which are to be washed by the continuous-flow washing machine 10 in the next washing cycle.

The treatment liquid is separated from the washed laundry articles also at the end of the clear-washing zone 18. This treatment liquid passes via the outflow line 30 to the filter 31 and thereafter to the filter 32. At the pre-filter 31, in the same way as at the pre-filter 25, larger particles are filtered off as spent wash-active substances, while the filter 32, again in the same way as the filter 26, separates spent wash-active substances from the treatment liquid. Treatment liquid leaving this filter 32 and having essentially only unspent wash-active substances passes, as required, either via the branch point 33, the connecting line 34 and the return line 28 to the inflow funnel 29 upstream of the drum 13 or via the return line 35, the branch point 36 and the return line 37 to the start of the clear-washing zone 18. By means of a corresponding valve, not shown, and a control assigned to the latter, treatment liquid containing essentially only unspent wash-active substances is conducted in a directed manner to the inflow funnel 29 or to the start of the clear-washing zone 18.

Excess rinsing liquid passes from the overflow 38 of the rinsing zone 19 into the collecting tank 39. The rinsing water may be conducted from the collecting tank 39, as required, via the intermediate line 40 and the branch point 36 through the return line 37 to the start of the clear-washing zone 18.

Rinsing liquid pressed out by the drainage press 11 passes from the collecting tank 23 of the drainage press 11 either via the return line 41 to the branch point 33 and from there via the connecting line 34, the branch point 27 and the return line 28 to the inflow funnel 29 upstream of the drum 13 or via the return line 42 back to the rinsing zone 19. The rinsing water from the collecting tank 23 below the drainage press 11 may be conducted, as required, either to the inflow funnel 29 or to the rinsing zone 19 by means of corresponding valves, not shown.

The method described makes it possible for treatment liquid freed of spent wash-active substances, in particular spent surfactants, to be returned from the pre-washing zone 17 and the clear-washing zone 18 to the inflow funnel 29 upstream of the continuous-flow washing machine 10, so that this treatment liquid freed of spent wash-active substances can be reused for washing a subsequent batch of laundry articles.

According to a method which constitutes a specific invention and which preferably advantageously supplements the method described above, unspent wash-active substances in the filtered treatment liquid are measured during the operation of the apparatus, preferably continuously, for example by means of a bubble tensometer, an H₂O₂ sensor, a Cl sensor or the like. The measured concentration of unspent wash-active substances is then compared with a desired concentration of wash-active substances in the treatment liquid. If it is established from this comparison that the concentration of the remaining wash-active substances still present in the treatment liquid lies below the desired concentration, fresh wash-active substances are admixed to the treatment liquid, specifically preferably in the region of the return line 28. This admixing of new wash-active substances takes place to the extent such that the desired concentration of wash-active substances is produced again in the returned treatment liquid or is overshot preferably within a defined range.

By virtue of the methods according to the invention, still unspent wash-active substances in the treatment liquid are not lost; instead, they can be spent virtually completely. Consequently, no treatment liquid with unspent wash-active substances is conducted into the discharge. Above all, remaining wash-active substances in the treatment liquid do not need to be neutralized before being led away into the discharge. Moreover, the fresh-water requirement can be lowered considerably due to the reuse of the treatment liquid still containing a residue of unspent wash-active substances. Since the fresh-water requirement is thus reduced as a result of the methods according to the invention and all unspent wash-active substances are fully utilized, the efficiency of the washing process is markedly increased.

FIG. 2 shows an apparatus according to a second exemplary embodiment of the invention. This apparatus also has a continuous-flow washing machine 45 and a drainage press 46 or another drainage device, for example a laundry centrifuge. The continuous-flow washing machine 45 is designed, in principle, in the same way as the continuous-flow washing machine 10. The same reference numerals are therefore used for identical parts. In the exemplary embodiment shown, the continuous-flow washing machine 45 also has five chambers 16 succeeding one another in the flow direction 15. However, the five chambers 16 in the continuous-flow washing machine 45 form only a pre-washing zone 47 consisting of two chambers 16 and a clear-washing zone 48 consisting of three chambers 16. However, the number of chambers of the pre-washing zone 47 and of the clear-washing zone 48 may deviate from the exemplary embodiment shown, to be precise may be both larger and smaller. As a rule, however, the clear-washing zone 48 has a larger number of chambers than the pre-washing zone 47.

The continuous-flow washing machine 45 has no rinsing zone. Rinsing therefore does not take place in the continuous-flow washing machine 45. Instead, in the apparatus shown here, rinsing takes place in the drainage device, that is to say, in the exemplary embodiment shown, in the draining press 46. This therefore has two functions, to be precise serves for separating a larger part of the treatment liquid (clear-washing liquid) from the clear-washing zone 48 of the continuous-flow washing machine 45 and for the subsequent rinsing of the laundry articles, for which purpose fresh water can be supplied to the drainage press 46 via a supply line 49 shown merely in passing in FIG. 2.

The continuous-flow washing machine 45 has at the end of the pre-washing zone 47 an outflow line 50 which leads to a pre-filter 51 and from this to a filter 52 serving particularly for precision filtration. The pre-filter 51 and the filter 52 are designed in the same way as the pre-filters 25 and 31 and the filters 26 and 32 of the first exemplary embodiment and have the same purpose. The treatment liquid coming from the pre-washing zone 17 and freed of spent wash-active substances passes from the filter 52 via a branch point 53 to the return line 54 which leads to the inflow funnel 29 upstream of the continuous-flow washing machine 45.

An outflow line 55 runs from the collecting tank 23 below the drainage press 46 to a pre-filter 56 and to a following filter 57. The pre-filter 56 and the filter 57 are designed in the same way as the pre-filter 51 and the filter 52, to be precise serve first for separating coarser particles from the treatment liquid and then separating spent wash-active substances. The treatment liquid freed at least for the most part of spent wash-active substances can pass from the filter 57 via a connecting line 58 and a branch point 59 to the branch point 53 and from there via the return line 54 to the inflow funnel 29 of the continuous-flow washing machine 45. Furthermore, an outflow line 60 emanates from the filter 57 and is led back to the start of the pre-washing zone 17. By means of valves assigned to the connecting line 58 and to the outflow line 60 at the outlet of the filter 57, the liquid freed of spent wash-active substances can be conducted via a corresponding control either upstream of the continuous-flow washing machine 45 or to the start of the pre-washing zone 47.

A second connecting line 61 branches off from the collecting tank 23 below the drainage press 46 and leads to the branch point 59 and from there via the branch point 53 and the return line 54 to the inflow funnel 29 upstream of the continuous-flow washing machine 54. The connecting lines 58 and 61 of the collecting tank 23 are also provided with valves, with the result that the outflow of treatment liquid from the collecting tank 23 can be controlled in a directed manner, so that the treatment liquid can pass out of the collecting tank 23, even bypassing the pre-filter 56 and the filter 57, to upstream of the continuous-flow washing machine 45.

The method according to the invention is described in more detail below with reference to the continuous-flow washing machine 45 and to the drainage press 46 following the latter.

The pre-filters 51 and 56 and the filters 52 and 57 serving for precision filtration have the same function as the pre-filters 25 and 31 and filters 26 and 32 in the method described further above in connection with FIG. 1. Accordingly, the pre-filters 51 and 56 serve for separating larger particles from the treatment liquid before the smaller spent wash-active substances, but not the even smaller unspent wash-active substances, are separated at least for the most part from the treatment liquid by the filters 52 and 57.

The liquid prepared by the pre-filter 51 and by the filter 52 and coming from the end of the pre-washing zone 17 passes via the return line 54 to the inflow funnel 29 upstream of the continuous-flow washing machine 45. This treatment liquid containing essentially only unspent wash-active substances is used for flushing through laundry articles which are to be treated in a next washing cycle.

The washed laundry articles pass out of the clear-washing zone 48 of the continuous-flow washing machine 45 into the drainage press 46 downstream of the continuous-flow washing machine 45 or into another drainage device. The treatment liquid from the clear-washing zone 48 is first separated by the drainage press 46 from the laundry articles, with the exception of the residual moisture. The treatment liquid from the clear-washing zone 48, which contains spent and unspent wash-active substances, is intercepted in the collecting tank 23 below the drainage press 46 and is first conducted from the said collecting tank through the outflow line 55 to the pre-filter 56 and is subsequently supplied, pre-filtered by the latter by the separation of larger particles, to the filter 57 which at least for the most part removes spent wash-active substances from the treatment liquid. Thereafter, part of the prepared treatment liquid, without substantial spent wash-active substances, is conducted via the connecting line 58 and the branch point 59 of the return line 54 to the inflow funnel 29. In this case, the prepared treatment liquid originating from the pre-washing zone 47 is topped up by the same fraction which was removed from the treatment liquid from the pre-washing zone 47 during pre-filtration in the pre-filter 51 and in the filter 52. The remaining part of the treatment liquid, separated from the laundry articles by the drainage press 46, from the clear-washing zone 48 in the collecting tank 23 is conducted downstream of the filter 57 through the outflow line 60 to the start of the clear-washing zone 48.

After the drainage press 46 has separated the treatment liquid from the clear-washing zone 48 out of the laundry articles, with the exception of the residual moisture, and this treatment liquid has been removed from the collecting tank 23 and prepared by means of the pre-filter 56 and the filter 57, the rinsing of the laundry articles takes place in the drainage press 46. For this purpose, fresh water is supplied via the supply line 49 to the drainage press 46 and is pressed through the laundry articles by the drainage press, rinsing of the laundry articles taking place. The rinsing liquid pressed out of the laundry articles during rinsing is then intercepted in the collecting tank 23 and is conducted via the connecting line 61, without filtration, via the branch points 53 and 59 through the return line 54 to the inflow funnel 29 upstream of the continuous-flow washing machine 45.

There may preferably be arranged in the outflow line 55 at least one further collecting tank, in which treatment liquid from the clear-washing zone 48 is intermediately stored until it is filtered by the pre-filter 56 and the filter 57 and supplied for further use. As a result, the collecting tank 23 can be emptied of the laundry articles immediately after the separation of the treatment liquid from the clear-washing zone 48, so that the collecting tank 23 is available in a short time for the reception of rinsing liquid.

The method according to the invention is particularly suitable for the apparatus of FIG. 2, in which the continuous-flow washing machine 45 has only a pre-washing zone 47 and a clear-washing zone 48, but the rinsing of the laundry articles takes place in the drainage press 46. Here, treatment liquid from the clear-washing zone 48 and rinsing liquid from the drainage press 46 occur briefly in succession, so that prepared treatment liquid with only unspent wash-active substances is available via the rinsing liquid at the appropriate time for an operation for washing a following batch of laundry articles. The fresh-water requirement in the apparatus of FIG. 2 is thereby reduced to a minimum. In many instances, no fresh water at all needs to be supplied, because the liquid discharged by the residual moisture, together with the ready-rinsed and drained laundry articles, and the liquid separated at the pre-filters 51 and 56 and at the filters 52 and 57 with residual particles and spent wash-active substances can be used by the fresh water supplied to the drainage press 46 via the supply line 49 for rinsing the laundry articles, in order to supplement again the discharged or filtered-off treatment liquid in order to treat the subsequent batch of laundry articles in the apparatus.

In the apparatus of FIG. 2, too, the method, constituting an independent invention, of measuring during the washing process the concentration of unspent wash-active substances in the treatment fluid can be employed. In this method, basically in the same way as was described in connection with the apparatus of FIG. 1, after the separation of the spent wash-active substances from the treatment liquid, the concentration of spent wash-active substances in the treatment liquid downstream of the filters 52 and/or 57 is determined continuously (in situ) and a corresponding quantity of new wash-active substances is added to the treatment liquid in a regulated manner as a function of a desired concentration of the wash-active substances. The measurement of the concentration of unspent wash-active substances in the washing liquid takes place by means of measuring sensors or measuring probes which were referred to further above in connection with the exemplary embodiment of FIG. 1.

LIST OF DESIGNATIONS

• 10 Continuous-flow washing machine
• 11 Drainage press
• 12 Axis of rotation
• 13 drum
• 14 partition
• 15 Flow direction
• 16 chamber
• 17 Pre-washing zone
• 18 Clear-washing zone
• 19 Rinsing zone
• 20 Unloading chute
• 21 Press basket
• 22 Press plunger
• 23 Collecting tank
• 24 Outflow line
• 25 Pre-filter
• 26 filter
• 27 Branch point
• 28 Return line
• 29 Inflow funnel
• 30 Outflow line
• 31 Pre-filter
• 32 filter
• 33 Branch point
• 34 Connecting line
• 35 Return line
• 36 Branch point
• 37 Return line
• 38 overflow
• 39 Collecting tank
• 40 Intermediate line
• 41 Return line
• 42 Return line
• 45 Continuous-flow washing machine
• 46 Drainage press
• 47 Pre-washing zone
• 48 Clear-washing zone
• 49 Supply line
• 50 Outflow line
• 51 Pre-filter
• 52 filter
• 53 Branch point
• 54 Return line
• 55 Outflow line
• 56 Pre-filter
• 57 filter
• 58 Connecting line
• 59 Branch point
• 60 Outflow line
• 61 Connecting line

Claims

1. Method for the wet treatment of laundry articles, the laundry articles being at least washed in a treatment liquid containing at least one wash-active substance, and thereafter the treatment liquid being at least partially separated from the treated laundry articles, wherein spent wash-active substances are removed at least for the most part from the treatment liquid separated from the laundry articles.

2. Method according to claim 1, wherein at least one spent wash-active substance is removed at least for the most part from the treatment liquid after different treatment steps.

3. Method according to claim 1, wherein the at least one spent wash-active substance is removed at least for the most part from the treatment liquid after at least one pre-wash.

4. Method according to claim 1, wherein the at least one spent wash-active substance is removed at least for the most part from the treatment liquid a plurality of times.

5. Method according to claim 1, wherein, during a rinsing of the washed laundry articles in a drainage device, at least one spent wash-active substance is removed at least for the most part from the treatment liquid separated from the laundry articles after washing and also from the treatment liquid separated from the laundry articles before rinsing in the drainage device.

6. Method according to claim 1, wherein the at least one spent wash-active substance is separated at least for the most part from the treatment liquid by filtration.

7. Method according to claim 6, wherein pre-filtration is carried out before at least one spent wash-active substance is filtered out of the treatment liquid.

8. Method according to claim 6, wherein the filtering-out of at least a large part of at least one spent wash-active substance from the treatment liquid takes place by means of micro-filtration.

9. Method according to claim 6, wherein, during filtration, spent wash-active substances with a particle size of 0.005 μm to 10 μm are removed at least for the most part from the treatment liquid.

10. Method for the wet treatment of laundry articles, the laundry articles being at least washed in a treatment liquid containing at least one wash-active substance, and thereafter the treatment liquid being separated at least partially from the laundry articles, wherein, during treatment, the content of the at least one wash-active substance still contained in the treatment liquid is determined.

11. Method according to claim 10, wherein, after the removal of at least a large part of spent wash-active substances from the treatment liquid, the content of at least one wash-active substance still contained in the treatment liquid is determined.

12. Method according to claim 10, wherein the measured content of the at least one wash-active substance still contained in the treatment liquid is compared with a desired content of the respective wash-active substance in the treatment liquid, and, if the desired content is undershot, a corresponding quantity of at least one wash-active substance is added to the treatment liquid.

13. Apparatus for the wet treatment of laundry articles, with a washing machine having a drum (13) drivable in rotation and with a drainage device following the washing machine, wherein at least one filter (52, 57) for removing at least one spent wash-active substance in the treatment liquid is assigned to an outflow line, returned to the start of a washing zone (47, 48) for the treatment liquid from the drum (13) and to an outflow line, returned to the start of the washing zone (47, 48) from the drainage device.

14. Apparatus for the wet treatment of laundry articles with a washing machine having a drum (13) drivable in rotation and with a drainage device following the washing machine, wherein at least one filter (26, 32) for the removal of at least one spent wash-active substance from the treatment liquid is assigned to at least one outflow line, returned to the start of the washing zone (17, 18) for treatment liquid from the drum (13).

15. Apparatus according to claim 13, wherein at least one pre-filter (25, 31, 51, 56) is arranged upstream of the filter (26, 32, 52, 57) for removing at least one spent wash-active substance from the treatment liquid.

16. Apparatus according to claim 15, wherein the filter (26, 32, 52, 57) is designed as a micro-filter.

17. Apparatus according to claim 15, wherein the filter (26, 32, 52, 57) is designed as a membrane filter.

18. Apparatus according to claim 17, wherein the membrane filter is assigned at least one supporting body.

19. Apparatus according to claim 14, wherein at least one pre-filter (25, 31, 51, 56) is arranged upstream of the filter (26, 32, 52, 57) for removing at least one spent wash-active substance from the treatment liquid.

20. Apparatus according to claim 19, wherein the filter (26, 32, 52, 57) is designed as a micro-filter.

21. Apparatus according to claim 19, wherein the filter (26, 32, 52, 57) is designed as a membrane filter.

22. Apparatus according to claim 21, wherein the membrane filter is assigned at least one supporting body.