MX2012014587A

MX2012014587A - A system for treating a detergent solution in a washing or rinsing plant for containers and method for managing the operation thereof.

Info

Publication number: MX2012014587A
Application number: MX2012014587A
Authority: MX
Inventors: Berzaghi Claudio
Original assignee: Sidel Spa Con Socio Unico
Priority date: 2011-12-14
Filing date: 2012-12-13
Publication date: 2013-06-14
Also published as: BR102012031990A2; BR102012031990B1; CN103157324B; EP2604350B1; EP2604350A1; CN103157324A

Abstract

The invention relates to a system (1) for treating the detergent solution used in a washing or rinsing plant for 5 containers, the system comprising first and second treatment means of the detergent solution; first and second means (31L, 32L) for detecting and transmitting a first quantity relative to the flow of detergent solution to be treated, respectively upstream and downstream of said first 10 treatment means (3); first and second means for detecting and transmitting a second quantity relative to the flow of detergent solution to be treated, upstream and downstream of the second treatment means (4); a control unit (U) programmed to manage the activation of the treatment system 15 (1) and the starting of the operations of washing and recovery of the filtering functionality of said first and second treatment means (3, 4) as a function of the measured values of the quantities relative to the flow of solution to be treated.

Description

A SYSTEM TO TREAT A DETERGENT SOLUTION IN A WASHING OR RINSING PLANT OF CONTAINERS, AND A METHOD TO MANAGE THE OPERATION OF THE SAME FIELD OF THE INVENTION The present invention relates to a system for treating a solution and to a method for managing the operation thereof. More particularly, the invention relates to a system for treating a detergent solution in a plant for washing or rinsing containers, mainly bottles, of the type generally associated with a system for bottling a product capable of being poured, especially in the food sector.

BACKGROUND OF THE INVENTION In order to guarantee proper hygiene in the bottled product, it is known that before the filling the bottles are washed thoroughly, by means of washing machines or bottle rinsing machines. The type of machine used depends mainly on the type of bottles used (new or reusable).

The new bottles that come from glass factories, usually, are packed on wooden platforms and protected with the corresponding plastic caps 52-586-12 heat shrink that protect them from dirt. Although, in this way, the bottles are kept practically clean, in any case, they can have traces of dirt by the conditions and modes of transport and also by the duration and form of storage. Therefore, before filling, these containers are rinsed by means of dedicated washing machines, which by means of jets of filtered and sterilized water, remove and expel from the containers any remaining dust or any other impurity present therein.

In contrast, reusable bottles, in general, are dirty inside and out and therefore require an effective washing action.

For this purpose, washing machines are used in which the bottles are subjected to a series of soaking and spraying treatments with high-temperature detergent solutions alternating with repeated filling and emptying operations, followed by one or more operations of rinsing with water potable and finally drained. As they guarantee an intense washing of the containers that eliminates any trace of dirt and all the microorganisms that could be present in the same, the washing machines must also eliminate the labels or parts of these, ideally without causing defibration and kneading, which give place at considerable disadvantages. 52-586-12 The operational variables, such as the composition of the washing cycle, the operating modes, the operating temperature, the type of solution (acidic, alkaline or neutral), etc., depend on the machine used, the degree of dirt on the bottles that they will be washed, the characteristics of the water used and the pressure of the water jets, the adhesive used in the labels, the degree of concentration of the detergent solutions used, etc.

Most of the solutions used in bottle washers contain, as a main constituent, caustic soda (NaOH), usually mixed with other alkaline substances or synthetic detergents that increase the detergent power.

An important aspect to consider is related to the water that must be used to wash and rinse the bottles before they leave the washing machine. The current regulations allow the use of potable water in the final rinsing of the bottles. When this kind of resource is not available, the law allows the use of purified water obtained in specialized treatment plants that allow to meet the chemical and microbiological requirements established for the specific use.

On the other hand, it is desirable that the water has very low hardness in order to limit, as much as possible, the 52-586-12 formation of scale inside the washing plant that besides reducing the efficiency can compromise the operation of the same.

In order to avoid the formation of foam inside the washing machines, with all the undesirable consequences that result from this (spills, reduction of the pressure in the jet nozzles, reduction of the sterilization efficiency, malfunction of the pumps , etc.), defoaming agents and surfactants are added to the detergent solutions and on the other hand, the machine is provided with suitable structural defoaming devices.

The temperature and concentration of the detergent solution are, in general, inversely proportional to the duration of the treatment, which in turn is a function of the complexity of the cycle of washing the bottles. On the other hand, the temperature and concentration must be increased as well as reducing the washing cycle in order to treat very dirty containers or containers that have labels that are difficult to peel off.

Given the importance of the environmental aspects and in relation to the measures to purify water, great care must be taken in the treatment of waste water that derives from the washing of bottles and detergent products used to wash them. 52-586-12 Given the number and value of the parameters to be met by the detergent solution, both by virtue of the efficiency of washing and sanitizing the bottles and by virtue of legal requirements, it is recommended that the detergent solution not be discharged into the environment afterwards. of a single cycle of washing / washing of the containers, instead of this, prolong their use as much as possible.

In the course of the washing operations, the detergent solution is not changed but only filtered with large mesh filters with openings of 2-4 mm: over time it is physically contaminated with solid particles that come from the paper of the labels, inks, adhesives and dirt. Physical pollution caused by solid bodies prevails with respect to chemical contamination, since the concentration of the soda is controlled continuously and adjusted by an automatic control system for the concentration of the soda.

Therefore, when the content of impurities in the detergent solution used is greater than certain threshold values, operational problems may arise in the washing / rinsing plant. For example, mechanical problems can be detected in the pumps when the detergent solution extracts an excessive amount of 52-586-12 solid particles suspended.

As a consequence, periodic maintenance interventions are required to guarantee efficiency in the operation of the washing plant and the efficiency of the filtration system of the detergent solution, especially with regard to the most fragile components, such as filters and filters. means adapted to generate and direct the jets of the detergent solution inside the bottle.

Generally, in the sector the detergent solution can be changed periodically, for example, every week or every fifteen days, to reduce the costs of discharge. However, this periodicity is possible only by recycling used detergent seed after having been subjected to an appropriate treatment that maintains the properties of the detergent.

It is known that for this purpose, in the sector systems are used to treat the detergent solution that recover, at least partially, the original physicochemical properties. In general, these are mechanical systems such as decanting, filtration, etc., which are usually activated when the bottling system is not working (for example, during weekends).

Therefore, the sector is perceived as 52-586-12 need to increase the useful life of the detergent solution and reduce maintenance interventions, in particular those involving time off-duty.

In this regard, the need to provide a system for the treatment of the detergent solution used in a container washing / rinsing plant, system that allows to effectively remove solid particles suspended in the detergent solution, is perceived in the sector. , that it is possible to treat the detergent solution without interrupting the normal production cycle of the washing / scrubbing plant. On the other hand, it would be desirable to provide a system for treating the detergent solution used in a container washing / rinsing plant, which makes it possible to take advantage of the out-of-service times that are normally required to carry out the treatment, thus requiring minimums. maintenance interventions, limiting the consumption of energy, water and detergent solution during the washing / rinsing stage, etc.

SUMMARY OF INVENTION At least one of the aforementioned needs is satisfied by means of the present invention, since 52-586-12 provides a system for treating the detergent solution used in a container washing or rinsing plant as defined in claim 1.

On the other hand, it is an object of the present invention to provide a method for managing the operation of a system for treating the detergent solution used in a washing plant in a container washing and / or rinsing plant to reduce the energy consumption and the wear of moving parts. This object is achieved by means of the invention by providing a method according to claim 10.

For better understanding of the present invention, a preferred embodiment is set forth only as a non-limiting example and with reference to the accompanying drawings of Figure 1, which schematically shows a treatment system for the detergent solution used in a container washing plant according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS OR FIGURES In Figure 1, numeral (1) indicates a treatment system, as a whole, of the detergent solution for the containers used in a washing plant. 52-586-12 DETAILED DESCRIPTION OF THE INVENTION The system (1) is fluidly and operatively connected to a tank (2) that practically coincides with the detergent bath of a washing and / or rinsing machine of the aforementioned plant containers. When the machine comprises a plurality of detergent baths, the treatment system may be conveniently connected in a fluid and operative manner to a bath at a given time (i.e., with a tank (2) at a given time) by means of the respective opening / closing feeder valves provided in each bath.

On the other hand, the system (1) advantageously comprises first and second treatment means (3) and (4) configured to receive from the tank (2) an adjustable flow of detergent solution to be treated and recirculated to the same tank (2). ) an adjustable flow of treated detergent solution. The entry and exit points of the detergent solution should not be placed in areas that could alter the normal operation of the machine.

Advantageously, the tank (2) is fluidly connectable, selectively: - only to the first treatment means (3) of the detergent solution (primary treatment circuit); Y - to the primary and second treatment means of the detergent solution (3, 4) in series (circuit of 52-586-12 secondary treatment).

In more detail, the system (1) comprises a primary supply conduit (5) and a primary recirculation conduit (6) for fluidly connecting the tank (2) to the first treatment means (3) of the detergent solution. In particular, the detergent solution leaving the tank (2) can flow through the primary supply conduit (5) and the detergent solution treated by the first treatment means (3) can flow through the primary recirculation conduit (6). ) to return to the tank (2).

On the other hand, the system (1) comprises a secondary supply duct (7) for fluidly connecting the first treatment means (3) to the second treatment means (4) and a secondary recirculation duct (8) for connecting the second treatment means (4) to the tank (2). In particular, the detergent solution treated by the first treatment means (3) and directed to the second treatment means (4) can flow through the secondary supply conduit (7), while the detergent solution treated in series by the first and second treatment means (3, 4) can flow through the secondary recirculation duct (8) to return to tank (2).

The first treatment means (3) of form 52-586-12 advantageous comprises a primary filter (30), preferably of the rotating drum type, which is provided with an upper tank (31) for receiving the detergent solution to be treated and a lower tank (32) for collecting the detergent solution treated.

The filter portion of the primary filter (30) is advantageously formed by triangular elements of the wedge wire type. In general, these elements are welded to a support profile defined by the rotating drum. The distance between the triangular elements is controlled very precisely, since the width of the grooves between two adjacent triangular elements directly influences the filtration efficiency.

Advantageously, this type of filter offers continuous grooves, which due to their geometries, considerably reduce the frequency of obstruction phenomena. On the other hand, the size of the slots can be selected during the design depending on the specific characteristics of the detergent solution to be treated and the type of impurities to be filtered. Preferably, the primary filter (30) is configured to retain particles larger or equivalent to 500 μp ?.

With regard to the efficiency of the process, the 52-586-12 The surface of the cuneiform metal screen also allows the filter to be easily cleaned mechanically or by countercurrent flow.

For this purpose, the primary filter (30) is provided with a blade (33) that scrapes the rotating surface of the same, eliminating well the incrustations accumulated during the filtering process: for which the cleaning does not require energy consumption or consumption of water for countercurrent washing.

On the other hand, it should be noted that, in general, reduced head losses are associated with this type of filter.

The upper and lower tanks (31, 32) advantageously comprise respective level probes (31L and 32L).

The treatment system (1) advantageously comprises a control unit (U) operatively connected to the level probes (31L and 32L), with control means V1 of the flow of the detergent solution flowing in and out of the first treatment means and with the first treatment means (3); and configured to control the operation of the first treatment means (3) as a function of the level of the detergent solution in the upper and lower tanks (31 and 32) (upstream and downstream of the primary filter (30)). 52-586-12 In particular, the control unit (U) is configured to control the operation of the first processing means (3) according to the reasoning that will be discussed in detail later. On the other hand, the control unit is completely independent of the bottle washing and / or rinsing machine, so that it can operate independently of the state of the machine.

In particular, depending on the level that is measured in the upper tank (31), the control unit (U), selectively, opens and / or interrupts the fluid connection between the first treatment means (3) and the tank ( 2), consequently acting on the control means MV1 of the flow of detergent solution flowing in and out of the first treatment medium and on a pump Pl arranged along the primary recirculation duct 6, downstream of the filter (30) and adapted to extract the treated detergent solution from the first medium (3) and send it to the tank (2).

By monitoring the level of the lower tank (32), suitable conditions can be provided at the same time for the correct operation of the Pl pump (for example, preventing it from being idle, avoiding the presence of cavitation phenomena, etc.) It should then be considered that the amount of detergent solution that passes through the filter (30) (and 52-586-12then it passes from the upper tank (31) to the lower tank (32)) directly depends on the degree of the respective obstruction.

During use, periodically the filter (30) must be rotated about the respective axis so that the blade (33) can scrape and peel off from the surface of the drum the layer of filtrate that has accumulated over time, thus exposing a portion of the filter surface clean to the flow of the detergent solution to be treated.

Advantageously, the control unit (U) is configured to activate the rotation of the drum filter (30) (i.e., the respective operation of cleaning and recovering the filtering functionality) when the level of the solution in the upper tank (31) exceeds a predetermined threshold value Lo- On the other hand, the control unit (U) is advantageously configured to measure and store the time ti that elapses between two successive activations of the rotation of the filter (30).

When the time i exceeds a predetermined threshold value to, the control unit (U) interrupts the supply of detergent solution from the tank (2) to the first filter medium (3) since the solution can be considered clean. 52-586-12 In practice, the control unit (U) detects, by means of level measurements in the upper and lower tanks (31 and 32), the presence of a threshold obstruction condition of the filter surface portion of the primary filter (30). ) exposed to the flow of the detergent solution to be treated (hereinafter referred to as "operating portion of the primary filter"). When this condition arises, the control unit (U) activates the rotation of the primary filter (30) as described above. Since the time ti that elapses between the presence of two successive threshold obstruction conditions of the operating portion of the primary filter (30) represents an indirect index of the degree of soiling in the detergent solution to be treated, a value can be identified threshold t0 of this time interval, above which the detergent solution flowing in the primary filter (30) meets the desired quality requirements, i.e., is clean.

On the other hand, the control unit (U) is configured to intervene when, by detecting the level in the upper and lower tank (31 and 32), anomalies in the operation that can be attributed to the obstruction of the conduits are detected (5). , 6); to an obstruction or inability to rotate the primary filter (30); to the emptying of the tank (2), etc. 52-586-12 The second treatment means (4) advantageously comprises a secondary filter (40), preferably of the type having static self-cleaning rings. More preferably, the secondary filter (40) is configured to retain particles greater or equivalent to 5 μp ?.

This type of filter comprises an outer sleeve inside which the actual filtering elements are housed. These are formed by concentric metallic rings that rest on one another and are pressed by means of a pneumatic actuator. The compression force and the surface configuration of the rings ensure the correct degree of filtration required.

During normal filtration, the detergent solution passes between the sleeve and the rings, filters as it passes through the rings and flows out of the filter through the channel defined by the rings; consequently, the material that remains after the filtration is deposited on the outer surface of the rings.

To eliminate the material remaining after the filtration, a backwash operation is envisaged, during which the flow of the solution to be treated, which flows in the secondary filter (40), is interrupted. Compressed air is injected into the inner channel of the rings, the pneumatic actuator eliminates pressure between 52-586-12 the rings and the air passes between the rings and removes the material that remains after the filtration. Simultaneously, a valve placed at the bottom of the sleeve opens and allows the material remaining after filtration, the detergent solution remaining in the filter and the countercurrent air to flow outwards. After a few seconds, the valve changes state and normal flow recovers.

The treatment system (1) also comprises first and second means MI and M2 for detecting a first and second pressure valve, respectively, upstream and downstream of the second treatment means (4) (in practice, to detect variation of pressure between the upstream and downstream positions of the secondary filter (40)) and means MV2 to adjust the flow of the detergent solution treated by the first treatment means (3) and flowing in the second treatment means (4). On the other hand, a pump P2 can be provided which feeds a flow of treated water from the first treatment means (3) to the second treatment means (4) along the secondary supply conduit (7).

Advantageously, the control unit (U) is also operatively connected with the first and second pressure sensing means MI and M2, with the MV2 means for adjusting the flow of the detergent solution 52-586-12 which flows in the second treatment means (4) and with the second treatment means (4) and is configured to control the operation of the second treatment means (4) according to a logic that will be explained in detail later.

Preferably, the control unit (U) is also operatively connected to the pump P2, if present.

In particular, the control unit (U) is configured to control the flow of the detergent solution flowing in and out of the second treatment means (4), as a function of the pressure difference detected between the upstream position and downstream of the second treatment means (4).

On the other hand, the degree of obstruction of the secondary filter (40) is advantageously controlled.

In particular, as a function of the pressure difference measured between the upstream and downstream position of the secondary filter (40), the control unit (U) selectively opens and / or interrupts the fluid connection between the second means of treatment (4) and tank (2), acting in the appropriate way on MV2 media to control the flow.

In practice, when the pressure difference between the upstream and downstream position of the second treatment means (4) reaches a threshold value 52-586-12 predetermined ???, the valves are closed upstream and downstream of the secondary filter (40) and initiates a countercurrent washing operation of the secondary filter in order to recover its functionality.

On the other hand, as a function of the pressure difference measured between the upstream and downstream position of the second treatment means (4), the control unit (U) activates and inactivates a pump P2 disposed along the conduit ( 7), upstream of the secondary filter (40), to extract the treated detergent solution from the first medium 3 and send it to the secondary filter (40).

Advantageously, the control unit (U) is also configured to activate, as briefly discussed above, a backwash operation of the secondary filter (40) when the value of the pressure drop between upstream and downstream of the secondary filter (40) exceeds the threshold value? 0 already mentioned.

On the other hand, the control unit (U) is advantageously configured to measure and store the time ti 'that elapses between two successive activations of the back-flushing operation of the secondary filter (40). Under these circumstances, the control unit (U) consequently interrupts the possible feeding of treated detergent solution, from the first treatment means (3) to the second treatment means. 52-586-12 (4), that is, it interrupts the flow of the same through the conduit (7) acting in the appropriate way on the flow control means MV2.

When the time ti 'exceeds a predetermined threshold value, the control unit (U) interrupts the possible feeding of treated detergent solution from the first treatment means (3) to the second treatment means (4) (which favors the accumulation of all the solution that has already been treated in the tank (2)) since the solution can be considered clean.

In practice, the control unit (U) by means of pressure variation measurements between upstream and downstream of the second treatment means (4), detects the presence of a threshold obstruction condition of the secondary filter (40). When this condition occurs, the control unit (U) initiates a back-flushing operation of the secondary filter (40) as previously discussed. Since the time ti that elapses between the presence of two threshold obstruction conditions of the operating portion of the primary filter (30) represents an indirect index of the degree of soiling in the detergent solution to be treated, a threshold value of that time interval, above which the detergent solution flowing in the secondary filter (40) meets the desired quality requirements, ie, is 52-586-12"clean" and is reusable in new washing and / or washing cycles.

At the same time, by monitoring the level of the pressure upstream / downstream of the secondary filter (40), it is possible to guarantee adequate conditions for the correct operation of the P2 pump (preventing it from being idle, avoiding the presence of the cavitation phenomenon , etc.) From an analysis of the characteristics of the treatment system (1) of a detergent solution in a container washing or rinsing plant according to the present invention, the advantages that this allows to obtain are evident.

In particular, the treatment system (1) makes it possible to considerably increase the useful life of the detergent solution. Increases in the life of the detergent solution have been recorded, equivalent to six or seven times compared to conventional systems.

On the other hand, the treatment system (1) practically eliminates the problems related to dead times of the plant. At the same time, the life of the pumps also increases and the need for maintenance interventions is reduced, since the pumps work in better conditions. Finally, the accumulation of dirt is almost eliminated in the area of 52-586-12 rinsed In more general terms, the treatment system (1) according to the invention allows to reduce the energy consumption associated with the operations of washing and / or rinsing of containers typical of a typical filling plant of the food sector, since it allows a more use rational of the means of treatment (filtration media).

In particular, according to the method of the invention, the operation of the treatment system (1) advantageously and rapidly is interrupted when, as it indirectly detects based on the frequency that the operations of cleaning and recovery of filtering functionality in the first and second treatment means (3, 4), the control unit detects a condition of sufficient "cleaning" of the treated detergent solution, which can, therefore, be conveniently reused in a washing cycle and / or rinsing the containers.

This more rational use of the treatment system makes it possible to reduce considerably the waste of energy in the dead times of the washing and / or washing plant.

On the other hand, since the frequency of discharge to the environment of the depleted detergent solution is reduced with respect to the known systems, 52-586-12 the treatment system (1) according to the invention allows at the same time to reduce the environmental impact. Since the system (1) of the invention allows easy separation and collection of the filtrate, the latter can easily be disposed of as a generic solid waste. This represents another useful result in terms of management costs.

Finally, it is clear that modifications and variants can be made to the system described and disclosed for treating detergent solution without departing from the scope of protection of the independent claims. 52-586-12

Claims

CLAIMS:

1. A system (1) for treating a detergent solution used in a container washing or rinsing plant, the system is connected to the tank (2) of the detergent bath of a container washing or rinsing machine and is characterized by first understanding and second means (3, 4) for treating the detergent solution configured to receive from the tank (2) an adjustable flow of the detergent solution to be treated and recirculate to the same tank (2) an adjustable flow of reusable treated detergent solution in the washing or rinsing process; the tank (2) can be connected fluidly and selectively: only to the first treatment means (3) of the detergent solution; and to the first and second treatment means (3, 4) of the detergent solution in series; The system (1) also comprises: - first and second means (31L, 32L) for detecting and transmitting a first quantity relative to the flow of the detergent solution to be treated, respectively, upstream and downstream of the first treatment means (3); - first and second means for detecting and transmitting a second quantity relative to the flow of the detergent solution to be treated, respectively, 52-586-12 upstream and downstream of the second treatment means (4); - a control unit (ü) operatively connected to the first and second processing means (3, 4), to the first and second means for detecting and transmitting a first quantity of the solution flow to be treated and to the first and second means to detect and transmit a second quantity of the solution flow to be treated; and programmed to manage the activation of the treatment system (1) and the start of the operations of washing and recovering the filtering functiony of the first and second treatment means (3, 4) as a function of the measured values of the first and second one. second quantities relative to the flow of solution to be treated.

2. The treatment system according to claim 1, characterized in the first and second means for detecting and transmitting a first quantity of the solution flow to be treated comprises level probes (31L, 32L) disposed upstream and downstream of the first medium of treatment (3), the control unit (U) is programmed to start the operation of washing and recovering the filtering functiony of the first treatment means (3) when the level of the solution to be treated detected upstream of the first half of 52-586-12 treatment (3) exceeds predetermined threshold value L0.

3. The treatment system according to claim 2, characterized in that the control unit (U) is programmed to interrupt the feeding of detergent solution to be treated coming from the tank (2) to the first treatment means (3) when the time ti between two successive starts of the washing and recovery operation of the filtering functiony of the first treatment means (3) exceeds a predetermined threshold value t0.

4. The treatment system according to any of claims 1 to 3, characterized in that the first and second means for detecting and transmitting a second quantity of the solution flow to be treated comprise pressure sensing means (MI, M2) disposed upstream and waters downstream of the second treatment means (4), the control unit (U) is programmed to start a washing and recovery operation of the filtering functiony of the second treatment means (4) when the pressure difference between upstream and downstream of the second treatment means (4) exceeds a predetermined threshold value ???

5. The treatment system according to claim 4, characterized in that the control unit (U) is programmed to interrupt the feeding of 52-586-12 detergent solution to be treated from the first treatment means (3) to the second treatment means (4) when the time ti between two successive starts of the washing operation and recovery of the filtering functiony of the first treatment means (4) exceeds a predetermined threshold value t0 '.

6. The treatment system according to any of claims 1 to 5, characterized in that the first treatment means (3) comprises a primary rotary drum filter (3) of the type that includes elements of a wedge-shaped metal screen and configured to retain larger or equal particles at 500 μp?

7. The treatment system according to any of claims 1 to 6, characterized in that the second treatment means (4) comprises a secondary ring filter (40) configured to retain particles greater than or equal to 5 μ ??.

8. A plant for bottling a product capable of being poured, comprising a treatment system (1) of the detergent solution for washing or rinsing containers to be filled, according to any of claims 1 to 7.

9. A control unit (U) for a treatment system (1) of the detergent solution used in a container washing or rinsing plant according to 52-586-12 any of the preceding claims.

10. A method for managing the operation of a system (1) comprising first (3) and second (4) treatment means for the detergent solution used in a container washing and rinsing plant, which consists of the following steps: a) detecting a first quantity relative to the flow of detergent solution to be treated upstream and downstream of the first treatment means (3); b) detecting a second quantity relative to the flow of detergent solution to be treated upstream and downstream of the second treatment means (4); c) initiating the respective operations of washing and recovering the filtering functionality of the first and second treatment means (3, 4) as a function of the first and second measured quantity relative to the flow of solution to be treated; and d) interrupting the feeding to the first treatment means (3) of detergent solution to be treated when the time ti between two successive starts of the operations of washing and recovering the filtering functionality of the first treatment means (3) exceeds a predetermined threshold value t0-

11. The method according to claim 10, characterized in that it comprises the following steps: 52-586-12 e) interrupting the feeding of the detergent solution to be treated, from the first treatment means (3) to the second treatment means (4) when the time ti 'between two successive starts of the operations of washing and recovery of the filtering functionality of the second medium of treatment (3) exceeds a predetermined threshold value to '. 52-586-12