WO2019212339A1

WO2019212339A1 - Method and machine for cleaning metal mesh type protective clothing

Info

Publication number: WO2019212339A1
Application number: PCT/NL2019/050251
Authority: WO
Inventors: Willem Frans NEELS; Marinus Jan VAN DEN BRINK
Original assignee: Unikon B.V.
Priority date: 2018-05-04
Filing date: 2019-04-30
Publication date: 2019-11-07
Also published as: NL2020880B1

Abstract

Method and machine for cleaning metal mesh type protective clothing soiled with meat remains. The metal mesh type clothing soiled with meat remains can be very effectively cleaned in a drum (5) type washing machine (1) at elevated temperatures using a washing composition in large batches.

Description

Method and machine for cleaning metal mesh type protective clothing

The present invention relates to a method and a machine for cleaning metal mesh type protective clothing soiled with meat remains .

Introduction

Meat packing and processing industries involve manual or semi-manual cutting operations. Safety regulations re quire that the person operating the cutting equipment or device wears protective clothing, such as gloves and/or an apron made of metal mesh material. Such clothing is commonly referred to as chainmail protective clothing.

Because the clothing is in constant contact with food, it has to be cleaned on a regular basis. This has to be done thoroughly in order to minimize risks of food contamination by for instance harmful microorganisms.

The metal mesh structure causes cleaning difficulties, because during operation meat sticks in the crevices and spaces of the metal mesh structure. Meat and fish particles, in particular sinews tend to be sticky and have a strong tendency to get stuck in the mesh structure of the protective clothing .

Various methods for cleaning metal mesh type protective clothing have been proposed.

For instance, FR2647038 (Al) describes a method for cleaning chainmail gloves, wherein a) a glove is placed on an artificial hand mounted for this purpose firmly on a frame which holds it in a fixed position; b) the glove is impregnated with a detergent solution which partially dis solves waste accumulated between the links of said glove; c) the glove is washed and then rinsed by spraying hot water at high pressure onto it to expel the dissolved impurities and undissolved impurities from said glove; d) the glove is impregnated with a bactericidal solution; and e) the cleaned glove is removed from the artificial hand.

FR2711324 (Al) also describes the use of placing a chainmail glove on an artificial hand. In this document an apparatus is described for cleaning a chainmail glove mounted on such an artificial hand by means of jets of water sprayed through a number of nozzles and revolving injectors, the water being under pressure.

EP2425901 and NL9201579 describe devices for cleaning chainmail gloves, wherein a chainmail glove to be cleaned is slipped over a nozzle. The glove is then cleaned by means of high pressure water from said nozzle.

The above methods and devices do not allow cleaning metal mesh type protective clothing in large batches.

This is in particularly disadvantageous in large slaughterhouses. For instance, when many workers of a slaughterhouse take a break at a time, many gloves will have to be cleaned simultaneously. If this cleaning would take a long time, the slaughterhouse would need at least double the amount of protective clothing to prevent lag time and de lays .

Moreover, due to the fact that each piece of protective clothing needs to be handled separately with the cleaning methods known in the art, it is common practice that dedi cated personnel is hired for cleaning of the protective clothing .

Furthermore, the methods in the art make use of high pressure cleaning techniques which use a lot of water and energy. High pressure cleaning techniques also require that protective clothing can be directly reached by a spray noz zle to ensure effective cleaning, thus limiting the amount of pieces of protective clothing that can be cleaned simul taneously .

The present invention aims to overcome these ad vantages . Summary of the invention

The present invention is based on the finding that metal mesh type clothing soiled with meat remains can be very effectively cleaned in a drum type washing machine at elevated temperatures using a washing composition in large batches .

In a first aspect the invention relates to a method for batch-wise cleaning of metal mesh type protective clothing, comprising washing of multiple pieces of metal mesh type protective clothing soiled with meat remains simultaneously in a rotatable drum at elevated temperature; wherein washing comprises: supplying a washing liquid into said drum to fill at least a part of said drum containing said multiple pieces of metal mesh type protective clothing with said washing liquid; and rotating said drum to effect tumbling of said multiple pieces of metal mesh type protective clothing in and out of the washing liquid.

In a second aspect the invention relates to a drum type washing machine for batch-wise cleaning of metal mesh type protective clothing soiled with meat remains, comprising a first chamber adapted to contain washing liquid, a drum contained in said first chamber and rotatable with respect to a horizontal axis of the washing machine by receiving a rotational force from a driving motor, the drum having a plurality of pores allowing liquid to pass through the drum, the drum having a receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains; wherein said first chamber com prises a washing liquid inlet and a washing liquid outlet; a filter unit located downstream of said washing liquid outlet adapted to filter meat remains out of washing liquid; and recirculation means configured to recirculate filtered washing liquid back into the first chamber via the washing liquid inlet .

It is preferred that the method of the invention is carried out with the drum type washing machine according to the invention. Short description of the drawings

Fig. 1 shows a perspective view of a schematic repre sentation of an exemplary embodiment of the drum type wash ing machine according to the invention.

Fig. 2 shows a front view of the drum type washing machine of Fig. 1.

Fig. 3 shows a side view of the right side of the drum type washing machine of Fig. 1.

Fig. 4 shows a rear view of the of the drum type washing machine of Fig. 1.

Fig. 5 shows a top view of the washing machine of Fig.

1.

Fig.6 shows how a filter cassette can be used between the first and second chamber. Fig. 6A shows a perspective view of a schematic representation of an exemplary embodi ment of said cassette. Fig 6B shows a side view and Fig. 6C shows a top view. Fig. 6D shows a drum type washing machine according to the invention comprising said filter cassette.

Detailed description of the invention

The present invention allows cleaning of steel mesh type protective clothing in large batches in a few minutes time. For instance, in accordance with the invention it becomes possible to clean at least 200 chainmail gloves simultaneously in a few minutes time. This way the full stock of protective clothing can be cleaned during lunch or coffee breaks and taken again when work is resumed. The present invention removes the necessity to have a large overstock of protective clothing. The use of a rotating drum to effect tumbling of the protective clothing in and out of the washing liquid inside drum effects full contact of the washing liquid with any piece of protective clothing and the inventor has observed very effective cleaning in a few minutes .

The invention is directed to the cleaning of steel mesh type protective clothing. Steel mesh type clothing may also be referred to as chainmail protective clothing, and these terms are used interchangeably in this application. Said steel mesh type protective clothing may suitably be gloves or aprons. Gloves or aprons or any combination thereof can be cleaned in accordance with the invention.

The present invention is in particular directed to the cleaning of steel mesh type protective clothing soiled with meat remains. The term meat remains is meant to encompass fish meat remains as well as meat remains from any other animal, such as pig, cow, horse, chicken, sheep, etc. The invention is in particular suitable to remove persistent remains which have a tendency of getting stuck between the rings of chainmail structures, such as tendons and sinews, from the crevices and openings of the chainmail.

The combination of washing at elevated temperatures and washing liquid in the method of the invention results in degradation and remains sticking in the protective clothing. To this effect, it is preferred that washing takes place at a temperature above 50 °C, preferably above 60 °C, more preferably above 65 °C. A further beneficial effect of the use of such temperatures is that exposure to these temper atures also leads to disinfection of the protective cloth ing .

In a preferred embodiment the washing liquid is an alkaline washing composition with a pH between 12 and 14. These compositions are preferably based on sodium hydroxide or potassium hydroxide or a combination thereof. Additives may be added thereto, for instance complexing agents, foam inhibitors and dispersing agents. These compositions in com bination with an elevated temperature lead to complete dis integration of soft tissue sticking into the protective clothing in a very short time. As a result meat remains are easily removed from the crevices and spaces of the metal mesh structure. A particularly suitable composition which the inventors have observed to be very effective in this respect comprises sodium hydroxide, potassium hydroxide, ethylene diamine tetra acetate, alanine, n, n, bis (carboxyme- thyl ) -trisodium salt and alkylethoxypropoxylates . These washing liquids are preferably used for washing at a tem perature above 65 °C, and preferably between 65 °C and 70 °C. Preferred ratios between these components are 20-25 parts of sodium hydroxide: 2-2,5 parts potassium hydroxide: 1-2,5 parts of ethylene diamine tetra acetate: 1-2,5 parts of alanine, n, n, bis (carboxymethyl) -trisodium salt: 0,5-1 parts of alkylethoxypropoxylate, dissolved in water. Suit able concentrations can be determined based on the persis tence of the meat remains which may differ between the par ticular kind of meat processed.

In view of the preferred washing liquid as described above it is preferred that at least the drum is made of stainless steel. Also the chamber in which the drum is mounted is preferred to have at least a stainless steel surface, because it contains washing liquid. This way the drum and the chamber containing the drum are resistant to wards the corrosive properties of the alkaline washing liq uid. Furthermore, stainless steel is also wear-resistant, which is particularly advantageous because the chainmail protective clothing to be washed would otherwise lead to a limited life span of the rotatable drum.

The drum may suitably have a cylindrical structure, although other structures may also be possible.

It is preferred that the rotating drum during washing is filled only partially with said washing liquid. In a suitable embodiment a drum having a plurality of pores is positioned in a chamber which can be partially filled with washing liquid. The pores in the drum allow liquid to pass through in and out of the drum while rotating. Rotation of the drum results in tumbling of the protective clothing in and out of the washing liquid, resulting in a rinsing action which contributes to the effectivity of the wash treatment. In order to enhance tumbling of protective clothing to max imize proper rinsing with the washing liquid through the steel mesh of the clothing, the drum preferably contains a plurality of lifting means arranged inside the drum to fa cilitate tumbling. For this purpose, the drum is preferably equipped with a plurality of lifting ribs arranged inside the drum.

The washing liquid can be discharged from the drum simultaneously with supplying the washing liquid into the drum (continuous washing cycle) or it can be supplied first and discharged subsequently after a predetermined period of rotating the drum (discontinuous washing cycle) .

To maximize the effect of rinsing the washing liquid through the steel mesh of the clothing it is also preferred that the method of the invention comprises multiple cycles of washing. In a suitable exemplary embodiment 3 to 6 cycles of washing protective clothing in washing liquid for 1 mi nute at 65 C° and discharging the washing liquid result in complete cleaning and disinfection of the protective cloth- ing.

It is preferred to recycle washing liquid after dis charging said washing liquid from said multiple pieces of metal mesh type protective clothing, for further use of washing the same batch of metal mesh type protective cloth- ing or for use in washing a further batch of multiple pieces of metal mesh type protective clothing. It is for this reason that the drum type washing machine according to the inven tion is equipped with a filter unit located downstream of the washing liquid outlet of the chamber containing the rotatable drum. This filter unit is adapted to filter meat remains out of washing liquid. After filtration, recircula tion means transport the washing liquid back to the chamber containing the drum. Such recirculation means may for in stance be realized by means of a suitable tubing configura- tion and a pump. In one embodiment the drum type washing machine according to the invention comprises a second cham ber positioned downstream of said filter unit, which second chamber is configured to receive filtered washing liquid. In this embodiment said recirculation means is configured to recirculate filtered washing liquid back to the first chamber from said second chamber. In another embodiment a second chamber is positioned below the first chamber and in fluid connection therewith by means of a fluid connection. In this embodiment said fluid connection is configured such that used washing liquid can stream from the first chamber to the second chamber by gravitational force. Such fluid connection can instance be a pipe, optionally with a sieve of filter therein. In this embodiment the filter may be provided upstream or downstream of the second chamber.

In a preferred embodiment a filter is placed between the first and the second chamber in the form of a filter cassette. The filter cassette is provided with a grid at least on its bottom portion, which allows flow of filtered washing liquid through it. This can for instance be a stain less steel grid. Over said grid a removable filter material can be arranged for filtering out meat remains from said washing liquid. In a preferred arrangement this is a nylon bag with 200 ym pores. Such a bag allows to filter out meat remains very efficiently. The filter material is preferably designed to be placed fittingly into the filter cassette so that folds and crevices are minimalised and meat remains cannot accumulate in the filter material at places which are hard to access such as these folds and crevices. The filter cassette preferably has a bottom portion which is inclined in order to define in the bottom grid a deepening, such as a bottom groove, in which meat remains can accumulate by gravity. For instance, multiple bottom portions can be in clined to form a deepening at their contact point (s) or a single inclined bottom portion can form said deepening to gether with one or more side walls, which on their turn may also be inclined. The inventors have observed that this way fatty material and meat remains accumulate in the bottom area of the filter in abovementioned deepening, and do not clog the higher portions of the filter, thus allowing un hindered flow of washing liquid through the filter. This is in particular advantageous of continuously washing is intended as discussed in the embodiment below. Meat remains in the bottom area can be manually removed at any time, even during the washing process, because the filter cassette may be removed from the outside, for instance with a handle. It is therefore preferred that said filter unit comprises a filter cassette positioned between said first and second chamber, wherein said filter cassette is provided with a grid at least on its bottom portion, which grid is configured for allowing flow of filtered washing liquid through it, and a filter bag arranged on the grid of said filter cassette and configured for filtering out meat remains from said washing liquid; wherein in said filter cassette at least part of the bottom portion is inclined in order to define a deepening, such as a bottom groove, in which meat remains can accumulate in the respective filter material covering it .

In one embodiment the method of the invention comprises a) supplying washing liquid into said drum during ro tation of the drum while discharging washing liquid from said rotating drum;

b) directing the discharged washing liquid over a fil ter to filter out meat remains from said discharged washing liquid,

c) redirecting of the filtered washing liquid back into said drum,

wherein steps a) to c) take place continuously during a predetermined period of time. In this embodiment washing liquid is continuously pumped in and out the drum while rotating, so that a constant level of washing liquid is maintained in the drum. The discharged washing liquid is directed through a filter and subsequently directed into the drum again. The washing liquid thus continuously cycles in and out the drum with a filtration step between discharging the washing liquid from the drum and supplying it back again. The inventors have observed that when washing liquid is continuously circulated a number of advantageous effects are achieved. The inventors have namely observed that heat loss occurs, because the recycling allows the washing machine to warm up. The inventors have also observed that foaming of the washing liquid was markedly reduced compared to washing protocols where washing liquid was not continuously circu lated. In addition, the inventors have observed that by continuous circulation meat remains are removed more effec tively. This way meat remains can be removed in shorter time and less concentrated washing liquids can be used.

In a further embodiment the method of the invention comprises recycling of washing liquid and multiple cycles of washing, wherein at least a first cycle comprises:

a) supplying washing liquid into said drum during ro tation of the drum while discharging washing liquid from said rotating drum;

c) redirecting of the filtered washing liquid back into said drum, wherein steps a) to c) take place continuously during said first cycle. The advantages of continuous cir culation have been discussed above. It is preferred that in case multiple washing cycles are applied, that only the first cycle takes place under continuous circulation, be cause the inventors have observed that one washing cycle of continuous circulation already removes most of the meat re mains, so that next steps may require less intensive proce dures. This saves energy. The subsequent cycles may then be performed discont inuously, i.e. by supplying a washing liq uid into said drum to fill at least a part of said drum containing said multiple pieces of metal mesh type protec tive clouhing with said washing liquid; rotating said drum to effect tumbling of said multiple pieces of metal mesh type protective clothing in and out of the washing liquid; and discharging the washing liquid after supplying the same washing liquid and after a predetermined period of rotation. Of course, if energy reduction is less important, all wash ing cycles may be performed under continuous circulation of washing liquid. This results in very short times required for cleaning steel mesh type protective clothing. In between wash cycles or during recycling washing liq uid chemicals may be replenished. It is therefore preferred that the drum type washing machine according to to the in vention comprises a means for replenishing washing liquid chemicals. Such means may comprise a reservoir for washing liquid chemicals and a dosage pump for dosing the chemicals into the washing liquid, for instance into the second cham ber .

It is preferred that washing is followed by rinsing said multiple pieces of metal mesh type protective clothing with water to remove residual washing liquid, because re sidual washing chemicals may be harmful for the user. It is highly preferred that also the outside of the drum and the chamber in which the drum is mounted are rinsed with water, because also there remaining washing liquid and meat remains may be present, which may otherwise enter the drum. There fore, the machine according to the invention preferably com prises means for charging and discharging water into and from said first chamber. Such means may suitably comprise pipes and a pump for pumping the water into the drum. A nozzle for spraying water may be provided inside the drum for this purpose, for instance protruding from the horizon tal axis that drives rotation of the drum. Also inside the chamber but on the outside of the drum one or more nozzles may be provided for spraying water in the parts of the chamber surrounding the drum. For disinfection purposes, it is preferred that rinsing with water preferably takes place at higher temperatures than the temperatures used for wash ing with washing liquid. It is preferred that rinsing with water takes place with water having a temperature of 70 °C or more, such as 75 °C or more, or 85 °C or more.

The method according to the invention may also comprise a step of drying said protective clothing after washing and rinsing, for instance by centrifuging the drum or blowing the protective clothing with hot air. The inventors have observed that especially the latter results in complete re moval of microorganisms. The machine according to the invention may be a top load type or a front load type machine. It is preferred that the machine is a front load type machine because this fa cilitates placing the pieces of soiled chainmail protective clothing in the machine and taking them out. It is therefore preferred that the machine has a front section with said receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains. In case the machine is a top load type machine it has a top section with said receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains.

In a further preferred embodiment the machine according to the invention has a front and back section, one having said receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains, the other having an opening for taking out cleaned multiple pieces of metal mesh type protective cloth ing. In this respect the method also may comprise placing a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains in the receiving opening, followed by washing, and after washing, taking out cleaned multiple pieces of metal mesh type protective clothing from other opening. This embodiment is particularly suitable in case of short breaks during the working day at a slaughter house. The machine may be positioned suitably at a place with the receiving opening directed to the route where work ers pass on the way to a resting place ("the dirt side") and with the other opening directed to the route where workers pass after having their break in the resting place ("the clean side") . The workers may then conveniently drop their gloves and/or aprons in the receiving opening on the way to their break, and take them back from the other opening on the route back to the work place. Detailed description of the drawings

The invention will now be further elucidated in the attached drawings. The following explanation is meant to illustrate and explain the invention and not to limit the claims .

Figs. 1 to 5 show an exemplary embodiment of the drum type washing machine 1 for batch-wise cleaning of metal mesh type protective clothing soiled with meat remains according to the invention. Fig. 1 shows a perspective view. Fig. 2 shows a front view of the same machine. Fig. 3 shows a side view of the right side of of the same machine. Fig. 4 shows a rear view of the same machine. Figure 5 shows a top view of the same machine.

In the machine shown in Figs. 1-5 the washing machine is a front load washing machine which comprises a first chamber 2 in housing 3. For purposes of explanation the top side of the housing is omitted from the drawing so that the position of the drum in the first chamber can be visualized. Operation of the machine is controlled via control unit 4. First chamber 2 has a stainless steel surface to adapt it to contain highly alkaline washing liquid. Rotatable drum 5 is contained in first chamber 2 and rotatable with respect to a horizontal axis 6 of the washing machine by receiving a rotational force from a driving motor 7. Drum 5 has a cylindrical structure with a plurality of pores 8 allowing liquid to pass through it. Because machine 1 is of a front load type it has a receiving opening 9 for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains. Receiving opening 9 can be closed by means of door 10 which has a safety lock 11, which for safety reasons is adapted such that the door can only be opened by means when the washing process is completed. The door has hinges 12 to enable opening and closing. For pur poses of explanation the part of the door normally covering receiving opening 9 when the machine is in operation is omitted from Figs. 1 and 2 so that the position of the drum in the first chamber and the inside of the drum can be visualized.

In order to supply a washing liquid inside drum 5 to fill a part of it with said washing liquid when the machine is in action washing liquid is pumped from second chamber 13, which is a tank for containing washing liquid, by means of pump 14 via pipes 15 and 16 and chamber inlet 17 into first chamber 2. Washing liquid can be removed from first chamber 2 via chamber outlet 18, which is placed on the bottom of first chamber 2, via pipe 19 by means of pump 20. Pump 20 further pumps the used washing liquid via pipe 21 to filter unit 22. Filter unit 22 is adapted to filter meat remains out of washing liquid by the provision of a fabric filter bag. Filter unit 22 can be opened and closed by means of closing means 23. After passing the filter, the filtered washing liquid is directed back to tank 13 via pipe 24, from which it can be recycled back to first chamber 2.

In situations where filtering is not necessary, for instance when cleaning the machine or when it is desired that washing liquid is not recycled, a side pipe 25 is provided in pipe 19 so that filter unit 22 can be bypassed and exit the machine via outlet 26 in pipe 28. Pipe 28 is also coupled to the tank via tank outlet 29 to enable the tank to be emptied using valve 27.

Heat elements 30 are provided in first chamber 2 and tank 13 to elevate the temperature of the washing liquid. The bars of the heat elements which are not shown in the present drawings extend into first chamber 2 and tank 13. In order to ensure adequate levels of washing liquid in first chamber 2, a floater based water level meter 31 is provided in first chamber 2.

Water for rinsing remaining washing liquid from the washed gloves may be sprayed into drum 5 by nozzle 32. Nozzle 32 is connected via tube 33 to an inlet 34. To control flow through tube 32 a valve 35 is provided. Inlet 34 may be connected to a water source. Inlet 34 is provided with a flow meter 36. Water may also be sprayed into chamber 2 via chamber inlet 37 and pipe 38 which is also connected with inlet 34. Flow through pipe 38 is controlled via valve 39.

Inlet 34 may also be used for supply or replenishment of washing liquid or water into tank 13 via tube 40 which can be controlled by means of valve 41. Liquid enters tank 13 from tube 40 via tank inlet 42.

Washing chemicals or concentrated washing liquid may be dosed into the tank via dosage pump 43. If dosage pump 43 is used, tube 40 may be used for supply of water into tank 13 via tank inlet 42 from a water source connected to tube inlet 34 in order to dilute the washing chemicals or concentrated washing liquid to concentrations suitable for washing chainmail protective clothing.

Figure 6D shows another exemplary embodiment of the drum type washing machine 1 for batch-wise cleaning of metal mesh type protective clothing soiled with meat remains ac cording no the invention. In this embodiment the drum type washing machine according to the invention comprises a sec ond chamber 13 positioned downstream of a filter unit 221, which second chamber is configured to receive filtered wash ing liquid. The filtered washing liquid can be recycled back to the first chamber from said second chamber. In this embodiment the second chamber 13 is positioned below the first chamber 2 and in fluid connection therewith by means of filter cassette 221, such that used washing liquid can stream from the first chamber 2 to the second chamber 13 by gravitational force. The embodiment depicted in Fig. 6 com prises a filter cassette 221 positioned between said first chamber 2 and tank 13. A filter bag can be arranged in said filter cassette as filter material, for instance a nylon bag with 200 pm pore size (not shown) . The filter cassette is provided with a grid at least on its bottom portion, which grid is configured for allowing flow of filtered washing liquid through it . As shown in Figs 6A-C said filter cassette has a bottom portion which is inclined 224 in order to define in the grid a bottom groove 226 in which meat remains can accumulate in the respective filter material covering it . In the present embodiment said filter cassette has an in clined bottom portion 224 which forms said bottom groove 226 together with an inclined side wall 223. The height of second side wall 225 can be designed such that bottom portion 224 is inclined with a desired slope. Meat remains in the filter material in deepening 226 can be manually removed at any time, even during the washing process, because the filter cassette may be removed from the outside, with handle 222 and using rail 227.

Claims

1. Method for batch-wise cleaning of metal mesh type protective clothing, comprising washing of multiple pieces of metal mesh type protective clothing soiled with meat remains simultaneously in a rotatable drum at elevated tem perature; wherein washing comprises:

supplying a washing liquid into said drum to fill at least a part of said drum containing said multiple pieces of metal mesh type protective clothing with said washing liquid; and

rotating said drum to effect tumbling of said multiple pieces of metal mesh type protective clothing in and out of the washing liquid.

2. Method according to claim 1, comprising

c) redirecting of the filtered washing liquid back into said drum,

wherein steps a) to c) take place continuously during a predetermined period of time.

3. Method according to any of the previous claims, comprising multiple cycles of washing.

4. Method according to any of the previous claims, comprising multiple cycles of washing, wherein at least a first cycle comprises:

a) supplying washing liquid into said drum during ro tation of the drum while discharging washing liquid from said rotating drum; b) directing the discharged washing liquid over a fil ter to filter out meat remains from said discharged washing liquid,

c) redirecting of the filtered washing liquid back into said drum,

wherein steps a) to c) take place continuously during said first cycle.

5. Method according to any of the previous claims, comprising a step of recycling washing liquid after dis charging said washing liquid from said multiple pieces of metal mesh type protective clothing for use in washing a further batch of multiple pieces of metal mesh type protec tive clothing.

6. Method according to any of the previous claims, wherein washing is followed by rinsing said multiple pieces of metal mesh type protective clothing with water to remove residual washing liquid.

7. Method according to any of the previous claims, further comprising a step of drying said protective clothing after washing and rinsing.

8. Method according to any of the previous claims, wherein said protective clothing are gloves, or aprons or a combination thereof.

9. Method according to any of the previous claims, wherein washing takes place at a temperature above 50 °C, preferably above 60 °C, more preferably above 65 °C.

10. Method according to any of the previous claims, wherein said washing liquid is an alkaline washing composi tion with a pH between 12 and 14.

11. Method according to claim 10, wherein said washing liquid is based on sodium hydroxide or potassium hydroxide or a combination thereof.

12. Method according to claim 11, wherein said alkaline washing composition comprises sodium hydroxide, potassium hydroxide, ethylene diamine tetra acetate, alanine, n, n, bis (carboxymethyl) -trisodium salt and alkylethoxypro- poxylates and wherein washing is preferably performed be tween 65 and 70 °C.

13. Method according to any of the previous claims, wherein said drum is of stainless steel.

14. Method according to any of the previous claims, wherein said drum contains a plurality of lifting means arranged inside the drum to facilitate tumbling.

15. Method according to claim 14, wherein said drum is equipped with a plurality of lifting ribs arranged inside the drum.

16. A drum type washing machine for batch-wise cleaning of metal mesh type protective clothing soiled with meat remains, comprising

a first chamber adapted to contain washing liquid, a drum contained in said first chamber and rotatable with respect to a horizontal axis of the washing machine by receiving a rotational force from a driving motor, the drum having a plurality of pores allowing liquid to pass through the drum, the drum having a receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains;

wherein said first chamber comprises a washing liquid inlet and a washing liquid outlet; a filter unit located downstream of said washing liquid outlet adapted to filter meat remains out of washing liquid; and

recirculation means configured to recirculate filtered washing liquid back into the first chamber via the washing liquid inlet .

17. The drum type washing machine according to claim 16, comprising a second chamber positioned downstream of said filter unit, which second chamber is configured to receive filtered washing liquid, and wherein said recircu lation means are configured to recirculate filtered washing liquid back to the first chamber from said second chamber.

18. The drum type washing machine according to claim 16 or 17, comprising a second chamber positioned downstream of said filter unit, wherein the second chamber is posi tioned below the first chamber and in fluid connection therewith by means of a fluid connection, wherein said fluid connection is configured such that used washing liquid can stream from the first chamber to the second chamber by grav itational force.

19. The drum type washing machine according to claim 18, wherein said filter unit comprises

a filter cassette positioned between said first and second chamber, wherein said filter cassette is provided with a grid at least on its bottom portion, which grid is configured for allowing flow of filtered washing liquid through it, and

a filter material arranged on the grid of said filter cassette;

wherein at least part of said bottom portion is in clined in order to define a deepening in which meat remains can accumulate in the respective filter material covering it .

20. The drum type washing machine according to claim 19, wherein said deepening is a bottom groove.

21. The drum type washing machine according to any of the claims 16 to 20, having a front section with said re ceiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat re mains .

22. The drum type washing machine according to claim 21, having a front and back section, one having said re ceiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat re mains, the other having an opening for taking out cleaned multiple pieces of metal mesh type protective clothing.

23. The drum type washing machine according to any of the claims 16 to 20, having a top section with said receiving opening for receiving a batch of multiple pieces of metal mesh type protective clothing soiled with meat remains.

24. The drum type washing machine according to any of the claims 16 to 23, further comprising a means for replen ishing washing liquid chemicals.

25. The drum type washing machine according to any of the claims 16 to 24, further comprising means for charging and discharging water into and from said first chamber.

26. Method according to any of the claims 1 to 15, wherein washing of said multiple pieces of metal mesh type protective clothing is carried out with the drum type wash ing machine according to any of the claims 15 to 25.

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