WO2013151496A1

WO2013151496A1 - System for food waste treatment

Info

Publication number: WO2013151496A1
Application number: PCT/SE2013/050374
Authority: WO
Inventors: Lars Holmqvist
Original assignee: DISPERATOR AB
Current assignee: DISPERATOR AB
Priority date: 2012-04-05
Filing date: 2013-04-05
Publication date: 2013-10-10
Anticipated expiration: 2014-10-05
Also published as: SE1250350A1; EP2834019A1; EP2834019A4

Description

Arrangement for the treatment of food waste

The present invention relates to an arrangement for the treatment of food waste, and in particular for the treatment of food waste in industrial kitchens (both on land and at sea) , restaurant kitchens, the foodstuffs industry, the retail grocery industry, and similar.

There is, in particular in industrial kitchens, a problem of dealing with the prepared food that has not been consumed, and that, according to currently valid regulations, must be discarded as waste. It is an equivalent problem for not only industrial kitchens but also restaurants to deal with the food that is left on plates, and that thus is discarded as food waste.

Previously, such food waste has most often been collected in large containers, often mounted on wheels, and which subsequently must be stored in cooled waste-storage rooms, in order for it to be possible later to be dealt with and transported to a location for placing into a landfill or to be digested.

It is also known to mill down all such food waste for temporary collection in a storage container, to which is connected a vacuum suction arrangement in order to remove the food waste by suction.

It is, of course, theoretically possible also to mill down the waste and mix it with water and release it into the normal waste water system, but this is something that many municipalities today want to avoid, in order not to place an unnecessary load on the waste water system and waste water treatment plants . A local collection of food waste at the kitchen for subsequent digestion of the food waste, without mixing in other waste that ends up in the waste water system, has, in addition, the advantage that such digestion residual is generally free from heavy metals and other unwanted contaminants .

It is, therefore, one purpose of the present invention to achieve an efficient arrangement for the local treatment of such food waste at industrial kitchens and similar, such that the food waste can be simply collected for subsequent transport to further processing, and, in particular, the avoidance of an expensive management of the food waste in cooled rooms .

The purpose of the invention stated above is achieved with an arrangement according to the invention, which comprises a receiver for the food waste, a mill connected to the receiver in order to mill the food waste down to the intended maximum waste size, an eccentric screw pump arranged after the mill in order to pump the milled food waste via a transport line to a food waste tank, in which the food waste can be stored while waiting for it to be emptied and removed. The food waste is stored in the tank in a nearly anaerobic environment in which its rate of break down is severely retarded while waiting for it to be removed. Such a removal can be easily carried out with the aid of, for example, a slurry tanker. Through the food waste being stored in a closed tank while waiting for its removal, the food waste will be stored in an essentially oxygen-free environment. It is preferable that the receiver, mill and eccentric screw pump mentioned above are arranged in one common unit, for example a cabinet that contains at least these components.

In the same way, it is preferably arranged such that at least one of the mill and the pump comprises a connection to a water supply line such that water can be added as necessary in order to be able to pump the food waste via the transport line to the food waste tank.

The pump for the pumping operation of the food waste to a food waste tank is an eccentric screw pump, which has the ability to pump material with varying viscosity along comparatively long distances of pipe, and also with a considerable climb.

It is appropriate that there is arranged in the food waste tank some form of level monitor, for example floats that activate electrical switches, that warn not only when emptying of the tank needs to be ordered but also when the tank is full, and in this case it is appropriate that such level monitors switch off both the mill and the pump.

Through the food waste being, in accordance with the invention, supplied with as little water as possible, efficient treatment of the food waste is achieved, with reduced treatment costs as a consequence of this.

It is a significant difference that the food waste is to be pumped to a closed tank without drainage of water. This gives also a reduction in the consumption of water and it eliminates the need for water purification. Technology that is sparing in its use of water is also something that is in ever-higher demand today, and in many countries it is a requirement that new equipment is to be sparing in its use of water. This is further accentuated in that fresh water must be used in kitchens, not only on land but also at sea, and in the foodstuffs industry, due to the currently valid hygiene requirements.

The invention will now be described in more detail in the form of a non-limiting embodiment, illustrated with the aid of the attached drawings, where Figure 1 shows a schematic side view of a part of the arrangement according to the invention, with a partly cut away front panel in order to illustrate the contents of a cabinet that comprises several of the components of the arrangement, and Figure 2 shows a schematic view of how the unit with the receiver, mill and pump may be connected to a tank.

Thus, Figure 1 shows a frontal view of a cabinet 1 that contains a considerable part of the arrangement according to the invention. The cabinet 1 comprises at its top a receiver, formed of a principally plane reception board 2, onto which food waste can be tipped for its processing and transport with the aid of the treatment arrangement according to the invention. To the left of the reception board 2, the receiver comprises further a protective hood 3 that covers a feed funnel 4 that can lead food waste to a mill 5 arranged in the cabinet. There is an opening, not shown in the drawings, in the protective hood 3, the lower edge of which lies in line with the surface of the reception board 2 such that the food waste can be displaced in through the opening in the protective hood 3, and thus enter the feed funnel 4 that is located underneath it. It is appropriate that the feed funnel comprise a labyrinthine inlet, such that it is not possible to insert a hand through the opening in the protective hood 3 and onwards down into the feed funnel 4.

There is arranged under the feed funnel 4 in the cabinet 1 also a food waste processor that comprises a mill 5 and a pump 8. The lower outlet of the feed funnel 4 is connected to the inlet to the mill 5. The mill 5 is a normal waste disposal mill of the type that is used mounted for connection to the normal waste water system, and is thus an electrically driven mill that can break food waste up into smaller parts, and the mill is connected to an outlet pipe 6 through which the milled food waste can be taken onwards to the inlet 7 to the pump 8 that is arranged at the bottom of the cabinet 1. The pump 8 is driven by an electric motor 9 that also is located in the cabinet 1, and the pump further has a pump component 10 that extends out of the cabinet. A pump outlet 11 is located at the outermost end of this pump component 10. The pump 8 is an eccentric screw pump, but it is obvious that it would be possible to use also other types of pump if they have the capacity to pump a material that may have considerably varying consistency or viscosity. The food waste may be anything from a thin soup to rather compact food waste such as, for example, glutinous rice. An eccentric screw pump has excellent properties in this respect and can pump very thin fluid up to a considerable height above the location of the pump, and it has also the ability to pump thick material in this manner, and in both cases this can take place over a long distance.

The pump outlet 11 of the pump 8 is, as is shown in Figure 2, connected to a transport line 12 that can lead the food waste that has been output from the pump onwards to a waste tank 13, which is appropriately located outside of the building in which the rest of the treatment arrangement according to the invention is located. The tank 13 may be, as is suggested in Figure 2, located at a level that lies higher than that on which the cabinet 1 with the mill 5 and the pump 8 are located, and in this case, it is thus necessary that the transport line 12 be drawn up to such a height that the food waste can be fed into the tank 13 from above. It is, of course, also possible that the tank 13 be located at a level under the cabinet 1, such as in the case in which, for example, the tank has been buried under the ground level of the building in which the cabinet with the mill 5 and the pump 8 are located. Further, it is possible also to place the food waste tank 13 indoors, and in such a case not only on the same storey as the cabinet 1 with the mill 5 and the pump 8, but also on a higher or lower storey.

Switches 15 are arranged on the front panel of the cabinet 1 in order to start or stop the mill 5 and the pump 8, and it is appropriate that these are connected such that they are started and stopped at the same time. It is possible to remove the protective hood 3 over the feed funnel 4 and the mill 5 in order to make it possible to clean the funnel and the mill, and to remove any objects that have become stuck. In order to ensure that nobody can insert the hands into the mill 5 when it is in operation, it is appropriate that the protective hood 3 be provided with a safety switch that ensures that the mill and the pump are stopped as soon as the protective hood 3 is removed from the cabinet 1. It is appropriate for cleaning purposes that the protective hood be attached to the cabinet 1 and the feed funnel 4 with the aid of knurled screws such that it can be easily removed by hand. In order for the pump 8 of preferred type to function correctly, the dry matter content of the material must not be too high. In order to ensure that this is not the case, the treatment arrangement according to the invention is provided with a supply of water, where there is arranged at the outer surface for the cabinet a water connection 16, and internally in the cabinet 1 there is drawn a supply line that opens out into a water outlet in the feed funnel 4. Alternatively, the water outlet may open out into a hole in the protective hood 3, which causes a protective air gap to form at the funnel 4, which is often required by local regulations. The supply of water, however, ensures that also "dry" food waste with a very limited water content can be pumped via the transport line 12 to the food waste tank 13. It is appropriate that there is arranged in the cabinet also a pause and run time relay that can control the supply of water to the feed funnel 4 such that the supply of water takes place intermittently, for example in the form of a pulse function, that supplies water during a period of, for example, 3 seconds per 15- second period. It is appropriate that on the front panel 14 of the cabinet there is arranged a contact 17 with which it is possible to activate an extra supply of water for food waste with a high viscosity. It is appropriate that the contact 17 be provided with an indicator lamp that shows also when the supply of water that is activated by the time relay is active, in order in this way to be able to monitor that it is functioning as intended. It is appropriate also that it is possible to set the length of pulse in the relay, such that it is possible to adjust the supply of water according to what is normally needed. It is important not to supply too much water, since this is fed out together with the food waste to the closed tank 13, and contributes to filling this, whereon the frequency at which the tank 13 is filled increases, which leads to increased operating costs for the emptying .

The preferred pump 8 cannot either deal with too high a temperature of the material that it is to feed. Therefore, there is arranged also a temperature sensor at the pump in order to monitor its temperature, and it is appropriate that this temperature is displayed also on a digital display 18 on the front panel 14 of the cabinet 1. It is appropriate also that the temperature sensor be connected to an automatic switch that stops the pump 8 and the mill 5 if the temperature of the pump exceeds a certain predetermined temperature. An operator can also, with the aid of the digital display 18, monitor the temperature, and if it approaches the highest allowed temperature activate the manual supply of water with the aid of the contact 17, and in this way cause a fall in temperature in the pump 8. It may be arranged also that the predetermined temperature value of the temperature sensor activates automatically with the aid of a relay the supply of water in order to reduce the temperature in the pump 8. The temperature in the pump depends to a large extent on the temperature of the food waste that is milled down with the aid of the mill 5 and that is to be removed by the pump 8.

It may be appropriate that a stop valve is arranged in the transport line 12 in the vicinity of the pump 8, such that the pump can be disconnected for, for example, service, without food waste running back through the transport line and out onto the floor.

The tank 13 is, as has been mentioned, a closed tank, which means that it needs to be emptied as it becomes close to becoming full. It is appropriate that the emptying take place by a slurry tanker, which can withdraw by suction the contents of the tank 13 and transport it onwards to a facility for digestion and the production of biogas. A level monitor, for example one or, preferably, two floats, is connected to the tank in order to be able to check the level in it. One of the floats can in this case be adjusted such that it indicates when the tank is 75% full, and the second float when the tank is 90% full. It is appropriate that these indications are shown with the aid of an indicator arrangement, for example a pair of control lamps 19 on the front panel 14 of the cabinet 1. One of the control lamps may, for example, be yellow in order to indicate a degree of filling of 75%, and the second red in order to indicate a filling level of 90%. The latter may be also connected to the control of the treatment arrangement, such that both the mill 5 and the pump 8 are stopped when the highest permitted level in the tank 13 has been reached.

The transport line 12 that connects the pump outlet 11 of the pump 8 to the tank 13 should be without sudden bends, in order to reduce the resistance in the transport line and ensure safe pumping of the food waste. It is preferable that the bends formed by angular bends have a maximum angle of 45°, and in order to achieve a bend in the pipe of 90° two 45° angular bends are connected one after the other, preferably with a short straight intermediate piece between them, as is suggested in Figure 2. The transport lines may be of polyethylene or of corrosion-resistant stainless steel. In the case in which the transport line 12 in its route to the tank is located outdoors in a position where there is a risk that the contents of the transport line freeze, the transport line is supplemented with some form of heating or insulation, or heating and insulation, in order to remove this risk.

It is appropriate that the cabinet 1 and its external parts, such as the reception board 2, the protective hood 3 and the front panel 14, as also the side and back panels, are of stainless steel. As is made clear by Figure 1, also a protective plate 20 is arranged at the side and back of the reception board 2, which plate extends up over the reception board, and also this protective plate is preferably of stainless steel. This protective plate 20 prevents food waste falling over the edge of the reception board 2 and falling onto the floor.

Claims

1. An arrangement for the treatment of food waste, in particular for the treatment of food waste in industrial kitchens (not only on land but also at sea) , restaurant kitchens, the foodstuffs industry, the retail grocery industry, and similar, characterised in that the arrangement comprises a receiver (2, 3, 4) for the food waste, a mill (5) connected to the receiver in order to mill down the food waste to the intended maximum waste size, an eccentric screw pump (8) arranged after the mill (5) and arranged to pump via a transport line (12) the milled food waste to a food waste tank (13) , in which the food waste can be stored while waiting for removal.

2. The arrangement according to claim 1, characterised in that the receiver (2, 3, 4), the mill (5) and the pump (8) are arranged in one common unit (1) .

3. The arrangement according to claim 1 or 2, characterised in that a connection to a water supply line is arranged in order to supply water as necessary to at least one of the mill (5) and the pump (8) in order to be able to pump the food waste via the transport line (12) to the food waste tank (13) .

4. The arrangement according to claim 3, characterised in that a pause and run time relay is arranged in order to activate the addition of water at predetermined intervals.

5. The arrangement according to claim 3, characterised in that a temperature sensor is arranged at the pump in order to register its temperature, and in that a relay is arranged to activate, in the event of the temperature exceeding a predetermined temperature, the supply of water to the pump

(8) in order to cool it, or alternatively, to switch the pump

(8) off.

6. The arrangement according to claim 3, characterised in that a contact (17) is arranged for the manual activation of the supply of water.

7. The arrangement according to any one of the preceding claims, characterised in that the tank (13) is provided with a level sensor that is connected to an indicator arrangement (19) in order to indicate that the tank (13) requires emptying .

8. The arrangement according to claim 7, characterised in that the indicator arrangement (19) is arranged such that in the event that a predetermined highest level in the tank (13) is reached it stops both the mill (5) and the pump (8) .