HYDRAULIC CONVEYOR OF FLOATING OBJECTS PROVIDED WITH A DEVICE FOR SANITISING CONVEYING COMPOSITION, PLANT PROVIDED WITH SUCH A CONVEYOR AND SANITISING METHOD

Abstract

A hydraulic conveyor for floating objects, having recirculation of a liquid composition, named conveying composition, for conveying the floating objects, includes at least one device for sanitizing the conveying composition. The sanitizing device includes: at least one device irradiating a composition, named composition to be sanitized, formed by mixing at least some of the conveying composition and an amount of a composition, named photoreactive composition, including at least one photosensitive compound that forms, under the effect of irradiation by the irradiation device, at least one compound, named active compound, transforming by chemical reaction at least one pollutant compound of the conveying composition into a non-pollutant compound; and at least two photolysis chambers mounted in series such that the composition to be sanitized can flow successively into the at least two photolysis chambers, at least one irradiation device being arranged in an inner volume of each photolysis chamber.

Claims

1. Hydraulic conveyor for floating objects selected from the group formed of fruit and vegetables, of the type having recirculation of a liquid composition, named conveying composition, for conveying the floating objects, said hydraulic conveyor being provided with at least one device (13) for sanitising said conveying composition; wherein at least one sanitising device (13) comprises: at least one irradiation device arranged to be able to irradiate a composition, named composition to be sanitised, formed by mixing at least some of said conveying composition and an amount of a composition, named photoreactive composition, comprising at least one photosensitive compound selected to be able to form, under the effect of irradiation by at least one irradiation device, at least one compound, named active compound, able to transform by chemical reaction at least one pollutant compound of said conveying composition into a non-pollutant compound; and at least two photolysis chambers (1) mounted in series such that said composition to be sanitised can flow successively into said at least two photolysis chambers (1), at least one irradiation device being arranged in an inner volume of each photolysis chamber.

2. Conveyor according to claim 1, wherein at least one sanitising device (13) is adapted to have a flow of composition to be sanitised pass through it and to allow the irradiation of the composition to be sanitised by at least one irradiation device between an inlet for a flow of composition to be sanitised drawn into a hydraulic channel of the conveyor, and an outlet for the flow of composition, named sanitised composition, directed towards a hydraulic channel of the conveyor.

3. Conveyor according to claim 1, further comprising at least one circulation pump (14) for composition to be sanitised formed from the conveying composition in the sanitising device (13).

4. Conveyor according to claim 1, further comprising a device for mixing conveying composition and photoreactive composition upstream of the sanitising device.

5. Conveyor according to claim 1, further comprising a pump (19) for distributing photoreactive composition into said conveying composition.

6. Conveyor according to claim 1, wherein at least one photolysis chamber (1) is in the shape of a cylinder of revolution and includes a plurality of light sources (5) in the form of tubes, each light source (5) extending in parallel with the longitudinal axis of said photolysis chamber (1) and facing one another, the plurality of light sources (5) being distributed in said photolysis chamber (1) so as to be positioned at the points of a regular polygon, as seen in any cross-section of said photolysis chamber (1).

7. Conveyor according to claim 6, wherein the light sources (5) of the plurality of light sources are uniformly distributed in the inner volume of said photolysis chamber (1).

8. Conveyor according to claim 6, wherein the sanitising device (13) comprises an inlet for photoreactive composition located upstream of a first chamber of the plurality of photolysis chambers (1).

9. Plant for sorting floating objects comprising at least one hydraulic conveyor according to claim 1.

10. Method for sanitising a liquid composition, named conveying composition, for conveying floating objects selected from the group formed of fruit and vegetables, of a hydraulic conveyor of the type having recirculation of said conveying composition, wherein: at least some of said conveying composition is mixed with an amount of composition, named photoreactive composition, comprising at least one photosensitive compound selected to be able to form, under the effect of irradiation by at least one irradiation device, at least one compound, named active compound, able to transform by chemical reaction at least one pollutant compound of said conveying composition into a non-pollutant compound; and this mixture, named composition to be sanitised, is subjected to this irradiation so as to form an at least partially sanitised composition; wherein said composition to be sanitised is subjected to this irradiation in a sanitising device (13) which has a flow of said composition to be sanitised passing through it, the sanitising device (13) comprising at least two photolysis chambers (1) mounted in series such that said composition to be sanitised flows successively into said at least two photolysis chambers (1), at least one irradiation device being arranged in an inner volume of each photolysis chamber (1).

11. Method according to claim 10, wherein at least one photosensitive compound is hydrogen peroxide.

12. Method according to claim 10, wherein the irradiation is illumination by ultraviolet light radiation.

13. Method according to claim 10, wherein the amount of said photoreactive composition and irradiation conditions are adapted such that said sanitised conveying composition has a residual amount of photosensitive compound which is less than a predetermined maximum amount allowed by regulations.

14. Method according to claim 10, wherein at least one pollutant present in said conveying composition is a pesticide of the group formed of fungicides, bactericides and insecticides.

15. (canceled)

16. The conveyor of claim 6, wherein each photolysis chamber is in the shape of a cylinder of revolution and includes a plurality of light sources in the form of tubes.

17. Conveyor according to claim 2, further comprising at least one circulation pump (14) for composition to be sanitised formed from the conveying composition in the sanitising device (13).

18. Conveyor according to claim 2, further comprising a device for mixing conveying composition and photoreactive composition upstream of the sanitising device.

19. Conveyor according to claim 3, further comprising a device for mixing conveying composition and photoreactive composition upstream of the sanitising device.

20. Conveyor according to claim 2, further comprising a pump (19) for distributing photoreactive composition into said conveying composition.

21. Conveyor according to claim 3, further comprising a pump (19) for distributing photoreactive composition into said conveying composition.

Description

[0080] Other aims, features and advantages of the invention will become apparent upon reading the following description given solely by way of non-limiting example and which makes reference to the attached figures in which:

[0081] FIG. 1 is an overall view of a photolysis chamber of a sanitising device in accordance with the invention;

[0082] FIG. 2 is a top view of a photolysis chamber of a sanitising device in accordance with the invention;

[0083] FIG. 3 is a schematic view of a sanitising device in accordance with a first aspect of the invention;

[0084] FIG. 4 is a schematic view of a sanitising device in accordance with another aspect of the invention;

[0085] FIG. 5 is a graph of the neutralisation of boscalid by a variant of a method in accordance with the invention;

[0086] FIG. 6 is a graph of the neutralisation of four pesticides by a method in accordance with the invention; and

[0087] FIG. 7 is a graph of the neutralisation of boscalid by the implementation of a variant of a method in accordance with the invention.

[0088] A photolysis chamber 1 of a device for sanitising a conveying composition of a hydraulic conveyor in accordance with one embodiment of the invention is shown in FIG. 1. This photolysis chamber 1 comprises a rigid cylindrical body 2. The cylindrical body 2 is hollow and liquid-tight and is of the type allowing circulation of an aqueous liquid composition within the cylindrical body between an inlet 3 for composition to be sanitised and an outlet 4 for sanitised composition, having a lesser amount of pollutant compounds than the composition to be sanitised, in particular substantially free of pollutant compounds. The inlet 3 for composition to be sanitised is in fluid communication with a hydraulic channel of a hydraulic conveyor for conveying floating objects such as fruit or vegetables of a plant for sorting and packaging such products. The outlet 4 for sanitised composition is in fluid communication with this same hydraulic channel such that the conveying composition can be indefinitely recycled in the hydraulic conveyor in accordance with the invention. Said photolysis chamber 1 allows the conveying composition of the hydraulic conveyor in accordance with the invention to be recycled in a closed circuit. Said photolysis chamber 1 allows the conveying composition of the plant to be sanitised by illuminating the conveying composition flowing in said photolysis chamber 1. The photolysis chamber 1 comprises at least one light source 5 arranged in an inner space of the cylindrical body 2 and in contact with the composition to be sanitised flowing in said photolysis chamber 1.

[0089] The photolysis chamber 1 also shown in FIG. 2 has five light sources formed from light tubes distributed in the inner space of the cylindrical body 2, the five light tubes extending in parallel with each other in the inner space and substantially in parallel with the longitudinal axis of the cylindrical body 2. Advantageously, the five light tubes are distributed with respect to each other in the inner space of the cylindrical body 2 such that each light tube is positioned at the point of a regular pentagon, as seen in any cross-section of the cylindrical body 2. In this particular configuration, the light tubes allow optimum illumination of the composition to be sanitised passing through the photolysis chamber 1 in a flow oriented in parallel with the longitudinal axis of the cylindrical body 2.

[0090] A device 13 for sanitising a composition for conveying floating objects such as fruit or vegetables is shown schematically in FIG. 3, coupled to a hydraulic conveyor in accordance with the invention. Such a conveyor comprises a container 10 for conveying floating objects in which products such as fruit or vegetables are conveyed whilst floating. The container 10 can be a hydraulic channel for conveying floating objects extending in part upstream of a plant for sorting and packaging fruit and vegetables or a hydraulic channel for conveying sorted floating objects extending in part downstream of the plant for sorting and packaging fruit and vegetables. It can also be a hydraulic conveyor for floating objects such as floating fruit or vegetables to a plant for sorting and packaging said products. The container 10 is sized in accordance with the size of the plant for sorting and packaging floating objects such as fruit and vegetables, in accordance with the number and dimensions of the hydraulic channels of the plant. Such a container 10 can contain, for example, a volume of conveying composition between 10 m.sup.3 and 1000 m.sup.3, in particular in the order of 90 m.sup.3 to 100 m.sup.3.

[0091] The container 10 has an orifice 11 for drawing a composition to be sanitised and an orifice 12 for recycling a sanitised composition in the container 10. The sanitising device 13 extends between the drawing orifice 11 and the recycling orifice 12 of the container 10 and forms a circuit external to the container 10. The sanitising device 13 comprises a pump 14 for circulating the composition to be sanitised adapted to be able to draw said composition to be sanitised from the drawing orifice 11 of the container 10, cause the composition to be sanitised to flow in an external circuit to a photolysis chamber 1 and pump the sanitised composition into the recycling orifice 12 of the container 10. The circulation pump 14 is adapted to be able to control the flow rate of composition to be sanitised to be a predetermined value. For example, the flow rate of the circulation pump 14 can vary between several m.sup.3/h and 100 m.sup.3/h.

[0092] The sanitising device 13 comprises a plurality of photolysis chambers (indicated by reference numeral 1) comprising at least one light source able to illuminate the composition to be sanitised flowing in each photolysis chamber. Each photolysis chamber has an inner volume in the order of 30 to 40 litres and five fluorescent tubes, 254 nm, with a power of 200 watts able to provide an irradiation intensity to the composition to be sanitised of a value in the order of 500 mJ/cm.sup.2 with a flow rate of the composition to be sanitised of a value in the order of 6 m.sup.3/h in each photolysis chamber. Other values are possible.

[0093] The sanitising device 13 also comprises a path 16 for introducing a photoreactive composition into the external circuit. The introduction path 16 preferably issues into the external circuit via an inlet 17 for photoreactive composition positioned upstream of the plurality of photolysis chambers such that the introduction of the photoreactive composition into the conveying composition forms the composition to be sanitised close to an inlet 18 for composition in the plurality of photolysis chambers. The photoreactive composition comprises at least one photosensitive compound able to form, in the composition to be sanitised, at least one chemical species which can react with at least one pollutant present in the conveying composition under the effect of illumination by the light source(s). The introduction path 16 comprises a pump 19 for distributing the photoreactive composition in the external circuit and in the plurality of photolysis chambers.

[0094] The distribution pump 19 of the sanitising device 13 thus allows the adjustment of the flow rate of photoreactive composition to be introduced into the flow of conveying composition drawn from the container 10 so as to form a flow of composition to be sanitised in the plurality of photolysis chambers and to allow decontamination of the composition to be sanitised and the formation of a sanitised composition exiting the plurality of photolysis chambers.

[0095] The sanitised composition is reintroduced into the container 10 under the effect of the circulation pump 14. The sanitised composition further has a concentration of photosensitive compoundin particular of hydrogen peroxidelower than the maximum concentration allowed by regulations for the use of the sanitised composition in contact with food products. The flow rate of the recirculation pump 14 is adjusted with respect to the volume of the container 10 and the flow rate of the pump 19 for distributing the photoreactive composition such that the proportion of pollutant in the conveying composition is kept at a low value which is acceptable for its use in contact with food products.

[0096] A hydraulic conveyor in accordance with the invention shown schematically in FIG. 3 also has a drain valve 20 of the hydraulic conveyor. It also has a drain valve 21 of the plurality of photolysis chambers allowing the implementation of servicing and maintenance operations on the plurality of photolysis chambers. A hydraulic conveyor in accordance with the invention shown schematically in FIG. 3 also has valves 22, 23 for adjusting the flow rate of the flow of conveying composition in the sanitising device 13.

[0097] Another embodiment of a device 131 for sanitising a composition for conveying floating objects such as fruit or vegetables is shown schematically in FIG. 4. In FIG. 4, the hydraulic conveyor in accordance with the invention is not shown in its entirety.

[0098] The sanitising device 131 extends between an orifice 111 for drawing conveying composition in a hydraulic channel for conveying floating objects of a hydraulic conveyor and an orifice 121 for recycling sanitised conveying composition in a hydraulic channel of the hydraulic conveyor. The sanitising device 131 comprises a plurality of photolysis chambers 1 mounted in series and allowing the composition to be sanitised to flow successively into each photolysis chamber 1 in which it is irradiated.

[0099] Each photolysis chamber 1 comprises at least one light source able to illuminate the composition to be sanitised flowing in the sanitising device 131. Each photolysis chamber 1 can be of the type described in FIG. 1 and FIG. 2. Each photolysis chamber has for example an inner volume in the order of 30 to 40 litres and five fluorescent tubes, 254 nm, with a power of 200 watts able to provide an irradiation intensity to the composition to be sanitised of a value in the order of 500 mJ/cm.sup.2 with a flow rate of the composition to be sanitised of a value in the order of 6 m.sup.3/h in each photolysis chamber 1. Other values are possible.

[0100] The sanitising device 13 also comprises a path 161 for introducing a photoreactive composition upstream of the sanitising device 131. The introduction path 161 preferably issues into the sanitising device 131 via an inlet 171 for photoreactive composition positioned upstream of the first (upstream) photolysis chamber 1 such that the mixing of the photoreactive composition in the conveying composition forms the composition to be sanitised close to an inlet 181 for composition in the upstream photolysis chamber 1. The introduction path 161 comprises a pump 191 for metering (distributing) the photoreactive composition in the sanitising device 131 and in the upstream photolysis chamber 1.

EXAMPLE 1

[0101] A flow rate of conveying composition of 6 m.sup.3/h is established in the external circuit and a flow rate of photoreactive composition of 3 dm.sup.3/h is established, the photoreactive composition being an aqueous solution of hydrogen peroxide at an initial concentration of 4 g/l. The thereby obtained composition to be sanitised thus has a hydrogen peroxide proportion in the order of 2 ppm and is sufficient to allow the decontamination of the composition to be sanitised exiting the photolysis tank formed of a single photolysis chamber comprising five fluorescent tubes with an individual power of 200 W.

EXAMPLE 2

[0102] A hydraulic conveyor of a plant for sorting and packaging apples is selected containing a volume of 90 m.sup.3 of a conveying composition containing BELLIS at a concentration of 50 m g/l (and boscalid at a concentration of 22 g/l). A flow rate of the conveying composition of 36 m.sup.3/h is established in the external circuit using the circulation pump 14 and a flow rate of photoreactive composition of 270 cm.sup.3/h is established using the distribution pump 19, the photoreactive composition being an aqueous solution of hydrogen peroxide at an initial concentration of 400 g/l, i.e. 108 g or pure hydrogen peroxide. Under these conveying composition flow conditions, all of the volume of the conveying composition contained in the plant is theoretically treated within 2.5 hours. The composition to be sanitised obtained at the inlet of the sanitising device thus has an initial hydrogen peroxide proportion in the order of 3 ppm and is sufficient to allow the decontamination of the composition to be sanitised at the outlet of the sanitising device formed of 6 photolysis chambers mounted in series, each chamber comprising five fluorescent tubes with an individual power of 200 W.

[0103] The results obtained are shown in Table 1 hereinafter in which the concentration values of boscalid in the composition to be sanitised at the inlet of the photolysis tank (EC), at the outlet of the third chamber (S3E) of the photolysis tank and at the outlet of the sixth chamber (S6E) of the photolysis tank are given in g/l. The column S6E/EC represents the ratio multiplied by 100 of the boscalid concentration at the outlet of the sixth chamber (S6E) of the photolysis tank to the boscalid concentration at the inlet of the photolysis tank (EC). The column C/C.sub.0represents the ratio of the boscalid concentration measured at the inlet of the photolysis tank over time to the initial boscalid concentration (t=0).

TABLE-US-00001 TABLE 1 Boscalide, g/l Time, hours EC S3E S6E S6E/EC, % C/C.sub.0 0 21.43 1.25 16.64 1.28 92 0.79 2.5 15.68 3.96 0.99 94 0.73 3.75 15.56 3.38 0.91 94 0.73 5 14.06 2.71 0.56 94 0.66 7.5 8.25 1.78 0.38

[0104] The rate of degradation of the boscalid between the inlet and outlet of the photolysis tank is high and is greater than 90%. This treatment allows the elimination of 62% of the boscolid of the conveying composition of the hydraulic conveyor within 7.5 hours.

EXAMPLE 3

[0105] A hydraulic conveyor of a plant for sorting and packaging apples is selected containing a volume of 90 m.sup.3 of water as composition for conveying Ariane, Rosy Glow and Pink Lady apples. A flow rate of conveying composition of 36 m.sup.3/h is established in the external circuit and a flow rate of photoreactive composition of 2.8 to 3.5 dm.sup.3/h is established, the photoreactive composition being an aqueous solution of hydrogen peroxide at an initial concentration of 400 g/l. Under these flow conditions, all of the volume of the conveying composition of the hydraulic conveyor is theoretically treated within 2.5 hours. The composition at the inlet of the sanitising device has an initial hydrogen peroxide proportion in the order of 3 ppm sufficient to allow the decontamination of the composition at the outlet of the sanitising device formed of six photolysis chambers mounted in series, each chamber comprising five fluorescent tubes with an individual power of 200 W. The results obtained are shown in Table 2 hereinafter in which the concentration values of boscalid from the apples conveyed with the composition to be sanitised at the inlet of the sanitising device (EC) and at the outlet of sanitising device (SC) are given in g/l. The column SE/EC represents the ratio multiplied by 100 of the boscalid concentration at the outlet of the sixth chamber of the photolysis tank to the boscalid concentration at the inlet of the photolysis tank (EC). The column C/C.sub.0 represents the ratio of the boscalid concentration measured at the inlet of the sanitising device over time to the initial boscalid concentration (t=0).

TABLE-US-00002 TABLE 2 Boscalide, g/l Time, hours EC SC SC/EC, % C/C.sub.0 0 2.83 100 4 4.76 0.065 98.6 7 2.84 0.206 92.8 7.1 4.19 100 1 10.5 1.73 0.062 96.4 0.41 12.5 1.35 100 0.32 14.75 1.71 0.058 96.6 0.41 17.25 1.18 0.040 96.6 0.28 19.25 1.88 100 0.45 22.75 1.07 0.064 94 0.25 24.75 0.64 0.057 91.2 0.15 28.75 0.66 0.039 94 0.16 29.75 0.93 100 0.22 32.25 0.79 0.040 95 0.19 34.75 0.73 0.043 94.1 0.17

[0106] Between 90% and 100% of the boscalid of the conveying composition is eliminated during this treatment.

EXAMPLE 4

Semi-Industrial Pilot Device

[0107] A semi-industrial pilot device in accordance with one aspect of the invention comprises a tank for recirculating water to be treated of a volume of 1000 1, a circulation pump ensuring a circulation flow of the water to be treated in a sanitising device with a flow rate between 4 m.sup.3 to 8 m.sup.3/h. The sanitising device comprises a photolysis chamber comprising an inlet for water from the recirculation tank and an outlet for sanitised water directed to the recirculation tank. The photolysis chamber is formed of a rigid tubular envelope, of which the external wall is opaque to light and forming an inner space suitable for receiving five fluorescent tubes with a longitudinal axis extending in parallel with the longitudinal axis of the rigid tubular envelope. The inner volume of the decontamination reactor is in the order of 321.

[0108] The five fluorescent tubes are tubes of 200 W emitting light at a wavelength of 254 nm and arranged longitudinally in the tubular envelope at the five points of a regular pentagon and in contact with the water to be treated flowing in the photolysis chamber. In this configuration of the sanitising device, the water to be sanitised flowing in contact with the five fluorescent tubes is subjected to substantially homogeneous illumination in the order of 500 mJ/cm.sup.2 for a circulation flow rate of water to be sanitised in the order of 6 m.sup.3/h. The semi-industrial pilot device also comprises a tank for storing an aqueous solution of hydrogen peroxide (H.sub.2O.sub.2) provided with a pump for distributing said solution in the circulation flow of water to be sanitised issuing into the circuit of water to be sanitised upstream of and in proximity to the photolysis chamber. The concentration of the hydrogen peroxide in the aqueous solution of hydrogen peroxide is between 2 m g/l and 13 mg/l. The set-point flow rate of the pump for distributing solution of H.sub.2O.sub.2 is kept at 4 l/h.

[0109] FIG. 5 shows the change in the ratio of the value of the boscalid concentration in the recirculation tank to the value of the initial boscalid concentration in the recirculation tank. The flow rate of the recycling pump is 6 m.sup.3/h and the initial boscalid concentration in the recirculation tank is 250 g/l. The 5 lamps of the sanitising device are switched on. Under illumination and in the absence of hydrogen peroxide (curve designated by the symbols .square-solid.), the degradation of the boscalid is limited and reaches 10% of the initial boscalid after one hour of treatment. The initial addition (curve designated by the symbols *) of hydrogen peroxide at a concentration of 13 mg/l, or the successive addition (curve designated by the symbols .circle-solid.) of 3 doses of hydrogen peroxide at a concentration of 13 mg/l does not have a major difference on the final rate (95%) of degradation of the boscalid. The continuous addition (curve designated by the symbols .box-tangle-solidup.) of hydrogen peroxide at a concentration of 2 mg/l provides an initial degradation of the boscalid equivalent to that obtained with the addition of hydrogen peroxide at the concentration of 13 mg/l. The interruption of this addition (between 10 min and 25 min) results in the degradation of the boscalid stopping, showing the total and rapid consumption of the hydrogen peroxide in the conveying composition. Re-starting the addition of hydrogen peroxide at the concentration of 2 mg/l results in the degradation of the boscalid starting again in the conveying composition.

EXAMPLE 5

Sanitisation with Respect to Different Pesticides

[0110] A study was carried out in a semi-industrial pilot device as described above on the degradation of boscalid, thiacloprid, fludioxonil and pyraclostrobin. The flow rate of the conveying composition provided by the recirculation pump is 6 m.sup.3/h. The initial boscalid concentration in the recirculation tank is 250 g/l. The initial thiacloprid concentration in the recirculation tank is 100 g/l. The initial fludioxonil concentration in the recirculation tank is 100 g/l. The initial pyraclostrobin concentration in the recycling tank is 125 g/l. The initial hydrogen peroxide concentration in the composition to be sanitised is 2 g/l. The five lamps of the photolysis chamber are switched on. The results are shown in FIG. 6 which shows that the boscalid (.box-tangle-solidup.) is degraded to 70% within 1 hour, the pyraclostrobin (.circle-solid.) is degraded to 85% within 1 hour, the fludioxonil (.square-solid.) is degraded to 90% within 1 hour and the thiacloprid (*) is degraded to more than 95% within 1 hour.

EXAMPLE 6

Sanitisation with Respect to Different Amounts of Boscalid

[0111] A study was carried out in a semi-industrial pilot device as described above on the degradation of boscalid at concentrations of 25 g/l, 80 g/l and 200 g/l. The flow rate of the conveying composition provided by the recycling pump is 6 m.sup.3/h. An aqueous solution of hydrogen peroxide is continuously added upstream of the sanitising device such that the initial hydrogen peroxide concentration in the composition to be sanitised is 2 mg/l. The results are shown in FIG. 7 in which the dashed curve (---) represents a treatment by illumination, the curve designated by (*) represents a treatment with just hydrogen peroxide, i.e. without illumination at 254 nm, the curve (.square-solid.) represents a treatment of a composition to be sanitised comprising boscalid at a concentration of 25 g/l, the curve () represents a treatment of a composition to be sanitised comprising boscalid at a concentration of 80 g/l and the curve (.box-tangle-solidup.) represents a treatment of a composition to be sanitised comprising boscalid at a concentration of 200 g/l. A residual amount of boscalid of less than 80% is obtained.

[0112] EXAMPLE 7

Advantages Provided by a Method and a Device for Decontamination in Accordance with the Invention

[0113] A comparative study of the impact provided by exposing the Xenopus laevis amphibian model to a conveying composition comprising boscalid, sanitised or not by a decontamination method in accordance with the invention has been carried out. It was observed that a conveying composition initially comprising boscalid and sanitised by a decontamination method in accordance with the invention does not result in death (as measured in accordance with the standard OCDE 203, 1992) on the larvae of the Xenopus laevis amphibian biological model which were in contact with such a composition for 96 hours or for 12 days. Furthermore, it has been observed that a conveying composition initially comprising boscalid and sanitised by a decontamination method in accordance with the invention does not cause permanent damage to the DNA of the Xenopus laevis amphibian biological model in contact with such a composition for 12 days (in accordance with the standard ISO 21427-1, 2006), contrary to a conveying composition comprising boscalid and not sanitised by a decontamination method in accordance with the invention which results in the formation of micronuclei in the larvae of this amphibian.

EXAMPLE 8

Comparative Test

[0114] A comparative test performed with a semi-industrial pilot device as decribed in Example 4 and a sanitising device in accordance with the invention of a hydraulic conveyor of a plant for sorting and packaging apples as described in Example 3 was carried out.

[0115] The semi-industrial pilot device comprises a tank for composition to be treated of a volume of 1000 1, a circulation pump ensuring a flow of composition to be treated in a sanitising device with a flow rate of 6 m.sup.3/h. The sanitising device comprises a single photolysis chamber comprising an inlet for water from the tank of composition to be treated and an outlet for sanitised water directed to the tank of composition to be treated. The composition to be treated comprises boscalid at an initial concentration of 25 g/l and an initial hydrogen peroxide concentration of 2 mg/l.

[0116] The photolysis chamber is formed of a rigid tubular envelope, of which the external wall is opaque to light and forming an inner space suitable for receiving five fluorescent tubes with a longitudinal axis extending in parallel with the longitudinal axis of the rigid tubular envelope. The inner volume of the decontamination reactor is in the order of 32 1. The five fluorescent tubes are tubes of 200 W emitting light at a wavelength of 254 nm and arranged longitudinally in the tubular envelope at the five points of a regular pentagon and in contact with the water to be treated flowing in the photolysis chamber.

[0117] After 10 minutes of operation of the semi-industrial pilot device, almost all of the composition to be treated has been illuminated in the photolysis chamber. The rate of degradation of the boscalid is 58% of the initial boscalid after 10 minutes of operation of the semi-industrial pilot device.

[0118] A hydraulic conveyor of a plant for sorting and packaging apples containing a volume of 90 m.sup.3 of water as composition for conveying Ariane, Rosy Glow and Pink Lady apples comprises a sanitising device in accordance with the invention formed of six photolysis chambers mounted in series, each chamber comprising five fluorescent tubes having an individual power of 200W. The flow rate of the composition for conveying apples in the sanitising device is 36 m.sup.3/h. It has been observed that the plurality of photolysis chambers mounted in series allows a rate of degradation of 96% of the initial boscalid to be achieved with a flow rate of the composition to be treated of 36 m.sup.3/h and for an average residence time of the conveying composition in the sanitising device in the order of 19 seconds.

[0119] It goes without saying that the invention can cover numerous embodiment variants and applications. In particular, a hydraulic conveyor, a sanitising device and a sanitising method in accordance with the invention are subject to an infinite number of variants in the implementation of such a hydraulic conveyor and in its application to floating fruit and/or vegetables.