NZ282204A - Process for treating fresh produce to remove and inhibit fungus growth using water and chlorine dioxide solution - Google Patents

Description

9 New Zealand No 282204 International No PCT/US95/02128 TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates 17 02 1995 Complete Specification Filed 17 02 1995 Classification (6) A23B7/14.153 Publication date 29 Apnl 1999 Journal No 1439 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention Method for treating produce and process water Name, address and nationality of applicant(s) as in international application form CH20 INCORPORATED, 8820 Old Highway 99 S E , Olympia, Washington 98501, United States of America WO 96/23049 PCT/US95/02128 Description METHOD FOR TREATING PRODUCE AND PROCESS WATER Technical Field This invention relates to a method for treating contaminants in process water and treating produce to remove debris, organic chemicals, and hard water deposits from the produce and inhibit the formation of mold on the produce, and more particularly, to a method of treating contaminants in 10 process water and cleaning, sanitizing, and descaling produce by the use of an effective amount of a chlorine dioxide solution.

Background Information After harvest, fresh produce is washed before being sorted and packed Once clean produce has been sorted and packed, fungus adhering to the surface of the produce may cause mold to develop before the produce has reached market The presence of fungus on ev«n one piece of produce in a crate can cause 20 decay of substantially all of the produce m the crate For these reasons, it is desirable to reduce the occurrence of decay in packed produce so that the overall value of the harvested produce is increased If produce is treated by process water, the used process 25 water contains contaminants and debris Conventionally, process water for treating produce has been used for a short time before being dumped due to tb» buildup of contaminants m the process water 3 0 Disclosure of the Invention The present mventior provides a method for treating process water and an object submerged in process water when the process water and the object include at least one contaminant from the group of debris, soil, fungus, and organic chemicals 35 The method comprises immersing the object in the process water Then, a chlorine dioxide solution is generated An effective amount of the chlorine dioxide solution is admixed with the 1 Printed from Mimosa 09 37 10 PC1/US9S/02128 process water The chlorine dioxide solution is present in the process water in an amount sufficient to treat contaminants on the object and in the process water The oxidation reduction potential of the process water is monitored When the 5 oxidation reduction potential of the process water falls below a predetermined level, the steps of generating, admixing, and monitoring are repeated until substantially all of the contaminants in the process water and on the objects have been treated ma preferred form of the invention, the method includes generating the chlorine dioxide solution by the reaction of a solution comprising sodium chlorite with a solution comprising phosphoric acid In another form of the invention, the chlorine dioxide solution may be generated by the reaction of 15 a solution comprising sodium chlorite and sodium chloride with a solution comprising phosphoric acid Alternatively, the chlorine dioxide solution may be generated by the reaction of a solution comprising sodium chlorite with a solution comprising phosphoric acid and sodium 2-ethylhexyl sulfate 20 In yet another form of the invention, the chlorine dioxide solution may be generated by the reaction of a solution comprising sodium chlorite and sodium chloride with a solution comprising phosphouc acid and sodium 2-ethylhexyl sulfate The method may further include monitoring the pH of the 25 process water admixed with the chlorine dioxide solution Additionally, the method may include maintaining of the pH of the process water admixed with the chlorine dioxide solution below about 11 In a more preferred form of the invention, the method includes maintaining the pH of the process water admixed 3 0 with the chlorine dioxide solution between about 2 and about 10 5 The present invention also provides a method for treating fresh produce to remove debris and inhibit the growth of fungus The method comprises submerging the produce in process 35 water The process water comprises an affective amount of a chlorine dioxide solution The chlorine dioxide solution is present in the process water in an amount sufficient to clean 2 Printed from Mimosa 09 37 10 PCT/US9&02128 substantially all debris from the surface of the produce and to inhibit the growth of fungus on the produce In a preferred form of the invention, the effective amount of chlorine dioxide solution in the process water is at least about 0 l ppm. In 5 an even more preferred form of the invention, the effective amount of chlorine dioxide solution m the process water is between about 0 1 ppm and about 10 ppm In an even more preferred form of the invention, the effective amount of chlorine dioxide solution in the process water is between about 10 0 5 ppm and about 1 ppn; The method of the present invention may also include providing process water comprising chlorine dioxide solution that has a pH of less than 11 In a more preferred form of the invention, the process water comprising the chlorine dioxide 15 solution has a pH of between about 2 and about 10 5 In an even more preferred form of the invention, the pH of the process water comprising the chlorine dioxide solution is between about 3 and 10 It is also preferred that the produce is submerged in the process water comprising the chlorine 20 dioxide solution for at least about thirty seconds The method may further comprise generating the chlorine dioxide solution in the process water by the reaction of a solution comprising sodium chlorite with a solution comprising phosphoric acid Alternatively, the chlorine dioxide solution 25 in the process water may be generated by the reaction of a solution comprising sodium chlorite and sodium chloride with a solution comprising phosphoric acid In yet another form of the invention, the chlorine dioxide solution in the process water may be generated by the reaction of a solution comprising 30 sodium chlorite and sodium chloride with a solution comprising sodium 2-ethylhexyl sulfate and phosphoric acid Additionally, the method may include passing the produce under a flow of a second chlorine dioxide solution to wash debris from the produce The second chlorine dioxide solution 35 may be generated by the reaction of a solution comprising sodium chlorite with a solution comprising phosphoric acid, sodium 2-ethylhexyl sulfate, and either dodeeylbenzenesulfomc 3 Printed from Mimosa 09 37 10 WO 960MW9 PCTAJS9M>2128 acid or sodium dodecylbenzene sulfonate Alternatively, the second chlorine dioxide solution may be generated by the reaction of a solution comprising sodium chlorite and sodium chloride with a solution comprising phosphoric acid, sodium 5 2-ethylhexyl sulfate, and either dodecylbenzenesulfonic acid or sodium dodecylbenzene sulfonate Additionally, the present invention provides a method for treating process water The method comprises providing process water having at least one contaminant from the following group 10 debris, soil, fungus, and organic chemicals An effective amount of a chlorine dioxide solution is admixed with said process water to treat the process water by oxidizing contaminants in the process water The method includes providing a monitor for sensing the oxidation reduction 15 potential of the process water, positioning m the process water the monitor for sensing the oxidation reduction potential residual of the process water, and monitoring the oxidation reduction potential residual of the process water Additional amounts of the chlorine dioxide solution are generated when the 20 oxidation reduction potential residual drops below a predetermined level and the additional amounts of the chlorine dioxide solution are admixed with said process water to continue to treat contaminants in the process water The method may further include generating the chlorine 25 dioxide solution by the reaction of solution comprising sodium chlorite with a solution comprising phosphoric acid Alternatively, the method may include generating the chlorine dioxide solution by the reaction of solution comprising sodium chlorite and sodium chloride with a solution comprising 3 0 phosphoric acid or phosphoric acid and sodium 2-ethylhexyl sulfate In another form of the invention, the method includes generating the chlorine dioxide solution by the reaction of a solution comprising sodium chlorite and sodium chloride with a solution comprising phosphoric acid and solium 2-ethylhexyl 3 5 sulfate The method may include monitoring the pH of the process water admixed with the chlorine dioxide solution and 4 Printed from Mimosa OS 37 10 PCI7US9S/02I28 maintaining the pH of the process water admixed with the chlorine dioxide solution below about 11 In a more preferred form of the invention, the pH is maintained between about 2 and about 10.5 These and other advantages and features will become apparent from the detailed description of the best mode for carrying out the invention that follows Brief Description of the Drawings In the drawings, like element designations refer to like parts throughout the several views, and- Fig 1 is schematic view of produce cleaning assembly line used in the method of the present invention, Fig 2 is a fragmentary schematic view of the chlorine 15 dioxide generator and controller shown in Fig 1, and Fig 3 is a fragmentary schematic view of another chlorine dioxide generator and controller shown m Fig 1.

Best Mods for Carrying out the Invention Referring to Figs. 1 and 2, a produce washing assembly line is shown The assembly line 10 includes a dump tank 12 and a bin conveyor 14 which has an entrance side 16, a tank portion 18, and an exit side 20. A process water control loop 22 extends off of the dump tank 12. The process water control 2^ loop 22 has an inlet 24 from the dump tank 12 into the loop 22 and an outlet 26 from the loop 22 into the dump tank 12 A filter 28 is positioned on the inlet 24 of the control loop 22 Process water from the dump tank 12 is pumped through the loop 22 so that the composition of the process water can be 30 monitored and maintained A process water controller 30 and a chlorine dioxide reactor 32 are attached to the control loop 22. The process water controller 3 0 includes an Oxidation Reduction Potential (ORP) probe 34 which senses the ORP residual in the process 35 water passing through the control loop 22. The controller 30 also includes a flov indicator 36 whuch indicates to the controller 30 that process water is flowing through the loop Printed from Mimosa 09 37 10 PCT/DS9S/02128 22 When the flow indicator 35 indicates that process water is flowing through the loop 22, the controller 3 0 enables the ORP probe 34 to measure the ORP residual in the process water. If the ORP probe 34 indicates that the ORP residual in the 5 process water is too low, the controller 3 0 activates the chlorine dioxide reactor 32 to generate chlorine dioxide solution A pH probe 38 monitors the pH of the process water. Storage tanks 40, 42 of pH adjusting agents are attached to 10 pumps 44, 46 whicn are controlled by controller 30. Storage tank 4 0 stores a pH reducing agent Storage tank 42 stores a pH boosting agent The controller 3 0 is operable for feeding pH adjusting agents into the process water The controller 3 0 controls a first pump 48 and a second 15 pump 50 which are attached to a first storage tank 52 and a second storage tank 54, respectively. The pumps 48, 50 aie operable for pumping solutions from the storage tanks 52, 54 to the reactor 32 The controller 3 0 activates pumping o" proportional amounts of solutions from each of the tanks 52, 20 54 An apple conveyor 56 extends into the dump tank 12 The apple conveyor 56 is operable for moving apples out of the dump tank 12 and through a series of stations before the apples are sorted, sized and packed. The firBt station along the apple 25 conveyor 5 6 includes a plurality of rotating brushes 58 and a spray bar 60. The spray bar 60 is operable for emitting a flow of a second r hlorme dioxide solution 62 onto apples The chlorine dioxide solution 62 is monitored and produced by a chlorine dioxide generation system 64, shown in more detail in 30 Fig 3.

The chlorine dioxide generation system 64 includes an inlet 66 which is operable for feeding potable water through conduit 6 8 past flow meter 70 The flow meter 70 is operable for transmitting flow rate information to controller 72 35 Controller 72 is operable for signalling a first pump 74 to pump a solution from a first storage tank 76 and a second pump 78 to pump a solution from a second storage tank 80 The first 6 Printed from Mimosa 09 37 10 PCT/US9S/021M and second pumps 74, 78 are operable for pumping solutions to reactor 82 through feed lines 84 and 86 The chlorine dioxide solution from the reactor 82 are fed through line 8 8 and into conduit 68 which feeds into the spray bar 60.

Further down the apple conveyor 56 from the spray bar 60 is a rinsing sprayer 90 The rinsing sprayer 90 is operable for rinsing apples with potable water The next station along the apple conveyor 56 is a drying station 92. The drying station 92 includes a fan 94 for blowing ambient temperature 10 air over apples on the conveyor 56 Following the drying station 92 is a waxing station 96 which includes a plurality of rotating brushes 98 and an overhead spraying mechanisms 100 which are operab3e for spraying wax on the surface of apples After the waxing station 96 is a final drying station 102 which 15 includes a fan 104 which is operable for blowing heated air on apples on the conveyor 56 In a preferred form of the invention, the produce washing assembly line 10 is operated m the following manner The dump tank 12 is filled with approximately 3,000 gallons of process 20 water 106 The process water 106 is monitored by pumping the process water 106 through the control loop 22 As process water 106 enters the inlet 24 of the control loop 22, the process water 106 passes through the filter 28 The filter ^8 separates particulate matter, such as leaves, twigs, and other 25 orchard debris, from the process water 106 In a preferred form of the invention, the control loop 22 includes a differential switch (not shown) installed on the filter 28 for measuring the accumulation of particulate matter on the filter 2b When a predetermined level of particulate matter has 30 accumulated on the filter 28, the differential switch activates an automatic backwash (not shown) which washes the particulate matter out of the system through conduit 108.

The process water 106 is admixed with between about 0 1 and about 10 ppm chlorine dioxide solution from the reactor 32 35 In a more preferred form of the invention, the process water 106 is admixed with between about 0.5 and about 1 0 ppm chlorine dioxide solution In an even more preferred form of Printed from Mimosa 09 37 10 the invention, the process water 106 is admixed with about 1 0 ppm chlorine dioxide solution Preferably, the process water 106 admixed with the chlorine dioxide solution has a pH of less than 11, and in a more 5 preferred form of the invention, a pH of between about 2 and about 10.5, and more commonly, between about 3 and about 10 If the apples being cleaned m the assembly line 10 are heavily scaled, l e covered in hard water deposits, the pH of the process water 106 admixed with tne chlorine dioxide solution 10 is maintained well below 7, and preferably at about 3 If the apples are not scaled, but instead are covered mainly in debris, such as orchard soil, the pH of the process water 106 admixed with the chlorine dioxide solution is maintained at between about 7 and about 10 Accordingly, the preferred pH 15 of the process water 106 admixed with the chlorine dioxide solution depends on the type of debris present on the apples 114 and m the process water 106.

The chlorine dioxide solution is generated by reacting one part of a First Solution fed by the first pump 48 from tank 52 20 with between one and five parts of a Second Solution fed by the second pump 50 from tank 54 In a preferred form of the invention, one part of the First Solution is reacted with two parts of the Second Solution The First Solution comprises an active ingredient of sodium chlorite In a more preferred form 25 of the invention, the First Solution comprises 9 4% of 80% technical sodium chlorite and the balance water In another form of the invention, the First Solution comprises 9 4% of 80% technical sodium chlorite, 15% sodium chloride and the balance water.

The Second Solution comprises phosphoric acid as an active ingredient It is preferable to include an anionic surfactant and coupling agent, such as sodium 2-ethylhexyl sulfate m the Second Solution In a more preferred form of the invention, the Second Solution comprises 1% sodium 2-ethylhexyl sulfate, 35 7.5% phosphoric acid and the balance water The First, Solution and the Second Solution are fed into the reactor 32 by pumps 48, 50 In the reactor 32, the First 6 Printed from Mimosa 09 37 10 PCT/DS95702128 Solution and Second Solution are allowed a contact time of at least about 15 minutes When the controller 3 0 determines that more chlorine dioxide solution is needed in the process water 106 due to the reading of the ORP probe 34, the controller 30 5 activates the pumps 48, 50 to feed more of the First and Second Solution to the reactor 32 As the First and Second Solutions enter the reactor 32, the chlorine diorcide solution in the reactor 32 is displaced from the reactor 32 into conduit 110 which empties into the loop 22 and into the dump tan*. 12 10 Substantial foaming of the chlorine daoxide solution is undesirable since foam could be detrimental to the pumps 48, 50 on the control loop 22. Accordingly, it is preferred that the First Solution and the Second Solution include surfactants which produce little to no foam 15 The controller 30 monitors and controls the composition of the process water 106 in the following manner The desired ORP level is set on the controller 3 0 The ORP level is indicative of a particular chlorine dioxide residual in the process water 106 The pH of the process water 106 is monitored by the pH 20 probe 38 As process water 106 flows through loop 22, the pH probe 3 8 monitors the pH of the process water 106 If the pH m the process water 106 is too high, the second pump 50 is activated to pump a higher proportion of the Second Solution from storage 25 tank 54 to the reactor 32 Generally, the second pump 50 is manually calibrated to pump a higher proportion of the Second Solution for pH control, although it is foreseeable that this calibration of the second pump 50 could be automated The amount of the Second Solution can be increased until the 5 30 parts of the Second Solution are being fed for each 1 part of the First Solution. Generally, it is undesirable to feed the Second Solution at a race higher than 5 parts for each 1 part of First Solution since proper reactions may not take place in the reactor 32 If a lower pH is desired, an effective amount of a pH reducing agent may be added to the process water 106 The controller 3 0 activates pump 44 to pump pH reducing agent from 9 Printed from Mimosa 09 37 10 PCTA3S95/02128 storage tank 4 0 to feed through conduit 110 and into the process water 106. In a preferred form of the invention, the pH reducing agent comprises phosphoric acid as an active agent Sodium 2-eihylhexyl sulfate may be present in the pH reducing 5 agent to provide an increase m surface activity In a more preferred form of the invention, the pH reducing agent comprises 26 25% phospfeoij-c acid, 1 4% sodium 2-ethylhexyl sulfate and the balance water.

If the pH of the process water 106 is too low, the 10 controller 3 0 activates pump 46 to pump pH boosting agent from storage tank 42 into feed to the process water 106 Preferably, the pF boosting agent comprises sodium hydroxide A chelant, such as srvjium gluconate, may be part of the boosting agent to aid in cleaning mineral type debris. In a 15 more preferred form of the invention, the pH boosting agent comprises 42.5% sodium hydroxide, 17 5% spdium gluconate, and the balance wat ar Bins 11? 1 i eshly-harvested apples 114 are placed on the entrance side 16 of the bin conveyor 14 The apples 114 may 20 have contaminants such as debris, orchard soil, fungus, organic chemicals such as agricultural chemicals, and hard water scale on their surfaces As tne bins 112 move into the tank portion 18 of the conveyor 14, the bins 112 become submerged in process water 106 in the dump tank 12. The apples 114 float out of the 25 bins 112 into the process water 106 in the dump tank 12 While the apples 114 are m the dump tank 12, the apples 114 are cleaned, descaled, and sanitized by contact with the process water 106 which has admixed with it the chlorine dioxide solution. As the apples 114 float toward the surface o£ the 30 dump tank 12, a water current (not shown) pushes the apples 114 toward the apple conveyor 56 Preferably, the apples 114 remain in the dump tank 12 for at least 30 seconds before being pushed onto the conveyor 56 An estimated 75-fl5% of the cleaning, descaling, and sanitizing of the apples 114 is 35 accomplished by the process water 106 comprising the chlorine dioxide solution in the dump tank 12 Printed from Mimosa 09 3710 Along with the apples 114 being cleaned, descaled and sanitized by the process water 106 m the dump tank 12, the bins 112 are cleaned and sanitized As the apples 114 float to the surface of the dump tank 12, the bins 112 continue along 5 the bin conveyor 14 and out the exit side 20 of the conveyor 14 for re-use.

An additional benefit of the present invention is the treatment of the process water 106 Just as the chlorine dioxide solution treats the apples 114 and the bins 112, 10 organic chemicals and contaminants m the process water 106 are treated by the chlorine dioxide solution Without the use of the chlorine dioxide solution in the process water in the dump tank, the process water became brown, had an unpleasant odor, and was full of sludge after apples had been washed m the 15 system for a few days With the addition of the chlorine dioxide solution to the process water 106, the process water 106 remains clear and odorless, even after weeks of treating apples in the system As che apples 114 proceed down the apple conveyor 56, the 20 apples 114 roll on top of the rotating brushes 58 and pass underneath the spray bar 60. The spray bar 60 emits a second chlorine dioxide solution 62 onto the apples 114 The second chlorine dioxide solution 62 is generated by the generation system 64 illustrated m Pig 3 The generation system 64 is 25 operated by feeding potable water through the inlet 65 of conduit 68 The flow of potable water is monitored by flow meter 70 The readings from flow meter 70 are transmitted to controller 72 The controller 72 signals pumps 74, 78 to pump solutions from storage tanks 76, 80 The solutions are fed to 3 0 the reactor 82 and then into the potable water in conduit 68 to create the ch1orine dioxide solution 62 Storage tank 76 stores the First Solution, as described above Storage tank 80 stores a Third Solution.

The controller 72 activates pumps 74, 78 to pump First 35 Solution and Thud Solution from tanks 76, 80, respectively, through feed lines 84, 86 and into the reactor 82 As the solutions enter the reactor 82, previously generated product 11 Printed from Mimosa 09 37 10 is expelled from the reactor 82 into line 88 and then •• nto conduit 68 where it mixes with the water to form the second chlorine dioxide solution 62 Preferably the solutions are allowed a contact time of at least about 15 minutes in the 5 reactor 82.

The Third Solution comprises an anionic surfactant, such as dodecylbenzenesulfomc acid or sodium dodecylbenzene sulfonate, and an anionic surfactant coupling agent, such as sodium 2-ethylhexyl sulfate. In a preferred form of the 10 invention, the Third Solution can be m the form of 1 6V sodium 2-ethylhexyl sulfate, 4% dodecylbenzenesulfonic acid, 7 5% phosphoric acid, and the balance water In another form of the invention, the Third Solution comprises 3% sodium 2-ethylhexyl sulfate, 7 5% dodecylbenzenesulfonic acid, 15% phosphoric acid, 15 and the balance water The sodium 2-ethylhexyl sulfate provides stabilizing properties in the second chlorine dioxide solution 62 so that the solution 62 will feed through the spray bar 60 without substantial clogging The controller 72 controls flow rates of the First Solution 2 0 and Third Solution to the reactor 82 such that the second chlorine dioxide solution 62 has a chlorine dioxide residual of between about 0 1 ppm and about 10 ppm It is preferred that the second chlorine dioxide residual in the solution 62 is between about 1 and about 5 ppm Although, the solution 62 25 is generally very effective at about 1 0 ppm In a preferred form of the invention, the chlorine dioxide solution 62 is generated by reacting one part of the First Solution, as described above, with between one and five parts of the Third Solution In an even more preferred form of the 3 0 invention, one part of the First Solution is reacted with 5 parts of the Third Solution.

The pH of the second chlorine dioxide solution 62 is monitored Preferably, the pH of the solution 62 is between about 3 and about 7 In a more preferred form of the 3 5 invention, the pH of the solution 62 is maintained at about 3 If the pH of the solution 62 is too high, more of the Third Solution is fed to the reactor 82 To adjust the pH, the feed 12 Printed from Mimosa 09 3710 rate of the Third Solutaon can be increased to 5 parts for each 3 part of the First Solution. Generally, it is undesirable to feed the Third Solution at rates higher than 5 parts for each one part of the First Solution, since undesired reactions may 5 take place in the reactor 82.

The second chlorine dioxide solution 62 emitted by the spray bar 6 0 completes, cleaning, descaling, and sanitizing of the apples 114 The dodecylbenzenesulfonic acid or sodium dodecylbenzene sulfonate in the Third Solution which is fed to 10 the chlorine dioxide reactor 82 produces a slight bubbling of the solution 62 from the spray bar 60 which is helpful for indicating to an observer that a chlorine dioxide is present in solution 62 As the apples 114 pass over the rotating brushes 58, the apples 114 are tumbled by the brushes 58 so 15 that chlorine dioxide solution 62 is emitted from the spray bar 60 onto all surfaces of the apples 114 Further, the fractional action of the brushes 58 on the apples 114 provides a mechanical agitation of the apples 114 which gently wipes debris and residue from the surface of the apples 114 After 20 passing over the apples 114, the second chlorine dioxide solution 62 may pass to a drain (not shown) or be added to the process water 106 m the dump tank 12.

As the apples 114 continue on the apple conveyor 56, the apples 114 pass under the rinsing sprayer 90 which emits 25 potable water onto the apples 114 to remove residual amounts of chlorine dioxide solution 62 from the surface of the apples 114 After the rinsing sprayer 90, the apples 114 enter drying station 92 where a fan 94 blows ambient temperature air over the surface of the apples 114. The apples 114 are dried 30 sufficiently m the drying station 92 so that wax will adhere to the surfaces of the apples 114 during the next phase of processing.

After the apples 114 have been dried, the apples 114 continue on the apple conveyor 56 to the waxing station 96 35 As the apples 114 pass through the waxing station 96, the apples 114 are tumbled on rotating brushes 98 as an overhead spraying mechanisms 100 sprays wax onto the apples 114 The 13 Printed from Mimosa 09 37 10 rotating brushes 98 spread the wax across the surface of the apples 114 After the waxing station 96, the apples 114 are moved into the final drying station 102 where heated air is blown across the surface of the apples 114 by fan 104 to 5 completely dry the apples 114 After the apples 114 exit the final drying station 102, the apples 114 proceed to sorting and sizing stations (not shown) for final packing This invention provides a simple and effective method for cleaning, sanitizing, and descaling produce after harvest The 10 method of the present invention would be useful on many types of produce, such as pears, peaches, plums, apricots, oranges, grapefruit, lemons, limes, avocados, cantaloupe, honeydew, watermelon, zucchini, squash, carrots, potatoes, and cucumbers In addition, the present invention provides a simple and 15 effective method for cleaning and sanitizing of contaminated water or other contaminated objects submerged m water, such as apple bins In addition, the present invention provides a safe and effective method for the use of a chlorine dioxide solution by 20 allowing for on site generation According to the present invention, small amounts of chlorine dioxide solutions, including solutions with up to 50% active chlorine dioxide, can be generated on site as needed Accordingly, the present invention provides environmental and safety benefits by 25 eliminating the need for the shipment, storage, and handling of hazardous chlorine dioxide solutions The nature and substance of the instant invention as well as its objects and advantages will be more clearly understood by referring to the following specific examples Example 1 Apples were rolled in moist orchard soil until they were covered with soil Then, the apples were allowed to dry Once dry, the apples were allowed to soak in a 5 ppm solution of 35 chlorine dioxide produced trom a reaction of one part of First Solution with one part of Second Solution No direct brush action was applied After on-j minute, an apple was removed 14 Printed from Mimosa 09 37 10 from the chlorine dioxide solution Baaed upon visual inspection of the apple, approximately 95% of the soil had been removed from the surface of the apple After 30 minutes, another apple was removed from the chlorine dioxide solution 5 Based upon visual inspection of the apple, approximately 98% of the soil had been removed from the surface of the apple Example 2 Three identical containers were obtained Container #l was 10 filled with a chlorine dioxide solution having a concentration of chlorine dioxide at 5 ppm The solution was obtained from a reaction of one part of First Solution with one part of Second Solution Container #2 was filled with a chlorine dioxide solution having a chlorine dioxide concentration of 11 15 ppm. The solution was obtained from a reaction of one part of First Solution w: th one part of Second Solution Container #3 was filled with deionized water Mold was introduced into each of the containers A first sample was taken from each of the three containers after five minutes. A second sample was taken 20 from each of the three containers after 50 minutes All samples were placed onto prepared mold growth media and allowed to incubate for three days At the end of three days, the mold plates were observed For the samples taken from the 5 ppm and 11 ppm chlorine dioxide solutions, the samples showed negative 25 for mold growth For the samples taken from the solution which contained no chlorine dioxide, the sample showed positive for mold growth.

Sxanple 3 3 0 Two identical one liter volumetric flasks were obtained Flask #1 was filled with deionized water and Flask #2 was filled with an 8 ppm chlorine dioxide solution The chlorine dioxide solution was obtained from a reaction of one part of First Solution with one part of Second Solution Both flasks 35 were spiked with precisely the same amount of o-phenylphenol When ter"ed, 7 ppm residual of o-phenylphenol was present in Flask #1 Flask #2 showed a mild visual reaction upon addition Printed from Mimosa 09 37 10 FCT/US95/D2128 of the o-phenylphenol When tested, 1 ppm residual of 0-phenylphenol was present m Flask #2 Exaarpla 4 Two identical one liter volumetric flasks were obtained Flask #1 was filled with deionized water and Flask #2 was filled with an 8 ppm chlorine dioxide solution The chlorine dioxide solution was obtained from a reaction of one part of First Solution with one part of Second Solution Both flasks 10 were spiked with precisely the same amount of 1-hydroxyethvlidene-l, 1 -diphosphomc acid (HEDPA) When tested, 6 ppm residual of HEDPA was present in Flask #1 Flask #2 showed a mild visual reaction upon addition of the HEDPA When tested, Flask #2 indicated that no HEDPA residual was present Example 5 Two identical one liter volumetric flasks were obtained Flask #1 was filled with deionized water and Flask #2 was filled with 20 an 8 ppm chlorine dioxide solution The chlorine dioxide solution was obtained from a reaction of one part of First Solution with one part of Second Solution Both flasks were spiked with precisely the same amount of chlorophenol red (an organic dye) Flask #1 tested for positive for approximately 25 6 ppm chlorophenol red Residual was determined visually by the presence of a reddish color Flask #2 tested for virtually no chlorophenol red as determined by Flask #2 being absolutely colorless upon visual inspection While specific embodiments of the present invention have 3 0 been shown and described in detail to illustrate the utilization of the inventive principles, it is to be understood that such showing and description have been offered only be way of example, and not by way of limitation Protection by Letters Patent of this invention m all its aspects are set 35 forth in the appended claims and is sought to the broadest extent that the prior art allows 16 Printed from Mimosa 09 3710

Claims (7)

1. 282204

   WHAT IS CLAIMED IS

   1 A method of treating process water and produce submerged in said process water, said process water and said produce including at least one contaminant from the group consisting of debris, soil, fungus and/or organic chemicals, said method comprising providing a tank,

   introducing said process water into said tank,

   introducing s>aid produce into said tank and into said process water in said tank, generating a chlonne dioxide solution on site,

   admixing said chlonne dioxide solution into said process water, so that said chlonne dioxide solution will treat contaminants on said produce and m said process water,

   dunng treatment, removing process water from said tank and directing it through a control loop and then back to said tank,

   monitonng the oxidation reduction potential of said process water b> testing the process water that is m said control loop, and when said oxidation reduction potential of said process water is below a predetermined level, generating additional chlonne dioxide solution and admixing it with said process water and continuing this procedure until substantially all of said contaminants in said process water and on said produce have been treated
2. 2 The method of claim 1 further compnsmg generating said chlonne dioxide solution by the reaction of solution compnsmg sodium chlonte with a solution compnsmg phosphonc acid

   I MrELLhl/iijM*. i iui uhl r GrriGc OF N Z;17;12 MAR 1999;Received;282204;
3. 3 The method of claim 1 further composing generating said chlonne dioxide solution by the reaction of solution compnsmg sodium chlonte and sodium chlonde with a solution compnsmg phosphonc acid;
4. 4 The method of claim 1 further compnsmg generating said chlonne dioxide solution by the reaction of a solution compnsmg sodium chlonte with a solution compnsmg phosphonc acid and sodium 2-etlhylhexyl sulfate;
5. 5 The method of claim 1 further compnsmg generating said chlonne dioxide solution by the reaction of a solution compnsmg sodium chlonte and sodium chlonde with a solution compnsmg phosphonc acid and sodium 2-ethylhexyl sulfate;
6. 6 The method of claim 1 further compnsmg monitonng the pH of the process water admixed with the chlonne dioxide solution and maintaining the pH of the process water admixed with the chlonne dioxide solution below about 11;7
7. 7. The method of claim 6 further compnsmg maintaining the pH of the process water admixed with the chlonne dioxide solution between about 2 and about 105;8 The method of claim 1 composing admixing the additional chlonne dioxide solution into the process water as it flows through the control loop;9 The method of claim 1, further compnsmg removing the treated produce from the tank onto a conveyor and using the conveyor to;18;Gsuchi ';12 MAR 1999;RECEIVED;282204;from the tank, and dunng movement spraying a second chlonne dioxide solution onto the produce;The method ot claim 1, comprising removing the treated produce from the tank onto a conveyor and using tf e conveyor for moving the produce away from the tank, and providing the conveyor with rotating brushes, and rotating said brushes while they are in contact with the produce, so that the brushes will brush the produce and mechanically remove debns and residue from the produce;The method of claim 10, compnsmg spraying additional chlonne dioxide solution on the produce while the produce is on the conveyor and bemg moved by the conveyor away from the tank;The method of claim 1, compnsmg providing a chlonne dioxide generator, and storage containers of components that when mixed react and produce a chlonne dioxide solution, and a pump for each such component, located between the storage container for the component and the chlonne dioxide generator, and a controller for the pumps, and an oxidat.on reduction potential probe in the process water passing through the control loop, and using such probe to measure the oxidation reduction potential of *he process water, and using the controller to turn on the pumps and pump the components from their containers to the chlonne dioxide generator in response to the oxidation reduction potential of the process water being too low, so that the components will be pumped to the chlonne dioxide generator and additional chlonne dioxide solution will be generated, and delivenng said additional chlonne dioxide solution from the generator to the process water iMFELLt'uTuH^ I r lUr'uH I ^ GrMut.

   OFNZ

   12 MAR 1999

   REC EIV E D

   19

   282204

   13 The method of claim 12, further compnsmg removing the treated produce from the tank onto a conveyor and using the conveyor to move such produce away from the tank, and dunng movement spraying the second chlonne dioxide solution onto the produce

   14 The method of claim 12, compnsmg moving the treated produce from the tank onto a conveyor and usmg the conveyor for moving the produce away from the tank, and providing the conveyor with rotating brushes, and rotating said brushes while they are in contact with the produce, so that the brushes will brush the produce and mechanically remove debns and residue from the produce

   15 The method of claim 14, compnsmg spraying additional chlonne dioxide solution on the produce while the produce is on the conveyor and bemg moved by the conveyor away from the tank

   16 The method of claim 1, wherein the produce is apples

   17 The method claim 16, further comprising removing the treated apples from the tank onto a conveyor and usmg the conveyor to move such apples away from the tank, and dunng movement spraying a second chlonne dioxide solution onto the apples

   18 The method of claim 16, compnsmg removing the treated apples from the tank onto a conveyor and usmg the conveyor for moving the apples away from the tank, and providing the conveyor with rotating brushes, and rotating said brushes while they are m contact with the apples, so that the brushes will brush the apples and mechanically remove debns and residue from the apples

   20

   intellectual r nuPeni i di-fice OF N Z

   1 2 MAR 1999

   RECEIVED

   282204

   19 The method of claim 18, compnsmg spraying additional chlonne dioxide solution on the apples while the apples are on the conveyor and being moved by the conveyor away from the tank

   20 A method of treating process water and produce submerged in said process water, said process water and said produce including at least one contaminant from the group consistmg of debns, soil, fungus and/or organic chsmicals, said method compnsmg,

   providing a tank,

   introducing said process water into said tank,

   introducing said produce into said tank and into said process water in said tank, providing on site a chlorine dioxide generator and storage containers of components that when mixed react and produce a chlonne dioxide solution, and a pump for each component, located between the storage container for the component and the chlonne dioxide generator, and a controller for the pumps, and an oxide reduction potential probe m the process water,

   usmg the chlonne dioxide generator to generate on site a chlonne dioxide solution and deliver it mto the process water,

   using the oxidation reduction potential probe to measure the oxidation reduction potential of the process water, and using the controller to turn on the pumps and pump the components from their containers to the chlonne dioxide generator in response to the oxidation reduction potential of the process water being too low, so that the components will be pumped to the chlonne dioxide generator and additional chlonne dioxide solution will be generated, and delivenng the additional chlonne dioxide solution from the generator to the

   INTELLtCKiML t-Mui cm l urFlu OF fa Z

   process water

   21

   12 MAR 1999

   RECEIVED

   282204

   21 The method of claim 20, further comprising removing the treated produce from the tank onto a conveyor and usmg the conveyor to move such produce away from the tank, and dunng movement spraying a second chlonne dioxide solution onto the produce

   22 The method of claim 20, compnsmg removing the treated produce from the tank onto a conveyor and usmg the conveyor for moving the produce away from the tank, and providing the conveyor with rotating brushes, and rotating said brushes while they are m contact with the produce, so that the brushes will brush the produce and mechanically remove debns and residue from the produce

   23 The method of claim 20, compnsmg spraying additional chlonne dioxide solution on the produce while the produce is on the conveyor and being moved by the conveyor away from the tank

   24 The method of claim 20, wherem the produce is apples

   25 he method of claim 24, further compnsmg removing the treated apples from the tank onto a conveyor and using the conveyor to move such apples away from the tank, and dunng movement spraying a second chlonne dioxide solution onto the apple

   26 The method of claim 24, compnsmg removing the treated apples from the tank onto a conveyor and using the conveyor for moving the apples away from the tank, and providing the conveyor with rotating brushes, and rotating said brushes while they are in contact with the apples, so that the brushes will brush the apples and mechanically remove debns and residue:

   22

   -Ltli I Uml i-riurtnlY OFFICE OF NZ

   12 MAR 1999

   RECEIVED

   282? 0

   27 The method of claim 26, comprising spraying additional chlonne dioxide solution on the apples while the apples are on the conveyor and bemg moved by the conveyor away from the tank

   28 The method of claim 27, further compnsmg removing the treated apples from the tank onto a conveyor and usmg the conveyor to move such apples away from

   29 The method of claim 28, further compnsmg spraying a second chlonne dioxide solution onto the apples as the apples are bemg moved away from the tank by the conveyor

   30 The method of claim 28, compnsmg providing the conveyor with rotating brushes and rotating said brushes while they are in contact with the apples, so that the brushes will brush the apples and mechanically remove debns and residue from the apples

   31 The method of claim 30, compnsmg spraying additional chlonne dioxide solution on the apples while the apples are on the conveyor and being moved by the conveyor away from the tank

   32 The method of claim 24, compnsmg delivering the apples to the tank by placing the apples in containers and submerging the containers m the tank, so that the apples will float up out of the containers, and removing the containers from the tank when they are empty of apples the tank

   33 A method for treating fresh produce to remove inhibit the growth of fungus, compnsmg

   INTELLECTUAL fnyrtRlY OFFICE OF N Z

   12 MAR 1999

   23

   RECEIVED

   2822 0 A

   submerging produce in a bath of process water,

   generating on site a chlonne dioxide solution and admixing it to m said process water so as to clean debns from the surface of the produce and inhibit the growth of fungus on the produce, and removing the treated produce from the bath onto a conveyor and usmg the conveyor to move such produce away from the bath

   34 The method of claim 33, further compnsmg dunng use of the conveyor to move the produce away from the bath, spraying a second chlonne dioxide solution onto the produce

   35 he method of claim 33, compnsmg providing the conveyor with rotating brushes and rotatmg said brushes while they are m contact with the produce, so that the brushes will brush the produce and mechanically remove debns and residue from the produce

   36 The method of claim 35, compnsmg spraying additional chlonne dioxide solution on the produce while the produce is on the conveyor and is being moved by the conveyor away from the bath

   37 A method of treating process water and produce submerged in said process water, substantially as descnbed herein and with reference to any example or drawing

   INTELLECTUAL i-tvjrth i Y OFFICE OF l\i Z

   12 MAR 1999

   end of claims

   RECEIVED

   24