Continuous production system for plasma-activated water for disinfecting agricultural products

Abstract

This invention involves a continuous production system for plasma-activated water designed for safely and efficiently disinfecting agricultural products. The previously developed systems for producing plasma-activated water have been tested by applying plasma for a certain period of time in a fixed volume. While in this invention, a continuous flow of water is introduced into the system and under the influence of plasma, a continuous flow of plasma-activated water is produced. This advantage increases the scope of application of plasma-activated water in various fields. Additionally, using a plasma spray and irradiating it on the water surface is simple and convenient to use compared to other methods.

Description

Continuous Production System for Plasma-Activated Water for Disinfecting Agricultural Products

[0001] This invention involves a significant advancement in the field of agricultural disinfection. Unlike previous systems that utilized plasma for a limited period in a fixed volume, this innovative continuous production system introduces a steady stream of water into the process, resulting in a continuous flow of plasma-activated water. This method not only enhances the efficiency of disinfecting agricultural products but also expands the potential applications of plasma-activated water across various industries.

[0002] One of the key advantages of this system is the simplicity and convenience of using a plasma spray to irradiate the water surface. This method is not only effective but also user-friendly, making it a practical solution for farmers and agricultural professionals seeking to improve the safety and quality of their products. Furthermore, the continuous nature of the production process ensures a consistent supply of plasma-activated water, providing a reliable and sustainable solution for disinfection needs.

[0003] C02F 1 / 46 – H05H 1 / 00

[0004] KR1020230064972

[0005] PLASMA ACTIVATED WATER PRODUCTION DEVICE USING GLIDING ARC PLASMATRON

[0006] Disclosed is a plasma activated water production device using a gliding arc plasmatron, including: an air supply unit connected to an air discharge pipe; a plasma generator which has a plasma generation unit and generates radicals by causing air introduced through the air discharge pipe to flow through the plasma generation unit; and a reaction tank formed into a water tank for reacting radicals generated from the plasma generator with water. Accordingly, plasma activated water production efficiency is dramatically improved.

[0007] This mentioned patent also involves a system for producing plasma-activated water, similar to our claimed one. However, our solution differs from this patent in method and process of generating plasma and treating the water as well as structural aspects. Moreover, ours proposes a solution that focuses on a continuous production system.

[0008] KR1020200048779

[0009] PLASMA ACTIVATED WATER PRODUCTION APPARATUS

[0010] An object of the present invention is to provide a plasma activated water production apparatus capable of mass-producing plasma activated water, which comprises: a body; a dielectric tube disposed around the outside of the body; and an external electrode disposed on the outer periphery of the dielectric tube. The body and the external electrode are formed to extend along the same axis, and plasma activated gas is generated between the main body and the external electrode.

[0011] While the overall purpose of the above mentioned patent resembles our claimed one, the structure and method of the designs are entirely different. Furthermore, ours has a primary focus on the continuity of the production whereas this one does not.

[0012] KR1020230080787

[0013] METHOD FOR PRODUCING ACTIVATED WATER USING PLASMA

[0014] The present invention relates to a method for producing activated water using plasma, activated water using plasma produced by the method for producing activated water, a sterilizing composition containing the activated water as an active ingredient, a sterilizing method including a step of treating an object to sterilize with the composition, agricultural products, livestock products, food, medicine or feed treated with the sterilizing composition, and a plasma activated water production device.

[0015] This patent shares the overall function and purpose of our design as a production system for plasma activated water which can be used in disinfecting agricultural produce. While the two patents have a lot in common, the structural aspects and mechanisms of their processing methods are different. Moreover, this one does not address the continuous production aspect which is a key point in our invention.

[0016] KR102475982

[0017] PLASMA ACTIVATED WATER PRODUCTION DEVICE

[0018] The present invention provides a plasma activated water production device in which plasma is stably generated and maintained in a process of converting water into activated water by plasma treatment. The present invention includes: a discharge electrode positioned inside a dielectric tube; a conductive electrode installed at an end of the dielectric tube to deliver plasma of the discharge electrode; a counter electrode installed at a predetermined interval from the conductive electrode to generate plasma between the conductive electrode and the counter electrode; and an injector for injecting water to pass through the plasma generated between the conductive electrode and the counter electrode.

[0019] This mentioned invention bears a strong resemblance to ours in terms of overall objective which is to introduce a method for continuous production of plasma activated water. While the two patents share this aspect, other specifications such as structural design, components and ingredients as well as their processing methods are different. For instance, this one features electrodes and injectors and makes no mention of a gas chamber, whereas ours features a more accessible structure and utilizes argon.

[0020] IN202321027681

[0021] METHOD FOR THE PRODUCTION OF PLASMA ACTIVATED WATER

[0022] Method for the production of plasma activated water The present invention relates to the production of plasma activated water using a simple and efficient method utilizing few and easily available components. A plurality of power cards (5) are connected in parallel to supply the required power to the copper electrodes (3) which have a mesh of fine wires placed 2 mm above the 2-5 mm layer of water flowing through the water channel (4) made of insulating material having high dielectric strength.

[0023] This invention relates to the production of plasma activated water for agricultural use, and shares similarities with our design in comprising elements and processing steps. However, the above mentioned patent focuses on creating a solution for pesticide while ours has a wider scope and can be used in the medical field as well. Another distinction is that ours emphasizes the continuous aspect of production in the claimed system. Therefore, the two patents vary in their structural details and mechanisms used in water treatment.

[0024] Here, the dielectric barrier discharge (DBD) method was used to create plasma in a system with two electrodes connected to a high-voltage power supply. Tungsten electrodes were chosen for their high melting point to prevent melting and deposits on the liquid's surface. A dielectric layer was placed on each electrode to control the strength of the electric field generated. Various gases such as argon, nitrogen, and oxygen were used for plasma spraying.

[0025] A system was created to produce plasma-activated water, where water entered a treatment vessel and moved slowly to the top while being exposed to plasma radiation. Water was vortexed and treated with plasma as it moved upward in the vessel. Plasma-activated water continuously exited the system, and plasma radiation occurred at the water surface and a distance of five millimeters from the surface. Control valves were used to adjust the flow rate and gas mixtures to create continuous plasma-activated water flow.

[0026] Overall, the system allowed for controlled plasma treatment of water to create plasma-activated water continuously without interruption. By adjusting the flow rate and gas mixtures, stable plasma treatment could be achieved for various applications.

[0027] By 2050, the world population is expected to reach 10 billion, highlighting the need for new methods of food production and processing to meet the world’s growing nutritional needs. Given the risks associated with food production due to bacterial and fungal infections, one of the most important considerations is to provide safe and healthy food while maintaining quality.

[0028] With increasing awareness, people are more inclined to consume processed foods that contain fewer preservatives. New methods in the food preparation process, such as the use of non-thermal technologies, can have minimal negative effects on food quality. Currently, irradiation, high-pressure processing, UV radiation, and ozonation are used to increase the shelf life of foods. The use of electromagnetic waves and fields, pulsed electric fields, and ultrasonic waves are among the non-thermal technologies that are commonly used to improve the extraction and purification of elements from fruits and vegetables. Recently, the use of non-thermal plasma technology in food processing has received attention.

[0029] Plasma, also known as the “fourth state of matter”, contains ions, electrons, atoms, free radicals, molecules in excited states, and UV photons. Plasma is classified into two categories based on thermodynamic equilibrium: thermal (hot) or non-thermal (cold). In cold plasma, the plasma spray temperature does not exceed 60 degrees Celsius. Dielectric barrier discharge (DBD), plasma jet, and corona discharge are some of the sources of plasma generation for common applications in the food industry.

[0030] Plasma-treated liquid is widely used in medical and food processing applications due to its high efficiency with minimal operating costs. Recently, studies have been conducted on the use of plasma-activated water for insecticide control, antibiotic control, and bactericidal applications.

[0031] The use of plasma for disinfection of agricultural products has been widely limited due to the variable surfaces and heterogeneous shapes. Therefore, to solve this problem, the use of plasma-activated water is of interest.

[0032] Plasma-activated water is a clean technology that has been proven to control various microbes and disinfect food. Reactive oxygen species (ROS), including hydroperoxyl , singlet oxygen (1O2), peroxyl , ozone (O3), superoxide anion , alkoxyl , hydroxyl radical (●OH), hydrogen peroxide (H2O2), and carbonate radical anion are generated by the effect of plasma on water. When these species are dissolved in water, the product is called plasma-activated water. In addition to bacteria, microbes are also inactivated by the effect of plasma-activated water.

[0033] Plasma-activated water and its effect on microbial load control and disinfection of agricultural products have been studied in various ways. In all these studies, plasma-activated water produced in a fixed and static volume has been used. Given that the application of this technology requires continuous production of this product, in this invention, continuous flow production of plasma-activated water has been carried out.Solution of Problem

[0034] One of the most important challenges in the discussion of plasma-activated water production is its discontinuous production, so that in all the prior studies and inventions, water is in a fixed volume and container is placed under the effect of plasma and plasma-activated water is created.

[0035] The dielectric barrier discharge (DBD) method, number 5 inwas used to create plasma. Two electrodes connected to a high-voltage power supply (25 kV), number 1 inconstitute the atmospheric pressure cold plasma generation system. The electrodes used in this system are made of tungsten because the melting point of tungsten is 422.3 °C and when connected to high voltage, tungsten does not melt and deposits are not formed on the surface of the liquid. A dielectric was placed on each of these electrodes (5). The thickness of the dielectric layer is proportional to the strength of the field generated between the electrodes. In plasma spraying, various gases such as argon, nitrogen, oxygen and their combinations, numbers 2, 3 and 4 inare used.

[0036] In order to produce plasma-activated water, the system shown inwas created. In this system, for continuous production of plasma-activated water, water from source number (6) enters the treatment vessel from the bottom through a controlled channel (7) (a peristaltic pump can also be used instead of this valve) and then moves slowly from the bottom to the top in container number (8) and is affected by plasma radiation (5).

[0037] The flow of water from the bottom of the container until it reaches the surface of the channels (9) embedded in the treatment vessel (8) causes the water to be exposed to plasma. Due to the plasma jet radiation in the treatment vessel and the location of the outlet channels (9) relative to the plasma jet (12), a vortex state is created for the water, and during the upward movement in the vessel, the water is subjected to plasma treatment in addition to being vortexed.

[0038] As the water rises to the level of the outlet channels (9), the plasma-activated water continuously exits the system and enters the vessel (10) and exits through the channel (11). Plasma radiation is performed at the water surface and at a distance of five millimeters from the water surface (5) (this distance can be increased or decreased depending on the intensity of the radiation and the diameter of the vessel). Using a one-way valve (7) allows controlling the flow into the treatment tank (8) and will cause changes in the flow rate (a peristaltic pump can also be used instead of valve number (7).

[0039] The inlet and outlet flows are controlled and adjusted until the desired stable flow is reached, in such a way that the appropriate time for plasma treatment of the water occurs and there is no interruption in the continuity of the flow. By incorporating a gas flow inlet control valve (4), various gas mixtures (such as air, argon, and other gases) can be used to create plasma-activated water. The presence of control valves 7 and 11 allows the system to create a continuous flow of plasma-activated water.

[0040] To investigate the continuous creation of plasma-activated water, the physical and chemical parameters of the water used in this system have been investigated. For this purpose, some chemical and physical properties of the initial water (before entering the device) have been measured and the results are given in [Table 1]. These properties include oxidation-reduction potential, electrical conductivity and pH as follows.

[0041] The oxidation-reduction potential indicates the tendency of chemicals to oxidize. The oxidation-reduction potential is measured in volts or millivolts. The measurement of this index indicates its antimicrobial properties regardless of the quality of the water.

[0042] The oxidation-reduction potential is considered an important factor affecting microbial inactivation, which damages the cell membrane of microbes and their defense mechanism, meaning that the higher the oxidation-reduction potential of the solution, the greater its oxidizing properties and the greater its antimicrobial activity.

[0043] Electrical conductivity indicates the ability of the solution to transmit electric current. Electrical conductivity is usually expressed in microsiemens per centimeter. Electrical conductivity helps measure of the ability of water to facilitate the flow of electricity through it. The active species and ions produced during plasma treatment are readily dissolved in water, which significantly alters its electrical conductivity.

[0044] The formation of highly reactive oxygen and nitrogen species (ROS, RNS) during plasma activation of water leads to an increase in the electrical conductivity of water, and its increase has a direct effect on increasing the efficiency of microbial load control. PH indicates the concentration of hydrogen ions in a solution. The reactions that occur between the chemical species formed in plasma and water lead to the acidification of water. The higher the level of free radical activity in water, the more acidic its environment will be. In other words, a decrease in pH increases the disinfecting power of plasma-activated water.

[0045] An increase in electrical conductivity and a decrease in the oxidation potential of water and a decrease in its pH are signs of the creation of plasma-activated water. The data obtained for this system are given in [Table 2] and the bar graphs in,and, which clearly show the details behind antibacterial and disinfectant properties of the produced plasma-activated water which were tested with different variables.

[0046] To investigate the changes and comparison between the variables of the device, the system was set up using two gases, argon and air, and using urban tap water, distilled water and deionized water and changing the flow rate of the incoming water, the changes in its indicators were examined up to 30 minutes after leaving the device, and the results are given in Figures 2-4. The plasma-activated water produced by the system was applied to almonds contaminated with aflatoxin AFB1, Salmonella bacteria and Aspergillus flavus fungus, and the results of its effectiveness on the samples are given in [Pic. 1], [Pic. 2 and [Pic. 3]. The results show the antibacterial and disinfecting properties of the plasma-activated water produced by the invented system.Advantage Effects of the Invention

[0047] • Production of a continuous flow of plasma-activated water

[0048] • Improvement upon previous attempts

[0049] • Wide scope of application

[0050] • Convenient and accessible

[0051] • Simple processing method

[0052] • Cost-effective

[0053] Shows a general view of the designed apparatus.

[0054] Declares a logarithm of changes in the oxidation reduction potential.

[0055] Displays a logarithm of changes in the electrical conductivity.

[0056] Depicts the changes in pH levels in different water sources.

[0057] Shows a general view of the device made for the continuous production of plasma-activated water and the connection between its parts which are:

[0058] (1): Plasma generator

[0059] (2): Gas tank (argon, nitrogen, etc.)

[0060] (3): Air tank

[0061] (4): Gas volume ratio regulator

[0062] (5): DBD plasma set and plasma nozzle

[0063] (6): Inlet water source

[0064] (7): Flow inlet control valve (a peristaltic pump can also be used in this part)

[0065] (8): Treatment tank in which plasma-activated water transfer pipes are installed from the bottom of this container.

[0066] (9): Plasma-activated water transfer pipes are installed in the treatment container and the water rises to the upper surface of the pipes, pours into them and is transferred to the outlet container.

[0067] (10): Plasma-activated water collection container

[0068] (11): Flow outlet pipe from which the plasma-treated water is discharged.

[0069] (12): Top view of the plasma sprayer's position relative to the treatment container and the pipes embedded in It

[0070] Shows a logarithm of changes in oxidation-reduction potential in different water sources including tap water, distilled water and deionized water under conditions of using air, argon and a 50% ratio of air and argon at three water flow rates of 1.5, 0.5 and 1.5 ml / min.

[0071] Depicts a logarithm of changes in electrical conductivity in different water sources including tap water, distilled water and deionized water under conditions of using air, argon and a 50% ratio of air and argon at three water flow rates of 1.5, 0.5 and 1.5 ml / min.

[0072] Displays the changes of pH levels in different water sources including tap water, distilled water and deionized water under conditions of using air, argon and a 50% ratio of air and argon at three water flow rates of 1.5, 0.5 and 1.5 ml / min.Examples

[0073] This invention can be used in cases where the use of plasma-activated water is required. More specific examples include washing fruits, vegetables, etc., as well as disinfecting surfaces, fruits, nuts, etc., medical equipment.

[0074] In the development process of this system, many tests and observations were done on the water and its treatment with plasma at various stages:

[0075] [Table 1] This table shows the physical and chemical properties of water before entering the system.

[0076]

[0077] [Table 2] This figure shows the properties of water placed in the system at a flow rate of 0.5 ml / min. The data was measured immediately after the water left the system.

[0078]

[0079] The disinfectant and antibacterial properties of the produced water using the designed system were tested with three different samples:

[0080] [Pic. 1] Shows a graph of the effect of plasma-activated water on the percentage reduction of aflatoxin (AFB1) in almond samples with increasing plasma-activated water application time (in minutes)

[0081] [Pic. 1]

[0082]

[0083] [Pic. 2] Shows the effect of plasma-activated water on the reduction of Salmonella bacteria (in terms of logarithmic unit reduction) in almond samples with increasing plasma-activated water application time (in minutes)

[0084] [Pic. 2]

[0085]

[0086] [Pic. 3] Shows the effect of plasma-activated water on the reduction of Aspergillus flavus fungus (in terms of logarithmic unit reduction) in almond samples with increasing plasma-activated water application time (in minutes)

[0087] [Pic. 3]

[0088]

[0089] The developed plasma activated water production machine has applications in various industries including the agricultural and medical fields listed below:

[0090] Agricultural industries:

[0091] A: Used for washing and disinfecting fruits, vegetables, meat and seafood (fish, shrimp, etc.) and nuts (due to the ability of plasma activated water to eliminate and control bacteria, microorganisms and viruses)

[0092] B: Used to improve seed germination

[0093] Medical industries:

[0094] A: Used for washing and disinfecting medical and dental equipment

[0095] B: Used to disinfect surfaces

[0096] C: Used as mouthwash

[0097] D: Used to control and eliminate bacteria, viruses and microorganisms

Claims

A continuous production method and apparatus for plasma-activated water is developed which can be used in disinfecting agricultural products and medical equipment.According to claim 1, the system includes a processing device with the following components: a plasma generator, a gas tank, an air tank, a gas volume ratio regulator, a DBD plasma set and plasma nozzle, an inlet water source, a treatment tank, transfer pipes, control valves and a water collection container.According to claim 1, the claimed system uses cold plasma technology to continuously produce plasma-activated water from distilled water, deionized water, and municipal tap water.According to claim 1, by adjusting the inlet and outlet water flow via the control valves, the system is able to create an adjustable and continuous flow of plasma-activated water.According to claim 1, the plasma-activated water is made by adjusting the distance between the plasma spray and the surface of the channels embedded in the water treatment container, which creates a vortex in the incoming water flow and affects it.According to claim 1, the water treated by the designed system will have antibacterial and disinfectant properties because with the increase in highly reactive species ROS and RNS, free radicals and positive and negative ions, the electrical conductivity and oxidation potential of water decrease and its pH decrease.

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