METHOD FOR THE MICROBIAL DISINFECTION OF WATER-BASED DISPERSIONS CONTAINING LIQUID AND / OR SOLID INGREDIENTS BY MEANS OF HIGH-VOLTAGE IMPULSES

Description

[0001] The invention relates to a method for the microbial disinfection of water-based dispersions containing liquid and / or solid ingredients, such as electrocoating lacquers, using high-voltage pulses. In particular, it relates to a method by which microbes, such as bacteria, algae, and fungal spores, present in water-based dispersions containing liquid and / or solid ingredients, such as electrocoating lacquer, can be at least partially killed. The method enables the electrocoating lacquer to deposit more slowly or not at all on the electrodes compared to conventional solutions. Furthermore, the service life of the electrodes can be increased compared to such conventional solutions. This means that electrode corrosion can be reduced or avoided with a method according to the invention, thus ensuring consistent or longer-lasting efficiency of the electrodes.The chemical properties of the medium or its pH value remain unchanged, and the process can be carried out with low net flow.

[0002] Two processes must be distinguished here: Firstly, bipolar pulses, each with a positive and negative partial charge (i.e., with two high-voltage pulse half-waves of opposite polarity), prevent lacquer deposition on the electrodes of the treatment cell. This avoids the eventual clogging of the treatment cell. Secondly, such bipolar pulses also reduce electrode erosion. Thus, a method according to the invention prevents two disadvantages of using unipolar pulses: (1) lacquer deposition on the electrodes and (2) lacquer coagulation due to a permanent electrochemically induced pH shift.

[0003] In a method according to the invention, the net current should preferably be zero. That is, the current flowing in a first high-voltage pulse half-wave is equal in magnitude to the current in the second half-wave, but with opposite signs or polarities.

[0004] In [1], for example, a surface treatment system for electrocoating is described that can be equipped with a microbial reduction system, which can be operated, for example, using a bypass electroporation process. However, no information is provided therein on how such a process would have to be adapted to achieve the technical effects of a process according to the invention.

[0005] Several sources in the literature already disclose inactivation methods based on electrical pulse treatment, some of which also discuss bipolar pulses as a possible pulse shape for germ reduction. For example, [2] discloses such an inactivation method, which also mentions bipolar pulse shapes. However, this only describes the germ reduction efficiency of different pulse shapes without providing a specification for the application of such pulse shapes to electrocoatings. For example, [3] only compares the efficiency of electrical pulse treatment with unipolar and bipolar exponentially decaying pulses.In [4], only the possibility of using bipolar pulses for the disinfection of liquids by means of electro-pulse treatment is mentioned, but again, no indication is given as to how a process for electrocoating varnishes would have to be adapted to enable microbial reduction on the one hand and to reduce or avoid the deposition of electrocoating varnish on the electrodes on the other. In [5], it is shown that the release of metal ions, Al³⁺ and Fe²⁺ / ³⁺, from the aluminum or stainless steel electrodes is an order of magnitude higher when using unipolar rectangular pulses than when using bipolar rectangular pulses. The released ions can contribute to the contamination of the treated liquid. Furthermore, less corrosion of the metal electrodes is demonstrated when using bipolar pulses. There is no indication of a change in the chemical properties of the medium or the pH by the application of unipolar or bipolar pulses.Bipolar pulses are not mentioned. Nor is the need for a very low net current (when using bipolar pulses) to avoid pH changes or net charge accumulation.

[0006] Further patents dealing with bipolar pulses can be found in the prior art. However, none of these documents provides any indication of the specifications necessary for the application of electro-pulse treatment to electrocoating in order to achieve efficient germ reduction with reduced or avoided electrocoat deposition at the electrodes, without altering the chemical properties or pH value of the electrocoating, and with a low net current. In [6], a method for removing Legionella from aqueous streams by means of electro-pulse treatment with bipolar pulses is disclosed, whereby significantly lower field strengths are required, which are insufficient for the method according to the invention, and furthermore, no specification regarding net current is mentioned. In [7], a method for removing protozoa, in particular free amoebae, from a water stream is disclosed.A method for treating a water flow by means of electrical pulse treatment with bipolar pulses is disclosed. However, the disclosed field strengths are too low to be suitable for a method according to the invention. In [8], a method for treating a water flow with electrical pulses with a field parallel to the flow, pulse chamber, and applications is disclosed, but no bipolar pulses are mentioned. This method describes exclusively unipolar, parallel pulses. [9] It merely discloses a method for producing proteins by electrical pulse treatment using bipolar impulses. However, it remains silent. [9] Regarding inactivation or germ reduction using electro-pulse treatment. In

[10] A liquid treatment device and method are disclosed in which only high-frequency alternating voltage is applied.

[11] A non-thermal disinfection of biological fluids using non-thermal plasma is disclosed, but not an electro-pulse treatment.

[12] A method for treating liquid dairy products with pulsed electric fields and a dairy product produced using this method with bipolar pulses are disclosed. The sterilization of liquid dairy products is described, whereby this is achieved without industrial currents and with lower power.

[13] A coaxial treatment chamber for germ reduction using pulsed electric fields is disclosed. These pulses can be a series of alternative rectangular pulses with no or a short time interval between the pulses. Furthermore, the pulse specifications differ significantly from those of a method according to the invention, due to their application.

[0007] The scientific publication

[16] reveals that electrochemical reactions can occur in pulsed electric field systems used for preserving liquid foods, leading to electrode corrosion and the introduction of particles into the liquid. Furthermore, these phenomena are described, and it is shown that corrosion can be minimized by adjusting the design and pulse shape. The experiments disclosed therein confirm the theory that short pulses and the avoidance of cumulative charges (e.g., by using bipolar pulses) limit corrosion.

[0008] None of the previously described documents discloses a method for the microbial disinfection of water-based dispersions with liquid and / or solid ingredients, e.g., electrocoating varnishes, using high-voltage pulses, which can reduce (kill) or remove the contamination of the electrocoating varnish by microbes and thereby prevent or reduce electrochemical deposition of the electrocoating varnish on the electrodes, and furthermore, leaves the chemical properties of the medium or its pH value unchanged, so that the coating quality of the electrocoating varnish remains unchanged.

[0009] Thus, the objective technical task is to provide a method for the microbial disinfection of water-based dispersions with liquid and / or solid ingredients using high-voltage pulses, which makes it possible to increase the service life of the electrodes, maintain the coating quality of the electrocoating varnish and be energy-efficient to operate.

[0010] The aforementioned objective technical problem is solved by the method disclosed herein according to the subject matter of the first independent claim 1. Related dependent claims describe advantageous embodiments or configurations. Advantageous further developments, which can be implemented individually or in any combination, are presented in the dependent claims.

[0011] In the following, the terms "exhibit," "comprise," or "include," or any grammatical variations thereof, are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, apart from the features introduced by these terms, no other features are present, and to situations in which one or more additional features are present. For example, the expression "A exhibits B," "A encompasses B," or "A includes B" can refer both to the situation in which, apart from B, no other element is present in A (i.e., a situation in which A consists solely of B), and to the situation in which, in addition to B, one or more other elements are present in A, such as element C, elements C and D, or even further elements.

[0012] Furthermore, it should be noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be present once or multiple times, are generally used only once, for example, when the feature or element is first introduced. Upon subsequent mention of the feature or element, the corresponding term "at least one" or "one or more" is generally no longer used, without restricting the possibility that the feature or element may be present once or multiple times.

[0013] Furthermore, the terms "preferably," "in particular," "for example," or similar terms are used in the following in conjunction with optional features without thereby limiting alternative embodiments. Features introduced by these terms are optional features, and it is not intended that these features limit the scope of protection of the claims, and in particular the independent claims. Thus, as the person skilled in the art will recognize, the invention can also be implemented using other embodiments. Similarly, features introduced by "in one embodiment" or by "in another embodiment" are understood as optional features without thereby limiting alternative embodiments or the scope of protection of the independent claims.Furthermore, these introductory expressions are intended to leave all possibilities of combining features introduced herewith other features, whether optional or non-optional features, unaffected.

[0014] In a first embodiment, a method for the microbial disinfection of a water-based dispersion with liquid and / or solid ingredients comprises: providing at least two electrodes arranged relative to each other such that the dispersion can be introduced or passed between them; introducing or passing the dispersion between the electrodes; and applying a previously selectable electrical potential difference to the electrodes such that a sequence of at least two high-voltage pulse half-waves of opposite polarity is generated between the electrodes by the dispersion, wherein: the high-voltage pulse half-waves can be adapted via the potential difference by means of a previously selectable pulse shape, pulse duration, pulse amplitude, and repetition frequency.The pulse duration is selected in a range from 200 ns to 10 µs, the pulse amplitude in a range from 10 kV / cm to 100 kV / cm, and the repetition frequency in a range from 1 Hz to 100 kHz. The high-voltage pulse half-waves are subsequently generated such that the deviation between the total magnitude of the positive and negative partial charges is at most 10% of the respective larger partial charge magnitude of the positive and negative partial charges, and the time interval between two high-voltage pulse half-waves is at most 10 times the duration of the first high-voltage pulse half-wave. Optionally, when using bipolar high-voltage pulses, the second pulse half-wave can be adapted to the first pulse half-wave such that the total charge flow of the positive and negative partial pulses Q = Q+ + Q- is preferably zero, i.e., preferably Q+ + Q- = 0 or Q- = 0.

[0015] In a further embodiment, the deviation between the total amount of the positive and negative partial charges is at most 5%.

[0016] In a further embodiment, the deviation between the total amount of the positive and negative partial charges is 0%. That is, the amounts of the two partial charges (positive and negative) are equal.

[0017] In a further embodiment not according to the invention, a relationship between repetition frequency (f) and flow rate (Ø) of the dispersion between the electrodes is given by: f = ∅ ⋅ W W 1 ⋅ 1 V 0 . Where W is the specific treatment energy, W1 is the specific energy of a pulse, and V0 is the treatment volume of the treatment chamber.

[0018] In another embodiment, the time interval between two high-voltage pulse half-waves is also equal to 0.

[0019] In another embodiment, the dispersion is also an electrocoating lacquer for cathodic and anodic dip coating.

[0020] In a further embodiment, the dispersion with liquid and / or solid ingredients further comprises at least one medium from the group of dispersions, or is formed from such a group, wherein this group includes: cooling water, deionized or fully ionized (DI) water, industrial water, wastewater, rinse water from washing plants, liquid foodstuffs, drinking water, milk, juice or soups.

[0021] Advantages of the method described herein include, for example, the use of electrical impulse treatment for disinfection or germ reduction in electrocoating baths, and the avoidance or reduction of paint deposition on the electrodes of the treatment cell by applying a specific impulse shape.

[0022] Such a method according to the invention comprises the application of bipolar high-voltage pulses (rectangular or other pulse shapes, cf. FIG. 4 )For germ reduction in electrostatic immersion baths with a pulse duration of the high-voltage pulse half-wave in the range of 200 ns to 10 µs. The bipolar pulse shape must be selected such that the total charge flow of the positive (Q+) and negative (Q-) partial pulses Q = Q+ + Q- is preferably zero, or the deviation of the magnitudes of Q+ and Q- of the positive and negative partial pulses is less than 5%, based on the larger magnitude of Q+ and Q-. By generating bipolar pulses with very small deviations (positive vs. negative) in the charge flow, the net charge accumulation at the electrodes is minimized. By reversing the voltage (i.e., by applying bipolar pulses), oppositely charged ions are generated at the electrodes, which neutralize the already generated, existing ions, thus preventing the electrochemical processes of lacquer deposition.The pulse duration of the partial pulses must be chosen to be so short (i.e., < 10 µs) that the accumulation of hydroxide and hydronium ions by flushing during flow operation is prevented. This will result in only a minimal or no change in the pH value at the electrodes, consequently preventing varnish deposition on the electrodes of the treatment cell and the formation of coagulates in the varnish. The inactivation efficiency is not affected by the choice of pulse durations (partial pulses 200 ns < partial pulse duration < 10 µs) and pulse amplitudes (IEI > 10 kV / cm).

[0023] The following media can be treated using a method according to the invention: electrocoating lacquer, other aqueous liquids such as cooling water, demineralized water, industrial water, wastewater, rinse water from washing systems, liquid foodstuffs (e.g. beverages of all kinds, etc.), juice, soups, milk or dairy products, etc.

[0024] The following pulse shape can be used: bipolar, whereby any partial pulse shapes are applicable.

[0025] The total charge actually transferred by the positive and negative partial charges during a bipolar pulse, i.e., the two high-voltage pulse half-waves, is preferably zero. A sequence of bipolar pulses with a pulse repetition frequency up to the kHz range can be used.

[0026] The deviation ΔQ = |Q +< - |Q -< | | may be a maximum of 10%, preferably 5%, based on the larger partial charge amount, whereby preferably |Q +< |=|Q -< |, i.e., that the two partial charges of the high-voltage pulse half-waves have the same amount.

[0027] The pulse duration is in a range of approximately 0.2 µs to approximately 10.0 µs and the pulse amplitude is in a range of approximately 10 kV·cm -1< to approximately 100 kV·cm -1< .

[0028] The pause time (time interval, Δt) between the first (e.g., positive) and the second half-wave (e.g., negative) should not be longer than 10 times the pulse duration (e.g., with a pulse duration of 1 µs, the interval Δt, or the duration between the first half-wave and the second half-wave, should be less than 10 µs), preferably the duration between the first half-wave and the second half-wave is 0 s.

[0029] Electrodes for the method described herein may comprise, or at least partially consist of, an electrically conductive material from the group of electrode materials, which includes: metal, copper, aluminum, steel, stainless steel, graphite, gold, silver, platinum, or an alloy thereof, or one of the aforementioned materials coated with diamond or titanium. The electrode surfaces may optionally be chemically passivated.

[0030] The flow of the electrocoating varnish between the electrodes can be laminar or turbulent.

[0031] The electric charge (Q 1< ) that flows during a high-voltage pulse half-wave is given by the integral of the current flow (I 1 ): Q 1 = ∫ 0 Δ t 1 I 1 dt

[0032] The electric charge that flows during the second high-voltage pulse half-wave (Q 2< ) is given by: Q 2 = ∫ 0 Δ t 2 I 2 dt , where I 2 is the current flow of the second half-wave.

[0033] The second high-voltage pulse half-wave must be chosen such that the total charge flowed (Q) of the first and second partial pulses Q = Q₁< + Q₂< is ideally equal to zero, or the deviation of the magnitudes of Q₁< and Q₂< of the first and second partial pulses is less than 10%, relative to the larger magnitude of Q₁< and Q₂<. This corresponds to the condition: Q = Q 1 − Q 2 ≤ 0 , 10 Or: Q 1 − Q 2 max Q 1 Q 2 ⋅ 100 ≤ 10 %

[0034] This leads to the equation: Q 1 = ∫ 0 Δ t I 1 dt ≅ Q 2 = ∫ 0 Δ t I 2 dt ,

[0035] Regarding the dependence of specific treatment energy on frequency and flow rate: To ensure high disinfection efficiency of the electro-pulse treatment even in flow-through applications (above 1 log reduction; i.e., more than 90% killed), the applied specific treatment energy (W) must generally be above 40 J·ml. At very high flow rates (more than 100 liters (l) per hour (h)), this input is only guaranteed by a high pulse repetition frequency (f). The relationship between the flow rate (Ø) and frequency is described below. The flow rate is given by: ∅ = V ˙ = dV dt ; where V represents the volume and t represents time.

[0036] Assuming that the mean dwell time ( <t>) of an infinitesimal volume unit in the treatment cell, with volume V 0 , for a non-laminar flow is given by the following Eq: T = V 0 ∅ ; This results in the average number of impulses ( <n>) which receives an infinitesimal volume unit during flow through the treatment chamber: N = f ⋅ T = f ⋅ V 0 ∅ ;

[0037] The total specific treatment energy (W) is the product of the number of pulses and the energy of one pulse: W = W 1 ⋅ N ;

[0038] From equations (1)-(4) the specific treatment energy is: W = W 1 ⋅ f ⋅ V 0 ∅ ;

[0039] One can see from the equation. (10), that the specific treatment energy can be increased by doubling the flow rate, by doubling the frequency or the specific energy of a single pulse, but also by simultaneously increasing (adjusting) the pulse energy and frequency.

[0040] In a method according to the invention, flow rates in a range from 2 l / h to 100 m³ / h can be treated.

[0041] Examples of microbes that can be reduced or removed by means of a method according to the invention are bacteria, algae and fungal spores.

[0042] Before a car body or other goods receive a topcoat, the surface must be cleaned and pretreated. It also receives a protective layer against corrosion. This is achieved through surface pretreatment and electrophoretic dip coating. The latter is an electrochemical process that uses a direct current field in an electro-immersion bath to create a uniform coating film. However, bacteria can multiply in the water and coatings used, potentially compromising the surface coating. To reduce the bacterial load, pulsed high-voltage technology can be used as an alternative to biocide preservation. The medium to be treated is pumped through a treatment cell consisting of two opposing electrodes and a plastic housing. Short high-voltage pulses are applied to the electrodes. The resulting electric field pulse in the medium causes electroporation of the cell membrane.As a result of electroporation, the bacteria die. This is also referred to as irreversible electroporation, where electroporation encompasses all pores created, i.e., both reversible (pores that close again) and irreversible pores.

[0043] However, when using electro-pulse treatment in electrocoating, there is a risk of electrochemical coating deposition on the electrodes of the treatment cell and coagulation of coating particles within the coating. These processes arise from the following: When a voltage is applied in aqueous solutions, the dissociation of water produces hydroxide (OH⁻) and hydronium ions (H₃O⁺), which migrate to the anode and cathode, respectively, and accumulate there. This changes the pH in the immediate vicinity of the electrode surface. This pH change leads either to electrochemical coating deposition on the electrode or to the formation of coating coagulates within the coating. A coating layer on the treatment electrodes would reduce the inactivation efficiency and significantly shorten the electrode's service life.Electrochemical coagulation of the lacquer, resulting from the electrical pulse treatment, would impair the surface coating and block the treatment cell. Our method is designed to prevent lacquer deposition on the treatment electrode without affecting the inactivation efficiency or the composition of the lacquer (i.e., without causing any chemical changes or coagulation of the lacquer).

[0044] The advantage of a method according to the invention is to use the electrical pulse treatment for germ reduction in immersion coating baths and to avoid or reduce the paint deposition on the electrodes of the treatment cell by applying a specific pulse shape.

[0045] Essential features of the invention include: The application of bipolar pulses (rectangular or other pulse shapes) for germ reduction in electro-immersion baths with a pulse duration of the individual pulses from 200 ns to 10 µs. The bipolar pulse shape must be selected such that the total charge flowed from the positive and negative partial pulses Q = Q< + Q< is ideally equal to zero, or the deviation of the magnitudes of Q< and Q< of the positive and negative partial pulses is less than 10%, preferably less than 5%, based on the larger magnitude of Q< and Q< (see above).

[0046] If unipolar pulses (with any pulse shape) are used, as is mostly the case, unwanted color deposition occurs on the electrodes of the treatment cell, which damages the electrocoating and ultimately blocks the treatment chamber.

[0047] To prevent lacquer deposition on the electrodes and the formation of lacquer coagulates in the lacquer, the following key mechanisms are used: (1) The pulse duration is selected to be so short (i.e., less than 1 µs) that the accumulation of hydroxide and hydronium ions is prevented by flushing them away in the flow. This prevents pH changes at the electrodes and in the medium. (2) By reversing the voltage during a pulse (i.e., by using bipolar pulses), ions with opposite charges are generated at the electrodes, which neutralize the ions already present, thus preventing the transient processes of lacquer deposition. (3) By generating bipolar pulses with very small differences in the overall charge (positive charge vs. negative charge), the accumulation of a net charge at the electrodes is minimized or avoided.(4) The inactivation efficiency is not affected by the choice of pulse duration (bipolar from 200 ns) and pulse amplitudes (from 10 kV / cm). (5) By rapidly reversing the voltage in an interval Δt, not longer than 10 times the pulse duration of a half-wave, preferably towards zero, so that the accumulated charges are compensated by opposite charges before the deposition condition is reached (or the reaction has started).

[0048] The process enables the application of electro-pulse treatment for the microbial disinfection of electrocoatings with consistent inactivation efficiency, without impairing the paint quality and without unwanted coating of the electrode surface in the treatment cell.

[0049] The application of bipolar pulses for nucleation reduction in electrocoating paint, characterized by the fact that the total charge flowed during a bipolar pulse is zero or very small, but the deviation between the charges flowed during the partial pulses is less than 10%, preferably less than 5%, based on the larger partial charge amount, proves to be advantageous.

[0050] To date, there are no alternative physical treatment methods for reducing microbial contamination in electrocoatings that guarantee the quality of the coating and thus the flawless coating of the workpiece. Thermal treatment methods lead to coagulation of the coating, while UV and ultrasonic treatments lead to chemical degradation. Microbial inactivation using electro-pulse treatment, which is based on the phenomenon of electroporation of the cell membrane, is currently the only known physical treatment method that is also effective in turbid media (microbial reductions of more than 3 log steps; bacterial inactivation of > 99.9%) and has no direct effect on the molecular structure of the medium being treated. Furthermore, unlike chemical treatments or UV irradiation, no bacteria resistant to the treatment are induced.

[0051] By applying bipolar pulses with a very low or negligible total charge during the pulse, it is ensured that no permanent pH change is induced in the lacquer or at the treatment electrodes. Thus, no lacquer deposition or coagulation occurs on the electrodes. The net charges generated are so small that they are further diluted by the material flow (flow rate in the treatment chamber), and therefore the chemical properties of the lacquer remain unchanged. Brief description of the characters

[0052] Further details and features of the present invention will become apparent from the following description of a preferred embodiment, particularly in conjunction with the dependent claims. The respective features may be implemented individually or in combination with one another. The invention is not limited to the embodiments or forms described.

[0053] The exemplary embodiments are shown schematically in the following figures. Here, identical reference numerals in the figures denote identical or functionally equivalent elements, or elements corresponding to each other with respect to their functions.

[0054] For illustrative purposes and without limiting effect, further features and advantages of the invention will become apparent from the description of the attached Drawings. They show: Fig. 1 a schematic representation of a first embodiment of a method according to the invention as claimed in claim 1; Fig. 2 a schematic representation of an exemplary, trapezoidal, bipolar high-voltage pulse with two high-voltage pulse half-waves; Fig. 3 a schematic representation of three exemplary electrode arrangements; and Fig. 4 A schematic representation of five exemplary high-voltage pulse shapes. Detailed description

[0055] FIG. 1 schematically shows an embodiment of a method (100) for the microbial disinfection of a water-based dispersion containing liquid and / or solid ingredients. The process includes (100): Provide (110) of at least two electrodes arranged in such a way that the dispersion can be introduced or passed through between them; introduction or passing through (120) the dispersion between the electrodes; and applying pressure (130) The electrodes are subjected to a previously selected electrical potential difference. The application (130) The dispersion is configured such that a sequence of at least two high-voltage pulse half-waves with opposite polarity between the electrodes is generated. The high-voltage pulse half-waves can be adjusted via the potential difference using a pre-selectable pulse shape, pulse duration, pulse amplitude, and repetition frequency. The pulse duration is selected from 200 ns to 10 µs, the pulse amplitude from 10 kV / cm to 100 kV / cm, and the repetition frequency from 1 Hz to 100 kHz. The sequence of high-voltage pulse half-waves is generated such that the deviation between the total magnitude of the positive and negative partial charges is at most 10%, based on the respective larger magnitude of the positive and negative partial charges.The time interval between two high-voltage pulse half-waves is at most 10 times the duration of the first high-voltage pulse half-wave.

[0056] FIG. 2 shows the temporal course of the current flow (I) during an exemplary bipolar, discontinuous, trapezoidal high-voltage pulse consisting of a positive and a negative high-voltage pulse half-wave, whereby the negative half-wave can also occur first and where the high-voltage pulse can also be formed with other pulse shapes (cf. FIG. 4 ), with the following characteristics: amplitude of the current flow I₁ or I₂, pulse half-wave durations Δt₁ or Δt₂, area 1 = area 2, permissible deviation max. 10%. Pause time (Δt) preferably approaching zero, but not longer than 10 times the duration of a half-wave. It is known that parasitic reactions already occur from a duration of 2 µs (pause / interval, Δt = 2 µs).

[0057] FIG. 3 shows different electrode configurations in the treatment reactor (see dissertation)

[14] , Page 29, Figure 2.10) for the electrical pulse treatment in flow (cross-section drawing): 1. plane-parallel electrodes, 2. coaxial arrangement and 3. collinear arrangement.

[0058] FIG. 4 shows typical bipolar pulse shapes (see

[15] , Page 8, Fig. 3 ) which can be used: (1) bipolar, discontinuous trapezoidal, (2) bipolar, discontinuous triangular, (3) bipolar, discontinuous rectangular, (4) bipolar, discontinuous exponential and (5) bipolar, discontinuous sinusoidal. Reference symbol list

[0059] 100 Methods for microbial disinfection or germ reduction of water-based dispersions with liquid and / or solid ingredients 110 Providing at least two electrodes 120 Introducing or passing water-based dispersions containing liquid and / or solid ingredients between the electrodes 130 Applying a previously selected electrical potential difference to the electrodes Bibliography

[0060] [1] .......... US 2019 0 308 311 A1 [2] .......... W. Frey, C. Gusbeth, T. Schwartz (2013) "Inactivation of Pseudomonas putida by Pulsed Electric Field Treatment: A Study on the Correlation of Treatment Parameters and Inactivation Efficiency in the Short-Pulse Range", Journal of Membrane Biology, 05 / 2013 [3] ..........Keith, WD, Harris, LJ, & Griffiths, MW (1998). "Reduction of bacterial levels in flour by pulsed electric fields". J. Food Proc. Eng., 21,263-269. [4] .......... J. Raso, W. Frey, G. Ferrari, G. Pataro, D. Knorr, J. Teissié, D. Miklavčič, "Recommendations guidelines on the key information to be reported in studies of application of PEF technology in food and biotechnological processes", Innovative Food Science & Emerging Technologies, Volume 37, Part C, 2016, Pages 312-321, ISSN 1466-8564 https: / / doi.org / 10.1016 / j.ifset.2016.08.003 [5] ..........Kotnik, T., Miklavčič, D., & Mir, L. M. (2001). "Cell membrane electropermeabilization by symmetrical bipolar rectangular pulses". Part II. Reduced electrolytic contamination, Bioelectrochemistry, 54, 91-95. [6] .......... WO 2000 062 822 A1 [7] .......... WO 2000 062 821 A1 [8] .......... WO 2000 063 355 A1 [9] .......... WO 2002 033 065 A3

[10] ........ US 2015 0 114 913

[11] ........ US 2004 0 022 669

[12] ........EP 2 543 254

[13] ........ US 2016 0 031 728

[14] ........Dissertation: Toepfl, Stefan. (2006). Pulsed Electric Fields (PEF) for Permeabilization of Cell Membranes in Food- and Bioprocessing Applications, Process and Equipment Design and Cost Analysis. 10.14279 / depositonce-1441; page 29, Figure 2.10.

[15] Master's Thesis: Führer, Rudolf. (2012). Influence of high-voltage pulses on the properties of potato starch and texture. urn:nbn:de:gbv:519-thesis2012-0631-5, page 8. Fig. 3 .

[16] ........ Morren, J.; Roodenburg, B.; de Haan, SWH; (2003). Electrochemical reactions and electrode corrosion in pulsed electric field (PEP) treatment chambers. Innovative Food Science & Emerging Technologies, Volume 4 (Issue 3), Pages 285-295. https: / / doi.Org / 10.1016 / S1466- 8564(03)00041-9.< / n> < / t>

Claims

1. Method (100) for the microbial disinfection of a water-based dispersion with liquid and / or solid ingredients, comprising: a. providing (110) at least two electrodes, which are arranged in relation to one another in such a way that the dispersion can be guided in between them or through them; b. guiding (120) the dispersion in between or through the electrodes; and c. imposing (130) on the electrodes a preselectable electrical potential difference in such a way that a sequence of at least two electrical high-voltage pulse half-waves of opposing polarity is formed between the electrodes by the dispersion, wherein: i. the high-voltage pulse half-waves can be adjusted over the potential difference in each case by means of preselectable pulse shapes, pulse duration, pulse amplitude, and repetition frequency, ii. the pulse duration is selected in a range from 200 ns to 10 µs, and the pulse amplitude in a range from 10 kV . cm-1 to 100 kV . cm-1, and the repetition frequency in a range from 1 Hz to 100 Hz, iii. The high-voltage pulse half-waves in the sequence are formed in such a way that the deviation between the sum total of the positive and negative part loads amounts to a maximum of 10% in relation to the respective greater part load value of positive and negative part loads, and iv. the time interval between two high-voltage pulse half-waves amounts at the most to 10 times the duration of the first high-voltage pulse half-wave.

2. Method according to claim 1, wherein, further, the deviation between the sum total of the positive and negative part loads amounts to a maximum of 5%.

3. Method according to claim 1, wherein, further, the deviation between the sum total of the positive and negative part loads amounts to 0%.

4. Method according to any one of claims 1 to 3, wherein, further, the time interval between two high-voltage pulse half-waves is equal to 0.

5. Method according to any one of claims 1 to 4, wherein, further, the dispersion is an electronic immersion lacquer for cathodic and anodic dip immersion lacquer application,6. Method according to any one of claims 1 to 5, wherein, further, the dispersion comprises at least one dispersion from the group with liquid and / or solid ingredients, or is formed from this group, wherein this group comprises: Cooling water, fully demineralised water, industrial water, waste water, flushing water from washing systems, liquid foodstuffs, drinking water, milk, juice, or soups.

7. Use of one of the methods according to any one of claims 1 to 5 in a cathodic and anodic immersion lacquering process.