MXPA98009539A - Processing for microbial control in food processing equipment used by ozonizac - Google Patents

Abstract

The invention relates to the treatment of aqueous streams and aqueous systems with ozone. The aqueous streams comprise a closed loop system that provides transportation from a production site to a processing site for a variety of products. The aqueous stream may contain a test soil charge and a microbial load. A treatment zone is defined through which the aqueous current passes. The treatment zone is contacted with a sufficient concentration of ozone to substantially reduce the microbial population and to substantially reduce the number of microorganisms that can generate silt inside the system. An amount of ozone is added to the aqueous stream in the treatment zone such that once the microbial populations are reduced to a level of safety, the concentration of ozone is also reduced to a substantially safe level for contact with operating personnel and product. . Typically, such a concentration is less than a part of the weight of ozone per million parts by weight of the aqueous system, preferably less than 0.5 parts by weight of ozone per million parts of the aqueous system. The use of a treatment zone in an aqueous system secretes the release ozone to areas frequented by operating personnel, sensitive materials or product

Description

PROCESS FOR MICROBIAL CONTROL IN AUGMENTATION PROCESSING EQUIPMENT USING OZONIZATION FIELD OF THE INVENTION The invention relates to the control of a microbial population and the use of an antimicrobial composition in a system or aqueous stream containing a test soil charge comprising a food, a particulate food, soil and microorganisms. The invention also relates to the treatment of aqueous systems with a composition that reduces the microbial population and in particular to systems that reduce the population of microorganisms that generate silt. More specifically, the invention relates to the use of antimicrobial oxidant in a separate treatment zone to reduce microbial populations in a small portion of the aqueous flow containing a test soil charge.

BACKGROUND OF THE INVENTION Water has been used as a means of transport to move a product from a place of production to a place of processing or use for many years. A variety of materials that can be floated or suspended or dissolved in water have been transported using a moving current. Examples of such materials include products of a wood industry, coal in a coal slurry, agricultural products such as fruits and vegetables, particulate products with aqueous polymerization, and many others to mention. A consistent design feature of these systems is the use of a closed loop aqueous stream that returns the aqueous medium to its source. The aqueous stream that transports the material from the place of production to the place of processing is often returned, without product, to the place of production by new product for transport. Such recycled water streams that are continuously reused acquire a land charge that can sustain the growth of microbial populations and in particular slime-producing microorganisms. Such closed flow water systems can obtain and accumulate substantial concentrations of impurities from the environment and the product transported in the closed loop system. Such a load of test soil can pose even more substantial problems in the event that the product is of biological origin including products such as wood, wood fiber, fruits, vegetables, etc., or other products that comprise substantial amounts of compositions of carbohydrates, lipids or proteins that can act as a food source for microorganisms. A need for effective antimicrobial agents and processes to prevent or reduce microbial populations is apparent.

Ideally, an antimicrobial agent or compound used in such a system will have several important properties in addition to its antimicrobial efficacy. The compound or agent should not have residual antimicrobial activity on the food after processing. The residual activity implies the presence of a film of antimicrobial material that will continue to have an antimicrobial effect which may require additional rinsing of the food product. The antimicrobial agent should preferably be odor free to avoid transferring undesirable odors to food. The antimicrobial agent should also be composed of direct additive materials for food that will not affect food if contamination occurs, nor will it affect humans if incidental ingestion results. In addition, the antimicrobial agent should be preferably composed of, or should result in, harmless or naturally occurring ingredients, which are chemically compatible with the environment and do not cause concern for toxic waste within the slide water.

A common water transport system comprises a slide system. Such systems are used in agriculture to transport an agricultural product such as fruits or vegetables from a production site, typically a tillage field or a garden plot to a processing site., to wash and pack it using an aqueous stream. Fruits or vegetables are cleaned, treated and packaged for distribution at the processing site. Such slide systems can contain large volumes of water flowing at a rate of about 20 to 4000 liters per minute. Such slide systems can transport substantial quantities of fruits or vegetables from a production site to a processing site. Such systems can transport approximately 4.54 to 454 kg of fruits or vegetables per minute or more, on a continuous basis during production operations. Such slipstreams become inherently contaminated with soil, fruit and vegetable fragments, fragments of plants, and other agricultural by-products. Such a slipstream is a potent means to promote the growth of microorganisms. Untreated sludge water can quickly become contaminated with large microbial populations. As a result of the growth of slime-forming microorganisms, the surfaces of the aqueous system can be quickly coated with silt-producing colonies and the silt by-product.

The test soil charge may comprise a substantial proportion of the aqueous stream, commonly about 0.1 to 20% by weight of the aqueous stream, more commonly about 1-15% by weight of the aqueous stream.

Most common treatments for reducing populations of such microorganisms comprise contacting the slipstream, in any arbitrary position in the closed loop, with chlorine (Cl2) or an antimicrobial composition containing or giving chlorine. Such antimicrobials include chlorine gas (Cl2), chlorine dioxide (CIO2), sodium hypochlorite (NaCIO), chlorinated isocyanurate compounds or other chlorinated compounds that can generate a concentration of sanitizing or antimicrobial chlorine in the aqueous stream. Chlorine is a well-known antimicrobial material and is often very effective in controlling microbial growth. However, the use of such chlorinated materials often have substantial drawbacks including corrosion of equipment and danger to operating personnel. The rate of use of these antimicrobials is very high because they tend to be consumed quickly by the high organic load in the aqueous stream. In addition, when consumed, compounds such as chlorine gas or chlorine dioxide decompose producing by-products such as chlorites and chlorates, while hypochlorite produces trichloromethanes that can be toxic at very low concentrations. Finally, chlorine dioxide is a toxic gas with an acceptable limit of air concentration of 0.1 ppm. Exposure to CIO2 often causes headaches, nausea and respiratory problems, requiring expensive and intricate safety devices and equipment when used. Iodofor antimicrobial agents have also been used for various aqueous antimicrobial applications. However, iodofor compounds tend to decompose or may be lost by evaporation when used in an aqueous medium. Thus, long-term activity requires a high concentration of iodofor. As a result, there is a substantial need in the food processing industry to provide a food transport means that also controls the loading of microbial soil without the use of high concentrations of antimicrobials such as compounds that release chlorine or other halogenated constituents. A number of attempts have been made to rectify the problems caused by chlorinated substances in such materials. One attempt refers to the use of peracetic materials in creek water. Lokkesmoe et el. , Patent of E.U. , No. 5,409,713 teaches the use of peracetic acid in an antimicrobial function to treat creep water. The use of other antimicrobial agents in the control of microorganisms is well known for several applications. For example, Grosse Böwing et al. , Patents of E.U. Nos. 4,051,058 and 4,051,059 use peracetic acid as a sanitizer in a variety of applications. In addition, Greenspan et al., U.S. Patent No. 2,512,640 teaches the use of a peracetic acid composition comprising 500 ppm or more of peracetic acid for the treatment of various fruit and vegetable compositions in a spray applicator. Greenspan et al., Food Technology, Vol. 5, No. 3, 1951, similarly describes spray compositions that can be applied to fresh fruits and vegetables comprising peracetic acid. Langford, U.S. Patent Application. GB 2 187 958 A describes the use of peracetic acid and propionic acid for the treatment of fungi in microbial pathogens of plants in growing plants and especially edible crops. In other publications, Baldry et al. , "Disinfection of Sewage Effluent with Peracetic Acid", Wat. Sci. Tech., Vol. 21, No. 3, pp. 203-206, 1989; and Poffé et al. , "Disinfection of Effluents from Municipal Sewage Treatment Plants with Peroxy Acids", Zbl. Bakt. Hyg. I. Abt. Orig. B 167, 337-346 (1978) both describe the use of peroxy acids for the treatment of effluent streams and municipal wastewater applications. Hutchings et al. , "Comparative Evaluation of the Bactericidal Efficiency of Peracetic Acid, Quaternaries, and Chlorine-Containing Compounds", Society of American Bacteriologists, Conference Summaries Presented at the 49th General Board, describes the general effectiveness of peracetic acid compared to several other compounds antimicrobial Additionally, Branner-Jorgensen et al. , Patent of E.U. , No. 4,591, 565 describes the reduction of thermal stability of setting through the use of aliphatic or inorganic aqueous base peroxy acids. Block, "Disinfection, Sterilization, and Preservation," Fourth Edition, Chapter 9, pages 167-181, describes the various characteristics and attributes of peroxygen compounds. However, generally the art has taught against the use of percarboxylic acids in aqueous streams due to concerns of compound stability in the presence of high concentrations of organic matter.

Hurst, U.S. Patent No. 5,053,140 teaches a water treatment facility designed to remove solids, grease, bacteria and other impurities from the water used in food processing. The bulk water is subjected to a number of purification steps that include a countercurrent contact with an ozone stream. Abiko, Japanese Patent Application Kokai No. 4-145997 teaches a similar purification unit. Avvakumov et al., Inventor Certificate No. 858735 of the USSR, and other patents teach the addition of ozone to fresh water inputs, or to clean replacement water, to a processing area or directly to the water transport area of the USSR. slide. Such schemes maintain a relatively fine-grained ozone concentration in bulk transportation water during the movement of product from the place of production to the place of use. Beuchat, "Surface Disinfection of Raw Produce," Dairv Food and Environmental Sanitation. Vol. 12, No. 1, and other references teach the use of direct application of gaseous or aqueous ozone to bulk water to obtain control of microbial population. T. R. Bott, "Ozone as a disinfectant in process plant", Food Control, discusses in general terms the use of ozone in disinfectant applications in general. As a whole, Bott teaches the direct application of relatively small concentrations of ozone against surfaces to disinfect and clean. Bott suggests relatively clean water with reduced ozone concentrations (approximately 0.1 ppm) for control. Sumí, JP 60-202229 and Shieno, JP 62-206536 put food in contact with pre-ozonated aqueous solutions to effect microbial control. Shieno teaches a method of food sterilization using pre-ozonated solutions to effect microbial control in a system that uses circulated water that has no test charge that comprises microorganisms or soil. Shieno uses ozone with organic auxiliaries that have a relatively corrosive pH of 3-5. Finally, Shieno apparently does not use a circulated / recirculated system. Sumí et al., Teaches a washing, food sanitizing device where the ozone is dispersed in an open tank containing bulk water, i.e., greater than 50% by weight of the service water. Bulk water treatment is done in an open container. Due to the unpleasant / toxic nature of ozone, contact with any food, or contact with a processing surface or an aqueous stream with ozone can cause worker discomfort or other problems. In addition, attempts to treat large volumes of aqueous streams require substantial ozone generation equipment.

Typical commercial applications described for slide systems attempt microbial control using ozone applications in replenishment water - usually potable - bulk or backfill. Other processes involve direct food contact between food and ozone All these applications are based on the premise that high-demand, land-based waters will generally reduce or eliminate ozone concentration and render ozone ineffective in waters with high demand for microbial control. . Due to this concern that large concentrations of test soil loads will avoid microbial control using ozone, the prior art has focused on the treatment of clean water with ozone at or near the introduction of the replacement water to the slide system. These approaches result in potential ozone gasification which can create a hazard for operating personnel or equipment corrosion. In addition, ozone in direct contact with food material can degrade the appearance or nutritional quality of the food. In addition, these processes require a relatively large ozone consumption in such systems to maintain a high concentration of residual ozone for effective microbial killing. Typically, a residual ozone target of between 0.1-10 ppm of ozone in water is required. Therefore, there is a substantial need for treatment systems that can effectively use ozone to control microbial populations without any direct contact of significant concentrates (greater than 1 ppm of ozone with large volumes of processing water, food items, processing surfaces of the general environment that It surrounds the processing facilities, however, the use of ozone must successfully reduce microbial populations as long as it does not cause significant corrosion or other chemical attack on production facilities.

BRIEF DESCRIPTION OF THE INVENTION We have discovered that microbial control can be achieved in a variety of closed aqueous cycle processing systems if a small fixed proportion of the aqueous recycle containing a test ground charge stream is directed, on a continuous flow basis, through of a treatment zone for contact with ozone. Within the treatment zone, the aqueous stream is brought into contact with a high concentration of ozone. Ozone reacts with particulate feed, soil and microbial population in the test soil load. As the ozone reacts with the charge and reduces the microbial population, the concentration of ozone is also reduced proportionally. An amount of ozone is used such that after treatment the concentration of ozone in the stream leaving the zone is not harmful, irritating or harmful. Preferably the ozone concentration is reduced to a concentration which prevents gasification or other undesirable effects related to ozone, typically to less than 1 ppm, preferably less than 0.1 ppm of 03 in water. After the treatment is complete, the continuous aqueous flow leaves the treatment zone having reduced microbial populations and substantially reduced ozone concentrations. During processing, the aqueous ozone concentration can range from greater than one to about 50 ppm. However, at the exit of the treatment zone, the ozone concentration is typically less than 1 ppm and can be as small as 0.1 ppm depending on the process conditions. Using a treatment zone, ozone is confined to a small volume of the aqueous stream where the aqueous stream is exposed to significant concentrations of ozone that can remove substantially all microbes from the stream. The processing equipment, other than that of the treatment zone, is not brought into contact with ozone at any substantial concentration. Additionally, no product transported using the aqueous stream is brought into direct contact with substantial amounts of ozone. In addition, no production personnel, in contact with the aqueous stream, transported product or associated equipment, have contact with active ozone at any significant concentration during operations.

The invention involves treating recycled water of moderate to high demand containing substantial quantities of a test soil charge comprising dissolved earth, feed, bacteria and other microbes (the test soil load comprising up to 10% by weight in the stream of slide water but typically between 0.1-3% by weight) to effect microbial reduction or elimination. This process uses a localized treatment zone, high ozone content, short contact time. Even in a high demand system with food and other proven land, the use of ozone at an effective concentration can effectively kill microorganisms and reduce such populations. The amount of ozone put in contact in the treatment zone depends on the content of the tested soil. An amount of ozone is selected such that the ozone reacts with the microbial populations and the rest of the soil load tested such that the ozone concentration is less than about 0.1 ppm just before leaving the treatment zone. We believe that using the process of this invention, the problems related to the use of ozone in potable clean replacement water can be avoided and the ozone consumption can be substantially reduced while still achieving effective microbial control. We believe that ozone consumption can be reduced two to ten times over ozone systems of the previous art. The process of the invention is unexpectedly effective to prevent the growth of unwanted microorganisms in food transport apparatus. Ozone consumption is unexpectedly low in view of the organic load of fruits or vegetables and microbial soils within the slide water. The process of the invention provides an aptimicrobial agent useful in the process of water for transporting food products which has a high degree of antimicrobial efficacy and which is ingestible safely by humans while not imposing environmental incompatibility.

Differentiation of "acid" or "static" antimicrobial activity, definitions that describe the degree of efficacy, and official laboratory protocols to measure this efficacy are important considerations in understanding the relevance of antimicrobial agents and compositions. The antimicrobial compositions can effect two types of microbial cell damage. The first is a truly lethal, irreversible action that results in complete destruction or incapacitation of a microbial cell. The second type of cell damage is reversible, so that if the organism is left free or the agent, it can multiply again. The first is qualified bactericidal and the last, bacteriostatic. A sanitizer and a disinfectant are, by definition, agents that provide antibacterial or bactericidal activity. In contrast, a preservative is generally described as an inhibitory or bacteriostatic composition. For the purpose of this invention, the term "test soil loading" means material dissolved or suspended in an aqueous stream. Such material may comprise food particulate, food waste, agricultural soil, microbial spores, organisms, cell walls, and other microbial components and by-products. The term "treatment zone" means a conduit or container operating either continuously or continuously having a volume of less than 10% by volume of the total aqueous stream, preferably less than 1% of the total aqueous stream where the aqueous stream containing a test soil charge is contacted with ozone in gas or aqueous phase. In a treatment zone, the ozone is kept in a closed container or conduit until it is substantially consumed during its use as a microbial control agent. Using such a treatment zone, little free ozone is released from the aqueous stream because it is completely consumed substantially during contact with the test soil charge in the treatment zone. The treatment zone typically comprises a closed volume that prevents loss of ozone from the aqueous stream to the atmosphere. In addition, the treatment zone may contain means for introducing ozone into the aqueous stream in gaseous, aqueous or gaseous aqueous mixed phase. Finally, the treatment zone may contain means for stirring the ozonated water, the aqueous stream and the test ground charge to effect appropriate contact between ozone and microbes or microbial generating constituents.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram representation of a slide system. This diagram is usually representative of slide systems. However, a variety of slide systems appear in different configurations. Fig. 2 is a block diagram representation of a second slide system. This diagram is generally representative of a slide system with a different type of treatment zone arrangement for treating an aqueous stream derived from another portion of the slide apparatus. Figs. 3-6 are graphical representations of microbial control using various proportions of ozone in an aqueous stream having test soil loads ranging from less than 1% by weight to greater than 6% by weight. FIG. 7 is a graphical representation of ozone concentration measured qualitatively using an oxidation-reduction probe (ORP). Fig. 8 is a graphic representation of the use of the ORP measurement to verify the absence of residual slide ozone when a topsoil load is present.

DETAILED DESCRIPTION OF THE INVENTION The process of this invention involves contacting an aqueous stream containing a test soil charge containing microbes or microbial generating colonies with an effective concentration of ozone in a treatment zone. Within the treatment zone, ozone reacts to substantially destroy microbial populations. Additionally, the concentration of ozone is reduced in the treatment zone to less than 1, preferably substantially less than 0.1 ppm of ozone in the aqueous stream.

METHOD OF TREATMENT In the process of the invention the aqueous stream which is directed to the treatment zone can be obtained from any portion substantially of the slide system having an aqueous stream with a test soil charge. Preferably, the aqueous stream does not contain the entire product. The aqueous stream is preferably derived after the product is removed from the aqueous stream during recycling to a production site. The water with soil can be obtained from the water transport zone of a slide system in such a way that the product is not removed from this slide system for transport to the treatment area. Recycling water can be diverted from a recycling line to the treatment area after the food product has been removed. Water in temporary storage tanks or overflow tanks containing a substantial land load can be diverted to the treatment treatment zone. Such water materials can be obtained from cooling systems or equipment, storage tanks, sedimentation chambers, bulk cleaning, etc. The basic requirements of the system is that the aqueous stream contains some test soil charge. The presence of the ground charge allows the operators to have contact with the aqueous stream with ozone that results in the substantial death of microorganisms and the reduction of the concentration of ozone in the treatment zone before the aqueous current leaves the zone. of treatment for refusal. The amount of ozone added to the treatment zone can be easily calculated from the test soil charge concentration. However, the proportions of test soil loading and preferred concentration of ozone are discussed below.

OZONE Ozone can not be stored or shipped easily. Ozone is typically generated in situ and is dissolved in aqueous medium in the place of use just before being used. The half-life of ozone in neutral solutions is approximately 3-10 minutes and less as the pH increases. Weak ozone concentrations can be generated using ultraviolet radiation. The typical production of ozone is made using electric corona discharge. The process involves obtaining a source of oxygen in a pure form of 02 generally atmospheric oxygen (or enriched air) containing more than about 21% by volume of oxygen. The source of oxygen is passed between electrodes through which an alternating potential of high voltage is maintained. The potential is established through electrodes which are configured to avoid tonnage. As the oxygen molecules enter the potential area, a corona is created that has a proportion of free atomic oxygens dissociated from an oxygen molecule (O2). The high energy atomic ion (O) when combined with oxygen (O2) forms a mixture of oxygen and ozone (O3). These generators are commercially available. The aqueous oxygen-containing mixture is generally contacted with an aqueous solution by bubbling or other gas dispersion techniques to introduce an antimicrobial concentration of ozone to the aqueous medium. The contact between ozone and the aqueous medium is then manipulated to maximize the absorption of ozone when compared to the decomposition rate of ozone in the alkaline aqueous medium and the required concentration of ozone in the water.

The ozone activity in the aqueous medium of the invention can be improved by introducing ozone in the formation of bubbles of the smallest possible diameter. The small bubbles promote the dissolution of ozone in the bulk aqueous solution. Additionally, active surface agents that decrease the liquid gas interfacial tension can be used to increase the transport of ozone gas to the aqueous medium. The rapid dissolution of ozone can reduce the tendency to gasification into the atmosphere, and causes reactions with the components of the solution to produce oxidized species and promote the effective use of ozone. Ozonated solutions may contain ozone in increasing proportions as temperatures decrease. Aqueous solutions at 60 ° C are rapidly depleted in ozone by gasification. In sharp contrast, aqueous medium at 0 ° C may contain a fairly constant proportion of ozone of about 35 ppm. The ozone stability in aqueous solutions decreases as alkalinity increases. The half-life of ozone in 1 N sodium hydroxide is less than 10 seconds. For the purpose of the invention involving ozone concentrations in aqueous solution, the term "total ozone" refers to the amount of ozone added to the aqueous phase from the gas phase. Typically these total ozone levels in the gas phase vary from about 1 to about 1000 parts of ozone per one million parts of the total aqueous phase. The ozone measured is the apparent concentration of ozone (as O3) in aqueous solution. The difference between total ozone and ozone measured refers to the amount of ozone that apparently becomes stored in aqueous solution by reaction with organic and inorganic species to form ozonated or oxidized materials that can be a source of oxidizing potential.

AUXILIARY The ozone process of the invention is designed to operate efficiently to reduce microbial populations without the use of other antimicrobial materials. However, certain auxiliaries that have little or no antimicrobial efficacy alone can be used in combination with ozone to increase the effectiveness of ozone.

The antimicrobial composition of the invention can also comprise any number of auxiliaries. Specifically, the composition of the invention may comprise stabilizing agents, wetting agents, as well as pigments or dyes between any number of constituents that could be added to the composition. Stabilizing agents can be added to the composition of the invention to stabilize aqueous ozone solutions. Chelating or sequestering agents useful generally if stabilizing agents in the invention include alkyldiaminopolylacetic acid type chelating agents such as EDTA (ethylenediamine tetrasodium tetraacetate salt), acrylic and polyacrylic acid type stabilizing agents, phosphonic acid, and phosphonate type chelating agents among others. Preferred sequestrants include phosphonic acids and phosphonate salts including 1-hydroxy-ethylene-1,1-diphosphonic acid (CH3) C (POaFh OH), amino (tri (methylene phosphonic acid)), ((CH2PO3H2) 2 ethylenediamine (tetramethylene phosphonic acid)) , 2-phosphenebutane-1, 2,4-tricarboxylic acid, as well as the alkali metal salts, ammonium salts, or alkylaryl amino salts, such as the mono, di, or tetraethanol amine salts. The stabilizing agent is used in a concentration ranging from about 0 weight percent to about 20 weight percent of the composition, preferably from 0.1 weight percent to about 10 weight percent of the composition, and more preferably from about 0.2 weight percent to 5 weight percent of the composition.

Also useful in the composition of the invention are the wetting and defoaming agents. The wetting agents function to increase the penetration activity of the antimicrobial composition of the invention. Wetting agents that can be used in the composition of the invention include any of those constituents known in the art to elevate the surface activity of the composition of the invention.

Along with these lines surfactants, and especially nonionic surfactants, may also be useful in the present invention. The nonionic surfactants which may be useful in the present invention are those comprising portions of ethylene oxide, portions of propylene oxide, as well as mixtures thereof, and portions of ethylene oxide-propylene oxide in either heretical or block. Additionally, useful in the present invention are nonionic surfactants comprising alkyl ethylene oxide compounds, alkyl propylene oxide compounds, as well as mixtures thereof, and alkyl ethylene oxide-propylene oxide compounds wherein the oxide portion Ethylene oxide of propylene is in formation either heretical or block. Further useful in the present invention are the nonionic surfactants having any mixture or combination of ethylene oxide-propylene oxide portions linked to an alkyl chain wherein the ethylene oxide and propylene oxide portions can be in any standard random or ordered and of any specific length. The nonionic surfactants useful in the present invention may also comprise random block and heretical sections of ethylene oxide, propylene oxide, or ethylene oxide-propylene oxide. Generally, the concentration of nonionic surfactant used in the invention can vary from 0 weight percent to about 5 weight percent of the composition, preferably from about 0.01 weight percent to about 2 weight percent of the composition concentrated, and more preferably from about 0.01 weight percent to about 1 weight percent of the composition. The composition used in the process of the invention may also contain additional ingredients as necessary to aid in defoaming. Generally, defoamers that can be used according to the invention include silica and silicones; acids or aliphatic esters; alcohols; sulfates or sulphonates; amines or amides; halogenated compounds such as fluorochlorohydrocarbons; vegetable oils, waxes, mineral oils as well as their sulfated derivatives, fatty acid soaps such as alkaline-earth, alkaline metal soaps; and phosphates and phosphate esters such as alkyl and alkaline diphosphates, and tributyl phosphates, among others; and its mixtures. Especially preferable are those antifoaming or defoaming agents which are of food grade quality given the application of the process of the invention. For this purpose, one of the most effective defoaming agents comprises silicones. Silicones such as dimethyl silicone, glycolpolysiloxane, methylphenol polysiloxane, trialkyl or tetralkyl silanes, hydrophobic silica defoamers and mixtures thereof can also be used in defoaming applications. Commercially available defoamers commonly include silicones such as Ardefoam® from Armor Industrial Chemical Company which is a silicone confined in an organic emulsion; Foam Kill® or Kresseo® available from Krusabie Chemical Company which are silicone and non-silicone type defoamers as well as silicone esters; and Anti-foam A® and DC-200TM from Dow Corning Corporation which are both food grade grade silicones among others. These defoamers are generally present in a concentration range from about 0 wt% to 5 wt%, preferably from about 0 wt% to 2 wt%, and more preferably from about 0 wt% to about 1% in weight. weight. The invention may also contain any number of other constituents as needed by the application, which are known to those skilled in the art and which may facilitate the activity of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS The work slide systems typically comprise a station for introducing product to a flow of transport water which transports the product from a place of production to a place of processing. The product is removed from the flow of water at the place of production, processed and sold. The transport water is then returned to escape from production for reuse.

In some greater detail, Figure 1 shows a representation of a modality of the slide apparatus using a treatment zone 1 supplied by an ozone source 3. In the operation of the slide, a product is introduced to the aqueous stream in the orifice 17. On the slip 12, the product is transported along the length of the slide from the entrance 17 to the exit 19. At the exit 19, the product is removed from the slide for further processing. When the slide operations are initiated, fill water is provided from a source of potable or service water 6 through the line 7. During operation, the level of the slide water can be maintained using diverted water from the tank 10 through the filling line 11. The water from the slide is recycled through line 18 to the input 17 of production. The water in line 18 is pumped using pump 16 through line 15 to a pump tank 14 for rejection in the slide system. The tank spill can be discarded through the discharge pipe or conduit 13. In the operation of the process of this invention, the transport water of the slide can be diverted from operations to the treatment zone from any portion of the transport water of the recycling or replenishment slide. In such treatment operations, a relatively small volume of total slurry water is typically about 20 volume percent, less than about 10 percent, preferably less than 5 percent, and as low as 1 percent or 0.5 percent in volume. Volume can be treated on a continuous basis in the treatment area. The treatment zone may be sized to contain the volume to be treated. Preferably, the process of the invention is operated in a continuous flow base where the treatment zone has a fixed volume. Alternatively, the process of the invention can be run in a charge mode by filling a cargo tank with sampled water from any portion of the slide operations. In the charge tank, the materials can be contacted with ozone for the purpose of contacting the water with a test soil charge for the purpose of reducing microbial population. Once treated and after the ozone concentration is reduced, water can be pumped from the cargo tank back to the slide apparatus, the tank replacement or any other current or volume of water in the slide operations.

In the preferred continuous flow mode of the invention, a continuous stream of slurry water containing the characteristic test soil charge flows into the treatment zone to make contact with gaseous or aqueous ozone. Figure 1 shows a line 4 with an in-line pump 20 that transports slurry water from recycle line 18 to treatment area one. Within the treatment area, the slurry water is treated with ozone. Ozone is typically generated in an ozone generator 3. Such generators are commercially available.

An ozone treatment method involves the direct injection of ozone gas, from the three ozone generator, to the treatment zone one where the gas comes into contact with the aqueous test soil charge. Treatment zone 1 may contain pumps, static mixers, or other mechanical aids to effect efficient gas contact and transport in the liquid phase. This method tends to give the highest microbial death in the load. With this method, additional water would not be supplied through line 2. Alternatively, a second method is where water is supplied through a supply line 2 and put in contact with ozone under conditions to maximize the concentration of ozone in the water . Typically drinking water at neutral pH's is commonly used at relatively low temperatures of less than 21 CC, preferably 0 ° -18.3 ° C, to maintain relatively high ozone concentrations. The ozone is brought into contact with water under mixing conditions using small ozone bubbles and high stirring rates to obtain the transfer of ozone from gas phase to aqueous phase. Ozonated water is added to slurry water in sufficient proportions to form enough ozone to reduce microbial populations in the slidewater to levels that will aid in the control of microbial growth throughout the slide system. Typically, a 2-3 log reduction in microbial levels should be achieved with this control. Preferably treated slurry water does not have the capacity to form a new colony or microbial population after treatment. However, some small proportion of microbes may continue to exist in the treated water.

Figure 2 is similar to Figure 1 except that slip water is obtained directly from the slipper unit. Slipper water containing the characteristic soil charge is obtained from the slide processing end 19. Such water is delivered via pump 20 through line 4 to the line of treatment zone 1. After the treatment has been completed, the treated slurry water is returned to the slipper at any convenient point. Again, the ozonation of the slide water 4 can be done by directly injecting ozone gas into the treatment zone 1, from the ozone generator 3, without additional water from the supply line 2; or, by ozonation of the water from the supply line 2, and this ozonated water mixed with the slurry water delivered through line 4. In Figure 2 the treated water is returned to the transport slipstream in line 5 In a continuous flow system, ozonated or ozonated water is typically introduced to the treatment zone at or near the site of the slipwater inlet of the system. The immediate and intimate contact between the slider water with its characteristic land charge and the ozone or ozonated water ensures that the volume of slick water is sufficient and suitably treated to reduce microbial populations before leaving the slipstream water in the area of treatment. Additionally, maintaining a close and deep contact between the ozone and the slick water in the treatment zone ensures that the slurry water, at the exit, has a substantially reduced ozone concentration and can be safely contacted with the equipment. , product and operative personnel. The treatment zone shall result in, or shall be configured to, agitate the slurry water and ozone mixture to ensure deep contact between all portions of the slide water, test soil charge, microbial population and ozone to ensure that the ozone is used efficiently to reduce microbial populations. As such the tank may contain static or dynamic agitation equipment to ensure full contact. As described above, the product of the ozone generator 3 is contacted either directly with the slurry water in the treatment zone or with an aqueous stream 2 to produce a stream of ozonated water which is brought into contact with the water of slide in the treatment area. In the latter method, ozonated water may contain ozone in a solution and gaseous phase. In the case that excess ozone is mixed with the aqueous stream, the ozonated stream will contain a greater amount of ozone than that which can be completely dissolved in the aqueous stream. Such ozone is transported through to the treatment zone and is combined with the slick water to result in a high ozone concentration, but effective in the treatment zone.

EXPERIMENTAL DATA Studies on microbial death were conducted using a laboratory-scale slide model designed to reproduce the conditions shown in a typical slide unit as shown in Figure 2. Laboratory tests were conducted using a bulk tank of 130 liters (slide 12), which contains 50 or 100 liters of creek water tributary, as a laboratory-scale version of the slide apparatus shown in Figure 2. The slurry water effluent was made by milling a weighed amount appropriately from vegetable material (eg, potato, tomato, pea) in a commercial blender, followed by 1-2 days of aging at room temperature so that the microbial counts increase in the vegetable puree test. This vegetable puree was added, with constant agitation, to the bulk tank containing water and agitated to produce the effluent of slurry water. This mixture was circulated through the transport line 4 on a laboratory scale to treatment zone 1 (containing the pump, static mixer, and reducer). The volume of this treatment zone 1 was approximately 0.3 liters, thus giving a treatment area ratio: volume of slurry water effluent of approximately 1 :: 167-333 (0.3-0.6% volume of continuous treatment). After the treatment zone, the slide water was returned to the slide via a transport line 5. A potential oxidation-reduction (ORP) probe was placed near the surface of the laboratory slide 12 to measure aqueous residual ozone. An ORP >value; ~ 400 mV could indicate residual aqueous ozone not consumed in the treatment zone. The tests were performed on transport water contaminated with a soil charge prepared from three different plant materials, potato Figure 3, tomato Figure 4 and pea Figure 5. The information obtained from these experiments, shown in Figures 3- 5 demonstrates the effectiveness of ozone to reduce microbial levels (standard plate count, total microbial) for solutions containing soil and suspended-soluble concentrations of potatoes, tomatoes and peas. The information shows the unexpected result that a greater reduction of 2-log can be achieved if a treatment zone is used, in water containing a test soil charge; even those containing typical levels of weights of high demand for plant matter found in commercial slipstream waters. In a well mixed tank the reduction of microbial populations can reach 100% death in a single pass through a treatment zone when the concentration of the test ground load comprising potato, tomato or pea is less than 1 % on the volume of water in the slide. The information in Figure 6 is an example of the use of various ozone addition regimes to effect microbial control. The results indicate that a small effect in the microbial reduction regime is on a four-fold ozonation regime. Apparently the microbial level of slide is more influenced by the volume of treated plant effluent than by excess ozone in the higher ozonation study where it is consumed by the plant material (within the treatment zone), and is not available for additional microbial reduction in the slide system. Again, demonstrating the effect of a treatment zone with novel ozone vs. Bulk system treatment of current art.

In addition, the information in Figures 3-5 illustrates that as the ground load (test is increased from 1% to about 6%), the amount of ozone increases non-linearly at a rate lower than the rate of increase of load of soil to obtain comparable death results. Referring to Figure 4, as the tomato test soil load is increased three times, the amount of ozone consumed to obtain a reduction greater than 3-log of microbial populations remains relatively constant In contrast to the current art that relies on a concentration of residual aqueous ozone in the slide systems for microbial control, the current method minimizes the residual ozone outside the treatment zone, and all issues related to the safety of workers, although still allowing reductions of microbes.In the current experiments an oxidation-reduction probe (ORP) was used It is available, and routinely used, in the slide tank to measure residual aqueous ozone concentrations. Figure 7 illustrates the relationship between ORP and aqueous ozone concentrations, with an exponential rise in ozone level for a linear increase in ORP. The figure demonstrates the utility of ORP to determine if residual aqueous ozone is present, as values of ~ < 400 mV's are considered negligible and values above - 800 mV significant for waste. Figure 8 compares a non-ground loading system (non-vegetable matter) treated by the current extra-time method and two of the vegetable-loaded systems followed by the reduction of microbes in Figures 3 and 5. For the non-charged system , after ozonation, the ORP value increases from ~ 300 mV (non-ozone in time 0) to > 800 mV (substantial aqueous ozone) after 10 minutes of ozonation. Conversely, when vegetable matter is present, the bulk solution slip ORP does not rise, even after 60 minutes of ozonation, above the 300 mV mark; indicating essentially no residual aqueous ozone in the slide. Therefore, demonstrating the unique principle that ozone can be consumed (by plant and microbial matter, within the treatment zone without requiring the current art of a waste to effect microbial control, and without the issues of exposure to It should be noted that an ORP measurement taken within the treatment zone (contrasted with the above-mentioned slide ORP's outside the treatment zone) rises from about 170 mV (at time = 0 without ozone present) to> 800 mV on the treatment time of 60 minutes Thus, demonstrating the concept that there is aqueous ozone in the treatment zone, but on the slide (outside the treatment zone) there is a non-comparable increase in ORP or level of treatment. ozone).

The information in Table 1 illustrates the lack of residual ozone effects for a slide pea effluent. The solution was ozonated for 2 minutes, the ozone removed, and a microbial death followed in additional time. The information shows that within the ozonation time of 2 minutes a microbial reduction of 1.35 log units of the slide was found, but with removal of the ozone source no additional residual reduction in the microbial population occurs; i.e., microbial reduction occurs only within the treatment zone while ozonation occurs, and no residual slip reduction occurs after its removal. TABLE 1 Time Bacterial counts (min) (cfu / ml) pre-ozone 0 1.8 x 104 ozonation time * 0-2 8.0 x 103 no ozone 5 12.0 x 103 no ozone 10 8.0 x 103 * The ozone was ignited in time = 0 min. , then off in time = 2 min. The discussion, examples and information above illustrate our current understanding of the invention. However, since many variations of the invention can be made without departing from the spirit and scope of the invention, the invention resides completely in the clauses attached hereto.

Claims (1)

1. CLAIMS 1. A method for controlling microbial growth in a continuously flowing aqueous system comprising an aqueous stream flowing in a closed loop from a processing site to a production site using a recycle stream to return the stream to the processing site, the current that transports an agricultural product from a place of production to a place of processing, the current having a test soil charge, the method comprising the steps of: (a) maintaining a flow, comprising a fraction of the aqueous stream , through a treatment zone that contains a volume of treatments comprising the fraction of the aqueous stream, the stream having a test load comprising a microbial population, an inorganic and an organic earth; b) contacting the flow in the treatment zone with an effective amount of ozone, sufficient to substantially reduce the microbial population in the treatment zone while reducing the ozone concentrate; and c) returning a treated volume to the aqueous stream having an ozone concentration of less than one part by weight of ozone per one million parts of the aqueous stream. 2. The method of claim 1 wherein the treatment zone is placed in the recycle stream between the processing site and the production site. 3. The method of claim 1 wherein the treatment zone may contain the fraction comprising less than about 10% by volume of the aqueous stream. 4. The method of claim 1 wherein the effective amount of ozone in the treatment volume is about 0.5 to 50 ppm. The method of claim 1 wherein the effective amount of ozone in the treatment volume is about 1 to 20 ppm. 6. The method of claim 1 wherein the treatment volume is substantially free of another antimicrobial. The method of claim 1 wherein the treatment volume comprises less than about 2% by volume of the aqueous stream. The method of claim 1 wherein the treated volume comprises about 0.1 to 0.9 volume percent of the aqueous stream. The method of claim 1 wherein the rate of flow of the aqueous stream through the treatment zone is from about 25 to 4000 liters per minute, and the volume treated is about 0.5 to 200 liters. The method of claim 1 wherein the temperature of the treatment volume in the treatment zone is approximately 5 ° C to 40 ° C. eleven . The method of claim 1 wherein the temperature of the treatment volume in the treatment zone is approximately 10 ° C to 30 ° C. 12. The method of claim 1 wherein the pH of the treatment volume is about 5.5 to 8.5. The method of claim 1 wherein the concentration of ozone in the treated volume, just before returning the treatment volume to the aqueous system, is less than about 0.5 ppm. The method of claim 1 wherein the test load comprises about 0.1 to 20% by weight of the aqueous stream. 15. The method of claim 1 wherein the test load comprises about 1 to 15% by weight of the aqueous stream. 16. The method of claim 1 wherein a reduction greater than a 3-log in the microbial population is achieved. 17. The method of claim 1 wherein a reduction greater than 3-log in the microbial population is reached. 18. The method of claim 1 wherein the ozone in the treatment volume returning to the aqueous stream has an OPP of less than about 350 mV. The method of claim 1 wherein the ozone in the treatment volume returning to the aqueous stream has an OPP of less than about 300 mV. The method of claim 1 wherein the ozone gas is brought into direct contact with the treatment volume. The method of claim 1 wherein the ozone is contacted with water to form an aqueous ozone, and the aqueous ozone is brought into contact with the treated volume.