BACKGROUND It has long been known that ozone, either in a vapor form or dissolved in water, is extremely effective in killing bacteria and mold as well as destroying organic pollutants.

Ozone has been used in sewage treatment plants to generate an effluent that can be safely discharged and in the production of potable water and to sterilize medical products prior.

Most recently there have been numerous instance reported where consumers have become sick, due to ingestion of food, such as fresh fruit, which is contaminated with bacteria or mold such as wisterias monocytogenes bacteria (commonly found in sewage and residual in some soils), Clostridium botulinum (found in soil and naturally found in decay on corn, soybeans, and grasses), and the more dangerous salmonella (found on produce as a result of bird feces and fertiliser based on animal feces) and Escherichea coli cyst bacteria"E. coli" (fertilizer and feces). Washing the produce with water containing a sufficient concentration of ozone could eliminate this risk. For example, besides produce suppliers washing their products with ozonated water as part of their normal cleaning process, produce departments in supermarkets could rinse the produce with ozonated water before putting them on display for sale and food preparation centers, such as in restaurants, could rinse fresh produce with ozone/water before preparing it for serving.

However, no system is available which can be used in such environments. Typical ozone generating systems are designed for high volume applications, such as industrial or

municipal processing plants, and cannot be used, or scaled down for use in a sink-side food sale or processing environment. Particular problems with currently available systems include: a) large, inefficient ozone generators which require large compressors for delivery of air or oxygen for conversion to ozone, b) system components (valves, tubing, seals, pumps, storage vessels, etc. ) are designed for large volume delivery systems; that destructive of ozone by the materials of construction can be tolerated because the ratio ozone in contact with the exposed area of these materials to the total quantity of ozone is small (loss of ozone due to reaction with the materials of construction is a tolerable percentage), c) a lack of a contact tank and mixing loop for proper absorption of ozone in water to reduce off gas during product dispensing and to provide a time delay for a feedback loop to control ozone concentration in a portable system, and d) the absence of user-friendly operator controls including ozone concentration indicators for use by persons with little knowledge of ozone equipment, and internal safety components to protect the operator from inadvertent overexposure to excessive ozone gas as a result of improper use or a system malfunction.

It has been discovered that the design of a system specifically for the total desired delivery volume on a per minute basis and the required ozone concentration in that quantity delivered (design output) and the capability to deliver that design output on a continuous basis in a safe and efficient manner required a completely new design approach to the satisfy the design criteria and the use of a unique combination of materials, system components, controls and safety devices, and control software. Use of a system incorporating features of the invention can replace the use or chlorine or radiation sterilizing systems.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic drawing showing the components of the dissolved ozone delivery system and their inter-relationship.

FIG. 2 is a perspective front view showing the exterior of the wheel mounted cabinet containing the system of Fig. 1.

DETAILED DESCRIPTION A dissolved ozone delivery system 10 incorporating features of the invention comprises a control module and display 12 mounted on a free standing, readily moveable or mountable enclosure 14 is shown in Fig. 2. Mounted within the enclosure are all of the components shown schematically in Figure 1 necessary to intake room air and deliver a steady stream of water containing a desired concentration of dissolved ozone. The only external attachments required are an adequate supply of water and a 120 volt (or 220 volt) power source. The system includes the following subsystems: 1) A wheel mounted cabinet to enclose and carry all of the system components, 2) A controller system, 3) An integral hose reel for delivery of the ozone containing water, 4) Alternately operable in a spray mode or recirculation mode, 5) Internal recirculation loop, 6) A destruction system to scavenge and destroy vented ozone, 7) Operable with a 120 volt, 15 amp or a 220,8 amp feed, 8) Environmental ozone detector with warning and automatic shut down controls, 9) A gauge to continuously display the ozone concentration in the recirculation loop.

10) The display uses a ready indicator as a loop lock indicator for the desired setting on the consentration loop. The operator simply starts the machine and sets the level of ozone (the unit is preset to a most common use level). when the desired level is reached +. 5 ppm, the ready indicator lights, the light

remains on until the dissolved ozone level drops to less then setting indicated on the level setting. The generator will cycle to maintain the desired level internally.

11) An oxygen concentrator, and 12) A compact, high efficiency ozone generator.

The cabinet enclosure 14 is designed to be rolled through a standard 32 inch or wider doorway. It includes a top mounted control panel 12 conveniently located for operator access and easy visibility. Rotatable and easily lockable castors (wheels) 16 are mounted to the four corners of the unit. In a typical embodiment, the cabinet is 27-32 inches wide and deep and four to five feet high with a control panel 12 mounted to the upper portion. One preferred embodiment is 27 to 28 inches wide and deep, about 54 inches high and has a control panel 12 mounted at the top of and at an angle of about 45° to the front face of the cabinet.

In a preferred embodiment a PLC controlled system uses a custom controller card specifically designed to operate and integrate the operation of the various components.

The front panel 12 includes all of the control switches, indicators, and audio alert systems 18 necessary for operation of the system and to vary the desired ozone delivery stream, preferably sealed so that any water which may spill on the unit will not penetrate into the and disable the electronic controls. The control switches, which are in the control panel 12, are preferably provided as a membrane keypad. All system indications are provided with both visual and audio feedback. For example when a button is pushed, a beep sounds and a visible LED change will occur. Operational failures will result in a coded tone sequence, the tone being varied for each type of failure. This will not change even though the language on the membrane key pad may be changed for use in different countries. The read outs are connected to high and low pressure sensors, sensors to indicate the concentration of ozone in the intake air and the output water stream, RS232 input ports 20 so that the controller software can be modified, updated, and supplemented, audio 18 and visual 22 alerts to warn of malfunctioning or variations from set points (component malfunction, excess or low ozone, high or low pressure, low

system flow, plugged filters or dirty screens, malfunctioning parts), switches to turn on or off various components (valves, water pump, ozone generator, oxygen concentrator) component diagnostics to evaluate proper functioning, etc. While the control panel 12 and each of the components monitored and controlled by the switches are schematically shown in Figure 1, the control connections between these components is not shown so as not to complicate Fig. 1. One skilled in the art will be readily able to connect these various components.

The hose 24 designed for the system is a key component of the system. It was found, because of the reactive nature of most available hose materials to ozone, that, even though the concentration of ozone in the water stream exiting the ozone generator may have been more than adequate, the concentration of ozone in the water exiting the delivery hose was extremely depleted. In prior art systems, large diameter hoses and pipes are used to deliver the ozone containing water. Because large volumes of ozone containing water were delivered, the percent of water in contact with the delivery hose wall was relatively small and the loss of ozone along the length of the hose may have been limited to about 25%. However, when small quantities are to be delivered, smaller diameter hoses are used and the ratio of wall contact area to volume of ozone water passing there through greatly increases so that ozone loss, as a result of contact with'an ozone reactive hose material, was 90% or greater. This is totally unacceptable. It was discovered that a suitable hose 24 consists of an internal lining composed of convoluted pure PTFE with a polypropylene overbraid to maintain the bend radius required for assembly and the pressure of operation. Teflon was substantially non-reactive with the ozone in the water so that a 15 foot hose 24 with spray nozzle 26 could be used and the ozone concentration in the water delivered 28 at a flow rate of 3. 5GPM per minute had an ozone concentration, at the delivery end, of at least about 90% of the concentration of the water exiting the ozone/water mixing tank (delivery concentration-up to about 14ppm).

When operated in the delivery mode the system takes water from a feed source delivering the water at 15 to 100 psi. In recirculation mode intake 28 water is feed from a tank, trough or sink 30 so that ozonated water used for treating produce can be recovered and recirculated for reuse to conserve ozone and reduce the amount of ozone dissipated into the operating area. Alternatively, a standard water supply 32 can be used. In this case, the pressure of the incoming water is preferentially limited, by a valve 32 to 10 psi.

An internal recirculation loop 34 is provided so that during on-and-off delivery of the ozone water to a treatment area, the ozonated water is recycled through the system and an internal mixing loop 36 and storage and mixing tank 38, the tank preferably holding about 6 gallons to maintain the desired ozone concentration and reduce the time the oxygen generator 40 and ozone generator 42 have to operate to provide the desired concentration level. More specifically, one or more sensors 44 in the recirculation loop 34 monitor the ozone concentration and provide modulating signals to the ozone generator 42 oxygen concentrator 40 and feed control valve 41 reducing the output of these components until the ozone level falls below a preset control point. This also allows the system 10 to operate in an instant-on mode so that when it is desired to deliver ozonated water, the water has the preset, controlled concentration of ozone.

In learning the various causes for the destruction of ozone in order to select inert system materials of destruction, methods to rapidly destroy ozone were also elucidated.

This knowledge allowed the development of an ozone destruction device 46 which is positioned to receive any ozone vented from the system, more particularly vented from the mixing tank. The ozone destruction system 46 comprises a proprietary combination of pellets made of various metal catalysts sold under the trademark CARULITE 200 by Carus Chemical Company, Peru, Illinois. In a preferred embodiment the metal catalyst pellets are placed in a tube 46 at the air intake 48 to the oxygen generator 40 with the tube being heated by the exhaust hot air 50 released from the oxygen concentrator. This keeps the CARULITE material from absorbing water and becoming inactivated. While the catalytic destruction of ozone is exothermic once started, if the catalyst material becomes saturated with moisture, the reaction will not start.

On the other hand, in order to minimize the reactive. destruction of ozone circulating in the system, and thus preserve as much of the ozone generated as possible, all components that come in contact with gaseous or dissolved ozone are fabricated from Teflon, stainless steel or chlorinated polyvinyl chloride (CPVC). 316 stainless steel is the preferred grade. However, a broad range of stainless steels appear to be useable and generally non-destructive to ozone. Typical materials of construction used in prior ozone delivery systems which were found to be particularly destructive to ozone, and thus reduce the amount and concentration of ozone in the solution delivered include various rubbers, including silicone rubber, various metals which are normally subject to oxidation such as standard steels, which tend to rapidly rust, aluminum, which forms an aluminum oxide coating and copper, which rapidly oxidizes. These materials not only rapidly destroy the ozone, they also rapidly become oxidize and degrade so they contaminate the water solution, loose strength, leak (such as seals) or disintegrate (such as pump impellers).

While ozone very effectively destroys bacteria, mold and organic materials that may be hazardous to the users health, excess exposure to ozone by equipment operators can also be detrimental to health. Acceptable exposure levels to ozone depend on the length of exposure time. The odor threshold is 0.01 to 0.04ppm, at 0.05 to 0.1 ppm minor irritation to lungs and throat occurs, 0. lOppm generally causes headache, and from about 0.25 to 0. 5ppm a temporary reduction in lung function may occur. At 0.8 to lppm inflammatory tissue reaction can occur and lung irritation and coughing results; at exposure levels from 1.5 to 9ppm increased lung irritation and fluids build up in the lung occurs, with symptoms lasting up to two weeks. Exposure to lppm for 6-10 hours can cause chromosome damage in humans and considerable irreparable damage occurs at 10 to 50ppm, l lppm continuous exposure for 15 min can cause unconsciousness and 50ppm continuous exposure for 30 min. is generally fatal.

Recognized workplace limits established by OSHA are O. lppm for 8 hours, with no more than 0.3ppm exposure continuously for 10 min. Accordingly, the system is designed to shut down if ozone concentrations at the sampling site, which is also at the air

intake 48, reach 0.3ppm. While this is a preferred setting, the alarm and shut down setting can be established based on the operational environment. For example, the alarm and shut off point may be set higher when operating in areas where high levels of atmospheric ozone are present.

The system includes a sensor 52 that continuously monitors the ozone in the intake air stream. This location is preferred because it minimizes damage from spray water or erroneous readings due to heat generated by components of the system or hydrocarbons which may be released as off gases. This ozone level in the intake air stream can be correlated with the ozone concentration in the air being inhaled by the system operator. The system includes three alarm levels. When intake air ozone concentrations exceeds a preset lower threshold level a periodic audible and visible (flashing light) alarm 12,18, 22 is activated. When a second higher preset level is reached a higher pitched or more persistent audible and a more readily visible alarm is activated. If the operator continues to operate the system and the ozone concentration in the intake air continues to rise so that it exceeds an upper preset limit a distinctive audible alarm 18 sounds, along with other possible visible alarms, and after a preset time (preferably 1 second) the ozone generator system automatically shuts down and can not be restarted until the ambient ozone concentration is reduced to a safe level. The preferred system settings are currently set as follows: Low ozone alert-0. 14ppm-Low frequency beep alert 50ms once a second and fault and ventilation indicator light appears on the control panel.

Medium ozone alert-0. lSppm-Medium frequency beep 50ms once a second + fault and ventilation indicator light appears on the control panel High ozone alert-0.23ppm-High frequency beep 50 ms once a second + fault and ventilation light appears on the control panel System shut down-0.26ppm-System stops all functions, fault and ventilation error lights stay lit until operator presses power off and restarts machine.

Alternatively, or in addition, other alarms may be included and meters or gauges may be provided on the control panel 12 to show the ozone levels being detected by the inlet air sensor 52.

While there are various ozone detectors or sensors available, a particularly suitable device for alarm purposes is the ECO Sensor Model FM-1 available from Lenntech Water-& Luchtbeh. Holding b. v. of Delft, The Netherlands. This sensor is calibrated to 100ppb = 1000mv output, requires 5v and ground input, and has a usefully detection range of 30ppb to 300ppm. This device uses a heated metal oxide sensor (HMOS). It measures the electrical resistance of the intake gas stream and correlates it to ozone concentration. While the sensor resistance varies approximately linearly with ozone concentration, this device is not specific to ozone as it will detect a change in electrical resistance caused by any abnormal constituents in the air such as other oxidizing gases (chlorine, nitrogen dioxide, urine residues, sulfur and ammonia compounds, and acid gases (nitric and sulfuric) ). Also, it is flow dependent, therefore a relatively constant air flow between 200 and 1000 ml/min is desired. However, in the typical operating environments contemplated, a resistance detector is adequate for the purposes intended.

The theoretical maximum solubility of ozone in room temperature city water'is 22ppm. The steady state operation of the system is capable of continuously delivering 6 gallons per minute of water with a dissolved ozone concentration of from about 10 ppm to about 14 ppm (about 4% by weight). The concentration of ozone in the recirculation loop is monitored using a polarographic sensor 44 which is ozone specific. A preferred 44 sensor is a series 313xx sensor available from Orbisphere Laboratories of Neuchatel, Switerzland. This sensor is capable of accurately and continuously measuring ozone concentrations from 5ppb to lOppm. Applicant modified this off-the-shelf sensor by removing the two circuit cards from an existing unit and feeding the signal output into the system controller. With the circuitry provided, 0.05 to 5vdc output was calibrated to a tolerance band and +-0. lppm accuracy so that it provides readings from lppm to lOppm 0.25ppm.. Actual ozone concentrations, indicated in ppm ozone, can then be displayed

on a nieter mounted in the display panel 12 or used by the CPU to activate a"ready" LED, indicated a desired, preset concentration was reached.

While various ozone generators can be used in the system, the preferred ozone generator 42 is an air cooled unit capable of generating a high concentration of ozone at 3. 5gpm, with 4 to 18 % w output. The flow is limited to 8 scfh by a venturi. The preferred ozone generator is described and claimed in US Patent Application, Serial Number 09/793,795, filed Feb 23,2001, incorporated herein by reference. The device described therein is a small size, high voltage, high efficiency ozone generator. A preferred embodiment comprises a) an enclosure including an entry chamber for receiving feed gas, such as air from a dryer, an oxygen concentrator on oxygen supply such as from a liquid oxygen source, or other enhanced oxygen feed sources b) one or more ozone generating cells comprising interleaved electrodes and dielectrics with passageways between the dielectrics for receiving gas from the entry chamber and converting the oxygen therein to ozone, c) an alternating voltage generator connected to the electrodes so as to create corona discharges between adjacent dielectrics, and d) an exit chamber at the other end of enclosure for receiving the ozone containing gas.

A first typical ozone generating cell includes a first electrode, a second electrode, and first and second dielectrics. The first electrode includes a top face. The first dielectric includes a top and bottom face. The bottom face is opposed to the top face of the first electrode and separated therefrom so as to form a first passageway. The second electrode includes a bottom face opposed to the top face of the first dielectric and separated therefrom so as to form a second passageway. The received gas flows through the passageways. The top face of the first electrode may include a plurality of crests and troughs relative to the bottom face of the dielectric oriented across the flow of received gas through the first passageway. The bottom face of the second electrode may also include a plurality of crests and troughs relative to the top face of the dielectric and mirroring said crests and troughs of the top face of the first electrodes. The passageways between the crests and the dielectric will typically have a uniform gap or spacing.

A second ozone generating cell comprises two opposed electrodes with first and second dielectric layers adhesively attached respectively to the opposed faces of the electrodes. The unattached faces of the first and second dielectric films are spaced apart and provide a flow space for feed oxygen to be exposed to a corona discharge emanating from the dielectric films.

When powered, each dielectric provides a plurality of points of corona discharges on its unattached sides. The received gas must flow through substantially a continuous curtain of corona discharge. The turbulent flow is also created by the device construction, an increased gas flow rate and turbulence resulting from the corona heating of the feed gas in contact with the cooler dielectric films This cell design also eliminates the requirements for a corrosion resistant construction materials, such as stainless steel heat sink surfaces for corrosion resistance against nitric acid by-products created when air is used as a feed gas for ozone generators.

Figure 1 is a schematic diagram showing the major components of a system incorporating features of the invention. The inputs to the system are room air 48 and city water (or recovered ozonated water) 28.

In order to produce ozone a gaseous stream containing oxygen must be fed to the ozone generator. The source can be bottled air or oxygen or ambient air. In the embodiment shown the oxygen containing feed gas is ambient (room) air 48 that is drawn in by a compressor 54 and then fed to an oxygen concentrator. Several different devices to concentrate oxygen are commercially available, including membrane systems and resin based (zeolite molecular sieves) systems. A preferred device is a Work Horse 8 provided by SeQual Technologies of San Diego, CA. This oxygen concentrator 40 is capable of generating 8 standard cubic feet per hour of a gaseous stream containing 90% oxygen at 15-20 psi. When this oxygen enriched stream is feed to the above described ozone generator 42, a gaseous stream 56 containing 4% by weight at 5scfh (13gr/hr) of ozone is produced. This ozone containing gas stream 56 is then aspirated into a stream of water

58 which is flowing at about 3 to about 5 gallons per minute, and at a pressure of from about 15 to about 30 psi, preferably 20psi. While the internal diameter of the tubing in the water recirculation loop 34 depends on the amount of ozone containing water to be delivered, a typical tubing used in the system is 0. 030" Teflon (0.750 inch i. d. ). The water now containing ozone passes through a mixing loop 36 made of 25ft of 0. 75" 304 convoluted stainless steel to cause turbulence and good mixing and fed into a mixing tank 38. The mixed stream of water exits the bottom of the mixing tank 38 where it reenters the recirculation loop 34 and is alternatively directed to the delivery hose 24 or through the recirculation loop 34 and back to the ozone injection point 58, mixing loop 36 and mixing tank 38. It has also been found that when the spray mode is activated, temporarily removing the throttling valve 62, which is important for maintaining the pressure on the water stream in recirculation mode, improves the ozone delivery at the nozzle 26. This is accomplished by opening the bypass loop 90 when the spray mode is activated.

The mixing tank 38 is designed to create a clockwise flow, to create a time delay of about 3 minutes for diffusion and then provide to the recirculation loop 34, and to the spray head 26 on demand, a consistent dissolved ozone source. On the top of the mixing tank 38 is a water/air separator 92 to vent undissolved ozone. This undissolved ozone may then be fed via feed line 94 back to the ozone generator and then mixed into the water stream. When the spray head 26 is not spraying, the system 10 goes into internal recirculation mode. It is important to prevent system overpressure during recirculation to keep the ozone output concentration consistent when operated in burst spray mode.

Included in the recirculation loop 34 are typical flow control and drain valves 60, vents and pressure relief valves 62, pumps 74, pressure and flow controllers or regulators, particulate filters and strainers 66,68, high and low pressure sensors 70,72 and at least one ozone sensor 44 (described above). Control of the pressure in the system has found to be an important variable as it has been discovered that if an excess pressure is generated in the loop (greater than about 20psi) then the dissolved 03 will be rapidly released as ozone gas as the ozone containing water exits the spray nozzle 26 and become

a air pollutant. A spray nozzle 26 constructed of plastic and stainless steel has been found to be relatively non-destructive to the dissolved ozone. The nozzle water delivery openings are sized so that, at the generally used water delivery rate, the water is delivered in a sprinkling manner rather than a forceful spray. This minimizes back pressure and minimizes the loss of dissolved ozone as a result of expansion through the nozzle. In other words, the spray nozzle 26 is designed to deliver the dissolved ozone with only a minimal pressure difference (over pressure) between atmospheric pressure and the pressure of the water in the recirculation system. This requires the utilization of both constant flow controller (s) and constant back pressure valve/regulator (s) 60,62, 64.

Besides the components described above, the embodiment shown in Figure 1 includes: a % z hp pump 74 with a flow capacity of 3. 8gpm at 40psi delta, a 5 micron bag filter 66 constructed from a 304 stainless steel mesh, a 100 micron 304 stainless steel mesh Y-strainer 68, and high and low pressure sensors 70,72 set at 5-lOpsi and 40-7psi, respectively.

A typical 5p filter 66 comprises a stainless steel vessel with up to 2 liters capacity holding a basket about 3 inches in diameter and 9 to 15 inches long. The basket is constructed of three coaxially nested screens with a progressively smaller pore size in the direction of flow, the smallest pore size being 51l. While the filter is rated for flow of about 10gpm, the flow through the filter is generally limited to about 3.5 gpm. However, the system can be set to sound an alarm if flow approaches a predetermined set point, for example 2. 5gpm, and to shut down the system and flash a visual alert if the preset minimum flow rate falls below about 2. 5gpm.

The system also includes a water supply line 32 with a pressure regulator 64 so that input water pressure is maintained in the range of 10 to 20 psi. The incoming water feed is also modulated to prevent the mixing tank 38 from overfilling. Limiting the pressure on the feed water also assures that pressure at the ozone injector is minimized, reducing total gas intake and ozone gas loss at the spray nozzle.

While the system described is intended for use as a produce washer, one skilled in the art will recognize that its use is not limited to that application. The dissolved ozone

delivery system described herein and incorporating features of the invention can be used in any applications where it is desirable to provide a consistent, continuous, controllable quantity of dissolved ozone over an extended period of time. A particularly suitable application is the decontamination of a broad variety of surfaces which may have been exposed to harmful organic or biological materials such as chemical or biological warfare agents, for example, anthrax, sarin, etc. Liquid ozone can neutralize almost every known biological and chemical weapon. The above described system for generating dissolved ozone provides a suitable delivery system for liquid ozone (dissolved ozone) for washing contaminated surfaces. Also, while water is described as the liquid in which the ozone is dissolved, one skilled in the art will recognize that the same system can be used to dissolve ozone in any suitable liquid, including water containing other additives for cleaning, decontamination or preservation purposes.

Although particular embodiments of the invention have been illustrated and described, various changes may be made in the form, composition, construction, and arrangement of the parts herein without sacrificing any of the advantages. Therefore, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense, and it is intended to cover in the appended claims such modifications as come within the true spirit and scope of the invention.