CA2258865A1

CA2258865A1 - Apparatus and methods for the disinfection of fluids

Info

Publication number: CA2258865A1
Application number: CA002258865A
Authority: CA
Inventors: Edward L. Leblanc; Jeffrey C. Burnham; Walter F. Emig, Iii
Original assignee: Individual
Current assignee: Burnham Technologies Ltd
Priority date: 1996-06-20
Filing date: 1997-06-20
Publication date: 1997-12-24
Also published as: WO1997048421A3; WO1997048421A2; US6083387A; AU3793697A

Abstract

This invention relates to apparatus and methods for the disinfection of fluids and, in particular, to the disinfection of industrial fluids with ultraviolet radiation. These fluids are typically used in manufacturing as coolants in both long and short assembly lines. They commonly accumulate contaminants from multiple and diverse sources including oil and microorganisms. Fluids can be disinfected by establishing a fluid flow rate sufficient to prevent occlusion of the walls of the ultraviolet transmissible portion by contaminants. Fluids may be so heavily contaminated so as to require removal of at least a minimum percentage of contaminants (MPC) prior to irradiation. Such fluids may be processed to remove the minimum percentage of contaminants according to the equation: MPC = 102 - (23.45 x ln V). Subject to removal of the MPC, a flow rate can be established to prevent occlusion of ultraviolet-transmissible portions of the flow path and thereby successfully treat the fluid with a disinfecting amount of ultraviolet radiation. Using these methods, microorganism levels can be greatly reduced with a reduced need for biocides or other anti-bacterial or anti-fungal agents. The methods and apparatus of the invention also comprise a flattened-tube mechanism for increased exposure to UV radiation and a turbulence-generating system to increase effectiveness of radiation treatments. Turbulence-generating systems include means for creating pressure differentials or aeration in the fluid stream as well as various types of structures such as ribbons, paddles, cones, beads or vanes that can be placed within the lumen of the tubing system. These methods are highly effective at extending the useful life of fluids such as coolants and reducing or eliminating the risks posed to workers by heavily contaminated or biocide-treated coolants.

Description

CA 022~886~ 1998-12-21 APPARATUS AND MET~IODS FOR THE
DISINFECTION OF FLUIDS
Back~round ofthe Invention 1. Field of the Invention S This invention relates to apparatus and methods for the disinfectionof fluids and, in particular, to the disinfection of opaque industrial fluids with ultraviolet radiation.

2. Description of the Background Coolant use in America's heavy industries has been a story of l 0 signific~Tlt SllccP~cPc and failures. The efficacy of coolants in prolonging the life of various tools used in manufacturing has been high. This is due, in part, to the inclusion of specific organic and surfactant compounds that lubricate the materials and minirnize oxidation damage and surface buildup of constituent substances on the tools. These compounds, as well as contaminating tramp oils that leak into the coolant from multiple sources, provide a very suitable nutrient base for microbial growth.
Coolants, as well as other industrial fluids~ have traditionally possessed a fairly short useful life and need to be replenished often or even completely replaced. Although potentially toxic biocidal chemicals can be added to inhibit microbial growth. the biocidal effect eventually fails and supplementation with further biocides becomes impractical. Consequently, useful coolant life is only slightly extended. In addition, there are considerable envhuM~ental problems associated with disposal of used coolant, due in large part to the presence of these additives and other contaminants.
Over the past 50 years, machine coolant has been disposed of by dumping in drains, sewers and rivers, causing extensive and prolonged envirû,.,..e.~lal ground pollution. In 1976, the EPA ruled that all oil-based coolants were contaminated waste and must be treated or a new way of disposal found (Public Law 94-580; October 21, 1976). To accomplish this, centrifugation or 30 filtration were considered as primary alternatives. Although filtration could remove some collL~ ~lL filters often clogged or broke requiring more overall costs than CA 022~886~ 1998-12-21 WO 97148421 PCTIUS97/11428 _ would have been incurred by simply repl~ring the coolant. In addition, a successful filtration process only prolonged the life of the coolant by about two or three weeks making overall savings minimal. Centrifugation has been the principal mechanism for removing contaminated oils in larger machine tool plants. While centrifugation S as an oil removal technique has a limited tre~tment rate, it has been used to reduce conce"L. ~tions of co"~"in~nls~ usually to about two percent. However, this partial removal does not prevent bacterial regrowth or breakdown of coolant and oil components.
Ultraviolet (W) treatment has been used to disinfect clear waters 10 and some wastewater as shown in United States patent numbers 3,634,025;

3,700,406, 3,837,800, 3,889,123, 3,894,236; 4,471,225 and 4,602,162. Each of these U.S patents describes a method touted to be designed to sterilize water-based fluids. The principal idea behind this technique was that W radiation would penetrate the clear liquid to kill offending microorg~nisrrs. The conventional 15 technology of W t~ llelll is limited because total quartz systems have a tendency to foul easily and maintenance costs were high. W treatment proved to be unsuccessful for industrial fluids such as coolants, as coolants are opaque, or substantially so, and often contain significant levels of contaminants such as hydraulic and way oils which are highly occlusive to ultraviolet light. Under these 20 constraints, ultraviolet radiation cannot pass more than a very small distance, if at all, into the fluid stream ~e.g. U.S. 3,456,107). These contaminants and coolants blocked W transmission directly and also indirectly by adhering to wall surfacesof submerged quartz W lamps or to the inner surfaces of the W tr~n.cn~issikle tubing in a dry system design, wherein W lamps are kept separated from the fluid25 being treated.
A number of measures to prevent the degradation of coolant by microorganisms have been attempted with the objective to prolong the life of thecoolant and to reduce odors and health risks associated with coolant spoilage. To "~l,.i,.,.ze these risks and the hazards of contaminated coolant fluids, many facilities 30 add appreciable levels of various biocides to coolant fluids to kill and inhibit the CA 022~886~ 1998-12-21 growthofmicroor~an~ s(~.g. U.S.3,230~137). Ingeneral,coolantsperform properly in the presence of these additives. However, allergic reactions to the biocides were common. In many cases, the biocides interacted with the skin of workers and caused various forms of hypersensitivity and dermatitis. In short, 5 although bacterial counts can be reduced over the short terrn, biocides were often more problematic than the microorganisms themselves. Ultimately, the microorganisms overcome the biocides and the microbial degradation of coolant and contarninants results in foul odors in the work envirol~"ent.
Conventional techniques, although usefi~l in the short term, do not l 0 provide long term reduction of rnicrobial counts in large industrial systems by more than a single log and, more importantly, only prolong coolant life for a short period desplte their high cost. Other techniques such as aeration of coolant and thorough cleaning of the lines and machines through which the coolant flows proved to be largely uncllccescful in maintaining low levels of bacterial populations. Bacteria 15 regrow in this en~,;,ur,ll,clll due to the presence of available nutrients, and overcome inhibitory factors introduced by aeration or chemical management. Ultimately, the bacteria take hold throughout the coolant system.
Other, newer methods for the disinfection of coolant include pasteurization. ln this process, coolant is heated to a pasteurizing temperature for 20 a required period of time and subsequently cooled to an operating temperature.
This process is energy intensive and the costs, resulting from the heating and cooling steps, are high. Although attempts have been made to keep pasteurizationtemperatures below the critical temperature that would destroy or denature the coolant, constant te""~,e.dlure cycling negatively effects coolant components.
25 Consequently, thae is a strong need for a safe and environment~lly friendly method - for the disinfection of industrial and other fluids.

., _ CA 022~886~ 1998-12-21 WO 97148421 PCTIUS9'~/11428 Summary ofthe Invention The present invention overcomes the problems and disadvantages associated with current strategies and designs and provides new apparatus and methods for the disinfection of fluids.
S One embodiment of the invention is directed to methods for disinfecting a fluid. The method comprises exposing the fluid to ultraviolet radiation a~er removing at least a minimum percentage of contaminants (MPC) necessaly to permit effective disinfection according to the equation: MPC = 102 -(23.45 x InV), wherein V is the flow rate of the fluid being exposed to ultraviolet radiation. The method is useful for the treatment of opaque and substantially opa4ue fluids such as industrial fluids including coolants, machine fluids, bath fluids, process fluids and washing solutions.
Another embodiment of the invention is directed to methods for disinfecting a cont~min~ted fluid in a flow path. Fluid is pumped through the portion of the flow path exposed to a disinfecting amount of ultraviolet radiation at a rate sufficient to prevent adhesion of contaminants to W transmissible surfaces within that portion.
Another embodiment of the invention is directed to methods for d,~ g a contaminated fluid in a flow path. These methods comprise passing the fluid through a portion of the flow path and generating turbulence within that portion. Turbulent fluid is exposed to a disinfecting amount of ultraviolet radiation.
Turbulence can be generated by pumping pressurized fluids such as a gas or a liquid through the flow path. Alternatively, turbulence can be generated by piacing obstacles within the flow path Such obstacles include ribbon, beads, cones, vanes and combinations of these structures.
Another embodiment of the invention is directed to apparatus for disinfecting an industrial fluid. The apparatus is comprised of a tubing system for guiding the passage ofthe industrial fluid at a flow rate (V) through the apparatus.
The tubing system conlplises an ultraviolet-transmissible portion having a flattened to rounded cross section. The apparatus further comprises a contaminant , CA 022~886~ 1998-12-21 wo 97148421 PcT/us97111428 separation system for removing at least a minimum percentage of con~anlinants fron~ the fluid according to the equation: MPC = 102 - (23.45 x InV). The contaminated fluid is then exposed to an ultraviolet radiation system. The ultraviolet radiation system comprises a plurality of ultraviolet lamps and, 5 optionally, reflectors to direct W radiation in close proximity to the fluid flow as a dry modular apparatus.
Another embodiment of the invention is directed to apparatus for disin~e.;~ g an industrial fluid. The apparatus comprises a tubing system for guiding the industrial fluid through the apparatus at a flow rate (V) through the apparatus.
10 The tubing system is comprised of ultraviolet-transmissible tubing having a flattened to rounded cross section. The apparatus further comprises a turbulence-generating system for creating turbulence with a Reynolds number or turbulence characteristic above that defining laminar flow, within the fluid during irradiation. Turbulence generating means include techniques such as placing intra-tubular paddles, beads, 15 cones or vanes within the tubing, or creating a pressure differential or aeration within the tubing. Turbulence moves target microorganisms from W-free zones within the interior of the tube to the surface of the fluid at the tube where they are killed upon exposure to UV radiation. Turbulence also serves as a scouring forceto prevent contaminants from adhering to tube and/or lamp surfaces. Turbulent 20 ~uid is than irradiated from ultraviolet radiation system comprised of a plurality of ultraviolet lamps in close plox"luly to the fluid. The apparatus may further contain a contaminant separation system for removing at least a minimum percentage of contaminants from the fluid accolding to the equation: MPC = 102 - (23.45 x InV).
Another embodiment of the invention is directed to fluids disinfected 25 by the methods and apparatus of the invention. Such fluids include beverages and industrial liquids such as coolants and other lubricants.
Other embodirnents and advantages of the invention are set forth in part in the description which follows, and in part, will be obvious from this description, or may be learned from the practice of the invention.

CA 022~886~ 1998-12-21 WO 97/48421 PCT/US97~11428 Description of the Drawin~s Figure I Concept of a dry modular W disinfection system.
Figure 2 Reflector designs for optimizing W reflection (A) in a single direction and (B) in nearly 360~ of reflection.
5 Figure 3 Tube within a tube turbulence-generating mechanism.
Figure 4 (A) Single bead and (B) beads on a string turbulence-generating mesh~nicms. (C) Cross-sectional view of a W transrnissible tube.
Figure 5 The LOZC filtration and gerrnicidal system.
Figure 6 Bacteriocidal effectiveness during W treatment at 10 gallons per I O minute.
Figure 7 Bacteriocidal effectiveness during UV treatment at 40 gallons per minute.
Figure 8 Expression for percent of oil removat for UV effectiveness as a function of percent maximum fluid velocity in the system and viscosity of the oil.
Figure 9 Expression of degree of oil removal as a function of fluid velocity.

Description of the Invention As embodied and broadly described herein, the present invention is directed to apparatus and methods for the disinfection of fluids with ultraviolet 20 radiation.
In an industrial setting, metal particles and way oils heavily co,~ fn~ate coolants in ass~.llbly and manufacturing lines. In a packing plant. fruit juices and so~ drinks become contaminated with microorganisms such as bacteria and yeast or other types of fungi. Other contaminants enter the fluid as it proceeds 2~ through various mixing and bottling systems. These and other contaminants serve as an abundant nutrient base in which microorganisms flourish.
Conventional methods for the disinfection of fluids include ,.,t:,-,~,ane filtration to remove microorganisms or pasteurization or the addition of chemicals, antibiotics or other additives to kill and/or inhibit proliferating .. .. .. .

CA 022~886~ 1998-12-21 microorganisms in the fluid. These methods, although useful in the short terrn, provide few long term benefits and pose serious problems of their own Filtration, usually effective for controllable flows of water, is usually impractical for the disinfection of industrial fluids. These fluids contain significant amounts of oil and 5 debris as contaminants. Such fluids include metal-working fluids and other machine-tool lubricants and coolants. These fluids contain components essential to their function that would be filtered out along with any unwanted contaminants or would require multiple filtration steps and filter changes, making the filtration process impractical. Adding chemicals presents health risks to workers, as well as 10 to the environment, and can reduce coolant efficiency Repeated pasteurization can denature the molecular structure of components of the fluid, thereby reducing coolant efficacy. Methods such as exposure to W radiation, useful for W
transparent fluids, have proven to be ineffective for non-W transparent (opaque)fluids with oil and other contaminants.
It has been discovered that microbially contaminated fluid can be disinfected by ultraviolet radiation when the flow of fluid through the disinfection step is above a set rate. In this manner, microbial contamination of fluids, such as UV-opaque and industrial fluids. can be substantially reduced or elimin~ted by treating the fluid with ultraviolet radiation. Substantially reduced means that 20 microbial contamination is reduced such that useful life of the coolant is extended or the concentration of biocide needed to prevent microbial growth is lowered.
Above a set critical level of contaminants, a minimum percentage of contaminants(MPC) can be removed from the fluid before the disinfecting properties of W
radiation can be successfully administered. MPC is a variable which is dependant25 on the velocity ofthe fluid as it proceeds through the radiation treatment. The more rapid the rate of fluid flow, the less the amount of contaminants that need to be removed. The lower the flow rate, the greater the amount of contaminants that must be removed. As flow rate can be controlled, the MPC can be determined for most any fluid.

CA 022~886~ 1998-12-21 One embodiment of the invention is directed to a method for the disinfection of a fluid with an ultraviolet radiation treatment system. A successful process is dependent on maintaining at least a minimum flow of fluid in the system.
This flow rate is required, in part, to prevent occlusion that interferes with the ll~hsnf.ssion of W energy to the microorganisms. lnterference can be in the formof occlusion on the inner walls of the tubing of a dry disinfection system or the outer walls of quartzj~ckçted ultraviolet lamps in a submerged disinfection system.
In some cases it may not be possible or desirable to achieve nuid flow rates high enough to prevent occlusion. In these cases~ occlusion can be controlled by removing at least a minimum percentage of contaminants from the fluid. That MPC can be represented by the function of the equation: MPC = 102 -(23 .45 x InV); wherein V is the velocity or flow rate of the fluid in the system, i. ~
the fluid subjected to ultraviolet radiation Once the MPC has been removed, a desired fluid flow rate can be established that allows for successful treatment with a disinfecting amount of ultraviolet radiation. For example, for fluids treated at a flow rate of about 5 gallons per minute (GPM) in a 3/4" diameter tube, MPC
removal should be at least about 50% (102 - (23.45 x In5) = 50%). For a fluid treated at a flow rate of about 40 GPM, h~IPC removal should be at least about 2.5% ~10'' - (23.45 x ln40) = 2.5%). Flow rates are typically from less than about I to about 150 GPM or more, and preferably from about 10 to about 60 GPM.
However, as fluid flow rates are controllable, the disinfection process can be tailored to the working parameters of most any configuration of machines. Using this simple forrnula, fluid disinfection by ultraviolet radiation can be successfully predicted and accomplished at almost any flow rate.
The principal contaminants in a contaminated fluid such as, for example, an industrial fluid, are heavy oils including way oils. Although solid particles may be present, MPC is a volume percentage, not a weight percentage and particle removal is not considered in the calculation. Consequently, MPC is a c~'c~ tion of the volume of oil that must be removed from the fluid for succes.cful disinfection by ultraviolet radiation in a flowing system. Nevertheless, with many CA 022~886~ 1998-12-21 WO g7/48421 PCTfUS97/11428 types of fluids, particle removal may be required as there can be a synergistic effect of certain metallic particles with heavy oils that rapidly leads to W occlusion of most any surface. ln such cases only when both heavy oils and metallic particles are removed can occlusion be prevented and radiation treatment be successful.
S Many contarnin~tin~ oils have differing viscosities that can be significantly different from the viscosity of the uncontaminated fluid being treated.
This viscosity difference can be taken into account when calcul~ting MPC or minimum flow rate (MFR). Way oils tend to be fairly viscous with viscosity measurement of between about 160 to about 1 150 Saybolt SUS at 1 00~F. Cutting oils and pretreating oils have a lesser viscosity of from about 41 to about 199 Saybolt SUS at 1 00~F. Hydraulic oils are of middle viscosity of from about 63 to about 147 Saybolt SUS at 1 00~F. The effect of increasing viscosity of contaminant oil from a mean viscosity of 275 Saybolt SUS at 100~F for medium viscosity contaminant oils, such as hydraulic oils, to a mean of 665 Saybolt SUS at 1 00~F for heav~ co~ ",--ant oils such as way oils, is to increase the requirement for removal of contaminant oils be about 10%. In a similar fashion, when the viscosity decreases to a mean light oil level of 120 Saybolt SUS at 1 00~F, the amount of oil to be removed decreases by about 10%.
Fluids that can be disinfected according to the invention include. for example, liquids such as water and flavored water, carbonated beverages and other ~uids under pressure, flavored drinks, fruit juices, soR drinks, beers, wines, liquors and industrial fluids. Industrial fluids are fluids typically used in assembly lines and other m~nllfacturing configurations, to cool, clean and lubricate as appropriate to the specific operation being perfor~ned Typical industrial fluids accumulate about 1% to 7% hydrophobic hydrocarbon contan inants, with the remainder of contaminants being silicon oils and soluble lubricants, all usually in an aqueous medium (e.g. water). However, non-aqueous fluids, such as electro-discharge machine fluid (EDM), can also be successfully disinfected by the practice of this invention Preferably, fluids to be disinfected are substantially opaque.

._ .

CA 022~886~ 1998-12-21 ' 10 Substantially opaque fluids are fluids that do not allow lethal ultraviolet radiation energy to pass more than about I . 5 mm into the fluid.
In large factories, rn~nllf~chlring lines can be quite long and contain huge volumes of fluid such as in the manufacture of automobiles, aircraft and 5 automobile and aircraft parts. These lines comprise one or a plurality of machines in series (i.e. a workin~ line), a fluid reservoir or tank, a piumbing system intercormecting the various machines and often a fluid sump with a pumping mechanism. The sizes of the tubes that ~uide the flow of the fluids in such system vary tremendously depending on the location in the system ranging from small to 10 large. Smaller tubes may have a diameter of greater than about 4 mrn, greater than about 6 rnrn, or greater than about 10 rnrn or more. Larger tube sizes, greater than two inches, greater than three inches and even greater than four inches, are typical in most industrial settings. As the invention is not limited by the ability of Wradiation to penetrate a fluid, most all fluids used in industrial systems can be treated 15 according to the methods of the invention.
Specific types of fluids typically found within these manufacturing ines include metal-working fluids, machine-tool coolants, machine-tool lubricants, electro-discharge machine fluid, Zyglo~ electro-coating fluid, chassis-washing fluid~
top-coating fluids, sonic-bath fluids, spot- and steam-welding coolants, electron-20 beam and laser-welding coolants, test-cell waters for metal processing, plastic molding and forming coolants, quenching fluids, recycled and recirculation fluids, and combinations thereof.
In the di~ reclion of fluids, one or more prefilters or particle filters are typically used to remove heavy particles such as metallic or plastic chips and 25 filings. With industrial coolants, this step removes metallic particles which, in combination with way oils, lead to sludge formation and subsequent occlusion of UV transmissible tubing or W lamps in the system. Prefilters are preferably comprised of metal or plastic strainers that remove the larger and coarser particles present in the fluid (e.g. metallic or plastic particles, chips and shavings). Additional 30 filters that can be used include composite fiber-mesh filters and the like. Mesh CA 022~886~ 1998-12-21 filters contain fibers of, for example, polyester, polypropylene, nylon, Teflon,Nomex, Viscose or combinations of these materials. These fibers have a wide variety of pore sizes (e.g. 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 7~, l00, 125, 150, 175, 200, 300, 400, 500 micron) and are comrnercially available.
Once larger particles have been removed, fluid flows to a second stage filter such as, for example, a coalescent filter to remove additional con~ . Coalescent filters contain fibers, structured with various pore sizes, that are adherent to the contaminant. Coalescent filters are commercially available that are adherent, for example, to the heavy way and hydraulic oils, such as tramp oils, common in industrial fluids. For industrial fluids, the combination of a particle filter and a separator~ such as an oil separator, removes sufficient amounts of contaminant particles and oils present in the coolant to allow for successful disinfection with ultraviolet radiation. An important advantage of this combination is that both live and dead bacteria are removed from the fluid which thereby reduces l 5 the requirement for the ultraviolet system to conduct all of the killing and at the same time. As dead bacteria are an important nutrient source for bacterial growth, removal of dead microbes is an important and previously unrecognized advantage.
In this embodiment ofthe invention, fluid flows from the separation system to the disinfection system. After establishing a fluid flow rate sufficient to scour the ultraviolet lamps or W transmissible tubing and, if necessary, removing excess conlanfil.aLing oiJs, fluid is d;~i"r~led by treatment with ultraviolet radiation.
Radiation may be applied from ultraviolet lamps submerged within the fluid or kept separated from the fluid. Sub,l,elged lamps generally require protection from the fluid such as a quartz jacket or coating that allows for a high transfer of W
2S radiation while preventing damage to the W lamps. Preferably, the disinfection system is a dry system where the W lamps are placed in close proximity to, but not within the fluid. This allows for easy W lamp replacement and heat generated from the W larnps can be disseminated without d~m~ging the fluid. A dry system requires infrequent maintenance, a real advantage for this design. In one embodiment of the invention, ultraviolet treatment is applied at Breater than about CA 022~886~ 1998-12-21 12,00() microwatt seconds per cm2 of radiation, p-e~-~bly greater than about 20,000 microwatt seconds per cm7, and more prefe-~bly greater than about 40,000 microwatt seconds per cm2. In the absence of a mini-num amount of contaminants, as determined by flow speeds, fluid can be succ~ssfillly exposed to the Icilling effects 5 of ultraviolet radiation.
The invention possess many advantages. As ultraviolet radiation neither adds to nor detracts anything from the fluid, the process has no effect on the integrity of the fluid. A need for chemicals such as gerrnicides and biocides, presently used in the disinfectant of fluids, is greatly reduced or completely 10 eliminated. As biocides are themselves expensivc and pose serious health risks to workers, the savings can be considerable. In addition, many chemicals are detrimental to the efficiency and integrity of the fluid. Con.cequently, use of the methods and apparatus ofthe invention greatly extends the useful life and/or shelf-life of the fluid. In addition, odors from contaminated fluid and some biocides can 15 be fairly unpleasant. Use of the invention also reduces or eliminates such odors providing an improved air quality and working environment.
Using the process and apparatus of the invention, bacteria counts acceptable to federal (e.~. EPA or FDA), state or local regulations and various other health fields can be set for a particular fluid. This process allows for the 20 possibility of multiple passes with resident time in the W system of exposure for seconds or ~in~tes. For ~ Ie, in one test using industrial fluid, a bacteria count before coolant was processed through the oil separator and UV unit was approximately 103 to 106 rnicroorganisms per ml. After a 24 hour cycle, the microor~nicms count was almost zero. With this process, costs for the disposal 25 of co"~ a~ed coolants and for coolant replacement are substantially reduced. In addition, chemical pollution to the environ",cnt is minirnized or can be avoidedwhere processes are available for recycling used fluids. In addition, microbial counts following UV t~ ~Ll"ellL of su~lA~ ly opaque fluids can be further reduced by introducing turbulence to the fluid flow path thereby bringing bacteria to the 30 fluid surface for greater killing exposure.

CA 022~886~ 1998-12-21 WO 97/48421 PCI'/US97111428 The methods and apparatus of the invention can be used in both closed and open systems. In closed systems, such as both large and small scale assembly lines and other nl~mlf~ ring lines, fluids such as coolants flow down the line to cool and lubricate machine tools. Coolants are heat transfer mediums or 5 thermofors and may be in liquid or a gaseous forrn having the property of absorbing heat from the environment and transferring that heat effectively away from the source. As such, coolants are used in the transportation industry, the tool manufacture industry and in most eve~ small to large manufacturing plant.
Coolants, as do most industrial fluids, come in a variety of colors such as gray, red, 0 yellow, white, ereen and blue, and may be fairly thick in composition as compared to plain water. Types of coolants include propylene and ethylene glycol and Dowtherm. In addition, some coolants are anti-freezes such as, for example, propylene glycol.
In the assembly and manufacturing lines, coolants pick up a 15 substantial amount of contaminants. Substantial means that the level of contaminants are increased so as to shorten the normal usefi~l life of the fluid due to their concen~ ion and interference with coolant function and to the presence of an enhanced em~-,o~ for microbial growth Particles such as metallic or plastic filings or iron or steel chips, typically accumulate on and in the machines being 20 cooled Particles such as microolg~s~ insects, insect parts and other debris also collect in the reservoir and in the lines. These particles are all swept-up in the fluid flow. Other contaminants include lubricating oils, pretreating oils, hydraulic fluids and way oils. Lubricating oils have a low viscosity and, compared to way oils which are quite viscous, and fairly thin (~.e. heavy oils and oils with long carbon 25 chains). Tramp oils (i.~. renegade contaminant oil that gets into machine operations), typically considered a type of way oil also accumulate in the fluid, as well as water which accumulates from condensation in the lines. These contaminant substances are sticky, adhere to the walls of pipes and the W system components,and further encourage microbial growth, especially bacterial growth in the line and 30 in the ~uid reservoir. Such subst~nces also bind bacteria to their molecular interface .. . ..

CA 022~886~ 1998-12-21 surfaces. Preferably, these bacteria are removed during a phvsical separation step thereby reducing the requirement of the ultraviolet to be the sole bacterial control mechanism.
In the disinfection process, coolant is subjected to filtration by 5 passing the coolant through a prefilter to remove larger particles and debris. The prefiltered fluid is passed through a first stage filter that removes finer particulate matter. Such filters remove particles of greater than about 100 microns, preferably greater than about 50 microns, more preferably greater than about 25 microns andstill more preferably greater than about 10 microns Other contaminants~ such as 10 way and other tramp oils are removed using one or more oil separators which are~
preferably, dedicated to the removal of such contaminants.
Many techni4ues for the removal of oil from a continuous or running strearn of fluid are well-known to those of ordinary skill in the art. For example, at least rnost of the oil can be removed from a fluid by passing the fluid through a 15 plurality of oil separators. Preferable, one of such oil separators is a coalescent filter. Coalescent filters comprise fibers with predefined pore sizes wherein the fibers are adherent to the contaminants. Such filters are commercially available(U.F. Strainrite, Inc; Lewiston ME). Other oil separators useful according to the methods ofthe invention include oil skimmers and density centrifuges. Preferably, 20 the pretreatl"ent steps include a strainer step to remove particles of greater than about 100 microns, a centrifugation step to remove a large portion of the heavy oil contaminants, a prefilter step to remove contaminants of greater than about 25 microns, and a coalescent filter for removal of oil and small contaminants.
Once less than a specified level of contaminants has been reached, 25 the contarninant-reduced fluid can be successfully irr~rli~tinF with a disinfecting amount of ultraviolet radiation such that any contanli,latlls that remain do notinterfere with disinfection of the coolant. The disinfecting amount of radiationdepends on the flow rate and volume of the fluid being treated at any one moment.
For most applications, radiation is administered at from at least about 15,000 30 microwatt secondslcm' or more, depen-lulg also on the type of ultraviolet lamps, the CA 022~886~ 1998-12-21 ultraviolet transrnissibility of the tubing, the orientation of lamps around the fluid-filled tubes and the structure of the tubing (e.g. flat verses rounded). As the UV
lamps can be separated from the fluid, the method is preferably a dry disinfecting system. Although generally not required or nece~c~ry, it is also possible to sterilize 5 a fluid by increasing the amount of ultraviolet radiation administered. Ordinarily, though, sterilization is not required to maintain a safe and workable cooling system.
The oil separator and the ultraviolet radiation generating system can be designed as modular units to further increase convenience and to reduce overall costs. As such, the system can be operated continuously, subject to periodic 10 maintenance for W lamp changes or removal of accumulated contaminants, for a period of greater than one week, greater that one month, greater than one year or even longer.
All types of conventional radiation treatment can be administered to the contaminant-reduced fluid including treatment methods described in United 15 States patent 4,798,702, for use of corrugated ultraviolet-transmissible tubing, United States patent number 4,971,687 and 4,968,891, for use of thin films, United States patent number 5,494,585 for use of a cavitation process, and United States patent numbers 3,527,940 and 4,766,312, for maximizing radiation treatment by passing ~uids through a helical path. In addition, such radiation can include ionizing 20 radiation such as gamrna radiation or x-rays in place of ultraviolet. Thin films may be shaped by the structure of a portion of the ultraviolet transmissible tube. The fluid may be guided into a thin film with a thickness of less than about 5 mm, preferably less than about 4 mm, and more preferably less than about 2 mm. As radiation of substantially opaque fluids can disinfect about 1 mm to about 1.5 mm 25 of fluid, radiation transmitted from all sides of a 2 mm to 3 mrn fluid flow can be disinfected. Where complete sterilization of the fluid is desired, thin films may be useful. A wide variety of ultraviolet sterilization devices or self-contained units can be used with one or a plurality of ultraviolet lamps both within, between and surrounding the tubing.

CA 022~886~ 1998-12-21 wo 97148421 PCT/Us97/11428 Tubing and thus fluid exposure to the radiation can be optimized by creating an orientation pattern of W lamps around the tubing with ultraviolet reflective surfaces directing the radiation toward the fluid (Figure 1). Radiation exposure is highest at the fluid-surface interface. Disinfection units placed within 5 containers can ~e coated on the interior surfaces of housing 101 ~vith reflective substances. One or more W larnps 103 and reflectors 102 can be positioned so as to ~ ~e exposure ofthe fluid in tube 104 to the available radiation. Reflectors can be coated with an ultraviolet reflective material such as, for example, an aluminum, a titanium or titanium nitrate based ma~erial~ or a combination thereof.
10 Preferably, the reflector is coated by a sputtering process whereby the coating material is deposited in a vacuum onto a solid support such as an aluminum or teflon surface. In addition, W lamps may be partially coated with UV reflector substances or W blocking substances to direct energy output and/or prevent exposure of other surfaces to W radiation. Two types of reflection techniques are 15 shown in Figure 2. In Figure 2~ reflectors 201 and 202 are position in close proximity to UV lamp 207. The reflector of Figure 2A comprises W and heat ,e~ u.l plastic reflector 203 to which is applied an aluminum coating by sputtering and retainer bump 204 at each end of the reflector which serves to fix the reflector to the W lamp. According to these designs, ultraviolet reflections 205 and 206 can 20 be maximally directed to the fluid.
Many types of reflectors are known to those of ordinary skill incl~ldin~ polished aluminum reflectors, described in United States patent number 4,534,282, reflectors mounted to the frame, described in United States patent number 3,634,025, elongated curved reflectors, described in United States patent25 number 4,766,~21 and outward reflecting reflectors.
As known to those of ordinary skill in the art, ultraviolet radiation can be directed to kill eukaryotic cells, bacterial cells, fungi and spores, virus particles and almost any living microorganism. Based on the intensity of the radiation treatment, one of ordinary skill can choose to disinfect or completely30 steriiize the fluid. Sterilization is usuatly unnecessary for industrial fluids, but is . . .

CA 022~886~ 1998-12-21 WO 97/48421 PCl'JUS97/11428 oRen required to meet EPA or FDA guidelines for products regulated by gove~ l-ent guidelines such as pharmaceuticals and animal products.
Industrial fluids, for example, typically contain between about 105 to about 109 bacterial per ml Reduction of bacterial levels to at or less than about 5 103 iS generally required to provide a safe and risk-free working environment as well as to extend coolant life. Treatment of contaminated fluid, according to the methods of the invention, kills greater than 90% of the microorganisms in the contaminated fluid~ preferably greater than 95%, and more preferably greater than 99%. This reduces the bacterial load of the fluid at least about one log, preferably 10 at least about 2 logs, more preferably at least about 3 logs. Increased disinfection is pc>ssible to decrease the bacterial load ofthe fluid at least about 4 logs, preferably at least about 5 logs, and more preferably at least about 6 logs or more when necessary. Treatment times vary depending on the volume of fluid being treated and the amount of contamination and the rate of fluid flow. Therefore, treatment15 may be performed, for example, in a continuous system operated for months, weeks, days or hours to reduce the bacterial load to desired levels and to maintain such levels.
Another embodiment of the invention is directed to a method for disinfecting a contaminated fluid flowing through a tubing system. According to ~0 this method, at least a minimllrn flow rate (MFR) is established that prevents occlusion of the inner surfaces of the tubing and, preferably, those portions of the tubing that are W ~ .n,s~;~le. As the fluid passes through the W transmissible portions, the fluid is irradiated with a disinfecting amount of ultraviolet radiation.
The minimum flow rate can be c~lcnl~ted from the level of cont~min~nts in the 25 cont~inated fluid according to the equation: M~R = e((102~Pc)/23 45) he i PC
is the percentage of conta-,unanls in the contaminated fluid. Preferably, co.,l~. inants included in the calculation of PC are those contaminants which are in a liquid state and not solids such as particulate matter. For example, a contaminated industrial fluid will typically contain a variable percentage of contaminating oil and 30 an amount of solid particles. Only the volume percentage of oil would be used to CA 022~886~ 1998-12-21 WO 97148421 PCI'/US97111428 determine the value for PC. From this value, the minimum flow rate that would prevent: occlusion can be determined However, as the percentage of contaminants in the colln~ ed fluid can be ~dj~lste~, the flow rate needed to prevent occlusion can also be ~djusted. This would be useful in those instances wherein the level of 5 contaminants would be so high so as to require a flow rate that would be impractical for the particular system. In such cases, some percentage of the co,lla-, il~arlls can be removed and the flow rate reduced according to the equation.
Upon removal of sufficient contaminating oil, a workable flow rate can be established.
Another embodiment of the invention is directed to a method for disinfecting a fluid comprising establishing a turbulence in a fluid stream during irradiation. As ultraviolet radiation cannot pass more than about 1 mm to about 2 mrn into most opaque fluids, it is important to maximize exposure of the microorganisms in the fluid to ultraviolet radiation. As fluid travels transversely as 15 in a turbulent or non-laminar manner to fluid flow in the tubing, there is a greater likelihood that the microorganisms in the fluid will be subjected to ultraviolettreatment. Turbulence should be sufficient to provide a Reynolds number greater than that defining a laminar flow or greater than about 4~000. By encouraging microorganisms to move transversely, microbes are brou~ht to the surface of the 20 fiuid at the inner surface of W~ sm.s~;ble tubing 104 and not hidden within mid-sections of the tube. Passage of fluid and microorganisms within the fluid are moved from zones of no or low W radiation to surface zones of high UV
radiation. In this manner not only is killing effect magnified, but the turbulence creates a scouring effect within the tubing. Radiation can also induce oxidation of 25 certain chemicals that may be present in the fluid which may add to both the scouring and killing effects.
Tube sizes that guide the flow of turbulent fluid are not limited by the ability of W radiation to penetrate the fluid. Tube diameters which can be utilized for this method may have a diameter of greater than about 4 mm, preferably 30 greater than about 6 mm, and more preferably greater than about 10 mm or more.

CA 022~886~ 1998-12-21 Tube sizes of greater than two inches, greater than three inches and even greater than four inches, typical in most industrial settings, are also applicable to this method.
Turbulence-generating systems that encourage transverse motion S include aeration systems that create gaseous bubbles within the tube. As shown in ~igure 3, air pump 301 pumps air into inner tube 302 which contains a large number of smalJ holes 303. These holes allow the pressurized gas to escape from tube and generate fluid turbulence, transverse to fluid flow direction 304, within the lumen of the tube 305. Preferably, the gas does not interact with the fluid components.
10 Typical gasses that can be used for most fluids include, for example, air~ carbon dioxide, oxygerL hydrogen heliun~ nitrogen, argon and combinations of gasses, any of which may be pressurized In addition, this technique is not limited to gas.
Liquids may be forced into the inner tube as well creating turbulence in the fluid as the li~uid exits holes within the inner tubing walls. Liquids which can be used 15 include the liquid itself, which may be the contaminated liquid or liquid that has been treated according to the invention, an inert 1i4uid or another liquid that does not negatively interact with the fluid being treated. The tube within a tube conf;guration preferably has a controllab]e pressure differential within the tubing.
Turbulence can also be generated by suspending articles within the 20 fluid stream such as, for example, ridges, helical vanes, impellers, baffles,projections, vanes, paddles, wheels, beads, cones or slotted cones, or almost any geol,-ell ic structure. Such structures or turbulators or agitators may be on a string, free in the fùid or free, but confned in a section of the tubing. As shown in Figures 4A and 4B, bead 401 can be attached to string 402, which may be constructed of 25 a metal such as steel or a composite polyrner, and is shown both longitudinally and in cross-section. The beaded string is placed into the lumen of a tube along thedirection of fluid flow As fluid impacts the bead, fluid is directed transversely or turbulently to the sides of the tube where ultraviolet radiation exposure is maximized. As shown in Figure 4, bead 401 is slightly smaller than the lumen of the 30 tube. However, a variety of sizes may be utilized the only requirement being that CA 022~886~ 1998-12-21 WO 97148421 PCT/US97tll428 they fit within the lumen and not cause an impractical or high head pressure in the system. Combinations of these techniques may also be utilized.
Another embodiment of the invention is directed to combinations of fluid disinfection ll eatmc"ts such as those described above. Fluids may be treated with a c.o."b,nalion of contaminant removal and turbulence generation followed by radiation treatments. Such treatments may be further supplemented with conventional treatments such as, for example, filtration, centrifugation and theaddition of biocides including anti-bacterial and anti-fungal agents. However, as the cou~billalion is highly effective, the arnount of biocidal agents that are added can be 10 greatly reduced as compared to conventional methods. The working environment would be improved due, in part, to the lack of noxious fi~mes caused by microbe-induced decaying fluid, and the lack of biocides and/or microorganisms, greatly improving air quality. ~ealth risks to workers are also greatly reduced.
Another embodiment of the invention is directed to an apparatus for 1~ disinfecting an industrial fluid. The apparatus comprises a tubing system, anultraviolet radiation-treatment system, a turbulence-generating system and/or a contaminant-separation system which, for example, may be specific for particles,microbes, oil or a combination of these contaminants.
In a dry modular apparatus, the tubing system guides the passage of 20 the industrial fluid a~ a determinable flow rate through the apparatus with the W
lamps separated from the fluid. Tubing of the system is composed of ultraviolet-transmissible material such as, for exarnple, a fluoropolymer, as described in United States patent number 4,798,702. Tubing which is useful for the tubing system should preferably be capable of ~i~ pressures of greater than about 70 psi,25 and ~ bly greater than 150 psi, have a thickness of between about 20 to about 80, and more ylt:îeJ~bly 60, thousandths of an inch, and be transmissible to greater than 90~'0 of the ultraviolet radiation being applied. A preferred type of tubing has been identified and is composed oftetrafluoroethylene-perfluoro (propyl vinyl ether) copolymer or, alternatively, perfluoroalkoxy polymer (Zeus Industrial Products, 30 Inc.; Orangeburg, SC) and fluorinated ethylene propylene (FEP) (Product No. 3E

.

CA 022~886~ 1998-12-21 7S0 SW 0; Zeus Industrial Products, Inc.; Orangeburg, NC). These types of tubingare resistant to fouling, have a high corrosion resistance, are both strong and light weight, and are highly W transmissible with transmission factors of greater thanabout 95% Preferably, the tubing is flatted or oval shaped with a cross-sectional diameter ratio of about I to about 0.35, as shown in Figure 4C. Surface area exposed to W radiation is increased and the surface area of tubin~ shadowed by adjacent coils of the same spiral or by the coiled lengths of tubing is minimized. The fiatted surface may be modified to increase the wetted surface area by incorporation of longitudinal serrations~ coarse serrations or waves. These modifications increase U~/ effectiveness by increasing the area of the fluid exposed to the UV
The tubing system may also comprise one or more inlet and outlet ports attached to opposite ends of a coiled tube. The inlet ports allow for the flow of fluid from the line or the reservoir into the disinfection unit. The outlet port allows for the flow of disinfected fluid back to the line such as a manufacturing or assembly line. Tube surfaces may be smooth, furrowed, wrinkled, indented.
transverse ridged or corrugated, and the tubing may be coiled, parallel, twisted~
sel ~,e~Li~,e or in a helix at the point of radiation treatment. Ultraviolet lamps can be positioned outside and inside the tubing configuration as well as between the tubes.
Tubing has a flattened to rounded cross section (~.g. oval). However~ the system~0 may be configured to create a thin film of fluid (flattened) at the point of radiation treatment to maximize radiation exposure.
The contaminant separation system should be designed to remove particulate and other contaminants from the fluid Particulate matter can be removed with filters having pore sizes designed to remove particles of greater than 100 micron, plefel~bly greater than 50 micron, and more preferably greater than about 10 micron. The contaminant separation system contains an oil separator which is decigned to remove at least most of the oil from the fluid. Examples ofsuitable types of oil separators include skimmers, centrifuges and coalescent separators. Other unwanted liquids can be removed by a separation means ,, , _ .... .

CA 022~886~ 1998-12-21 WO 97/48421 PCTtllS97111428 particular to the type of liquid. Such separation means are known to those of ordinary skill in the art.
In addition to a contaminant separation system, the apparatus also inc.llldes an ultraviolet radiation system. The radiation system is comprised of one S or more ultraviolet lamps in close proximity to the tubing system As the lamps do not come into direct contact with the fluid, the apparatus may be described as a dry system (i.e. the lamp does not come Into direct contact with the fluid containedwithin the W-transmissible tube). In a dry system, fluid components are not subjected to unwanted heating from the UV lamps. Further~ the W lamps are not 10 cooled by circulating fluid and, therefore~ maintain a temperature high enough for optimum gellel ~lion of W radiation. Also, maintenance of lamps is minirnized due to the separation of dirty or contaminated fluid from the lamp surfaces Preferably, there are a plurality of ultraviolet larnps surrounding a coiled tube on both the inside and outside, and even between, the coils. As the energy imparted to the target fluid 15 is proportional to the square of the distance of the W lamps to the fluid, that di~t~nce should be rninirnized to maximize the amount of energy transmitted to the fluid. The unit can be ventilated or air conditioned to prevent heat build-up asnecessary to prolong the life of the UV lamps and so as not to damage the fluid.The apparatus may also contain a turbulence-generating system to 20 IllaAi~ e exposure of the fluid to the radiation. The turbulence-~enerating system should preferably be placed into the tubing wherein the fluid is exposed to the radiation. Examples of turbulence-generating systems include structures attachedto the walls of the tube or otherwise free-floating in specified areas of the lumen of the tube. Such structures include nearly any shaped article such as paddles, beads, 25 cones, vanes, ribbons and the like, any of which may be slotted, and which may be fixed to tubing walls, ~tt~ched to each other or attached to a string and suspended in the ~uid. Fixed structures may be placed at set angles to the laminar flow of the fluid, p~r~l~bly up to about 90~, such as, for example, about 20~, about 30~, about 45~, about 60~ or about 75~. Other turbulence-generating systems include tube 30 within a tube configurations that allow for a pressure di~~ ial, ultrasonic CA 022~886~ 1998-12-21 wo 97148421 PCT/us97/11428 vibrations, split-flow systems or aeration within the fluid. The apparatus may also contain circuitry applo,u,iate for proper monitoring and control of all aspects of the apparatus. The additional of computer control can also be utilized to create units that are completely or partially automated.
An example of one embodiment of the apparatus is shown in Figure 5. As shown, the apparatus is contained within housing 501 which is on casters 502 and, consequently, quite mobile. The basic unit contains pump and oil separator module 503, ultraviolet module ~04 and electronics module 50S which may contain a fan, gauges reporting on the condition of the unit and/or the status of the fluid flow~ indicator larnps and switches. W lamps 506 are positioned around a helicalportion of tubing ~07 to maximize W exposure. Reflectors 508 are positioned around W lamps 506. Fluid enters through inlet port 509, travels through oil separator 510, tubing 507 and, disinfected, exits through outlet port 511. As the unit is dry modular in design, it can be used to disinfect many different types of 1 5 fluids.
Accordi"g to one embodiment of the general process, coolant to be dis~eLled is first treated by passing through a screen to remove metallic particles and other debris. Coolant is next run through an on site commercial centrifi~ge to reduce contaminant concentrations to approximately two percent. Coolant to be ''O treated is drawn into the system by a pump mechanism. The pump forces coolant into a filter vessel under pressure which contains a filter cartridge. The cartridge will normally contain a 10 to 20 micrometer pore size which facilitates separation of the oil and binding of the oil to the fiber structure of the cartridge. Such filtration performs the important role of removing large amounts of both living and dead 2~ bacteria. Removal of the dead bacteria reduces nutrient loading in the fluid. The Lli~r~.e.~ial pressure between the input and the output of the filter vessel is used to monitor the condition of the filter cartridge and can be read at the electronic module. When the pressure reaches the specified di~ere"lial, in most cases the greatest di~wenlial, the filter cartridge has filled with contaminant oil and must be replaced. Rate of oil accumul~tion will vary depending upon the amount of oil in CA 022~886~ 1998-12-21 the coolant and the viscosity of the oil as well as the type of coolant. The fluid is forced under pressure into germicidal module 507 and disinfected before being discharged from outlet 511.
Another embodiment of the invention is directed to fluids treated S accoldil~g to the methods of the invention. Such fluids includes liquid which, after treatment, are substantially free of microbial contamination and, optionally, other co~ ,iinants as well as way and tramp oils, rnicrobial particles and other particulate materials. Substantially free means that the population level of microbes has been reduced to a level that does not pose a risk to workers, resulting in an improved quality to the working environment. Such fluids include machine tool coolants~
machine tool lubricants~ electro-discharge machine fluid, Zy~lo, electro-coatingfluid, chassis-washing fluid, top-coating fluids, sonic-bath fluids, spot- and steam-welding coolants, electron-beam and laser-welding coolants, test-cell waters formetal processing, plastic molding and forming coolants, quenching fluids, recycled and recirculation fluids and combinations thereof Other fluids including water such as potable water, water to be consumed in areas of suspected contamination, water supplies from natural or man-made emergencies, water used during military operations, third-world water supplies, livestock water and beverages such as, for example, ~avored and plain water, flavored drinks and drink blends~ vegetable, fruit and other juices, soft drinks, beer, wine and other liquors.
The follo~,ving examples illustrate embodiments of the invention, but should not be viewed as limiting the scope of the invention.

Examples Example I The Prototype Filtration/Gerrnicidal System.
A novel process has been discovered to treat coolant fluids with a colnl)iJ~alion of filtration and ultraviolet (W) light exposure. This process has the ability to disinfect both opaque and transparent industrial coolant fluids and may elimin~te or reduce the need of biocide treatn~ents for microbial control. This technology uses ultraviolet irradiation, a technique proven for the treatment of ~ . . . .

CA 022~886~ 1998-12-21 waste water effluent, which is effective against a wide range of microorganisms.The ability of the treatment to kill or control microorganisms under various operating conditions was detell,uned.
The prototype filtration and gerrnicidal system (Figure 5) comprises 5 t~vo major operational modules, a variable-speed pump and filtering module (filter unit of module is a UFI Filtration System; U.F. Strainrite, Inc., Lewiston, ME) and a germicidal module. In operation, about 15 to about 20 gallons of fluids are required to fill the filtration module, and the filtering module has a minimum capacity or flow rate of about six gallons per minute. The pump and filtering 10 module and the germicidal module are controlled from a separate control panel (the electronics module), attached to the side of the gerrnicidal module. The ultraviolet output of the germicidal module can be adjusted by changing the number of ultraviolet generating lamps utilized. For these experiments, a maximum of ~ lamps were used although the module was also capable of lower UV output settings by 15 using 2, 4, 6 or 8 lamps.

Example ~ The Prototype Test System.
Approximately 45 gallons of used coolant, consisting of coolant concentrate diluted with water at a ratio of about I part concentrate to 3.5 parts water (22% oil and 78% water) was stored in a S0-gallon drum. This mixture was 20 recycled through the L01 filtering unit and the majority of tramp oil and suspended particles were removed. After treatment, coolant in the reservoir was milky-white in color with almost unobservable tramp oil when visually inspected. Separated tramp oil was black in color. About three gallons of tramp oi] were extracted from the used coolant. Bacterial colony forming units (CFUs) were enumerated using 25 SaniCheck BF paddles (Biosan Laboratories, Inc.; Warren, MI) and the results are shown in Table 1.

. _ .

Table I
Bacterial Colony Cou lts Sample site Count (CFU) Concentration (CFU/ml) Untreated coolant reservoir lo7_1o8 2 x 108-2 x 109 Tramp oil reservoir 105 lo6 2 x 106- 2 x 10' Treated coolant before UV 52 I x 104 Treated coolant after 5 min UV 62 I x 103 Treated coolant aflcer 15 min 32 5 x 10 W
Treated coolant after 30 min 35 5 x 103 UV
Treated coolant a~er 60 min 42 5 x 103 W

Treated coolant after 120 min 36 5 x 103 UV
Treated coolant a~er 180 min 25 3 x 103 W

Treated coolant reservoir after 15 2 x 103 1 80 min W

An important step in eliminating bacterial contaminants is the filtration and separation of tramp oil. The filtration module is capable not only of separating and removing tramp oil, but also of reducing the number of rnicroorganisms present in used coolant. Tramp oil contains high concentration of dirt and contarninants.
APter 15 minlltes of treatment, a 50% reduction of bacterial count was achieved when microorganism counts obtained at the inlet-sampling port were compared to microorganism counts obtained in the outlet-sampling port The bacterial population number remained the same for next 2 hours before a further drop was observed. After this period, bacterial populations resumed their decline.

. .

CA 022~886~ 1998-12-21 WO 97/48421 PCI'/US97tll428 The drop in microbial counts continued in the coolant reservoir up to the end of the three hour experimental period.

Example 3 Testing of Model Unit L01 Usin~ a Highly-Con~a-~lina~ed Coolant.
Testing of Model L0 I was performed at BioCheck Laboratories~ Inc.
5 (Toledo Ohio). Bacterial populations were monitored using membrane-filter and direct-plating technology as per Standard Methods (~tand~rds Me~hods fo~ thL~
~valua~ion of Wa~er and Waste ~ate~ Vol. 19, published by American Public Health Assoc., 1994?, and/or SaniCheck BF paddles (Biosan Laboratories, Inc.;
Warren, MI). Trypticase soy agar (TSA! plates were used to monitor bacterial 1 0 growth.
Samples were collected from the reservoirs and sampling ports.
Bacterial counts were measured by diluting each sample tenfold with water and spreading a 50 ,ul aliquot of this dilution evenly over an I 1 cm2 surface (about 2.3 cm by about 4.8 cm). Test samples were maintained at room temperature for 48 15 hours before the results of bacterial growth were determined.
A first run was undertaken to determine the degree of bacterial survival in 25 gallons of highly contaminated used coolant during processing through the treatment unit at 10 gallons/minute (Run I). Coolant was dark green,opaque, with very little tramp oil or particulate matter. Initial inoculations of media 20 paddles indicated that the coolant had more than ]o6 CFU per ml of bacterial contamination.
Results from the temperature monitoring and from membrane filtration/plate counting analysis of the coolant are shown in Tables 2 and 3, and Figure 6. The number of bacteria cultured from the coolant in the recycling 25 rese~oir decreased over 1 00,000-fold during the 24 hour course of the treatment.
While the most effective killing rate occurred within the first hour of treatment, continued treatment was effective in further reducing culturable bacterial numbers.
Coolant was sampled and analy~ed before it returned to the reservoir The results . ~ . . _ WO 97/48421 PCT/US97tll428 indicated that approximately 90% of the bacteria in the coolant fluid were eliminated by a single passage through the coalescer filter and W chamber.
Table 2 Results of Run I
Time W Chamber Coolant (minutes) Temperature Temperature (~F) (~F) 101.7 80 210 110.5 93 9 240 111.9 96.0 360 114.3 101.8 480 115.9 105.1 540 1~70 1440 115.9 108.7 Growth on media paddles also indicated that the filtration/UV
treatment was highly effective in elirninating bacterial conl~n~ alion of used coolant. Total volume was 25 gallons with a flow rate of 10 gallons per minute at 68.5~(' (Table 3). These results were very similar to those seen with membrane filtrationJplate counting assays.
Table 3 Run 1: Bacterial Popul tion by Locatio~l Time Sarnple Total Gal. Bacteria Bacteria (Minutes) Location Treated (CFU/ml) (Paddle) 0 Reservoir 0 5.94E+07 1 E+07 Post 1 Coalescer 10 1.26E+06 2 Post W 20 8.99E+05 Reservoir 600 7.47E+05 I E+06 240 Reservoir 2400 5.56E+03 IE+05 480 Reservoir 4800 7.42E+03 I E+05 1440 Reservoir 1440 7.47E+02 IE+03 1440 Untreated 0 8.69E+06 IE+07 These results indicate that the ultraviole~ and oil separation ellt~ were very effective in eliminating bacteria in the fluid. ~rom these data~

a one hundred-fold drop was seen in the first hour. Another hundred-fold drop was observed over the next three hours. Bactericidal effectiveness continued at a reduced level between hours 4 and 8 of treatment. Finally, after 24 hours, the resulting bacterial number was reduced 100,000-fold compared to the original 5 bacterial load. Total bacterial counts of untreated coolant bacteria decreased by approximately ten-fold over the 24 hour treatment period at l l S ~F.
The next run (Run ~I), focused on bacterial survival in used coolant during cycling through the apparatus at a flow rate of 40 gallons per minute. This run was de~iEned to determine if the high level of bacterial killing observed in Run 10 I could be maintained at the maximum flow rate obtainable with the L01 unit.
Te""~e.~ure ofthe coolant in the reservoir and the t~,l,pc.~ re of the UV chamber were monitored during Run II. The temperature of the coolant increased during the course of the ~ almenl (Table 4), however, throughout the test period, temperatures remained within operating parameters of the coolant.
Table 4 Run Il: Operating Ten~P atures Over Time Time W Chamber Coolant (Minutes)TemperatureTemperature (~F) (~F) 0 69.5 69.5 3 84 70.4 93 73.8 98.8 77 120 103.g 82.9 150 105.3 86 240 108 92.3 480 111.4 101 Results from the membrane filtration/plate counting analysis of the coolant are shown in Figure 7 and Table 5. The number of bacteria cultured from the coolant in the recycling reservoir decreased approximately 50-fold during the 30 course ofthe 8 hour ll~allllenl As observed in Run 1, the most effective killing rate occurred within the first hour of treatment (Figure 6). The decrease in bactericidal .

CA 022~886~ 1998-12-21 ~ 30 effectiveness observed may he due to the initial removal of highJy suspectable organisms within the first few passes through the apparatus, followed by a process of repeated W exposure needed to kill more resistant bacteria.
Table 5 S Run U: Analysis Or Re~en~oir CFUs Time Sample Total Gal. Bacteria Bacteria (Minutes) Location Treated (CFU/rnl)(Paddle) 0 Reservoir 0 5 76E+07>IE+07 Reservoir1200 2.05E+07>IE+07 Reservoir2400 1. O9E+07I E+07 120 Reservoir4800 5.98E+06I E+06 240 Reservoir9600 1.65E+06 IE+06 480 Reservoir19200 9.29E+05 IE+05 480 Untreated 0 6.67E+07> I E+07 The number of bacterial colonies cultured on the media paddles decreased with increased treatment in the filtration~UV treatment apparatus. These numbers closely matched those obtained with the assays using membrane filtrationand culturing on TSA plates (Table 5). Results from this assay also indicated that more bacteria survived the filtration/UV treatment at a flow rate of 40 gallons per minute for 8 hours than survived in Run I at a flow rate of 10 gallons/minute aRer 8 hours treatment.
Treatment of highly contaminated industrial coolant demonstrated that the filtration/UV irradiation apparatus was highly effective in killing bacteria present in the fluid. This bacterial killing was observed in two separate runs of the apparatus. The most effective bacterial killing was observed when the unit was run at a flow rate of 10 gallons per minute, in which a 5-log decrease in culturablebacteria was observed aRer a 24-hour recycling treatment of 25 gallons of highlycontaminated coolant (10' CFU/rnl).
Thus, effectiveness ofthis appa,~lus in disinfecting opaque coolant fluid has been strongly supported in these studies. In addition, the unit ran quietly, and did not cause any overt changes in the make-up or physical behavior of the coolant fluid (e.g. foaming, discoloration, coating, e~c.).

WO 97t48421 PCTIUS97111428 Example 4 Fluid Flow Calculations.
Fluid flow velocities that prevent occlusion of ultraviolet radiation transmissible tubing have been determined from empirical testing, Increasing velocity of the fluid as a scouring force prevents occlusion as a fi~nction of viscosity 5 of the components within the fluid. Thus, the amount of oil that would need to be removed from an oil-contaminated fluid to avoid occlusion can be represented as a function of percent maximum fluid velocity in the W system at a given tube diameter (Table 6).
Table 6 Expression of Oil Removal at Set Tube Diq-neters Removal MaximumTube Diametcr in Percent Velocity(GPM) m Percent3/4~
100 1 0.5 0.84 S 2.5 4.2 15 50 10 5 8.4 l6.8 I ~ 30 15 25.2 33.6 20 5.5 60 30 50.4 4 70 35 58.8 2.5 80 40 67.2 1.4 90 45 75.6 Percentages from Table 6 were determined from the equation:
f~x) = -2.345E+1 x In(x) + 1.022E+2 (correlation coefficient R = 9.756E-I).
These numbers could be altered depending on the viscosity of the contaminant oil (Figure 8). High viscosity oils had about a 1% to 15% higher percent oil removal than medium viscosity oils. Lower viscosity oils had about a1% to 10% lower oil percent oil removal than medium viscosity oils. As can be seen, the curve reflects the percent of maximum fluid velocity obtainable. This same data was plotted on a semi-log~illu"ic scale according to the equation f(x)= -2.345E+1 x In(x) + hO22E+2 (correlation coefficient R = 9.756E-I), as shown in Figure 9. These numbers were converted with the flow equation: U.S. GPM =

WO 97/48421 PCTfUS97/11428 {ft. per sec.} x ~ID2~ x ~2.45}, to produce the actual gallons per minute (GPM) flow rate for any given tubing One inch and three quarter inch tube sizes were used as typical sizes. As the tubing becomes larger, it becomes difficult to collect the correct amount of oil to prevent occlusion and this, plus the surface requile,.,cnt for S disinfection~ may limit the practical number of gallons that may be treated effectively.
Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. All U. S patents and other documents referenced herein 10 are specifically incorporated by reference. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the invention indicated by the following claims.

. . . . ...

Claims

We Claim:

1. A method for disinfecting a contaminated fluid comprising:
a) removing at least a minimum percentage of contaminants (MPC) from the contaminated fluid according to the equation MPC = 102 - (23.45 x InV);
b) passing the contaminated fluid through an ultraviolet radiation system at a flow rate (V), and c) irradiating the contaminated fluid with a disinfecting amount of ultraviolet radiation.

2. The method of claim 1 wherein the contaminated fluid is an industrial fluid.

3. The method of claim 1 wherein the industrial fluid is selected from the groupconsisting of metal-working fluids, machine-tool coolants and lubricants, electro-discharge machine fluid, Zyglo, electro-coating fluid, chassis-washing fluid, top-coating fluids, sonic-bath fluid, spot- and steam-welding coolant, electron-beam and laser-welding coolant, test-cell waters for metal processing, plastic molding and forming coolant, quenching fluids, recycled and recirculation fluids, and combinations thereof.

4. The method of claim 1 wherein the contaminated fluid is selected from the group consisting of water, water-based drinks, fruit and vegetable juices, carbonated beverages, soft drinks, beer and wine.

5. The method of claim 1 wherein the contaminated fluid is substantially UV
opaque.

6. The method of claim 1 wherein the contaminated fluid is substantially UV
transparent.

7. The method of claim 1 wherein the contaminated fluid contains one or more contaminants selected from the group consisting of metallic particles, live bacteria, cutting oil, hydraulic oil, way oils and other tramp oils, and combinations thereof.

8. The method of claim 7 wherein the metallic particles are removed by passing the contaminated fluid through a particle filter.

9. The method of claim 8 wherein the particle filter removes particles of greater than about 10 microns in diameter.

10. The method of claim 7 wherein the oil is removed by passing the contaminated fluid through one or more oil separators.

11. The method of claim 10 wherein the one or more oil separators are selected from the group consisting of coalescent filters, skimmers centrifuges and combinations thereof

12. The method of claim 1 wherein the disinfecting amount of ultraviolet radiation comprises greater than about 12,000 microwatt seconds per cm2.

13 . The method of claim 1 further comprising the step of creating a thin film of said contaminated fluid during irradiation.

14. The method of claim 13 wherein the thin film has a depth of less than about 3 mm.

15. The method of claim 1 wherein the contaminated fluid has a bacterial load which is reduced at least 2 logs after irradiation.

16. The method of claim 15 wherein the bacterial load is between about 10 5 to 10 9 bacteria per ml.

17. The method of claim 1 wherein the contaminated fluid has a bacterial load which is reduced at least 4 logs after irradiation.

18. The method of claim 1 further comprising the step of passing the contaminated fluid through a prefilter that removes particles with a diameter ofgreater than about 25 microns.

19. The method of claim 1 further comprising the step of creating turbulence in the contaminated fluid during irradiation with a turbulence-generating system.

20. The method of claim 19 wherein the turbulence-generating system comprises a pressure differential within the fluid or aeration within the fluid.

21. The method of claim 1 further comprising the step of adjusting the MPC up to about 10% to account for a viscosity differential between uncontaminated fluid and a contaminant within said contaminated fluid.

22. A fluid disinfected by the method of claim 1.

23 . The fluid of claim 22 which is an industrial fluid.

24. A method for disinfecting a contaminated fluid in a flow path comprising:
a) pumping the contaminated fluid through a portion of the flow path at a rate sufficient to prevent adhesion of contaminants to an ultraviolet radiation transmissible surface within said portion; and b) irradiating the contaminated fluid at said portion with a disinfecting amount of ultraviolet radiation.

25 The method of claim 24 further comprising the step of removing a percentage of contaminants from the fluid prior to irradiation.

26. The method of claim 25 wherein the percentage is from about 1% to about 10%.

27. The method of claim 26 wherein the rate is from about 20 to about 50 gallons per minute.

28. The method of claim 25 wherein the percentage is from about 5% to about 50%.

29. The method of claim 28 wherein the rate is from about 5 gallons per minute to about 30 gallons per minute.

30. The method of claim 25 wherein the percentage (MPC) is calculated according to the equation: MPC = 102 - (23.45 x InV), wherein V is said rate of fluid flow in gallons per minute.

31. The method of claim 24 wherein the tubing system contains a turbulence generating system.

32. The method of claim 24 wherein the fluid flow path has a thickness of greater than about 10 mm.

33. A method for disinfecting a contaminated fluid in a tubing system comprising establishing at least a minimum flow rate sufficient to prevent occlusion of an ultraviolet-transmissible portion of said tubing system and irradiating the contaminated fluid with a disinfecting amount of ultraviolet radiation at said portion.

34. The method of claim 33 wherein the minimum flow rate (MFR) is determined by the equation: MFR=e((102-PC)/23.45); wherein PC is the percentage of contaminants in the fluid.

35. The method of claim 34 further comprising the step of adjusting the MFR
up to about 10% to account for a viscosity differential between uncontaminated fluid and a contaminant within said contaminated fluid.

36. The method of claim 33 wherein the minimum flow rate is between about 5 to 60 gallons per minute.

37. A method for disinfecting a contaminated fluid in a flow path comprising passing the contaminated fluid through a portion of said flow path, generating turbulence within the contaminated fluid and irradiating the turbulent fluid with a disinfecting amount of ultraviolet radiation at said portion.

38. The method of claim 37 wherein turbulence is generated in the contaminated fluid by a technique selected from the group consisting of placing intratubular paddles, ribbons, beads, ridges, cones or vanes within said tubing, creating a pressure differential within said tubing, creating aeration within said tubing and combinations thereof.

39. The method of claim 37 wherein the turbulent fluid is in a thin film.

40. The method of claim 37 further comprising the step of removing a minimum percentage of contaminants (MPC) from the contaminated fluid before irradiation according to the equation: MPC = 102 - (23.45 x InV); wherein V is a rate of fluid flow through said portion.

41. An apparatus for disinfecting a contaminated fluid comprising:
a tubing system for guiding the passage of the contaminated fluid at a flow rate (V) through the apparatus comprised of tubing having a flattened to rounded cross section and a portion having ultraviolet-transmissible walls;

a contaminant separation system for removing at least a minimum percentage of contaminants (MPC) from the contaminated fluid before irradiation according to the equation: MPC = 102 - (23.45 x InV), and an ultraviolet radiation system for irradiating the contaminated fluid comprised of a plurality of ultraviolet lamps in close proximity to said portion.

42. The apparatus of claim 41 wherein the portion is composed of a perfluoroalkoxy polymer.

43. The apparatus of claim 41 wherein the ultraviolet radiation system is a dry system wherein said plurality of ultraviolet lamps are not in direct contact with said fluid.

44. The apparatus of claim 41 wherein the ultraviolet radiation system comprises ultraviolet lamps submerged in said fluid.

45. The apparatus of claim 41 wherein the tubing system is comprised of an inletport and an outlet port attached to opposite ends of a coiled tube.

46. The apparatus of claim 45 wherein the plurality of ultraviolet lamps are within, between and surround said coiled tube.

47. The apparatus of claim 41 wherein the tubing system comprises a tube within a tube configuration.

48. The apparatus of claim 41 wherein the tubing system generates a thin film of the contaminated fluid during irradiation.

49. The apparatus of claim 48 wherein the thin film has a depth of between about 4 mm to about 2 mm.

50. The apparatus of claim 41 wherein the flow rate is from about 5 to about 10 gallons per minute and the contaminant separator removes at least about 80% to about 60%, respectively, of the contaminants from the contaminated fluid.

51. The apparatus of claim 41 wherein the flow rate is from about 30 to about 60 gallons per minute and the contaminant separator removes at least about 25%
to about 6%, respectively, of the contaminants from the contaminated fluid.

52. The apparatus of claim 41 wherein the ultraviolet radiation system further comprises a plurality of ultraviolet reflectors positioned to direct ultravioletradiation toward said industrial fluid.

53. The apparatus of claim 52 wherein the reflectors are coated with an ultraviolet reflective material.

54. The apparatus of claim 53 wherein the ultraviolet reflective material is selected from the group consisting of an aluminum, a titanium, a titanium nitrate or a combination thereof.

55. The apparatus of claim 41 further comprising a turbulence-generating system for creating turbulence within said industrial fluid during irradiation.

56. The apparatus of claim 55 wherein the turbulence-generating system comprises intratubular ribbons, paddles, beads, cones, vanes, or combinations thereof

57. The apparatus of claim 55 wherein the turbulence-generating system comprises a pressure differential.

58. The apparatus of claim 55 wherein the turbulence-generating system comprises aeration provided from a tube within a tube mechanism.

59. An apparatus for disinfecting a contaminated fluid comprising a tubing system for guiding the contaminated fluid through the apparatus at a flow rate (V) comprised of ultraviolet-transmissible tubing having a flattened to rounded cross section, a turbulence-generating system for creating turbulence within said contaminated fluid during irradiation.
an ultraviolet radiation system for irradiating the contaminated fluid comprised of a plurality of ultraviolet lamps in close proximity to said UV
transmissible tubing.

60. The apparatus of claim 59 wherein the turbulence-generating system comprises intratubular ribbons, paddles, beads, cones, vanes or a combination thereof.

61. The apparatus of claim 59 wherein the turbulence-generating system comprises â pressure differential or aeration within the fluid.

62. The apparatus of claim 59 further comprising a contaminant separation system for removing a minimum percentage of contaminants (MPC) from the contaminated fluid before irradiation according to the equation: MPC = 102 - (23.45 x InV).

63. The apparatus of claim 62 wherein the MPC is adjusted up to about 10% to account for a viscosity differential between uncontaminated fluid and a contaminant within said contaminated fluid