The availabiliq of inexpensive, usable water has greatly diminished over this century, and stress upon water resources is expected to increase dramatically with accelerating population and pollution. Throughout the world, industry and governments are increasingly confronted with the challenge and expense of providing modem wastewater facilities that meet public demand and enacting stringent regulatory requirements necessary to produce a cleaner environment. Globally, the need for economic, environmentally friendly industrial wastewater treatment is rapidly approaching a crisis point.

Wastewater (including industrial and municipal wastewater) frequently contains contaminants such as, e. g., microorganisms and toxic organic compounds, which may prove to be toxic in subsequent uses of the water. Examples of microorganisms frequently found in wastewater include bacteria, spores, yeasts, or fungi, algae, etc., including viruses or bacteriophages. Toxic organic compounds found in wastewater include, e. g., cancer-causing aromatic compounds and numerous halogen compounds, particularly chlorine compounds, e. g., chlorinated phenols, etc.

There are many known techniques for disinfecting wastewater, including the use of chemical or physical agents, mechanical means, and W radiation. Of these, the traditional method of disinfection has been the use of chemical agents in the form of chlorine. Although chlorine disinfection has significantly reduced the incidence of water-bome disease in the United States for many years, growing concerns about chlorine's safety and effect on the environment have prompted wastewater treatment utilities to evaluate other disinfection methods.

To date, the most viable alternative to chlorine disinfection is ultraviolet (UV) disinfection.

Chemical bonds in organic toxins can be broken under the action of the W radiation through photodissociation. A particular substance will have a characteristic photodissociation curve associated with it specifying the energies and wavelengths of W radiation for which the particular substance will undergo photodissociation : For effective photodissociation, it is necessary that the

UV radiation have the particular energy or energies which fall within the photodissociation cun-e ot the substance of interest.

With respect to microorganisms, disinfection occurs when UV ! ight contacts the microorganism's deoxyribonucleic acid (DNA) molecules, which contain the genetic information necessary for cell replication. The light causes double bonds to form between adjacent subgroups in the DNA structure, preventing normal replication of DNA molecules and thereby inactivating the microorganism.

It is also known that pulsed W flashlamps can produce a high-power output that is effective for various photodissociation applications, including the disinfection and purification of fluids.

The use of ultraviolet radiation to destroy microorganisms and/or effect photodissociation of organic compounds in wastewater is disclosed, e. g., in U. S. Patent Nos. 4,661,264 and 4,816,145 (both to Goudy, Jr.) ; 5,144,146 (Wekhof) ; 4,400,270 and 4,336,223 (both to Hillman) ; 5, 368, 826 (seltz, et al.); 4,464,336 (Hiramoto); 5,230,792 (Sauska et al.); 5,547,590 (Szabo); 5,900,211 (Dunn et al.) ; 1,670,217 (Scheidt) ; 2,338,388 (Whitrnan) ; 4,769,131 (Noll et al.) ; 5,504,335 (Maarschalkerweerd) ; 4,296,066 and 4,317,041 (both to Schenck); 5,768,853 (Bushnell et al.); 5, 597, 482 (Melyon) ; 5,322,569 (tutus et al.); 5,536,395 (Kuennen et al.) ; 5,915,161 (Adams); 5, 208,461 (Tipton); 5,364,645 (Lagunas-Solar et al.) ; 5,925,885 (Clark et al.) ; 5,503,800 (Free); 3,485,576 (McRae et al.) ; 3,814,680 (Wood) ; 3,637,342 (Veloz) ; 3,924,139; 4,103,167 and 4,767,932 (both to Ellner) ; 4,204,956 (Flatow) ; 4,471,225 (Hillman) ; 4,621,195 (Larrson) ; 4,676,896 (Norton); 4,909,931 (Bibi); 5,624,573 (Wiesman); 5,626,768 (Ressler et al.); 5,660,719 (Kurtz et al.) ; 5,725,757 (Binot) ; 5,738,780 (Markharn) ; 4,757,205 (Latel et al) ; 5,290,439 (Buchwald) ; 5,925,240 (kins, et al.) ; 4,880,512 (Comelius et al ;); 4,246,101 (Selby, IIT) ; 5,151,252 (Mass); 4,274,970 (Beitze ; 4,230,571 (Dadd); 4,304,996 (Blades) ; and 5,480,562 (Lemelson). See also Legan, R.W., Ukmviokt light Takes on CPI Role, Chemical Engineering, pp. 95-100 Qanuary 22,1982).

Another article of interest is Hanzon, B. D. and Vigilia, Rudy, just the Factf : UV Ditinjtctinn, Water Environment & Technology Magazine (November 1999), which is hereby incorporated by reference herein.

In many commercial applications, it is highly desirable to deliver W radiation to a target in a manner that simultaneously produces excellent process efficacy, economic efficiency, and the ability to do so at all times at all required fluid flow rates. Too high a LTV dosage can become an unacceptable economic burden, but an insufficient W dosage can be dangerous.

An ideal W-based water-disinfection system has a number of advantageous characterisncs.

For example, an ideal lJV-based disinfection system can provide exact application of the desired UV dosage at all times (in real time) instead of sometimes or much of the time, irregardless of the influent s UV transmission level or variances in the influent's pressure or flow rate.

Furthermore, an ideal W-based water-disinfection system further can confirm the integnty of the operational parameters. For example, the system provides active, real-time control feedback regarding the UV lamp's baseline output level and the influent's LTV transmissivity and flow rate.

The system also provides a dynamic and wide-range, real-time response for adjusting the UV light power output and influent flow rate in response to such feedback.

An ideal W disinfection system also has automatic compensative adaptability to any degradation in one or more UV reactor sections used in the system such that the system provides an active, real-time response to such degradation and assures process integrity, e. g., by not passing non- conforming effluent.

Various W disinfection systems have been developed in an attempt to provide improved control over the dose parameters. Such systems are disclosed, e. g., in U. S. Patent Nos. 4,317,041; 4,336,223; 5,144,146; 5,208,461; 5,364,645; 5,547,590; and 5,925,885. However, such conventional systems generally do not have all of the desired characteristics discussed hereinabove in connection with an ideal W disinfection system. The drawbacks to such systems can be broken down into one or more of the areas discussed below.

For example, one drawback to the conventional W disinfection systems is their use of continuos wave lamps. Most continuos wave lamps require a warm-up period prior to operation.

In addition, most continuous wave lamps are adversely affected by frequent"on-off"cycling, expenence excessive jacket fouling, and do not operate efficiently over a wide range of power output.

In another drawback, convenional W disinfecion systems use W lamps arranged in large banks that constitute a single reactor. With such arrangement of the lamps consituing a single reactor, wide and random variations in UV intensity among the individual lamps can considerably vary the dosage delivered across sections within such reactor. More importantly, accurate monitoring of each lamp's baseline output performance is impractical because every lamp would require a separate UV detector. Therefore, the UV output (and subsequently the performance) of such reactor can only be estimated via discrete probe points that do not necessarily represent anything more than a small section of the reactor. Individual lamp performance is unknown.

A further drawback to the conventional W disinfection systems is the use of passive flow control devices (e. g., weirs, gate, valves and the like) and gravity flow. As a result, the practical operating ranges of such systems work to restrict the available flow ranges of the reactors used therein. Hydraulic head losses quickly dominate the design equations, thereby limiting reactor performance range. Flow adjustments are relatively slow to execute, and a flow change in any one reactor can adversely create a flow change in adjacent reactors.

Because of the drawbacks discussed above, the conventional disinfection systems are not truly active, real-time or independent, but instead are dependent upon slower, passive techniques for monitoring and adjusting performance parameters. These systems typically exhibit large interaction dependencies among the multiple reactors that constitute an industrial-capacity system. Accurate W dosage is compromised, along with the ability of the system to adjust parameters as needed for optimized efficiency.

The needs of the water and wastewater disinfection industry for higher system efficiency and lower total cost of operation increasingly necessitates advances beyond those of conventional W disinfection systems.

Accordingly, a primary object of the present invention is to provide a reliable and cost- effective system (i. e., method and apparatus) for chemical-free decontamination of water (including wastewater).

A further object of this invention is to provide a W-based decontamination system which has the capability to instant adjust the output power of the W reactors over a wide range, thereby instant adjusting the W dosage when required.

Another object of this invention is to provide a W-based decontamination system which uses a single UV light source in each W reactor, whereby the performance of the single W light source consistently and accurately represents the performance of the entire reactor.

A still further object of this invention is to provide a W-based decontamination system wherein, in each W reactor, the baseline UV light output from the W light source can be accurately determined at any given instant, as can the actual W transmission within the reactor.

Yet another object of this invention is to provide a W-based decontamination system wherein each UV reactor is capable of controlling the influent flow rate within that reactor, can instant achieve upon command a very wide and precise range of operation, and exhibits zero hydraulic head loss, further wherein each UV reactor is capable of doing the foregoing independently of and without interaction with the other W reactors within the system.

Another object of this invention is to provide a W-based decontamination system which has monitoring and control feedback means that can provide an active, real-time response for system parametric optimization, and can do so with complete independence among the UR reactors constituting the system.

A further object of this invention is to provide a UV-based decontamination systern capable of accurate and fail-safe optimization of W dose throughout the entire range of operating conditions that are typically encountered in large-scale W photodissociation applications.

These and other objects are achieved in the present invention.

Summary of the Invention The present invention provides a UV-based decontamination system that destroys microorganisms and causes photodissociation of organic contaminants in fluids, such as water and wastewater. The decontamination system of the present invention uses variable-pulsed W light in an automatic pump-driven configuration that separately and in real-time adjusts each reactor module for both fluid flow and W power (average and peak intensity) to accommodate a wide range of varying influent conditions, thereby producing the quality of fluid discharge desired by the operator.

Process control is configured on the basis of a W transmission-based feedback control loop and on a truly active and independent adjustment of each W reactor module, as opposed to the relatively passive and dependent adjustment techniques used in many conventional W-based decontamination systems.

Specifically, the present invention provides a UV-based method and apparatus for decontaminating fluids, such as water and wastewater, contaminated with W-sensitive microorganisms and/or organic compounds.

The apparatus of this invention contains: (A) a single W reactor module or a plurality of W reactor modules, each UV reactor module being composed of : (1) an influent flow conduit; (2) a variable speed pump disposed in the influent flow conduit, the pump being rotatable at a speed determined by a pump-speed control signal; (3) a W reactor disposed in the influent flow conduit downstream of the variable speed pump, the W reactor having an interior chamber containing

(i) a reactor flow passage disposed downstream of and in fluid communication with the influent flow conduit, the reactor flow passage having an inlet and an outlet; (ii) a W\ flashlamp disposed in the reactor flow passage and capable of emitting one or more pulses of ultraviolet light having a wavelength in the W-C band, preferably from about 200 to about 300 nanometers, wherein the flashlamp emits the one or more pulses at a UV intensity and pulse duration determined by a lamp-output control signal; and (iii) at least one W transmission detector disposed at a location in the reactor flow passage so as to measure W transmissivity of a portion of a stream of the fluid passing proximate to the location, the detector being capable of generating an output signal indicative of the measured W transmissivity ; and (B) a system-wide control module disposed in independent electrical communication with each W reactor module, the system-wide control module being capable of generating the pump-speed control signal and the lamp-output control signal and of receiving the W-transmissivity output signal, the system-wide control module being programmable to generate additional pump-speed control signals and lamp-output control signals in response to the W-transmissivity signal so as to cause subsequent portions of the stream exposed to the one or more pulses of ultraviolet light to receive a targeted UV dose.

In a preferred embodiment of the apparatus of this invention, each W reactor module further contains a microprocessor-based reactor-control unit, (e. g., a programmable logic controller (PLC), a small computer, a custom-built logic board) which is disposed in electrical communication with the system-wide control module and with the variable-speed pump, the W flashlamp and the U'V transmission detector of the reactor module.

The method of this invention involves the steps of : (I) providing the above-described apparatus of this invention, wherein the control module is preprogrammed to send a first pump-speed control signal to the pump in each UV reactor module to cause the pump to rotate at a speed sufficient to provide a predetermined first flow rate through the influent flow conduit and the reactor flow passage; further wherein the control module is preprogrammed such that as a fluid stream flows

through the reactor flow passage, the control module sends a first lamp-output control signal to the W flashlamp in each UV reactor module to cause the flashlamp to emit one or more pulses of ultraviolet light at a predetermined first LJV intensity and at a predetermined pulse duration, the one or more pulses of ultraviolet light having a wavelength in the UV-C band (which is the band that effects disinfection of microorganisms and photodissociation of organic compounds), preferably from about 200 to about 300 nm; (2) directing flow of a stream of the fluid through the influent flow conduit, the stream passing through the influent flow conduit at the predetermined first flow rate; and (3) directing flow of the stream through the reactor flow passage from the inlet to the outlet thereof such that the stream passes proximate to the UV flashlamp and proximate to the W transmission detector, the stream flowing through the passage at the predetermined first flow rate; wherein during flow of the stream through the flow passage, a portion of the stream is exposed to the one or more pulses of ultraviolet light emitted by the W flashlamp in response to the first lamp-output control signal generated by the control module; the UV transmission detector measuring W transmissivity of a portion of the stream passing proximate to the detector and transmitting a W transmissivity output signal to the control module indicative of the measured UV transmissivity, wherein the control module is preprogrammed to analyze said W transmissivity signal to determine whether the portion of the stream subjected to the one or more pulses of ultraviolet light received a targeted lJV dose, further wherein if said portion of the stream did not receive the targeted W dose, the control module is preprogrammed to send 01 a second pump-speed control signal to effect a second flow rate in the influent flow conduit and the reactor flow passage, and/or (ii) a second lamp-output control signal to effect emission of one or more pulses of ultraviolet light at a second UV intensity and/or a second pulse duration; wherein the second flow rate and/or the second W intensity-and/or the second pulse duration are such subsequent portions of the stream exposed to the one or more pulses of ultraviolet light receive said targeted W dose.

The apparatus of the present invention may contain a single ut reactor module or a plurality of W reactor modules. Preferably, the apparatus contains a plurality of W reactor modules disposed in a parallel or a serial arrangement, preferably a parallel-arrangement.

The apparatus and method of this invention provide a reliable and cost-effective system for effecting chemical-free decontamination of water, wastewater and other fluids contaminated with

W-sensitive substances The system-wide control module used in the present invention separately and in real time adjusts water flow and/or UV power output in each reactor module to accommodate a wide range of varying influent conditions. Embodiments of the apparatus of this invention which use a W flashiamp disposed coaxially relative to the influent flow conduit and to the reactor flow passage further simplify the delivery of LTV light and provide a less cumbersome approach towards an accurate calculation of performance.

Brief Description of the Drawings Fig. 1 is a schematic illustration of a typical prior art W-based decontamination system for use in large-scale, high-throughput installations.

Fig. 2 is a schematic illustration of a preferred embodiment of a LTV-based fluid- decontamination system within the scope of the present invention.

Fig. 3 is a schematic detailed illustration of the W reactor module used in the system illustrated in Fig. 2.

Fig. 4 is a schematic illustration of an alternative embodiment of the W reactor module shown in Fig. 3, wherein, in the alternative embodiment, the W reactor module further includes a microprocessor-based, programmable logic controller unit. petuled Descripnon of the Invennon As stated hereinabove, the present invention provides a method and apparatus for decontaminating fluids using pulsed ultraviolet radiation. The fluids treated are those which are contaminated with W-sensitive microorganisms and organic compounds.

As used herein, the terms"decontaminate","decontaminating"and"decontamination"re fer to the ability of the method and apparatus of the present invention to destroy microorganisms and cause photodissociation of organic compounds. More particularly, the foregoing terms means that the method and apparatus are capable of killing or rendering unable to reproduce at least a substantial portion of the microorganisms present in the fluid being treated, and capable of causing photodissociation of at least a substantial portion of the organic toxic compounds present in the fluid being treated so as to form non-toxic end-products. Thus, as used herein, the term "decontaminaion"is meant to include both photodissociation and chemical disinfection.

As used herein with respect to the fluids being treated by the method and apparatus of this invention, the term"contaminated"means that the fluid contains an undesirable amount of W- sensitive microorganisms and/or organic compounds.

As used herein, the term"W-sensitive"with respect to the microorganisms and organic compounds contaminating the fluid means that microorganism will be destroyed and the organic compounds will undergo photodissociation when subjected to UV radiation.

By way of illustration, the invention will be described herein as applied to the decontamination of waste water. However, it is to be understood that the instant invention may be used to decontaminate a variety of other fluids.

The present invention uses the output spectra of pulsed UV flashlamps in various combinations of average and peak power intensity. Preferably, the pulsed flashlamps used in the present invention have a power output range of a factor of 30 or more.

The UV flashiamps used in the present invention are capable of emitting high-intensity, short-duration pulses of ultraviolet light. Pulsed, gas-filled flashlamps such as those used in the present invention produce broadband light when an electrical current pulse is discharged through the flashlamp, ionizing the gas and producing an intense burst of both continuum and line emission over a broad spectral range. Such flashlamps typically employ inert gases such as xenon or krypton because of their high efficiencies of electrical to optical energy conversion. The use of other gases or gas mixtures and gas discharge systems is possible and may be desirable for specific applications.

Suitable W flashlamps and attendant pulse-generating hardware for use in the present invention are described, for example, in U. S. Patent Nos. 4,871,559; 4,910,942; and 5, 034,235; each of which is incorporated herein in their entirety.

The W flashlamps used in the present invention are capable of emitting ultraviolet light having a wavelength in the W-C range, preferably from about 200 to about 300 nanometers (nm).

W radiation of this wavelength is particularly effective in photodisinfection because microorganisms show maximum sensitivity in this range.

Each of the high-intensity, short-duration pulses of ultraviolet light emitted by the UV flashlamp in the method of this invention preferably have an intensity of at least 0.01 Joules per square centimeter, more preferably from about 0.01 to about 50 Joules per square centimeter. Each pulse preferably has a duration of from about 0.001 to about 100 milliseconds.

The pulse repetition rate of the radiation ernissions preferably ranges from about 0.5 to about 30 Hertz.

Preferably, each flashlamp will provide a W-C output of from about 1 million to about 6 million watts of peak power per pulse.

Each UV flashlamp is preferably housed in a waterproof, protective housing such as a L*Y- transparent quartz tube. The housing (or jacket) itself is cool so that inorganic contaminants do not attach thereto.

The reactor modules can be made of a W-resistant metal such as stainless steel or other W-resistant materials.

The transportable, module-based configuration of the apparatus of this invention advantageously produces in real time an active, independent and precise pump-based flow adjustment to each UV reactor module, thereby accommodating an extremely widened range of influent conditions with minimal impact upon the infrastructure of treatment facilities. Each reactor module incorporates an integral variable-speed pump, preferably a positive displacement pump that provides an accurate indication of flow rate in real time. This allows not only a positive shut-off capability, but also a practical output range over a factor of 15 or greater. This technique is combined with the instantaneous W power adjustment of pulsed flashlamps with a power output range of a factor of 30 or more. By this method, the flow rate of any one W reactor module does not physically force a change in the flow of any other W reactor module. In an advantageous departure from the prior art, no W reactor module in the apparatus of the present invention must necessarily compromise its own performance because of the flow rate changes induced by any other UV reactor module. Therefore, all the UV reactor modules used in the apparatus of this invention are then capable of independently achieving optimum W dosage.

The monitoring and coordination of the method of this invention is provided by an intelligent control system (i. e., control module 28 in Figs. 2 and 3 or the combination of control module 28 and PLC unit 62 in Fig. 4) that calculates the optimum operating scenario for any given set of influent conditions, independent W reactor module (s) performance conditions, and the required output conditions of the effluent. The control system active) y and independently relates flow rate, UV power output, or both, in each of the W reactor modules.

Fig. 1 illustrates a typical W decontamination system of the prior art.

Fig. 1 illustrates a prior art method for decontaminating water using W radiation. In such prior art method, an influent channel or reservoir 2 is used to hold and/or move the water (not shown) to be treated. Disposed in fluid communication with reservoir 2 are a plurality of influent conduits 4. Substreams (not shown) of the water are made to flow through influent conduits 4 in the directions shown. Conduits 4 contain gravity-flow-based weirs or gate controls 6 which provide mechanical flow adjustment. From conduits 4, the influent water substreams flow in the directions

shown past banks 8 of UV flashiamps. After exposure to ultraviolet light emitted by the flashlamp banks 8, the resulting effluent substreams flow through effluent conduits 10 which also contain weirs or gate controls 6. From conduits 10, the effluent substreams flow to an effluent channel or reservoir 12, where the substreams will be available for pickup and delivery eisewhere. Flow rate sensors 16 are disposed in the influent reservoir 2, the W flashlamp banks 8 and the effluent reservoir 12. Influent reservoir 2 further has a turbidity sensor 17 disposed therein. The prior art method illustrated in Fig. 1 further uses a control system 18.

A drawback to the prior art system shown in Fig. 1 is the use of passive mechanical flow adjustment means, i. e., weirs or gate controls 6, which tend to be expensive, cumbersome, slow-to- adjust, and with limited capacity and/or adjustment. These adjustment means typically work in conjunction with spare banks of continuous wave (i. e., non-pulsed) W lamps that are either left in- line or physically removed as required. This system typically relies upon gravity flow and, as a result, are very sensitive to hydraulic pressure head loss. Despite the theoretical capabilities of such a system, the practical implementation has shown a very much restricted capacity for changes in flow rate. Any attempt to accommodate a flow adjustment in one lamp bank, channel or manifold, whether it be by an adjustment in lamp output and/or lamp temperature, W transmission, contaminant levels, or influent flow rate, can adversely affect the flow rate and W reactor performance in other branches of the system. This reactor-to-reactor dependency further limits the available range of operation. Installations that use such systems also require extensive construction of and modification to wastewater facilities, along with a lengthy design-to-startup schedule.

A simpler, quicker and more capable system is needed by industry and is provided by the present invention as illustrated in Figs. 2 and 3.

Fig. 2 shows a preferred embodiment of a decontamination method and apparatus within the scope of the present invention.

In Fig. 2, decontamination apparatus 20 includes an influent channel or reservoir 22 for holding and/or moving an influent fluid F to be decontaminated. Preferably disposed within reservoir 22 is a fluid level sensor 24, which is connected to a system-wide control module 28 composed of a stored program microprocessor. With respect to control module 28, the term "system-wide"means that the control module exerts control over all of the UV reactor modules.

Connected to a side of reservoir 22 is an influent fluid conduit 26 which directs flow of a stream Fl of the influent fluid F in the direction shown. Commands (signals) transmitted by control module 28 via control bus 30 cause fluid stream Fl to become divided into fluid substreams F2 which flow

from conduit 26 into influent flow conduits 32. Conduits 32 direct flow of substreams F2 in the direction shown into a parallel arrangement of independently adjustable UV reactor modules 34.

Note that although the W reactor modules are disposed in a parallel arrangement in Fig. 2, the UV reactor modules alternatively can be disposed in a serial arrangement.

W reactor modules 34 are independently controllable relative to one another. As will be discussed in greater detail herein with respect to Fig. 3, substreams F2 are subjected to ultraviolet rays in UV reactor modules 34 which will kill microorganisms and/or cause photodissociation of toxic organic compounds present in the substreams Once treatment of substreams F2 in LTV reactor modules 34 is complete, the resulting decontaminated substreams E2 flow out of modules 34 in the direction shown into effluent flow conduits 36. Effluent substreams E2 flow through conduits 36 into effluent fluid conduit 38, where the effluent substreams can be combined into a single effluent fluid stream E1. If desired, the effluent stream can then be transported in the direction shown to an effluent pick-up point 40 from which effluent fluid E can be picked up and delivered as desired.

Fig 3 illustrates a greater detailed view of the UV reactor module 34 used in the apparatus of Fig. 2.

As shown in Fig. 3, influent fluid substream F2 enters UV reactor module 34 in the direction shown via influent flow conduit 32. Substream F2 enters module 34 according to a flow rate established by the rotational speed of integral (i. e., built-in) variable speed pump 42. The rotational speed of pump 42 is set by control module 28 through control bus 30. Control module 28 transmits the appropriate rotational speed command (i. e., a pump-speed control signal) to pump 42 via variable-speed pump controller 44. At the flow rate established by control module 28 and executed by pump 42, substream F2 is passed through flow conduit 46 in the direction shown into an interior flow chamber 48 of UV reactor 50. Disposed within chamber 48 of UV reactor 50 is a coaxially arranged, pulsed linear flashlamp 52 which will emit pulsed ultraviolet light in response to a command (i. e., a lamp-output control signal) sent by control module 28 through control bus 30 and flashlamp driver 54. Flashlamp driver 54 contains a pulse-forming network (not shown) and a power supply (not shown). The influent substream F2 fills chamber 48 externally to flashlamp 52.

Situated at an inner wall 48a of chamber 48 is one or more W transmission detectors 56, preferably positioned in an orientation in direct line-of-sight with the flashlamp 52.

Upon command from control module 28 and by means of control/reactor interface connector 31 ; flashlamp driver 54 sends through its pulse-forming network and then into flashlamp

52 a short, high peak power pulse of electrical energy that ionizes the gas (e. g., xenon) contained within flashlamp 52 to produce a high-temperature plasma which emits a pulse of UV tight. This pulse of UV light irradiates the fluid-filled volume within the chamber 48 of UV reactor 50. Some of this light is absorbed by components in substream F2, such as suspended solids and dissolve solids. The resulting UV fluence upon UV transmission detector (s) 56 is captured by a detector interface 58 which sends a corresponding signal to control module 28 through control bus 30.

Control module 28 analyzes the signal received from detector interface 58 by means of any one of several acceptable differential measurement methods, resulting in a datum that represents the"UV transmissivity"for that particular slice (i. e., substream F2) of influent fluid encountered during that single pulse of UV light.

Meanwhile, the single pulse of W light has also irradiated a large percentage of microorganisms and/or organic compounds. Based upon (i) the volume size of chamber 48 of UV reactor 50, (ii) the known W peak power per pulse, and (iii) the known W transmission for that pulse, the control module 28 then calculates the W dose (ou) esuve/m) applied to chamber 48 during that pulse of W light. Note that this W dose is not a time-based dose rate but a discrete quantity. Comparing this single W dose to that which has been determined by the operator to be the targeted dose, control module 28 then calculates how many pulsed doses of UV light are required for a given volume of fluid at a given flow rate and proceeds to perform this in an identical process for each pulse. At any instant, the operating parameters can be adjusted as required by control module 28.

By the time substream F2 has passed through chamber 48 of W reactor 50, the substream has received the dose of W light designated by the operator and then commanded and verified by control module 28. The resulting decontaminated effluent E2 then exits chamber 48 of W reactor 50, and, as discussed above in connection with Fig. 2, enters effluent conduit 38.

A preferred embodiment of the detector interface 58 makes it possible to use in each W reactor module 34 one or more auxiliary contaminant level detectors 60 disposed to monitor indicator organisms or compounds. Preferably, a detector 60 will be disposed at an inlet (i. e., upstream) end of chamber 48 and another detector 60 will be disposed at an outlet (i. e., downstream) end of chamber 48. Such arrangement (i. e., an"influent-effluent detection arrangement") of detectors 60 is particularly advantageous in that it provides closed-loop feedback capabilities that can further increase the accuracy and efficiency of large-scale W photodissociation applications.

As stated above in connection with Fig. 2, a fluid level sensor 24 is preferably disposed within influent reservoir 22. Level sensor 24 provides fluid level rate-of-change information to control module 28 which uses this information to calculate the influent flow-rate demand by subtracting the combined flow rates of the UV reactor modules 34. At any instant, control module 28 knows the combined decontamination system flow rate because the rotational speed of the integral variable-speed pump 42 incorporated in each reactor module 34 sets the flow rate for the respective reactor module 34 and this rotational speed is set by control module 28. Data communication between the control module 28 and the reactor modules 34 takes place along control bus 30 and control/reactor interface connector 31.

With the flow rate demand established, the control module 28 has the built-in intelligence to monitor and analyze the operating conditions for each reactor module 34 and then determine the optimum control settings for each reactor module 34 that will create the net total output required for the entire decontamination system. Factors specific to reactor module 34 that contribute to this analysis include: baseline output level per pulse of the W flashlamp, filtered UV output level per pulse of the UV flashlamp, influent W transmission per pulse, W dose per pulse, pulse repetition rate, flow rate through chamber 48 of UV reactor 50, average UV dose per reactor module au c/m) and warnings, alarms and operational readiness in each reactor module 34. Factors specific to the control module 28 that contribute to the analysis include: system flow-rate demand, required UV dose for decontamination compliance OL,,-c/m), calculations and/or look-up tables for decontamination design parameters, site-specific operational criteria, decontamination system limits, wamings, alarms and readiness plan, operating and service history data storage, and extemal communications for monitor, remote operation and service.

In the apparatus of this invention, if any reactor module 34 is, at any instant, outside of established limits, the apparatus can immediately and in real time be automatically disengaged from the apparatus's output, thereby ensuring full compliance at all times. Additionally, the"zero hydraulic head loss"design of the apparatus of this invention not only presents the advantage of pressure-isolated and truly independent reactor module operation, but also the potential for the entire W decontamination apparatus to contribute essentially zero hydraulic head loss to the wastewater facility.

Fig. 4 illustrates a preferred embodiment of the W reactor module (s) used in the present invention. In this embodiment, each reactor module 34 further contains a microprocessor-based reactor-control unit 62-Reactor-control unit 62 is disposed in electrical communication with a

system-wide control module 63 and with variable-speed pump controller 44, UV fiashhmp dnver 54, and detector interface 58.

The use of reactor-control unit 62 redistributes some of the considerable microprocessor power and functionality of the system-wide control ! module. As mentioned previously, by using a reactor-control unit in each reactor module, each reactor module can perform much of its reactor- specific monitoring and calculations, thereby off-loading both the I/O control bus traffic and the time-sensitive, simultaneous multiple-reactor module-specific monitor and calculation requirements of the control system. Thus, the system-wide control module 63 used in the Fig. 4 embodiment will be one which does fewer calculations than the system-wide control module 28. used in the embodiment shown in Figs. 2 and 3. The embodiment of Fig. 4 still leaves control module 63 with overall, upper hierarchy system control. Control module 63 receives reactor performance monitor and alarm signals from each independent reactor module 34, evaluates and determines the optimum system parametric configuration, and sends to each reactor module 34 the assigned parameters which the respective reactor module 34 is to operate. The lower power microprocessor-based control unit 62 within each reactor module 34 receives from the control module 63 the parametric control signals specifically assigned to the respective reactor modules 34, calculates and sets the W dosage according to the intemally monitored data (W transmission, W output, flow-rate, and the like), monitors and adjusts accordingly, and then reports reactor output back to control module 63.

Because the UV decontamination method and apparatus of this invention are ideally suited for (but not limited to) parallel operation of the reactor modules, the apparatus can be sized to the wastewater facility's requirements by simply selecting the number of identical and transportable reactor modules that will accommodate those needs.

As discussed previously herein, the decontamination apparatus of this invention advantageously produces in real time an active, independent and precise pump-based flow adjustment to each W reactor module, thereby accommodating an extremely widened range of influent conditions with minimal impact upon the infrastructure of treatment facilities. Each reactor module incorporates an integral variable-speed pump such that the flow rate of any one UV reactor module does not physically force a change in the flow of any other W reactor module. Thus, unlike the prior art decontamination apparatus shown in Fig. 1, none of the UV reactor modules in the apparatus of the present invention compromises its own performance because of the flow rate changes occurring in other W reactor modules. As a result, all the UV reactor modules used in the apparatus of this invention are capable of independently achieving optimum W dosage.

While much controversy exists within the continuos wave lamp community over the means for calculating UV dose, it has appeared most convenient to view CRi dose as being the average fluence rate times the exposure time (in seconds). Most authors have used the units mw-s/cm2 (milliwatt-seconds per square centimeter). This is most simply expressed by Equation (I) below : (I) D=I. t Where: D UV dose, mW-s/cm2 = average intensity of the germicidal W energy, mW/cm2 t = exposuretime, seconds The actual W fluence rate in the typical, multiple-source continuous wave lamp reactor is a very complex calculation and, in addition to consideration of the hydraulic flow rate variability, usually involves a Multiple Point Source Summation approximation in order to accommodate the considerable variation in W output throughout the reactor volume. The light intensity field around a hypothetical point-source along the axis of a CW lamp can be described by Equation (II) belon Where : r, z radial and longitudinal coordinates (respectively) in a cylindrical coordinate system with the origin on the axis of the axis of one end of the lamp 1 (r, z) j = intensity at location (r, z) attributable to the Ith point source P = lamp output power n = number of point sources used to represent the lamp p = distance from point source to location (r, z) a = absorption coefficient for quartz envelope tq = thickness of quartz jacket envelope ai = absorption coefficient for water ri = lamp radius

For any location (r, z) the total intensity received is the sum of the contributions from all of the point sources within the system, as shown in Equation (III) below : Where : Equations (II) and (TII) represent the basic Point Source Summation model. Since this model provides spatially-dependent information about the light intensity field, this information can be used for the prediction of radiation dose accumulated by each particle in the influent stream.

Such prediction is illustrated in Equation (IV) below: r (IV) dosei) db 0 Where: dose, = UV dose received by the I'particle I (t) time-dependent LN intensity t = time T residence time of a particle within the irradiated volume The inactivation of bacteria historically has been approximated by first-order kinetics, and is considered accurate for"ideal"conditions, according to Chick's law (Chick, 1908): N = Noe(-klt) Where: N = bacterial density after exposure to W light No initial bacterial density K = inactivation rate constant (cm2/W-s) I = intensity of the UV light energy (W/cm t = exposure time (seconds) In attempts to formulate W decontamination design models, practitioners have developed more complex models that necessarily must include numerous empirically-based data parameters.

These models then become the basis for predicting system performance. It is outside the scope of this invention to tackle the existing controversy over which model is currently the best for UV decontamination performance prediction, the excellent work of Blatchley, et. al., not withstanding

(e. g., Ernest R. Blatchley III (1998J"Optimization of Process Performance in Ultraviolet Disinfection Systems,"Water Environment Federation Proceedings, Disinfection'98 The Latest Trends in Wastewater Disinfection: Chlorination vs. UV Disinfection).

However, in order to make a distinction between this invention's method and those of the prior art, the UV disinfection model (Scheible, 1987) that became the basis for the model reported in the US EPA Design Manual for Wastewater Disinfection (1986) and cited in the Wastewater Disinfection Manual (Water Pollution Control Federation, 1986) will be used herein. Such model is illustrated in Equation (V) below :

Where : u velocity of wastewater through the reactor (cm/s) x = average distance traveled by water under exposure to W light (cm) E = dispersion coefficient (cm2/s) K = inactivation rate constant (s~l) The inactivation rate, K, is an estimation based upon an empirical relationship shown in Equation (VI) below : (VI) K )' Where : Iavg = average W light intensity within the reactor a, b = empirical coefficients specific for wastewater conditions Note that this method, along with most other disinfection calculations required for continuos wave lamp processes, must necessarily be concemed with typically reactor-specific and varying time-base terms, such as: exposure time, particle residence time, reactor water velocity, and time-dependent W intensity.

In the present invention, the use of a single pulsed lamp in each reactor simplifies both the accurate delivery and determination of UV dose. This is because the discrete, pulsed-energy delivery method of UV flashlamp technology can remove the time-dependent element from the calculations.

When one knows the reactor's flow rate (in m3/sec), and indeed, this invention provides for this information at any instant, then the terms"average fluence rate"and"exposure time"can both be

replaced by"UX Joules per pu) se" (J J times the"putse repetition rate" (Hz). Therefore. w e can simply and more conveniently measure lez'-C dose in terms of average UT-C joules per cubic meter a/m3), and base our disinfection model (s) upon this accurately quantified variable.

Additionally, the coaxial arrangement within the reactor of a single, linear light source (a pulsed, high-intensity UV flashlamp) further simplifies the delivery of LW light and provides a less- cumbersome approach towards an accurate calculation of performance. It is also advantageous to calculate a UV reactor's actual performance in real-time, instead of basing a real-life operation of the process method (and primarily relying) upon predictions of reactor performance. The method of this invention embodies this important distinction.

It is well known that various W disinfection operations can more efficiently achieve a desired outcome by determining the optimum W delivery conditions for the specific process. This process is a matter of balancing the three primary contributing factors: fluid flow rate, fluid condition (contaminant levels and W transmission characteristics), and the amount of UV power applied to (and subsequently absorbed) by the targeted organism or compound. Since these three factors dominate the process and largely determine the process efficacy, it is these three factors that are addressed by the method taught herein.

Although U. S. Patent No. 5,144,146 ("the'146 patent") sets forth teachings regarding the framework around which toxic substances may be destroyed by the light from pulsed UV flashlamps (in terms of bandwidth, average and peak power intensities, and so on), such teachings are in reality a simple summation of the boundary conditions wherein nearly all successful W dissociation processes have been openly performed by so many others over the past few decades. The fact that the broad conditions outlined in the'146 patent do encompass a large multitude of real and potential process operations (that are entirely unspecified and, likewise, without corresponding specific UV requirements) does not in any manner express anything in particular, other than what has for decades been a very general and common knowledge among those familiar with the art. That is: the variable power output of pulsed flashiamps can be tailored to fit the desired W conditions determined best for a particular photodissociation process. If one defines the range of the various energy delivery modes (such as average and peak power, and so on) that are useful for nearly all W flashlamp-based photodissociation process, then that range would in essence be those conditions set forth in the'146 patent.

Therefore, this present invention utilizes the output spectra of pulsed flashlamps in various combinations of average and peak intensity within (and even outside, i. e., < 5 Hz pulse repetition rate) the operanonal bounds specified by the'146 patent, as have essenially all other users of CR~ flashiamp technology over the decades. The open ilterature clearly makes this evident. Indeed, this flexibility in output configuration afforded by pulsed high intensity lamps has ahvays made them an ideal candidate where greatly varying amounts and intensities of W light is beneficial.

In prior art attempts to simultaneously accommodate both varying influent and lamp output conditions, previous processes such as that taught, e. g., in U. S. Patent No. 4,336,223 to Hillman, have utilized turbidity detectors in a feedback loop. Turbidity is defined as the reduction of transparency in water due to the presence of suspended particles. Although the measurement of turbidity and its contribution towards an optimized W dosage is considered a claim of this prior art, turbidity is actually just one factor affecting the ability of W light to penetrate the reactor volume, or UV transmission. For instance, minute amounts of certain commonly encountered industrial waste can drastically lower the percentage of UV transmission, even though turbidity measurements upon that same fluid might indicate a low turbidity level. When UV dose is determined via such low turbidity readings, the consequentially incorrect assumptions result in inadequate UV dose and non- compliant discharges from the process.

The Beer-Lambert Law describes how light is attenuated when any material within a fluid absorbs that light. The attenuation factor or transmittance T# for a given light beam of wavelength where the attenuation is due primarily to absorption is described in Equation (VII) below : (V(VII)r;=t0" Where : oc = absorption coefficient (cm~l) at A I = path length (cm) Photochemical processes can be initiated only by the photons that are absorbed by the targeted medium. Absorbance is related to the concentrations of absorbing constituents in accordance with Equation (VIII) below : where : sa, C = molar absorption coefficient (Mr cmv) at wavelength X and concentration (NI) of constituent i in the fluid

/= pathlength (cm) Absorbance and transmittance are related by Equation (IX) below : (IX) <BR> <BR> (IX)<BR> <BR> <BR> or or While suspended solids can absorb light and contribute to a reduction in UV transmittance, it is commonly known that this does not always have a linear effect, and neither does it necessarily dominate the process. In terms of importance to any photodissociation process requiring accurate dosage of UV light, the measurement of UV transmission is more meaningful than turbidity.

Therefore, processes that rely upon monitoring fluid turbidity when determining actual UV dosage can be entirely inaccurate and ineffective. The method of the present invention advantageously measures W transmission instead of turbidity, and incorporates in each UV reactor module a detector interface for use with one or more W transmission detectors. Such detector interface also allows the addition of auxiliary contaminant level detectors. Such detection tools will become widely available in the future, providing real-time indication of various contaminants of interest, such as microorganisms and toxic organic compounds. The method and apparatus of the present invention enable additional and important closed-loop feedback capabilities that can further increase the accuracy an efficiency of large-scale UV photodissociation applications.

\Vhile the foregoing description includes detail which will enable those skilled in the art to practice the invention, it should be recognized that the description is illustrative in nature and that many modifications and variations will be apparent to those skilled in the art having the benefit of these teachings.