Patent Publication Number: US-2006018785-A1

Title: Apparatus and methods for variably sterilizing aqueous liquids

Description:
This U.S. Patent Application is a Continuation of U.S. patent application Ser. No. 10/626,373, titled APPARATUS AND MEHTODS FOR VARIABLY STERILIZING AQUEOUS LIQUIDS, and filed Jul. 24, 2003. 
    
    
     FIELD OF INVENTION  
      This invention relates to apparatus and methods by which aqueous (water based) liquids are decontaminated for culinary and other uses, such as for medical purposes. This invention is further related to methods which may decontaminate such aqueous liquids without use of chemical or light energy processes.  
     BACKGROUND OF THE INVENTION  
      There is an ever increasing need for new, more effective, efficient and lower cost methods for decontaminating water and other water based (aqueous) liquids. A profound example of changes in methods of water purification is a new water treatment plant located in Salt Lake City, Utah. Rather than chlorine, this plant employs ozone and ultraviolet light, as ultraviolet light is more effective than chlorine in terms of decontaminating water containing cryptosporidium and other chlorine resistant microbes. However, use of light is known to sometimes be ineffective and at other times be unpredictable when used in water that has variable light transmission quality.  
      While decontamination and purification are terms generally considered in an ultimate context of complete elimination of any and all undesirable contaminants, it is generally known, as disclosed on page 68 of  Principles and Methods of Sterilization,  2 nd  Edition, published by Charles C. Thomas, Springfield, Ill., in 1983, that complete sterilization should never be considered as completely attained. Rather, biological contaminants should be considered to be eliminated logarithmically, such as being measured by time constants dependent upon intensity and method of treatment. As an example, if a process kills a particular organism at a rate of 90% per minute, 10% of the organism survives at the end of the first minute of treatment. One percent survives the second minute of treatment and to achieve a kill of 99.9999% requires a treatment period of six minutes.  
      To codify a standard for sterilization, the Association for the Advancement of Medical Instrumentation (AAMI), 110 N. Glebe Road, Suite 220, Arlington, Va. 22201-4795 has issued a proposed standard for selecting appropriate Sterility Assurance Levels (SALs)(See  Proposed Standard on Selecting Appropriate Sterility Assurance Levels  published as an Internet bulletin on Feb. 10, 2000). While, SALs are generally used to determine levels of sterilization for medical products, a similar standard may be considered for water and other aqueous liquid purification, as well. AAMI reports, as examples, that items which come into contact with skin may need only an SAL of 10 −3  while implants or sterile liquid pathway products should be sterilized to an SAL of 10 −6 .  
      Similar considerations might be applied to water purification. Drinking water from one source might be sufficiently pure at an SAL of 10 −3  while another source might require an SAL of 10 −4  or better. It may also be desired to have a single water purification or sterilization system which could be used for various purposes (e.g. for drinking water or for a medical application). Also, such aqueous liquids as milk might require different sterilization for different packaging and storage requirements. This invention is meant to fulfill a variety of applications related to meeting requirements for a variety of sterilization levels.  
     BRIEF SUMMARY AND OBJECTS OF THE INVENTION  
      In brief summary, this novel invention alleviates all of the known problems related to safely and efficaciously decontaminating aqueous liquids for a variety of uses. In one embodiment, the invention is a “flow-through” device which receives influent contaminated liquid or impure liquid of questionable pollution and provides a sterilized effluent product which may be variably decontaminated to meet a variety of applications. Further, sterilization levels (i.e. SALs) may be facilely, accurately, predictively and variably controlled, depending upon known or assumed characteristics of an influent liquid to be sterilized and projected use of that liquid.  
      The invention comprises a liquid source, a flow and pressure controller which provides a variable control setting for both flow and pressure of influent liquid. From the source, liquid is distributed via closed reservoir (e.g. coils) within a heating chamber. The reservoir has a capacity which holds a liquid volume at least equal to a given maximum desired flow rate for a time necessary for sterilizing the liquid to a predetermined SAL value.  
      Strategically disposed in thermal communication with the reservoir is a temperature sensor which is used to assure that liquid flowing through the heating chamber is at least at a temperature which is consistent with a desired sterilization temperature. Of course, the controlled flow rate determines dwell time in the heating chamber and, therefore, an ultimate SAL value of effluent liquid streaming from the heating chamber.  
      Heating should be accurately controlled and may be performed by such heat sources as electric elements, gas burners, solar and/or geothermal energy. To assure that heating is sufficiently accurately controlled, it is preferred that the heating chamber provide an accurately controlled temperature “bath” through which the liquid flows. Presently, an oven filled with a paraffin having a predetermined melting temperature is employed to maintain a precise oven temperature.  
      Actual sterilization efficiency is dependent upon maintaining a liquid temperature above 100° Centigrade (e.g. 150° Centigrade) at a pressure (e.g. 50 psi) which assures achieving a desired SAL as liquid flows through the reservoir. Depending upon a preprogrammed dwell time in the reservoir, sterilization temperature may be variably determined to achieve a desired SAL. Alternately, and preferably, flow rate may be varied to achieve a target SAL.  
      Other than flow control at the source or influent site of the reservoir, two other flow control elements are employed. Downstream, near the effluent site of the reservoir, a pressure relief valve is disposed in the effluent flow path to guarantee that a predetermined minimum upstream pressure is maintained within the reservoir. Another, second, valve is also serially disposed in the flow path, preferably distal from the oven and the pressure release valve.  
      The second valve is selectively gated by an “AND” combination of water temperature and pressure sensors. The temperature and pressure sensors are each disposed at individual predetermined strategic sites within the water flow path. In one embodiment, temperature is sensed by a bi-metallic sensor switch disposed within the reservoir, sufficiently close to the influent site of the reservoir to assure that a predetermined minimum sterilization temperature has been achieved, thereby assuring maintenance of the minimum sterilization temperature within the remainder of the reservoir. In this embodiment, a pressure sensor, having a pressure-sensitive switch, is disposed downstream from the reservoir. The pressure sensor is selectively closed when a predetermined sterilization upstream pressure is detected. The contacts of the temperature sensor and pressure sensor are connected in series such that when contacts of each switch close the second valve is opened (i.e. before the second valve opens, the temperature sensor must sense at least a predetermined temperature and the pressure sensor, likewise, must have detected a predetermined pressure.)  
      Also, each switch of each sensor are opened and closed at different values (of temperature and pressure), thereby creating a hysteresis in each switching parameter and, as a result, assuring stable operation. For example, the temperature sensor may operate to close the temperature switch at a temperature of substantially 150° and operate to open the switch at 140°. In tandem with the temperature sensor, the pressure sensor may operate to close the pressure switch at 80 psi and open the pressure switch at 50 psi. Only when both switches are closed is the second valve opened.  
      To preserve as much energy as possible, it is preferred to steer oven effluent through a heat exchanger which transfers heat from the effluent to the oven influent such that temperature, and therefore thermal energy, of liquid flowing from the second valve is substantially reduced. In this manner, by controlling dwell time in the reservoir (in the oven) by controlling liquid flow within predetermined limits, liquid of a desired SAL is provided as a cooled continuous flow effluent product.  
      Accordingly, it is a primary object to provide an efficacious aqueous liquid purification system which controllably sterilizes aqueous liquid to a predetermined SAL.  
      It is a fundamental object to provide an aqueous liquid purification system which controllably sterilizes an aqueous liquid to a predetermined level by controlling one or more of: 
          (a) rate of flow of the aqueous liquid through said system,     (b) temperature at which the aqueous liquid is sterilized and/or     (c) pressure at which the liquid is maintained throughout sterilization.        

      It is an important object to provide a system which inherently maintains a predetermined pressure in a heating unit thereby assuring that aqueous liquid in the heating unit is maintained in a substantially liquid state while being sterilized therein.  
      It is an object to provide a process by which a heating unit, through which aqueous liquid flows and in which the aqueous liquid is heated, is maintained at a precise temperature.  
      It is an object to provide a system which assures a predetermined pressure of effluent flowing from said system.  
      It is an object to provide an energy efficient system which transfers energy from effluent liquid, after sterilization, to influent liquid before sterilization, thereby reducing effluent temperature to a predetermined safer lower temperature level before leaving the system and preheats influent aqueous liquid before it enters the heating unit.  
      These and other objects and features of the present invention will be apparent from the detailed description taken with reference to accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is schematic of an aqueous liquid sterilization system which may be adjusted to control degree of purification (SAL).  
       FIG. 2  is a schematic of a test system model used to determine effectiveness of a sterilization process consistent with the instant invention. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
      In this description, the term proximal is used to indicate nearness of a referenced item to the object of the sentence describing its position. The term distal should be interpreted as indicating “away from” a referenced item. Numbers and primes of the same numbers are used to indicate items of related mechanics and function, but which may have physical differences.  
      Reference is now made to the embodiment illustrated in  FIG. 1 . While only a single embodiment is provided herein, it should be apparent to one skilled in water and other aqueous liquid purification by sterilization that other embodiments may be employed within the scope of the invention.  
      As seen in  FIG. 1 , a water sterilization system  10  comprises an influent channel  20 , wherethrough water from a source  22  (see arrow  24 ) is delivered, a pump subsystem  30 , a heat exchanger  40  through which influent liquid flows in an input pathway  50  and through which effluent liquid flows in an output pathway  60 , a pressurized heating chamber  70  and a discharge pathway  80  (see arrow  82 ).  
      Pump subsystem  30  comprises a pump  100  and a pump controller  102 . Pump  100  should have a variable pumping capacity to supply a predetermined volume of liquid flow through the system against a back pressure which is the consequence rising of a temperature rise in heating chamber  70  and back-pressure of release valve  130 . It should be noted that no pump may be required if pressure of the source exceeds the back pressure. However, in both cases, it is necessary to control flow to assure liquid is retained in heating chamber  70  for a period sufficiently long to achieve a desired SAL. In cases where flow is not pump controlled and upstream pressure is known, a flow restricting orifice may be employed. In those instances where controlled flow rates are used to variably determine SALs of effluent, an adjustable orifice may be employed.  
      Heat exchanger technology is well known in water heating and cooling art. However, it is important that as much energy as possible be transferred from liquid in output or effluent pathway  60  to input or influent pathway  50  within heat exchanger  40  to minimize heat energy loss. For these reasons, pathway  50  should be proximal to and in good thermal communication with pathway  60 .  
      It is critical that the system liquid pathway  118  (a combination of input pathway  50 , an internal heating chamber pathway  120  and output pathway  60 ) be capable of withstanding an internal pressure generated by heating of liquid within the pathway to a desired temperature while maintaining the liquid state. As an example, liquid at 150° Centigrade has a vapor pressure of 55 pounds per square inch (psi). To assure liquid at 150° does not change state, internal pressure in pathway  118  must exceed 55 psi.  
      For this reason, a flow resisting element, such as a pop valve  130  is serially connected in a section of output pathway  60  distal from heating chamber  70  and heat exchanger  40 . To further assure that there is no flow through pathway  118  (and discharge pathway  80 ) until conditions for water sterilization have been reached in heating chamber  70 , a second valve, numbered  140 , is serially connected in discharge pathway  80 . In this embodiment, valve  140  is a solenoid valve activated by an AND combination of two switches, a pressure sensor switch  150  and a temperature sensor switch  160 .  
      Each sensor switch ( 150  and  160 ) activates to open at a first predetermined level and closes at a second predetermined level. For example, pressure sensor switch  150  may be selected to close at 80 psi and open at 55 psi, while temperature sensor switch  160  may close at 150° centigrade and open at 140° centigrade. As such, switch  150  must sense  80  psi and switch  160  must sense 150° centigrade (symbolized by AND gate  162 ) to open valve  80  to permit effluent to flow through system  10 . Note, pressure sensor switch  150  is connected to AND gate  162  via line  164  and temperature sensor switch  160  is connected to AND gate  162  via line  166 .  
      To sterilize water at least to a predictable SAL, both system  10  water flow rate and heating chamber  70  temperature must be known and well controlled to assure liquid in pathway  120  is resident in heating chamber  70  for a long enough period to assure the desired sterilization level. Water flow rate may be closely controlled by pump  100  and pump controller  102 . Temperature is preferably induced in liquid in pathway  120  by a high heat capacity bath  170  which has high heat transfer and precise temperature control characteristics.  
      While other media may be used in such a bath, such as oil or high heat capacity fluids, it is preferred to use a precisely specified paraffin, such as matter  180 . In this case, matter  180  is a stable substance which changes state from a solid to a liquid and maintains a constant desired predetermined temperature during the state change. Particularly suited for use in bath  170  is paraffin. Paraffin may be formulated to accurately and precisely melt at a selected temperature between 100° centigrade and 170° centigrade. Such paraffin is currently available from ASTOR Specialty Chemicals, 160° Commerce, Marshall, Tex. 75670. As an example, matter  180  may be selected to have a melting point of 150° centigrade.  
      Heating of matter  180  is accomplished by a set of electrical heating elements, generally referenced by  182 , which are turned off and on by a bimetallic temperature switch  184 . Heating elements  182  are powered by a standard electrical plug assembly  186  which is interconnected to heating elements  182  via electrical lines  183 ,  185  and  188 . Bimetallic temperature switch  184  is interposed between line  183  and line  185 . Dashed lines indicate electrical line residence in bath  170 .  
      Switch  184  is selected to open at a temperature which is fractionally above the melting point of matter  180  (e.g. 152° centigrade and to close at a temperature at or just below the melting point of matter  180  (i.e. 150° centigrade). So constrained, heating of matter  180  is the result of a hysteresis effect, making operation stable.  
      System  10  may be constructed from a large number of parts generally available in commerce today. Examples of parts which may be used are as follows:  
      System  10  Part Commercial Part 
          Pump  100  Flojet Pump model #03655E7011A, available from Flojet, ITT Industries, 201 CON, Fort Hill Ranch, Calif.     Temp. Sensor Switch  184  Texas Instruments 20260 bimetal thermal switch, Normally Closed.     Temp. Sensor Switch  160  Texas Instruments 20260 bimeatl thermal switch, Normally Open.     Pres. Sensor Switch  150  Texas Instruments 36PS-50 psi, Normally Open.     Heating Elements  182  TEMCO Finned Strip Heaters, Type 4, 500 Watt, available from TEMCO, 607 North Central, Wood Dale, Ill. 60191.        

      Valve  140  Solenoid Valve #4639K8 (120 volt, 0.13 Amps), available from McMaster-Carr Supply Co., www.mcmaster.com. 
          Press. Rel. Valve  130  CA Series In-line Adjustable Relief Valve having a cracking pressure range from 50 to 150 PSIG, available from NUPRO Company, 4800 East 345 th  Street, Willoughby, Ohio 44094.        

      Pathway  118  Preferably constructed from high pressure, stainless steel tubing (with all joints welded to withstand temperatures above melting temperature of matter  180 ).  
      The time to sterilize an item, using saturated steam at a given temperature is well known and summarized in Table 1 below:  
                           TABLE 1                                       Sterilization           Time to sterilize   temperature                          20 minutes   121° Centigrade           10 minutes   128° Centigrade            3.5 minutes   134° Centigrade           Nearly instantaneous   141° Centigrade                      
 
 However, data in Table 1 is not directly related to SALs. Therefore, some nominal experimentation may be necessary to develop known sterilization criteria for each system  10 . Through experimentation it has been found that water sterilization by system  10  at different parametric levels of flow and temperature yields different SALs for assorted species tested. It should not be surprising that SALs vary for different microbes and other water-borne organisms. 
 
       FIG. 2  is a schematic representation of a test model  200  used to test effectiveness of sterilizing aqueous solutions by processes consistent with the instant invention. As seen in  FIG. 2 , model  200  comprises a source  22 ′ of influent contaminated water. In this case, source  22 ′ is a  60  gallon drum strategically disposed above a pump  100 ′ for easy priming.  
      Similar to system  10  seen in  FIG. 1 , model  200  comprises an influent channel  20 , wherethrough water from a source  22 ′ (see arrow  24 ) is delivered, a pump  100 ′, a heat exchanger  40 ′ through which influent liquid flows in an input pathway  50 ′ and through which effluent liquid flows in an output pathway  60 ′, a pressurized heating chamber  70 ′ and a discharge pathway  80 ′ (see arrow  82 ).  
      Pump  100 ′ is manually controllable. Pump  100 ′ has a variable pumping capacity which is manually adjusted to supply a predetermined volume of liquid flow through the system. A needle valve  140 ′ is used for manual control of flow through model  200 . Temperature of solution in pathway  120 ′ (which is the in heating bath portion of total system pathway  118 ′)is monitored by means of a temperature sensor  210  (a thermocouple) and a graphic recorder  220 . Note that an electrical line  222  interconnects sensor  210  and recorder  220 . In this model, an Esterline Angus Video Graphic Model B recorder was used.  
      Energy supplied to heating elements  182  of oven  70 ′ of model  200  was monitored by a voltmeter  230  and an ammeter  240 . Varying amounts of energy was supplied from electrical plug assembly  186  to heating elements  182  and therefrom to bath  170  of oven  70 ′ via a variable voltage rheostat  250 . Note that electrical lines  183 ′,  185 ,  187 ′ and  188 ′ are used to supply electrical energy to heating elements  182 . Line  183 ′ interconnects assembly  186  and one side of temperature sensor switch  184 . The other side of temperature sensor switch  184  is connected to heaters  182  via electrical line  185 . Ammeter  240  is placed in series (via electrical line  187 ′) from plug assembly  186  to rheostat  250 . Rheostat  250  is connected to heating elements  182  via electrical line  188 ′.  
      Model  200  system liquid pathway  118 ′ was designed to be capable of withstanding any internal pressure generated by heating of liquid within the pathway to temperatures within the scope of reasonable experimental safety limits while constraining liquids in pathway  118 ′ to remain in a liquid state.  
      In model  200 , liquid pathway  118 ′ had a volume of 600 ml. Temperature was held between  143  and  144  degrees centigrade. Pump  100 ′ supplied liquid at a constant pressure of 95 psi. Heat exchanger  40 ′ employed coaxial piping. Pop valve  130  (a pressure release valve) was rated at 50 psi. As earlier disclosed, needle valve  140 ′ was used to manually regulate flow rate through pathway  118 ′.  
      Temperature of pathway  118 ′ was manually monitored by thermocouple  210  placed in thermal communication with pathway  118 ′. As earlier disclosed, an Estiline Angus model videographic system B (recorder  220 ) was used to continuously monitor temperature. Variations in temperature caused by increasing or decreasing rate of flow were adjusted by rheostat  250  which adjusted electric power supplied to a set of heating elements, generally referenced as  182 . In model  200 , four such 500 watt heating elements were employed.  
      Biologic testing was performed to determine effectiveness of sterilization at different flow rates using water contaminated with the following four different microorganisms: 
          1.  Bacillia sterothermopbilus       2.  E. coli       3.  Candida Aldicans       4.  Pseudomonas aeruginosa          

      A predetermined quantity of each microorganism was mixed with 25 gallons of distilled water and dispensed into a drum to provide source  22 ′. A serial dilution of each batch of microorganisms was titrated and tested to establish the concentration of each organism in the batch. Every batch prepared was determined to contain at least 10 6  organisms.  
      Each of the four test organisms were run in duplicate on different days. A test protocol was prepared to run five different effective sterilization periods on each organism. Generally, flow rates employed were divided into a plurality of constant flow one and one-half hour periods. In the runs, flow rates used ranged from 50 to 350 milliliters per minute, in 50 milliliter per minute increments. However, due to lack of meaningful results at lower flow rates and limits on volumes of solution available in model  200 , less than a complete complement of flow rates were often used, e.g. 250, 300 and 350 milliliters/minute were used in a test run performed on Apr. 25, 2003, results of which are provided hereafter.  
      Samples were taken at fifteen minute intervals throughout each test period (providing seven samples per period). Each sample was tested by placing a milliliter aliquot onto a blood agar or enriched agar plate, incubated for 48 hours and read by a qualified microbiologist. As seen by the examples of data provided hereafter, kill ratio of each sample generally exceeded a 10 −6  organism reduction in processed effluent.  
      Though all tests showed similar sterilization results, a summary of two tests using bacillia sterothermopbilus are provided, in Tables 3 and 5 below, as exemplary results of running model  200 . Dates of performance of the exemplary tests were Apr. 19, 2003 and Apr. 25, 2003. For each test run, content of source  22 ′ was titrated as a control. Two sets of such results, one set for each solution tested on Apr. 19, 2003 and Apr. 25, 2003, are provided separately in Tables 2 and 4, respectively.  
               TABLE 2                          Titration of Stock Culture Used 4/19/03       Sample volume is 1.0 ml/each dilution       (unless otherwise noted).       Plates incubated @ 59° C. for 18 hours                                 Event   Dilution   Colonies                                             1   10 −1     TNTC **           2   10 −2     TNTC **           3   10 −3     TNTC **           4   10 −4     TNTC **           5   10 −5     no record           6   10 −6     no record           7   10 −7     600           8   10 −8     ***           9   10 −9     ***           10    10 −10     ***           11   10 −0  * (Stock)   TNTC **                         * 0.250 ml sample volume                ** Too Numerous To Count                *** Titration not performed due to measurable level at event 7             
 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                   
               
               
                 Test Run 4/19/03 (Temperature of pathway 118′: 143 to 144 ° C. 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Flow Rate 
                 Time in minutes 
                   
               
               
                   
                 Run # 
                 (ml/min) 
                 (within run) 
                 Colonies 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 I 
                 100 
                 0 
                 2 ** 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 
                 0 
               
               
                   
                   
                   
                 90 
                 0 
               
               
                   
                 II 
                 150 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 
                 0 
               
               
                   
                   
                   
                 90 
                 0 
               
               
                   
                 III 
                 200 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 
                 0 
               
               
                   
                   
                   
                 90 
                 0 
               
               
                   
                 IV 
                 300 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 * 
                 450  
               
               
                   
                   
                   
                 45 * 
                 150  
               
               
                   
                   
               
               
                   
                   * See note (reference [*]) following Table 5.    
               
               
                   
                   ** Initial contamination in effluent pathway.    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                   
               
               
                 Titration of Stock Culture Used 4/25/03 
               
               
                 Sample volume is 1.0 ml/each dilution 
               
               
                 (unless otherwise noted). 
               
               
                 Plates incubated @ 59° C. for 18 hours 
               
            
           
           
               
               
               
               
            
               
                   
                 Event 
                 Dilution 
                 Colonies 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 1 
                 10 −1   
                 TNTC ** 
               
               
                   
                 2 
                 10 −2   
                 TNTC ** 
               
               
                   
                 3 
                 10 −3   
                 1000 
               
               
                   
                 4 
                 10 −4   
                 400 
               
               
                   
                 5 
                 10 −5   
                 250 
               
               
                   
                 6 
                 10 −6   
                 180 
               
               
                   
                 7 
                 10 −7   
                 120 
               
               
                   
                 8 
                 10 −8   
                 75 
               
               
                   
                 9 
                 10 −9   
                 64 
               
               
                   
                 10 
                 10 −10   
                 25 
               
               
                   
                 11 
                 10 −0 * (Stock)   
                 TNTC ** 
               
               
                   
                   
               
               
                   
                   * 0.250 ml sample volume    
               
               
                   
                   ** Too Numerous To Count    
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                   
               
               
                 Test Run 4/25/03 (Temp. of pathway 118′: 143 to 144 ° C. 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Flow Rate 
                 Time in minutes 
                   
               
               
                   
                 Run # 
                 (ml/min) 
                 (within run) 
                 Colonies 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 I 
                 250 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 
                 0 
               
               
                   
                   
                   
                 90 
                 0 
               
               
                   
                 II 
                 300 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 
                 0 
               
               
                   
                   
                   
                 90 
                 0 
               
               
                   
                 III 
                 350 
                 0 
                 0 
               
               
                   
                   
                   
                 15 
                 0 
               
               
                   
                   
                   
                 30 
                 0 
               
               
                   
                   
                   
                 45 
                 0 
               
               
                   
                   
                   
                 60 
                 0 
               
               
                   
                   
                   
                 75 * 
                 1000 
               
               
                   
                   
               
               
                   
                   * Tank take-off connection at a point 2.5 gallons from tank bottom. Test samples were taken until flow became erratic due to tank drainage. This variation in liquid flow caused oven temperature to first increase rapidly, turning off bimetal over temperature protectors (not otherwise disclosed) resulting in a dramatic decrease in operating temperature. Data at run #III, time 75 minutes (and at run#II, times 30 and 45 minutes) provided to permit a comparative assessment with data    
               
               
                   
                 # derived from system 200 under normal operating conditions.  
               
            
           
         
       
     
      Results from all tests proved the efficacy of the instant invention. Independent of microorganisms tested and flow rates tested, system model  200  clearly sterilized contaminated influent to produce a continuously flowing sterilized effluent. The effectiveness of sterilization was demonstrated when compared with final samples of contaminated and unsterilized effluent which resulted when temperature of model  200  precipitously declined as an end-of-run phenomenon when water from source  22 ′ was depleted.  
      The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.