Abstract:
Provided is a “parts washer” that includes a fluid that performs a cleaning function and maintains the viability of microorganisms in the fluid which biodegrade organic material in contact with a biological component, the parts. “Parts” include objects befouled with organic material and/or particulate matter. The cleaning fluid includes a surfactant that functions to separate organic waste from the parts being washed. A multi-tiered basin houses the cleaning fluid and the biological component living within the fluid that breaks down organic wastes produced by the cleaning fluid. The multi-tiered basin which forms the mechanical component of the washer, includes a sink member with a false bottom, and a support grid and filter to support microorganisms interposed between the false bottom and a bottom panel of the sink member. The tank is partially filled with the cleaning fluid and a pump and conduit assembly directs a flow of the cleaning fluid to the basin and aerates the cleaning fluid. Recirculation is facilitated by discharge of the cleaning fluid into the basin to flow through a drain hole in the false bottom, through the filter and support grid, and then through a drain hole in the bottom panel of the sink member back into the tank for reuse. A heater, thermostat, and a level control assembly function to maintain the cleaning fluid within a certain temperature range so as to maintain a proper environment for the microorganisms.

Description:
This application is a divisional, of application Ser. No. 08/370,898, filed Jan. 10, 1995, now abandoned, which is a continuation of Ser. No. 08/315,902 filed Sep. 30, 1994, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present application claims priority from U.S. Ser. No. 08/315,902, filed Sep. 30, 1994, now abandoned. 
     A parts washer including a mechanical, fluid and a biological component, reduces environmental problems of waste disposal. “Parts” include objects fouled with organic and particulate matter such as automotive parts. 
     Parts washers are employed in the cleaning of parts that are contaminated with organic waste products such as hydrocarbons, oils, greases, road dust and grit. The type of parts washed in a parts washer include automotive parts such as nuts, bolts, valves, pistons, carburetors, transmission parts, and the like. Most conventional parts washers include a basin mounted on the top of a tank. The tank is partially filled with a mineral spirits solvent that is pumped from the tank through a conduit that discharges into the basin where the parts are washed. The mineral spirits solvent drains from the basin back to the tank for reuse. A filter is sometimes interposed in the solvent flowpath to collect organic waste products and particulates washed from the parts. 
     Although mineral spirits are an effective cleaning solvent, there are many drawbacks to the employment of parts washers that utilize mineral spirits. For example, mineral spirits solvents are presently classified by government regulatory agencies as hazardous materials because of their low flash point and potential health concerns. For example, contact dermatitis is common for operators of parts washers who generally do not wear gloves. Because of this classification, mineral spirits must be used, handled, and disposed of in compliance with extensive government regulations. Further, mineral spirits that are not properly contained can have a negative impact on the immediate work environment, and it is not uncommon for workers to have dermatitis and respiratory problems exacerbated by the unprotected use of mineral spirits. Additionally, many users of mineral spirits find it necessary to dispose of used mineral spirits by having a licensed waste disposal company pick up the used mineral spirits so that the used mineral spirits can be disposed of in compliance with the various governmental guidelines and regulations; such disposal can be expensive. 
     Filters are generally incorporated into conventional parts washers to separate the organic waste products and particulates from the solvent. A problem is that the filters eventually become saturated with organic waste products and particulates and therefore need to be replaced. The filters are often difficult to access and replace. Furthermore, the filters, after they have absorbed the organic waste products, are often considered hazardous material and are therefore difficult to dispose of according to legal restrictions. 
     There is, therefore, a need in the industry for a system which provides for parts washing and reduces environmental problems associated with mineral spirits as a cleaning (washing) component. 
     SUMMARY OF THE INVENTION 
     A system for parts washing employs a combination of a cleaning fluid and a biological agent as a method to replace the mineral spirits of other parts washers. “Parts” as used herein include objects befouled with organic and/or particulate matter. Parts cleaned according to the invention include automotive parts, equipment parts and machinery parts. Objects are inanimate, non-biological objects such as metal or plastic. The cleaning fluid serves two purpose: 1) cleans parts; and 2) maintains the viability of the biological agent. An apparatus is developed that is suitable for implementation of the method. 
     The cleaning fluid includes a surfactant that functions to remove organic waste from the parts being washed. The biological component includes microorganisms that digest the organic waste. The cleaning fluid is not toxic to the microorganisms, therefore the microorganisms survive and reproduce within the cleaning fluid environment. The present invention comprises a parts washing system characterized by a cooperative interaction among a mechanical component, a fluid component, and a biological component. The parts washer apparatus (herein also referred to as the “parts washer”) of the parts washing system includes, a holding tank, cleaning fluid retained within the tank, microorganisms living with the cleaning fluid, a wash basin, a fluid delivery system, an in-line filter to which microorganisms are affixed, and an electrical control system for maintaining an environment conducive to maintaining and promulgating the life of the microorganisms. 
     In an illustrative embodiment, the wash basin of the parts washer is a multi-tiered basin including a sink member defining a bottom panel and a false bottom disposed above the bottom panel. The multi-tiered basin further includes a support grid and filter interposed between the false bottom and the sink member. The false bottom, support grid, and filter are readily removable from the sink member. The holding tank is partially filled with the cleaning fluid, and a pump and conduit assembly direct a flow of the cleaning fluid to the basin. The cleaning fluid discharged into the basin flows through a drain hole in the false bottom, through the filter and support grid, and then through a drain hole defined through the bottom panel of the sink member, finally the cleaning fluid is then returned to the tank for reuse. The pump and conduit assembly functions to aerate the cleaning fluid; and a heater, thermostat, and level control assembly function to maintain the cleaning fluid within a certain temperature range so as to maintain a proper environment for the sustainment of the microorganisms. The microorganisms are preferably introduced into the cleaning fluid in a dormant state. The microorganisms in the dormant state are preferably adhered to the filter prior to use, for example by an adhesive, and released from the filter when the cleaning fluid flows through the filter by dissolution of the adhesive and the force of the flow. For example, a microorganism “sandwich” is made by spraying an adhesive layer on the filter, dusting powdered microorganisms over the adhesive then spraying the microorganism layer with an adhesive layer. 
     The present invention optionally includes retrofit components to parts washers currently using mineral spirits. A conversion kit consisting of the cleaning fluid, a thermostatic heating element, a filter pack with dormant microorganisms, and special adapter fittings is used to convert a parts washer using a method of cleaning other than that of the present invention, to the biodegrading system of this invention. Adaptations of the kit can be specifically tailored for; tumblers, vibrator cleaners, and other agitation systems including those using fluid jet and sprays that also presently use mineral spirits. 
     An ultrasonic tank and brushes may work in conjunction with the cleaning fluid to expedite the breaking up of encrusted organic waste and particulates. For example, an electrically driven ultrasonic transducer located in the base of a brush may act alone or in combination with one or more larger (or macro) motions which, include vibration of brush bristles axially or rotationally, and continuous rotation of the brush bristles about one or more axis. Power is derived from either electrical or fluid turbine components. 
     In summary the present invention provides a new system for washing parts. A biological component is sustained within the parts washer by means of the fluid component, which also has a cleaning function. The parts washing system is “environmentally friendly,” for example, it decreases the production of hazardous waste materials. Organic waste is broken down into its non-contaminating components by the combined action of the fluid component and the biological component. The parts washer system does not require frequent fluid replacement due to recirculation. The only fluid loss is that due to evaporation. Structurally, the apparatus of the present invention is a parts washer with a multi-tiered sink structure, and a readily accessible and replaceable filter. Parts are washed and resultant organic waste is continuously recirculated in a closed, self contained environment. Consequently, the need for disposal of organic waste washed from parts is greatly reduced; in fact, generally eliminated. 
     An advantage of the parts washing system is that it does not employ a volatile and flammable cleaning fluid, in contrast to most conventional parts washers. Consequently, an automatically closing lid is not required on the parts washer of the present invention to isolate the cleaning fluid in case of a shop fire. 
     Users of the invention attest that it is “kind to hands”. In fact, instead of needing to wash their hands many times as necessitated by mineral spirits contact, the parts washer of the present invention, actually cleans the users&#39; hands. 
     Other features and advantages of the present invention will become apparent upon reading and understanding the specifications, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exterior perspective view of a parts washer in accordance with the present invention. 
     FIG. 2 is a cut-away, perspective, exploded view of isolated components of the parts washer of FIG.  1 . 
     FIG. 3 is a front, vertical cross-sectional, cut-away view of the parts washer of FIG. 1, wherein certain portions of the parts washer are not cross-sectioned or cut-away. 
     FIG. 4 is a perspective, cut-away view of a filter pad portion of the parts washer in accordance with the present invention. 
     FIG. 5 illustrates the average ppm and standard deviation for oil and grease removed with and without microorganisms. 
     FIG. 6 illustrates the steady state in ppm over time during routine parts washing using solvent and microorganisms. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in greater detail to the drawings in which like numerals represent like components throughout several views, FIG. 1 is an exterior, perspective view of a parts washer apparatus (the “parts washer”)  10 , in accordance with an embodiment of the present invention. The parts washer  10  includes a tank  12  and a basin  14 . The basin  14  includes a sink member  16  that defines a basin cavity  18 . The sink member includes a sink ledge  20  around the periphery of the inlet to the basin cavity  18 . A back-splash  22  extends upward from a rear portion of the sink ledge  20 , and a flexible faucet  24  penetrates the rear portion of the sink ledge  20  and terminates in the form of a nozzle  26 . An optional work light (not shown) extends upward from the basin and illuminates the basin cavity  18 . The tank  12  includes an optional level indicator  28  and a control panel  30 . The level indicator  28  is depicted as comprising a temperature sensitive, liquid crystal display. The control panel  30  includes an off/on switch  32 , a power indicator light  34 , a low fluid warning light  36 , and a timer switch  38 . This timer switch  38  serves to keep the circulation of the fluid limited to the time when parts are actually being washed. Studies of parts washing operators cleaning a variety of parts containing varying amount of soil indicated that a four minute time interval allows the flow to run sufficiently to clean about eight-five percent of all parts. Longer flow intervals, if required, are accomplished by reactivating the run switch. 
     FIG. 2 is a cut-away, perspective, exploded view of certain components of the parts washer  10 , in accordance with the present invention. A lower portion of the tank  12 , and components associated therewith, and the faucet  24  are cut-away in FIG.  2 . The tank  12  includes tank walls  42  that define a tank cavity  44  therebetween. The tank  12  further includes a tank lip  46  that extends around the periphery of the inlet to the tank cavity  44 . The sink member  16  includes sink walls  48  extending downward from the sink ledge  20  to a bottom panel  50  that defines a drain hole  52  therethrough. The sink walls  48  and the bottom panel  50  define the basin cavity  18 . The sink walls  48  further define an upper ledge  54  and a lower ledge  56 . Each of the ledges  54 ,  56  encircle the basin cavity  18  and include four segments that together define a rectangular shape. Each edge of a planar, rectangular support grid  58  rests upon a segment of the lower ledge  56  such that the support grid  58  partitions the basin cavity. A rectangular filter pad  60  rests upon and covers the support grid  58 . Each edge of a generally planar, rectangular false bottom member  62  rests upon a segment of the upper ledge  54  such that the false bottom member  62  also partitions the basin cavity  18  and is disposed above the support grid  58 . The false bottom member is preferably unitary, defines a drain hole  64  therethrough and includes an upwardly protruding lip around the periphery thereof. A strainer (not shown) is defined within the drain hole  64 . A pair of supplemental drain holes  70  are defined through the rear sink walls  48  just above the filter pad  60 . This embodiment comprising the false bottom member  62 , the filter pad  60 , the filter support grid  58 , and drain holes  64 ,  52 ,  70 , serves to limit evaporative losses caused by the elevated temperature of the cleaning fluid. 
     FIG. 3 is a front, vertical cross-sectional, cut-away view of the parts washer  10 , wherein certain portions of the parts washer are, for explanatory purposes, not cross-sectioned or cut-away. FIG. 3 represents each of the mechanical components (i.e. the hardware, or “parts washer”  10  as herein described), the fluid component (represented by a cleaning fluid  72 ), and the biological component (not seen) living within the cleaning fluid  72 . As depicted in FIG. 3, the periphery of the false bottom member  62  preferably snugly contacts the sink walls  48 . The tank cavity  44  is preferably partially filled with a cleaning fluid  72 . A submersible pump  73  is disposed within the tank cavity  44 . When pump  73  is operating, it draws the cleaning fluid  72  from the bottom region of the tank cavity  44  and discharges the cleaning fluid  72  into a conduit  74 . The conduit  74  is connected to and discharges into a base (not shown) of the faucet  24 , whereby the fluid discharges from the nozzle  26 . The parts washer  10  is preferably further equipped with optional cleaning accessories (not shown) such as a fountain brush (not shown) that is in fluid communication with the conduit  74 . A heater  76 , that is controlled by a thermostat  75 , selectively heats the cleaning fluid  72 , and the heater  76  is acceptably in the form of an electric heating element that extends from the control panel  30  into the depths of the tank cavity  44 . A level probe monitors the depth of the cleaning fluid  72 , and the level probe is acceptably in the form of a float actuated electric switch  78  that includes a magnet equipped float  80 . A lip  82  extends around the periphery of the sink ledge  20  forward of the back-splash  22 . The lip  82  and back-splash  22  seek to keep cleaning fluid from dripping over the edges of the sink ledge  20 . In accordance with a preferred construction of the present invention, much of the parts washer  10  is acceptably constructed from high density polyethylene. In addition, the sink walls  48 , bottom panel  50 , upper ledge  54 , lower ledge  56 , sink ledge  20 , and back-splash  22 , are preferably formed as a single, molded, unitary piece. 
     Optionally, the apparatus may be equipped with a tank  12  containing a pre-treatment compartment. This compartment receives fluid pumped from the bottom region of the tank cavity  44 . By holding this fluid in the proper environment for as long as needed to virtually eliminate oil and grease, this compartment allows discharge of waste into publicly operated treatment facilities. 
     The biological component is preferably in the form of microorganisms that biodegrade organic compounds such as, hydrocarbons, oils, greases, petroleum by-products, creolates, and other carbon based compositions. Microorganism which degrade other carbon based compositions such as the long-chain polymers compounds found in structural plastics such as the polyolefins, styrenes, neoprenes, and the like are not suitable if the physical structure of the parts washer or of parts being washed is degradable by the microorganisms. The microorganisms generally convert hydrocarbon compounds and chlorinated solvents into elements of water, carbon dioxide and other digestion products. Additionally, the microorganisms are preferably nonpathogenic. Suitable microorganisms include those from the genera Bacillus, Micrococcus, Acinetobacter, Rhodococcus, Nocardia, Flavobacterium, Saccharomyces, Candida and White Rot Fungus. Suitable species are well known and reported in the art. The microorganisms are optionally employed in combination with nitrifying or dinitrifying bacteria, phosphate solubilizing strains of microorganisms, bio-emulsifier producing strains of microorganisms, and strains of microorganisms which produce growth factors such as, B-vitamins. 
     The microorganisms are preferably subjected to a preservation technique in an effort to ensure their viability in the field and their resistance to environmental shock. For example, nutrient and buffer components such as, agar, and water soluble adhesives such as gum are preferably mixed with the microorganisms to promote stability of the microorganisms prior to mixing the microorganisms with a carrier. The carrier is composed of inert and nutrient organic materials that preserve and protect the microorganisms during storage and transportation. Suitable microorganisms are available from ABS Inc. of Duluth, Ga. as, for example, Part Number PWM-25 or from Louisiana Remediation as LRC-1. 
     The filter pad  60  functions as a vehicle for bringing the microorganisms into contact with the cleaning fluid  72 . The filter pad  60  is constructed from cotton, cellulose, polyolefin fibers, polyester fibers, fiberglass, or the like. Additionally, the filter pad  60  is constructed from combinations of such components. Further, the filter pad  60  is generally a 10 micron filter or larger. Microorganisms are attached to the filter pad  60  with an encapsulating agent  84  (FIG. 4) that is water soluble and releases the microorganisms when the cleaning fluid  72  is introduced to the filter pad  60 , as discussed below. An adhesive suitable for this purpose is 3M Super 77 adhesive. 
     Referring to FIG. 4, which is a perspective, cut-away view of the filter pad in accordance with the present invention, the filter pad  60  includes a layer  86  of inert material, that is disposed below a layer  88  of micron-rated filter media. A suitable inert material is fiberglass. The micron rated material is preferably a material that does not have an affinity for hydrocarbons such as, for example polyester. The microorganisms, the components mixed therewith as discussed above, and the adhering agent  84  are preferably sandwiched between the layers  86 ,  88  of the filter pad  60 . A portion of the layer  88  is cut-away for explanatory purposes in FIG. 4 such that the adhering agent  84  is seen. After the microorganisms are attached to the filter pad  60 , the filter pad  60  is then acceptably stored until its usage within the parts washer  10  is desired. In accordance with an embodiment of the present invention, the microorganisms are added directly to the cleaning fluid  72  without being initially attached to the filter pad  60 . Thus, the filter pad  60  functions, as both a mechanical filter (i.e., straining particulate matter from the fluid  72 ) and as an initial transport medium for the microorganisms, or the filter pad  60  functions solely as a mechanical filter. 
     The cleaning fluid  72  is compatible with (i.e., non-toxic to) the microorganisms such that the microorganisms are capable of living within the cleaning fluid  72 . Additionally, the cleaning fluid  72  tends to separate organic waste from parts washed in the basin  14 , as will be discussed in greater detail below. A suitable cleaning fluid  72 , for example, is a mixture of pH neutral emulsifiers and surfactants containing no volatile organic compounds, phosphates, formaldehyde, biocides, or other toxic materials. The emulsifier and surfactants are blended in liquid form to produce a biodegradable, non-toxic, non-caustic, non-flammable oil dispersant cleaner and degreaser. In addition the cleaning fluid  72  preferably contains no known carcinogens, no Occupational Safety and Health Act (OSHA) or Department of Transportation (DOT) regulated chemicals, no ingredients requiring Superfund Amendments and Reauthorization Act Title III reporting (SARA Title III), no Solid Waste Disposal Act as amended by the Resources and Conservation Recovery Act of 1976 as amended, 42 USC Section 6901 et seq. (RCRA), and no items on the Comprehensive Environmental Response, Compensation and Liabilities Act (CERCLA) hazardous substance list. In an illustrative embodiment, the exemplary cleaning fluid  72  is a free flowing liquid with a specific gravity of 1.083, a slight pleasant odor, no flash point, a boiling point of 210 degrees Fahrenheit, a pH of approximately seven, and is infinitely soluble in water. A suitable cleaning fluid is available from Warren Chemical Corporation of Robert, La. as Sea Wash 7 (Solvent #5 in Table 1) or Safeworld Products SW-2. 
     Referring further to FIG. 3, in operation, the pump  73 , conduit  74 , and faucet  24  circulate cleaning fluid  72  from the depths of the tank cavity  44  to the basin  18  where parts cleaning takes place. The false bottom member  62  is preferably sufficiently sturdy and well supported such that a variety of parts are capable of being placed thereon for cleaning. In an embodiment, cleaning fluid  72  flows out of the nozzle  26  and the part being washed is oriented within the stream of cleaning fluid  72  exiting the nozzle  26 . The cleaning fluid  72  separates organic waste from the part being washed, and then the cleaning fluid  72 , along with the organic waste and any small particulate washed from the part, flows by gravity through the drain hole  64  and the strainer (not shown) associated therewith. The strainer will, of course, keep certain objects from passing through the drain hole  64 . The cleaning fluid  72 , organic waste, and remaining matter then encounter the filter pad  60 . Subsequently, the fluid  72  and the organic contaminants pass through the support grid  58 , and drain hole  52  to deposit into the tank cavity  44 . Should flow through the filter pad  60  become obstructed, flow will divert through the pair of supplemental drain holes  70  defined through the rear sink wall  48  just above the filter pad  60 . The filter pad  60  functions is to trap the particulate matter and allow the organic contaminants and cleaning fluid  72  to pass therethrough. Because the filter pad  60  does not collect the organic contaminants, it is capable of being disposed of as solid waste. If the filter pad  60  is new or relatively new such that all of the microorganisms have not been previously released therefrom, the cleaning fluid  72  releases the dormant microorganisms attached to the filter pad  60 , and the released microorganisms flow with the cleaning fluid  72  and organic contaminants through the drain hole  52  into the tank cavity  44 . Within the tank cavity  44 , a large percentage of the microorganisms and organic contaminants will tend to accumulate proximate to the surface of the cleaning fluid  72  such that a large portion of the biodegradation takes place proximate to the surface of the cleaning fluid  72 . This forms a vapor barrier that tends to minimize the evaporation of the cleaning fluid  72 . If living microorganisms are not present in the parts washer  10 , increasing amounts of organic waste will accumulate toward the surface of the cleaning fluid  72  in the tank cavity  44 , and this condition is indicative of the need to replenish the microorganisms. However, if the parts washer  10  is used for normal parts cleaning, it should not be necessary to add new microorganisms to the cleaning fluid  72  of the parts washer  10 . Nonetheless, by virtue of the fact that the filter pad  60  is the vehicle for adding microorganisms to the cleaning fluid  72 , as discussed above, microorganisms are added to the cleaning fluid  72  each time a new filter pad  60  is added to the parts washer  10 , as discussed in greater detail below. By virtue of the microorganisms digesting the organic waste within the tank  12 , the cleaning fluid  72  is “recirculated” within the parts washer  10 , whereby the cleaning fluid  72  has the potential to last for extended periods of time. It is likely, however, that some cleaning fluid  72  replenishment will be required, however, to make up for evaporative and “drag-out” losses incurred as parts are removed from the basin cavity  18  in wet condition. Furthermore, by virtue of the cooperative effect of the filter pad  60  (removing particulate matter) and the microorganisms (digesting organic waste), the tank is, potentially, seldom in need of “dredging” to remove waste. 
     Referring back to FIGS. 1 and 3, when the off/on switch  32  is in the on position, electricity is supplied to circuitry (not shown) which is housed within the control panel  30  by way of a conventional power cord (not shown), and the indicator light  34  is illuminated. After the off/on switch  32  is in the “on” position, the circuitry, in combination with the thermostat  75 , activates and deactivates the heater  76 . While the thermostat  75  senses that the temperature of the cleaning fluid  72  within the tank cavity  44  is below a desired temperature, the heater  76  is on, and while the thermostat  75  senses that the temperature of the cleaning fluid  72  is at or above the desired temperature, the heater  76  is off. The cleaning fluid  72  is preferably maintained in a temperature range which supports the lives of the particular microorganisms employed within the parts washer  10 . The temperature is preferably maintained in the mesophilic range of approximately 75° to 115° Fahrenheit. The float actuated electric switch  78  also controls the operation of the heater  76 . When the magnet equipped float  80  drops downward due to a low level of the cleaning fluid  72 , the switch  78  is actuated which, in combination with the circuitry, disables the heater  76  and causes the low level warning light  36  to illuminate. Operation of the pump  73  is controlled by the timer switch  38 . A user can manually actuate the timer switch  38  which, in combination with the circuitry, causes the pump  73  to operate and automatically cut off after a certain period of time. In accordance with an alternative embodiment of the present invention, an additional switch (not shown) is provided that overrides the timer switch  38  such that the pump  73  will remain running as long as the additional switch is “on”. 
     Referring back to FIGS. 2 and 3, the parts washer  10  is designed to provide easy access to the filter pad  60 . Access is obtained by simply lifting the false bottom member  62  out of the basin cavity  18 . There is generally no restrictive engagement between any components that are depicted as exploded away from each other in FIG. 2, whereby the components of the parts washer  10  are readily accessible. 
     While certain of the embodiments of the present invention have been disclosed herein, other embodiments of the apparatus and methods of the present invention will suggest themselves to persons skilled in the art in view of this disclosure and the example below. 
     EXAMPLE 
     Ability of Invention to Clean Objects 
     Preliminary screening compared the washing ability of candidate cleaning fluids to mineral spirits. Two surfactant based cleaning fluids (also termed “fluids” or “solvents” herein) were preferred as a result. These two (Solvent #2 and #5 Table 1, were further tested for their ability to maintain viability of microorganisms suitable for biodegrading organic wastes in objects to be cleaned by the system, method and compositions of the present invention. Less preferred solvents were unable to clean substantially as well as mineral spirits. Tests were conducted using scrap parts obtained from auto repair shops (sites G, K, S, W, U in Table 1). 
     The cleaning (washing) effect of solvents alone was tested in 5 sites over several months wherein the solvents were used for washing parts in the routine course of business. Each solvent was tested over a period of several weeks to test efficacy of cleaning. Solvent #5 is Sea Wash 7. The build up of concentration of oil and grease was noted to rise steadily during the test period to the levels indicated. One liter samples of the fluid were removed at regular intervals and tested at an EPA certified testing laboratory to determine parts per million (ppm) of organic waste and particulate matter. Table la presents summary values (ppm) for two candidate solvents used in these tests, and the average ppm over the 5 sites. 
     Table 1a presents results of a compilation of data resulting from trials of the two cleaning fluids that gave the best results when tested prior to the introduction of microorganisms. Both solvents are water-based, non-toxic, surfactants. 
     Based on the tests comparing the solvents to the cleaning ability of mineral spirits and on the results in Table 1a, solvent #5 (Sea Wash 7) was selected to test with microorganisms. The same procedure used to generate Table 1a, was used, that is, solvent #5 and microorganisms were used to clean parts as a routine part of business at the same 5 sites. Approximately 7×10 9  colony forming units were affixed to a filter of dimensions of approximately 12×21 inches. Results in ppm of tests on one liter samples over time, show a dramatic effect of microorganisms on reducing the ppm. 
     Upon introducing microorganisms, the oil and grease concentrations dropped dramatically to the levels indicted in Table 1b. Laboratory tests indicated that it is possible to virtually eliminate oil and grease by continuing to circulate, aerate, and add microorganisms in fluid removed from use in parts washing. This suggested a compartment of the washing system that could be used to treat fluid and recirculate it to the compartment wherein objects are being washed. 
     FIG. 5 shows a bar graph of the average ppm and standard deviation for solvent #5 alone compared to solvent #5 with microorganisms. FIG. 6 illustrates the steady state reached in a system of the present invention as determined by ppm of oil and grease detected by EPA criteria. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
             
               
             
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 
               
               
                   
               
               
                 OIL/GREASE STUDY — FIELD TEST SI 
               
               
                   
               
             
             
               
                 Table 1a 
               
               
                 DATA PRIOR TO INTRODUCTION OF MICROORGANISMS 
               
             
          
           
               
                   
                 OIL AND GREASE (ppm) 
                   
               
             
          
           
               
                   
                 SITE G 
                 SITE N 
                 SITE S 
                 SITE W 
                 SITE U 
                 Averages 
               
               
                   
               
               
                 Solvent #2 
                 7,000 
                 14,000 
                 20,000 
                 15,000 
                 19,000 
                 15,000 
               
               
                 Solvent #5 
                 7,300 
                 16,000 
                 24,000 
                 15,000 
                   
                 15,575 
               
               
                 SITE AVE 
                 7,150 
                 15,000 
                 22,000 
                 15,000 
                 19,000 
                 15,288 
               
               
                   
               
             
          
           
               
                 Table 1b 
               
               
                 WITH MICROORGANISMS 
               
             
          
           
               
                 1994 
                 OIL AND GREASE (ppm) 
                   
               
             
          
           
               
                 MO DAY 
                 SITE G 
                 SITE N 
                 SITE S 
                 SITE W 
                 SITE U 
                 Averages 
               
               
                   
               
               
                 5/2 
                 1,000 
                 2,500 
                   
                 2,000 
                 1,800 
                 1,825 
               
               
                 5/9 
                 590 
                   
                   
                 1,650 
                 830 
                 1,023 
               
               
                 5/16 
                 1,100 
                 1,300 
                   
                 1,600 
                 1,300 
                 1,325 
               
               
                 5/17 
                   
                   
                   
                 2,400 
                   
                 2,400 
               
               
                 5/23 
                 720 
                 670 
                   
                 1,600 
                 1,300 
                 1,073 
               
               
                 5/31 
                 920 
                 1,700 
                   
                 1,500 
                 1,000 
                 1,280 
               
               
                 6/8 
                 1,300 
                 2,000 
                   
                 1,500 
                 870 
                 1,418 
               
               
                 6/15 
                 760 
                 1,400 
                   
                   
                   
                 1,080 
               
               
                 6/22 
                 410 
                 610 
                   
                 1,100 
                 960 
                 770 
               
               
                 6/29 
                 1,200 
                 2,200 
                 1,900 
                 320 
                 1,600 
                 1,444 
               
               
                 7/6 
                 710 
                   
                 1,900 
                 730 
                 1,500 
                 1,210 
               
               
                 7/13 
                 1,800 
                 1,200 
                 2,800 
                 970 
                   
                 1,693 
               
               
                 7/21 
                 1,100 
                 1,300 
                   
                 310 
                 400 
                 778 
               
               
                 7/27 
                 1,100 
                 1,600 
                   
                 860 
                 910 
                 1,118 
               
               
                 8/3 
                 2,980 
                 1,210 
                 1,320 
                 570 
                 350 
                 1,286 
               
               
                 8/10 
                 3.800 
                 980 
                 4,500 
                 400 
                 1,100 
                 2,156 
               
               
                 8/17 
                 2,500 
                 1,100 
                 1,400 
                 650 
                 3,300 
                 1,790 
               
               
                 8/24 
                 1,500 
                 3,300 
                 1,400 
                 1,300 
                 2,200 
                 1,940 
               
               
                 9/2 
                 1,900 
                 2,000 
                 930 
                 3,200 
                 590 
                 1,724 
               
               
                 9/16 
                 1,390 
                 1,290 
                 540 
                   
                 730 
                 988 
               
               
                 TOTAL ppm 
                 26,780 
                 26,360 
                 16,690 
                 22,660 
                 20,740 
               
               
                 No of Tests 
                 19 
                 18 
                 10 
                 19 
                 18 
                 84 
               
               
                 TOTAL ppm 
                 26,780 
                 26,360 
                 16,690 
                 22,660 
                 20,740 
                 113,230 
               
               
                 AVERAGE 
                 1,409 
                 1,464 
                 1,669 
                 1,193 
                 1,152 
                 1,348 
               
               
                   
               
               
                 KEY:  
               
               
                 SITE G: General automotive repair shop  
               
               
                 SITE N: Engine rebuilder  
               
               
                 SITE S: Truck repair facility — utility company  
               
               
                 SITE W: Brake repair shop  
               
               
                 SITE U: Transmission repair facility