Abstract:
An apparatus for transferring effluent from photograph development systems, especially highly automated, high-volume developer systems. A silver-recovery system discharges an iron-rich solution into a tank. Developer fluid and fixer solution is mixed with the iron-rich solution in the tank to buffer its pH. A float in the tank activates a switch located outside the tank to actuate a pump for evacuating the mixed effluent from the tank for disposal. Water may be mixed under pressure with the pumped effluent to reduce clogging in effluent drainage lines due to precipitate and other and build-ups from effluent.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60/503,559, entitled Effluent Transfer Station and Drain Wash, filed on Sep. 16, 2003, and the specification thereof is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention (Technical Field)  
         [0003]     The present invention relates to systems for recovering ionic silver from effluent, especially effluent from conventional photographic film developing, and pertains specifically to an effluent transfer apparatus for flushing residues from system plumbing.  
         [0004]     2. Background Art  
         [0005]     It is known that the development of conventional photographic film results in the production of fluids containing valuable quantities of the precious metal silver. A variety of known methods and systems are used to recover silver from such fluid by-products. Typically, photographic by-product solutions are processed through a special canister where silver ions in solution are exchanged for iron ions. Silver thus can be recovered subsequently from the canister device (such devices are known in the art). The resulting fluid discharge is depleted of silver, but rich in iron. The iron-rich solution ordinarily is composed of bleach fix and stabilizers, which are mixed with developer solution to neutralize solution pH. The solution commonly is stored in an effluent tank until it is disposed down a hose for discharge into a drain for disposal.  
         [0006]     A problem is that the discharged effluent is prone to clog the drainage line, especially as residue accumulates on the walls of drain lines. This problem is particularly acute in modern, technically automated development systems; automatic development systems are increasingly efficient to use reduced quantities of water, resulting in heavier sludge-like effluents. Plus, many automated systems not only develop and print photographs; they also cut, within the machine, the photographic paper. As a result, small paper trimmings and offal find their way into the effluent stream, increasing its density and proclivity to cause drain clogs. Against this background, the present invention was developed.  
       SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)  
       [0007]     The invention is an apparatus (and corresponding method) comprising a self-cleaning effluent transfer station for use in the photographic development industry. A tank holds system by-product solution mixed with developer solution, and when the effluent level in the tank reaches a selected height, a pump is actuated to evacuate solution from the tank. After being pumped from the tank, the mixed solution can be combined and mixed with fresh water, and forcibly discharged through the ultimate drain line, thus flushing the drain line and reducing undesirable residue build-up in the drain lines.  
         [0008]     A primary object of the present invention is to provide an effluent transfer apparatus, for use in the photograph development industry, which requires considerably less maintenance than known transfer stations and techniques, and which in its preferred embodiment significantly reduces clogging in transfer station drain lines.  
         [0009]     There is provided according to the invention an apparatus for transferring effluent from a photographic development system, the system discharging a waste developer solution and a by-product solution from a silver recovery device, the apparatus comprising: a tank; an inlet for introducing the waste developer solution into the tank; a canister discharge inlet for introducing the by-product solution into the tank for mixing with the developer solution, the mixture comprising an effluent the fluid level of which rises and falls within the tank; a pump for evacuating the effluent from the tank to a drain line; a control switch outside the tank and in communication with the pump; and a float within the tank, floatable upon the effluent at the fluid level, in operative connection with the control switch. The preferred embodiment further includes the optional but preferable features of a water feed line for supplying water to the drain line; and a water control valve, in communication with the control switch, for controlling water flow through the water feed line.  
         [0010]     According to the preferred embodiment, the float signals the control switch to start the pump to begin evacuating the effluent when the fluid level rises to a first predetermined level in the tank, and the float signals the control switch to stop the pump when the fluid level falls to a second predetermined level in the tank. Preferably, the control switch opens the water control valve to start water flow (preferably under pressure) to the drain line while effluent is evacuating through the drain line, and the control switch closes the water control valve to stop water flow to the drain line when no effluent is evacuating through the drain line.  
         [0011]     Preferably, the waste developer solution inlet is disposed in a side of the tank, and the effluent fluid level is maintained at or about the height of the developer solution inlet. There preferably is a tube means (such as a rigid PVC pipe) inside the tank, connected to the canister discharge inlet, for introducing the iron-rich silver-recovery by-product solution below the effluent fluid level. Because the effluent to be transferred may be very dense and somewhat viscous, the pump should have flexible impellers.  
         [0012]     The first predetermined level mentioned above is approximately at the height of the waste developer solution inlet, and the float is movable up or down through a distance of between approximately 8″ and approximately 10″, so that the first predetermined level and the second predetermined level are separated by approximately 9″±1″.  
         [0013]     Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings:  
         [0015]      FIG. 1  is a side partial sectional view of the apparatus of the invention;  
         [0016]      FIG. 2  is an enlarged top perspective view of a portion of the apparatus seen in  FIG. 1 , showing the pump, backflow prevention valve, water control valve, float control, and associated fluid-conducting lines and tubes; and  
         [0017]      FIG. 3  is an enlarged side view of the portion of the inventive apparatus seen in  FIG. 2 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     BEST MODES FOR CARRYING OUT THE INVENTION  
       [0018]     The present invention relates to an apparatus for providing a self-cleaning effluent transfer station, particularly a transfer station used by the photographic processing industry. The apparatus according to the invention is useable in combination with a solution neutralizer tank, can be used in known containment trays, and uses municipal water to rinse discharge lines to sewer.  
         [0019]     According to the invention, there is provided an apparatus that easily pumps photographic effluent mixes that are slurry-like, and which tend to deposit tar-like and other residues in drainage lines. The apparatus provides controlled bursts of water to keep discharge plumbing, particularly effluent discharge hoses, free and clear of clogs. The inventive apparatus is particularly useful in connection with efficient development systems which generate highly concentrated, comparatively dense, effluent streams. Recent development systems generate waste streams having considerably thicker chemistry, due to increased concentrations of salts and elevated pH levels; current systems may produce effluents 30% to 40% higher in density than systems of even a few years ago.  
         [0020]     Reference is made to the drawing figures. The invention operates with a transfer station  10  having a neutralizer tank  12 . Neutralizer tank  12  receives and holds effluent solutions received from a silver recovery canister (not shown) known in the art. In one example of the invention, the tank has a capacity of approximately 3.5 gallons (U.S.). It will be understood, however, that the apparatus of the invention may be manufactured to any suitably practical size. The apparatus may be adapted in size to correspond to the effluent discharges to be managed.  
         [0021]     Silver recovery canisters discharge solutions high in iron. The tank  12  is crafted from corrosion-resistant material, such as, by way of example only, polyethylene or stainless steel. The transfer station tank has a sealing lid  21  to enclose its interior. The lid  21  also mounts certain elements of the apparatus of the invention, as described below.  
         [0022]     Iron-rich recovery by-product solution from the silver-recovery canister is discharged into the neutralizer tank  12  via the canister discharge inlet  14 . The canister discharge inlet  14  has a tube  15  extending downward into the tank  12 , so that the silver recovery by-product solution is discharged below the surface of the fluid in the tank. Thus, a feature of the apparatus is a tube means, e.g., a length of rigid PVC pipe  15 , for introducing the by-product solution proximate to the bottom of the tank  12  below the level of effluent standing in the tank, regardless of the effluent level. Introducing the iron-rich by-product solution below the effluent surface eliminates contact between ambient air and undiluted by-product solution, thus minimizing undesirable oxidation of the by-product solution. A waste developer-fixer solution also is introduced through developer inlet  18  into the tank  12 . The developer inlet preferably is in the side of the tank  12  a distance below the lid  21  as seen in  FIG. 1 .  
         [0023]     An object of the invention is to provide an effluent transfer station in which the effluent is mixed to improve its acidity (pH) level prior to discharge to drain. The by-product received from a silver-recovery canister typically has acidity in the vicinity of pH 6.5 to pH 7.0. The developer solution emitted from a typical developer system is approximately pH 8.0 to pH 10.0, while the fixer is about pH 5.5. The invention mixes developer solution with the canister by-product solution, so that the developer can buffer the by-product, resulting in a mixed effluent having a pH of approximately 7.0 to 7.5.  
         [0024]     Accordingly, the mixed effluent temporarily stored in the tank  12  consists partially of developer solution introduced into the tank  12  via the developer inlet  18 . By mixing the comparatively harsh iron-bearing by-product solution with cast-off developer, the by-product solution is diluted in the tank  12 . Preferably, a bleach fix also is mixed into the developer solution, so that the mixing of the developer-bleach solution effectively neutralizes the acidity of the mixture in the tank  12 . The mixed effluent, i.e. the mixture of recovery by-product solution with the developer-bleach solution, is temporarily retained in the tank  12  until discharged out of the tank via the outlet tube  20 .  
         [0025]     A sample port  38  preferably is provided in the tank  12  to permit sampling of the chemistry of contained effluent therein.  
         [0026]     The outlet tube  20  is connected to the inlet of an electrically powered, self-priming, fluid pump  22 . The mixed solution is pumped, by the action of pump  22 , so to be evacuated from inside the tank  12  to the pump discharge line  24 . The pump  22  is, for example, a 1.5 amp self-priming pump. The pump  22  preferably has flexible impellers to pump the denser effluents characteristic of modem development systems. A flexible impeller pump suitable to a preferred embodiment of the invention is the JABSCO® brand pump, model number 12310-0001, available from ITT Industries (Jabsco US), of Foothill Ranch, Calif., USA.  
         [0027]     A very preferable, but not critical, added feature of the invention is realized by importing clean water, such as from a municipal source, to the apparatus via the clean water feed line  26 , as seen in  FIGS. 1-3 . Clean water is supplied under pressure to the water control valve  27  mounted upon the tank  12 . When the water control valve  27  is open, water flows through valve outlet line  29  to the backflow prevention valve  30 . Backflow prevention valve  30  prevents water from flowing backward in outlet line  29  toward the feed line  26 . The prevention valve  30  thus prevents a reverse flow that otherwise could contaminate the water source and/or damage water control valve  27 .  
         [0028]     Outlet line  29  joins to the pump discharge line  24 , as with an ordinary T-fitting or the like. Water flowing out of the backflow prevention valve  30  thus is combined with mixed effluent flowing out of the pump  22  through the pump discharge line  24 . The combined fluids are then discharged to drain, for example a floor drain, via the drain line  32 .  
         [0029]     Continued reference is made to  FIGS. 1-3 . An advantage of the invention is provided by the operation of the float control switch  34 . Float control switch  34  is an electronic signaling component of conventional off-the-shelf construction that is in electrical communication with both the pump  22  and the water control valve  27 . A buoyant float  37  is free to travel vertically up and down on an inert guide rod  38  according to the fluid level  40  of the mixed effluent contained in tank  12 . Guide rod  38  is inert to the mixed solution, and thus advantageously is resistant to the adverse chemistry inside the tank  12 . The float  37  also is inert to the effluent, but is in mechanical communication with the control switch  34 , so that the float control senses the fluid level  40  of the mixed solution in the tank  12 . In the preferred embodiment, the float  37  has about eight to ten inches of travel up and down on the rod  38 . The extended range of travel permits the actuation of the control switch  34  to be regulated to minimize frequency of pumping operation while yet optimizing overall apparatus performance.  
         [0030]     The float  37  is mechanically operatively linked to the float control  24  (as by a rod linkage), and the mechanical linkage interacts magnetically and/or electrically with the control  24  at the location of the control. The introduction of any electrical current to the interior of the tank  12  thus is eliminated.  
         [0031]     Control switch  34  advantageously is located outside the tank  12 , preferably on the lid  21 , protected from the harsh chemistry within the tank  12 . Systems which place electrical components, including switches, inside the effluent tank are thus distinguished. In the present invention, no electrical components are located inside the tank, thus preventing their fouling or malfunction from harsh effluent chemistry. The control switch  34  senses the fluid level  40 , and is pre-programmed to signal the pump  22  and the water control valve  27 , when the fluid rises to a predetermined level in the tank  12 .  
         [0032]     As suggested from  FIG. 1 , the float  37  is movably situated on the rod  38  so to activate the pump  22  when the fluid level  40  is at a predetermined level, which may be approximately at the height of the developer inlet  18 . Thus, the fluid level preferably is regulated to keep the inlet  18  at or about (either modestly above or below) the maximum fluid level in the tank  12 . Similarly, when the fluid level of effluent mixture in the tank falls to a second predetermined level, the float signals the control switch  34  to stop the pump  22  to cease the evacuation of the tank.  
         [0033]     The control switch  34  also can be connected to a switch controlling the flow of solution through the canister input  14 , so that such flow is interrupted in the event of an imminent accidental overflow due to a failure elsewhere in the system, for example the pump  22 .  
         [0034]     The function of the invention, while generally apparent from the foregoing, is now described. By-product solution (from which most silver has been removed) is conveyed into the tank  12  through the canister discharge inlet  14  and rigid tube  15 . Also, waste developer solution is dumped into the interior of the tank  12  via the developer inlet  18 . The volume of developer is less than the volume of by-product solution, but the former significantly dilutes the latter; the developer solution also may contain a pH-neutralizer, such as bleach. The developer and by-product solutions mix inside the tank, and the level of the mixed effluent rises in the tank. The fluid level  40  is sensed and monitored by the float  37  which floats on the mixture and communicates to the control switch  34 . When the mixed solution obtains a pre-determined level, the control switch  34  signals the pump  22  and the water control valve  27  to start the pump and open the control valve. The pump  22  evacuates mixed effluent from the tank  12  through the outlet tube  20  and the discharge line  24 , while the pressurized line  26  supplies fresh water through the control valve  27  and the backflow check valve  30 . The mixed solution and the clean water combine in the vicinity of the junction of the outlet line  29  and discharge line  24 . The discharge line  32  thus is flushed out with a burst of high-velocity, diluted effluent (bearing precipitated iron). The flow out the drain line  32  continues until the fluid level  40  in the tank  12  recedes to a predetermined minimum, at which time the float  37  and control switch  34  signals the pump  22  to turn off, and the water control valve  27  to close.  
         [0035]     The water mixed with the slurry-like mixed solution dilutes the combined flow to assure that the final effluent flow past a conventional trap (not shown) somewhere along the drain line  32 . The pumped effluent scrubs the interior walls of the drain line  32 . Further, the float control can be set to regulate a low fluid level  40 , so that the tank is maintained mostly empty, if desired. Also, an overflow alarm (not shown) can be connected to the control switch  34 , so that if the pump  22  fails, operators can be notified before catastrophic overflow of the tank  12  occurs; further, if the fluid level  40  exceeds the maximum “alarm” level due to pump failure but continued flow through the input lines  14  and/or  18 , the float control  34  can be programmed to signal to automatically turn off the pumps supplying solutions through the inlet lines  14 ,  18 .  
         [0036]     A principal advantage of the invention, however, is that the pressurized flow of clean water into the system, via the outlet line  29 , flushes drainage plumbing and keeps drains clear of deleterious residue build-up and clogging.  
         [0037]     The invention is favorably distinguished from transfer stations that introduce fresh dilution water into the effluent tank. In the invention, dilution/flushing water is introduced outside and “downstream” of the effluent holding tank, eliminating the possibility of accidentally overflowing the tank with fresh water. The invention also is distinguished from systems employing pressure eductors to draw fluid from the tank. In some effluent transfer systems, the relative reduction in pressure (i.e. a Venturi effect) resulting from liquid flowing rapidly through the straight course of a T-fitting is used to suck fluid through the branch of the T-fitting into the liquid flow. The present invention offers improved reliability over pressure eductor-type systems.  
         [0038]     Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.