Abstract:
A system for handling effluent from a film processor. A transportable holding tank is attached to the film processor using quick-disconnect fittings, and accepts effluent discharged from the film processor by gravity. The holding tank is uncoupled from the film processor and coupled to a receiving station with quick-disconnect fittings similar to those on the film processor. The effluent is pumped into the receiving station. The system is designed to minimize exposure to film processing chemicals, and handles parallel segregated streams of silver-bearing and non silver-bearing effluent.

Description:
FIELD OF THE INVENTION 
     The invention relates to a system for handling effluent such as film processor effluent, and in particular to a system for discontinuously removing such effluent while minimizing unintended spillage of the effluent. 
     BACKGROUND OF THE INVENTION 
     In chemical processing, and in particular the processing of photographic film such as that exemplified by the C41 process for silver halide films, the developing process releases silver from the films, leading to a liquid chemical effluent stream rich in silver which is classified as a hazardous material. This effluent stream must be collected and processed to remove the silver or collected and hauled away. Silver must be recovered from the effluent for both environmental and economic reasons. 
     There are 3 primary systems used today for dealing with effluent from a film processor: 
     (1) A hard-plumbed system to carry an effluent stream to a centralized effluent collection and/or processing point. 
     (2) A soft-plumbed system to carry the effluent stream to a nearby collection point. The collection container is then carried to a centralized effluent collection and/or processing location. 
     (3) A system of on-board holding tanks or containers mounted on the film processor. The tanks must be drained periodically. Typically this draining process consists of installing a temporary drain hose, actuating a manual drain valve and collecting the effluent in an open container. This container is then carried to a centralized effluent collection and/or processing location. 
     All three systems have shortcomings. While system 1 is operationally ideal, it requires expensive site facility modifications. It is well suited to high volume operations for which the cost of installation is most easily justified. However, it is less suitable for smaller operations. Systems 2 and 3 utilize an “open container” silver recovery unit (SRU) where the effluent is simply poured into an SRU holding tank. These systems can become messy since the containers can be overfilled and spill. Even when no overfilling occurs, systems 2 and 3 can expose an operator to hazardous materials. Also, unintentional introduction of inappropriate liquids such as non-silver bearing effluent (developer) or cleaning supplies or other industrial liquids will damage the SRU. Finally, effluent which contains silver is a potential hazard if allowed to enter a sewer system. 
     Therefore, there is a need for an inexpensive system of handling silver-bearing effluent from a film processor such that the silver-bearing effluent is isolated thereby reducing risk of exposure to untreated effluent. 
     SUMMARY OF THE INVENTION 
     An effluent handling system of the invention includes a holding tank coupled through quick-disconnect fittings to an on-board effluent reservoir on a film processor. The holding tank receives effluent from the effluent reservoir, after which the holding tank and the effluent reservoir are uncoupled. The quick-disconnect fittings are self-sealing, that is, while permitting passage of fluid when coupled, they substantially preclude passage of fluid when uncoupled. The holding tank is transferred to a receiving station whereto it is similarly coupled, and effluent is discharged from the holding tank to the receiving station. The holding tank is then uncoupled from the receiving station and is available for recoupling to the effluent reservoir when required. The invention provides a simple connection between the holding tank and either the effluent reservoir or the receiving station, which substantially precludes unintended leakage or spillage of effluent from the system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic top view of an effluent handling system showing a holding tank coupled to a film processor. 
     FIG. 2 is the view of FIG. 1, with the effluent handling system with the holding tank uncoupled from the film processor. 
     FIG. 3 is a front perspective view of a holding tank in a first embodiment for receiving spent photographic processing fluids from a film processor. 
     FIG. 4 is a rear perspective view of the holding tank. 
     FIG. 5 is a schematic side view of the holding tank and the film processor in a coupled position. 
     FIG. 6 is a schematic side view of the holding tank and the film processor in an uncoupled position, the holding tank being partially cut away to show a pump. 
     FIG. 7 is a schematic side view showing detail of the holding tank and the film processor in the coupled position. 
     FIG. 8 is a schematic side view showing detail of the holding tank and the film processor in the uncoupled position. 
     FIG. 9 is a semi-schematic perspective view of a portion of the film processor in a second embodiment of the invention. 
     FIG. 10 is a schematic top view of the holding tank coupled to a receiving station. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In wet photographic processing, an effluent solution is generated which must be removed and treated before final disposal. A film processor  110  such as one that handles the widely used C41 process for silver halide films has two working tanks  112 . The film enters one of the working tanks  112  which has developing solution, and is then rinsed and passes into the other working tank  112  containing fixing solution. 
     The working tanks  112  are replenished as the processor is used. Every 1 to 15 meters of film, fresh concentrated processing solutions and water are added, and spent solutions spill over into on-board effluent reservoirs  114 . 
     Of the spent solutions, the developer is free of silver, and the fixing solution is silver-rich. For both economic and environmental reasons, silver must be recovered from the spent fixing solution. However, any presence of developer would interfere with silver recovery from the fixing solution. Therefore, any system of silver recovery must maintain segregation of the two solutions. 
     An effluent handling system  100  of the present invention, shown schematically in FIGS. 1 and 2, is intended for transferring spent solution from the effluent reservoir  114  to a receiving station  170  which can for example include a silver recovery unit (SRU) or some precursor thereto. In particular, the invention is intended to substantially preclude any unintended leakage or spillage of effluent. 
     The invention includes in particular a holding tank  130  which receives effluent from the effluent reservoir  114 , as shown in a first embodiment in FIGS. 3 and 4. The holding tank  130  has a housing  132  and two chambers  134 , one for developer and one for fixer. While segregated at all times, the developer and fixer effluents follow parallel paths through the system  100 . The holding tank  130  includes a base  136  with supports  138  such as wheels, castors or the like to provide mobility. 
     The holding tank  130  can be removably coupled to the effluent reservoir  114  by means of fixtures  160 , each of which has a first fitting  162  disposed on the holding tank  130  and a second fitting  164  disposed on the film processor  110 . Preferably the fittings are male and female quick disconnect fittings, such as those supplied by the Colder Products Company, part numbers HFCD16812 and HFCD22812, either of which could be used as the first and second fitting. For the purposes of this description, it is understood that the first fittings  162  are male quick-disconnect fittings, and the second fittings  164  are the corresponding female quick-disconnect fittings with a release element such as a spring loaded release button  166 . Thus, the button  166  is on the film processor  110 . 
     Each first fitting  162  is connected with one of the chambers  134 . Each second fitting  164  is disposed near the bottom of the corresponding effluent reservoir  114  so that substantially the entire volume of the effluent reservoir can be emptied by gravity. To allow effectively complete transfer by gravity of the effluent from the effluent reservoir  114 , the chambers  134  must be at a lower level than the effluent reservoir  114 . The first fittings  162  and the second fittings  164  are aligned so that when the holding tank  130  and the film processor  110  are brought into proximity, the fixtures  160  corresponding with the developing and fixing solution effluents can be readily engaged. It will be apparent that each first fitting  162  is near the top of the corresponding chamber  134 . 
     The holding tank  130  has a projection  140  jutting beyond the general lines of the housing  132 . The projection  140  defines a first recess  141  within which the first fittings  162  are substantially located. The film processor  110  has a casing  118 , wherein is provided a second recess  120 . The second fittings  164  are generally within the second recess  120 , that is they do not project significantly outside the general lines of the casing  118 . Preferably, the second recess  120  of the film processor  110  and the projection  140  of the holding tank  130  are correspondingly tapered so as to facilitate their alignment and the coupling of the fixtures  160 . 
     When the fixtures  160  are coupled, there is fluid communication between the effluent reservoir  114  and the holding tank  130 . The fixtures  160  are self-sealing; that is, passage of fluid is substantially precluded when the first and second fittings  162  and  164  are uncoupled. If the fixtures  160  were not self-sealing, separate shutoffs would be provided. 
     Engaging the first and second fittings  162  and  164  causes the button  166  to move until the first and second fittings  162  and  164  are properly located, at which point the button  166  reverts to a retaining position so that the first and second fittings  162  and  164  snap together. 
     In conventional use, the fixtures  160  can be uncoupled by simultaneously depressing the button  166  and pulling apart the first and second fittings  162  and  164 . However, in the present invention, the proximity of the holding tank  130  and the film processor  110  renders access to the button  166  difficult. Therefore, a latch mechanism is provided. 
     The first embodiment has a control element such as a spring-loaded lever  142  which is pivotally attached to the holding tank  130 , as shown schematically in FIGS. 7 and 8. The lever  142  has a generally horizontal idle position, and an angled active position. The lever  142  is normally retained in the idle position by force from a latch spring (not shown), but is movable to the active position against the opposition of the latch spring. At one end, corresponding with the front side of the holding tank  130 , the lever  142  has two downwardly directed prongs  144 , each aligned with one of the corresponding fixtures  160 . The opposite end of the lever  142  projects through an opening  146  in the housing  132 , allowing the lever to be accessed from the rear side of the holding tank  130 . 
     With the fixtures  160  coupled and the lever  142  in the idle position, the prongs  144  are directly above but spaced apart from the buttons  166 . When the lever  142  is moved to the active position, the prongs  144  simultaneously depress both buttons  166 , thus allowing the fixtures  160  to be uncoupled. Note that in the first embodiment, the buttons  166  are on the film processor  110  and the lever  142  is on the holding tank  130 . 
     In a second embodiment, shown in FIG. 9, the control element is a handle  122  disposed substantially within the second recess  120  of the film processor  110  directly above the buttons  166 . The handle  122  abuts the upper ends of a pair of rods  124 , each slidably mounted in a holder  126  attached to the casing  118 . The rods  124  are spring loaded to retain the handle  122  in an upper orientation, which is the idle position as illustrated in FIG.  9 . When actuated, the handle  122  forces down the rods  124  so that they contact and depress the buttons  166 , and allow coupled fixtures  160  to be pulled apart. 
     It is understood that the control elements could be configured accordingly if the release element were disposed on the holding tank  130  rather than on the film processor  110 . 
     FIG. 10, the system  100  shows the holding tank  130  coupled to the receiving station  170 , which can include a silver recovery unit (SRU) or can be a pumping station that fills certified effluent transport drums that can be hauled away to another site for silver recovery. The receiving station  170  has a third recess  172  and third fittings  174  that are identical to the second fittings  164  and can therefore accept the first fittings  162  in the same way. Unless the receiving station  170  is at a generally lower level than the holding tank  130 , gravity cannot be relied on to provide drainage. Therefore, effluent needs to be pumped out of the holding tank  130 . Depending on the nature of the receiving station  170 , the holding tank  130  has a pump  148  as indicated in FIG. 6, or there may be a pump at the receiving station  170 . The receiving station  170  has separate compartments  176  for silver and non-silver bearing effluent. 
     The relative volumes of the working tanks  112 , effluent reservoir  114 , and holding tank  130  are important. Clearly, each chamber  134  must have a greater capacity than the corresponding effluent reservoir  114  to preclude overfilling. Preferably, the chamber  134  has a greater capacity than the corresponding effluent reservoir  114  and working tank  112  combined. 
     While the holding tank  130  has been described as having a wheeled base  136 , other configurations may be envisaged. For example, the holding tank  130  could be suspended from a hoist mechanism configured to move along an overhead rail. In this case, the holding tank  130  could be moved both horizontally and vertically. 
     It can also be envisaged that the holding tank  130  could have additional fittings identical to the first fittings  162  near the bottom of the chambers  134 . This would allow effluent to drain from the holding tank  130  to the receiving station  170  under gravity. Of course, it would then be necessary either to elevate the holding tank  130  or locate the receiving station  170  at a lower level. 
     The holding tank  130  of the invention is predominantly constituted by the housing  132 , which is a molded plastic such as high density polyethylene. The fixtures  160  are of plastic coated stainless steel. 
     The invention is used as follows. When an operator determines that the either effluent reservoir  114  is full (as indicated for example by a level sensor), the operator wheels the holding tank into proximity with the film processor  110 , and with the aid of the tapered projection  140 , aligns the corresponding first and second fittings  162  and  164 . The operator then pushes the holding tank  130  further towards the film processor  110  so that the fixtures  160  snap together. The coupling of the fixtures  160  causes internal valves to open, thus fluidly connecting the effluent reservoir  114  and the holding tank  130 , which are configured so that the contents of the effluent reservoir  114  drain into the holding tank  130  under gravity. When drainage is complete, the operator actuates the lever  142  to depress the button  166  of each second fitting  164 , and simultaneously withdraws the holding tank  130  from the film processor  110 . The operator wheels the holding tank  130  to the receiving station  170  and couples each to the other in the same way as the holding tank  130  was preciously coupled to the film processor  110 . The pump  148  is now operated to discharge the contents of the holding tank  130  to the receiving station  170 . After completing the pumping operation, the operator uncouples the holding  130  tank from the receiving station  170  by actuating the lever  142 . The holding tank  130  is now ready for re-use. Note that in the first embodiment, the operator uses the same lever  142  as before, since it is on the holding tank. Were the second embodiment to be used, a separate control element would be provided at the receiving station  170 , identical to the handle  122  on the film processor  110 . 
     While the present system  100  is intended for handling effluent from film processing, it can also be used in the processing of photographic paper. More generally, it could be used to preclude spillage of many types of effluent, whether or not they contain silver—in fact, in a multitude of situations in which it is desired to discontinuously transfer fluid from one vessel to another while precluding significant unintended escape of fluid. 
     Various features of the present invention have been described with reference to the above embodiments. It should be understood that modification may be made without departing from the spirit and scope of the invention as represented by the following claims.