Abstract:
An apparatus for discharging effluent from a photographic process, such as developing liquid to a drain. The effluent can be, for example, de-silvered, spent fixer liquid, and spent developer liquid, which if mixed together, particularly in the presence of oxygen, form a solid iron oxide precipitate which becomes a sludge and eventually clogs pipes and drains. The apparatus includes two separate reservoirs for holding the liquids and two separate pumps for pumping the liquids to a drain, while reducing the risk of clogging in the pipes and drain from precipitate formation.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to effluent discharge systems for use in photographic processing and, more particularly, to discharging spent fixer and developer liquids.  
         BACKGROUND OF THE INVENTION  
         [0002]    Various liquid compositions are employed in the commercial development of black and white and colour photographs. For example, a developer liquid is used to develop an exposed film and a fixer liquid is used to fix the developed image on the medium. The developer liquid is highly alkaline typically having a pH of 10 to 11, while the fixer liquid typically has a pH of 4.5 to 7.5. Both liquids are recycled in use until, after a certain number of cycles, their effectiveness decreases to the point where they are considered to be “spent”.  
           [0003]    During the development process, ions of silver accumulate in the fixer liquid. The silver is recovered from the fixer liquid by an exchange process which ultimately adds additional iron to the iron ions already present in the fixer liquid. When the fixer liquid is finally spent, it is non-toxic and thus may be disposed of in the municipal drainage system. This is also the case with spent developer.  
           [0004]    However, when these two fluids are mixed, ammonia is formed which acts as a breeding ground for bacteria which form a sludge sometimes referred to as “Bio-Slime”. This sludge, together with the iron oxide precipitation which occurs when the fixer is exposed to atmospheric oxygen, tends to clog hoses in the apparatus and drains, etc. While machinery and conduits can be regularly maintained, many photographic processing facilities have only a single drain leading to the municipal system, and hence mixing of these chemicals is unavoidable. Most clogging occurs in the local access to the municipal system, however, and not in the municipal system itself because, while the local access may have a conduit size of  4  inches in diameter or less, the municipal conduits are much larger and thus more resistant to clogging.  
           [0005]    In one attempt to solve the problem of drain clog, Canadian Patent No. 2,261,557 to Brunelle et al. discloses a photographic effluent discharge system in which spent fixer and developer are mixed in a holding container and then pumped via a venturi mechanism at high speed to the drain. Pumping the fixer-developer in this manner causes the precipitate in the liquid combination to be forced into the municipal drain at high speed, thereby attempting to ensure that the precipitate is not permitted to reside in the local access conduit, but rather is forced out to the larger municipal drainage conduit.  
           [0006]    The device of Brunelle et al., however, requires that the fixer and developer liquids be mixed in the holding container and sludge inevitably forms and clogs the device. Also, the piping in the device located downstream of the holding container is also exposed to the sludge and thus is susceptible to clogging and must be periodically cleaned.  
           [0007]    Accordingly, there is a need for an apparatus and method for discharging effluent from a photographic process which reduces the tendency for sludge formation and its consequent clogging effect.  
         SUMMARY OF THE INVENTION  
         [0008]    In a first aspect, the present invention provides an apparatus for discharging effluent from a photographic process, the effluent comprising at least two liquids, the apparatus comprising a first reservoir for receiving a first liquid, the first reservoir having a first evacuator for evacuating the first liquid from the first reservoir, and a second reservoir for receiving a second liquid, the second reservoir having a second evacuator for evacuating the second liquid from the second reservoir.  
           [0009]    In a second aspect, the present invention provides an apparatus for discharging effluent from a photographic process, the effluent comprising at least two liquids, the apparatus comprising a first reservoir for receiving a first liquid, the first reservoir having evacuation means for removing the first liquid from the first reservoir and transport means for transporting the removed first liquid to a drain, and a second reservoir for receiving a second liquid, the second reservoir having evacuation means for removing the second liquid from the second reservoir and transport means for transporting the removed second liquid to a drain.  
           [0010]    In a third aspect, the present invention provides a method of disposing of a first liquid and a second liquid from a photographic processing machine, the method comprising pumping the first liquid to a drain, and pumping the second liquid to a drain, the first and second liquids not being permitted to mix until in the drain. 
       
    
    
     DESCRIPTION OF THE DRAWING  
       [0011]    The present invention will now be described by way of example only, with reference to the drawings in which:  
         [0012]    [0012]FIG. 1 is a schematic view of an effluent discharging apparatus in accordance with a preferred embodiment of the present invention; and  
         [0013]    [0013]FIG. 2 is a schematic view of an effluent discharging apparatus in accordance with an alternate embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    An effluent discharging apparatus in accordance with a preferred embodiment of the present invention is shown in FIG. 1 at  100 . Apparatus  100  comprises a container or tank  48  having a floor  46 , a surrounding wall  49  and a lid  50 . A divider  47  divides tank  48  into two reservoirs  17  and  43 , respectively, which are separate and prevent contact between their respective contents, as will be described in more detail below. A volume of air  20  is above the liquid in tank  48 .  
         [0015]    Reservoir  17  holds a fixer liquid  18  which has a liquid level  86 . Reservoir  17  has a feed conduit  15  connected to a source of spent de-silvered fixer (not shown). Feed conduit  15  terminates at an inlet  14  positioned at a level  88  above floor  46 . An emergency overflow is provided at  16 . Inlet  14  is positioned at level  88  below a liquid low level  7  (described further below), to ensure that inlet  14  is always submerged in liquid  18 . When fixer liquid is exposed to atmospheric air, iron oxide precipitation occurs and, thus, to avoid a clogging of inlet  14  it is preferable to protect inlet  14  from contact with air  20  by keeping it submerged.  
         [0016]    Reservoir  17  has an outlet conduit  98  having an outlet  7  which is preferably spaced apart from floor  46  at a level  102  to minimize any interference with outlet  7  which may be caused by tank bottom  46 . Outlet conduit  98  communicates with an evacuator such as a venturi  4  in this case, via a pump inlet  94 . Venturi  4  also has a carrier liquid inlet  3  and an outlet  5 . Carrier liquid inlet  3  is connected via conduit  96  to a carrier liquid source (not shown), preferably a typical municipal water line, such line having a typical delivery pressure of about  40  psi. Interposed in conduit  96  is a solenoid valve  2 , described in more detail below. Outlet  5  communicates with a drain  24  through a discharge conduit  6 . Drain  24  is preferably a typical municipal drain access having a P-trap  26 A and a local access line  26 B which leads to the municipal drainage system (not shown).  
         [0017]    Venturi  4  is a typical fluid venturi and is sized to pump fixer liquid  18  at a high velocity and deliver the liquid to a drain, as will be described in more detail below.  
         [0018]    Reservoir  17  is instrumented with a low liquid level sensor  13  and a high liquid level sensor  12  which are operatively connected with solenoid-operated valve  2  located upstream of venturi  4  on carrier liquid conduit  96 . Also operatively connected to solenoid valve  2  is an automated timer  1 .  
         [0019]    Reservoir  43  is constructed and instrumented in a similar manner as reservoir  17 . In particular, reservoir  43  holds a developer liquid  44 , having a liquid level  90 , and has a feed conduit  41  connected to a source of spent developer (not shown). Feed conduit  41  terminates at an inlet  40  positioned at a level  92  above floor  46 . An emergency overflow is provided at  42 . Leading from reservoir  43  in an outlet conduit  108  having an outlet  33 , which is preferably spaced apart from floor  46  at a level  110 . Outlet conduit  108  communicates with an evacuator or pump  30 , a venturi  30  in this case, via a pump inlet  104 . Venturi  40  also has a carrier liquid inlet  29  and an outlet  31 . Carrier liquid inlet  29  is connected via conduit  106  to a carrier liquid source (not shown), preferably also a typical municipal water line. Venturi  4  is sized to adequately pump liquid from the disclosed apparatus at sufficient velocity to deliver the liquid to the municipal drainage system in a manner as disclosed herein. Interposed in conduit  106  is a solenoid valve  28 , described in more detail below. Outlet  31  communicates with drain  24  through a discharge conduit  46 . Reservoir  43  also has a low liquid level sensor  39  and a high liquid level sensor  38  which are operatively connected with solenoid-operated valve  28  located upstream of venturi  3  on carrier liquid conduit  106 . Also operatively connected to solenoid valve  26  is a manual override switch (not shown).  
         [0020]    In operation, liquid  18  is provided to reservoir  17  by inlet conduit  15  and rises to a level  86 . When level  86  meets or exceeds a liquid level  9  in reservoir  17 , high level sensor  12  senses the liquid level and triggers solenoid valve  2 , which in turn opens to start a flow of carrier water through conduit  96  and into venturi  4 . It will be understood that the flow of carrier water into venturi  4  causes a low pressure in the venturi, which in turn pumps liquid  18  from reservoir  17  by drawing liquid through outlet  7 , up conduit  98  and into venturi  4  to mix with the carrier water. The carrier water and liquid  18  mixture exits the venturi through exit  5  and travels via conduit  6  to drain  24  and, ultimately to the municipal drainage system.  
         [0021]    Pumping continues until level  86  drops to or below level  10 , at which time low level sensor  13  senses the liquid level  86  and sends a signal to the solenoid valve  2  to turn off the flow of carrier water and thus stop the pumping of liquid  18  from reservoir  17 . Thus, the liquid level  86  in reservoir  17  is maintained between levels  10  and  9 .  
         [0022]    If for some reason liquid level  86  rises beyond level  9  in reservoir  17 , liquid  18  will simply drain out overflow  16  once it reaches level  8 . Level  8  is lower than the level  84  of the top  82  of divider  47 .  
         [0023]    Also in the operation of apparatus  100 , liquid  44  is provided to reservoir  43  by inlet conduit  41  and rises to a level  90 . When level  90  meets or exceeds a liquid level  35  in reservoir  43 , high level sensor  38  senses the liquid level and triggers solenoid valve  28 , which in turn opens to start a flow of carrier water through conduit  106  and in into venturi  30 . The induced low pressure in the venturi pumps liquid  44  into conduit  108  from outlet  33  to venturi  30 , where it mixes with the carrier water. The carrier water and liquid  44  mixture exits the venturi through exit  31  and travels via conduit  46  to drain  24  and, ultimately to the municipal drainage system. Pumping continues until level  90  drops to or below level  36 , at which time low level sensor  39  senses the liquid level  90  and sends a signal to the solenoid valve  28  to turn off the flow of carrier water and thus stop the pumping of liquid  44  from reservoir  43 . Thus, the liquid level  80  in reservoir  43  is maintained between levels  35  and  36 . If for some reason liquid level  90  rises beyond level  35 , liquid  44  will simply drain out overflow  42  once it reaches level  34 . Level  34  is lower than level  84 .  
         [0024]    The filling and evacuation of reservoirs  17  and  43  described above may occur at the same time or at different times. Preferably, their respective operation is governed by the liquid level sensors, such that the venturis may or may not be operating at the same time, depending on the condition of each.  
         [0025]    Timer  1  is provided to permit solenoid valve  2  to be opened for a pre-selected period of time, an operation useful for the periodic purging of reservoir  17  substantially of spent fixer liquid  18 , a regular maintenance operation well-known in the art with this type of apparatus. A manual override (not shown) is provided on solenoid valve  28  to the valve to be manually opened for a periodic purge or reservoir  43 , a regular maintenance operation well-known in the art with this type of apparatus.  
         [0026]    Spent fixer liquid  18  reacts with the oxygen in the air  20  which produces iron oxide precipitate, albeit at a relatively slow rate. Thus a regular build-up of precipitate occurs in reservoir  17  over time. Purging reservoir  17  clears away the precipitate. Preferably, timer  1  is set to operate valve  2  once per day, to ensure that reservoir  17  empties at least that frequently. Alternately, timer  1  can be set to operate valve  2  at other time intervals. Preferably, to save wasting carrier liquid, timer  1  opens valve  2  for a minimum amount of time while still ensuring that reservoir  17  is evacuated down to level  102 . As well, since timer  1  will usually be used when apparatus  100  will be unsupervised for relatively long periods of time by personnel, minimizing the amount of time that timer  1  actuates venturi  4  minimizes any damage to the photographic processing facilities if there is a problem with apparatus  100  for some reason, such as discharge hose  6  or  46  becoming disconnected from drain  24 .  
         [0027]    The components of tank  48  and its feed conduits, etc. may be made from any material which does not degrade when exposed to the liquids to be used therein. Preferably, a suitable plastic is used.  
         [0028]    Thus, the present invention provides an effluent discharging apparatus having separate reservoirs and which ensures that mixing of the liquids does not occur until the liquids enter the drain. This is advantageous in that the small diameter conduits and other parts of the apparatus do not clog with precipitate, reducing maintenance requirements significantly. Further, when a high velocity pump is used, clogging in the drain can be significantly reduced.  
         [0029]    The apparatus and method of the present invention can be used for discharging effluent from both colour and black and white photographic processes, as well as x-ray processes.  
         [0030]    As will be apparent to persons skilled in the art, various modifications and adaptations of the systems and methods described above are possible without departure from the scope of the appended claims.  
         [0031]    Apparatus  100  may optionally further include a floating plate (not shown) which floats on the top surface of fixer liquid  18 , occupying as much of the top surface as possible, to prevent contact of the fixer liquid  18  with air volume  20 , and therefore reduce the rate of production of precipitate.  
         [0032]    Utilizing reservoirs  17  and  43  to hold spent fixer and developer liquids  18  and  44 , allows the volumes of the two liquids to build up to a point where a small venturi can pump them without excessive use of carrier liquid. However, reservoirs  17  and  43  may be omitted and venturi  4  and  30  may be connected directly to sources of the two spent fixer and developer liquids, respectively. This configuration is less preferable, however, because it tends to result in higher consumption of carrier liquid per unit volume of liquid pumped.  
         [0033]    The present invention may also be used with advantage in discharging any liquids or fluids used in photographic processing, especially where preventing the mixing of at least two liquids is desired. Also, one skilled in the art will appreciate that more than two reservoir +venturi assemblies may be provided where more than two fluids are to be pumped.  
         [0034]    While a venturi is the preferred means of pumping, any other pumping means or evacuation means will work, such as a liquid pump. For example, referring to FIG. 2, the evacuator or evacuation means of the present invention may alternately comprise a pump  4 ′ and/or pump  30 ′. (It will be understood that all other elements of apparatus  100 ′ of FIG. 2 are substantially as described above, and therefore represented by the same reference numerals.) Alternately, a venturi may be used in association with one reservoir only (preferably the fixer liquid, as will be understood by one skilled in the art), while the other reservoir may be evacuated using another type evacuation means, such as a pump, or simply by gravity. Irrespective of the evacuation means employed, it is preferable to dilute the effluent, with a carrier liquid or otherwise, to further reduce the possibility of clogging within the system.  
         [0035]    A filter (not shown) may be provided to cover outlets  7  and/or  33 . Reservoirs  17  and  43  need not be in a single container, but may alternately be provided in separate containers. The manual and automatic purge features are desired but also not essential to the operation of the apparatus described.  
         [0036]    Still other modifications and adaptations of the apparatus and methods described above will be apparent to those skilled in the art but which do not depart from the scope of the appended claims.