FR2770838A1 - Effluent treatment system for photographic solutions - Google Patents

Abstract

The series-connected circuit commences with the inlet feed pump (18) and filtration module (10). It continues with the transfer line and pump (46, 48) to the concentration module (12). This module has a line and pump (106, 108) recycling to the filtration module. The main flow continues through a transfer line and pump (86,88). The system is completed by a discharge module and line (14, 118). Preferred features: The first module includes filtration column(s) (20, 40) with level detector and progressively increasing retention capability. The concentration tank (52) takes the filtrate and is heated (58) for evaporation. The vapor leaving (66) is condensed (76) and recovered (74). The concentrate tank (100) has a filter (104) and return line (106) to the last filtration column. The concentrate filter has a retention efficiency approaching that of the filtration column. Vapors not condensed, are recirculated through a cooler (90), filter and blower to the evaporation tank. There is active carbon filtration in the discharge module and a level detector. The level detector is a float and tube arrangement. A computer controls all operations.

Description

DEVICE FOR TREATING CHARGED LIQUID, ESPECIALLY
PHOTO BATHROOM EFFLUENTS
The present invention relates to a device for separating and concentrating charged liquids, in particular effluents from photographic baths so as to be able to discharge water directly into the public wastewater network, according to the standards in force and to be able to recover sludge collected for specific processing.

 We know that many industries produce charged effluents whose content of polluting or dangerous elements for the environment does not allow a discharge directly into the public sewage network. On the contrary, these effluents must be treated specifically by specialized companies which invoice the service, quite logically, in proportion to the volumes of effluents.

 Certain entities with sufficient effluent volumes may consider treating their own effluents with a view to concentrating them and discharging the separated water directly into the wastewater network and collecting the concentrated sludge for separate treatment in specialized entities .

 The financial statement, taking into account the depreciation of the installation, can be profitable provided that the installation is of a low cost price and that the reliability is very high, because the margins are very narrow.

 One can imagine large-scale settling facilities with natural evaporation, but such a project comes up against problems of surface availability. For a photographic laboratory located in the city, such a project cannot be envisaged, including for odor problems.

 In addition, the treatment of effluents must also be reliable because the photographic laboratories often work continuously, 7 days 7 days. It is also necessary to be able to adapt the capacities according to the needs but in all cases, the processing capacity must be sufficient so that the operator only intervenes periodically on the installation and does not have to worry about it every day. .

 The present invention aims to propose a processing device which meets these specifications. This device uses simple elements excluding any internal integrated electronics, so as to reinforce reliability because the electronic elements near or in contact with liquids are subjected to an aggressive atmosphere which can be a regular cause of breakdowns and failures.

 The compactness of the device is an important advantage of the device which addresses the problem of the small areas available for such installations.

 The device is entirely in closed circuit, which eliminates any odor problem.

To this end, the device according to the invention, for the treatment of loaded liquid effluents like effluents from photographic baths, is characterized in that it comprises a circuit in series with at least the succession of the following elements
- a supply of charged liquid effluents, with a pump
feed,
- a mechanical filtration module, with a transfer pump,
- a concentration module, with a transfer pump and a
recycling pump,
- a rejection module, and
- a discharge line for purified waste water.

 This filtration module comprises at least one mechanical filtration column with a level detector and more particularly this module comprises two columns in series with increasing retention capacity.

 According to a particular embodiment, the concentration module comprises at least one concentration tank provided for receiving the filtrate from the mechanical filtration module, this tank comprising heating means for producing steam and means for discharging the concentrate, means for evacuating said vapors, means for condensing said vapors, a tank for collecting condensed liquids.

 In this concentration module, the means for evacuating the concentrate comprise a recovery tank equipped with a mechanical filter and a recycling pipe provided with a pump and opening upstream of the last column of the filtration module and the mechanical filter has a retention capacity less than or equal to that of the downstream column of the mechanical filtration module.

 According to another characteristic, the concentration module comprises a circuit for recirculating non-condensed vapors, said circuit comprising a recirculation passage connecting a first zone located immediately above the recovery tank for condensed liquids and downstream of the condensation means to an area forming the sky of the concentration tank, a recirculation turbine, a mechanical filter interposed on the recirculation path.

 The rejection module comprises at least one activated carbon filter.

 According to a preferred embodiment and particularly applicable to the present invention, the liquid level detection means comprise a vertical tube associated with the container in which said liquid is disposed with a communication between this container and this tube, a central guide coaxial with said tube in which are arranged switches with flexible blades regularly spaced over the entire height and a float, free in the vertical tube, mounted coaxially and sliding around the guide with a magnet embedded tightly in the material of the float.

 The present invention also provides a programmable controller equipped with connections to all the active elements such as pumps, level detection means, heating means, the turbine.

The device according to the invention is described below according to a particular non-limiting embodiment, with reference to the appended drawings in which the different figures represent:
- Figure 1, a general schematic view of the device with its
fluid circulation, and
- Figure 2, a detailed view of the level control means of
different volume containers such as bins, columns.

For the rest of the description and for the invention, it is meant
general the term "filter" as being able to also group the family of
decanters.

 FIG. 1 shows the device essentially comprising a filtration module 10, a concentration module 12 and a rejection module 14.

 The filtration module 10 is supplied by a pipe 1 6 coming from the film and photographic paper processing tanks in the case of a photographic laboratory, example retained for the present description.

 This pipe comprises a feed pump 1 8 and opens into a first static filtration column 20 of the cartridge column type 22 schematically represented by a filter element. The retention capacity is fixed at dimensions greater than 100 lim.

 This column is equipped with level detection means 24.

 These means 24 are described generally, with reference to FIG. 2, because these means will be repeated in the following description and they have in themselves special characteristics.

 In Figure 2, there is shown a level detector 25, as referenced 24 in the embodiment described, in the form of a vertical tube 26, mounted parallel to one of the walls and over the entire height of the container which one wishes to measure the level of liquid contained.

 This vertical tube 26 includes a vent 28 at the top and a connection 30 at the bottom with the interior volume of the container so that the liquid, by the principle of communicating vessels, is at the same height in the container and in the tube 26 .

 A float 31 is slidably mounted around a hollow central guide 32.

This float 31 comprises a magnet 34 placed in line with the water line of said float, embedded in a resin so that it is perfectly isolated from the liquid medium.

 In the hollow central guide, switches 36 with flexible blades are staged regularly over the entire height of this guide, more exactly over the entire effective height of the liquid to be measured.

 Thus the float 31, by moving, causes, by its magnet 34, the closing of the corresponding flexible blade switch, giving the indication of the level, this without contact of the sensitive elements with the liquid.

 A connecting pipe 38 connects the outlet of the first filtration column 20 to the second filtration column 40. This second column is identical to the previous one, but it is equipped with a filter 42, the retention capacity of which is fixed at dimensions greater than 10 μm.

 A pump 44 transfers the first column 20 to the second column 40.

 A pipe 46, fitted with a pump 48 connects the filtration module 10 to the concentration module 12.

 This concentration module 1 2 comprises a closed enclosure 50, in the upper part of which is arranged a concentration tank 52 in the upper part of which opens the pipe 46 for connecting the filtration module to the concentration module.

 This tank 52 has an inclined bottom in frustoconical shape to ensure the accumulation of decanted elements in the lower central part of said tank.

This lower central part is provided with an outlet 54, equipped with a plug closure system 56.

 In this tank, there is provided a set of resistors 58 which are arranged in the lower part of said tank so as to be able to heat the liquid contained to produce steam.

 Above the tank 52, a cover 60 is provided with outlets 62 with vents. These vents have a shape and an inclination adapted to prevent the condensate from falling back into the tank 52 and to promote its supply to its final destination.

 The cover 60 forms with the upper wall 64 of the enclosure a discharge passage 66.

 Means 68 for level detection similar to the detector 25 described above, are associated with the tank 52.

 A probe 70, placed in the tank, controls the temperature.

 A recirculation pump 72 is arranged in the lower part of the tank to allow a certain mechanical homogenization complementary to the natural convection as will be shown later in the description.

 The discharge passage 66 extends vertically to open into a container 74 for collecting the condensation water, in the lower part of the enclosure 50.

 On the path, there are disposed condensing means 76 which comprise, in known manner, walls 78 cooled by a circulation of heat transfer fluid coming from a cold source, not shown.

 The recovery tank 74 comprises baffles 80 interposed on the path of the liquid accumulated in said tank. This tank is equipped with a recirculation pump 82 allowing homogenization of the liquid. This tank also includes level detection means 84, similar to the level detector 25.

 This tank is connected by a pipe 86 to the rejection module 14 with a circulation pump 88.

 There is also provided inside the enclosure of the concentration module, a recirculation of hot air. The circuit necessary for this recirculation comprises a recirculation passage 90 which is stitched on the discharge passage 66, at its lower end, after the condenser.

 The recirculation corridor is equipped with baffles 92 and includes a mechanical filter 94, of the fibrous type, then a turbine 96 for ventilation which ensures the circulation of air. The recirculation corridor is advantageously delimited by the walls of the concentration tank 52, by the corresponding walls of the enclosure 50 and by a part 98 of the cover 60 which makes it possible to channel the air towards the free volume above the liquid contained. in the concentration tank 52.

 The concentration module finally includes a recovery part for concentrated materials more generally called sludge. This part essentially consists of a recovery tank 100 with level detection means 102, similar to the level detector 25, this tank having a capacity at least equal to that of the tank 52.

 A mechanical filter 104 provides prefiltration of the sludge from the concentration tank 52, to 100 lim, in the same way as the filter of the first column 20.

 The filtrate is discharged through a return line 106, equipped with a transfer pump 108, said line opening into the second filtration column 40 to 10 μm, for recycling of the liquid.

 The rejection module 14 is supplied by the output line 86 of the concentration module 1 2. This module comprises, in the upper part, a filter 110 with activated carbon, a passage 1 1 2 with baffles as well as means 114 for level detection, of the same type as the aforementioned level detector 25 and described.

 A recirculation pump 116 ensures homogenization.

 The rejection module 14 is directly connected to the wastewater evacuation network by an outlet pipe 1 1 8.

 All the active and measuring components of the device, namely the pumps, the level detection means, the temperature probe, are connected to a control module 1 20 in the form of a programmable controller which governs the different phases. of operation as is now described.

 The device is supplied with effluents through the supply line 16. These effluents are filtered at 100 μm in the first column 20 then the filtrate is transferred to the second column 40 where it is filtered at 101 μm.

 Thus, particles above 10 lim are retained in the cartridges of the two filtration columns, for the most part.

 The different phases of filling the columns and switching from one to the other are carried out by the programmable controller 120 in which the levels have been recorded, which allows the pumps to be started once the programmed levels have been reached, the signal being given by the level detection means 24.

 The filtrate is led into the concentration tank 52 where it accumulates until the level detection means 68 inform the automaton that the maximum level of the tank is reached.

 Consequently, the resistors 58 are supplied to heat the liquid contained in the concentration tank, which ensures the vaporization of the water contained, vaporization which is facilitated by the circulation of the gaseous atmosphere above the liquid generated by the turbine 96.

 The vaporized water is led to the condenser, which causes it to return to the liquid state and its accumulation in the accumulation tank 74.

 The non-condensed vapor is brought back to the gaseous sky of the concentration tank, through the mechanical filter 94.

 Once the maximum level has been reached in the accumulation tank 74, the detection means 84 inform the programmable controller which starts the pump 88, ensuring the transfer of the condensed water to the discharge module 14.

 This water is then treated with activated carbon, which has the effect of neutralizing odors before being discharged into the wastewater evacuation network.

When the liquid level in the concentration tank 52 is insufficient, that is to say immediately above the resistors 58,
The programmable controller stops the heating by the resistors 58, the turbine 96, the condenser 76 with the necessary time delays.

The device then waits for a new filling of liquid to be treated,
The whole being put on standby except the stirring pump 72 which avoids the settling of sludge at the bottom of the tank 52.

 The cap 56 is opened and the highly charged and highly concentrated liquid is discharged from the concentration tank 52, through the hole 54, to the recovery tank 100.

 The highly concentrated liquid is again filtered in this tank by the mechanical filter 104 at 100 lim, which makes it possible to retain any particles of large diameter which may have passed through the concentration tank 52.

 The retentate on the filter is intended to be evacuated and treated like the retentates of the cartridges of the first and second columns, by a specialized unit.

 As for the filtrate, it is recycled by a transfer upstream of the second column in order to mechanically treat this filtrate at 10 clam. The liquid is then treated again as before.

 Maintenance of the device comes down to removing saturated cartridges and replacing them with new cartridges.

 It may be noted that the installation is intended to operate discontinuously in the case of the preferred embodiment, which can allow the programming of the concentration treatment during the periods at reduced electricity tariff since it is the only energy consumption and the only running cost with the price of cleaning and changing filters.

 To give orders of magnitude, such a device is entirely satisfactory for a photographic laboratory processing up to 50,000 m2 of paper per year. This activity generates around 100 liters of charged liquid per day.

 One can also benefit from a heat source of the solar collector type since the treatment is generally programmed at night, the hot water having been accumulated throughout the day.

 It will of course be noted that the various tanks and more generally all the parts in contact with the liquid or the vapors are made of stainless steel, the pumps are of the magnetic drive type and the rolling axes are of polytetrafluoroethylene.

 Conveniently, the pipes are made of flexible polytetrafluoroethylene with a metal braid of external reinforcement, the ends being fitted with waterproof quick connectors when disconnected, so that the columns can be easily disconnected, for example.

 It should also be noted that all of the circuits have been described in a fluid and schematic manner without going into practical practical details within the reach of those skilled in the art. This is why many pipes must be fitted with non-return valves such as the supply or recirculation pipes.

 Likewise, provision can be made for cleaning the tank of the working tank 52 with jets of pressurized clear water if necessary.

 The inlet filter module can also be replaced by a settling module depending on the products to be treated. In this case, baffles ensure the removal of the heaviest particles, which also ensures effective pretreatment.

Claims (9)

 1. Device for treating liquid effluents loaded as effluents from photographic baths, characterized in that it comprises a circuit in series with at least the succession of the following elements  - a supply (16) of charged liquid effluents, with a pump  <1 8) feed,  - a mechanical filtration module (10), with a pipe (46) and  a transfer pump (48),  - a concentration module (12), with a pipe (86) and a  transfer pump (88) and a pipe (106) and a pump (108)  recycling,  - a rejection module (14), and  - a pipe (118) for discharging purified waste water.  2. Treatment device according to claim 1, characterized in that the filtration module (10) comprises at least one column (20,40) of mechanical filtration with a level detector (24).  3. Treatment device according to claim 2, characterized in that the filtration module (10) comprises two columns (20,40) in series with increasing retention capacity.  4. Treatment device according to claim 1,2 or 3, characterized in that the concentration module (12) comprises at least one concentration tank (52) provided for receiving the filtrate from the mechanical filtration module, this tank comprising heating means (58) for producing steam and means (100) for evacuating the concentrate, means (66) for evacuating said vapors, means (76) for condensing said vapors, a tank (74) for recovery of condensed liquids.  5. Treatment device according to claim 4, characterized in that the means for evacuating the concentrate comprise a recovery tank (100) equipped with a mechanical filter (104) and a recycling pipe (106) provided with a pump (108) and opening upstream of the last column (40) of the filtration module.  6. Treatment device according to claim 5, characterized in that the mechanical filter (104) has a retention capacity less than or equal to that of the column (40) downstream of the mechanical filtration module.  7. Treatment device according to one of claims 4 to 6, characterized in that the concentration module comprises a circuit for recirculating uncondensed vapors, said circuit comprising a recirculation passage (90) connecting a first zone located immediately at the above the tank (74) for recovering condensed liquids and downstream of the means (76) of condensation to an area forming the sky of the concentration tank (52), a recirculation turbine (96), a mechanical filter (94) interposed on the recirculation path.  8. Treatment device according to any one of the preceding claims, characterized in that the rejection module (14) comprises at least one filter (110) with activated carbon and means (114) for level detection.  9. Treatment device according to any one of the preceding claims, characterized in that the liquid level detection means (25) comprise a vertical tube (26) associated with the container in which said liquid is placed with a communication (30 ) between this container and this tube, a central guide (32) coaxial to said tube in which are arranged switches (36) with flexible blades regularly spaced over the entire height and a float (31), free in the vertical tube, mounted coaxial and sliding around the guide with a magnet (34) sealed in the material of the float.  1 0. Device according to any one of the preceding claims, characterized in that it comprises a programmable automaton (120) equipped with connections with all the active elements such as the pumps, the level detection means, the heating means. , the turbine.