AN APPARATUS FOR AND A PROCESS OF DETECTING POLLUTION IN AN AQUEOUS MEDIUM

Abstract: The invention concerns apparatus for detecting pollu­ tion of an aqueous effluent by soluble organic or inorganic compounds. The apparatus contains a sampler (19), an effluent reservoir (17), a clean water reservoir (11), a thermostatically controlled bath (15), a coalescer (1), a charcoal filter (2), a differential refractive index detector (3) and a U.V. detector (4). Effluent is intermittently sent through the apparatus from its reservoir (17) and at other times clean water of known purity is sent from its reservoir (11) through the apparatus. A comparison of the readings obtained in detectors (3) and (4) enables one to determine qualitatively the presence of soluble hydrocarbons and organic and inorganic soluble products in the aqueous effluent.

Description: DFTECTION OF POLLUTION This invention relates to appartus for detecting ollut; of an aqueous effluent ty soluble organic or inorganic coitipounds. There is a need for n apparatus or a device which enables one Continuously to take aqueous samples of sewage and to determine the extent of accidental pollution by pollutants. We have flow devised an apparatus for this purpose and which can be adapted to set off quickly an alarm so that adequate remedial action can be taken. According to this ir.vention, an apparatus fer detecting pollution of an aqueous effluent comprises: (a) a sampling device. (b) a reservoir for aqueous effluent, (c) a filter upstream of said reservoir (b), (d) a filter downstream of said reservoir (b), (e) a reservoir for water of known purity, (L) a filter downstream of said reservoir (e), (g) a thermostatically controlled bath connected by conduit to both reservoirs (b) and (e), (h) a coalescer downstream of said bath (g), (i) a device for absorbing hydrocarbons connected by conduit to coalescer (h). (j) either a differential refractive index detector connected by conduit to coalescer (h), or a conductimeter connected by conduit to bath (g) or by conduit to coalesce (h), (k) a U.V. detector downstream of said device (i) (1) means for conveying water of known purity from its reservoir (e) through filter (f), bath (g), coalescer (h), device (i), detector (k) and detector or conductimeter (j). and (m) means for conveying a sample of aqueous effluent frozen its reservoir (b) through filter (d) t bath (g), coalescer (h), device (i),detector (k) and detector or conductimeter (j). By comparing the readings obtained in the detector or conductimetr (j) and detector (k) > with on the one hand water of known purity and on the otlier hand effluent one is able to determine at least qdalitativcly the pollution in the effluent. Before the water of known purity thereinafDsr rtXerred to as ',:i water") and effluent are tested they must be collie lewd in reservol.st There are separate reservoirs for lean water and icr effluent. Th means of valves and a pump, the clean water and effTxlent can be separately conveyed to their respective reservoirs. The effluent and optionall)- clean water should also pass through filters before tbey pass to their reservoirs and also after they leave their reservoirs. A sample of the aqueous effluent is transferred to its reservoir (b) by means of the sampling device (a), and this conveniently is achieved by means of a suction/compression device to be described in more detail later. The clean water reservoir (e) may be provided with a level detector which operates the valve allowing clean water to enter its reservoir (e). Also the conduit through which the clean water passes on its wy to the reservoir (e) may be provided with a security device which stops the apparatus should clean water not be available The clean water which may be for example tap water, deionized water or distilled water supplies both its reservoir and the therncs- tatically controlled bath. After leaving its reservoir and after passing through its filter the clean water enters .4Sle thermostatically controlled bath and (g) the conductimeter (j) (when used) and then the coalescer (h). This bath controls the cemperature of the water going through the coalescer (h) and device (i). This bath may also be used, if needed for the thermostatic control of the conductimeter Ci) and of detector (k). Any overflow of clean water from the thermostatically controlled bath (g) can be returned back to the clean water reservoir. The means (1) for conveying clean water is usually a pump and by this means clean water is pumped from its reservcir through bath (g) to the conductimeter (j) (when used) and coalescer (h). A first part of the water leaving the coalescer (h) is removed frou the system, being sent to a sewer. A second part cf the water leaving the coalescer (h) is split between entering the device (i) through the conduit connecting the device (i) to the coalescer (h) and entering either the differential refractive index detector (i) (when used) through the conduit connecting it to the coalescer (j) or the U.V. detector (k) (when the differential refractive index detector is not used) through a conduit connecting it to the coalescer (h). Water emerging from the device (i) is conveyed either to the differential refractive index detector (j) (when used) or to the U.V. detector (k) (when the differential refractive index detector is not used). The coalescer (h) which coalesces droplets is usually a te iliet with resin. It can however be a tube filled with. glass or crg.nic fibres, polyurethane foam or other coalescing material. The device (i) for absorbing hydrocarbons is usually a charccal filter, and will hereinafter be referred to as the charcoal finite. The stream leaving the charcoal filter (i) is sent to the referent cells of the detector (j) (when used) and to the U.V. detector (k). It also enables one to detect on U.V. detector (k) saturation of the charcoal filter (i) because when products are not absorbed on the aharcnal filter a negative variation will appear on the reorder of the U.V. detector (k). The aqueous effluent whose pollution is to be detected is sampled for example from a sewer by the sampling device ldich is usually a suction/compression device. By this means it is possible to suck up the effluent into its reservoir (b) until a certain level is achieved. The sample is then allowed to decant in the reservoir (b). At various intervals, part of the aqueous effluent is passed from its reservoir (b). In a preferred embodiment it is passed through a pHmeter which acts as a first control of the aqueous effluent. If the pHvalue detected is outside a predetermined pH range, the value is recorded and the reservoir (b) is emptied under pressure by the suction/compression device and the pH-meter is cleaned by clean water. Then, the reservoir (b) is charged with new aqueous effluent sample. When the measured pH of the aqueous effluent is within the predetermined pH range, a measured part of the aqueous effluent is passed from its reservoir (b) through the above-described system instead of clean water. These intervals may for example be at 5 to 30 minutes. The amouDt of the sample and these intervals can be adjusted depending on the pollution level of the aqueous effluent. When the sample of the aqueous effluent has been removed from its reservoir (b), means are provided for automatically supplying clean water to the apparatus. Also during the analysis of the aqueous effluent, the aqueous effluent reservoir (b) is emptied under pressure by the suction/compression device and charged with new aqueous effluent sample. If a pH meter is used the meter is cleaned. When a conductimeter (j) is used, the measured part of the aqueou effluent passes through the thermostatically controlled bath (g) for temperature adjustment and then irto the conductirter (j) where the conductivity is measured and recorded giving info.nsation as to how much salt there is. The remainder of the aqueous effluent emerging from the coalescer (h) contains soluble products and is split into svo streams (as with tb clean water) a first stream entering the charcoal filter (i) and a second stream entering the W detector (k) or whel used, the differential refractive index detector (i). In the first alternative, i.e. when the second stream enters the U.V. detector, in said W detector (k), the second stream is compared with the first steam after it passed through the charcoal filter (i). Since the charucal filter (i) absorbs soluble h-ydrocarbons, this com- parison is made with clean water. The W detector (k) gives an analysis of the effluent, e.g. at 254 nm, it gives an indication of the presence of hydrocarbons (other than paraffins) and all oxygenated products. Similarly in the second aiternative when the second stream enters the differential refractive index detector (i), in said detector (j) the second stream is compared with the first stream after it has passed through the charcoal filter (i). Since the charcoal filter absorbs soluble hydrocarbons this comparison is made with clean water. The differential refractive index detector (j) gives a general idea of the pollution of the effluent whereas the U.V. detector can give an analysis of the effluent, e.g. at 254 nm it gives an indication of the presence of hydrocarbons (other than paraffins) and all oxygenated products. Since inorganic soluble products are not absurd on the charcoal, they pass through and are detected by the differential refractive in detector (j). A negative variation will appear on the recorder. Due to the difference in the passage time the two variation on the recorder are well indicated As an alternative to positioning the conductimeter (j) juanediately downstream of tlie bath (g) it may be positioned downstream of the coaiescer (h) provided it is upstream of the split of the exit line from the coalescer (h) i.e. before the line divides into entering the charcoal filter (i) and the U.V. detector (k). All the information obtained from the pll-meter, the coiducti'iere and U.V. detector can be recorded and the apparatus can be monito-ied by installing limits and alarms e.g. lamps, bells etc., which inform people about the variation of the composition of the stream or maintenance problems. A particular form of apparatus according to the invention is now described with reference to Fig. 1 of the accompanying drawing. Clean water enters its reservoir 11 via an electro valve V8 and a security device Sl. This reservoir is provided with a level detector 12. Overflow water passes through conduit 13 to the sewer pipe 14. Clean water is sucked up through filter F1, electro valve V7 by means of pump P and enters a coil 22 in the thermostatically controlled bath 15. From this coil 22 clean water is conveyed to coalescer 1. Water leaves the coalesce l by line B, and enters both the charcoal filter 2 and the differential refractive index detector 3 and then the U.7. detector 4. Water emerging from charcoal filter 2 also passes to detector by line C. Another stream A leaves the coalescer 1 and is sent to the sewer 16. Clean water also enters bath 15 by means of line 21 and returns to the reservoir 11 by means of line 20. heat exchange o.urs between this water and that passing througn coil 22. If the telsserature of tbe detectors has to be controlled, the thermostatically controlled bath I supplies warm water for example, through dotted line 24 and returns through dotted line 25. Aqueous effluent is drawn up to its reservoir 17 through a filtc;- F2 and electro valve V1. The reservoir 17 has a leT21 detector 18 aid a security device S2 and is connected to a suctionico-pression device 15 having electro valves V2, V3, V4 and V5. After leaving the reservoir 17 via filter F3, electro valve V6 and pump P the aqueous effluent passes through the coil 22 in the thermosstatically controlled bath 15 and onto the coaleseer 1, charcoal filter 2 and detectors 3 and 4 and to sewer 16 in the sans way as described in connection with the clean water. Clean water is continuously drawn up to its reservoir 11 and to the thermostatically controlled bath 15. When the required level in reservoir 11 is reached, the level detector shuts off the electro valve V8. The security device S1 stops the apparatus-snould there be no clean water available to be drawn into the reservoir 11. Clean water is then drawn up by means of pump P through filter F1, arid electro valve V7 and through the coil 22 in the bath 15 to the coalescer 1, charcoal filter 2 detectors 3 and 4 and sewer 16 as previously described. Overflow from bath 15 returns te reservoir 11 by means of line 20. From time to time, aqueous effluent is sent t'nrough the apparatus instead of clean water. This is achieved as follows: The suction/compression device 19 comprises a mall air compressor with four electrovalves V2, V3, V4 and V5. When V2 and V4 are open and V3 and V5 closed, suction is applied to the reservoir 17. When V2 and V4 are closed and V3 and V5 are open, compression is applied to the reservoir 17. The reservoir 17 is provided with a security device S2 which prevents high vacuum or high pressure. When valves V2 and V4 are open and suction occurs in the reservoir 17 and when the water level reaches the level of the level detector 18 the compressor stops and the electro valves V1, V2 and V4 are closed. There is then 2 decantation phase in the reservoir 16. When programraed a sample of aqueous effluent is removed from the reservoir 17, electro valve V7 having been sWlUclìeu riff aid electro valve V6 switched on. When this sample has been removed from the reservoir 17, the electro valve V6 is closed and electro valves Xt1, V3, V5 and V7 are opened. This enables the reservoir 17 to be emptied and for the filter F2 to be cleaned and clean water san through the apparatus once more. The sample of aqueous effluent obtained from then reservoir 17 then enters the thermostatically controlled bath 15 and then to the coalesce 1 where insoluble hydrocarbons are separated. These insoluble products are sent back to the sewer 16 by stream A. Streara r > emerging from the coalescer 1 contains soluble products and is split between the detectors 3 and 4 and the charcoal filter 2. In the diffetential refractive index detector 3, the stream B is compared with the clean water C emerging from the ctla.coal filter 2. From this comparison one is able to obtain a qualitative idea of the total pollution of the effluent and of the inorganic soluble products. The U.V. detector 4 enables one to determine the presence of iiydro- carbons other than paraffins and all oxygenated compounds. Fig. 2 shows typical readings obtained on the chart recorder from the differential refractive index detector (j) and from the U.V. detector (k). Fig 3 shows the typical sequence of liquid parsing through the differential refractive index detector (j) and the U.V. detector (k). Thus, it can be seen how these detectors can detect the presence of soluble hydrocarbons and organic and inorganic soluble products. It is worth re-iterating that in the coalescer all insoluble organic products are removed and can be sent to the sewer, e.g. via line A. Effluent containing salts plus soluble hydrocarbons is sent to detectors (j) and (k) where there are comparisons with clean water. In the next step in the cycle the nature of the liquids entering the detectors (j) and (k) are reversed and the presence of soluble salt in the effluent can be detected. In the final step of the cycle, clean water enters the detectors (j) and (k) and this forms the base line for the detectors. Another form of apparatus according to th 1-nvctIon is now now describe with reference to Fig. 4 of the accompanying drawings Clean water enters its reservoir 7 via a security device 5° filter F3 and an electrovalve 12. This reservoir is provided with a level detector 10 . Electrovalves V8 and V10 having been switched off, clean water is sucked through filter F4, electrovalve V9 by means of pump P and enters a coil 11 in the ther.nostatical y-controlled barh 5 . From this coil 11 , clean water is conveyed through a conductirte± 4 and then to a coalescer 1 . Water leaves the coalescer 1 by line B. The line is split into two parts, the first goirg to the U.V. detector and the second (line C) going through the charcoal filter 2 and the LiV detector 3 . Water emerging from the charcoal filter 2 also ass to detector 3 by line C. Another stream A leaves the coslescer 1 and is sent to the sewer 12 . Clean water also enters bath 5 by means of line 13 and overflow returns to reservoir 7 by means of line 14 . Heat exchange occurs between the water in the bath and that passing through coil 11 Aqueous effluent is drawn up to its reservoir 8 through a filter F and electrovalve V . The reservoir 8 has a level detector 15 and 1 6 a security device S2 and is connected to a suctionleempression device 9 having electrovalves V1, V2, V3 and V4 and an air compressor C. The sampled aqueous effluent water can be stripped in the reservoir 8 and the gas sent out through the electrovalve V5. After leaving by gravity the reservoir 8 via filter F2, the aqueous effluent passes through an electrovalve V7 and a pHieter 6 and is sent to the sewer 12 . When the measured pH is inside the predetermined pH range, the aqueous effluent, after leaving the reservoir 8 via filter F2,electrovalve Pump P and electrovalve V11, passes through the coil 11 in the thermostatically-rontrolled bath 5 and onto the conductlmeter 4 > coalescer 1 , charcoal filter 2 and detector 3 , and to sewer 12 , in the same way as described in connection with the clean water. Line D and electrovalve V10 are used for cleaning the pH-meter 6 Clean water is continuously drawn up to its reservoir 7 and to the thermostatically-controlled bath 5 . When the required level in reservoir 7 is reached, the level detector shuts off the electrovalve V12. The security device S1 stops the apparatus should there be no clean water available to be drawn into the reservoir 7 . Clean water is then drawn up by means of pump P through filter F4 and electrovaR e V9 and through the coil 11 in the bath 5 to the coductimer 4 the coalescer 1 , the charcoal filter 2 : the detector 3 and the sever 12 Åas previously described. Overflow from bath 5 returns to reservoir 7 by means of line 14 From time to time, aqueous effluent is sent through the apparatus instead of clean water. This is achieved as follows: the suction!com pression device 9 comprises a small air compressor with four electrovalves V1, V2, V3, V4. When V1 and V2 are open and V3, V5 and V13 are closed, suction is applied to the reservoir 8 . When V1, V2 V5, a are closed and V3, V, are open, compression is applied to reservoir 8 4 The reservoir 8 is provided with a security device which prevents high vacuum or high pressure. When valves V1, V2 and V6 are open and V3 V4, V5 and V13 are closed, suction occurs in the reservoir 8 , effluent is drawn into the reservoir and when the water level reaches the level of the level detector 15 the compressor stops and the electrovalves V6, V1 and V2 are closed. There is then a stripping phase in the reservoir 8 , the electrovalves V3, V4 and V5 are open and the compressor running. When programmed, a sample of aqueous effluent is removed by gravity from the reservoir 8 , electrovalves V7 and V13 having been switched on, the aqueous effluent passes through the pH-'meter 6 and is sent to the sewer 12 As previously described, depending on the pH value, the electro valves V7 and Vg are switched off and electrovalwe Te is switched on and then a sample of aqueous effluent is removed by means of the pump from the reservoir for conductivity and IN determinations. When the sample has been removed from the reservoir ss , the elect-:o- valves V1, V8 and V13 are switched off and electrovalves V1, V2, V6 and Vg are switched on and the compressor run. This enables the reservoir 8 to be emptied under pressure and for the filter all to be cleaned arid clean water sent through the apparatus once more. Then the compressor is stopped and electrovalves V11 and V13 are switched off and electrovalves V7 and V10 are switched on, this allows the cleaning of the pH meter 6 . After cleansing tile pH-meter, the electrovalve V10 is switched off and the electrovalvo 11 is switched on and clean water sent through the apparatus. The sample of aqueous effluent obtained from the reservoir 8 then enters the thermostatically-controlled bath 5 and then the conductimeter where the conductivity is measured and then the coalescer 1 wherc the insoluble hydrocarbons are separated. These insoluble products are sect back to the sewer 12 by stream A. Stream B emerging from the coalescer 1 contains soluble products and is split between the W detector 3 and the charcoal filter 2 The UV detector 3 enables one to determine the presence of soluble hydrocarbons. Fig. 5 shows typical reading obtained on the chart from the p- meter, conductimeter, and from the W detector. The apparatus of this invention can be used in for example refineries, chemical plants, storage plants, and any industrial plants where it is desired to detect pollution in aqueous effluent.

Claims: ClAIMS 1. An apparatus foi detecting pollution o. ar. at; outs effluent z!hicll comprises: (a) a sampling device. (b) a reservoir for aqueous effluent, (c) a filter upstream of said reservoir (b), (d) a filter downstream of raid reservoir (b) (e) a reservoir for clean water (as hereiube-iore defined), (f) a filter downstream of said reservoir (c), (g) a thermostatically controlled bath corected by conduit to both reservoirs (b) and (e), (h) a coalescer downstream of said bath (g), (i) a charcoal filter (as hereinbefore defined) connected by conduit to (h) (j) either a differential refractive index detector connected by conduit to coalescer (h), or a conductimeter connected by conduit to both (g) or by conduit to coalescer (h), (k) a U.V. detector downstream of charcoal filter (i) (1) means for conveying clean water from its reservoir (e) through filter (f), bath (g), coalescer (k), charcoal filter (i), detector (k) and detector or conductimeter (j), and (m) means for conveying a sample of a aqueous effluent from its reservoir (b) through filter (d), bath (g), coalescer (h), charcoal filter (i), detector (k) and detector or coriductimeter (i). 2. An apparatus according to claim 1 wherein the sampling device (a) comprises a suction/compression device. 3. An apparatus according to either of claims 1 and 2 wherein the clean water reservoir (e) is provided with a level detector. 4. An apparatus according to any one of the preceding claims wherein the means (1) for conveying clean water is a pump. 5. An apparatus according to any one of the preceding claims which includes means for automatically supplying clean water to the apparatus when aqueous effluent has been removed from its reservoir. 6. An apparatus according to any one of the preceding claims wherein a conductimeter is used and there is a pH meter connected to the reservoir (b). 7. An apparatus according to any one of the precng claims Ut.' includes a filter located llpstream of reservoir (e). 8. An apparatus according to claim 1 substantially as hereinbefore described with reference to Fig. 1, 2 and 3 the drawiiigs. 9. An apparatus according to claim 6 substantially as hereinbefore described with reference to Fig 4 ad 5 of the drawings. 10. A process of detecting pollution in an aqueous effluent which comprises passing intermittently said effluent through the apparatus according to any one of claims 1 to 5 and 8 and at other times conveying continuously clean water through said apparatus ano comparing readings obtained from the differential refractive index director (j) and from the U.V detector (k). 11. A process according to claim lO herein a first part of water leaving coalescer (h) is removed from the system and the second part of water leaving coalescer (h) is split between entering charcoal filter (i) and entering the differential refractive index detector (j). Ct 12. A process of detecting pollution of an aqueous effluent which comer sews passing intermittently said effluent through the apparatus according to either of claims 6 and 9 and at other times conveying continuously clean water through said apparatus and comparing readings obtained from the pH-meter, the conductimeter (j) and the W detector (h). 13. A process according to claim 12 wherein a first part of the water leaving the coalescer (h) is removed from the system and the second part of water leaving the coalescer (h) is split between entering charcoal filter (i) and entering the W detector (h).

Inventors: AKOUN, GERALD LAZARE, MULLER, JEAN-MARIE
Applicants: ESSO SOCIETE ANONYME FRANCAISE
Application year: 1979
Main classification: G01N33
IPC codes: G01N33