Abstract:
The invention relates to a device ( 10 ) for capturing odor- and/or taste-generating substances present in water flowing continuously in a water distribution network via a pipe ( 12 ). In characteristic manner, the device comprises:
       capture means ( 22 ) for capturing said substances;   at least one chamber ( 18 ) containing said capture means ( 22 ) and suitable for having network water flow therethrough; and   hydraulic link and connection means ( 14; 42 ) between said chamber ( 18 ) and said pipe ( 12 ).       
 
     The invention is applicable to networks for distributing drinking water.

Description:
FIELD OF THE INVENTION 
     The invention relates to water distribution networks, and in particular to networks for distributing drinking water. More precisely, the invention relates to a device and a method for capturing odor- and/or taste-generating substances present in the water flowing in a pipe of a water distribution network. 
     BACKGROUND 
     The term “capture” is used to mean trapping or extracting odor- and/or taste-generating substances in order to characterize them, as opposed to systematically eliminating them. 
     In this field, there is a legal requirement to monitor water quality, either periodically or as a function of needs, and very particularly to monitor drinking water distributed by a network. 
     Such inspections can be triggered in particular when a possibly characteristic taste and/or odor is detected by a customer or a user of the distribution network. 
     At present, when a bad taste and/or a bad odor is detected in water, the procedure is as follows:
         the person concerned calls the complaints center associated with the water distribution network;   a member of the water distribution network staff goes to the premises where the detection occurred in order to bottle a sample of water;   the sample is then sent to an analysis laboratory;   substances generating the taste and/or odors in question are then extracted; and   the extracted substances are analyzed.       

     Concerning the above steps, it is considered that extraction requires a duration of about two hours while an analysis can be performed within the following 24 hours. 
     Nevertheless, it is known for taste- and/or odor-generating substances to appear in water intermittently over time and that the odor (or taste) thresholds of the compounds in question are extremely low compared with the sensitivity of commonly-used detection equipment. 
     Consequently, the above-described procedure very rapidly reaches its limits in terms of effectiveness. 
     In other words, that prior art procedure raises the problem of conserving the entire “matrix” responsible for the taste and the odor of the water, between the time a sample is taken and the time extraction is performed in the laboratory, and the time lapse between the taster detecting the taste and the time a sample is taken is also often too long. 
     Nevertheless, that is a procedure that is normally used for characterizing the origin of the odor or the taste of certain waters. 
     SUMMARY 
     An object of the present invention is to provide a device and a method enabling the drawbacks of the prior art to be overcome, and in particular making it possible to extract the compounds that might correspond to taste- and/or odor-generating substances directly from the water network. 
     In particular, it is desired to provide a device and a method that make it possible, at least at the selected moment, and continuously, to extract the intermittently-present molecules that might correspond to the taste- and/or odor-generating substances, which device and method present simplicity and speed of implementation, and also greater sensitivity, by accumulating odor molecules from the sample over time. 
     To this end, according to the present invention, the device for capturing odor- and/or taste-generating substances present in water flowing continuously in a water distribution network via a pipe is characterized in that it comprises:
         capture means for capturing said substances, said capture means being of the type acting by sorption;   at least one chamber containing said capture means and suitable for having network water flow therethrough; and   hydraulic link and connection means between said chamber and said pipe.       

     In this way, it can be understood that by positioning the device it is possible to capture on a continuous basis from the network any odor- and/or taste-generating substances present in the water at any moment, and in particular regularly for the purpose of monitoring water quality without involving personnel in the extraction step, thereby limiting the corresponding costs. 
     This solution also presents the additional advantage of making it possible not only to extract water easily in situ, but also to do so over a long period, thereby enabling molecules that are responsible for the taste and/or odor of the water to be captured even when they appear intermittently. 
     For example, the chamber providing contact between the water and the capture means is formed by a tube that is open at both ends. 
     Overall, the solution of the present invention makes it possible significantly to improve performance in searching for odorous compounds in order to identify the looked-for substances, and consequently to take early action seeking to improve water quality. 
     Said capture means of the type acting by sorption preferably comprise at least one support receiving at least one capture element comprising a layer of polydimethylsiloxane (PDMS) (where PDMS is capable of directly covering the support or else can be situated on the surface of the capture element that is itself mounted on the support). 
     Likewise preferably, said support includes a magnetic portion, the magnetic portion being covered by a polymer of the polydimethylsiloxane (PDMS) type. For example, the magnetic portion may be a glass bar covered in a polymer of the polydimethylsiloxane (PDMS) type, and having a magnetic bar encapsulated therein. 
     Capture means of this type are described in patents EP 1 039 288, EP 1 406 077, and EP 1 610 124 in the name of the company Gerstel Systemtechnik GmbH &amp; Co., KG. 
     According to the invention, in order to avoid making subsequent measurements erroneous as a result of the materials used in the device and that come into contact with the water, provision is advantageously made for the materials constituting the device not to give off compounds that might impede the capture of odorous molecules. For example, use is made of polytetrafluoroethylene (PTFE) or Teflon (registered trademark), of stainless steel, and/or of glass. 
     Furthermore, in a preferred embodiment, said hydraulic link and connection means comprise a quick-coupling system for coupling to an outlet faucet on user premises. 
     In another preferred embodiment, said hydraulic link and connection means comprise tapping means (i.e. means for making a wet connection) between the pipe and said chamber, together with means for discharging water from said chamber. Thus, a water connection is made without interrupting the flow along the distribution pipe for a city or a building. By way of example, the tapping comprises a coupling constituted essentially by a pipe saddle and a stop cock. 
     Provision can also be made for said tapping means to include a stop cock or valve. 
     Advantageously, it is also possible to provide for said tapping means to include a releasable fastener system enabling the chamber to be replaced easily. 
     In another advantageous disposition, said hydraulic link and connection means includes a flowmeter. Where appropriate, the flowmeter makes it possible to control the flow rate of water through the contact chamber. 
     In a variant embodiment, the device further includes a system enabling a liquid solution acting as a standard to be injected into said chamber together with the water flowing therethrough. The liquid solution is a solution containing one or more identified standard molecules suitable for being absorbed by the sorption support, and enabling trapped compounds to be quantified. 
     The present invention also provides a method of capturing odor- and/or taste-generating substances present in water flowing continuously in a water distribution network via a pipe. 
     To this end, the invention provides for the capture method to be implemented by passing network water through a chamber containing capture means for capturing said substances and connected to the pipe via hydraulic link and connection means. 
     One or more of the following dispositions is/are preferably adopted:
         the flow of water through the chamber is also measured and/or adjusted; and   a liquid solution acting as a standard is also injected into said chamber at the same time as water flows therethrough.       

     In the context of the present invention, the method described is implemented and the device described is used in particular for a drinking water network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages and characteristics of the invention appear on reading the following description made by way of example and with reference to the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic overall perspective view of the device of the invention; 
         FIG. 2  shows in greater detail the chamber and the means for capturing odor- and/or taste-generating substances present in water; 
         FIG. 3  is a profile view of the capture means contained in the chamber shown in  FIG. 2 ; 
         FIG. 4  is a diagrammatic overall perspective view of a variant of the device of the invention; 
         FIGS. 5 to 7  show another variant embodiment of the device in accordance with the invention; and 
         FIGS. 8 and 9  show two other solutions for making the variant in accordance with  FIGS. 5 to 7 . 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1 , there can be seen a device  10  in accordance with the present invention that is mounted on a mains pipe  12 , e.g. forming part of a drinking water distribution network. To this end, tapping means  14  is mounted on the pipe  12  and is connected via a first hose  16  to the inlet of a chamber  18  whose outlet is connected to a second hose for delivering water. 
     The tapping means  14  and the first hose  16  form hydraulic linking and connection means between the chamber  18  and the mains pipe  12 . It should be observed that the tapping means  14 , generally constituted by a pipe saddle and a stop cock, may form a releasable fastener system for mounting the first hose  16  and thus the chamber  18  on the pipe  12 . 
     As can be seen more clearly in  FIG. 2 , the chamber  18  is a tube of cylindrical section, preferably made of stainless steel or of polytetrafluoroethylene (PTFE), that is closed at both ends by respective leaktight couplings  181  and  182  enabling the space contained within the chamber  18  to be connected respectively to the first hose  16  and to the second hose  20 . 
     In addition, the chamber  18  contains capture means  22  for capturing odor- and/or taste-generating substances present in the water flowing in the pipe  12 . For this purpose, in the embodiment shown (see  FIGS. 2 ,  3 ,  6 , and  7 ), this capture means  22  comprises a support plate  221  having mounted on the back thereof a magnetic plate  222  that serves to hold the capture element  223  that acts by sorption of odor- and/or taste-generating substances by a magnetic effect, the capture element  223  being mounted on the other side of the support plate  221 . 
     The support plate  221  is preferably made of stainless steel and the magnetic plate  222  is covered in a layer  224  of Teflon or PTFE. 
     All of the materials of the chamber  18  and of the capture means  22  are selected to avoid releasing any substance that might hinder the capture of molecules responsible for taste and/or odors in water: specifically use is made of stainless steel, of glass, and/or of Teflon (registered trademark). 
     The magnetic plate  222  is preferably stapled to the support plate  221  and serves essentially to retain the sorption support  223  that includes the layer of polydimethylsiloxane (PDMS). 
     In the example shown, the capture element  223  acting by sorption is a traditional magnetic bar that is commercially available, comprising an elongate magnet coated in a sheath of glass and having a sleeve of polydimethylsiloxane (PDMS) mounted around the sheath of glass to form the sorption element proper. 
     As an alternative (not shown), the capture element  223  can be formed of a layer of polydimethylsiloxane (PDMS) connected by adhesive means to the support plate  221  like a patch (under such circumstances there is no need for the magnetic plate  221  nor for its layer  224  of PTFE, if any). 
     It can thus be understood that by passing water coming from the pipe  12  through the chamber  18 , substances that might be those responsible for the taste and/or odors of the water can be captured continuously by the capture means  22 . Such capture is performed so long as water flows through the chamber  18  going from the pipe  12  via the first hose  16  and then out from the chamber  18  prior to being discharge via the discharge second hose  20  to a drain. 
     It should be understood that the chamber  18  forms a contact chamber that may include a plurality of capture elements  223  acting by sorption that may be arranged in series or in parallel. 
     Likewise, it is possible to provide a plurality of chambers  18  in series or in parallel downstream from the tapping means  14  mounted on the pipe  12 . 
     After sufficient exposure to water coming from the distribution network via the pipe and the tapping means  14 , where this period is defined by the user, and/or possibly together with information documentation, the capture means  22  is extracted from the chamber  18  by opening at least one of the two couplings  181  and  182 , and then the capture element  223  acting by sorption is used for performing an analysis in order to detect the molecules responsible for the tastes and the odors of the water. 
     In the variant embodiment shown in  FIG. 4 , between the tapping means  14  and the chamber  18 , the first hose  16  is fitted with a flowmeter  24  and a gate valve  26 , in order to measure the rate at which water flows towards the chamber  18 , while also enabling this rate to be adjusted. 
     Furthermore, in  FIG. 4 , there is provided a system  30  for injecting a standard solution in parallel into the chamber  18 , the standard solution containing a known concentration of at least one well-identified molecule capable of being absorbed by the capture elements  223  acting by sorption. The standard solution is contained in a bottle  32 , itself connected to the first hose  16  via a pump  34  and possibly via a gate valve  26  associated with another flowmeter  38 . 
     Thus, in this configuration, the capture device  10  is fed with the standard solution contained in the bottle  32  by the pump  34  operating at a constant rate and adjusted as a function of the feed rate measured by the flowmeter  24  situated upstream from the chamber  18 , and also as a function of the concentration of the standard solution. 
     In another alternative embodiment, shown in  FIGS. 5 to 7 , it is possible to fasten the device  10  directly to the end of a faucet  40 . Under such circumstances, and as can be seen more clearly in  FIGS. 6 and 7 , instead of using the tapping means  14  and the first hose  16  to provide the hydraulic link and connection means between the chamber  18  and one end of the faucet  40 , a quick-coupling system  42  is used. 
     The quick-coupling system  42  as shown in  FIGS. 5 and 7  is constituted by an endpiece  421  pierced by a passage  422  with a bend, having an inlet suitable for receiving the free end of the faucet  40  and having the opposite end of the bend  422  communicating with the inside of the chamber  18 . 
     The chamber  18  is then closed at one of its ends (at the top in  FIG. 7 ) by a leaktight cap  183  replacing the leaktight coupling  182  of  FIG. 2 , while the other end of the chamber  18  (at the bottom in  FIG. 7 ) still has the leaktight coupling  181  that is used for discharging the water that has passed through the inside of the chamber  18 . 
       FIG. 8  shows a first other embodiment of the variant shown in  FIGS. 5 to 7  in which the device  10  is located directly at the end of a faucet  40 . Under such circumstances, the quick-coupling system  42  is a threaded coupling mounted on the chamber  18 ′ containing the capture means  22 ′ and including a support  221 ′ in the form of a housing tube provided with a plurality of through orifices, each capable of containing a capture element  223 ′. Each capture element  223 ′ is in the form of a hollow glass tube having its inside wall coated in a layer of polydimethylsiloxane (PDMS) with a fraction of the flow of water passing through the chamber  18 ′ at the outlet from the faucet  40  flowing thereover. 
     In  FIG. 8 , seven hollow glass tubes forming respective capture elements  223 ′ are housed in seven support orifices  221 ′. Nevertheless, it should be understood that it is possible to provide a support  221 ′ with a number of orifices that is larger or smaller than seven, or indeed that it suffices for at least one of the support orifices  221 ′ to house a capture element  223 ′ in order for the device  10  to function, i.e. to capture odor- and/or taste-generating substances present in the water flowing through the device  10 . In  FIG. 8 , a tap-nozzle  186  is situated at the bottom portion of the chamber  18 ′. 
     In this first solution shown in  FIG. 8 , when it is desired to characterize the odor- and/or taste-generating substances that have been collected on the layer of polydimethylsiloxane (PDMS) coating the inside walls of the hollow glass tubes forming the capture elements  223 ′, it suffices to remove the support  221 ′ and remove at least one of the hollow glass tubes forming the capture elements  223 ′ prior to performing the analysis. 
       FIG. 9  shows a second other embodiment of the variant shown in  FIGS. 5 to 7 , in which the device  10  is directly connected to the end of a faucet  40 . As can be seen in  FIG. 9 , the chamber  18 ″ is connected to the endpiece of the faucet  40  via a suitable quick-coupling system  42  and it is in the form of a drum, the chamber  18  operating on the principle of a water mill by virtue of the capture means  22 ″ that comprises:
         a rotary shaft  221 ″ suitable for turning relative to the chamber  18 ″ in a direction orthogonal to the flow direction of water from the faucet  40 , being offset from the flow axis of the water leaving the faucet  40 ; and   blades  223 ″ mounted on the rotary shaft  221 ″ and covered in a layer of polydimethylsiloxane (PDMS) at least on the face over which the water passing through the chamber  18 ″ flows at the outlet from the faucet  40 .       

     It will be understood that the rotary shaft  221 ″, serves as a support for the blades  223 ″ which themselves form the moving capture elements  223 ″ that act by sorption. 
     In this second solution shown in  FIG. 9 , when it is desired to characterize the odor- and/or taste-generating substances that have been collected by the layer of polydimethylsiloxane (PDMS) on the blades  223 ″, it suffices to replace the chamber  18 ″ with another chamber  18 ″, or else it is possible to make provision for opening the chamber  18 ″ and changing either one or more of the blades  223 ″, or else the assembly formed by the support shaft  221 ″ and the blades  223 ″.