METHOD AND SYSTEM FOR THE ANALYSIS OF A LIQUID CONTAINING SUBSTANTIAL MATTER

Abstract

The method for analyzing a liquid sample containing suspended matter is implemented automatically by means of a processing unit using a plurality of digital images (Ii) of said sample at rest, which were captured by means of an image capture device, over a period of time and at successive instants with a time interval between two successive digital images. The method comprises (a) the digital cutting of an analysis window (F) of the sample from each digital image (Ii), in the form of a strip (Bi) having a height (H) and a width (L), and (b) the automatic construction of a final digital image (IM) by chronologically aligning and juxtaposing the plurality of strips (Bi) in the direction of their width. Fig. 3

Description

Title of the invention: METHOD AND SYSTEM FOR ANALYZING A LIQUID CONTAINING SUSPENDED MATERIALS Technical field

[0001] The present invention relates to the analysis of a sample of liquid containing suspended matter (solid and / or colloidal). It mainly finds its application in the field of water treatment, in particular domestic or industrial wastewater. Prior art

[0002] The treatment of wastewater (domestic or industrial) aims to decontaminate wastewater in order to obtain purer water that can be reused or complies with regulations for discharge into the natural environment.

[0003] More particularly, it is usual to treat wastewater by a biological treatment process, called "activated sludge", which uses biological purification by bacteria. In the wastewater treatment sector, this activated sludge process is part of the so-called "secondary" treatments.

[0004] This process consists of mixing the wastewater to be treated with a medium rich in bacteria in a biological treatment basin, also commonly called a "biological reactor" or "aeration basin" and aerating the mixture, typically by adding air, in order to cause the bacteria to degrade the organic compounds present in the wastewater and which are harmful to the environment. This degradation increases the bacterial population, known as "sewage sludge" or "purifying sludge" and induces the production of small, non-harmful molecules such as CO2, H2O or N2.

[0005] The wastewater loaded with undissolved sludge in suspension, also commonly called "mixed liquor", is then treated in a clarifier, in which the sludge is separated from the purified water by decantation in a settling tank or conversely by flotation in a flotation tank with injection of air bubbles.

[0006] This type of biological treatment is generally used to treat domestic wastewater. Secondary treatment of domestic wastewater is most often carried out in a "biological" manner, but a "physicochemical" route can replace it or be added to it. It can also be used to treat industrial wastewater, for example in the food industry.

[0007] To treat industrial wastewater, for example in the paint and ink production industries, it is also possible to implement a chemical purification process allowing coagulation or flocculation of pollutants in treated wastewater, followed by a physical clarification step in a clarifier by decantation or flotation.

[0008] As an alternative to the aforementioned traditional treatments, the SBR process ("Sequencing Batch Reactor") is also known, which is an activated sludge treatment process by sequential feeding of the effluent to be treated. All the purification stages (aerobic, anoxic and sedimentation phases) are successively carried out in a single reactor. The SBR system thus uses a single basin in which a treatment cycle is carried out, which can generally be composed of five stages: filling the tank, the reaction during which aerobic and anoxic phases alternate, settling, purging, rest and sludge withdrawal.

[0009] The above-mentioned treatment processes may be subject to various malfunctions which affect the purification performance and the ability of suspended matter to settle or float.

[0010] It is currently common practice to control or monitor the operation of a treatment plant by analyzing in a laboratory or internally the ability to settle suspended matter, and in particular purification sludge, on a sample taken from a test tube in order to assess the morphological and hydrodynamic characteristics of the suspended matter contained in the liquid phase, in particular their ability to sediment, the colors of the different resulting liquid layers, and the appearance at the liquid interfaces (clear interface or diffuse interface). During this sampling, the operator must, on the one hand, ensure the homogeneity of the liquid medium in order to obtain a representative sample, and on the other hand, ensure adequate storage conditions to limit alteration of the sample.

[0011] In the laboratory, the measurements are carried out according to various protocols making it possible to establish characteristic indices recognized by those skilled in the art, such as the sludge index, the Mohlman index, the settling speed, etc.

[0012] However, using laboratory analysis is a time-consuming practice with possible deviant results. To carry out these tests, manufacturers must have an in-house laboratory and the skills or call on an external service provider. In both cases, handling the sample is a preliminary step, and it involves certain risks for the operator, particularly when the liquid is biologically complex (contamination, infection), or when the sampling points are difficult to access (risk of falling, drowning) due to restrictive infrastructure: high or buried tank, confined space, moving metal mass, proximity to the liquid mass, etc. This also represents an increased probability of errors in the final result due to the methods of collecting and preserving samples.

[0013] These inherent operational risks associated with a significant mobilization of resources have encouraged treatment plant managers to use continuous measuring devices integrated into the process.

[0014] To date, for monitoring the sedimentation of suspended matter on an industrial site, a method is known, which is described for example in American patent application US2009 / 0095070, and which aims to determine the position of the liquid-solid interphase (sludge blanket) by means of an ultrasonic probe immersed in a settling basin of the treatment plant.

[0015] A second method, which is described for example in European patent EP0114408, also aims to determine the position of the sludge blanket within a settling basin by means of a diving body equipped with an image capture device.

[0016] Integrated into the heart of the hydraulic process (decanter, clarifier, etc.), the two aforementioned technologies make it possible to monitor the behavior of the phase (biological sludge) in relation to the liquid phase, in its real conditions of evolution (in particular its ability to settle), with the advantage of thus being able to detect malfunctions of the process as a whole. On the other hand, this type of continuous measuring device is clearly different from a laboratory analysis, such as the settling test in a test tube. These devices are therefore not able to deliver indices or graphs listed in the scientific literature and representative of the behavior of the liquid, such as the ability to settle according to a protocol test, or the inherent settling speed.Furthermore, immersing a measuring probe or an image capture device in liquid complicates the implementation of the method, in particular by imposing sufficient sealing constraints to protect the measuring probe or the image capture device.

[0017] An automated system for characterizing particles suspended in a liquid has also already been proposed in US patent US 8,506,799, in particular in a liquid sample taken in a coagulation-flocculation pretreatment step implemented in a purification process by sedimentation, flotation, membrane filtration, and in particular in the treatment of wastewater. The sample can be taken automatically and isolated in a bypass of the treatment basin (Fig. 81) equipped with a device for capturing a plurality of successive images of this sample.This characterization system allows to automatically analyze, by image processing, the images of the sample and to automatically determine geometric properties of the particles, in order to calculate characteristics of floc particles such as: volume concentration, number concentration, gravitational sedimentation velocity, mass density, mass concentration, particle volume and particle diameter.

[0018] A technical solution for automatically analyzing the sedimentation characteristics of a liquid containing suspended matter, such as wastewater treated in a biological purification process, has also already been proposed in Chinese patent application CN 111796552. This technical solution is based on processing successive cycles of a sample of liquid at rest, which has been taken from a transparent vertical observation tube connected to the treatment basin. This image processing is based on a module for analyzing each image which has been specifically developed in a Matlab programming environment. Presentation of the invention

[0019] The invention aims to propose a new technical solution for analyzing a sample of liquid containing materials (solid and / or colloidal) in suspension.

[0020] This new technical solution can more specifically and mainly be used in the field of treatment of domestic or industrial wastewater, to analyze a sample of water loaded with suspended matter which has been taken from a treatment plant, in particular a biological treatment plant.

[0021] This new technical solution can also be used in the field of drinking water to analyze a liquid loaded with suspended matter and taken from a drinking water treatment process, in particular a surface water treatment process (SWP), or can also be used to analyze an effluent from a process liquid, which is used during the implementation of an industrial process and which becomes loaded with suspended matter during its use. Summary of the invention

[0022] The invention thus has as its first object a method for analyzing a sample of liquid containing suspended matter, said method being implemented automatically by means of a processing unit, from a plurality of digital images of said sample at rest which have been captured by means of an image capture device, over a period of time (T) and at successive instants with a time interval (AT) between two successive digital images, said method comprising (a) the digital cutting in each digital image (h) of an analysis window (F) of the sample, in the form of a strip (B;) having a height (H) and a width (L) and (b) the automatic construction of a final digital image, by aligning and chronologically juxtaposing the plurality of strips in the direction of their width.

[0023] The time period (T) is more particularly sufficient to observe at least the start of sedimentation, and preferably complete sedimentation, of the materials suspended in the sample.

[0024] The digital image constructed automatically by the processing unit advantageously allows a rapid and synthetic visualization of a sedimentation profile over time of the materials suspended in the sample which was taken.

[0025] The automatic construction of this image by the processing unit is simple to implement and does not require significant computing power,

[0026] Each constructed digital image can be used, as is, to visually and quickly monitor the evolution over time of sedimentation in the sample taken. In this case, each constructed digital image is, for example, displayed on a control screen or is printed in situ at the site where the sample was taken, preferably in an automated manner, or can be transmitted remotely for viewing to a remote site and / or to a mobile communication device, such as a mobile phone or equivalent.

[0027] When the sample has been taken from an industrial or domestic wastewater treatment plant, this visual inspection allows, for example, the manager and / or operator of this treatment plant to check punctually or monitor over time the proper progress of the treatment process and to detect any malfunctions.

[0028] Each final digital image can also be processed automatically by a specific image processing computer program.

[0029] The successively constructed digital images can also be advantageously stored in an electronic memory, for example in a memory of a computer server in order to keep a history of operation of the treatment installation, for example an industrial or domestic wastewater treatment plant, in which each sample was preferably taken in an automated manner.

[0030] More particularly, the analysis method of the invention may comprise the following additional and optional characteristics, each additional and optional characteristic being able to be combined with any of the other additional and optional characteristics: - The method comprises the automated capture of the plurality of digital images of said sample at rest using the image capture device. - Digital images are in color. - The method includes the collection, preferably automated, and the resting of the sample to be analyzed. - The sample is taken and left to rest in a tube that is at least partly transparent, and preferably in a tube with a circular section. - The time period (T) is between 15 minutes and 5 hours, and / or can be adjustable. - The time interval (AT) is preferably between 10s and 60s, and / or can be adjustable. - The liquid sample containing suspended matter was taken in a liquid purification process comprising at least one biological purification stage using activated sludge during which the liquid becomes loaded with suspended matter and / or in a liquid purification process during which flocculation and / or coagulation of suspended matter contained in the liquid is carried out by physical and / or chemical means. - The liquid sample containing suspended matter was taken from a biological activated sludge treatment basin of a treatment plant or at the outlet of this basin or from a coagulation and / or flocculation basin or at the outlet of this basin or more particularly from an anoxia basin or at the outlet of this basin. - The liquid loaded with suspended matter is domestic or industrial wastewater. - The liquid loaded with suspended matter is taken from a drinking water treatment process, in particular a surface water treatment process (SWP). - the liquid loaded with suspended matter is an effluent from a process liquid which is used during the implementation of an industrial process.

[0031] The second subject of the invention is a method for controlling or monitoring a process for purifying a liquid comprising at least one treatment step during which the liquid becomes loaded with suspended matter, preferably a biological purification step using activated sludge and / or comprising at least one treatment step during which flocculation and / or coagulation of suspended matter contained in the liquid is carried out by physical and / or chemical means. Typically, a sample of liquid containing suspended matter is taken and this sample is left to stand and said sample at stand is analyzed using the above-mentioned analysis method.

[0032] The third subject of the invention is a system for analyzing a liquid loaded with suspended matter, said system comprising a sampling and acquisition system and an image processing device; the sampling and acquisition system is adapted to automatically take a sample of liquid containing suspended matter and to put this sample to rest and to carry out an automated capture of a plurality of successive digital images of the sample taken, over a period of time (T) and at successive times with a time interval (AT) between two successive digital images; the device image processing is adapted to automatically construct a final image, from the plurality of successive digital images of the sample taken and by implementing the aforementioned analysis method.

[0033] The fourth subject of the invention is an image processing device comprising a memory in which are stored a plurality of digital images of a sample of liquid at rest containing suspended matter, which digital images were captured over a period of time (T) and at successive instants with a time interval (AT) between two successive digital images; the device is configured, and preferably programmed, to automatically construct a final image, from the plurality of successive digital images of the sample and by implementing the above-mentioned analysis method.

[0034] The fifth subject of the invention is a computer program product comprising program code instructions and making it possible, when executed by at least one processing unit, to carry out the above-mentioned analysis method. Brief description of the drawings

[0035] The characteristics and advantages of the invention will appear more clearly on reading the detailed description below of a preferred embodiment of the invention with reference to the appended drawings in which: - [Fig.l] [Fig.l] schematically presents in the form of a block diagram a water treatment station equipped with an analysis system of the invention. - [Fig.2] [Fig.2] schematically represents a digital image (I; ) of a sample showing the analysis window. - [Fig.3] [Fig.3] schematically represents the specific image processing of the invention. Detailed description

[0036] [Fig. 1] schematically shows a non-limiting example of the invention of a wastewater treatment plant S, which is equipped with a system 1 for analyzing a liquid (wastewater) which is taken from the treatment plant S and which is loaded with suspended matter. S wastewater treatment plant

[0037] The purification station S is known per se and usually comprises from upstream to downstream: - an SI screen, which removes coarse matter from incoming wastewater (rags, pieces of wood, plastics, leaves, etc.); - a S2 sand removal and degreasing basin; - a biological treatment basin S3, in which a activated sludge treatment process, - an S4 clarifier.

[0038] In the biological treatment tank S3, the wastewater from the grit and grease removal tank S2 is usually mixed in the biological treatment tank S3 with a medium rich in bacteria, and the mixture is aerated by an air supply. The bacteria degrade the organic compounds, which are present in the wastewater and which are harmful to the environment, and transform them into sewage sludge. This sewage sludge in free culture naturally forms more or less dense flocs. The wastewater is thus loaded with undissolved suspended matter (sludge), this sludge being made up of inorganic and organic particles in the colloidal or particulate state.

[0039] This sludge-laden wastewater, also commonly called “mixed liquor”, is then treated in the S4 clarifier, in which the sludge is separated from the purified water, either by settling in a settling tank, or conversely by flotation in a flotation tank with injection of ascending air bubbles.

[0040] When clarification is carried out by flotation, the treatment plant S may include, upstream of this flotation basin, a system for injecting chemical agents allowing coagulation-flocculation of suspended matter in the wastewater from the biological treatment basin S3.

[0041] A significant portion (typically > 90%) of the treated and recovered sewage sludge is recycled into the biological treatment tank S3 to maintain the biological purification process by the bacteria.

[0042] At the outlet of the clarifier S4, the purified treated water can be at least partly reused and / or can be discharged into the natural environment.

[0043] Preferably, but optionally, when it is intended to be reused, the purified treated water leaving the clarifier S4 can be subjected, in an optional installation S5, to one or more additional decontamination treatments called tertiary, such as for example, a treatment by UV radiation and / or a chlorination treatment and / or an ozone treatment. Analysis system 1

[0044] The analysis system 1 comprises an automated system 10 for collecting and acquiring images and a processing device 11.

[0045] Automated image collection and acquisition system 10

[0046] The automated image collection and acquisition system 10 comprises: - a hydraulic sampling device 100 - an image capture device 101, and - a processing unit 102 configured to automatically control the hydraulic sampling device 100 and the device image capture 101.

[0047] Preferably, this processing unit 102 can also communicate with a human-machine interface (HMI), in order to allow an operator to manually enter commands.

[0048] More particularly, the hydraulic sampling device 100 comprises an upstream pipe 100a equipped with a pump 100b, a vertical and transparent tube 100c, which forms a chamber 100d for resting and observing a sample and a downstream pipe 100e.

[0049] When the hydraulic sampling device 100 is under load, the pump 100b can be removed and possibly can, for example, be replaced by a valve, in particular a solenoid valve.

[0050] Preferably, but not necessarily, the tube 100c has a circular cross-section in order to facilitate fluid flow by minimizing soiling of the inner face of the inner wall of the tube 100c.

[0051] The upstream pipe 100a is connected at its upstream end to the biological treatment basin S3 and at its downstream end to the chamber 100d for resting and observing a sample, preferably by being connected to the lower end of the tube 100c, in order to allow filling from the bottom of this tube.

[0052] The downstream pipe 100e is connected at one end to the chamber 100d for resting and observing a sample, preferably at the upper end of the tube 100c, and at its other end to the biological treatment basin S3, in order to allow a return to this basin S3 of the sample taken.

[0053] The image capture device 101 is preferably a photographic camera or photographic sensor allowing each acquisition command to capture a unitary 2D digital image. The image capture device 110 may also be a digital camera allowing a video stream of 2D digital images to be captured.

[0054] The image capture device 101 is placed opposite the tube 100c and at a distance allowing the optics of this device to cover at least the entire chamber 100d for resting and observing a sample.

[0055] Preferably, the chamber 100d for resting and observing a sample is illuminated and / or backlit by means of a light source, to improve the quality of the captured images.

[0056] The resolution of the image capture device will be adapted on a case-by-case basis by those skilled in the art depending on the desired resolution for the captured images.

[0057] The image capture device 101 may be adapted to capture digital images of the sample in grayscale or black and white.

[0058] Preferably, the image capture device 101 makes it possible to capture images

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] digital in color. The processing unit 102 can be implemented with various technologies and is preferably a programmable electronic processing unit, for example of the microcomputer type, programmable automaton, electronic card with microprocessor(s) or microcontroller(s) or electronic card with programmable electronic circuit(s) of the FPGA type. The processing unit 102 is configured to automatically execute a program for taking a sample and acquiring a plurality of successive images of this sample. This program is for example stored in an electronic memory of the processing unit 102. When executed by the processing unit 102, this program allows the processing unit 102 to control the pump 100b of the hydraulic sampling system 100 and the image capture device 101 so as to automatically carry out, each time a sample is taken, the following cycle of successive operations: 1. the processing unit 102 controls the starting of the pump 100b, so as to take, from the biological treatment basin S3, liquid homogeneously loaded with suspended matter and to fill the tube 100c with a sample of this loaded liquid; 2. the processing unit 102 controls the image capture device 101, so as to capture a plurality (N) of successive digital images I; (Ii, I2, I3,... IN) including the sample at rest contained in the tube 100c, for a period of time T sufficient to observe sedimentation of the materials suspended in the sample, and at successive instants with a time interval AT [T=(N-1).AT]. 3. Once the image capture is complete, the processing unit 102 controls the pump 100b for a given time so as to evacuate the sample into the basin 3 and to circulate liquid in the tube 100c to wash the internal face of this tube, then the electronic processing unit 102 controls the stopping of the pump 100b so as to stop the circulation of liquid and to obtain a clean tube 100c, which is ready for the next sampling. The acquisition period T is preferably adjustable and is chosen in practice mainly depending on the nature of the liquid and the sedimentation rate of the suspended matter. In a non-limiting manner to the invention, this acquisition period T can generally be between 15 minutes and 5 hours. More particularly for a domestic wastewater treatment process typically having an average settling speed of around 60cm / h, this period acquisition period T will for example be set between approximately 30 minutes and 45 minutes. For an industrial wastewater treatment process typically having a lower average settling speed, this acquisition period T will for example be set between approximately 1.5 hours and 5 hours.

[0066] The aforementioned time interval AT is preferably identical throughout the acquisition period of the N digital images I; of a sample [T=(N-1). AT].

[0067] The time interval AT is preferably adjustable and in practice conditions the resolution of the final digital image IM.

[0068] In a non-limiting manner of the invention, the time interval AT can for example be set between 10s and 60s, and preferably can be of the order of 30s.

[0069] The aforementioned image acquisition sampling cycle h may for example be triggered by a command which is entered manually by an operator by means of the HMI interface, for example when the operator wishes to carry out a one-off check of the operation of the treatment plant S.

[0070] The treatment unit 102 can also be programmed to carry out this cycle automatically in a repetitive and periodic manner (for example several times per day), as part of continuous monitoring of the operation of the treatment plant S.

[0071] At the end of each image acquisition sampling cycle f, the images f captured during the cycle can be stored in a memory (local or on a remote server) which can be accessed by the image processing device 11 and / or are sent by the processing unit 102 to the image processing device 11.

[0072] [Fig.3] shows an example of three images Ib I30 and I60 extracted from the capture of 60 (N=60) successive images of a sample, with for example a time interval AT of 30 seconds between images.

[0073] In the first image Ib the turbidity of the liquid is significant, and the sludge veil V which has formed is located in the upper part of the sample. Then, under the effect of sedimentation, this sludge veil V moves towards the bottom of the sample (I30; 1®) at a more or less significant speed characteristic of the sedimentation speed. Image processing device 11

[0074] The image processing device 11 comprises an image processing unit 110, which is configured to digitally and automatically process the plurality of images I; resulting from each aforementioned cycle, in order to construct a final image IM.

[0075] This image processing unit 110 can be implemented with various technologies and is preferably a programmable processing unit, for example of the microcomputer type, electronic card with microprocessor(s) or microcontroller(s) or electronic card with programmable electronic circuit(s) of the FPGA type.

[0076] The image processing device 11 can be positioned on the site of the treatment plant near the automated image sampling and acquisition device 10. In this case, the image processing unit 110 can be integrated into the aforementioned processing unit 102.

[0077] The image processing device 11 can also be transferred to another remote site. In this case, the processing unit 102 is designed to transmit to the image processing device 11 the plurality of images I; resulting from each aforementioned cycle.

[0078] The image processing unit 110 of the device 11 is configured to automatically execute an image processing program which is specific to the invention and which is for example stored in an electronic memory of the image processing unit.

[0079] This image processing program can be executed by the image processing unit 110, either once the acquisition of the images h of the sample is finished, or preferably for a gain in processing speed, in masked time as the successive images L are acquired.

[0080] When executed by the image processing unit 110, this program allows the image processing unit 110 to automatically construct, for each sample, and from the successive digital images h of this sample, a final digital image IM which allows rapid visualization of the evolution over time of the morphological and hydrodynamic characteristics of the materials suspended in the sample.

[0081] Preferably, the image processing device 11 also comprises a screen 111 allowing the processing unit 110 to display each final image IM, preferably in color, for visual examination by an operator. The image processing device 11 may also comprise a printer 112 allowing the image processing unit 110 to print on paper, preferably in color, each final image IM for visual examination by an operator.

[0082] Preferably, the image processing device 11 also comprises a memory 113 in which the processing unit 110 can store the history of all the final images IM successively constructed.

[0083] The image processing device 11 may also include a telecommunications module 114 enabling it to transmit each final digital image IM to a remote computer server and / or to a mobile communications device such as a cell phone or digital tablet.

[0084] More particularly, the above-mentioned image processing program makes it possible, when executed by the image processing unit 110, to automatically carry out (a) a digital cutting operation of each digital image h of the sample under the form of strips B; and (b) a digital collage operation allowing the construction of the final image IM, from the digital strips B;.

[0085] (a) cutting

[0086] The digital cutting operation consists of digitally cutting out, in each image f, a predefined analysis window F ([Fig.2]) of the sample, in the form of a strip B; ([Fig.3]) preferably rectangular, of height H and width L. This analysis window F is identical for all the images I;.

[0087] This analysis window F preferably extends over the entire height of the sample and preferably over a limited width of the sample ([Fig.2]).

[0088] More particularly, the digital strips B; have the same height H and the same width L.

[0089] (b) construction of the final image IM

[0090] The digital collage operation consists of aligning and chronologically juxtaposing ([Fig.3]) the plurality of strips (B;) in the direction of their width, so as to obtain the final digital image IM, such as that illustrated as an example in [Fig.3].

[0091] With reference to [Fig. 3], the final digital image IM which is obtained advantageously constitutes a graph making it possible to visualize in a synthetic manner the evolution over time of the morphological and hydrodynamic characteristics of the suspended matter (purification sludge) contained in the liquid phase, in particular their ability to sediment and their sedimentation profile over time, the colors of the different resulting liquid layers, and the appearance at the liquid interfaces (clear interface or diffuse interface).

[0092] The graph (final image IM) or the succession of periodic graphs IM thus constitutes a new analysis tool which can advantageously be used by an operator or manager of the treatment plant to punctually check or to continuously monitor the proper functioning of the treatment plant and to detect one or more malfunctions.

[0093] The IM graph can be used to measure different parameters, such as settling speed, sludge color, sludge blanket quality V, sludge index, Mohlman index.

[0094] In the case of use of the device during the pilot test phase of the treatment plant, the IM graph can also be used to determine with greater precision the size of the clarifier, it being recalled that to date, for the definition of the dimensions of the clarifier, theoretical data on settling speed are used.

[0095] This graph (final image IM) can also be used by an operator or manager of the treatment plant, by carrying out a simple visual examination. allowing visual control, for example, that the sedimentation profile over time is correct or dysfunctional and characteristic of a problem in the operation of station S.

[0096] This visual examination can more particularly make it possible to detect a certain number of malfunctions of the treatment plant S, such as: a total absence of decantation a slowdown in the settling speed the presence of free jibs in the clarified phase above the sludge blanket V the appearance of floaters a rise of mud significant turbidity in clarified water resulting in a reduction in transparency an absence of a clear interface between the clarified and sedimented phases a blackening or lightening of the sludge an abnormally large volume of settled sludge a gas emanation

[0097] The periodic production of IM graphs makes it possible to identify, where appropriate, cyclical or specific periods of biological destabilization within basin 3, with a view to searching for the causes upstream, at the level of wastewater production.

[0098] The analysis of this IM graph or of the succession of periodic IM graphs can be used to apply corrective measures to the treatment plant or to optimize the operation of the treatment plant, such as for example by reducing the quantity of air blown into the biological treatment basin 3 for energy saving purposes, while ensuring that the biological sludge retains morphological characteristics favorable to the clarification process. Improved variant

[0099] In a non-limiting manner of the invention, in an improved variant embodiment, the image processing device 11 can also be programmed to automatically analyze each final image IM: by calculating from each final IM image operating parameters, such as settling speed, sludge color, sludge blanket quality V, sludge index, Mohlman index.

[0100] and / or by automatically detecting the aforementioned malfunctions, by automatically detecting a malfunction of the treatment plant S, from a comparison of each image IM with several images stored in memory and characteristic of proper operation of the plant S. purification

[0101] The analysis system 1 of the invention can also be integrated into a control loop making it possible, from the final digital images IM, to automatically adjust one or more operating parameters of the purification station S; such as for example the flow rate of wastewater supply at the inlet of the station, the flow rate of aeration in the basin S3, where appropriate the flow rate of the ascending air injected in the form of bubbles into a flotation basin of the clarifier S4, etc. Other application examples

[0102] The invention is not limited to the analysis of a sample taken from a biological treatment basin S3 or at the outlet of this basin.

[0103] In the case of a biological treatment plant, sampling can be carried out at any point in the plant where there is water loaded with suspended matter.

[0104] Furthermore, the invention can be used to analyze a sample taken in a process for purifying a liquid, and in particular water, during which flocculation and / or coagulation of suspended matter contained in the liquid is carried out by physical and / or chemical means.

[0105] The invention can also be used in the field of drinking water, in a surface water purification treatment process (SWP) using in particular one or more filter membranes, in order to analyze water samples taken upstream of the membrane filtration.

[0106] The invention can also be used to analyze an effluent of a process liquid, which is used for the implementation of an industrial process and which becomes loaded with suspended matter during its use.

[0107] The invention can also be used during the pilot test to analyze the effluent and size the clarifier.

Claims

Claims

1. Method for analyzing a sample of liquid containing suspended matter, said method being implemented automatically by means of a processing unit (110) from a plurality of digital images (h) of said sample at rest, which have been captured by means of an image capture device (101), over a period of time (T) and at successive instants with a time interval (AT) between two successive digital images, said method comprising (a) digitally cutting out in each digital image (f) an analysis window (F) of the sample, in the form of a strip (B; ) having a height (H) and a width (L) and (b) automatically constructing a final digital image (IM), by aligning and chronologically juxtaposing the plurality of strips (B;) in the direction of their width.

2. The method of claim 1 comprising the automated capture of the plurality of digital images (h) of said sample at rest by means of the image capture device (101).

3. A method according to any one of claims 1 or 2, wherein the digital images (h) are in color.

4. Method according to any one of claims 1 to 3, comprising the collection, preferably automated, and the resting of the sample to be analyzed.

5. Method according to claim 4, in which the sample is taken and placed at rest in a tube (100c) at least partly transparent, and preferably in a tube with a circular section.

6. Method according to any one of claims 1 to 5, in which the time period (T) is adjustable and / or is between 15 minutes and 5 hours.

7. Ull. Method according to any one of claims 1 to 6, in which the adjustable time interval (AT) and / or is between 10s and 60s.

8. Method according to any one of claims 1 to 7, in which the liquid sample containing suspended matter has been taken in a liquid purification process comprising at least one biological purification step using activated sludge during which the liquid becomes loaded with suspended matter and / or in a liquid purification process during which flocculation and / or coagulation of suspended matter is carried out by physical and / or chemical means. contained in the liquid.

9. Method according to claim 8, in which the liquid sample containing suspended matter was taken from a biological activated sludge treatment basin (S3) of a treatment plant (S) or at the outlet of this basin or from a coagulation and / or flocculation basin or at the outlet of this basin or from an anoxia basin or at the outlet of this basin.

10. Method according to any one of claims 1 to 9, in which the liquid loaded with suspended matter is domestic or industrial wastewater, or in which the liquid loaded with suspended matter is taken from a drinking water treatment process, in particular a surface water treatment process (SWP), or in which the liquid loaded with suspended matter is an effluent from a process liquid which is used during the implementation of an industrial process.

11. Method for controlling or monitoring a process for purifying a liquid comprising at least one treatment step during which the liquid becomes loaded with suspended matter, preferably a biological purification step using activated sludge and / or comprising at least one treatment step during which flocculation and / or coagulation of suspended matter contained in the liquid is carried out by physical and / or chemical means, characterized in that a sample of liquid containing suspended matter is taken and this sample is left to stand and in that said sample is analyzed at stand by implementing the analysis method of any one of claims 1 to 10.

12. System (1) for analyzing a liquid loaded with suspended matter, said system (1) comprising a sampling and acquisition system (10) and an image processing device (11), the sampling and acquisition system (10) being adapted to automatically take a sample of liquid containing suspended matter and to put this sample to rest and to carry out an automated capture of a plurality of successive digital images (f) of the sample taken, over a period of time (T) and at successive times with a time interval (AT) between two successive digital images, and the image processing device (11) being adapted to automatically construct a final image (IM), from the plurality of successive digital images (h) of the sample taken and by implementing the method referred to in any one of claims 1 to 10.

13. Image processing device (11) comprising a memory in which are stored a plurality of digital images (I;) of a sample of liquid at rest containing suspended matter, which digital images (I;) were captured over a period of time (T) and at successive instants with a time interval (AT) between two successive digital images, the device being configured, and preferably programmed, to automatically construct a final image (IM), from the plurality of successive digital images (h) of the sample and by implementing the analysis method referred to in claim 1.

14. Computer program product comprising program code instructions and allowing, when executed by at least one processing unit, to carry out the analysis method of any one of claims 1 to 10.

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