Method for the real-time monitoring of a drinking water production plant; and associated system and computer program

Abstract

The invention relates to a method (100) that consists in: defining (120) a target indicator of how effectively a pathogen is removed by the treatment carried out by the drinking water production plant from raw water on the basis of a microbiological analysis of the raw water and a sanitary safety constraint for the drinking water; and, at each time of the operation of the plant, acquiring (130, 140) an instantaneous value for at least one operating parameter of each unit process in the treatment; determining (150) an instantaneous unit indicator of how effectively the pathogen is removed by each unit process from the instantaneous value of the operating parameter of the considered unit process and a model of this unit process; aggregating (155) the instantaneous unit indicators to obtain an instantaneous total indicator relating to how effectively the pathogen is removed by the processing performed by the plant; comparing (160) the instantaneous total indicator and the target indicator to detect non-compliance.

Description

[0001] Method for real-time monitoring of a drinking water production plant; associated system and computer program.

[0002] The invention relates to the general field of drinking water production, and to the particular field of methods and systems for monitoring the industrial process of treating raw water in order to produce drinking water.

[0003] A production plant implements a treatment comprising a series of unit processes to ensure control of microbiological risks linked to the various pathogens present in raw water.

[0004] Water is considered potable when it meets various microbiological criteria, such as the absence of Escherichia coli and enterococci.

[0005] Historically, the management of drinking water quality has relied on microbiological analyses, carried out in the laboratory, of the water produced at the outlet of the production plant, i.e. after the water has been produced and distributed as drinking water.

[0006] This "a posteriori" approach has several limitations: insufficient volumes analyzed, insufficient frequency of analysis, microorganisms sought not reflecting all the pathogens potentially present, time between sampling and delivery of results too long.

[0007] This is therefore a reactive approach, which can help to characterize contamination that has already occurred, but which is insufficient to ensure the health safety of the water produced.

[0008] An alternative "a priori" approach has been proposed. It is based on a "quantitative microbiological risk assessment" - EQRM.

[0009] The EQRM is based on the results of laboratory analyses of contaminants in raw water, not drinking water.

[0010] EQRM also relies on historical operating data from the production plant.

[0011] This information makes it possible to assess health risks and to propose limits on the effectiveness of the unit processes of the treatment carried out. These limits must ensure a priori control of health risks.

[0012] This approach helps to achieve the recommendations of the World Health Organization.

[0013] But, particularly in the case of a complex production plant, the limits on the efficiency of unit processes prove to be too safe and generate unnecessary operating constraints. Indeed, since the operating data of the production plant are used through a history to calculate the limits of each unit process, not only is the temporal evolution of these data not taken into account, but also the proposed limits do not take into account the compensation phenomena that can take place between unit processes.

[0014] In other words, the efficiency of each unit process is evaluated individually and separately from that of the other unit processes, and for safety, the worst case over the historical period considered is retained to define the operating point of a particular unit process.

[0015] There is therefore a need for a monitoring process that respects the EQRM approach to health risk, but which is more flexible in use.

[0016] The purpose of the present invention is to meet this need.

[0017] For this purpose, the subject of the invention is a method for real-time monitoring of a plant for producing drinking water from raw water, the production plant implementing a treatment comprising at least two unit processes successive to one another, the monitoring method comprising the steps consisting of: defining a target indicator relating to an efficiency of elimination of at least one pathogen by the treatment implemented by the production plant, taking into account the results of a microbiological analysis of a concentration of the pathogen in the raw water and a health safety constraint on a concentration of the pathogen in the drinking water; and, at each instant of operation of the production plant, acquiring an instantaneous value of at least one operating parameter of each unit process of the treatment;determine an instantaneous unit indicator relating to the effectiveness of pathogen elimination by each unit process of the treatment from the instantaneous value of the operating parameter of the unit process considered and a model of the unit process considered; aggregate the instantaneous unit indicators determined for each unit process to obtain an instantaneous total indicator relating to the effectiveness of pathogen elimination by the treatment implemented by the production plant; compare in real time the instantaneous total indicator and the target indicator to detect non-compliance; and in the event of detection of non-compliance, generate an alert.;

[0018] According to particular embodiments, the method comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0019] - the acquisition step comprises a step (130) consisting of measuring a plurality of raw values ​​of the operating parameter of the unit process considered by means of one or more suitable sensors, and a step (140) consisting of preprocessing the plurality of raw values ​​measured to obtain the instantaneous value of the operating parameter of the unit process considered.

[0020] - the step of preprocessing the plurality of measured raw values ​​consists of averaging the raw values ​​over a predefined time interval.

[0021] - the method comprises an analysis step during which the microbiological analysis of the raw water is carried out, the analysis step being carried out regularly, in the laboratory or automatically, to update the results used in the step of defining the target indicator.

[0022] - the method comprises a step of displaying, on a screen of a human-machine interface, each instantaneous unit indicator, the instantaneous total indicator, a result of the comparison step, and / or the alert when it is generated.

[0023] - the method further comprises a step of defining an operating point of at least one of the unit processes of the treatment from a result of the comparison step.

[0024] - the method further comprises a control step consisting of calculating a setpoint value of at least one control quantity of at least one unit process of the treatment from the operating point defined for the unit process of treatment considered.

[0025] - each indicator is a reduction and a result of the comparison step corresponds to a non-conformity when the total instantaneous reduction is lower than the target reduction for a predefined period.

[0026] The invention also relates to a computer system suitable for implementing the preceding monitoring method.

[0027] Preferably, the monitoring system comprises, for each unit treatment process, a means for acquiring an instantaneous value of an operating parameter of the unit process considered, a means for calculating an instantaneous unit indicator from the instantaneous value and a model of the unit process considered, a means for aggregating the instantaneous unit indicators to obtain an instantaneous total indicator of the treatment, a means for comparing the instantaneous total indicator with a target indicator, and a means for generating an alert when a result at the output of the comparison means is indicative of non-compliance of the drinking water.

[0028] More preferably, the monitoring system further comprises a suitable human-machine interface, the monitoring system being configured to display, on the display screen of the human-machine interface, each instantaneous unit indicator, the instantaneous total indicator, a result of the comparison step, and / or the alert when it is generated. The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement the preceding monitoring method.

[0029] The invention and its advantages will be better understood upon reading the following detailed description of a particular embodiment, given solely as a non-limiting example, this description being made with reference to the appended drawings in which:

[0030] Figure 1 is a schematic representation of a drinking water production plant equipped with a computer monitoring system;

[0031] Figure 2 is a block representation of the monitoring method according to the invention implemented by the system of Figure 1; and,

[0032] Figure 3, [Fig 4] Figure 4 and [Fig 5] Figure 5 represent different information displayed on the screen of a human-machine interface - HMI of the system of Figure 1. GENERAL INFORMATION

[0033] A drinking water production plant implements a series of unit treatment processes.

[0034] The various unit processes ensure control of microbiological risks linked to pathogens present in raw water.

[0035] They must make a contribution to the total reduction at all times, so that the latter is sufficient in relation to the pathogen load in the raw water.

[0036] By definition, the reduction corresponds to the logarithm of the ratio between the concentration of a pathogen at the output of any process and the concentration of this same pathogen at the input of the process considered. It is a dimensionless number.

[0037] However, the reduction of a unit treatment process can vary over time.

[0038] The invention thus relates to a monitoring system based on instrumentation of the production plant, to measure in real time the operating parameters of the different unit processes and to estimate, using suitable models, the instantaneous contribution of each unit process and thus evaluate the quality of the water produced.

[0039] This monitoring system is an aid to the plant operator. It allows them to obtain a real-time assessment of the plant's ability to properly eliminate a given pathogen and to determine whether an acceptable health risk limit is being met.

[0040] This tool allows it to take into account the compensation phenomena between the unit processes that are successively implemented for the treatment of raw water by the plant. It advantageously allows the consolidation of the plant's performance indicators with regard to the elimination of pathogens, and to model the impact of modifications made to the treatment, such as the failure of a unit treatment process.

[0041] Advantageously, the monitoring system allows feedback on the unit processes by proposing operating points for each of these unit processes and advantageously by automatically regulating each unit process to reach these operating points.

[0042] STRUCTURE

[0043] Figure 1 is a schematic representation of a drinking water production plant equipped with the monitoring system according to the invention.

[0044] Plant 1 includes a treatment system 2 which implements a treatment to produce drinking water from raw water (also called a resource).

[0045] The raw water entering treatment system 2 may, for example, be rainwater collected in reservoirs, water pumped from an underground water table, wastewater to be reprocessed, etc.

[0046] The water leaving the treatment system 2 is water intended to be distributed to end consumers by a distribution network (not shown in Figure 1).

[0047] The results of one or more initial microbiological analyses made it possible to identify a list of reference pathogens affecting or likely to affect raw water.

[0048] A reference pathogen is a pathogen actually detected by microbiological analysis in raw water, or a pathogen belonging to the same family as a pathogen actually detected by microbiological analysis in raw water.

[0049] The list of reference pathogens includes, for example, intestinal parasites such as Cryptosporidium and Giardia, pathogenic bacteria such as enterohaemorrhagic strains of Escherichia coli or Campylobacter, and human viruses such as norovirus, rotavirus, and adenovirus.

[0050] Following these initial analyses, a suitable treatment process is designed and the treatment system enabling this treatment process to be carried out is deployed.

[0051] A treatment process, such as that implemented for example by treatment system 2, is subdivided into a plurality of unit processes, which are implemented by as many unit sections of plant 1.

[0052] The unit treatment sections are for example grouped in a first phase 10 of physical elimination (such as for example the elimination of sludge), followed by a second phase 20 of inactivation of pathogens (such as for example the elimination of bacteria). The first phase 10 comprises for example two sections operating in parallel with each other. Each section comprises for example a section 12 for carrying out a unit process of settling the raw water (or clarification), followed by a section 14 for carrying out a unit process of filtration of the settled water (for example carried out using granular activated carbon filters - GAC).

[0053] The second phase 20 comprises, for example, successively a section 22 for carrying out a unitary process for ozonation of the filtered water, a section 24 for carrying out a unitary process for UV disinfection of the ozonated water, and a section 26 for carrying out a unitary process for chlorination of the disinfected water. The chlorinated water obtained at the outlet of the chlorination section 26 is the water produced by the plant.

[0054] The water produced must meet a certain number of constraints in order to be considered potable, i.e. suitable for human consumption.

[0055] To ensure real-time monitoring of these constraints, factory 1 is, according to the invention, equipped with a monitoring system 3.

[0056] The monitoring system 3 comprises a plurality of sensors.

[0057] More specifically, one or more of the unit sections of Plant 1 are equipped with one or more sensors.

[0058] Each sensor delivers a raw measurement of a particular operating parameter of the corresponding unit process. The different sensors do not need to be synchronized or operate at the same sampling period.

[0059] Thus, for example, the ozonation section 22 is equipped with a sensor 221 suitable for measuring the temperature (°C) in the ozonation tank and a sensor 222 suitable for measuring the residual quantity of ozone (mg / L) in the water leaving the ozonation tank.

[0060] Thus, for example, the UV disinfection section 24 is equipped with a sensor 241 capable of measuring the UV dose per unit area (mJ / cm2) applied to the surface of the UV disinfection tank during the entire UV disinfection process.

[0061] Thus, for example, the chlorination section 26 is equipped with a sensor 261 suitable for measuring the pH (unitless) of the water in the chlorination tank, a sensor 262 suitable for measuring the level (m) of the water in the chlorination tank, and a sensor 263 suitable for measuring the discharge flow rate (expressed in m3 / h) of the water leaving the chlorination tank.

[0062] The monitoring system 3 also comprises an acquisition device 30, a communication network 35 and a database 40.

[0063] The acquisition device 30 is adapted to acquire the raw values ​​delivered by the various sensors equipping the processing system 2 of the factory 1 and to store these raw values, with their acquisition date, in the database 40, via the communication network 35. The acquisition device 30 comprises for example an acquisition electronics, which is connected to the various sensors, and a computer, which is connected to the acquisition electronics and programmed to record the raw values ​​at the output of the acquisition electronics, in the base 40. The computer is equipped with a communication card to be able to use the network 35 to communicate with the database 40.

[0064] The communication network 35 is a local or wide area network, private or public, respecting for example the ETHERNET protocol.

[0065] The monitoring system 3 comprises a microbiological analysis means 45 so as to know a current concentration of at least one reference pathogen in the raw water. Preferably, these analyses are carried out regularly, for example every week.

[0066] Preferably, the means 45 automatically performs microbiological analyses of the raw water.

[0067] Alternatively, these analyses are carried out in the laboratory.

[0068] The results of the microbiological analyses are preferably stored in the database 40. They are stored there with an acquisition date.

[0069] The monitoring system 3 comprises a control device 50, which is preferably associated with a human-machine interface HMI 60.

[0070] The control device 50 is a computer, connected to the communication network 35, in particular to be able to access the database 40 in reading and writing.

[0071] A computer has computing means, such as a processor, and storage means, such as memory. Memory stores, in particular, the instructions of various computer programs.

[0072] The control device 50 thus comprises a data preprocessing program 52.

[0073] Program 52 allows the raw values ​​measured by the various sensors of the installation and stored in the database 40 to be preprocessed.

[0074] The program 52 advantageously executes automatic measurement validation algorithms. For example, a new value from a sensor is compared to previous values ​​from this same sensor (to evaluate a dynamic evolution of the parameter measured by this sensor for example), to values ​​from other sensors (to evaluate a consistency criterion between the parameters measured by these sensors for example), and / or to parameterized thresholds (such as a maximum acceptable value threshold and / or a minimum acceptable value threshold for the measured parameter). Depending on the result of this comparison, this new value is qualified as valid and may be taken into consideration in the rest of the calculations, or as invalid and will not be taken into consideration in the rest of the calculations.

[0075] The program 52 executes a calculation algorithm making it possible to obtain the instantaneous value of an operating parameter from one or more raw values, possibly validated, of this parameter. For example, the average value of the raw values ​​measured by a sensor over a predefined time interval makes it possible to obtain an instantaneous value of the corresponding operating parameter.

[0076] For example, this average value is calculated over a 5-minute interval, with an update frequency of 5 minutes.

[0077] This interval must remain relatively short so that the average value can be considered as an instantaneous value of the corresponding operating parameter.

[0078] Indeed, the notion of real time depends on the characteristic time scale of the phenomenon being monitored. In the context of drinking water treatment, a characteristic time scale for the evolution of the concentration of a pathogen is of the order of a few hours. For example, the evolution of the concentration of a pathogen in raw water after a rainstorm occurs on a time scale of the order of half a day. For example, the duration of a unit process such as ozonation is of the order of an hour. The notion of real time then characterizes the quantities that are measured or calculated on a time scale much shorter than this characteristic time scale, i.e. between one minute and twenty minutes in the case of drinking water production. The time scale used by the control device 50 is advantageously configurable within this range of values. It is for example set at 15 minutes.

[0079] Such pre-processing also advantageously makes it possible to synchronize and give all instantaneous values ​​the same time step.

[0080] Program 52 is adapted to store the calculated instantaneous values ​​in the database 40.

[0081] The control device 50 comprises a calculation program 54.

[0082] The calculation program 54 can be subdivided into several functional modules.

[0083] A first module 541 of the calculation program 54 makes it possible to calculate a target reduction, per reference pathogen, based on the results of the microbiological analysis for the current period.

[0084] The target reduction depends on the initial concentration of the reference pathogen considered (i.e. the current results of the analysis step) and the health constraints that the water leaving plant 1 must meet in order to be qualified as drinking water, this constraint being expressed as a concentration of the pathogen considered in the drinking water. If the integer j is used to index the different reference pathogens, the current target reduction can be noted Aj.

[0085] This information is stored in database 40.

[0086] A second module 542 of the calculation program 54 makes it possible to determine an instantaneous unit reduction per unit process and per reference pathogen. If the integer i is used to index the different unit processes of plant 1 and the integer j is used to index the different reference pathogens, the instantaneous unit reduction can be noted aij(t), where t is the instant considered.

[0087] This instantaneous unit reduction is calculated from the instantaneous values ​​associated with the unit process considered and a model of this unit process. For example, this model may consist of a chart associating instantaneous unit reduction and instantaneous values ​​of the relevant operating parameters of the unit process considered.

[0088] This information is stored in database 40.

[0089] A third module 543 of the calculation program 54 makes it possible to calculate a total instantaneous reduction per pathogen, Aj(t), by aggregating the different instantaneous unit reductions aÿ(t), for the pathogen j considered. For example, the total instantaneous reduction is obtained by summing the instantaneous unit reductions of the different unit processes which follow one another in the treatment carried out by the production plant.

[0090] This information is also stored in database 40.

[0091] A fourth module 544 of the calculation program 54 is adapted to compare, at each instant t, the value of the total instantaneous reduction per pathogen, Aj(t), with the target reduction for this same pathogen, Aj.

[0092] The fifth module 545 is adapted to perform an action when the instantaneous total reduction is less than the target reduction. This action is, for example, the generation of an alert.

[0093] Preferably, the action is actually performed when the instantaneous total reduction remains below the target reduction for a predefined period, so as to avoid false alerts.

[0094] The generation of an alert corresponds to the detection of a non-conformity in the treatment actually carried out by the production plant at the current time, compared to what is required to comply with health safety constraints.

[0095] The device 50 comprises a display program 56 which is adapted to display information on a screen of the HMI 60. The latter is connected to the computer 50, either directly or indirectly, by a wired connection or a wireless connection. Preferably, the HMI 60 behaves as a client and the computer 50 as a server.

[0096] The display program 56 is adapted to extract the information to be displayed in the database 40.

[0097] The information presented on the HMI 60 should enable an operator to monitor the operation of the plant, at least on a microbiological level.

[0098] For example, the display program 56 makes it possible to display on the screen a first window (Figure 3) presenting, for a particular pathogen selected by the operator, the temporal evolution of the instantaneous unit reduction for each elementary process along the raw water treatment chain, as well as the total instantaneous reduction.

[0099] For example, the display program 56 makes it possible to display on the screen a second window (Figure 4) presenting, for a unit process selected by the operator, the temporal evolution of the instantaneous reduction of this unit process for each pathogen of all or part of the list of reference pathogens.

[0100] For example, the display program 56 makes it possible to display on the screen a third window (Figure 5) presenting, in the form of ergonomic graphics, a dashboard showing the performance of each unit process as well as the overall performance of the plant. Performance is for example defined as the ratio of the cumulative duration of the time intervals during which the water leaving a process is in compliance with expectations, over the duration of the reference period of operation of the plant (for example one year). For example, the overall performance of the plant is the percentage of compliance during the reference period.

[0101] Advantageously, the control device 50 comprises a control program 58.

[0102] Control program 58 is suitable for defining operating points for one or more unit processes.

[0103] An operating point makes it possible to reach a target value for the instantaneous reduction of the unit process considered.

[0104] In one embodiment, the operating point is proposed to the operator. It is displayed on the screen of the HMI 60. It is then up to the operator to control the corresponding sections of the plant.

[0105] Alternatively, it is the monitoring system 3 which automatically controls the factory.

[0106] More specifically, each section of the production plant is equipped with actuators.

[0107] For example, the UV disinfection section 24 is equipped with a UV lighting device 242, the brightness of which is adjusted to modify the dose applied to the water present in the disinfection tank and consequently the unit reduction obtained by this elementary process.

[0108] The control program 58 calculates, based on the defined operating point, a setpoint value for the actuator to be controlled and thus controls the corresponding unit process.

[0109] The setpoint value is transmitted from the device 50 to the recipient actuator. For example, this transmission is carried out via the communication network 35.

[0110] For example, if the instantaneous reduction of the UV disinfection process is too low, an operating point is defined which makes it possible to achieve the desired unit reduction level.

[0111] A target dose is then calculated to reach the defined operating point. This target dose is transmitted to the U lighting device, which regulates the UV lighting to the target dose to effectively increase the instantaneous reduction of the UV disinfection process.

[0112] Thus, with program 58, monitoring system 3 controls each unit process individually, according to a short feedback loop allowing variations in the efficiency of the treatment processes to be taken into account.

[0113] In particular, in the event of a failure of a unit process, another unit process located downstream of it can be controlled so as to compensate for the loss of efficiency caused by this failure, with the aim of maintaining the total instantaneous reduction above the target reduction or as close as possible to the target reduction.

[0114] This also makes it possible to control the various unit processes so that the entire plant operates optimally, i.e. to produce quality drinking water while limiting the plant's consumption of chemicals or energy.

[0115] This also allows one unit process to be offset by another. For example, if the unit chlorination process is particularly efficient, it leads to drinking water with a taste that may displease consumers. We will therefore seek to control the other unit processes in such a way as to increase their contribution to the total reduction and consequently reduce that of the chlorination process.

[0116] The instantaneous reduction of the chlorination process is reduced, for example, by increasing the flow rate of the water circulating in the chlorination tank. A set flow rate is calculated and then transmitted to the water circulation pumps in the chlorination tanks (referenced 264 and 265 in Figure 1). Alternatively, a set quantity of chlorine is calculated and transmitted to a controlled valve for injecting chlorine into the chlorination tanks (referenced 266 in Figure 1).

[0117] The instantaneous reduction of the ozonation process is reduced, for example, by increasing the flow rate of the water circulating in the ozonation tank. A set flow rate is calculated and then transmitted to the water circulation pumps in the ozonation tank (referenced 223 in Figure 1).

[0118] Advantageously, the control device 50 also executes a simulation program 59 allowing the operator to test operating scenarios of the plant: in the event of a malfunction of one of the elementary processes, are the other treatment processes capable of sufficiently reducing the concentration of a particular pathogen so that the water produced by the plant remains drinkable?

[0119] Program 59 is accessible via HMI 60.

[0120] To perform a simulation, program 59 uses the factory's unit process models to calculate simulated instantaneous reductions, by pathogen typology, from instantaneous values ​​of the operating parameters selected by the operator.

[0121] The simulation program 59 also makes it possible to consult a history of previous simulations, which are for example recorded in the database 40.

[0122] PROCESS

[0123] Referring to Figure 2, a preferred embodiment of a method for monitoring a production plant will be presented.

[0124] The monitoring method 100 of the treatment system 2 of the plant 1 is carried out by the monitoring system 3.

[0125] The method 100 comprises a step 110 consisting of carrying out a microbiological analysis of the raw water.

[0126] One or more samples of raw water are taken and then analyzed.

[0127] The aim of this analysis is to quantify the quality of raw water by determining its current content of at least one reference pathogen.

[0128] This step 1 10 is for example done automatically. Alternatively, it is done in the laboratory.

[0129] It is carried out at regular intervals, for example every week, or in the event of an event which is known to lead to a significant variation in the quality of the raw water (contamination, storm rain leading to soil leaching, release of untreated wastewater from an upstream treatment plant, etc.). The results of the raw water analysis for each reference pathogen are preferably stored in the database 40 as current results. They are stored with a date. This information can, for example, be entered by the operator, via the HMI 56.

[0130] In a step 120, the module 541 of the calculation program 54 is executed to interpret the current results of the analysis of the raw water in order to determine the reduction necessary to control the health risks of the water produced for each reference pathogen. Knowing the final content of a reference pathogen that the water produced by the plant must respect in order to be potable, a target reduction for this pathogen is calculated taking into account the current results of the microbiological analysis.

[0131] The method 100 continues with a step 130 of acquiring the raw operating measurements of each unit process.

[0132] This acquisition step is carried out by the acquisition device 30, which acquires the raw value delivered by each of the instrumentation sensors of the factory 1, dates this raw value, and stores the dated raw value in the base 40.

[0133] Eventually, the gross values ​​are consolidated.

[0134] The method 100 comprises a step 140 of preprocessing the raw values ​​of the database.

[0135] This step 140 is carried out periodically by executing the program 52. It makes it possible to calculate, for example by averaging raw values, the instantaneous value of each operating parameter of the unit processes.

[0136] The method 100 then comprises a step 150 of determining the instantaneous unit reductions, per pathogen and per unit process. For each unit process i of the water treatment chain and for each reference pathogen ], step 150 makes it possible to determine an instantaneous reduction aij(t).

[0137] Each reduction is evaluated from a model of the corresponding unit treatment process and the instantaneous values ​​of the operating parameters involved in this model. In a particularly simple embodiment, a model is an abacus defining a predefined relationship giving an instantaneous reduction value from one or more operating parameters.

[0138] The method 100 continues with a step 155 consisting of aggregating the instantaneous unit reductions of the different unit processes with respect to the same pathogen so as to calculate a total instantaneous reduction for the pathogen considered.

[0139] The method 100 comprises a display step 200.

[0140] The results of the various reduction calculations are presented graphically on the HMI 60. The method 100 then comprises a comparison step 160 consisting of verifying that the instantaneous total reduction is greater than or equal to the target reduction which was defined in step 120. To do this, the module 544 is executed.

[0141] If not, i.e. in the event of non-compliance, an action is taken in step 170.

[0142] In a particularly simple embodiment, the action consists of issuing an alert. This alert is, for example, a graphic alert displayed on the HMI 60. Alternatively, an audible signal is issued.

[0143] In another embodiment, the action consists of executing (step 175) the control program 58 in order to define an operating point for at least one unit process, in order to find a compliant overall reduction level.

[0144] This operating point is displayed as a recommendation on the HMI 60 to help the operator manage the production plant.

[0145] But, preferably, the execution of the control program 58 also makes it possible to calculate (step 180) a setpoint value of a control quantity of the unit process considered. This setpoint value is calculated from the operating point defined in step 175.

[0146] This instruction is transmitted, via the communication network 35, to the actuator adapted to modify the operating point of the unit process.

[0147] In yet another variant, it is not only a matter of controlling the actuators of such or such unit process when a non-conformity is identified at the end of step 170, but of calculating an instantaneous difference between instantaneous reduction and target reduction and of controlling such or such unit treatment process at each instant as a function of this instantaneous difference.

[0148] Preferably, the instantaneous deviation is maintained above a predefined threshold to ensure that the target reduction is always respected. This threshold corresponds to a certain safety margin to ensure that the water produced is potable at all times.

[0149] In this variant, the method according to the invention is a control / command method making it possible to close a feedback loop for automatically controlling the production plant.

[0150] VARIANTS AND ADVANTAGES

[0151] Alternatively, while the present description has been made using the concept of abatement, other instantaneous pathogen elimination performance indicators could be used instead of or in combination with abatements.

[0152] The invention takes into account the quality of raw water and the operation of the plant in real time. The health risk assessment is therefore carried out more precisely and preventively.

[0153] The invention does not require regular analysis of produced water samples.

[0154] By calculating an instantaneous performance indicator for each unit process, the contribution of each processing step to the total reduction is assessed.

[0155] It is possible to propose limits and / or alerts for key stages of processing.

[0156] Above all, this makes it possible to take into account the compensations between successive unit processes in the elimination of a particular pathogen.

[0157] The implementation of this method allows the operator to know if the water produced is potable and to control the plant in real time, process by process, to guarantee the production of potable water at all times and / or to optimize a unit process by taking into account the other unit processes. The present invention makes it possible to limit chemical treatments by controlling the plant as closely as possible.

[0158] Those skilled in the art will note that the present invention is of major interest on sites presenting multiple and varied unit processes, a significant pathogen load in the raw water, and / or a load presenting significant fluctuations.

[0159] The invention, through an automatic approach, makes it possible to simultaneously take into account the existence of a large number of pathogens, where the state of the art was limited to a few of them.

Claims

CLAIMS 1. Method, implemented by a computer system, for monitoring (100) in real time a production plant (1) of drinking water from raw water, the production plant implementing a treatment comprising at least two unit processes successive to one another, the monitoring method comprising the steps consisting of: - define (120) a target indicator relating to the effectiveness of elimination of at least one pathogen by the treatment implemented by the production plant, taking into account the results of a microbiological analysis of a concentration of the pathogen in the raw water and a health safety constraint on a concentration of the pathogen in the drinking water; and, at each moment of operation of the production plant, - acquiring (130, 140) an instantaneous value of at least one operating parameter of each unit process of the treatment, the acquisition step comprising a step (130) consisting of measuring a plurality of raw values ​​of the operating parameter of the unit process considered by means of one or more suitable sensors, and a step (140) consisting of preprocessing the plurality of measured raw values ​​to obtain the instantaneous value of the operating parameter of the unit process considered; - determining (150) an instantaneous unit indicator relating to the effectiveness of elimination of the pathogen by each unit process of the treatment from the instantaneous value of the operating parameter of the unit process considered and a model of the unit process considered; - aggregate (155) the instantaneous unit indicators determined for each unit process to obtain an instantaneous total indicator relating to the effectiveness of elimination of the pathogen by the treatment implemented by the production plant; - compare (160) in real time the instantaneous total indicator and the target indicator to detect a non-conformity; and in the event of detection of a non-conformity, - generate (170) an alert.

2. Monitoring method according to claim 1, wherein the step of preprocessing the plurality of measured raw values ​​consists of averaging the raw values ​​over a predefined time interval.

3. Monitoring method according to any one of the preceding claims, comprising an analysis step (110) during which the microbiological analysis of the raw water is carried out, the analysis step being carried out regularly, in laboratory or automatically, to update the results used in the target indicator definition step.

4. Monitoring method according to any one of the preceding claims, comprising a step of displaying (200), on a screen of a human-machine interface, each instantaneous unit indicator, the instantaneous total indicator, a result of the comparison step, and / or the alert when it is generated.

5. Monitoring method according to any one of the preceding claims, further comprising a step (175) of defining an operating point of at least one of the unit processes of the treatment from a result of the comparison step.

6. Monitoring method according to claim 5, further comprising a control step (180) consisting of calculating a setpoint value of at least one control quantity of at least one unit process of the treatment from the operating point defined for the unit process of treatment considered.

7. Monitoring method according to any one of the preceding claims, in which each indicator is a reduction and a result of the comparison step corresponds to a non-conformity when the instantaneous total reduction is less than the target reduction for a predefined duration.

8. Monitoring system (3) adapted for implementing a monitoring method according to any one of the preceding claims.

9. Monitoring system according to claim 8, comprising, for each unit treatment process, a means (30) for acquiring an instantaneous value of an operating parameter of the unit process considered, a means (542) for calculating an instantaneous unit indicator from the instantaneous value and a model of the unit process considered, a means (543) for aggregating the instantaneous unit indicators to obtain an instantaneous total indicator of the treatment, a means (544) for comparing the instantaneous total indicator with a target indicator, and a means (545) for generating an alert when a result at the output of the comparison means is indicative of non-compliance of the drinking water.

10. Monitoring system according to claim 9 further comprising a suitable human-machine interface (60), the monitoring system being configured to display, on a display screen of the human-machine interface, each instantaneous unit indicator, the instantaneous total indicator, a result of the comparison step, and / or the alert when it is generated.

11. Computer program comprising software instructions which, when executed by a computer (50), allow implementation of a monitoring method according to any one of claims 1 to 7.

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