METHOD AND SYSTEM FOR ONLINE CONTROL OF THE REMOVAL OF MICROPOLLUENTS FROM WASTEWATER FROM A TREATMENT UNIT

Abstract

The invention relates to a method and system for online monitoring of micropollutant removal from wastewater in a treatment unit. The percentage of micropollutant removal is estimated in real time from online measurements using 3D fluorescence spectroscopy of the wastewater entering and exiting the treatment unit. Figure 1 (for the abstract)

Description

Title of the invention: METHOD AND SYSTEM FOR ONLINE CONTROL OF THE ELIMINATION OF MICROPOLLUTANTS FROM WASTEWATER OF A TREATMENT UNIT FIELD OF THE INVENTION

[0001] The invention relates to the field of water treatment, and more particularly the treatment of substances present in trace amounts, also called micropollutants. The invention relates in particular to a method for online monitoring of the elimination of these micropollutants. TECHNOLOGICAL BACKGROUND

[0002] The term "micropollutant" refers to a group of chemical substances that originate at least in part from human activities and that have known or suspected harmful effects even at the low concentrations (from ng / L to qg / L) at which they are present in the environment. Among the 100,000 chemical substances referenced in Europe, some recognized as "micropollutants" are regulated and others are not. They can be grouped by chemical families, uses, effects or regulatory status, and a micropollutant can thus belong to several groups. Industrial effluents, urban discharges, agriculture and agricultural products are sources that have been identified and studied since the 1970s. More recently, sources of micropollutants linked to domestic emissions (pharmaceuticals, cosmetics, detergents, pesticides, solvents, surfactants, plasticizers, flame retardants, etc.) have been identified and are now at the heart of the problems associated with micropollutants. Thus, for several years, treated water to be made potable, but also treated water discharged into the natural environment, must meet increasingly strict regulatory requirements and the micropollutant content must be controlled so as not to exceed certain thresholds.

[0003] The technologies used to remove these micropollutants from water are typically adsorption, for example on powdered or granular activated carbon, and ozonation. The quantity of reagent (adsorbent or ozone) used and / or consumed then depends on the concentration of micropollutants in the water to be treated. Control of this quantity of reagent is then preferable in order to reduce treatment costs while ensuring the desired reduction of micropollutants.

[0004] There are thus methods for controlling and / or monitoring the reduction of micropollutants, and, ultimately, for optimizing the concentrations of reagents necessary for the elimination of these micropollutants.

[0005] Thus, document FR3009789 proposes a method for controlling the reduction of organic micropollutants in wastewater by adsorption on activated carbon in which UV (ultraviolet) absorbance measurements of the water to be treated are regularly carried out before and after treatment. These UV absorbance measurements make it possible to calculate the percentage reduction of organic micropollutants and to regulate the concentration of activated carbon injected into the water to be treated according to this calculated percentage. This method uses a correlation between the percentage reduction in absorbance (determined from the absorbances measured before and after treatment) and the reduction which is however not always robust enough to obtain the desired efficiency of micropollutant removal. It is also difficult to correlate UV absorbance measurements with the removal of a particular micropollutant.Finally, UV absorbance measurements can be disturbed by the presence of certain organic molecules, particularly present in water of non-domestic origin which is collected with wastewater, so that the quantity of reagent added is not precisely controlled.

[0006] Document EP3348995B1 describes a method for dosing ozone or activated carbon according to the needs of a wastewater treatment plant which also uses UV absorption measurements before and after treatment. This method thus suffers from the same drawbacks as the method described in the previous document.

[0007] Also known from document EP3174833A1 is a method for controlling a water treatment installation by ozonation in which measurements of sets of parameters are carried out by means of fluorescence probes or UV-visible probes at the inlet and outlet of an ozonation treatment and at the outlet of a biological filtration carried out after the ozonation treatment. These parameters make it possible to measure a first and a second concentration of micropollutants before and after the ozonation treatment, used to control the latter in order to maintain a reduction in micropollutants within a predefined interval, and a third concentration of micropollutants after the biological filtration used to increase the quantity of ozone when this third concentration is below a threshold. The parameters used are chosen from TOC (total organic carbon), COD (chemical oxygen demand) and COD (dissolved organic carbon).This document only details the measurement by visible UV.

[0008] Document JP2002166265A describes a system for controlling water treatment using fluorescence analyzers, in particular to reduce the potential for trihalomethane formation resulting from chlorine treatment. The system makes it possible, in particular, to add a quantity of activated carbon to eliminate trihalomethane precursors. For this purpose, fluorescence measurements are carried out upstream and downstream of the addition of activated carbon. The system also makes it possible to control an amount of ozone introduced into ozone treatment reactors. Fluorescence analyzers measure relative fluorescence intensities of water by calculating a fluorescence spectrum at an excitation wavelength of 345nm and by calculating an excitation spectrum corresponding to a fluorescence spectrum at 425nm. The method uses correlations between this relative fluorescence intensity and the trihalomethane formation potential, between the activated carbon injection rate and a residual rate of the relative fluorescence intensity. This document does not teach the use of fluorescence measurements to determine a micropollutant abatement rate.

[0009] Existing methods do not allow for the estimation of an average removal efficiency of each micropollutant among a group of micropollutants, even in the presence of organic molecules likely to disturb the measurement, which can improve treatment monitoring and minimize the amount of reagent to be added. In addition, the links between the fluorescence of dissolved organic matter and the removal of micropollutants are still poorly understood, making the use of fluorescence spectroscopy difficult.

[0010] It has been shown that the rate of decrease of total fluorescence (denoted TF: sum of the regionally integrated fluorescence intensities) can be correlated with the percentage of abatement of a micropollutant (Park et al, Chemospherel93(2018) 530-537). However, measuring total fluorescence intensity is time-consuming (at least 15 minutes), so it is impossible to use this measurement for real-time abatement monitoring. In addition, total fluorescence corresponds to all fluorescent dissolved organic matter, so it is difficult, if not impossible, to correlate this total fluorescence with specific fractions of dissolved organic matter that interact in solution with micropollutants and / or have oxidation and adsorption mechanisms similar to micropollutants.

[0011] Guillossou et al (Water Research 190 (2021) 116749) have also shown that correlations can be established between fluorescence spectroscopic indicators and the efficiency of micropollutant removal. These correlations are in particular more robust than the correlations obtained by measuring UV absorbance.

[0012] However, there is a need for a control method to improve the monitoring of the elimination of micropollutants. BRIEF DESCRIPTION OF THE INVENTION

[0013] The subject of the invention is a method for controlling the elimination of micropollutants in the wastewater of a treatment unit in which the micropollutants are eliminated by bringing the wastewater into contact with at least one reagent in at least one reactor. The method according to the invention comprises the following steps:

[0014] (a) determining, between an inlet of one of the reactors of the treatment unit and an outlet from the same reactor or from a reactor located downstream of the treatment unit, at least one fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated depending on the treatment unit, each indicator (Fx) corresponding to a fluorescence intensity emitted for a pair (Xx_ex; Xx_em) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em),

[0015] (b) measuring by 3D fluorescence spectroscopy wastewater entering through said input a first fluorescence intensity (Fx_in) emitted for the at least one indicator (Fx),

[0016] (c) measuring by 3D fluorescence spectroscopy wastewater exiting through said output a second fluorescence intensity (Fx_out) emitted for the at least one indicator (Fx),

[0017] (d) calculate a percentage decrease in fluorescence intensity (AFX) between said input and said output for each indicator (Fx) from the first and second fluorescence intensities previously measured (AFX= ((Fx_in- F^outj / F x_in)xl00),

[0018] (e) determining a reduction percentage (Ab%) between said input and said output of at least one micropollutant or of a set of micropollutants to be eliminated present in the wastewater from a correlation Ab%=f(AFx) previously determined for said wastewater expressing the percentage reduction of at least one micropollutant or of the set of micropollutants to be eliminated as a function of the percentage decrease in the calculated fluorescence intensity of one or more characteristic indicators (Fx),

[0019] (f) regulating the quantity of the at least one reagent injected into the treatment unit between said input and said output depending on the reduction percentage (Ab%) determined in step (e).

[0020] The invention is particularly suitable for controlling and / or monitoring the reduction of one or more micropollutants by adsorption treatment units, typically using activated carbon or other adsorbents (zeolites, polymers, clays, silicas, metal oxides, etc.) as reagents, but is also suitable for controlling and / or monitoring the reduction of one or more micropollutants by treatment units using other reagents, such as oxidation treatment units, typically using ozone or an ozone precursor as reagent, or chlorination treatment units, or even units advanced oxidation (Fenton, photo-Fenton, UV + ozone, UV + H2O2, Ozone + H2O2 processes, etc.).

[0021] The invention also relates to a system for controlling the elimination of at least one micropollutant from the wastewater of a treatment unit comprising at least one reactor, each reactor having an inlet for the wastewater to be treated and an outlet for the treated wastewater, the system comprising:

[0022] - at least one 3D fluorescence spectroscopy measuring probe, connected fluidly (i) at the inlet of one of the reactors of the treatment unit, (ii) at the outlet of the same reactor or of a reactor located downstream of the treatment unit, or (iii) at both said inlet and said outlet via a distribution member, said at least one measuring probe being capable of determining a fluorescence intensity (Fx_in) for at least one indicator (Fx),

[0023] - a system for injecting at least one reagent (13) into the treatment unit,

[0024] - a management system (14) connected to the at least one measuring probe and to the system injection, configured for:

[0025] (i) determining between said input and said output at least one indicator (Fx) of fluorescence representative of the reduction of one or more of the micropollutants to be eliminated depending on the treatment unit, each indicator (Fx) corresponding to a fluorescence intensity emitted for a pair (Xx_ex; Xx_em) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em),

[0026] (ii) calculating a percentage decrease in fluorescence intensity (AFX) between said input and said output for each indicator (Fx) from the first and second fluorescence intensities previously measured (AFX = ((Fx_in- Fx_out) / F x_in).100),

[0027] (iii) determining between said inlet and said outlet a percentage reduction (Ab %) of the at least one micropollutant or of a set of micropollutants to be eliminated present in the wastewater from a correlation Ab%=f(AFx) previously determined for said wastewater expressing the percentage reduction of the at least one micropollutant or of the set of micropollutants to be eliminated as a function of the percentage reduction in the calculated fluorescence intensity of one or more characteristic indicators (Fx),

[0028] (iv) regulating the quantity of the at least one reagent injected by the injection system into the treatment unit between said inlet and said outlet as a function of the determined reduction percentage (Ab%). DESCRIPTION OF FIGURES

[0029] The invention is now described with reference to the accompanying non-limiting drawings, in which [Fig. 1] schematically represents a control system according to one embodiment of the invention. DEFINITIONS

[0030] The term “micropollutant(s)” as used in the present description designates organic substances such as hormones, pesticides, herbicides, phthalates, residues from pharmaceutical, cosmetic, cleaning products, metals and combinations thereof. In particular, pharmaceutical products can include, among others, families of organic compounds such as analgesics, painkillers, antiepileptics, antidepressants, hormones, antibiotics, etc.

[0031] These micropollutants may in particular include substances whose elimination is required by national legislation, such as the substances mentioned in the Water Protection Ordinance (OWO) (amendment of 4 November 2015) by the Swiss Federal Council.

[0032] These micropollutants may thus include atenolol, amisulpride, amlodipine, amisulpride, azithromycin, benzotriazole, bicalutamide, buprenorphine, candesartan, capecitabine, carbamazepine, ceftazidime, ciprofloxacin, citalopram, clarithromycin, cyproterone, deferasirox, diclofenac, disulfiram, dronedarone, duloxetine, efavirenz, erythromycin, fluoxetine, fulvestrant, furosemide, hydrochlorothiazide, ibuprofen, imidacloprid, irbesartan, ketoprofen, lanthanum, methylbenzotriazole (including 4-methylbenzotriazole and 5-methylbenzotriazole), metoprolol, mycophenolsyre, naproxen, nilotinib, ofloxacin, olanzapine, paracetamol, prednisolone, propranolol, propofol, quetiapine, sulfamethoxazole, tramadol, venlafaxine, cadmium, chromium, copper, nickel, mercury, lead, zinc and combinations thereof.

[0033] In particular, these micropollutants may include amisulpride, amisulpride, azithromycin, benzotriazole, candesartan, capecitabine, carbamazepine, ciprofloxacin, citalopram, clarithromycin, diclofenac, erythromycin, hydrochlorothiazide, irbesartan, ibuprofen, imidacloprid, ketoprofen, methylbenzotriazole (including 4-methylbenzotriazole and 5-methylbenzotriazole), metoprolol, naproxen, ofloxacin, paracetamol, propranolol, sulfamethoxazole, venlafaxine, cadmium, chromium, copper, nickel, mercury, lead, zinc and their combinations.

[0034] The term "wastewater" refers to water generally polluted by human use. A distinction can be made between domestic wastewater (from households), industrial wastewater, agricultural wastewater and rainwater. Municipal or urban wastewater may be made up of one or more of these wastewaters. Generally, when we talk about industrial wastewater, we consider that it is water treated in a treatment plant installed directly on an industrial site and which does not treat domestic or rainwater wastewater. DETAILED DESCRIPTION OF THE INVENTION

[0035] Method for controlling the elimination of micropollutants

[0036] The inventors have developed a method for controlling and / or monitoring, in particular continuously, the reduction of one or more micropollutants in the wastewater from a treatment unit in which the micropollutants are eliminated by bringing the wastewater into contact with at least one reagent in at least one reactor.

[0037] The method according to the invention comprises the following steps:

[0038] (a) determining, between an inlet of one of the reactors of the treatment unit and an outlet from the same reactor or from a reactor located downstream of the treatment unit, at least one fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated depending on the treatment unit, each indicator (Fx) corresponding to a fluorescence intensity emitted for a pair (Xx_ex; Àxcm) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em),

[0039] (b) measuring by 3D fluorescence spectroscopy wastewater entering through said input a first fluorescence intensity (Fx_in) emitted for the at least one indicator (Fx),

[0040] (c) measuring by 3D fluorescence spectroscopy wastewater exiting through said output a second fluorescence intensity (F^out) emitted for the at least one indicator (Fx),

[0041] (d) calculating a percentage decrease in fluorescence intensity (AFX) between said input and said output for each indicator (Fx) from the first and second fluorescence intensities previously measured (AFX = ((Fx_in- Fx_out) / F x_in).100),

[0042] (e) determining a reduction percentage (Ab%) between said input and said output of at least one micropollutant or of a set of micropollutants to be eliminated present in the wastewater from a correlation Ab%=f(AFx) previously determined for said wastewater expressing the percentage reduction of at least one micropollutant or of the set of micropollutants to be eliminated as a function of the percentage decrease in the calculated fluorescence intensity of one or more characteristic indicators (Fx),

[0043] (f) regulating the quantity of the at least one reagent injected into the treatment unit between said input and said output depending on the reduction percentage (Ab%) determined in step (e).

[0044] Typically, the excitation wavelengths (Xx_ex) and the emission wavelengths (Xx_em) are expressed in nanometers.

[0045] The processing unit may comprise one, two or more reactors. When at least two reactors are present, they may be connected in series and / or in parallel. Steps (a) to (e) may then be implemented:

[0046] (i) at the inlet and outlet of at least one reactor of the treatment unit, in particular of each reactor, or

[0047] (ii) at the inlet of the most upstream reactor and at the outlet of the most downstream reactor, or,

[0048] (iii) both at the inlet and outlet of at least one reactor of the treatment unit, in particular of each reactor, and at the inlet of the most upstream reactor and at the outlet of the most downstream reactor.

[0049] Therefore, during step (f), the quantity of the at least one reagent injected into the treatment unit between said inlet and said outlet is regulated as a function of each of the determined reduction percentages (Ab%), namely: - in case (i) according to the reduction percentage determined for one or more reactors of the treatment unit, preferably according to the reduction percentage determined for each of the reactors of the treatment unit, - in case (ii), depending on the percentage reduction determined between the entry and exit of the treatment unit only, - in case (iii), depending on the different percentages mentioned for cases (i) and (ii).

[0050] In case (iii), it may be possible in particular to provide for regulating as a priority the quantity of reagent(s) added to one of the reactors in order to obtain the desired reduction in one or more micropollutants at the outlet of the treatment unit. This case (iii) also makes it possible to manage the quantities of reagent(s) added to several reactors in a staged manner, by injecting the reagent(s) into one reactor at a time. It is thus possible to keep the reduction percentage of the treatment unit constant despite fluctuating reduction percentages in each of the reactors of the treatment unit. This can make it possible to optimize the use of the reagent(s).

[0051] Steps (a) to (f) are advantageously repeated so as to monitor the reduction of one or more micropollutants in the wastewater. When the quality of the wastewater is constant, it may be possible to simply repeat only steps (b) to (f) using the indicators (Fx) determined during step (a), for example when the treatment unit is started up. However, it is preferable to repeat all of the steps.

[0052] All of steps (a) to (f) or (b) to (f) are advantageously repeated over time in order to monitor the reduction of micropollutants in the wastewater, for example every hour and / or at a time interval equal to or greater than a period of time corresponding to the residence time of the wastewater in the treatment unit.

[0053] A fluorescence indicator (Fx) corresponds to a fluorescence intensity emitted for a pair (Xx_ex; Xx_em) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em). Each indicator (Fx) thus corresponds to a fraction of dissolved organic matter for which fluorescence can be measured for a given pair (Xx_ex; Xx_em). Typically, a fluorescence indicator corresponds to a pair of wavelengths (Xx_ex; Xx_em) for which the emitted fluorescence intensity is high, in particular higher than for other pairs of wavelengths of the measured fluorescence spectrum. Such indicators can be identified by analyzing the fluorescence spectra using algorithms well known to those skilled in the art, for example by the PARAFAC (Parallel Factor Analysis) data analysis method.It will thus be possible to use in the present invention indicators corresponding to fluorescence intensities emitted for pairs of wavelengths (Xx_ex; Xx_em) already identified in the prior art, or to identify new indicators by analysis of 3D fluorescence spectra.

[0054] The invention may thus comprise a prior step of identifying fluorescence indicators in which fluorescence intensities are measured by 3D fluorescence spectroscopy between said inlet and said outlet for a plurality of wastewater samples and for a plurality of wavelength pairs (Xx_ex; Xx_em), the length pair(s) (Xx_ex; Xx_em) for which the measured fluorescence intensity is the highest are identified, for example by the PARAFAC method, and the intensities emitted for the identified wavelength pair(s) are described as indicators. Typically, these indicators comprise the pair for which the fluorescence intensity is maximum as well as the pairs whose intensity represents from 70 to 100% of this maximum fluorescence intensity.

[0055] In the present invention, an indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated corresponds to a fluorescence intensity emitted for a pair of wavelengths (Xx_ex; Xx_em) capable of being linked to the content of one or more micropollutants to be eliminated from the wastewater, so that a correlation can be established between the percentage reduction of this or these micropollutants and this indicator.

[0056] An indicator (Fx) representative of the reduction of one or more of the micropollutants can be identified (determined) by means of a statistical analysis of data reduction of one or more micropollutants measured for a treatment unit between said inlet and said outlet, these data being coupled with data obtained by a 3D fluorescence spectroscopic analysis of wastewater containing the micropollutants before and after treatment (between said inlet and said outlet), in other words from a statistical analysis of Fluorescence Emission-Excitation Matrices, also designated by the acronym MEEF (EEM in English).

[0057] Advantageously, the method according to the invention can comprise a prior step of constructing a database containing:

[0058] - percentage values ​​of reduction of the micropollutant(s) to be eliminated calculated from concentrations of the micropollutant(s) measured, for a plurality of samples of wastewater treated in the treatment unit between said inlet and said outlet, and

[0059] - percentage values ​​of decrease in the measured fluorescence intensities, for the same samples of wastewater treated in the same treatment unit between the same inlet and the same outlet, by 3D fluorescence spectroscopy for a plurality of wavelength pairs (Xx_ex; Xx_em).

[0060] This database may include values ​​of percentages of reduction and decrease in fluorescence intensities measured at the inlet and outlet of one or more of the reactors of the treatment unit, preferably of each of the reactors and / or at the inlet and outlet of the treatment unit.

[0061] Typically, the values ​​contained in the database may be measured values ​​for each micropollutant whose reduction is to be controlled for a treatment unit or for different treatment units and for a plurality of samples of wastewater to be treated. For each treatment unit, these values ​​may be measured for a plurality of quantities of reagent(s) used and / or for a plurality of wastewaters. These values ​​may be measured in existing industrial treatment units.

[0062] In other words, the database may also include data relating to different treatment units (treatment by adsorption or oxidation), to the quantities of reagent(s) added, to different qualities of wastewater. Wastewater of different quality having, for example, one or more of the following characteristics: different micropollutant contents, different dissolved matter contents, different pHs, different temperatures, different mineral compositions (presence of ions likely to influence the oxidation-reduction conditions, alkalinity, hardness, etc.).

[0063] Typically, when constructing the database, micropollutant concentrations can be measured using methods well known to those skilled in the art. These concentrations can, for example, be measured by liquid or gas chromatography possibly coupled with mass spectroscopy.

[0064] The reduction (Ab%) of a micropollutant is defined by the formula Ab% = [(xy) / x].100, where x and y are respectively the concentrations of the micropollutant before and after treatment.

[0065] The fluorescence intensity values ​​can be measured on the samples of wastewater to be treated entering and leaving through said inlet and said outlet of the treatment unit, by varying the excitation wavelength from 250 to 450nm and the emission wavelength from 250 to 650nm.

[0066] Two excitation / emission fluorescence matrices are thus obtained for each sample of wastewater to be treated, one for the sample entering through said inlet and the other for the same sample leaving through said outlet. Each matrix will have a number of fluorescence intensity values ​​which will depend on the step between two successive excitation or emission wavelengths. For example, the excitation wavelength can be varied from 250 to 450nm with a step of 2nm and the emission wavelength can be varied from 250 to 650nm with a step of 5nm. Of course, other step values ​​can be envisaged.

[0067] As an example, Table 1 gives the excitation and emission wavelength ranges for the main fluorescent compounds of dissolved organic matter.

[0068] [Tables 1] Compound type Excitation wavelength (nm) Emission wavelength (nm) Aromatic proteins 240-250 280-380 Humic acids 300-380 380-480 Fulvic acids 240-280 380-480 Microbial soluble products Tryptophan type 260-280 320-360 Tyrosine type 260-280 300-320

[0069] We can then extract from each matrix the fluorescence intensities measured for the different pairs (Xx_ex; Xx_em) of excitation / emission wavelengths in order to calculate the percentages of intensity decrease contained in the database.

[0070] A person skilled in the art is able to implement 3D fluorescence measurements in order to obtain the intensities of the fluorescence indicators of the incoming wastewater and exiting through said inlet and said outlet. It may possibly provide for subtracting from the values ​​of each matrix, the fluorescence intensity values ​​obtained in the same way for distilled or ultrapure water, then normalizing the values ​​of the matrix using the Raman peak of this distilled or ultrapure water in order to obtain fluorescence data in Raman units. It may also provide for correcting the fluorescence intensities with dilution factors when necessary (Lawaetz, AJ, Stedmon, CA, 2009. Fluorescence intensity calibration using the raman scatter peak of water. Appl. Spectrosc. 63, 936-940).

[0071] The database described above can be constructed from fluorescence intensities obtained by scanning a set of excitation and emission wavelengths as previously described. It is also possible to construct another database containing the same type of data but only for a list of fluorescence indicators previously determined and which can be used for determining the correlation Ab%=f(AFx) of step (e). This other database can thus correspond to a part of the database previously described.

[0072] Advantageously, the method according to the invention can comprise a prior step of determining at least one correlation Ab%=f(AFx), this step being implemented after the step of constructing a database, and comprising:

[0073] (i) determining a plurality of correlations Ab%=f(AFx) using a model mathematical from the constructed database,

[0074] (ii) classifying the plurality of correlations determined in decreasing order of precision of determination of the reduction percentage, the first correlation corresponding to an optimal correlation giving a reduction value closest to the reduction percentage values ​​measured for the at least one micropollutant to be eliminated and / or for a set of micropollutants to be eliminated.

[0075] The mathematical model of step (i) can be chosen from a simple or multiple linear regression model, a polynomial regression model, neural networks, machine learning, etc. Preferably, the same type of model can be used to determine the plurality of correlations.

[0076] A correlation may correlate the percentage reduction of a single micropollutant to a percentage reduction in intensity of a single indicator or to the percentage reductions in intensity of several indicators. A correlation may also correlate the percentage reduction of a set or all of the micropollutants of interest to the percentage reduction in intensity of a single indicator or to the percentage reductions in intensity of several indicators.

[0077] Thus, a correlation can be written:

[0078] Ab%=f(AFi), or

[0079] Ab%=f(AFi, AFj,), or even

[0080] Ab%=f(AFi5 AFj, AFk, ...),

[0081] Where:

[0082] AF;, AFj, AFk are respectively the variations of the fluorescence intensity of the indicators F;, Fj, Fk,

[0083] Ab% is the percentage reduction of a micropollutant, a set of micropollutants or all micropollutants, in particular the micropollutants of interest. In the latter two cases, the percentage reduction then corresponds to the average of the percentage reductions of the micropollutants.

[0084] The plurality of correlations being determined (established), they can be classified (ii) in decreasing order of precision of determination of the percentage of reduction for a micropollutant, a set of micropollutants or all of the micropollutants.

[0085] This can be achieved by performing a statistical analysis of the plurality of correlations, for example by means of correlation coefficients, or the like. For example, the Pearson correlation coefficient can be used for linear relationships with a single parameter, and a partial least squares regression analysis or the Bayesian information criterion for relationships (linear or not) with several parameters.

[0086] During step (a), it is then possible to determine the at least one fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated from the previously constructed database. In particular, this at least one indicator (Fx) may be determined as a function of one or more micropollutants that it is desired to eliminate.

[0087] The determination of step (a) can thus be carried out as a function of: - one or more micropollutants to be eliminated, and - the treatment unit, and / or - the quality (characteristics) of the wastewater to be treated.

[0088] In particular, during step (a), the fluorescence intensity emitted for the wavelength pair(s) (Xx_ex; Xx_em) used in at least the optimal correlation, optionally in the first n correlations, n being a non-zero integer, can be determined as a fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated. This number n of correlations retained may be chosen by the operator according to the micropollutants likely to be present punctually in the wastewater and whose fluorescence intensity is close to one or more indicators of the first correlations. The fluorescence intensity(s) can be recorded in a memory as fluorescence indicator(s) representative of the reduction of one or more of the micropollutants to be eliminated.

[0089] Advantageously, during step (e), the correlation used can be the optimal correlation, optionally a lower rank correlation.

[0090] The classification of correlations can in particular make it possible to change the correlation when a determined reduction percentage is aberrant, as described below.

[0091] It should be noted that the following can be used during step (e): - a correlation per micropollutant to be eliminated, in particular a correlation for each of the micropollutants to be eliminated, or - a correlation for a set of micropollutants to be eliminated (for example for all micropollutants).

[0092] This can make it possible to improve the regulation of the quantity of the at least one reagent.

[0093] In particular, the correlation used in step (e) can be modified during control, particularly when an aberrant value of the reduction percentage is determined.

[0094] The method according to the invention can then comprise the following additional step (e'):

[0095] (i) determine a variation between the determined reduction percentage and the current reduction percentage, in particular by means of the optimal correction, and compare this variation to a threshold value,

[0096] (ii) use the reduction percentage thus determined in step (f) if the variation is less than the threshold value,

[0097] (iii) determining another reduction percentage value if the variation is greater than the threshold value and using this other reduction percentage value in step (f), the other reduction percentage value being determined from another previously determined correlation Ab%=f(AFx).

[0098] This other correlation may correspond to a second optimal correlation giving, after the current optimal correlation, a reduction percentage value closest to the reduction percentage values ​​measured for the at least one micropollutant to be eliminated and / or for a set of micropollutants to be eliminated. In other words, this other correlation corresponds to a correlation of lower rank compared to the optimal correlation.

[0099] The current rolloff percentage is defined as the rolloff percentage determined in a previous iteration of steps (a) to (f). Similarly, a current optimal correlation is the optimal correlation used in the previous iteration of steps (a) to (f). This step (e') may be implemented after step (e) and before step (f).

[0100] The threshold value for determining whether the variation is aberrant or not can be determined by the operator by tests, for example by varying the quality of the wastewater to be treated, in particular its content of a component which is known to emit fluorescence for excitation and emission lengths close to the indicators.

[0101] The additional step (e') may be repeated with the other steps. In other words, the optimal correlation may be used by default in step (e), at each iteration of the set of steps, a lower-rank correlation being used only when an outlier is determined.

[0102] Advantageously, the method according to the invention can comprise the following additional step:

[0103] (i) measuring at a time t concentrations of at least one micropollutant in the water to be treated between said inlet and said outlet,

[0104] (ii) calculating the percentage values ​​of reduction between said inlet and said outlet of the at least one micropollutant from the measured concentrations, and

[0105] (iii) calculating the percentage decreases in fluorescence intensities from the first and second fluorescence intensities measured during steps b) and c) at the same time t,

[0106] (iv) injecting into the database the values ​​of percentage reductions and the percentage decreases in fluorescence intensities calculated at this time t.

[0107] This additional step makes it possible to enrich the database during the implementation of the control method according to the invention, thus making it possible to further improve the precision of the method over time by improving, for example, the correlations.

[0108] This additional step can be repeated at regular intervals, for example 6 times per year, although shorter or longer frequencies are possible. At least one of the steps of determining the indicator and determining at least one correlation, preferably these two steps, can then be repeated in order to update the database and the correlations.

[0109] When the treatment unit comprises two or more reactors whose quantity of reagent is regulated by the method according to the invention, steps (i) and (ii) of the prior step of determining the correlations are then implemented for each of the reactors whose quantity of reagent(s) is regulated and / or for the treatment unit. Several fluorescence indicators (Fx) representative of the reduction of one or more of the micropollutants to be eliminated can then be determined for each of the reactors whose quantity of reagent(s) is regulated and / or for the treatment unit. For each regulated reactor and / or for the treatment unit, the choice of correlations, the monitoring of aberrant reduction percentage values ​​and / or the enrichment of the database, can be carried out as previously described.

[0110] The measurement steps (b) and (c) can advantageously be carried out by means of one or more fluorescence measurement probes, in particular connected to a management system. The other steps can be carried out by means of a management system. When a single probe is used, the measurement at the inlet and at the outlet is then carried out alternately, by controlling a valve-type distribution member. This control can be carried out by the management system.

[0111] The regulation of the quantity of the at least one reagent injected into the treatment unit between said inlet and said outlet as a function of the determined reduction percentage (step f), can be carried out by means of a reagent injection system serving to inject the at least one reagent into the wastewater to be treated, for example at said inlet or at the reactor located immediately downstream of this inlet, this injection system being connected to the management system.

[0112] Advantageously, the at least one reagent being continuously injected into the treatment unit, the step (f) of regulating the method according to the invention may comprise (i) a reduction in the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value or (ii) an increase in the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is less than a predefined threshold value, or (iii) a maintenance of the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value.

[0113] The reduction or increase of the at least one reagent may be a reduction or increase by a predefined constant quantity, independent of the current quantity of reagent injected. This predefined constant quantity may be determined by the operator of the treatment unit based on his experience of the operation of the treatment unit, for example resulting from observations of the effects of increases / reductions in the quantity of reagent.

[0114] Thus, for example, when starting up the treatment unit, it will be possible to inject a quantity of the at least one reagent corresponding to an initial setpoint, then, from the second iteration of steps (b) to (e), it will be possible to determine whether the reduction percentage determined for a micropollutant or for a set of micropollutants increases, decreases or is greater than the predefined threshold value, and respectively reduce, increase or maintain (i.e. not modify), the quantity of the at least one reagent currently injected.

[0115] This embodiment may be implemented for any treatment unit inside which at least one reagent is injected continuously, and in particular for an ozone oxidation treatment unit and for an adsorption treatment unit, in particular with powdered activated carbon.

[0116] Advantageously, the at least one reagent being injected discontinuously, the step (f) of regulating the method according to the invention may comprise (i) no injection of the at least one reagent when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value or (ii) an injection of a predefined quantity of the at least one reagent when the percentage of reduction determined for a micropollutant or for a set of micropollutants is less than a predefined threshold value and the extraction of the same quantity of the at least one used reagent from the treatment unit.

[0117] The predefined quantity of the at least one reagent to be added may be determined by the operator, in particular following tests of the treatment unit or by laboratory or pilot tests, or by means of previously established models. It may correspond to a percentage of the total quantity of the at least one reagent present in the treatment unit.

[0118] This embodiment is more particularly suitable for treatment units in which a constant mass of the at least one reagent must be maintained inside the treatment unit and in which the at least one reagent is added discontinuously. This is typically the case for adsorption treatment units operating with granular or powdered activated carbon of the type comprising at least one treatment reactor and in which the at least one reagent is injected into at least one of the reactors.

[0119] The extraction of the at least one used reagent from the treatment unit can be carried out before, during or following the injection of the predefined quantity of the at least one reagent, preferably after.

[0120] In the various embodiments, the predefined threshold value may correspond to a threshold value imposed by legislation or a user, below which the reduction is considered insufficient. For each of these embodiments, the predefined threshold values ​​mentioned may or may not be identical.

[0121] Advantageously, provision may be made to record in a memory, in particular integrated into the management system, one or more of the following data: the database, the fluorescence indicators, in particular the indicators representative of the reduction of one or more of the micropollutants to be eliminated, including where appropriate the associated wavelength pair(s), the correlation(s), in particular their order of classification, the percentages of reduction in fluorescence intensities, the determined reduction percentages, the different threshold values.

[0122] The method of controlling and / or monitoring the reduction of organic micropollutants in wastewater of the invention is particularly suitable for controlling and / or monitoring the reduction of micropollutants in urban wastewater, of domestic or industrial origin, typically of domestic origin and which may contain industrial water, originating, for example, from the chemical and pharmaceutical industries.

[0123] The wastewater for which the method according to the invention controls the elimination of micropollutants may be wastewater previously decontaminated, or not, by biological treatment.

[0124] This biological treatment advantageously makes it possible to reduce the organic matter load (COD - dissolved organic carbon). Biological treatment uses a wide variety of microorganisms, including bacteria, which transform biodegradable materials into simple products such as carbon dioxide, nitrate, nitrogen and / or biomass.

[0125] The control method according to the invention provides numerous advantages. The measurement of the fluorescence intensity of several Fx indicators alternately or simultaneously by one or more fluorescence probes upstream and downstream of a treatment unit makes it possible to guarantee the monitoring and estimation of the elimination of selected micropollutants or the elimination of micropollutants alone in the presence of organic substances likely to interfere with the measurement of the fluorescence intensity of an Fx indicator.

[0126] Several simple linear regression models are available to estimate the percentage values ​​of micropollutant reduction from several Fx indicators. This allows, when the model having the best estimate of a value (for example highest R2 coefficient) of an Fx indicator is not able to give correct estimates, to guarantee them by using another model of another Fx indicator.

[0127] Fx fluorescence indicators make it possible to characterize different fractions of dissolved organic matter such as biopolymers, humic acids, fulvic acids or aromatic proteins. Monitoring the fluorescence intensity of the Fx indicators thus also provides information on the evolution of the presence of these fractions of dissolved organic matter in the wastewater before and after treatment, thus providing additional information on the impact of micropollutant treatment on the quality of the treated water.

[0128] Micropollutant removal control system

[0129] The control method of the invention can be implemented by means of a control system according to the invention, as defined in the claims.

[0130] As shown [Fig.l], this control system 10 is intended for controlling the elimination of micropollutants from a water treatment unit 1 which comprises an inlet 1a for the entry of the water to be treated, and an outlet 1b for the evacuation of the treated water. This inlet 1a is for example in fluid communication with a supply pipe 2 for the wastewater to be treated and the outlet 1b in fluid communication with the evacuation pipe 3 for the treated wastewater.

[0131] In the embodiment shown [Fig.l], the control method is implemented between the input and the output of the processing unit, the latter being able to comprise one or more reactors connected in series and / or in parallel. The control method could nevertheless be implemented for one, several or each of the reactors of the processing unit.

[0132] The control system 10 shown [Fig.l] comprises:

[0133] - a first measuring probe 11 located at the input 1a of the processing unit,

[0134] - a second measuring probe 12 located at the output 1b of the processing unit,

[0135] - a system 13 for injecting reagent into the treatment unit,

[0136] - a management system 14.

[0137] These fluorescence probes 11,12 are suitable for implementing the steps (b) and (c) of the control method according to the invention. These are 3D fluorescence spectroscopy measuring probes. Those skilled in the art will know how to choose appropriate probes capable of carrying out measurements at the wavelengths of the Fx indicators

[0138] Each of the probes 11, 12 is preferably immersed in the wastewater to be measured, before and after the treatment unit, either directly in the supply 2 and discharge 3 pipes for the wastewater from the treatment unit, as shown [Fig.l], or in a bypass channel of these pipes.

[0139] The probes measuring the fluorescence intensity before and after treatment can be connected to an interface allowing the measured intensities to be displayed.

[0140] The invention is not limited by a number of measuring probes. It will be noted that it is possible to use a single 3D fluorescence spectroscopy measuring probe fluidically connected to the inlet 1a and to the outlet 1b of the treatment unit by a valve-type fluid distribution member. The measurement of the intensities at the inlet and at the outlet is then carried out alternately. In addition, one or more probes can be used to control several reactors of the treatment unit and / or the treatment unit as a whole (measurement between the inlet and outlet of the treatment unit).

[0141] The reagent injection system 13 is used to inject the reagent(s) into the wastewater to be treated, for example at a reactor of the treatment unit. This injection system 13 may comprise one or more supply lines 130 of the treatment unit with reagent(s), in particular to one or more reactors of the unit treatment. These pipes 130 can be connected to one or more capacities 131 containing the reagent or reagents. The injection system 13 usually further comprises a means 132 for adjusting, for example a regulating valve, the quantity of reagent(s) introduced inside the treatment unit.

[0142] The management system 14 is configured, in particular programmed, for the implementation of steps (a) and (d) to (f) of the method according to the invention, as well as additional steps of determining the correlations and enriching the database. It is, for example, an automated data integration and conversion system. This management system may be the management system of the treatment unit or of an entire wastewater treatment installation comprising the treatment unit. It may also be configured to control the measuring probe(s).

[0143] The management system 14 typically comprises one or more processors, for example a microprocessor, a microcontroller or other. It also comprises output or input / output interfaces. These may be wireless communication interfaces (Bluetooth, WIFI or other) or connectors (network port, USB port, serial port, Firewire® port, SCSI port or other). These input and / or output interfaces may form communication means, optionally bidirectional, between the management system, the fluorescence probe(s) and / or the injection system.

[0144] The management system may also include storage means which may be random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), flash memory, external memory or the like. These storage means may, among other things, store received data, measured values, calculated values, the database, correlations, and one or more computer programs.

[0145] The probe(s) 11, 12 measuring the fluorescence intensity before and after treatment are thus connected to the management system 14, as is the injection system 13. The fluorescence intensities measured by the probe(s) are transmitted to the management system which calculates a variation (AFX) of the fluorescence intensity for each indicator (Fx), corresponding, in the example of [Fig.l], to the difference between the fluorescence intensity before treatment and the fluorescence intensity after treatment. The system then calculates, from this variation, the percentage reduction of micropollutants by applying the correlation Ab%=f(AFx) recorded in the system. The system finally regulates the quantity of reagent(s).

[0146] For this purpose, the management system can for example be configured, in particular programmed, to:

[0147] (i) compare the determined reduction percentage with the percentage current reduction and with a predefined threshold value,

[0148] (ii) determining a setpoint for the quantity of reagent(s) to be injected into the treatment unit consisting of (i) a reduction in the quantity of reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than the predefined threshold value or (ii) an increase in the quantity of reagent(s) injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is less than the predefined threshold value, or (iii) maintaining the quantity of reagent(s) injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than the predefined threshold value and

[0149] (iii) transmit the instruction to the injection system 13.

[0150] Alternatively, the system may for example be configured, in particular programmed, to:

[0151] (i) compare the determined reduction percentage with a threshold value,

[0152] (ii) determining a setpoint for the quantity of reagent(s) to be injected into the treatment unit consisting of (i) no injection of reagent(s) when the reduction percentage determined for a micropollutant or for a set of micropollutants is greater than the predefined threshold value or (ii) an injection of a predefined quantity of reagent(s) when the reduction percentage determined for a micropollutant or for a set of micropollutants is less than the predefined threshold value and an extraction of the same quantity of reagent(s) from the treatment unit.

[0153] The steps described above can be implemented for one or more reduction percentages determined between the inlet and the outlet of the treatment unit and / or between the inlet and the outlet of one or more of the reactors of the treatment unit and / or between the inlet and the outlet of each of the reactors of the treatment unit.

[0154] In order to enable continuous monitoring of data and to consult daily, monthly or annual histories of the processing unit, the management system may include or be connected to an interface enabling the display of the fluorescence intensities measured by the probe(s), the variation of these intensities and / or the percentage of reduction of micropollutants.

[0155] When each of the reactors of the treatment unit is monitored at the input and output by the method described, as well as the treatment unit between its input and its output, the system according to the invention makes it possible to provide the information necessary for managing the staged renewal of a set or battery of reactors (N reactors having to reach X% overall elimination). It is then possible, thanks to the invention, to maintain this X% overall elimination with fluctuating reductions among the N reactors. The capacities of the reactant(s) are then used optimally. Examples Example 1

[0156] A group of substances is selected whose elimination is to be controlled, for example the 12 substances which are part of the substances to be controlled in urban wastewater by Swiss legislation and appearing in the Water Protection Ordinance (OWa) (amendment of 4 November 2015) of the Swiss Federal Council.

[0157] A statistically representative number of tests were conducted in an adsorption treatment unit comprising four granular activated carbon (GAC) reactors connected in parallel. The reactors are fed with wastewater through a common feed line and the treated wastewater leaving each reactor is combined in a common discharge line. Two fluorescence probes are positioned here on the feed and discharge lines respectively.

[0158] The statistical analysis of these tests made it possible to determine the representative indicators of the reduction of the following 12 substances: - a first indicator Fi corresponding to the pair of wavelengths (Xx_ex = 325 nm, Xx_em = 385 nm), for which the following relationship was determined using a simple linear regression model: %MPi = ab AFi+bp (Cl) The Pearson coefficient of this linear regression is R2 = 0.90. - a second indicator F2 corresponding to the pair of wavelengths (Xx_ex = 250 nm, Xx_em = 420 nm), for which the following relationship was determined using a simple linear regression model: %MP2 = a2. AF2 + b2, (C2) The Pearson coefficient of this linear regression is R2 = 0.85.

[0159] In the relationships Cl and C2 described above:

[0160] %MPi: average reduction percentage of the 12 substances, calculated from indicator F;,

[0161] AF; : percentage decrease in fluorescence intensity of the indicator F; before and after treatment,

[0162] a; : slope of the linear regression established for the indicator E,

[0163] b; : intersection with the ordinate axis of the correlation established for the FL indicator

[0164] In this example, the indicator F; the most representative of the reduction of the 12 substances (the one whose correlation gives a reduction value closest to the percentage reduction values ​​measured for the 12 substances) is therefore the indicator Fp

[0165] A similar linear relationship was established by replacing the 3D fluorescence measurements with UV absorption measurements (254nm) under the same processing conditions. The Pearson coefficient of the obtained linear regression is R2 = 0.74.

[0166] The use of 3D fluorescence thus makes it possible to improve the estimation of the reduction for these 12 substances. Example 2

[0167] A pharmaceutical product is selected whose elimination we wish to control, here atenolol.

[0168] A statistically representative number of tests were conducted in the same processing unit as in Example 1.

[0169] The statistical analysis of these tests made it possible to determine as an indicator Fi representative of the reduction of atenolol the same pair of wavelengths (Xx_ex = 325 nm, Xx_em = 385 nm), for which the following relationship was determined by means of a simple linear regression model:

[0170] %MP / = a^. AF! + b / , (C3)

[0171] Where:

[0172] %MPi': percentage of reduction of atenolol, expressed as a percentage,

[0173] AFi: percentage decrease in fluorescence intensity of the Fi indicator before and after treatment, also expressed as a percentage,

[0174] a^: slope of the linear regression,

[0175] bf: intersection with the y-axis.

[0176] The Pearson coefficient of this linear regression is R2 = 0.88.

[0177] A similar linear relationship was established by replacing the 3D fluorescence measurements with UV absorption measurements (254nm) under the same processing conditions. The Pearson coefficient obtained is R2 = 0.59.

[0178] The use of 3D fluorescence also makes it possible to improve the control of the reduction of this product. Example 3

[0179] Wastewater is treated in the treatment unit of Example 1.

[0180] The wastewater to be treated in this example may occasionally contain high amounts of proteins likely to emit fluorescence at emission and excitation wavelengths close to the Fp indicator. Fluorescence intensities higher than usual values ​​are then measured, leading to an erroneous reduction percentage.

[0181] In this case, when the system detects an aberrant value of the reduction percentage, it determines a new value of the reduction percentage for a correlation other than the optimal correlation giving a reduction value as low as possible. close to the percentage reduction values ​​measured for the 12 substances, here by applying the relationship C2 %MP2 = a2. AF2 + b2 determined in example 1. Example 4

[0182] A statistical analysis of the tests in Example 1 made it possible to establish the following correlation using a multiple linear regression model:

[0183] %MP = AFpaj + AF2.a2 + AF3.a3 + b (C4)

[0184] Where:

[0185] %MP: average reduction percentage of the 12 substances, expressed as a percentage,

[0186] AF;: percentage decrease in fluorescence intensity of the indicator F; before and after treatment, the indicators Fi and F2 being those determined in example 1, the indicator F3 corresponding to the fluorescence intensity emitted for the pair of wavelengths (Xx_ex = 340 nm, Xx_em = 430 nm),

[0187] a; : coefficient of the parameter AF;,

[0188] b: intersection with the y-axis.

[0189] The Pearson coefficient of this relationship is R2 = 0.98, much higher than the Pearson coefficients calculated for the correlations Cl and C2 functions only of the indicators Fi or F2. Thus, the average reduction percentage of the 12 substances can be determined even more precisely from the three indicators FB F2, F3. Example 5

[0190] In this example, the abatement performance of the 12 micropollutants whose monitoring is required by Swiss legislation is monitored in the treatment unit of Example 1. Each of the reactors is equipped with a granular activated carbon injector. Fresh GAC is injected discontinuously into the unit. Typically, each reactor receives fresh GAC in turn.

[0191] The fluorescence probes positioned upstream and downstream of the processing unit measure in real time the fluorescence intensities of the Fb indicator

[0192] The system then calculates a percentage decrease AFi of the fluorescence intensity of the indicator Fi determined in example 1, then the percentage reduction using the relationship (Cl) %MPi = ab AFi + bb

[0193] If the reduction percentage thus determined is close to the threshold of 80% required by Swiss legislation, in particular if it decreases and becomes, for example, less than 81%, the system injects into the first reactor of the fresh CAG treatment unit a quantity set by the operator corresponding, for example, to 1% of the total mass of CAG in this first reactor (other quantities are, however, conceivable and will be adapted by the operator depending on the operation of the treatment unit). After a period corresponding to the residence time of the wastewater in the treatment unit, for example 15 minutes, the system determines a reduction percentage of 81% and injects a new quantity of fresh CAG into the second reactor (for example representing 1% of the total mass of CAG of the second reactor). After a period corresponding to the residence time in the treatment unit, the system again determines the reduction percentage. If it is 83%, the system does not inject fresh CAG. The system will then regularly determine the reduction percentage and will inject fresh CAG when this reduction percentage decreases again to 82%, due to the progressive saturation of the CAG.

[0194] In this type of treatment unit, the system extracts from each reactor into which fresh CAG has been injected, a quantity of CAG identical to the quantity added in order to maintain a constant mass of reactant inside each reactor.This extraction can advantageously be carried out after washing the reactor's CAG bed, in order to avoid extracting suspended matter / biomass instead of the CAG, and in fluidization. Example 6

[0195] In this example, the abatement performance of the 12 micropollutants, the monitoring of which is required by Swiss legislation, is monitored in an ozonation treatment unit typically comprising a reactor equipped with a wastewater supply pipe, a treated wastewater discharge pipe and an ozone injection pipe. Ozone is continuously injected into the reactor. The fluorescence probes positioned upstream and downstream of the treatment unit (respectively on the supply and discharge pipes) measure the fluorescence intensities of the Fi indicator in real time.

[0196] The treatment unit operates for example with an ozone injection of 0.35 gO3 / gCOD (COD: dissolved organic carbon). The system determines the reduction percentage of the unit at regular time intervals. If the reduction percentage decreases to 81%, the system will increase the amount of ozone injected by a certain value in order to avoid reaching the threshold of 80%. This value is defined by the operator of the treatment unit and can for example be 0.01 gO3 / gCOD (other values ​​are however possible and will be adapted by the operator depending on the operation of the treatment unit), so that the final amount of ozone is 0.36 gO3 / gCOD. After a period corresponding to the residence time of the wastewater in the treatment unit, for example 15 min, the system determines a reduction percentage of 82%.The amount of ozone injected is correct, the system does not modify this amount until it determines: . - a reduction percentage of 81%, in this case it will again increase the amount of ozone to reach 0.37 gO3 / gCOD, or - a reduction percentage of 83%, in this case the system reduces the amount of ozone to reach 0.35 gO3 / gCOD in order to avoid operating the unit in over-quality conditions which are not desirable.

[0197] The control of the elimination of micropollutants from wastewater from a treatment unit having a reactor into which powdered activated carbon (PAC) is continuously injected can be carried out in a similar manner.

Claims

1. Claims Method for controlling the elimination of micropollutants from wastewater in a treatment unit in which the micropollutants are eliminated by bringing the wastewater into contact with at least one reagent in at least one reactor, comprising the following steps: (a) determining, between an inlet of one of the reactors of the treatment unit and an outlet of the same reactor or of a reactor located downstream of the treatment unit, at least one fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated depending on the treatment unit, each indicator (Fx) corresponding to a fluorescence intensity emitted for a pair (Xx_ex; Xx_em) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em), (b) measuring by 3D fluorescence spectroscopy of the wastewater entering through said inlet a first fluorescence intensity (Fx _in) emitted for the at least one indicator (Fx),(c) measuring by 3D fluorescence spectroscopy of the wastewater leaving through said outlet a second fluorescence intensity (Fx _out) emitted for the at least one indicator (Fx), (d) calculating a percentage decrease in the fluorescence intensity (AFX) between said inlet and said outlet for each indicator (Fx) from the first and second fluorescence intensities previously measured (AFX= ((Fx_in- F^out)^ _in).100), (e) determining a percentage reduction (Ab%) between said inlet and said outlet of the at least one micropollutant or of a set of micropollutants to be eliminated present in the wastewater from a correlation Ab%=f(AFx) previously determined for said wastewater expressing the percentage reduction of the at least one micropollutant or of the set of micropollutants to be eliminated as a function of the percentage reduction in the calculated fluorescence intensity of one or more characteristic indicators (Fx),(f) regulating the quantity of the at least one reagent injected into the treatment unit between said inlet and said outlet as a function of the reduction percentage (Ab%) determined in step (e), the method comprising:,

2. 1) a preliminary step of building a database containing: - percentage values ​​of reduction of the micropollutant(s) to be eliminated calculated from concentrations of the micropollutant(s) measured for a plurality of samples of wastewater treated in the treatment unit between said inlet and said outlet, and - percentage values ​​of decrease in fluorescence intensities measured, for the same samples of wastewater treated in the same treatment unit between the same inlet and the same outlet, by 3D fluorescence spectroscopy for a plurality of wavelength pairs (Xx_ex; Xx_em), and 2) a preliminary step of determining at least one correlation Ab%=f(AFx), this step being implemented after the step of constructing a database, and comprising: (i) determining a plurality of correlations Ab%=f(AFx) by means of a mathematical model from said constructed database, (ii) classifying the plurality of correlations determined in decreasing order of precision of determination of the reduction percentage, the first correlation corresponding to an optimal correlation giving a reduction value closest to the reduction percentage values ​​measured for the at least one micropollutant to be eliminated and / or for a set of micropollutants to be eliminated. Control method according to claim 1, wherein the treatment unit comprises at least two reactors connected in series and / or in parallel and steps (a) to (e) are implemented: (i) at the inlet and outlet of at least one reactor of the treatment unit, or (ii) at the inlet of the most upstream reactor and at the outlet of the most downstream reactor, or, (iii) both at the inlet and outlet of at least one reactor of the treatment unit and at the inlet of the most upstream reactor and at the outlet of the most downstream reactor, and during step (f), the quantity of the at least one reagent injected into the treatment unit is regulated between said inlet and said output based on each of the determined reduction percentages (Ab%).

3. Control method according to claim 1 or claim 2, in which step (a) comprises: determining as a fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated, the fluorescence intensity emitted for the pair or pairs of wavelengths (Xx_ex; Xx_em) used in at least the optimal correlation, optionally in the first n correlations, n being a non-zero integer.

4. A control method according to any preceding claim, wherein in step (e), the correlation Ab %=f(AFx) used to determine the reduction percentage is the optimal correlation, optionally a lower rank correlation.

5. Control method according to claim 4, comprising the following additional step (e'): (i) determining a variation between the determined reduction percentage and the current reduction percentage and comparing this variation with a threshold value, (ii) using the reduction percentage thus determined in step (f) if the variation is less than the threshold value, (iii) determining another reduction percentage value if the variation is greater than the threshold value and using this other reduction percentage value in step (f), the other reduction percentage value being determined from another previously determined correlation Ab%=f(AFx).

6. Control method according to any one of claims 1 to 5, comprising the following additional step: (i) measuring at a time t concentrations of at least one micropollutant in the water to be treated between said inlet and said outlet, (ii) calculating the percentage values ​​of reduction between said inlet and said outlet of the at least one micropollutant from the measured concentrations, (iii) calculating the percentages of reduction of the fluorescence intensities from the first and second intensities of fluorescence measured during steps (b) and (c) at the same time t, and (iv) inject into the database the reduction values ​​and the percentage decreases in fluorescence intensities calculated at this time t.

7. Control method according to any one of claims 1 to 6, wherein, the at least one reagent being continuously injected into the treatment unit, the regulation step (f) comprises (i) a reduction in the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value, or (ii) an increase in the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is less than a predefined threshold value, or (iii) a maintenance of the quantity of the at least one reagent injected when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value.

8. Control method according to any one of claims 1 to 7, in which, the at least one reagent being injected discontinuously into the treatment unit, the regulation step (f) comprises (i) no injection of the at least one reagent when the percentage of reduction determined for a micropollutant or for a set of micropollutants is greater than a predefined threshold value or (ii) an injection of a predefined quantity of the at least one reagent when the percentage of reduction determined for a micropollutant or for a set of micropollutants is less than a predefined threshold value and the extraction of the same quantity of the at least one used reagent from the treatment unit.

9. Control method according to any one of claims 1 to 8, in which steps (b) and (c) are carried out by means of at least one fluorescence measuring probe connected to a management system.

10. System (10) for controlling the elimination of at least one micropollutant from the wastewater of a treatment unit (1) comprising at least one reactor, each reactor having an inlet (1a) for the wastewater to be treated and an outlet (1b) for the treated wastewater, the system comprising: - at least one 3D fluorescence spectroscopy measuring probe, fluidically connected (i) to the inlet of one of the reactors of the treatment unit, (ii) to the outlet of the same reactor or of a reactor located downstream of the treatment unit, or (iii) to both said inlet and said outlet via a distribution member, said at least one measuring probe being capable of determining a fluorescence intensity (Fx_in) for at least one indicator (Fx), - a system for injecting at least one reagent (13) into the treatment unit, - a management system (14) connected to said at least one measuring probe and to the injection system, configured to: (i) determining between said input and said output at least one fluorescence indicator (Fx) representative of the reduction of one or more of the micropollutants to be eliminated depending on the treatment unit, each indicator (Fx) corresponding to a fluorescence intensity emitted for a pair (Xx_ex; Xx_em) of an excitation wavelength (Xx_ex) and an emission wavelength (Xx_em), (ii) calculating a percentage decrease in fluorescence intensity (AFX) between said input and said output for each indicator (Fx) from the first and second fluorescence intensities previously measured (AFX= ((Fx_in- F^out)^ _in).100), (iii) determining between said inlet and said outlet a percentage reduction (Ab%) of at least one micropollutant or of a set of micropollutants to be eliminated present in the wastewater from a correlation Ab%=f(AFx) previously determined for said wastewater expressing the percentage reduction of at least one micropollutant or of the set of micropollutants to be eliminated as a function of the percentage reduction in the calculated fluorescence intensity of one or more characteristic indicators (Fx), (iv) regulating the quantity of at least one reagent injected by the injection system into the treatment unit between said inlet and said outlet according to the determined reduction percentage (Ab%), the management system (14) being further configured to: 1) build a database containing: - percentage values ​​of reduction of the micropollutant(s) to be eliminated calculated from concentrations of the micropollutant(s) measured for a plurality of samples of wastewater treated in the treatment unit between said inlet and said outlet, and - values ​​of percentage decreases in fluorescence intensities measured, for the same samples of wastewater treated in the same treatment unit between the same inlet and the same outlet, by 3D fluorescence spectroscopy for a plurality of wavelength pairs (Xx_ex; Xx_em), then 2) determine at least one correlation Ab%=f(AFx), this determination comprising: (i) determining a plurality of correlations Ab%=f(AFx) using a mathematical model from said database, and (ii) the ranking of the plurality of correlations determined in decreasing order of precision of determination of the reduction percentage, the first correlation corresponding to an optimal correlation giving a reduction value closest to the reduction percentage values ​​measured for the at least one micropollutant to be eliminated and / or for a set of micropollutants to be eliminated.

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