METHOD FOR DETERMINING THE REMAINING CAPACITY OF AN ADSORBENT AND METHOD FOR TREATING A FLUID USING SAID METHOD

Abstract

The invention relates to a method for determining the remaining capacity of an adsorbent medium in a fluid treatment unit, said treatment comprising the passage of a fluid through an adsorbent medium, said method comprising at least the following steps: a) measuring the dissolved organic carbon content of the fluid and determining the empty bed contact time on the adsorbent medium, b) determining at least one target pollutant, c) determining the breakthrough curves of at least two reference pollutants, said breakthrough curves being determined for the dissolved organic carbon content and the empty bed contact time measured in step a), d) adjusting the breakthrough curves determined in step c) from the actual operating conditions of the treatment unit, e) determining the remaining capacity of the adsorbent medium from the adjusted breakthrough curves at the end of step d) for the target pollutant(s).Figure for the abstract: None.

Description

Title of the invention: METHOD FOR DETERMINING THE REMAINING CAPACITY OF AN ADSORBENT AND METHOD FOR TREATING A FLUID USING SAID METHOD TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the field of fluid treatment systems, in particular water treatment systems, implementing an adsorption step on an adsorbent medium. More particularly, the invention relates to the management and optimization of this treatment step by proposing a method for determining the remaining capacity of an adsorbent medium and a method for treating a fluid by adsorption on an adsorbent medium implementing the method for determining the remaining capacity of the adsorbent medium. STATE OF THE ART

[0002] For fluid treatment, and in particular for the production of drinking water or the treatment of effluents, it may be proposed to reduce the organic contaminants contained in raw water or an effluent using a step of adsorption of this material on an adsorbent medium.

[0003] Indeed, the increasing load of organic contaminants (natural organic matter and micropollutants of anthropogenic or natural origin) observed in resources leads drinking water producers and effluent treaters to rehabilitate their treatment systems, which have become unsuitable for quality objectives. This increasing load of organic contaminants is also imposed on the drinking water producer when designing a new treatment facility. Finally, effluent treaters, whether effluents of industrial or tertiary origin before discharge into natural environments or effluents to be made potable (wastewater) directly or indirectly (reuse of wastewater), can also benefit from treatment taking into account a higher presence of organic contaminants.Taking into account this significant pollution by organic contaminants can in particular involve the addition, from the design stage or during rehabilitation, of a refining process, in particular using activated carbon, such as in particular filtration and / or adsorption by a bed of granular activated carbon (GAC).

[0004] In this field of water treatment, consideration of the emergence of organic micropollutants of synthetic origin still needs to be improved, particularly when they are present in small quantities.

[0005] In particular, some of these emerging pollutants are poorly adsorbable, whether they are pollutants in the form of small molecules, polar molecules, or hydrophilic molecules. These include pesticide metabolites which may thus be found downstream of the adsorption stage, such as an adsorption stage with granular activated carbon. The level of these emerging pollutants at the end of the treatment process may then exceed regulatory thresholds if these pollutants are specifically regulated or in any case present a risk to be anticipated for emerging pollutants not yet regulated.

[0006] In fact, adsorbents, such as activated carbon, see their adsorption capacity decrease as they are used to adsorb pollutants.

[0007] Manufacturers implementing this type of treatment installation seek to determine the adsorption capacity of the adsorbent media in order to be able to optimize renewal or regeneration operations.

[0008] Semi-industrial pilot tests can be set up to determine the adsorption capacity of a medium. However, these semi-industrial pilot tests are very long and expensive and must be carried out on each treatment unit (one adsorbent medium, one fluid quality, one contact time). The method of the invention makes it possible to avoid these semi-industrial pilot tests.

[0009] N. Ye et al, Model development and validation. Water Research, 2018, vol 148, pp 30-40 (Upscaling fixed bed adsorption behaviors towards emerging micropollutants in treated natural waters with aging activated carbon) developed a method in which laboratory micropollutant adsorption tests are carried out with aged GAC (granular activated carbon) to integrate the effect of clogging and competition related to organic matter. However, this method is not transferable to sites other than the dedicated study site.

[0010] Document EP 3 153 475 A1 describes the application of a dose of carbon (micro-grains) according to the reduction in UV absorbance monitored online associated beforehand with a desired reduction in micropollutant, established for the activated carbon, water and the micropollutant(s). The method described in this document does not take into account the accumulation of micropollutants in the adsorbent medium over time.

[0011] There is therefore a need to propose a method for determining the remaining capacity of an absorbent medium in a fluid treatment unit, which is quick / simple to implement, which can be easily adapted in the event of a change in conditions, which is reliable, and which takes into account the treatment unit considered. Summary of the invention

[0012] The invention relates to a method for determining the remaining capacity of an adsorbent medium in a fluid treatment unit, said treatment comprising the passage of a fluid through an adsorbent medium, said method comprising at least the following steps:

[0013] a) measurement of the dissolved organic carbon content of the fluid and determination of the contact time on an empty bed on the adsorbent medium,

[0014] b) determination of at least one target pollutant,

[0015] c) determination of the breakthrough curves of at least two reference pollutants, said breakthrough curves being determined for the dissolved organic carbon content and the empty bed contact time measured in step a),

[0016] d) adjustment of the breakthrough curves determined in step c) from the actual operating conditions of the processing unit,

[0017] e) determination of the remaining capacity of the adsorbent medium from the breakthrough curves adjusted at the end of step d) for the target pollutant(s).

[0018] According to one embodiment, the adjustment step is implemented with a step chosen from: implementation of an empirical technique, implementation of a short bed adsorber test, implementation of a medium bed adsorber test, implementation of a real pilot test.

[0019] According to one embodiment, the adjustment step is implemented using a short bed adsorber test including a step of sampling at least a portion of the adsorbent media from the treatment unit.

[0020] According to one embodiment, the method of the invention is implemented periodically, it being understood that the adjustment step can possibly be implemented with different techniques for each implementation.

[0021] According to one embodiment, the method of the invention further comprises, upstream of step c), a step of preparing at least one breakthrough curve for said at least two reference pollutants, and this for at least two dissolved organic carbon contents and two empty bed contact time values.

[0022] According to one embodiment, the step of preparing at least one breakthrough curve for at least two reference pollutants is implemented by at least one technique chosen from a pilot breakthrough test, or by mini-column (RSSCT) or from a fixed bed modeling resulting from an isothermal and kinetic type adsorption test.

[0023] According to one embodiment, if the target pollutant of step b) is not present in the breakthrough curves determined in step c), then the method further comprises a step of comparing said target pollutant with said reference pollutants of the breakthrough curves. Preferably, the comparison step comprises at least one step of chromatographic analysis of the fluid to be treated, said fluid possibly being previously concentrated, in order to determine the elution times of the target pollutant and of said at least two reference pollutants of the breakthrough curves.

[0024] According to one embodiment, the method further comprises a step of determining the breakthrough curve of the target pollutant from its comparison with the breakthrough curves of the reference pollutants.

[0025] According to one embodiment, the step of measuring the dissolved organic carbon content of the fluid to be treated is implemented using a measuring unit of the treatment unit, said measuring unit preferably being chosen from a UV spectrometer, a chromatography unit, a mass spectrometry and a fluorescence spectroscope.

[0026] The invention also relates to a method for treating a fluid in a treatment unit comprising at least one adsorbent medium, said treatment method comprising:

[0027] i. the passage of the fluid through at least one adsorbent medium,

[0028] ii. the implementation of the method for determining the remaining capacity of said adsorbent medium according to the invention making it possible to determine the remaining capacity of the adsorbent medium,

[0029] iii. determining the duration before the next renewal or regeneration of at least a portion of the adsorbent medium and / or determining the quantity of adsorbent medium to be renewed or regenerated as a function of the remaining capacity of the medium determined in step ii,

[0030] iv. the renewal or regeneration of at least a portion of the adsorbent medium according to the duration and / or the quantity of adsorbent medium determined in step iii.

[0031] According to one embodiment of the treatment method according to the invention:

[0032] - the adsorbent medium is chosen from granular activated carbon, exchange resin anions, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent media is granular activated carbon, and / or

[0033] - the fluid to be treated is chosen from water, an urban effluent, an industrial effluent, preferably, the fluid to be treated is water.

[0034] The invention also relates to a fluid treatment unit for implementing the treatment method according to the invention, said treatment unit comprising:

[0035] - at least one adsorption reactor for pollutants contained in the fluid to be treated, the reactor comprising an adsorbent medium within it,

[0036] - a unit of measurement of dissolved organic carbon content,

[0037] - a control unit for determining the duration before the next renewal renewal or regeneration of at least part of the adsorbent media and / or determining the quantity of adsorbent media to be renewed or regenerated,

[0038] - control means for activating the renewal and / or the regeneration generation of at least a portion of the adsorbent media.

[0039] According to one embodiment, the treatment unit according to the invention further comprises a unit for measuring the actual reduction in pollutants of the adsorbent medium, preferably a short bed measurement unit preferably comprising beds of volume less than or equal to 100 mL.

[0040] According to one embodiment of the treatment unit according to the invention, the adsorbent medium is chosen from granular activated carbon, anion exchange resin, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent medium is granular activated carbon.

[0041] The invention makes it possible to determine the remaining capacity of an adsorbent medium, such as activated carbon, in a fluid treatment unit, by a simple, rapid method, transposable to different treatment units and reliable. BRIEF DESCRIPTION OF THE FIGURES

[0042] [fig. 1] represents several pollutant breakthrough curves, for a type of media given adsorbent, and for two COD contents and two EBCT contact times.

[0043] [fig.2] represents, for a COD content, an EBCT contact time and a type of given adsorbent media, breakthrough curves for four pollutants.

[0044] [fig.3] represents the abatement measurements by an SBA test at a given time (a volume of fluid passed) for the four pollutants in [fig.2].

[0045] [fig.4] represents the adjusted breakthrough curves following the SBA test.

[0046] [fig.5] represents the breakthrough curve of a target pollutant, depending on the situation current (past fluid volume).

[0047] [fig.6] represents an SBA test machine.

[0048] [fig.7] represents a block diagram of a determination method according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0049] The invention relates to a method for determining the remaining capacity of an adsorbent medium implemented in a fluid treatment unit, said treatment comprising the passage of a fluid through an adsorbent medium, said method comprising at least the following steps:

[0050] a) measurement of the dissolved organic carbon content of the fluid and determination of the contact time on an empty bed on the adsorbent medium,

[0051] b) determination of at least one target pollutant,

[0052] c) determination of the breakthrough curves of at least two pollutants (called “reference pollutants”), said breakthrough curves being determined for the dissolved organic carbon content and the contact time on an empty bed measured in step a),

[0053] d) adjustment of the breakthrough curves determined in step c) from the actual operating conditions of the processing unit,

[0054] e) determination of the remaining capacity of the adsorbent medium from the breakthrough curves adjusted at the end of step d) for the at least one pollutant determined in step b).

[0055] Fluid to be treated

[0056] The fluid to be treated within the framework of the invention may be water, in particular water to be made potable, but also an urban or industrial effluent (in particular leachates, which are liquid effluents from waste storage), before discharge into the natural environment or even effluents to be made potable (such as waste water which is urban effluent) directly or indirectly (reuse of waste water).

[0057] Preferably, the fluid to be treated is a liquid, such as water. According to a particularly preferred embodiment, the method of the invention is a method for treating drinking water.

[0058] The water to be treated can be described as raw water, and can for example be taken from a watercourse, in which case we will speak of surface water, or be taken using a borehole, in which case we will speak of groundwater. The water to be treated can also be an effluent of urban origin (such as wastewater, otherwise known as urban wastewater) or industrial origin.

[0059] In the context of the present invention, the term "pollutant" refers to both organic matter and micropollutants. A micropollutant can be defined as an undesirable substance detectable in the environment at very low concentration (microgram per liter or even nanogram per liter). The presence of micropollutants in water is, at least in part, due to human activity (industrial processes, agricultural practices or drug and cosmetic residues). The micropollutant is characterized as being able, at these very low concentrations, to cause effects on living organisms due to its toxicity, persistence and bioaccumulation, or due to organoleptic nuisances (taste or odor, particularly relevant when treating water to be made potable). Micropollutants are very numerous (more than 110,000 molecules are listed by European regulations) and varied.The variety of pollutants allows them to be classified according to their origin, their nature, or even according to their very different chemical properties. Thus, micropollutants can have a natural origin (such as compounds resulting from soil degradation, including geosmin or methylisoborneol or MIB, or bacterial residues), plant (such as algae metabolites including microcystins), animal, or human. Micropollutants can be classified according to their nature, such as for example polar organic compounds, abbreviated as POC (from the English expression polar organic compounds) or organometallic compounds, abbreviated as MOC (from the English expression metal organic compounds). Micropollutants can have very different chemical properties, such as detergents, metals, hydrocarbons, pesticides, cosmetics or even medicines.The proposed fluid treatment process is therefore particularly applicable to pesticide-type compounds and associated metabolites. This process is also particularly applicable to solvents. This process is also particularly applicable to pharmaceutical residues or residues. industrial activity. All of these categories of pollutants or micropollutants are thus specifically concerned by the present invention.

[0060] The treatment unit implemented within the framework of the invention comprises at least one step of adsorption of pollutants contained in the fluid to be treated. This adsorption step is carried out using an adsorbent (or adsorbent media).

[0061] Adsorbent media

[0062] The invention can be implemented on different types of adsorbent media capable of eliminating different types of pollutants.

[0063] According to one embodiment of the invention, the adsorbent media is chosen from granular activated carbon (GAC), anion exchange resin, biomaterials, molecularly imprinted polymers (MIP) and mineral materials.

[0064] Some adsorbents such as modified clays and cyclodextrin polymers have also shown their effectiveness for certain specific micropollutants such as perfluorinated compounds (PFAs).

[0065] According to a particular embodiment, the adsorbent medium is activated carbon. Activated carbon is a material consisting essentially of carbonaceous material with a porous structure. It can be produced in a known manner by pyrolysis of precursors of natural origin (wood, bark, coconut shells, coal, peat, cotton, organic materials of various origins, etc.) or of synthetic origin (polyacrylonitrile (PAN), aramid fibers, etc.) already containing a significant proportion of carbon, this pyrolysis step being followed by a chemical or physical activation step.

[0066] Activated carbon is generally effective in removing long-chain PFAS through hydrophobic interaction.

[0067] Biomaterials may also be implemented within the scope of the invention, including biochar. Biochar is a composition comprising a pyrolyzed biomass biochar, a biomass biochar produced by hydrothermal carbonization, or a combination thereof. The biomass may be selected from agricultural crop waste, forestry waste, algae, animal or human waste, industrial waste, municipal waste, anaerobic digester waste, plant materials grown for biomass production, or a combination thereof. For example, biochars made from hardwood and pine wood may be considered. Biochar from rice husks may also be considered, in powder / granular form or in fiber form as in US2019270041A1.

[0068] The biochar may be a powdered solid or granules. The biochar may also comprise a metal salt powder or granule. The metal salt may comprise iron, aluminum, calcium, magnesium, manganese, zinc, copper, or a combination thereof, and in some examples, the metal salt metal salt comprises ferrous or ferric cations, ferrate anions, or a combination thereof. In particular embodiments, the metal salt comprises ferric chloride.

[0069] According to a particularly preferred embodiment, the determination method of the invention is implemented to determine the remaining capacity of an adsorbent medium chosen from granular activated carbon (GAC), other aforementioned adsorbent media (clays, polymer, biochar, etc.). The method of the invention can be implemented with different types of GAC.

[0070] For example, the granular activated carbon (GAC) that may fall within the scope of the invention will typically have a particle size ranging from 300 to 2400 μm for at least 85 to 90% by weight of the grains. The dimensions indicated are those of the equivalent diameter of the grains for dry sieving or for wet sieving.

[0071] Fluid treatment

[0072] In the context of the invention, the treatment unit will comprise one or more adsorbent media, for example one or more activated carbon filters, in particular CAG. During operation of the treatment unit, a fluid passes through one or more adsorbent media on which the pollutants present in the fluid will be adsorbed.

[0073] The treatment unit falling within the scope of the invention may be a drinking water production unit or a municipal or industrial wastewater treatment unit, for discharge into the natural environment or reuse.

[0074] According to a preferred embodiment, the treatment unit is a drinking water production unit.

[0075] Typically, the treatment method will comprise phases called "production phases" during which the fluid circulates through the adsorbent medium and phases called "stop phases" during which the fluid does not circulate through the adsorbent medium.

[0076] The treatment unit may comprise one or more adsorbent media filters. In this case, the determination method according to the invention may be implemented for each adsorbent media filter of the treatment unit, either simultaneously or at different times.

[0077] The adsorption capacity depends on several parameters, in particular the volume of fluid to be treated, the quality of the fluid to be treated, or even the contact time between the adsorbent media and the fluid to be treated.

[0078] Thus, for the same volume of fluid treated, two adsorbent beds can have different pollutant reduction capacities, depending on the actual variations in concentrations and the nature of the pollutants actually treated by each of these adsorbent beds. Furthermore, the theoretical adsorption capacities for a bed volume treated are generally determined pollutant by pollutant, but without taking into account the competition between organic matter and micropollutants for adsorption sites or the competition between micropollutants (also referred to as the "cocktail effect"). For example, highly adsorbable micropollutants will tend to saturate the adsorption sites before less adsorbable micropollutants have been adsorbed. Thus, competition between pollutants for adsorption sites is particularly present for compounds with a low affinity for adsorption (small polar molecules) such as pesticide metabolites. Theoretical determinations of adsorption capacities as a function of the treated bed volume may therefore tend to overestimate the remaining adsorption capacities of an actual adsorbent bed.

[0079] Method for determining the invention

[0080] The method of the invention makes it possible to determine the remaining capacity of an adsorbent medium. It takes into account the real context of the treatment unit in order to avoid this overestimation and to take into account the evolution of the parameters, in particular the type of adsorbent media, the volume of fluid to be treated, the quality of the fluid to be treated, or even the contact time.

[0081] Typically, the determination method according to the invention is implemented when the treatment unit has already started to operate, and it can be implemented periodically, for example every 3 to 12 months or depending on the volume of fluid treated by an adsorbent medium.

[0082] Determining the remaining capacity of an adsorbent medium makes it possible to predict the production time of this adsorbent medium before the breakthrough of the target pollutant(s). In the context of the invention, the remaining capacity is evaluated by determining the limit VV, VV from which the breakthrough of the pollutant is detectable. The VV corresponds to the ratio between the volume of fluid passed and the volume of adsorbent media of the treatment unit.

[0083] Step a}

[0084] The method of the invention comprises a step of measuring the dissolved organic carbon (DOC) content of the fluid and determining the empty bed contact time (EBCT) on at least one adsorbent medium of the treatment unit.

[0085] Thus, at a time t:

[0086] - the volume of fluid passed and the volume of adsorbent media of the treatment unit are measured in order to know the VV (ratio between the volume of fluid passed and the volume of adsorbent media), and - the COD content of the fluid and the EBCT contact time are determined on the treatment unit.

[0087] Empty bed contact time is typically determined by measuring the flow rate incoming, then by making the ratio between the volume of adsorbent media and an average of the incoming flow rate.

[0088] These measurements will then make it possible to determine the breakthrough curves.

[0089] The measurement of COD content can be carried out continuously or semi-continuously. A semi-continuous measurement means a measurement at regular intervals, for example once a week or once a month.

[0090] Generally, the pollutant content of the fluid is also determined at this stage, along with the COD content. Pollutants include both organic matter and micropollutants.

[0091] At this stage, the measurement of the COD content and, where appropriate, of the pollutants in the fluid can be carried out by different methods, known to those skilled in the art, for example by at least one method chosen from UV spectrometry (for example at 254 nm), chromatography, mass spectrometry and fluorescence spectroscopy (also referred to as 3D fluorescence). In a particularly preferred manner, the measurement method can be a high-performance liquid chromatography method (also referred to as high-performance liquid chromatography, abbreviated as HPLC), in particular with high resolution (referred to as high-performance liquid chromatography with high resolution, abbreviated as HPLC-HR) and even more particularly coupled with mass spectrometry (corresponds to the English expression mass spectrometry, abbreviated as MS).

[0092] This step a) can be implemented by a measuring unit making it possible to determine the dissolved organic carbon content of the fluid to be treated, said measuring unit then being located upstream of the adsorbent medium, and preferably being chosen from a UV spectrometer, a chromatography unit, a mass spectrometry and a fluorescence spectroscopy device.

[0093] Step b}

[0094] The determination method of the invention also comprises a step of determining at least one target pollutant.

[0095] Generally, the target pollutant(s) will be chosen from micropollutants, preferably the most restrictive micropollutants on site. Thus, the remaining capacity of the adsorbent media will typically be determined based on this target pollutant and the prediction of its behavior.

[0096] Typically, the method of the invention comprises a step of measuring the pollutant content of the fluid to be treated, in particular of the target pollutant(s).

[0097] This measurement can be implemented continuously or semi-continuously. The measurement of the pollutant content is preferably implemented simultaneously with the measurement of the COD content (step a)).

[0098] According to one embodiment, the target pollutant is chosen from organic matter and micropollutants. Preferably, the target micropollutant is chosen from atrazine and atrazine derivatives (such as deisopropylatrazine, hydroxyatrazine, desethyl-latrazine), metolachlor, metolachlor OXA, metolachlor ES A, meta-zachlor OXA, chlortoluron, diuron, metaldehyde.

[0099] This determination method can be implemented by a control unit of the processing unit.

[0100] Step c)

[0101] The determination method of the invention comprises at least one step of determining the breakthrough curves of at least two pollutants corresponding to the dissolved organic carbon content and the contact time on an empty bed measured in step a).

[0102] Thus, for a given type of adsorbent media, depending on the COD content and the EBCT contact time, breakthrough curves are determined for at least two pollutants. Preferably, the breakthrough curves are determined for at least three pollutants, preferably for at least four pollutants. According to one embodiment, the breakthrough curves are determined for organic matter and for at least two micropollutants, preferably at least three micropollutants.

[0103] [Fig. 1] illustrates breakthrough curves for two COD contents and two EBCTs, and this for four pollutants. Of course, the treatment unit falling within the scope of the invention may comprise a database with breakthrough curves for more than 2 COD contents and more than 2 EBCTs. Each breakthrough curve represents the C / C0 ratio of a pollutant as a function of the BV (“Bed volume”, corresponding to the VV “volume volume”, for example volume of water per volume of CAG), C0 representing the concentration of pollutant in the fluid at the inlet of the adsorbent medium and C representing the concentration of pollutant in the fluid at the outlet of the adsorbent medium.

[0104] Typically, for a COD content and an EBCT contact time, at least two breakthrough curves are integrated into a database for at least two pollutants. Preferably, for a COD content and an EBCT contact time, a breakthrough curve is prepared for at least 3 pollutants, more preferably at least 4 pollutants, advantageously from 5 to 10 pollutants.

[0105] These breakthrough curves can be prepared and integrated into a database of the processing unit. They are also referred to as "abacuses" and the pollutants whose breakthrough curve is plotted are called "reference pollutants".

[0106] Typically, molecules can be classified into three categories:

[0107] - Poorly adsorbable: having rapid breakthrough (log Kow < 1), - Moderately adsorbable: having an average breakthrough (1 < log Kow < 3), - Highly adsorbable: having a long breakthrough (log Kow > 3).

[0108] According to one embodiment, the reference pollutants comprise at least two micropollutants (called "reference micropollutants"), preferably chosen from micropollutants belonging to at least two different adsorbability categories. Preferably, the charts will be drawn for at least one "low adsorbability" micropollutant and for at least one "highly adsorbable" micropollutant. This makes it possible to cover the micropollutants likely to be found on the treatment unit in order to have a more precise and more accurate determination of the remaining capacity.

[0109] The breakthrough curves of the database can be obtained by different methods, preferably according to a deterministic model: for example isothermal and kinetic adsorption, then fixed bed modeling or by pilot breakthrough test called RSSCT test (for "Rapid Small Scale Column Test"). The isothermal and kinetic adsorption model, then fixed bed modeling has the advantage of being implemented quickly, compared to other models. Typically, these models will be implemented with an adsorbent medium similar or even identical to the (new) adsorbent medium of the treatment unit and with a fluid matrix, typically a water matrix, similar to that of the treatment unit, but doped with micropollutant(s) in order to define the breakthrough of said micropollutant(s).

[0110] The model of the isotherm and adsorption kinetics can for example be that of Freundlich, Langmuir, Elovich or Temkin. This list is not exhaustive, other models can be implemented. The fixed bed modeling of the kinetics and the isotherm can be that of homogeneous surface diffusion (HSDM for "Homogenous Surface Diffusion Model" or of pore surface diffusion (PSDM for "Pore Surface Diffusion Model"). The following models can also be cited: GCMC (Monte Carlo Grand Canon), PD (Polanyi-Dubinine), MCI (molecular connectivity index), QSAR (quantitative structure-activity relationship), LDF (Linear Driving Force Model) and various mathematical or statistical models (neural networks, learning machines)

[0111] A pilot breakthrough test called RSSCT (for "Rapid Small Scale Column Test") can be implemented for the preparation of breakthrough curves. This test makes it possible to plot a real breakthrough curve, since in this test, the fluid matrix of the treatment unit continuously feeds mini-columns of crushed adsorbent media with intermittent or continuous doping of micropollutants.

[0112] The determination method according to the invention may comprise a preliminary step of preparing the breakthrough curves determined in step c) for at least two pollutants, for at least two COD (Dissolved Organic Carbon) contents and at least two EBCT contact times. The breakthrough curves may be prepared according to one of the methods described above.

[0113] According to one embodiment, the (reference) pollutants are chosen from the organic matter and micropollutants. Preferably, the reference micropollutants are chosen from atrazine and atrazine derivatives (such as deisopropylatrazine, hydroxyatrazine, desethylatrazine), metolachlor, metolachlor OXA, metolachlor ESA, metazachlor OXA, chlortoluron, diuron, metaldehyde.

[0114] In order to accelerate the adsorption phenomena, the adsorbent media is generally ground for the preparation of these breakthrough curves and the fluid can evolve during the operating time of the treatment unit, for example depending on the seasons. Consequently, these models do not always reflect the state of the media at time t and are generally optimistic since the ground media will have more adsorption sites than the unground media used in the treatment unit.

[0115] The measurement of step a) makes it possible to determine the desired breakthrough curves, corresponding to the COD content and the EBCT contact time.

[0116] [Fig.2] corresponds to the breakthrough curves for a given COD content and EBCT contact time, for a given adsorbent media. The breakthrough curves of four pollutants PI, P2, P3, and P4 are determined in this [Fig.2]. Typically, PI can represent the organic manner and P2, P3, and P4 are three different micropollutants.

[0117] According to one embodiment, in the case where the target pollutant is not part of the pollutants of the breakthrough curves determined in step c), then the determination method of the invention comprises an additional step. Thus, preferably, if the target pollutant of step b) is not present in the breakthrough curves determined in step c), then the method further comprises a step of comparing said target pollutant with said pollutants of the breakthrough curves. The comparison step makes it possible to predict the behavior of the target pollutant.

[0118] Preferably, the comparison step comprises at least one step of chromatographic analysis of the fluid to be treated, said fluid possibly being previously concentrated, in order to determine the elution times of the target pollutant and of at least two pollutants of the breakthrough curves. The chromatographic analysis step is preferably a liquid chromatography analysis coupled with mass spectrometry (HPLC-MS)

[0119] Depending on the pollutant concentration and the implementation of the chromatography, a preliminary concentration step can be implemented. As an example of a concentration step, a solid phase extraction (SPE) can be implemented upstream of the chromatography step.

[0120] Once the target pollutant is compared to the reference pollutants of the breakthrough curves, the target pollutant is “placed” on the breakthrough curves.

[0121] Indeed, the inventors discovered a link between the elution time by chromatography and the treatability on adsorbent media. Thus, the analysis by chromatography will allow the new micropollutant to be classified according to its elution order, which will be directly linked to its treatability. Thus, if the new micropollutant is eluted between two reference micropollutants, then this will mean that its breakthrough curve will be located between the breakthrough curve of said two reference micropollutants.

[0122] As an example, referring to [fig.2], if the target pollutant has an elution time between the elution time of pollutants P2 and P3, then this means that the target pollutant will have a breakthrough between that of P2 and P3 and its breakthrough curve will then be placed on the breakthrough curve between the curves of P2 and P3.

[0123] Step c) can be implemented using a database of the processing unit, said database including in particular breakthrough curves. For the implementation of this step c), the processing unit may optionally further comprise an analysis unit for comparing pollutants. Preferably, the analysis unit comprises at least one chromatography unit, preferably column chromatography. A concentration unit, for example a solid phase extraction (SPE) unit, for concentrating the pollutants may be present in the processing unit, generally upstream of the analysis unit.

[0124] Step d}

[0125] After determining the breakthrough curves of the pollutants, typically including the breakthrough curve for each target pollutant, for a COD content and an EBCT contact time, said breakthrough curves are adjusted (or recalibrated).

[0126] Indeed, these “model” curves are not always representative of the adsorbent media of the treatment unit or of the fluid to be treated (since its composition can change over time, particularly during the seasons). This adjustment step makes it possible to take into account in particular the accumulation of micropollutants in the adsorbent media over time for the determination of the limit VV.

[0127] This adjustment is implemented from the actual operating conditions of the treatment unit, in particular of the adsorbent media.

[0128] The actual operating conditions of the treatment unit may include: - the state or quality at time t of the adsorbent medium (when implementing the method for determining the remaining capacity of the adsorbent medium), including in particular the actual reduction rate of the adsorbent medium at time t (for example, the result of a short bed adsorber test known as an SBA test (for “Short Bed Adsorber”)), - the quality of the fluid at the outlet of the adsorbent medium, it being understood that it can be monitored continuously, the data being able to be collected in a database of the treatment unit, - the history of previous implementations of the method for determining the invention, in particular in the case of a previous implementation of a short bed adsorber (SBA) test for this same adsorbent media, the history being able to be stored in a database.

[0129] This adjustment can be implemented for example by a technique chosen from:

[0130] - an empirical technique, or - a short bed adsorber test called SBA test (for “Short Bed Adsorber”).

[0131] The empirical technique is based on the history of the treatment unit and all analytical data collected during operation of the treatment unit and in particular of the adsorbent media. These analytical data are typically stored in a database. The analytical data include the evolution of the micropollutant and pollutant content at the inlet and outlet of the adsorbent media, taking into account the renewal and regeneration cycles of the adsorbent media. Thus, this empirical method is particularly well suited when breakthrough curves have already been prepared for several pollutants and several COD contents and several EBCT contact times or when the treatment unit has already been running for a certain time, for example for at least 6 months or even at least 12 months.

[0132] Depending on the history of the processing unit, it will be possible to determine the adjustment to be applied from the breakthrough curves determined in step c).

[0133] The SBA test is then implemented at the chosen time t, from a sample of fluid and the adsorbent media on the treatment unit whose remaining capacity is to be determined. The sampled fluid is doped with reference pollutants from the breakthrough curves and the target micropollutant(s) on the site studied if they are not present in the breakthrough curves.

[0134] Extraction of a sample of the adsorbent media for the implementation of the SBA test is typically carried out during a shutdown phase of the fluid treatment process.

[0135] The pollutant reduction rate can be determined by the SBA test.

[0136] Generally, the reduction rate by the SBA test is determined for as many pollutants as there are reference pollutants in the breakthrough curves determined in step c).

[0137] From the measurements of the abatement rate for micropollutants, the breakthrough curves can be adjusted.

[0138] [Fig.6] illustrates an SBA test machine 60 with 8 filtration cartridges 62 filled with adsorbent from the extracted sample.

[0139] It should be noted that the determination method of the invention may be implemented several times, at regular intervals on the same adsorbent medium taken from the treatment unit, and that it will be possible to use the SBA test for a first implementation and for another implementation, another adjustment technique, such as an empirical technique.

[0140] The SBA test technique will be the preferred technique. Indeed, it has the advantage of taking into account the adsorbent media and the fluid to be treated in the treatment unit, unlike empirical techniques.

[0141] The breakthrough curves determined in step c) are adjusted (or recalibrated) in order to coincide with the pollutant reduction rates determined by the SBA test.

[0142] [fig.3] and [fig.4] illustrate this step of adjusting the breakthrough curves for PI and P2 pollutants.

[0143] [Fig.3] shows the reduction rates of the pollutants PI, P2, and P3 obtained by the SBA test at time t (corresponding to a volume of fluid passed by 40000 BV) with the dashed vertical line. For P4, C / C0 is 0%.

[0144] From these two reduction rates via the SBA test for PI and P2, the breakthrough curves of PI, P2 and P3 are adjusted in order to match the reduction rate and the breakthrough curve at time t (40000 BV in the context of the non-limiting example of this figure).

[0145] According to the embodiment of [fig.3] and [fig.4], it is the reduction rate by SBA which made it possible to determine the adjustment of the curves to be applied. This adjustment of the curves can possibly (and alternatively to the SBA test) be implemented on the basis of an empirical method based for example on the operating history of the processing unit.

[0146] This adjustment step can be implemented using a control unit of the processing unit.

[0147] Step e)

[0148] The determination method according to the invention comprises a step in which the remaining capacity of the adsorbent medium (also called limit VV) is determined from the breakthrough curves adjusted at the end of step d).

[0149] Typically, the limit VV will be determined from the breakthrough curve of the micropollutant present in the sampled fluid having the fastest breakthrough. This could be the target pollutant of step d). The limit VV will generally be determined according to the desired limit for the C / C0 ratio. Depending on the treatment unit and the sector concerned, the operator may choose a limit VV such that C / C0 is less than or equal to 70%, or even less than or equal to 60% or even less than or equal to 50%.

[0150] [Fig. 5] shows a comparison between the current situation (past bed volume) and the breakthrough curve of the target pollutant (PC). The target pollutant was determined (in accordance with step b) of the method of the invention). It was thus determined in the context of this example that PC breaks through between P3 and P4, for example, by chromatographic analysis. Therefore, from the fitted curves of P3 and P4 of [Fig. 4], the breakthrough curve of the target pollutant PC was plotted. The target pollutant From these data, the remaining capacity of the media is determined. In the case of [Fig. 5], if the operator wishes to maintain C / CO less than or equal to 50%, then the VV limit will be 65,000. Still in the case of [fig.5], if the operator wishes total or almost total elimination of the target pollutant, then the VV limit will be 60,000.

[0151] The determination method of the invention may be repeated, for example, when the measurement of the COD content of the fluid to be treated calls into question the determination of the breakthrough curves during step c). Thus, if the COD content is greater than the COD content (during the implementation of step c)) for a time greater than a given duration, then the determination method may be implemented again by determining the breakthrough curves again with the new COD content, by determining at least one target pollutant (this may be the same target pollutant or a different target pollutant than that during the previous implementation of the determination method), by adjusting the breakthrough curves preferably on the basis of an empirical method based, for example, on a previous adjustment, and then by determining the remaining capacity of the adsorbent medium from the new adjusted breakthrough curves.

[0152] [Fig. 7] illustrates an embodiment of the determination method of the invention. As illustrated in [Fig. 7], the first step of the method comprises a step of measuring the COD content 11 and a step 11' of determining at least one target pollutant. Step 12 consists of determining the breakthrough curves for the given COD content (also considering the EBCT contact time). Considering the target pollutant 11', step Q1 consists of asking whether the target pollutant is present on the breakthrough curves of step 12. According to the embodiment illustrated in this [fig.7], if the target pollutant is present on the breakthrough curves of step 12 (O), then the method continues to step 13 and if the target pollutant is not present on the breakthrough curves (N), then the method comprises a step 12' in which the target pollutant is placed on the breakthrough curves of step 12.This step 12' can for example be a chromatographic analysis allowing to compare the elution times of the pollutants already present on the breakthrough curves and the target pollutant. The inventors discovered that the elution times were linked to the treatability of the pollutants, in particular micropollutants.

[0153] Once the breakthrough curves have been determined, the method comprises a step 13 of adjusting these curves taking into account the actual operation of the treatment unit, in particular taking into account the behavior of the adsorbent medium on the treatment unit and the history of the treatment unit. Once the curves have been adjusted (or recalibrated), the remaining capacity of the adsorbent medium is determined in step 15. Knowing the remaining capacity of the adsorbent medium thus makes it possible to determine the duration before the next renewal or the next regeneration of the adsorbent medium and / or to determine the quantity of adsorbent medium to be renewed or regenerate at step 16.

[0154] The determination method according to the invention makes it possible to anticipate the renewal and / or regeneration schedule of the adsorbent filters, without waiting for a breakthrough, which would harm the quality of the treated fluid.

[0155] The determination method according to the invention also makes it possible to have an operating strategy for the treatment unit, for example on the number of filters in operation and / or on the quantity of adsorbent media to be renewed or regenerated.

[0156] The invention also relates to a method for treating a fluid comprising: i. passing the fluid through at least one adsorbent medium, ii. implementing the method for determining the remaining capacity of said adsorbent medium according to the invention making it possible to determine the remaining capacity of the adsorbent medium, iii. determining the time before the next renewal or regeneration of at least part of the adsorbent medium and / or determining the quantity of adsorbent medium to be renewed or regenerated based on the remaining capacity of the media determined in step ii, iv. the renewal or regeneration of at least a portion of the adsorbent media according to the duration and / or quantity of adsorbent media determined in step iii.

[0157] The renewal of an adsorbent media filter can be total or partial. Indeed, in a used adsorbent media filter, it is possible to incorporate new or regenerated media and to remove only part of the used media.

[0158] A new adsorbent medium will be a medium that has not yet undergone an adsorption step.

[0159] A used adsorbent medium will be a medium that has undergone at least one adsorption step.

[0160] A regenerated media or adsorbent corresponds to an adsorbent that, after cycles of use as an adsorbent, has been treated, for example thermally or chemically, to regain adsorption capacities close to those of the new adsorbent.

[0161] Even if regeneration allows the recovery of adsorption capacities, the regenerated adsorbent may however have more limited adsorption capacities than the same adsorbent in its new state. These more limited adsorption capacities after regeneration can for example be characterized by the iodine adsorbance index number, or iodine number. This iodine number is the quantity in milligrams of iodine adsorbed per gram of adsorbent and is used to quantify the adsorbent power of an adsorbent medium. The measurement of the iodine number can in particular be carried out according to the protocol standardized by the ASTM D4607 - 14 standard. For example, for a new adsorbent, the iodine number can be greater than 950 or 1000 mg / g (such as for the preferred activated carbon). Conversely, for a used adsorbent, the iodine number can be less than 400 mg / g. Regeneration of the adsorbent can then lead to the recovery of an iodine value preferably greater than 600 mg / g or more preferably greater than 700 mg / g. Regeneration can be carried out off-site, in particular by the supplier of the adsorbent, in particular, using reactivation such as heat treatment above 800°C, in the case of an adsorbent in the form of activated carbon. The iodine value obtained for such regeneration can then be greater than 800 mg / g or even greater than 850 mg / g. Regeneration can also be carried out on the site of the treatment facility by chemical treatment or heat treatment, in particular at temperatures lower than reactivation at 800°C. This on-site regeneration advantageously makes it possible to recover part of the adsorption capacities (iodine index between 600 and 800 mg / g) without necessarily requiring more restrictive off-site reactivation.

[0162] The treatment method can be implemented so as to have a constant age of the adsorbent media to ensure permanent efficiency of pollutant removal. This can be made possible by a partial renewal of the adsorbent, according to a schedule determined using the determination method of the invention. The schedule can be updated each time the determination method of the invention is implemented.

[0163] According to one embodiment of the treatment method according to the invention, the adsorbent medium is chosen from granular activated carbon, anion exchange resin, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent medium is granular activated carbon.

[0164] According to one embodiment of the treatment method according to the invention, the fluid to be treated is chosen from water, an urban effluent, an industrial effluent, preferably, the fluid to be treated is water.

[0165] The invention also relates to a fluid treatment unit for implementing the method for treating a fluid according to the invention, said treatment unit comprising: - at least one adsorption reactor for pollutants contained in the fluid to be treated, the reactor comprising within it an adsorbent medium, - a unit of measurement for determining the dissolved organic carbon content of the fluid to be treated (upstream of the adsorbent media), - a control unit for determining the duration before the next renewal or regeneration of at least part of the adsorbent medium and / or for determining the quantity of adsorbent medium to be renewed or regenerated, - control means for activating the renewal and / or regeneration of at least part of the adsorbent medium.

[0166] Preferably, the processing unit according to the invention further comprises a base of data allowing the storage of data such as breakthrough curves, dissolved organic carbon contents, and / or contact time on an empty bed of said at least one adsorption reactor.

[0167] According to one embodiment, the treatment unit further comprises a unit for measuring the actual reduction in pollutants of the adsorbent medium, preferably a short bed measurement unit (short bed adsorber) preferably comprising beds with a volume less than or equal to 100 mL, more preferably less than or equal to 50 mL, even more preferably less than or equal to 20 mL.

[0168] According to one embodiment, the adsorption reactor comprises within it an adsorbent medium chosen from granular activated carbon, anion exchange resin, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent medium is granular activated carbon.

[0169] According to one embodiment of the processing unit, the measurement unit for determining the dissolved organic carbon content is chosen from a UV spectrometer, a chromatography unit, a mass spectrometry and a fluorescence spectroscopy device.

[0170] According to one embodiment, the processing unit according to the invention further comprises an analysis unit for comparing pollutants. Preferably, the analysis unit comprises at least one chromatography unit, preferably column chromatography. A concentration unit, for example a solid phase extraction (SPE) unit, for concentrating the pollutants may be present in the processing unit, generally upstream of the analysis unit.

[0171] Generally, the measurement unit(s) and where applicable the analysis unit is / are configured to send data (for example results of COD measurements and where applicable chromatographic analysis) to the control unit and / or to the database of the processing unit.

[0172] According to one embodiment, the control unit also makes it possible to plot breakthrough curves for the pollutants, called “reference pollutants”, implemented during step c) of the determination method of the invention. By way of example, the control unit can implement an isothermal and kinetic adsorption model, then fixed bed modeling. Alternatively or in addition, the treatment unit can comprise a pilot breakthrough test device called RSSCT test (for “Rapid Small Scale Column Test”) allowing the preparation of reference pollutant breakthrough curves.

Claims

Claims

1. Method for determining the remaining capacity of an adsorbent medium in a fluid treatment unit, said treatment comprising passing a fluid through an adsorbent medium, said method comprising at least the following steps: a. measuring the dissolved organic carbon content of the fluid and determining the empty bed contact time on the adsorbent medium, b. determining at least one target pollutant, c. determining the breakthrough curves of at least two reference pollutants, said breakthrough curves being determined for the dissolved organic carbon content and the empty bed contact time measured in step a), d. adjusting the breakthrough curves determined in step c) from the actual operating conditions of the treatment unit, e. determining the remaining capacity of the adsorbent medium from the adjusted breakthrough curves at the end of step d) for the target pollutant(s).

2. The method of claim 1, wherein the adjusting step is implemented with a step selected from: implementing an empirical technique, implementing a short bed adsorber test, implementing a medium bed adsorber test, implementing an actual pilot test.

3. A method according to any one of claims 1 to 2, wherein the adjusting step is carried out using a short bed adsorber test including a step of removing at least a portion of the adsorbent media from the treatment unit.

4. Method according to any one of claims 1 to 3, implemented periodically, it being understood that the adjustment step can optionally be implemented with different techniques for each implementation.

5. Method according to one of claims 1 to 4, further comprising, upstream of step c), a step of preparing at least one breakthrough curve for said at least two reference pollutants, and this for at least minus two dissolved organic carbon contents and two empty bed contact time values.

6. Method according to claim 5, in which the step of preparing at least one breakthrough curve for at least two reference pollutants is implemented by at least one technique chosen from a pilot breakthrough test, or by mini-column (RSSCT) or from a fixed bed modeling resulting from an isothermal and kinetic type adsorption test.

7. A method according to any one of claims 1 to 6, wherein if the target pollutant of step b) is not present in the breakthrough curves determined in step c), then the method further comprises a step of comparing said target pollutant with said reference pollutants of the breakthrough curves.

8. Method according to claim 7, in which the comparison step comprises at least one step of chromatographic analysis of the fluid to be treated, said fluid possibly being previously concentrated, in order to determine the elution times of the target pollutant and of said at least two reference pollutants of the breakthrough curves.

9. A method according to claim 7 or 8, further comprising a step of determining the breakthrough curve of the target pollutant from its comparison with the breakthrough curves of the reference pollutants.

10. A method according to any one of claims 1 to 9, wherein the step of measuring the dissolved organic carbon content of the fluid to be treated is carried out using a measuring unit of the treatment unit, said measuring unit preferably being chosen from a UV spectrometer, a chromatography unit, a mass spectrometry and a fluorescence spectroscope.

11. A method of treating a fluid in a treatment unit comprising at least one adsorbent medium, said treatment method comprising: i. passing the fluid through at least one adsorbent medium, ii. implementing the method for determining the remaining capacity of said adsorbent medium according to one of claims 1 to 10 making it possible to determine the remaining capacity of the adsorbent medium, iii. determining the duration before the next renewal or regeneration of at least part of the adsorbent medium and / or determining the quantity of adsorbent media to be renewed or regenerated based on the remaining capacity of the media determined in step ii, iv. renewing or regenerating at least part of the adsorbent media according to the duration and / or quantity of adsorbent media determined in step iii.

12. Treatment method according to claim 11, wherein: - the adsorbent medium is chosen from granular activated carbon, anion exchange resin, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent medium is granular activated carbon, and / or - the fluid to be treated is chosen from water, an urban effluent, an industrial effluent, preferably the fluid to be treated is water.

13. Fluid treatment unit for implementing the method according to one of claims 11 to 12, said treatment unit comprising: - at least one reactor for adsorption of pollutants contained in the fluid to be treated, the reactor comprising within it an adsorbent medium, - a unit for measuring the dissolved organic carbon content, - a control unit for determining the duration before the next renewal or regeneration of at least part of the adsorbent medium and / or for determining the quantity of adsorbent medium to be renewed or regenerated, - control means for actuating the renewal and / or regeneration of at least part of the adsorbent medium.

14. Treatment unit according to claim 13, further comprising a unit for measuring the actual reduction in pollutants of the adsorbent media, preferably a short bed measurement unit preferably comprising beds with a volume less than or equal to 100 mL.

15. Treatment unit according to claim 13 or 14, wherein the adsorbent media is selected from granular activated carbon, anion exchange resin, biomaterials, molecularly imprinted polymers and mineral materials, preferably the adsorbent media is granular activated carbon.

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