FR3137377A1 - SYSTEM FOR TREATING A LIQUID SOURCE COMPRISING AMMONIA AND ASSOCIATED METHOD - Google Patents

Abstract

The invention relates to a system for treating a liquid source (11) comprising ammonia, the system comprising an extraction module (12) in the form of gaseous ammonia from the ammonia included in the liquid source (11). ) and producing a discharge liquid (13), and a conversion module (14) of the ammonia extracted into dinitrogen and dihydrogen (15), the conversion module being a reactor using a non-thermal plasma coupled or not to a catalysis. The invention also relates to a method of treating a liquid source (11) comprising ammonia, the method comprising a step of extracting gaseous ammonia and a step of converting the extracted gaseous ammonia into dinitrogen and dihydrogen (15). Figure for abstract: Fig. 1

Description

SYSTEM FOR TREATING A LIQUID SOURCE COMPRISING AMMONIA AND ASSOCIATED METHOD TECHNICAL FIELD OF THE INVENTION

The present invention relates to a system for treating a liquid source comprising ammonia. More particularly, the system of the present invention comprises a module for extracting the ammonia in the liquid source in the form of gaseous ammonia and a module for converting the extracted gaseous ammonia into nitrogen and dihydrogen.

The present invention also relates to a method of treating a liquid source comprising ammonia. More particularly, the method of the present invention comprises a step of extracting the ammonia in the liquid source as gaseous ammonia and a step of converting the extracted gaseous ammonia into nitrogen and dihydrogen.

STATE OF THE ART

Wastewater management and treatment is necessary for environmental protection. The objective of wastewater treatment is to eliminate pollution, particularly particulate pollution (also referred to as suspended matter) and soluble pollution (also referred to as dissolved pollution), and in particular carbon, nitrogen and phosphorus pollution. Beyond eliminating pollution, a wastewater treatment plant can also recover this pollution by reusing it, for resource recovery or energy generation, for example. In addition, increasing urbanization and population growth are putting significant pressure on the land available for wastewater treatment plants. These must be more compact and limit the discharge of pollutants even though they must deal with larger quantities of pollution to be treated.

Ammonia is considered a pollutant because its accumulation in water bodies can cause serious ecological problems, such as accelerated eutrophication of lakes and rivers, dissolved oxygen depletion and toxicity in fish and other aquatic animals present in the water body. Generally, effluent treatment processes are based on the removal of pollutants (anaerobic and aerobic biological processes, adsorption, chemical oxidation or combustion) or on the concentration of these pollutants (flocculation, precipitation, ultrafiltration, nanofiltration, reverse osmosis and evaporation). The traditional method of removing ammonia from municipal and industrial wastewater is based on biological treatments, i.e. nitrification and denitrification. This traditional method begins with a first step, nitrification, which includes an aerobic process, i.e. requiring active aeration, in which a specialized group of aerobic chemoautotrophic bacteria transforms ammoniacal nitrogen (NH ₄ ⁺ ) into nitrate (NO ₃ ^- ). Biological nitrification can be represented as follows (Overall reaction):

[Equation 1]

This traditional method continues with a second step, denitrification, which involves an anoxic process in which a specialized group of heterotrophic bacteria (mostly facultative anaerobic) couples the oxidation of organic substrates to the reduction of nitrates to _N2O or _N2 . Biological denitrification can be represented as follows (overall reaction):

[Equation 2]

Anaerobic digestion is used to treat wastewater and sewage sludge. Systems including anaerobic digesters produce digester liquors, commonly called centrates or filtrates when separated by centrifugation or filtration (e.g. with a belt filter or filter press).

Depending on the current regulations, the total nitrogen discharge authorization limit has a significant impact on the configuration of the wastewater treatment process (high/medium/low load/prolonged aeration). The lower the limit, the longer and more extensive the nitrification step and therefore the oxygen requirements (by aeration). In addition, low total nitrogen discharge limits are difficult to achieve by biological denitrification, requiring the addition of an exogenous carbon source (carbonates, to increase alkalinity, or methanol) for post-denitrification. Low carbon requirements also require the implementation of tertiary treatment, since biological treatments are not able to treat recalcitrant organic matter.

Sludge retention time (SRT) is one of the key parameters for wastewater treatment plant design because autotrophic nitrifying bacteria grow slowly compared to heterotrophic microorganisms (as a guide, the growth rate is approximately 0.1 for autotrophic nitrifying bacteria versus 0.3 per day for heterotrophic microorganisms) and must be maintained in the system to achieve high nitrification efficiencies (resulting in better total nitrogen removal). The lower the temperature, the longer the sludge retention time required to achieve nitrification. A strict limit on the total nitrogen discharge allowance and/or low operating temperatures necessarily result in high sludge age, high hydraulic retention time and large footprint for suspended growth systems such as activated sludge basins.

Furthermore, biological ammonia removal can be easily inhibited by toxic shock, pH change, low dissolved oxygen levels or low winter temperatures. This method therefore has weaknesses or requires at least regular checks.

Therefore, the high ammonia content (typically 500-3000 mg/L) anaerobic digester liquor (digestate) returning to the plant header can be a significant challenge and burden on plant operations, leading to increased energy and chemical (methanol, bicarbonate) consumption. These drawbacks are exacerbated when advanced anaerobic digestion processes are implemented, as they increase the ammonia content of the anaerobic digestion liquor due to increased sludge concentration and/or volatile solids removal efficiencies. Typically, the anaerobic digestion plant liquor represents only a minor hydraulic flow (less than 5% of the total flow) but can contain more than 20% of the nitrogen mass load to be treated. ^Biological treatment of ammonia generally results in complete or partial oxidation (to _N2 or _NO3- / _NO2- ⁾ and does not allow the recovery of a value-added product.

If nitrogen is recovered by stripping, i.e. a desorption process to reduce the ammonia content of a wastewater stream by the use of lime or caustic, ammonia can be recovered in the form of 1) a concentrated solution of ammonium hydroxide (ValeAz process), used as a fertilizer for agricultural purposes, mining (mineral extraction), or in the treatment of flue gases and sodium nitrate used in the protection of sewerage networks, 2) sulfate or phosphate salts (by acid washing), used as a fertilizer for agricultural purposes, 3) anhydrous ammonia (Organics Group process), generally used for the production of _H2 by thermal cracking.

However, this stripping process requires a pH change in the liquor to convert _NH4 ⁺ to _NH3 . This usually requires the addition of chemicals (caustic soda), heat (typically 50 MJ/kg ammonia removed) or a combination of both. Therefore, the more diluted the effluent, the greater the chemical or heat requirement. Therefore, _NH3 stripping systems are generally suitable for wastewaters with high ammonia content (>1000 mg/L).

Ammonia in gas form can be used for cracking processes. Ammonia cracking is the process by which ammonia is decomposed into hydrogen and nitrogen over a catalyst. This step can be formulated as follows:

[Equation 3]

This resulting gas mixture is called “forming gas” in English. It is typically used in applications where hydrogen is required either as an energy source or to form downstream manufacturing processes. The reaction is endothermic, requiring 383 kJ/mol. The process is carried out at a high temperature, between 850 and 950 °C, in the presence of nickel as a catalyst. In addition to high energy consumption, existing cracking technologies use a nickel-based catalyst, which makes them expensive both from a CAPEX (investment expenditure) and OPEX (operational expenditure) perspective.

Regarding phosphorus treatment or recovery, dissolved phosphorus contained in anaerobic digester liquors, which usually return to the head of the treatment plant, can represent a significant challenge and burden for the plant operation, leading to increased chemical consumption and sludge production, since _PO4 is removed from the water treatment stream by physicochemical precipitation by adding metal salts (iron or aluminum based salts). Alternatively, the chemical can be dosed into the anaerobic digester liquors, but the resulting physicochemical sludge still needs to be treated in the sludge treatment line.

Phosphorus recovery in a valuable form can also be implemented in anaerobic digester liquors using the crystallization/precipitation of non-metallic minerals, for example in the form of struvite (mineral composed of mono-ammonium phosphate, known in English as “Magnesium Ammonium Phosphate” whose acronym is “MAP”), calcium phosphates, brushite, hydroxyapatite, etc.

For example, patent application EP 2238081 discloses a phosphorus recovery process aimed at limiting the undesirable precipitation of phosphorus in the form of struvite in the digester and/or the pipes.

Crystallization processes rely on the solubility balance of the minerals formed, which depend on temperature and/or pH. The more concentrated the solution from which phosphorus is to be recovered, the easier it is to convert a large part of it into the desired valuable mineral. Therefore, the conversion efficiency that can be achieved depends on the concentration, and the rather low initial concentration of phosphate in the anaerobic digestion liquor often limits the applicability and recovery efficiency of these crystallization processes. Therefore, such a phosphorus recovery process may not be applicable on all plants due to a _PO4 content that is sometimes too low to implement crystallization or due to conversion rates that are too low, which harm the economic balance of such a solution.

Phosphorus refers to several forms of compounds containing phosphorus, including phosphate chemical forms and compounds containing ammonia and phosphate, such as monoammonium phosphate (MAP), ammonium salts and phosphoric acid, etc.

There is therefore a need for the treatment of wastewater and particularly liquids containing ammonia and potentially phosphorus. Indeed, these elements are considered pollutants and their elimination requires treatment facilities in order to eliminate or recover and/or recycle them.

However, known installations and systems, if they allow to follow the regulations concerning the limits of pollutant discharges, must be improved in order to reduce these discharges and potentially, to revalue, reuse these discharges in a beneficial manner.

The present invention aims to overcome all or part of the problems mentioned above by proposing a system that uses in an optimized manner the ammonia concentration and optionally the phosphorus concentration of a liquid source. The system of the present invention makes it possible in particular to directly recover the ammonia and/or phosphorus contained in a liquid source instead of eliminating them, these being previously considered mainly as pollutants. The system of the present invention doubly recovers these elements by their recovery, potentially their separation, and by their reuse.

For this purpose, the invention relates to a system for treating a liquid source comprising ammonia, the system comprising a module for extracting the ammonia contained in the liquid source in the form of gaseous ammonia and producing a discharge liquid, and a module for converting the extracted ammonia into nitrogen and dihydrogen, the conversion module being a reactor using a non-thermal plasma coupled or not to catalysis.

Advantageously, the system further comprises a module for concentrating ammonia in the liquid source which provides a concentrated liquid source of ammonia to the extraction module.

Advantageously, the concentration module of one of the systems previously described comprises at least one filtration module by ultrafiltration, by nanofiltration, by direct osmosis, by reverse osmosis, or by electrodialysis.

Advantageously, the stripping module of one of the systems previously described is configured to operate under vacuum.

Advantageously, the liquid source comprising ammonia of one of the previously described systems is fermented urine.

Advantageously, one of the systems previously described further comprises a module for purifying and/or separating the nitrogen and dihydrogen extracted by the conversion module.

Advantageously, one of the systems previously described further comprises a means for reinjecting the nitrogen and dihydrogen produced by the means for converting the extracted ammonia, or a means for reinjecting the purified dihydrogen and/or separated from the nitrogen, into a methanation reactor.

Advantageously, one of the systems previously described further comprises, upstream of the concentration module, an anaerobic digester supplying at least one anaerobic digestate liquor to a liquid/solid separation module and/or a dehydration module, the liquid/solid separation module and/or the dehydration module supplying a liquid fraction being the liquid source comprising ammonia.

Advantageously, the system further comprises a means for reinjecting the nitrogen and dihydrogen produced by the means for converting the extracted ammonia, or a means for reinjecting the purified dihydrogen and/or separated from the nitrogen, into the anaerobic digester.

Advantageously, the liquid source further comprises phosphorus and the system further comprises a first module for recovering phosphorus included in the liquid source or the concentrated liquid source, the module for concentrating ammonia in the liquid source also being a module for concentrating phosphorus present in the liquid source.

Advantageously, the liquid source further comprises phosphorus and the system further comprises a second module for recovering phosphorus included in the discharge liquid, the extraction module being configured to maintain a residual concentration of ammonia in the discharge liquid.

Advantageously, the extraction module is a stripping module, and the first or second phosphorus recovery module and the stripping module are included in a single reactor.

The invention also relates to a method for treating a liquid source comprising ammonia, the method comprising the following steps: a step of extracting gaseous ammonia from the ammonia included in the liquid source and producing a discharge liquid, and a step of converting the extracted gaseous ammonia into nitrogen and dihydrogen, the conversion step being carried out with a reactor using a non-thermal plasma coupled or not to catalysis.

Advantageously, the liquid source further comprises phosphorus, and the method further comprises a step of recovering the phosphorus in the liquid source, and/or in the liquid source after a step of concentrating the phosphorus in the liquid source, and/or in the discharge liquid.

Advantageously, the method further comprises a step of reinjecting the extracted dihydrogen and dinitrogen, or dihydrogen alone after purification or separation of the dinitrogen, into an anaerobic digester or into a methanation reactor.

Advantageously, the method further comprises a preliminary step of concentrating the ammonia included in the liquid source before the step of extracting the gaseous ammonia from the ammonia included in the liquid source.

FIGURES

Other characteristics, details and advantages of the invention will emerge from reading the description given with reference to the appended drawings given as examples and which represent:

There represents a system for treating a liquid source comprising ammonia according to the present invention and an option of this system.

There represents a system for treating a liquid source comprising ammonia, and optionally phosphorus, according to the present invention and further comprising one or more additional elements among: one or more phosphorus recovery modules, a dihydrogen and dinitrogen separation module, and a methanation reactor.

There represents a system for treating a liquid source as described in , further comprising optional reinjection means towards an anaerobic digester and a liquid/solid separation module.

DETAILED DESCRIPTION OF THE INVENTION

There represents a treatment system 10 of a liquid source 11 comprising ammonia according to the present invention and an option of this system.

The system of the present invention comprises an extraction module 12 in the form of gaseous ammonia from the ammonia included in the liquid source 11. The extraction module 12 receives as input the liquid source 11 comprising ammonia and makes it possible to separate the liquid ammonia in the form of an ammonia gas from the liquid source, transforming the liquid source into a discharge liquid 13, this discharge liquid necessarily containing an ammonia concentration lower than the ammonia concentration of the liquid source 11.

The extraction module 12 allows the transfer of ammonia into the gas phase and to recover this gas phase. In one embodiment of the invention, which can be combined with any of the embodiments of this description, the extraction module can be a stripping module, also called “strippers”, or stripping columns. In particular, stripping systems are described in patent FR2988304 B1. Such a stripping module makes it possible in particular to cause the ammonia to volatilize by means of a stream of vapor, gas or air passing through the liquid in countercurrent. The stripping module in the system of the present invention can be a physicochemical or membrane stripping module.

Membrane stripping involves two treatment steps, the first step consisting of a pretreatment of the liquor obtained from the anaerobic digester, this liquor having preferentially undergone a liquid/solid separation step, during which the equilibrium of the liquid phase is shifted towards the gas phase typically by raising the pH to between 9.3 and 10 and by increasing the temperature of the liquid source, typically between 35 and 50°C. Further pH changes may be necessary. The pretreatment potentially removes suspended solids and by-products contained in the liquors and by-products resulting from the temperature and pH increase. The ammonia then diffuses through a hydrophobic membrane or membrane contactor, with the possibility of circulating an acid solution on the other side of the membrane contactor (TMCS: trans-membrane chemisorption) to improve the transfer. In the case of a TMCS, the acid liquor concentrated in NH ₄ ⁺ can then be subjected to a pH increase to move the ammonia in the dissolved phase (NH ₄ ⁺ ) to the ammonia gas phase (NH ₃ ).

Advantageously, the stripping module is a vacuum stripping module. In particular, vacuum stripping requires a single pH change step to achieve the extraction of ammonia in gaseous form and optionally allows the use of nitrogen as a vector. A vacuum stripping module allows the removal of the necessary amount of stripping air.

The ammonia in gaseous form extracted by the extraction module 12 is then transferred to a conversion module allowing the transformation of the extracted gaseous ammonia into nitrogen and dihydrogen 15. In particular, in the system of the present invention, the conversion module is a reactor using a non-thermal plasma coupled or not to a catalysis. Preferably, the reactor using a non-thermal plasma coupled to a catalysis is a dielectric barrier plasma discharge reactor, also called a “DBD reactor”.

In a reactor using a non-thermal plasma (also called cold plasma or nonequilibrium plasma), most of the coupled energy is delivered mainly to the free electrons which are several orders of magnitude higher than the temperature of the heavy plasma species (ions and neutral molecules). Such mixtures will have high-energy electrons in a relatively cold mass of ions and neutral molecules; therefore, the apparent temperature of the gas remains similar to room temperature if exothermic or endothermic phenomena are absent. This type of plasma refers to a plasma state that is not in thermal equilibrium: equilibrium is not reached because the electron density is not high enough relative to the other heavy particles to achieve sufficient energy transfer between the electrons and the heavy particles. Ionization and chemical processes in these plasmas are established by the temperature (or energy level) of the electrons and are not so sensitive to thermal processes and gas temperature. The most common method of plasma generation is to apply an electric field to a neutral gas. If the applied field exceeds a certain energy density threshold (called the breakdown voltage), a gas discharge is formed, initiating the formation of a plasma.

Chemical processes in non-thermal plasmas are based on non-thermal activation of particles by high-energy electron collisions (also called electron impact). These electron-particle collisions will produce different initiating reaction mechanisms such as ionization, dissociation, excitation and fixation of electrons. This leads to the formation of a multitude of activated particles, radicals or ions that interact with each other or with other more stable particles before recombining and producing new molecules that can be not only gases but also liquids, solids or polymers.

A DBD, or plasma DBD, reactor involves a specific type of alternating current (AC) discharge at atmospheric pressure, providing a non-equilibrium, non-thermal, cold plasma. The main advantages of the DBD plasma reactor are its ability to produce a highly reactive plasma at room temperature with low electrical energy consumption and a short response time. An ammonia gas can then be transformed into hydrogen and nitrogen (dihydrogen and dinitrogen) in a DBD plasma reactor with high efficiencies. As examples for the use of non-thermal plasma and more specifically the DBD plasma reactor: M. El-Shafie has proven that a ''PPR'' (Plasma Plate Reactor) reactor can be used for this purpose (M. El-Shafie et al, (2020), Hydrogen Production and Heat Transfer Distributions of Ammonia Decomposition in an Atmospheric Pressure Plasma Plate Reactor, Journal of Sustainable Development of Energy Water and Environment Systems). Ammonia gas was introduced between two parallel plate electrodes. Quartz glass was used as a dielectric element with a thickness of 2 mm. A sinusoidal high voltage (12-18 kV at 10 kHz) was applied between the two electrodes. The hydrogen yield reached 83% when the distance between the electrodes was 4.5 mm. The same author studied the use of plasma-coupled catalysis to improve the efficiency of hydrogen production. Zeolite, lithium or ruthenium-based catalysts were used to convert NH ₃ to H ₂ with a rate higher than 99% (M. El-Shafie et al, Development of zeolite-based catalyst for enhanced hydrogen production from ammonia decomposition, Catalysis Today, 2021, ISSN 0920-5861).

The advantage of such a conversion module is that it eliminates the need for high heat for the conversion of ammonia in gaseous form into dihydrogen and dinitrogen, unlike conventional thermal cracking methods for which significant heat is required, depending on the catalyst used.

By “liquid source comprising ammonia”, it is meant a liquid source whose ammonia concentration is greater than 0. However, for economic and industrial reasons, a minimum concentration of at least 500 mg/l is preferred. The liquid source 11 comprising ammonia according to the present invention may be an effluent from a water treatment plant, an industrial or agricultural operation or any other effluent comprising ammonia. In particular, the liquid source may have undergone prior transformation, fermentation or non-fermentation steps. For example, the liquid source 11 may comprise fermented urine, or aged urine (known in English as “lant”) mixed or not with another liquid, the fermentation increasing the ammonia concentration by decomposition of the urea.

Even more preferably, and for economic and industrial reasons, an ammonia concentration of at least 3000 mg/l is preferred. In particular, in the case of a liquid source comprising 500 mg/l of ammonia, a fatal heat source, for example heat-emitting energy production sites, would allow evaporation and make it possible to achieve an economically feasible concentration. All means for increasing the ammonia concentration of a liquid source are conceivable for supplying the system of the present invention.

Thus, optionally but preferably, the treatment system 10 of a liquid source 11 of the present invention comprises a concentration module 16 of the ammonia in the liquid source. This concentration module 16 makes it possible to increase the ammonia concentration of the liquid source 11 so as to make this concentration sufficient for the treatment of the concentrated liquid source to be economically and industrially interesting.

In particular, the concentration module 16 of the present invention may comprise a filtration module by ultrafiltration, by nanofiltration, by direct osmosis, by reverse osmosis, or by electrodialysis. A combination of these modules may also be implemented. These filtration modules used for the present invention, which could be interchangeably called membrane separation modules, allow in particular the separation of dissolved materials and thus the obtaining of a concentrated flow and a diluted flow, also called concentrate/retentate and permeate respectively.

There represents a system for treating a liquid source comprising ammonia, and optionally phosphorus, according to the present invention. The system for treating the comprises the supply of a liquid source 11 to an extraction module 12 in the form of gaseous ammonia from the ammonia included in the liquid source 11. The extracted gaseous ammonia is then transferred to a conversion module 14 allowing the transformation of the extracted gaseous ammonia into nitrogen and dihydrogen 15, the conversion module 14 being a reactor using a non-thermal plasma coupled or not to catalysis, preferably a DBD reactor.

Optionally but preferably, the treatment system 20 of a liquid source 11 of the present invention comprises a concentration module 16 of ammonia in the liquid source, this concentration module 16 being able to be a filtration module by ultrafiltration, by nanofiltration, by direct osmosis, by reverse osmosis, or by electrodialysis. A combination of these modules can also be implemented.

The treatment system 20 of a liquid source 11 according to the also optionally includes a purification and/or separation module 21 for the nitrogen and dihydrogen extracted by the conversion module 14. In particular, such a module allows the reuse of dihydrogen without nitrogen or vice versa.

The treatment system 20 of a liquid source 11 comprising ammonia and phosphorus according to the may optionally comprise a first recovery module 23 for the phosphorus included in the liquid source 11 or the concentrated liquid source 11a after its concentration by the concentration module 16.

By “comprising phosphorus” is meant a liquid source whose phosphorus concentration is greater than 0. However, for economic and industrial reasons, a minimum concentration of at least 50 mg/l P-PO4 is preferred. The liquid source 11 comprising ammonia and phosphorus according to the present invention may be an effluent from a water treatment plant, an industrial or agricultural operation or any other effluent comprising ammonia and phosphorus. In particular, the liquid source may have undergone prior transformation, fermentation or non-fermentation steps. For example, the liquid source 11 may comprise fermented urine, or aged urine (known in English as “lant”) mixed or not with another liquid, the fermentation increasing the ammonia concentration by decomposition of the urea.

Even more preferably, and for economic and industrial reasons, an ammonia concentration of at least 150 mg/l is preferred. All means for increasing the phosphorus concentration of a liquid source are conceivable for supplying the system of the present invention. In particular, the concentration module 16 of the liquid source 11 can make it possible to increase the ammonia and/or phosphorus concentration so as to achieve economically and industrially preferred concentrations.

Alternatively or in addition, the treatment system 20 of a liquid source 11 comprising ammonia and phosphorus according to the may optionally include a second recovery module 24 for phosphorus included in the discharge liquid 13.

The second recovery module 24 of phosphorus in the discharge liquid 13 allows the recovery of phosphorus in the discharge liquid 13 by precipitation or by mineral or metallic crystallization, for the formation of struvite, calcium phosphates, brushite, hydroxyapatite, or others. In particular, the compounds formed depend on the materials available to transform them with the phosphorus in the discharge liquid 13.

The first phosphorus recovery module 23 allows the recovery of phosphorus in the liquid source 11 or the concentrated liquid source 11a by precipitation or by mineral or metallic crystallization, for the formation of struvite, calcium phosphates, brushite, hydroxyapatite, or others. In particular, the compounds formed depend on the materials available to transform them with the phosphorus in the liquid source 11 or the concentrated liquid source 11a.

The first phosphorus recovery module 23 and/or the second phosphorus recovery module 24 make it possible to obtain elements comprising phosphorus, in particular precipitates or crystallized elements which can be reused 25. By reuse, it is understood that the recovered product comprising phosphorus, in particular a precipitate or a crystallized element, by the first recovery module 23 and/or by the second phosphorus recovery module 24 is used in other processes, for example by using the struvite formed as fertilizer for agriculture.

The recovery of phosphorus by the first and/or by the second phosphorus recovery module 23, 24 can be carried out by a physicochemical treatment, consisting of the precipitation of phosphorus by adding, for example, a metal salt or an alkaline earth salt. For example, ferric chloride or calcium salts such as calcium chloride can be used. The phosphorus in precipitated form is then extracted in a separator, the phosphorus precipitated with the metal or alkaline earth salt being retained in the physicochemical sludge resulting from the separation.

In the case of a second recovery module 24 of phosphorus, for example in the form of struvite, in the discharge liquid 13, the extraction module 12 in the form of gaseous ammonia of the ammonia included in the liquid source 11 or in the concentrated liquid source 11a can be configured so as to carry out stripping operations beyond a predefined ammonia concentration threshold and to stop the stripping operations if the ammonia concentration in the liquid source 11 or the concentrated liquid source 11a is lower than this predefined concentration threshold.

In the case of a second phosphorus recovery module 24, alternatively or additionally, the extraction module 12 may be configured to perform stripping operations beyond a predefined residual ammonia concentration threshold in the discharge liquid 13 and to stop the stripping operations if the residual ammonia concentration is below the concentration threshold. Indeed, a residual ammonia concentration in the discharge liquid may be necessary in the case where an operator wishes to form a precipitate requiring ammonia with the second phosphorus recovery module 24. In the case where an operator wishes to form a precipitate not requiring ammonia with the second phosphorus recovery module, then it is not necessary to control the residual ammonia concentration in the discharge liquid 13, at the outlet of the extraction module 12.

In the case of a second phosphorus recovery module 24, alternatively or additionally, the extraction module 12 is configured so that the residual ammonia concentration in the discharge liquid meets a target objective, making it possible to optimize phosphorus recovery with the phosphorus recovery module 24.

Similarly, alternatively or additionally, the extraction module 12 in the form of gaseous ammonia from the ammonia included in the liquid source 11 can be configured so as to carry out stripping operations beyond a predefined phosphorus concentration threshold and to stop the stripping operations if the phosphorus concentration in the liquid source 11, in the liquid source 11a, or in the discharge liquid 13 is lower than this predefined concentration threshold.

In order to assess the ammonia and/or phosphorus concentrations in the liquid source 11, the concentrated liquid source 11a or in the discharge liquid 13, one or more sensors may be arranged at the inlet and/or inside and/or at the outlet of the extraction module 12 so as to measure the ammonia and/or phosphorus concentration. Such sensors may also or alternatively be arranged at the inlet and/or inside and/or at the outlet of the concentration module 16.

There also illustrates that the treatment system 20 of the present invention may comprise a purification and/or separation module 21 of the dinitrogen and dihydrogen 15 converted by the conversion module 14 from the ammonia extracted by the extraction module 12. This purification and/or separation module 21 notably allows the reuse of the dinitrogen and/or dihydrogen individually.

There also illustrates that the treatment system 20 of the present invention may comprise a methanation reactor 22 which receives the dihydrogen purified or separated by the purification and/or separation module 21. The methanation reactor typically allows the synthesis of methane (CH ₄ ) from dihydrogen (H ₂ ) and carbon dioxide (CO ₂ ).

There represents a treatment system 30 of a liquid source 11 as described in , further comprising optional reinjection means towards an anaerobic digester and a liquid/solid separation module.

The means of reinjection according to the correspond to one or more conduits allowing the transfer from the conversion means 14 and/or from the purification and/or separation module 21 to an anaerobic digester 31. In the case of a transfer from the conversion means 14, a mixture of dihydrogen and dinitrogen is transferred to the anaerobic digester 31. In the case of a transfer from the purification and/or separation means 21, it is only the purified and/or separated dihydrogen which is transferred to the anaerobic digester 31.

There also illustrates the possibility for the treatment system 30 of the present invention to form a complete cycle by connecting the anaerobic digester 31 to the inlet of the ammonia extraction module included in the liquid source 11. Indeed, the anaerobic digester makes it possible to obtain an anaerobic digester liquor (or a digestate) of which a portion, the liquid fraction of the anaerobic digester liquor obtained after separation in a solid/liquid separation module (for example by dehydration), can serve as liquid source 11.

In such an embodiment, which may be combined with the embodiments described above, the anaerobic digester liquor 31 may likely comprise too large a quantity of solids to be processed directly by the gaseous ammonia extraction module 12. In this case, a liquid/solid separation module 32 is required, making it possible to obtain, among other things, a liquid fraction of the anaerobic digester liquor 31. This module may be a module for separating solids from interstitial water, a dehydration module, a sedimentation module, a filtration module, a centrifugation module, or a combination thereof. Preferably or if necessary, the liquid fraction of the anaerobic digester liquor 31 after processing by the liquid/solid separation module 32 may be transferred to a concentration module 16 in order to obtain the concentrated liquid source 11a.

In a particular embodiment of the invention with a liquid source 11 comprising ammonia and phosphorus, an embodiment which can be combined with the previous embodiments described, the first or second phosphorus recovery module and the module for extracting the ammonia in the form of gaseous ammonia are combined in a single reactor. Thus, the precipitation of phosphorus can be done in the lower part of the reactor with a pH close to or below the pKa NH ₄ ⁺ /NH ₃ , the precipitation for example of struvite being more effective at a higher pH, while the stripping can be induced in an upper part of the reactor, where the pH will be above the pKa.

Advantageously, the single reactor comprising the stripping module and a phosphorus recovery module is configured to operate under vacuum. Advantageously also, gas injections, i.e. gas sparging, in this single reactor can be carried out to make the phosphorus recovery and gaseous ammonia stripping operations more efficient.

The present invention also relates to a method of treating a liquid source 11 comprising ammonia and optionally phosphorus. This treatment method can be carried out using any of the treatment systems previously described. The liquid source 11 comprising ammonia and optionally phosphorus as previously described is suitable for the method of the present invention.

The present invention thus also relates to a method for treating a liquid source 11 comprising ammonia, the method comprising a step of extracting gaseous ammonia from the ammonia included in the liquid source 11. This step is preferably carried out by a stripping module, even more preferably a vacuum stripping module. The liquid obtained at the end of this step therefore has a lower ammonia concentration than that of the liquid source 11 before this step. This liquid obtained at the end of this step is called the discharge liquid 13.

The gaseous ammonia extracted by the extraction step is then converted during a step of conversion of the extracted gaseous ammonia into dinitrogen and dihydrogen 15. This step is carried out using a reactor using a non-thermal plasma coupled or not to a catalysis, preferably a dielectric barrier plasma discharge (DBD) reactor. The use of such a reactor for the conversion of gaseous ammonia is advantageous because it makes it possible to avoid a high heat requirement, unlike conventional thermal cracking methods for which significant heat is required, this depending on the catalyst used.

The method of the present invention can be completed when the liquid source 11 also comprises phosphorus, the method then comprising a step of recovering phosphorus in the liquid source 11 and/or in the discharge liquid 13. This step can be carried out with a phosphorus recovery module as described in the systems of the present invention.

In such a case, the method may comprise receiving measurements by sensors making it possible to evaluate the concentration of ammonia and/or phosphorus so as to determine whether these concentrations exceed specific thresholds for which recovery of phosphorus is industrially interesting. In particular, these thresholds vary depending on the materials available to combine with the phosphorus and/or ammonia from the liquid source 11 or the discharge liquid, depending on the material desired after recovery and combination, in particular among the following materials: struvite, calcium phosphates, brushite, hydroxyapatite, or others. These thresholds may also vary depending on the choice of the operator, who may or may not prioritize the extraction and conversion of ammonia in the liquid source 11. Thus the operator is capable, and the treatment system makes it possible, to adapt the system according to an objective or one or more concentration thresholds.

The method may further comprise a step of reinjecting the dihydrogen and the dinitrogen 15 obtained at the end of the conversion step, or only the dihydrogen, into an anaerobic digester 31 or into a methanation reactor 22. In the case of a step of reinjecting only the dihydrogen, the method comprises the purification and/or separation of the dihydrogen and the dinitrogen using a purification and/or separation module 21.

In particular, the anaerobic digester 31 to which the dihydrogen or the dihydrogen and the dinitrogen 15 are reinjected can provide a liquid source comprising ammonia which can be reused for the method of the present invention. However, in such a case, the liquor from the anaerobic digester 31 probably requires prior treatment in order to reduce the quantity of solids. This step prior to the supply of the liquid source 11 comprising ammonia, for a step of extracting gaseous ammonia, comprises a step of liquid/solid separation and/or dehydration. In this case, a liquid/solid separation module 32 is necessary. This module can be a module for separating solids from interstitial water, a dehydration module, a sedimentation module, a filtration module, a centrifugation module, or a combination thereof.

In addition, the method may advantageously comprise a step of concentrating the ammonia and optionally the phosphorus included in the liquid source 11 before the step of extracting the gaseous ammonia from the ammonia included in the liquid source 11. This concentration step may be carried out by a filtration module by ultrafiltration, by nanofiltration, by direct osmosis, by reverse osmosis, or by electrodialysis. A combination of these modules may also be implemented.

The present invention also corresponds to an installation comprising a system as described previously and/or implementing the method as described previously.

The various embodiments presented in this description are not limiting and can be combined with each other. Furthermore, the present invention is not limited to the embodiments previously described but extends to any embodiment falling within the scope of the claims.

Claims (16)

Treatment system (10) of a liquid source (11) comprising ammonia, the system comprising an extraction module (12) in the form of gaseous ammonia of the ammonia included in the liquid source and producing a discharge liquid (13), and a conversion module (14) of the extracted ammonia into nitrogen and dihydrogen (15), the conversion module being a reactor using a non-thermal plasma coupled or not to a catalysis. Treatment system (10) according to claim 1, the system further comprising a module (16) for concentrating ammonia in the liquid source (11) and providing a concentrated liquid source (11a) of ammonia to the extraction module (12). Treatment system (10) according to any one of the preceding claims, the concentration module (16) comprising at least one filtration module by ultrafiltration, by nanofiltration, by direct osmosis, by reverse osmosis, or by electrodialysis. Treatment system (10) according to any one of the preceding claims, the extraction module (12) being a stripper, said stripper being configured to operate under vacuum. A treatment system (10) according to any preceding claim, the liquid source (11) comprising ammonia being fermented urine. Treatment system (20) according to any one of the preceding claims, the system further comprising a purification and/or separation module (21) of the nitrogen and dihydrogen extracted by the conversion module (14). Treatment system (20) according to any one of the preceding claims, further comprising means for reinjecting the nitrogen and dihydrogen (15) produced by the means for converting (14) the extracted ammonia, or means for reinjecting the purified dihydrogen and/or separated from the nitrogen, towards a methanation reactor (22). A treatment system (30) according to any preceding claim, the system further comprising, upstream of the concentration module (16), an anaerobic digester (31) supplying at least one anaerobic digestate liquor to a liquid/solid separation module and/or a dehydration module (32), the liquid/solid separation module and/or the dehydration module supplying a liquid fraction being the liquid source (11) comprising ammonia. Treatment system (20) according to claim 8, further comprising means for reinjecting the nitrogen and dihydrogen (15) produced by the means for converting (14) the extracted ammonia, or means for reinjecting the purified dihydrogen and/or separated from the nitrogen, towards the anaerobic digester (31). Treatment system (20) according to any one of claims 2 to 9, the liquid source further comprising phosphorus and the system further comprising a first recovery module (23) of the phosphorus included in the liquid source (11) or the concentrated liquid source (11a), the concentration module (16) of the ammonia in the liquid source also being a concentration module of the phosphorus present in the liquid source. A treatment system (20) according to any one of claims 2 to 10, the liquid source further comprising phosphorus and the system further comprising a second recovery module (24) of phosphorus included in the discharge liquid (13), the extraction module (12) being configured to maintain a residual concentration of ammonia in the discharge liquid. Treatment system (20) according to any one of claims 10 or 11, the extraction module (12) being a stripper, and the first or second phosphorus recovery module (23, 24) and the stripper being included in a single reactor. A method of treating a liquid source (11) comprising ammonia, the method comprising the following steps: a step of extracting gaseous ammonia from the ammonia included in the liquid source and producing a discharge liquid (13), and a step of converting the extracted gaseous ammonia into nitrogen and dihydrogen (15), the conversion step being carried out with a reactor using a non-thermal plasma coupled or not to catalysis. A method of treating a liquid source (11) according to the preceding claim, the liquid source further comprising phosphorus, and the method further comprising a step of recovering the phosphorus in the liquid source, and/or in the liquid source after a step of concentrating the phosphorus in the liquid source, and/or in the discharge liquid (13). Method for treating a liquid source (11) according to any one of claims 13 or 14, the method further comprising a step of reinjecting the dihydrogen and the extracted dinitrogen, or the dihydrogen alone after purification or separation of the dinitrogen, into an anaerobic digester (31) or into a methanation reactor (22). A method of treating a liquid source (11) according to any one of claims 13 to 15, the method further comprising a prior step of concentrating the ammonia included in the liquid source before the step of extracting gaseous ammonia from the ammonia included in the liquid source.