"ELECTRODIALYTIC REACTOR AND PROCESS FOR THE TREATMENT OF

CONTAMINATED AQUEOUS MATRICES"

Technical field

This application relates to an electrodialytic reactor and a process for the treatment of contaminated aqueous matrices.

Background art

Global freshwater availability is under permanent stress. Of all water available on our planet only 2.5% is potable freshwater, of which, most is located in ice caps and only 0.3% is directly available for consumption. The United Nations Environment Programme (UNEP) has calculated that, due to increasing population, the global water consumption will rise dramatically over the coming years, leading to an increasing stress on available freshwater sources, increasing local drought risks and reducing the availability of potable water for consumption. Significant increases are mainly seen in subtropical regions, in Europe, in the Mediterranean region and central European areas. Global extraction trends are reflected in the scenarios of the UNEP Geo5 report, where Industrial water use comes in a second place and exhibits the risk of a tremendous growth in the coming decennia.

The European Environment Agency (EEA) states that about 44 % of total water abstraction in Europe is used for agriculture, 40 % for industry and energy production (cooling in power plants), and 15 % for public water supply. The main water consumption sectors are irrigation, urban and manufacturing industry. It is clear that both EEA and the UNEP call for action to increase the efficiency in water use. Quoting the UNEP 5 report: " Increasing water-use efficiency in all sectors is vital to ensure sustainable water resources for all uses". The materials manufacturing industry (e.g. building materials sector, concrete production) shall make an effort to be able to achieve a lower water use scenario. In industrial practice water is mostly seen as a cheap and always available consumable rather than a valuable and scarce resource. In industry, a change in the mind-set is needed towards the appreciation of water as a scarce good as stated in the Water Framework Directive (2000/60/EC) " Water is not a commercial product like any other but, rather, a heritage which must be protected, defended and treated as such". As an example:

Concrete is the 2 ^nd most consumed material

Water is the 1 ^st

water-cement ratio: weight of water to weight of cement used in a concrete mix 0.45 to 0.60

800 billion litters of water are estimated to be used, per year.

This change can be promoted by a paradigm shift already in place by some important stakeholders who influence and inspire the value chain in which they operate. The present innovation will contribute with high end technology for industrial propose, leading this sector to a circular economy with win-win solutions.

The present technology proposes a reactor with a specific purpose, that is the pre-treatment of different types of contaminated aqueous matrices for example, but not limited to, wastewater, cooling tower water, tap water with high content of salts, water from wells, groundwater in underground aquifers, for their further use in construction industry materials, reuse and irrigation purposes for example. This technology will avoid disadvantages of the classic electrodialytic process (EP0760718 Bl), will improve the quality of the final treated matrices and also the final materials .

Document EP0760718 Bl discloses a method for the decontamination of contaminated porous matrices based on a three-compartments reactor. In this reactor the contaminated solid matrices are placed in a central compartment while the electrodes are placed in lateral compartments. The electrode compartments are separated from the central compartment by ion exchange membranes. Regarding this document, the present application presents the following differences:

- Combines different stages (1 and 2) in the reactor - allowing for the movement of the contaminated aqueous matrices ;

- Places an electrolyte solution in the central compartment ;

- Places the contaminated aqueous matrices in the lateral compartments, wherein the matrices are in direct contact with the electrodes, promoting the electrodegradation;

- Possibility of shifting the separators (e.g. cation exchange membrane (CEM) with an anion exchange membrane) ;

- Recovery of the hydrogen produced during the electrolysis process, to be used in a fuel cell, in order to produce energy. Summary

The present application relates to an electrodialytic reactor (1) for the treatment of contaminated aqueous matrices comprising:

a central compartment (4), a lateral compartment (2), a lateral compartment (3), separators (7) (8), electrodes (5) (6), inlets (10) (13), outlets (11) (12) and power supply ( 14 ) , wherein :

electrode (5) is an anode and electrode (6) is a cathode ;

separator (7) is an anion exchange membrane and separator (8) is a cation exchange membrane;

the lateral compartments (2) (3) are adapted to receive the aqueous matrices;

the central compartment (4) is adapted to receive an electrolyte solution.

In one embodiment the lateral compartment (2) is separated from the central compartment (4) with separator (8), and the lateral compartment (3) is separated from the central compartment (4) with separator (7) .

In another embodiment the lateral compartment (2) comprises the anode (5) and the lateral compartment (3) comprises the cathode ( 6 ) .

In yet another embodiment the lateral compartment (2) is separated from the central compartment (4) with separator (7), and the lateral compartment (3) is separated from the central compartment (4) with separator (8) . In one embodiment the lateral compartment (2) comprises the cathode (6) and the lateral compartment (3) comprises the anode (5) .

In another embodiment the electrodes (5) (6) are made of mixed metal oxide coated with titanium, platinum coated with titanium or boron doped diamond with niobium subtract.

In yet another embodiment the separators (7) (8) are made of cross-linked co-polymers of vinyl monomers and containing quaternary ammonium anion exchange groups or sulfonic acid cation exchange groups.

In one embodiment the reactor (1) further comprises an outlet (15) .

In another embodiment the reactor (1) further comprises a proton-exchange membrane fuel cell (9) associated with outlet ( 15) .

In one embodiment the lateral compartment (2) comprises an inlet (10) and outlet (12) .

In another embodiment the lateral compartment (3) comprises an inlet (13) and outlet (11) .

In yet another embodiment the proton-exchange membrane fuel cell (9) is connected with the power supply (14) .

The present application also relates to a process for the treatment of contaminated aqueous matrices in reactor (1), comprising the following steps: introducing a raw aqueous matrix in the lateral compartment (2) comprising an electrode and a separator, through inlet (10);

applying of a current to the electrode therein;

electromigration of charged elements from the matrix through the separator and into an electrolyte solution in the central compartment (4);

transferring the matrix from the lateral compartment (2) through outlet (12), to the lateral compartment (3) comprising an electrode and another separator, through inlet (13) ;

applying of a current to the electrode therein;

electromigration of charged elements from the matrix through the separator and into an electrolyte solution in the central compartment (4);

collecting the treated matrix through outlet (11) .

In one embodiment the lateral compartment (2) comprises the anode (5) and the cation exchange membrane (8), and the lateral compartment (3) comprises the cathode (6) and anion exchange membrane (7) .

In another embodiment the lateral compartment (2) comprises the cathode (6) and the anion exchange membrane (7), and the lateral compartment (3) comprises the anode (5) and cation exchange membrane (8) .

In one embodiment the electrolyte solution has a concentration of 10 ² M.

In one embodiment hydrogen is recovered from the lateral compartment comprising the cathode (5) to feed a proton- exchange membrane fuel cell (9) and generate energy to the process .

General Description

The present application relates to an electrodialytic extraction reactor suitable for the removal of macro and micro elements from contaminated aqueous matrices.

Thus, it is possible to remove from a contaminated aqueous matrix the positively charged compounds in a first step and those elements with negative charge in a second step, assessing also differences in the pH, promoted by the influence of electrodes due to water electrolysis. These enhancements lead to an improvement of the final characteristics of the aqueous matrix and increase its value for further use.

In comparison with the technologies already in existence, the present technology provides the treatment of contaminated aqueous matrices, the combination of different reactions steps, the movement of the aqueous contaminated matrix through the different reactions steps, an electrolyte solution that will turn into a brine solution, placed in the central compartment of the reactor, the aqueous contaminated matrices are provided to the lateral compartments in contact with the electrodes promoting electrodegradation, a customizable reactor design, and the production, use and recovery of hydrogen.

The arrangement herein proposed will allow to remove from the contaminated matrices the elements with a positive charge, cations which will move to the central compartment and be captive due to the separator, in a first step and elements with a negative charge, anions which will move to the central compartment and be captive due to the separator in a second step. At the same time, in the second step, the production of hydrogen will allow the use of a fuel cell to auto-feed a portion of the process.

One of the applications predicted for the decontaminated matrices is their use in the construction sector to prepare construction materials.

The socio-economic impact of the construction sector ranges from 7% in the most developed countries to near 20% in fast growing economies. However, the traditional construction sector has an unequivocal problem in terms of sustainability. The environmental impacts of this activity are recognizably high, but most of the efforts to minimize them have not been successful so far. The innovation of the sector has not matched that of other industries. The sector needs a new paradigm and the eco-construction is a field in expansion, integrating a search for new materials, exchange of the resources' uses and their quality improvement. The present technology responds to one of the Societal Challenge identified by the European Commission, namely on 'Climate action, environment, resource efficiency and raw materials'. The reactor herein described is a reactor with a specific purpose that is the pre-treatment of different types of aqueous contaminated matrices for their further use in materials of manufacturing sectors. This technology avoids disadvantages of the classic electrodialytic process and improves the quality of the final treated matrices and consequently, the final materials. Additionally, one of the positive features of the final material when this technology is used as a pre-treatment of the aqueous matrices, is the change in the colour of the materials from grey to light brown, or in texture from rough to softer, depending of the matrix to be decontaminated, which can avoid the use of artificial pigments, adjuvants and increase the value in the sales and marketing of said materials.

Besides the concrete production application, the present reactor can fulfil other market needs. The three most promising alternatives include (1) municipal wastewater treatment plants (WWTP) tertiary treatment, (2) industrial wastewater treatment and (3) irrigation purposes.

First, the technology could be used to replace the last treatment stage (disinfection) in a WWTP, which generally involves three stages of treatment: primary, secondary and tertiary. Over the last decade, new classes of pollutants are being detected and reported worldwide in the wastewater streams. In addition, the disinfection used nowadays, mostly involving chloride or UV light, are expensive and with implication on the toxicity of certain contaminants. The present application, with its unique characteristics, can be a possible alternative to the tertiary treatment.

Second, the reactor can treat industrial wastewater. Most industrial plants have on-site facilities to treat wastewater so that the pollutant concentrations comply with national and/or local regulations concerning disposal of wastewaters into rivers, lakes, oceans, or to the WWTP. However, many on-site plants reach their limits in removing the contaminants to an adequate extent with existing technology and they also pay for the discharge. As mentioned before, the present technology can complement the existing solutions. This is particularly relevant for cooling towers wastewater with high content of salts and with high potential of reuse inside the facility, complying with the green label criteria for industries. Third, the present technology has the potential to treat water with the final purpose of irrigation, since the main problem, commonlly, is the high conductivity, meaning high salts content. Since the reactor will not totally deionize the treated wastewater it will still have important elements to the soil, if applicable, and non-hazardous to another application. The reactor can be incorporated in a truck, for instance, and the treated aqueous contaminated matrix can be distributed .

The application of this reactor as a pre-treatment of aqueous contaminated matrices, considered waste and turned into a resource, prior to their use will originate benefits, such as :

Reduction of more than 75% freshwater intake - by closing water loops internally, the need for freshwater intake will be reduced;

Decrease different types of wastewater volume discharge - in wastewater treatment plants, the treated wastewater from secondary clarifiers can be fully reused;

Wastewater treatment plants from end-of-line waste process to resource production because wastewater treatment in wastewater treatment plants are costly. Therefore, cost-effective water treatment solutions will increase the competitive position of the plants and contribute for financial benefits;

Accessible/modular solutions that fit in any industrial settings - solutions will need to be scalable over orders of magnitude. This technology will be easy to integrate in already existing plants. Industries will be able to control the waste streams as a resource in their own business or to other industries. To the final specific application - construction industry sector:

a. Avoid contaminated construction materials;

b. Fine tune contaminated matrices, by the manipulation of the pH and the removal of main concern contaminants; in the electrodialytic conventional processes, mostly in liquid matrices, the problem is the acid pH achieved in the end, resulting from the acid front created by the H ⁺ produced in the anode compartment. In the present invention this will not happen due to the configuration of the reactor. Also, the feature of controlling the pH may increase the value in the market.

c. An aqueous matrix that fulfils the industry standards .

Benefits of the present technology compared to other patents and technologies:

^• f No reagent (acid or base) is used/added during the presently described process, promoting the sustainable image of the sector to be reused;

^• f Since the electrodes are placed in contact with the aqueous matrices under treatment, they may promote not only transportation of relevant ions, but also the electrodegradation of the contaminants in the aqueous matrix at the same time. Thus, the range of contaminants that can be treated is enlarged;

^• f Acidification and alkalization of matrices in the stages of the treatment process, in order to promote at the same time, removal of contaminants and giving the aqueous contaminated matrices similar characteristics to freshwater; ^• f The acidic conditions and corrosion of the anode are easily controlled. As the H ⁺ produced in the anode compartment will migrate to the cathode compartment and will be blocked due the cationic exchange membrane, it will not be possible to return to the anode or produce any acid front as in a conventional reactor. In addition, because the continuous inlet of effluent, the acid conditions are not so aggressive. This will be an advantage for scale implementation;

^• f A portion of the energy consumed by the electro-based treatment can be auto-fed by the use of a fuel cell, decreasing the carbon footprint. Comparing to the conventional cell, the hydrogen flow rate of the present technology is 60% faster.

Brief description of drawings

For easier understanding of this application, figures are attached in the annex that represent the preferred forms of implementation which nevertheless are not intended to limit the technique disclosed herein.

The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

Figure 1 illustrates one embodiment of the reactor of the present application wherein the reference numbers refer to: 1 - reactor; 2 - lateral compartment; 3 - lateral compartment; 4 - central compartment; 5 - electrode; 6 - electrode; 7 - separator; 8 - separator; 9 - fuel cell; 10 - inlet for raw aqueous matrix; 11 - outlet for treated aqueous matrix; 12 - outlet of matrix; 13 - inlet of matrix; SI - Stage 1; S2 - Stage 2; 15 - outlet for hydrogen.

Figure 2 illustrates the reactor of the present application connected to a fuel cell, wherein the reference numbers refer to: 1 - reactor; 2 - lateral compartment; 3 - lateral compartment; 4 - central compartment; 5 - anode; 6 - cathode; 7 - anion exchange membrane; 8 - cation exchange membrane; 9 - proton-exchange membrane fuel cell; 14 - power supply; 15 - outlet for hydrogen.

Figure 3 illustrates a vertical configuration of reactors (1) arranged in vertical assemblying, wherein the transfer of matrices from compartment (2) of one reactor (1) to compartment (3) of another reactor (1) at different height levels by means of gravitational flow.

1 - Reactors in sequence; 2 - lateral compartment; 3 - lateral compartment; 4 - central compartment; 5 - anode; 6

- cathode; 7 - anion exchange membrane; 8 - cation exchange membrane; 9 - proton-exchange membrane fuel cell;

10 - inlet for raw aqueous matrix; 11 - outlet for treated aqueous matrix; 12 - outlet of matrix from stages; 13 - inlet of matrix to stages; 15 - outlet for hydrogen; 16 - reservoir .

Figure 4 illustrates one embodiment of the reactor of the present application wherein the reference numbers refer to: 1 - reactor; 2 - lateral compartment; 3 - lateral compartment; 4 - central compartment; 5 - electrode; 6 - electrode; 7 - separator; 8 - separator; 9 - fuel cell; 10

- inlet for raw aqueous matrix; 11 - outlet for treated aqueous matrix; 12 - outlet of matrix from stage 1; 13 - inlet of matrix to stage 2; SI - stage 1; S2 - stage 2; 15 - outlet for hydrogen.

Description of embodiments

Now, preferred embodiments of the present application will be described in detail with reference to the annexed drawings. However, they are not intended to limit the scope of this application.

The present application relates to an electrodialytic extraction reactor suitable for the treatment of contaminated aqueous matrices by removing macro and micro elements. The present application also relates to a process for the removal of said macro and micro elements from contaminated aqueous matrices. Additionally, the technology provides a control of pH in different stages of the treatment, depending on the final application of the matrix. At the same time, the process occurring in the reactor produces above 90% of pure hydrogen that can auto-feed part of the energy needed to the process workability. Thus, it allows for the use of a fuel cell to decrease part of the energy consumed during the process.

In the end of the process, the treated matrices can be employed in a variety of applications.

Thus, in one stage of the process, occurring at the anode compartment, the pH of the contaminated aqueous matrices will be acidified. After a few hours of treatment, between 2 and 12 hours, depending of the conductivity and the type of wastewater the matrices pass to another compartment. In another stage of the process in the cathode compartment, it will turn the pH of the matrices to alkaline conditions, allowing the matrices to be suitable for the final reuses. Both stages can be performed up to 24 hours, after which the conductivity is too low for the process to continue running properly .

The transfer of the matrices between stages can be performed by means of pumps or differences of height levels using gravity force.

These changes do not change the efficiency of the removal, but the removal process will be slower compared to the three- compartments reactors in existence.

The current three compartment cell process is faster that the process cannot be controlled well, leading to a loss of the current density intend to be applied.

99% of removal of salts can be achieved in the conventional cell, but the advantages of the present technology encompass less hard matrices in the end, still approximately 70% of the removal, and offers a dynamic process which is easier to work .

The present technology is less aggressive to the final quality of the matrices, having still some nutrients for e.g. soil. Therefore, the process implemented in the currently disclosed reactor will be able to remove macro and micro elements such as anions, wherein the removal of salts is above approximately 75%, elements, heavy metals and nutrients wherein the removal is approximately between 40 and 72%, or removal of dissolved organic matter to approximately 70%. The findings will increase the possibility of having a resource of quality, similar to the freshwater that is consumed in the production of construction materials or to irrigation purposes. The macro and micro elements intended to be removed are Ca ²⁺ , Zn ²⁺ , Cl , S0 ₄ ² d NO3-, P but not limited to.

According to Figures 1 to 4, the electrodialytic extraction reactor (1) comprises three sequential compartments, wherein two lateral compartments (2) (3) comprise electrodes (5) (6), and a central compartment (4) .

Reactor

Central compartment

The central compartment (4) is adapted to receive an electrolyte solution to be, over the time, concentrated with all the micro and macro elements removed from the matrix under treatment. The electrolyte solution is selected from a list comprising, but not limited to, sodium nitrate, sodium chloride, sodium sulphate. In one embodiment the electrolyte solution has a concentration of 10 ² M, but not limited to. It is an independent compartment, separated from the aqueous contaminated matrices lateral compartments (2) (3) by separators ( 7 ) ( 8 ) .

The advantage of having only one electrolyte solution, as brine solution, is the possibility to recover the elements removed during the process or even produce, e.g perchlorate, from the electrolyte solution. In addition, the configuration allows the easy replacement of the brine solution by a clean one, without stopping the process.

Lateral compartments

There are two lateral compartments in reactor (1) which are adapted to receive the aqueous contaminated matrix. Each compartment (2) (3) comprises each electrode (5) (6) . The lateral compartments (2) (3) are physically separated from the central compartment (4) by separators (7) (8) .

In one embodiment, as shown in Figure 1 and 2, the lateral compartment (2) is separated from the central compartment (4) by separator (8), and the lateral compartment (3) is separated from the central compartment (4) by separator (7) .

Electrodes

The electrodes used can be, for exemple, mixed metal oxide, such as Ir0 ₂ + Ru0 ₂ , coated with titanium; platinum coated with titanium or boron doped diamond with niobium subtract. The reactor (1) comprises pairs of electrodes, the anode (5) and cathode ( 6 ) .

In one embodiment, as shown in Figure 1 and 2, the anode (5) is placed in the lateral compartment (2), and the cathode (6) is placed in the lateral compartment (3) .

During the treatment process, an electric field in the form of a direct current is applied to the electrodes (5) (6), in each stage of the process. In each stage, the current will result in the following electrolytic half-reactions at the electrodes (reaction R1 and R2 ) :

Anode: 2H ₂ 0 —► 0 ₂ (g) + 4H ⁺ + 4e (Rl)

Cathode: 4H ₂ 0 + 4e —► 2H ₂ (g) + 40H (R2)

The half-reactions result in that the pH near the anode will decrease, due to the production of protons and the pH near a cathode will increase due to the production of hydroxide ions, when a current is supplied. During electrolysis, the pH of the matrix in contact with the anode will decrease due to the reaction R1. The cations removed from the matrix typically include calcium, magnesium, silica, potassium, nickel, sulphur ions and/or heavy metals, and/or other cations. Due to the reaction R2, the pH of the matrix in contact with the cathode will increase. The anions removed from the matrix typically include sulphates, nitrates, chlorides, and/or other anions.

Separators

The separators (7) (8) are ion exchange membranes. The membranes are an ion selective comprised of cross-linked co polymers of vinyl monomers and containing quaternary ammonium anion exchange groups or sulfonic acid cation exchange groups .

They are membranes made of polymers with charged surfaces that promote high permselectivity, low electric resistance, good mechanical/ form stability and high chemical, thermal stability, long-term resistance to aqueous acid solutions, high dimensional stability in solutions of different compositions, high resistance to fouling by organic materials, chlorine stability.

Two types of membranes are key to the electrodialytic process: a cation exchange membrane and an anion exchange membrane. Their surface attracts dissolved ions with the opposite charge, counter-ions, from the pore water of the membranes. Counter-ions will be transported through the membrane due to electrical current and co-ions, with the same charge as the membrane's surface, will be rejected. The membranes allow the regulation of ion fluxes, thus selecting ions that reach the electrode compartments. Separator (7) is an anion exchange membrane and separator (8) is a cation exchange membrane.

In one embodiment, as shown in Figures 1, 2 and 3, an anion exchange membrane (7) separates the lateral compartment (3) from the central compartment (4), and a cation exchange membrane (8) separates the lateral compartment (2) from the central central compartment (4) . This embodiment comprises the anode (5) in the lateral compartment (2) and the cathode (6) in the lateral compartment (3) .

Outlet and Inlet

According to Figures 1, 2, 3 and 4, the reactor (1) comprises an inlet (10) for the raw aqueous matrix to enter compartment (2) . Said compartment (2) comprises an outlet (12) wherein the matrix treated in one stage is transported to inlet (13) and feed the lateral compartment (3) for the other stage of the process. After these two stages, there is an outlet (11) through which the treated aqueous matrix is removed.

In one embodiment, the lateral compartment comprising the cathode (6) comprises an outlet for hydrogen (15) .

In one embodiment, the flow in the inlets and outlets is performed by tubes with pumps or with gravity forces combined. In another embodiment the flow in the inlets and outlets is performed with a difference in height levels by means of gravitational flow, as shown in Figure 3.

Optionally, as shown in Figures 1,2 and 3, the hydrogen is collected from the lateral compartment comprising the cathode (6), through an outlet (15), with pumps to a reservoir (16), to use in a proton-exchange membrane fuel cell (9) or to sell, with hydrogen purity above 90%. The energy produced by the proton-exchange membrane fuel cell (9) can be connected to a power supply (14) that is feeding the reactor ( 1 ) .

Other features

As shown in Figure 2, the reactor (1) of the present application additionally comprises a power supply (14) .

Customizability

According to Figure 4, the reactor (1) of the present application is customizable in order to achieve acid matrices at the end of the treatment process. With that aim, the anode

(5) is placed in the lateral compartment (3), and the cation exchange membrane (8) separates the lateral compartment (3) from the central compartment (4) . Additionally, the cathode

(6) is placed in the lateral compartment (2), and the anion exchange membrane (7) separates the lateral compartment (2) from the central compartment (4) .

Process

In general terms, the process of treatment of contaminated aqueous matrices in the reactor (1) comprises the following steps :

introducing a raw aqueous matrix in the lateral compartment (2) comprising an electrode and a separator, through inlet (10);

applying a current to the electrode therein;

electromigration of charged elements from the matrix through the separator and into an electrolyte solution in the central compartment (4);

transferring the matrix from the lateral compartment (2) through outlet (12), to the lateral compartment (3) comprising an electrode and another separator, through inlet (13) ;

applying a current to the electrode therein;

electromigration of charged elements from the matrix through the separator and into an electrolyte solution in the central compartment (4);

collecting the treated matrix through outlet (11) .

Reactions of electrodegradation, electromigration and electrolysis, occur in and through the lateral compartments (2) (3) of reactor (1) .

In one embodiment, and according to the reactor (1) in Figures 1, 2 and 3, the treatment of the contaminated aqueous matrices in the reactor comprises two stages with the following steps:

Stage 1 (SI) : electro-process acidification of the contaminated aqueous matrices, which occurs at the anode side of reactor (1) :

Introduction of the raw aqueous matrix in the lateral compartment (2) of reactor (1) wherein the cation exchange membrane (8) allows only the passage of cations through it and an inert electrode (anode) , and application of a positive current in the anode (5); leading to:

- Electrodegration of some contaminants of the aqueous matrix, oxidation of the compounds due to the generation of protons (H ⁺ ) ;

- Electromigration of cations to the electrolyte solution in the central compartment (4) . Cations will be trapped in the central compartment (4) due to the presence of the anion exchange membrane (7), placed in the opposite side . Once the electrodialytic process of Stage 1 is completed, the resulting half treated matrix goes through to Stage 2 of the electrodialytic process, from an outlet (12) on the compartment (2) comprising the anode (5) to an inlet (13) on the compartment (3) comprising the cathode (6) . At the same time, a new batch of contaminated aqueous matrix is introduced in the lateral compartment (2) by an inlet (10) to start Stage 1, making a sequential treatment possible.

Stage 2 (S2) ; electro-process alkalization of contaminated aqueous matrices and generation of ¾, which occurs at the cathode side of reactor (1) :

The anion exchange membrane (7) allows only the passage of anions through it and an inert electrode (cathode) , and application of a negative current in the cathode (6), leading to :

- Electrodegration of some contaminants of the contaminated aqueous matrix, reduction of the compounds due to the generation of hydroxide ions (Oth) .

- Electromigration of anions to the electrolyte solution in the central compartment (4) . Anions will be trapped in the central compartment (4) due to the presence of the cation exchange membrane (8), placed in the opposite side .

- Alkalization of the aqueous matrix for further application;

- Electrolysis reaction at the electrode, water reduction at the cathode, which can allow hydrogen recovery to be used in a fuel cell (9) :

4H ₂ O(0 + 4e ® 2H ₂ (g) + 40H ^~ E° _athode (25°C) = 0 V In one embodiment, the hydrogen produced at this stage is either recovered through outlet (15) and collected into a reservoir (16) , that can be sold or used in a fuel cell (9) .

In summary, in one embodiment the process comprises the following steps:

- introducing a raw aqueous matrix in compartment (2) comprising the anode (5) and the cation exchange membrane (8) through inlet (10);

- applying of a positive current to the anode (5) therein;

- electromigration of positively charged elements from the matrix through the cation exchange membrane (8) and into an electrolyte solution in the central compartment (4) ;

- transferring the matrix from the lateral compartment

(2) through outlet (12), to the lateral compartment (3) comprising the cathode (6) and the anion exchange membrane (7) through inlet (13);

- applying a negative current to the cathode (6) therein;

- electromigration of negatively charged elements from the matrix through the anion exchange membrane (7) and into an electrolyte solution in the central compartment (4) ;

- collecting the treated matrix through outlet (11) .

In another embodiment of the process, in order to obtain acidic matrices at the end of the treatment process, the process occurs in the embodiment of reactor (1) shown in Figure 4, and the process comprises the following steps:

Stage 2 (S2) ; electro-process alkalization of contaminated aqueous matrices and generation of ¾, which occurs at the cathode side of reactor (1) : The anion exchange membrane (7) allows only the passage of anions through it and an inert electrode (cathode) , and application of a negative current in the cathode (6), leading to :

- Electrodegration of some contaminants of the contaminated aqueous matrix, reduction of the compounds due to the generation of hydroxide ions (Oth) .

- Electromigration of anions to the electrolyte solution in the central compartment (4) . Anions will be trapped in the central compartment (4) due to the presence of the cation exchange membrane (8), placed in the opposite side.

- Alkalization of the aqueous matrix for further application;

- Electrolysis reaction at the electrode, water reduction at the cathode, will allow hydrogen recovery to be used in a fuel cell (9) :

4H ₂ O(0 + 4e ® 2H ₂ (g) + 40H ^~ ; E _c ° _athode (25°C) = 0 V

Once the electrodialytic process of Stage 2 is completed, the resulting half treated matrix goes through to Stage 1 of the electrodialytic process, from an outlet (12) on the compartment (2) comprising the cathode (6) to an inlet (13) on the compartment (3) comprising the anode (5) . At the same time, a new batch of contaminated aqueous matrix is introduced in the lateral compartment (2) by an inlet (10) to start Stage 2, making a sequential treatment possible.

Stage 1 (SI) : electro-process acidification of the contaminated aqueous matrices, which occurs at the anode side of reactor (1) :

The cation exchange membrane (8) allows only the passage of cations through it and an inert electrode (anode) , and application of a positive current in the anode (5); leading to :

- Electrodegration of some contaminants of the aqueous matrix, oxidation of the compounds due to the generation of protons (H ⁺ ) .

- Electromigration of cations to the electrolyte solution in the central compartment (4) . Cations will be trapped in the central compartment (4) due to the presence of the anion exchange membrane (7), placed in the opposite side .

In one embodiment, the hydrogen produced at this stage is either recovered through outlet (15) and collected into a reservoir (16) , that can be sold or used in a fuel cell (9) .

In summary, in one embodiment the process comprises the following steps:

- introducing a raw aqueous matrix in the lateral compartment (2) comprising the cathode (6) and the anion exchange membrane (7) through inlet (10);

- applying of a negative charge to the cathode (6) therein;

- electromigration of charged elements from the matrix through the anion exchange membrane (7) and into an electrolyte solution in the central compartment (4);

- transferring the matrix from the lateral compartment (2) through outlet (12), to the lateral compartment (3) comprising the anode (5) and the cation exchange membrane (8) through inlet (13);

- applying a positive charge in the anode (5) therein;

- collecting the treated matrix through outlet (11) . There is a potential to turn the electrodialytic treatment energy more self-sufficient, using the hydrogen produced during the process or collecting it to further sold. A proton-exchange membrane fuel cell (9) that uses hydrogen gas for the conversion of chemical energy into power needs, is the choice for this purpose, since it is a viable solution to curb the energy-related CO2 emissions. The proton-exchange membrane usually acts as both transport medium for protons, electron insulator, and gas separator between the hydrogen and oxygen compartments. In a proton-exchange membrane fuel cell, two reactions, oxidation and reduction occurs at two separate electrodes: the anode and the cathode, respectively. At the cathode side the reaction:

2H ⁺ (aq) + 2e 2H2(g),

produces protons and electrons, which are then used to reduce oxygen into water and hydrogen into energy. In a proton- exchange membrane fuel cell, the choice of fuel is a key point for the performance and efficiency. In the present technology the hydrogen produced during the process, due to the water hydrolysis, will be used as fuel supply. The O2 gas is taken directly from the air by natural convection.

In one embodiment, 3 to 10% of the energy consumed by the electro-based treatment can be auto-fed by the use of the fuel cell. However, this number can vary depending on the matrix that is under treatment.

In one embodiment of the present technology, at least two reactors (1) can be assembled vertically on top of each other. In another embodiment, at least two reactors (1) can be assembled horizontally next to each other. Examples

An optimal combination was already achieved with: acid media - break complexes between elements (e.g. removal of Ca ²⁺ , Zn ²⁺ ) ; alkaline media - removing e.g. salts (Cl-, SC>4 ² ) , electrodes in contact with the contaminated matrices - electrodegradation .

Tests performed to the matrix after treatment:

º Salts content: Chloride 75% removal; sulfates 72% removal, in 2h 62% of the chloride was in the central compartment .

º pH in the final matrix to be further use: 9-10;

º Law parameters: COD5 93% removal; COD 52% removal.

Tests performed to the materials made with the treated matrices with the present technology:

º Compressive tests: mortars with 7 days of age (39 MPa); mortars with 14 days of age (47 MPa); mortars with 28 days of age (51 MPa) ;

º Setting times: compared to the reference (made with tap water), either is the same time or is faster by 20 minutes; º Workability: compared to the reference (made with tap water) the slump increased by 25 mm;

º pH of the material = same as the reference.

Fuel cell - the flow rate of hydrogen, compared with a conventional cell, is 60% faster, when effluent was used, as the aqueous contaminated matrices to be treated.

The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 778045.