Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
  • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/005—Combined electrochemical biological processes
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B15/00—Operating or servicing cells
  • C25B15/02—Process control or regulation
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
  • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/16—Nitrogen compounds, e.g. ammonia
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2201/00—Apparatus for treatment of water, waste water or sewage
  • C02F2201/46—Apparatus for electrochemical processes
  • C02F2201/461—Electrolysis apparatus
  • C02F2201/46105—Details relating to the electrolytic devices
  • C02F2201/46115—Electrolytic cell with membranes or diaphragms

Definitions

• the invention relates to an electrochemical system for recovery of components from a waste stream.
• the recovery of components relates to recovery of ammonia (NH 3 ) and/or ammonium (NH 4 + ) such that the system provides for ammonia and/or ammonium recovery from a waste stream.
• Waste stream may involve municipal waste water and industrial waste water, for example.
• bio-electrochemical systems are known for recovery of nitrogen from an ammonium comprising fluid. Such recovery is described in WO 2013/105854, for example.
• An objective of the present invention is to provide an electrochemical system for recovery of components from a waste stream that is more effective and more efficient as compared to conventional methods.
• the system comprising a reactor that comprises:
• recovery compartment configured for recovering components, wherein the recovery compartment is separated from one or more compartments with a hydrophobic membrane;
• circuit connecting the anode and the cathode comprising a power source for providing an electric current.
• the system according to the present invention comprises a number of compartments.
• the system comprises at least four compartments, i.e. an anode compartment with at least one anode, a cathode compartment with at least one cathode, a feed compartment provided between the anode and cathode compartments that in use is provided with the waste stream, and a recovery compartment that is configured for recovering components.
• the anode(s) and cathode(s) are connected in a circuit, the circuit comprising a power source for providing an electric current.
• the compartments are separated with one or more ion-exchange membranes, and the recovery compartment is being separated from one or more of the other compartments with an hydrophobic membrane.
• the at least one ion exchange membrane separating the anode and cathode compartments is preferably one or more of the following: a cation exchange membrane (CEM), an anion exchange membrane (AEM), a bipolar exchange membrane (BEM) or a charge mosaic membrane (CMM).
• the membrane separating the anode compartment from the cathode compartment comprises a CEM, since transfer of NH 4 + from the anode compartment is most efficient using a CEM.
• the cathode and anode compartments are separated with one or more cation exchange membranes. This enables transport of the protons and ammonium between the different compartments. It will be understood that other configurations for the compartments are possible, and some examples of embodiments of the invention having another configuration will be discussed.
• Waste streams may involve municipal waste waters and industrial waste waters, for example. This may involve ammonia and/or ammonium rich waste water streams such as the effluent of an anaerobic digester, urine treatment etc.
• Industrial waste waters may relate to waste waters from food processing, paper industry, and agriculture. It will be understood that also other waste water streams, preferably with a substantial amount of a component, such as ammonia and/or ammonium, can be treated in the electrochemical system according to the present invention.
• ammonium will be understood as NH 4 + ions
• ammonia will be understood as NH 3 (for example in the gas phase (g) or in solution (aq)
• nitrogen recovery will be understood as the recovery of a nitrogen comprising compound, such as ammonium (NH 4 + ) and/or ammonia (NH 3 ) and/or nitrogen (N 2 ).
• some of the cations are transported from the anode to the cathode, for example protons (H + ).
• protons are produced in the anode compartment due to an oxidation reaction and pass through the membrane(s) to the cathode compartment.
• water is reduced to hydrogen gas at the cathode, and hydrogen is oxidized at the anode.
• hydrogen is oxidized at the anode.
• the rate of recovery of the component can be controlled with a current.
• the anodic and cathodic reactions require a low power input as energy can be recycled for the recovery for ammonia from various types of waste water, for example. Therefore, losses in the system determine the required energy input.
• the electrochemical system is used for recovery of ammonia via using a gas permeable hydrophobic membrane, which is preferably integrated in the cathode compartment or in an additional compartment.
• the hydrophobic membrane separates the recovery compartment from one or more of the other compartments.
• gas permeable hydrophobic membrane allows an effective ammonia recovery as compared to conventional ammonia stripping that is highly dependent on temperature and requires large volumes of gas flow involving a relatively high energy requirement.
• the anode compartment comprises an anode.
• the anode compartment comprises a so-called membrane electrode assembly (MEA) comprising an electrode, for example carbon black with platinum, and a Nafion proton/cation exchange membrane
• Ammonium is transported over a further CEM, for example a Nafion membrane, to the cathode compartment wherein the ammonium is deprotonated to ammonia involving the hydroxyl ions produced in the HER.
• the hydrogen (gas) produced in a cathode compartment is transported externally.
• the dissolved ammonia is transported over the gas permeable hydrophobic membrane, allowing transmembrane chemisorption (TMCS) to the recovery compartment that comprises an acid.
• TMCS transmembrane chemisorption
• ammonia is protonated in the presence of acid/protons to ammonium.
• suitable acids are: H 3 P0 4 , H 2 S0 4 , HC1, HN0 3 , H 2 C0 3 .
• concentration of the acid in the recovery compartment influences the maximum NH 4 + concentration that is achieved in the recovery compartment. It will be understood that other configurations according to the invention can be envisaged and the illustrated reactions and components depend on the conditions and components to be recovered.
• electrochemical system of the invention comprises a bio-anode.
• Providing the anode as a bio-anode results in a so-called bio-electrochemical system where electroactive microorganisms catalyse the anodic reaction and thereby improve the overall energy efficiency.
• the electroactive microorganisms catalyse the anodic reaction and thereby improve the overall energy efficiency.
• microorganisms at the anode preferably oxidize organic substrate from wastewater (e.g. sugars, fatty acids, organic acids, etc.). This results in a more efficient oxidation at the anode.
• the bio- anode potential may lower the voltage which has to be applied across the anode and cathode. This may decrease the power consumption of the system resulting in an efficient operation.
• the recycled hydrogen from the cathode may provide an easily accessible electron donor for the electro active microorganism either directly (hydrogen oxidation) or indirectly by a stepwise conversion to other organic substrate (e.g. volatile fatty acids) followed by their oxidation.
• organic substrate e.g. volatile fatty acids
• the use of different compartments enables the use of different conditions in the compartments to optimize the desired reactions.
• hydrogen gas
• the waste water comprises urine.
• the pH may be much higher, for example about 10, while the pH in the acid compartment preferably is below 6. It will be understood that depending on the actual components that are involved in the electrochemical system according to the invention the specific operational conditions can be different.
• the feed compartment is integrated with one of the other compartments.
• the feed compartment is integrated with the cathode compartment.
• an N- rich stream is directly added to the cathode compartment and ammonia can be extracted near the cathode using hydrophobic (TMCS) membrane(s) provided between an integrated cathode/feed compartment and a recovery compartment.
• TMCS hydrophobic
• H 2 is oxidized to H + .
• a feed compartment for example ammonia is acidified, preferably with adding feed water comprising NH 3 and wherein ammonia is protonated.
• a concentrate compartment for example NH 4 + is concentrated and deprotonated by OH (preferably formed at the cathode) to NH 3 .
• the concentrate compartment is combined with one of the other compartments and comprises a TMCS membrane to selectively remove NH 3 .
• the reduction reaction takes place and H 2 /OH is formed, for example.
• H 2 is recycled to the anode and OH is used to deprotonate NH 4 + .
• a recovery compartment for example NH 3 is recovered from the
• concentration compartment as HN 4 + in an acid solution.
• ammonium could be recovered/extracted from the concentrate compartment as a gas. It will be understood that some of the compartments can be combined.
• a four compartment embodiment will be discussed in detail relating to the setup shown in figure 1 having an anode compartment, a feed compartment, a cathode with concentrate compartment, and a recovery compartment.
• a five compartment embodiment can also be envisaged, for example involving two concentrate sub-compartments between the feed and recovery compartments and between the recovery and cathode compartments, and having an anode compartment.
• the anode compartment is separated from the feed compartment with a MEA
• the feed compartment is separated from the concentration compartment with a CEM
• the concentrate compartment is separated from the cathode compartment with an AEM
• the concentrate compartment is separated from the recovery compartment with a TMCS membrane.
• a three compartment embodiment may comprise an anode compartment that is separated from a combined feed-concentrate-cathode compartment with a MEA, and wherein the combined compartment is separated from the recovery membrane with a TMCS membrane that preferably is in close proximity to the cathode.
• the electrochemical system further comprises a recycling system connecting an outlet of the cathode compartment to an inlet of the anode compartment to enable recycling or recirculation of H 2 .
• the component that is recycled supplies a reactant to the anode compartment and extracts a gas produced in the cathode compartment. More preferably, this component comprises H 2 . It is shown that this enables an effective recovery of components, especially ammonia from a waste flow such as urine, by recycling hydrogen over the system, preferably between the cathode and the anode compartment. In such system, the recovery can be performed without requiring an external supply of a reactant involving a substantially high amount of energy.
• Recycling of H 2 enables effective and efficient recovery of components, such as NH 3 .
• the recycling in an embodiment of the system according to the present invention relates to internal recycling of H 2 in the system.
• the reactions in the system involving H 2 lower the required energy input of the system. This increases the energy efficiency of the system.
• an embodiment of the invention making use of the recycling of H 2 and the hydrophobic membrane in a (electrochemical/bioelectrochernical) cell/system enables an efficient recovery process.
• Ammonia recovery systems which rely on bioelectrochemical systems (Microbial Electrolysis Cells), which oxidize an organic matter at the anode and reduce water at the cathode, require a theoretical cell voltage higher than 0.12 Volts. Additionally, losses from anode and cathode overpotentials, membrane potential and transport losses will further increase the cell voltage.
• bioelectrochemical systems Microbial Electrolysis Cells
• Ammonia recovery systems which rely on water electrolysis (i.e. Electrochemical systems), require a theoretical cell voltage of 1.23 Volts. Additionally, losses from anode and cathode overpotentials, membrane potential and transport losses will further increase the cell voltage.
• the electrochemical system further comprises a concentrate/intermediate compartment between the feed and cathode compartments with the concentrate compartment comprising one or more separating ion exchange membranes.
• the concentrate compartment is provided between the feed compartment and the cathode compartment.
• this concentrate compartment further reactions can be performed.
• ammonium is deprotonated to ammonia due to the hydroxyl produced during the hydrogen evolution reaction or cathode reaction in the cathode compartment.
• the concentrate compartment is separated from the cathode compartment by an anion exchange membrane, for example.
• the dissolved ammonia is transported over the gas permeable hydrophobic membrane to the acid that is provided in the recovery compartment.
• hydrogen is produced and removed from the cathode compartment.
• the hydrogen that is produced is recycled to the anode compartment with the recycling system.
• ammonia is protonated, preferably in accordance with the process described in relation to the embodiment with at least four compartments.
• the recovery compartment is positioned adjacent the concentrate compartment with a hydrophobic membrane separating the concentrate compartment from the recovery compartment.
• the concentrate compartment is positioned between the feed and cathode compartments. It was shown that such configuration of compartments and membranes provides an effective and efficient recovery of components.
• ions are being transported between the compartments.
• AEM anion exchange membrane
• the cathode pH is relatively high at this stage due to cations, mostly NH 4 + and other metal ions (Na + , K + , Mg 2+ , Ca 2+ ), that may lead to a pH increase in the intermediate or cathode compartment.
• the hydrophobic membrane is positioned adjacent to a separating ion-exchange membrane.
• the flow channel provides at an optimal location for optimal ion concentrations, for example a location having a relatively high OH concentration and highest pH. This renders the
• the hydrophobic membrane is integrated with a separating ion-exchange membrane. This further improves the efficiency of the hydrophobic membrane and provides an effective means to assemble the reactor according to the present invention involving ion-exchange membranes and at least one hydrophobic membrane.
• the (gas permeable) hydrophobic membrane is provided as a number of tubular elements from a hydrophobic membrane material.
• the tubular elements are shaped as hollow fiber flow channels, tubular members or straw like channels.
• the tubular elements can optionally be bundled.
• other designs for the hydrophobic membrane can also be envisaged in accordance with the present invention.
• the use of a flow channel defining hydrophobic membrane enables gas extraction from the compartment and/or reactant supply. It is shown that this significantly improves the overall efficiency of the reactions that take place in the electrochemical system according to the present invention. Therefore, the efficiency of such system is improved due to the use of one or more flow channels defining hydrophobic membranes.
• the electrochemical system further comprises a fuel cell or engine configured for generating electricity with gasses removed from the reactor.
• electricity can be generated to further improve the overall energy efficiency of the electrochemical system according to the present invention. This may even result in a stand-alone application that can be operated in remote areas.
• SOFC solid oxide fuel cell
• the invention relates to a method for recovery of components from a waste stream, the method comprising the steps of:
• the method provides the same effects and advantages as those described for the electrochemical system.
• the recovery of components involves recovery of ammonia.
• the method treats urine that comprises several organic compounds and having an ammonium-nitrogen concentration as high as 10 g/1 or higher, for example.
• other ammonium comprising fluids can be treated.
• energy can be gained from the process, and the organic material and ammonia and/or ammonium can be removed from the (waste water) fluid.
• electrical energy can be generated.
• H 2 is recycled. More specifically, H 2 is recycled between the cathode and anode compartment(s). This provides an effective removal of components such as ammonium.
• FIG. 1 shows a reactor with an electrochemical system according to the invention
• FIG. 2 shows an alternative embodiment of an electrochemical system according to the invention.
• Electrochemical system 2 (figure 1) comprises reactor 4.
• reactor 4 comprises four compartments.
• Anode compartment 6 comprises anode 8.
• anode compartment 6 comprises inlet 10, recycling inlet 12 and outlet 14.
• Feed compartment 16 is separated from anode compartment 6 with cation exchange membrane 18.
• Cation exchange membrane 18 enables transfer of protons, or other cations, from anode compartment 6 to feed compartment 16.
• Feed compartment 16 is provided with inlet 20 and outlet 22 enabling a continuous or batch wise supply of waste water.
• the flow of cations 24 from anode compartment 6 is received in feed compartment 16.
• Cathode compartment 26 is separated from feed compartment 16 by cation exchange membrane 28.
• Cation exchange membrane 28 may enable transfer 30 of ammonium to cathode compartment 26.
• Cathode compartment 26 comprises cathode 32. Cathode 32 and anode 8 are connected in circuit 34. Cathode compartment 26 further comprises inlet 36, outlet 38 and recycling outlet 40. In the illustrated embodiment recycling system 42 connects recycling outlet 40 with recycling inlet 12 involving a tube or pipe.
• Recovery compartment 44 is separated from cathode compartment by hydrophobic membrane 46. Recovery compartment 44 is further provided with inlet 48 and outlet 50.
• electrochemical system 102 (figure 2) also comprises reactor 104 that is provided with anode compartment 106 with anode 108 and having inlets 110, 112 and outlet 114.
• Feed compartment 116 is separated by cation exchange membrane 118 from anode compartment 106 and comprises inlet 120 and outlet 122.
• Intermediate compartment 124 is separated from feed compartment 116 with cation exchange membrane 126.
• Intermediate compartment 124 further comprises inlet 128 and outlet 130.
• Cathode compartment 132 comprises cathode 134 and is separated from intermediate compartment 124 by anion exchange membrane 136.
• Cathode 134 and anode 108 are connected in circuit 138.
• Cathode compartment 132 comprises inlet 140, outlet 142 and recycling outlet 144 that is connected by recycling system 146 to recycling inlet 112 of anode compartment 106.
• recovery compartment 148 is separated from intermediate compartment 124 by hydrophobic membrane 150.
• Recovery compartment 148 comprises inlet 152 and outlet 154.
• the effluent of the H 2 recycling electrochemical system (HRES) of the present invention is to a large extent depleted of the TAN (in the experiments >73%), and the effluent still contains considerable concentrations of organic carbon, the effluent could be an interesting feed stream for anaerobic biological systems, such as a bioelectrochemical system (BES), to recover energy.
• BES bioelectrochemical system
• the experiments showed a relatively low energy demand as compared to other TAN recovery systems.
• the electrochemical system 2, 102 can be operated batch wise or continuously with a waste stream that may comprise ammonium such as urine.

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• 2016
  • 2016-08-29 NL NL2017383A patent/NL2017383B1/nl not_active IP Right Cessation
• 2017
  • 2017-05-16 EP EP17728944.4A patent/EP3504162A1/en not_active Withdrawn
  • 2017-05-16 WO PCT/NL2017/050304 patent/WO2018044153A1/en active Application Filing

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