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WO2011011829A1 - Système de pile bio-électrochimique - Google Patents

Système de pile bio-électrochimique Download PDF

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Publication number
WO2011011829A1
WO2011011829A1 PCT/AU2010/000959 AU2010000959W WO2011011829A1 WO 2011011829 A1 WO2011011829 A1 WO 2011011829A1 AU 2010000959 W AU2010000959 W AU 2010000959W WO 2011011829 A1 WO2011011829 A1 WO 2011011829A1
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Prior art keywords
zone
aqueous solution
electrode
bioelectrochemical cell
bioelectrochemical
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English (en)
Inventor
Ka Yu Cheng
Ralf Cord-Ruwisch
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Murdoch University
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Murdoch University
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Priority claimed from AU2009903544A external-priority patent/AU2009903544A0/en
Application filed by Murdoch University filed Critical Murdoch University
Priority to AU2010278674A priority Critical patent/AU2010278674A1/en
Publication of WO2011011829A1 publication Critical patent/WO2011011829A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/16—Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a bioelectrochemical cell system and methods for treating aqueous solutions, such as wastewater.
  • Wastewater is typically treated to remove undesirable contents and provide an effluent that can safely be returned to the environment.
  • Bacteria can assist in this process, particularly in respect of breaking-down ammonia that may be present in the wastewater.
  • the biological reaction by which ammonia is removed involves the conversion, first, aerobically, of the ammonia and other nitrogen-containing compounds to nitrates through bacterial nitrification; followed by a second step in which anoxic bacterial denitrification converts the nitrates into nitrogen gas, which is then separated from the wastewater.
  • Nitrification is performed under aerobic conditions by slow-growing autotrophic nitrifying bacteria, using oxygen to convert ammonia to nitrite and then to nitrate.
  • denitrification is performed by heterotrophic bacteria that require anoxic conditions and a source of electrons, typically organic material to convert nitrate into nitrogen gas.
  • the electrons are usually provided in the form of oxidisable organic and inorganic compounds in the wastewater.
  • the activated sludge (AS) process is currently the most widely adopted biological process for wastewater treatment. It is an energy intensive process, in which air (oxygen) is actively transported, either by surface turbines or submerged diffusers, into wastewater, in order to maintain an aerobic system and the activated sludge (a highly concentrated bacterial consortium) in suspension.
  • the activated sludge degrades the organic contaminants in the wastewater by using dissolved oxygen as the terminal electron acceptor.
  • For each m 3 of wastewater approximately 8 m 3 of air is required (Lee and Lin (2000) Handbook of Environmental Engineering Calculations).
  • Such an active aeration process leads to about 60-80% of the total operational cost of the entire wastewater treatment process.
  • the energy demand of aeration in AS processes lies fundamentally on the mass transfer of air to water.
  • oxygen-equivalents instead of transferring oxygen from a gas- into a liquid-phase, required for the organic removal in a wastewater.
  • the "oxygen-equivalents” can be indirectly supplied in the form of an electron accepting (i.e. oxidizing) surface (e.g. inert carbon electrode), in order to optimize aeration efficiency or to minimize aeration without compromising treatment efficiency.
  • an electron accepting (i.e. oxidizing) surface e.g. inert carbon electrode
  • BESs bioelectrochemical cell systems
  • MFCs microbial fuel cells
  • MECs microbial electrolysis cells
  • a BES has several features. Firstly, an electron donor (e.g. organics present in a wastewater) is oxidized by an electrochemically active anodophilic biofilm which can subsequently transfer the liberated electrons to an electrode (anode). Secondly, these electrons at the anode are driven by a potential gradient and flow toward a cathode via an external conductive circuit. Electrical energy is thereby generated if a suitable resistive load is located between the two electrodes. Thirdly, the electrons at the cathode react with a soluble electron accepting species (e.g. oxygen) which itself becomes reduced.
  • a soluble electron accepting species e.g. oxygen
  • BES processes regardless of design, for example trickling filter or sequencing batch reactor, are limited by: (1) the poor cathodic reaction of oxygen reduction; and (2) the build-up of a pH gradient between anode and cathode over time, which leads to an increased voltage loss (i.e. overpotential) of the BES. Further, it is this so-called pH splitting phenomenon, which can block the electron flow and operation of the BES.
  • the continual need for pH control is known to be a significant cost and energy factor in BES wastewater treatment.
  • either a proton (H+) or a hydroxide ion (OH-) serves as the migrating ionic species.
  • protons are continuously consumed for the reduction of oxygen or generation of hydrogen gas, for example, at a cathode, and also the concentrations of both protons and hydroxide ions are several order of magnitudes lower compared to most other ionic species.
  • concentrations of both protons and hydroxide ions are several order of magnitudes lower compared to most other ionic species.
  • pH splitting phenomena leads to a decrease in the driving force of the system (i.e.
  • a loop-concept has been proposed as a solution to overcome the aforementioned pH limitation during BES operation (Freguia et al., (2007b) Sequential anode-cathode configuration improves cathodic oxygen reduction and effluent quality of microbial fuel cells, Wat. Res., 42, 1387-1396). Specifically, the acidified anodic effluent is used as the influent for the cathode compartment in a two-compartment configuration. However, such operation depends heavily on mechanical pumping of wastewater through the system (Clauwaert et al. (2009) Litre-scale microbial fuel cells operated in a complete loop. Appl. Microbiol.
  • the present invention provides a bioelectrochemical cell system comprising: an upper portion; a lower portion, adapted to retain an aqueous solution; and an electrode, the electrode having a first zone and a second zone, wherein, the electrode is provided within the cell, the first zone and the second zone of the electrode are in electrical communication and, in use, the first zone of the electrode is at least partially immersed in an aqueous solution retained in the lower portion of the cell such that, the first zone is anodic, and wherein at least part of the second zone of the electrode is remote from the aqueous solution such that, the second zone is cathodic.
  • the bioelectrochemical cell system comprises: an upper portion; a lower portion, adapted to retain an aqueous solution; and an electrode, the electrode having a first zone and a second zone, wherein, the electrode is provided within the bioelectrochemical cell, the first zone and the second zone of the electrode are in electrical communication and, in use, the first zone of the electrode is at least partially immersed in an aqueous solution retained in the lower portion of the bioelectrochemical cell such that, the first zone is anodic, and wherein at least part of the second zone of the electrode is remote from the aqueous solution such that, the second zone is cathodic.
  • the first zone and the second zone of the electrode of the bioelectrochemical cell system alternate, such that the second zone is at least partially immersed in an aqueous solution retained in the lower portion and at least part of the first zone of the electrode is remote from the aqueous solution.
  • the aqueous solution circulates with the first zone and the second zone of the electrode alternating in position, thereby reducing the build-up of a pH gradient between first and second zone.
  • the first zone and the second zone of the electrode of the bioelectrochemical cell system alternate position, such that the first zone of the electrode is completely immersed in the aqueous solution retained in the lower portion of the bioelectrochemical cell and the second zone of the electrode is completely remote from the aqueous solution.
  • the bioelectrochemical cell system of the present invention by providing for the first zone and the second zone of the electrode to alternate in position, alleviates the need for an ion exchange membrane or separator interposed between the first zone and the second zone of the electrode. Furthermore, the bioelectrochemical cell system of the invention may be operated without the mechanical recirculation of the aqueous solution, such as wastewater. The bioelectrochemical cell system of the present invention ameliorates the three economically significant problems described within the prior art.
  • the first zone and the second zone of the electrode of the bioelectrochemical cell system are adapted to be both anodic and cathodic.
  • the electrode of the present invention may be formed from any material that is conductive. In one form of the invention, the electrode is formed from material selected from the group: stainless steel, carbon fibre, graphite, granular graphite and combinations thereof.
  • the electrode is rotatably provided within the bioelectrochemical cell and the bioelectrochemical cell system further comprises a rotating means for rotating the electrode.
  • the rotating means may be located outside the bioelectrochemical cell or within the upper portion of the bioelectrochemical cell, such that when in use, the rotating means is above the level of aqueous solution present therein.
  • the electrode is rotatably provided within the bioelectrochemical cell and the bioelectrochemical cell system further comprises a rotating means for rotating the electrode such that, when in use, the first zone and the second zone rotate by 180°.
  • the bioelectrochemical cell system further comprises a biological support mounted to the electrode of the bioelectrochemical cell.
  • the biological support is adapted to support a biofilm.
  • a biofilm is provided on at least part of the biological support mounted to the electrode of the bioelectrochemical cell system, such that in use, the biofilm is adapted to subject the electrode to a polarization potential when the first zone or second zone of the electrode is at least partially immersed in an aqueous solution retained in the lower portion of the bioelectrochemical cell.
  • the electrode of the bioelectrochemical cell system when in use, is rotated such that a biofilm is established thereon and the electrode intermittently serves as the anode and the cathode alternately by rotation.
  • the use of biofilms in any of the preceding bioelectrochemical cell systems does not necessarily contribute to the improvement in the electrochemical rates at the electrodes, but to the biological production of electricity and/or gas by-products.
  • the bioelectrochemical cell system may further comprise an electrical circuit in communication with the electrode.
  • the bioelectrochemical cell system may further comprise a catalyst on the electrode.
  • the lower portion of the bioelectrochemical cell is adapted to contain micro-organisms, such that, in use, the micro-organisms catalyze transfer of electrons from the aqueous solution retained in the lower portion of the bioelectrochemical cell to the electrode, and to the circuit.
  • the upper portion is adapted to contain microorganisms such that, in use, the micro-organisms catalyze transfer of electrons from the electrode to an electron acceptor remote from the aqueous solution.
  • the bioelectrochemical cell system may contain microorganisms in the upper portion and the lower portion of the bioelectrochemical cell, such that, in use, the micro-organisms of the upper portion catalyze transfer of electrons from the electrode to an electron acceptor and the micro-organisms of the lower portion catalyze transfer of electrons from the aqueous solution retained in the lower portion of the bioelectrochemical cell to the electrode.
  • the bioelectrochemical cell system of the present invention may further comprise an electrical power supply electrically connected to the electrical circuit, wherein in use, voltage is applied from the electrical power supply between either the first zone or the second zone of the electrode, being the zone that is at least partially immersed, in the aqueous solution retained in the lower portion of the bioelectrochemical cell and the zone at least partially remote from the aqueous solution, such that the zone remote from the aqueous solution is cathodic, thereby promoting chemical synthesis and/or fermentation and/or biotransformation of the aqueous solution in the lower portion of the cell.
  • the bioelectrochemical cell system of the present invention provides for both nitrification and denitrification processes in the upper portion of the bioelectrochemical cell.
  • the upper portion of the bioelectrochemical cell may be oxygenated, aerated or open to the air, or alternatively enclosed.
  • the bioelectrochemical cell system of the present invention may also provide for conversion of nitrate or nitrite to nitrogen in the lower portion of the cell.
  • the bioelectrochemical cell system further comprises an inlet and an outlet, wherein in use, a quantity of the aqueous solution enters the bioelectrochemical cell through the inlet, and a quantity of the aqueous solution departs through the outlet.
  • the present invention further provides for a method for treating an aqueous solution, the method comprising the steps of: providing a quantity of an aqueous solution to a bioelectrochemical cell, the bioelectrochemical cell comprising an upper portion; a lower portion adapted to retain an aqueous solution; and an electrode, the electrode having a first zone and a second zone, wherein, the electrode is provided within the bioelectrochemical cell, the first zone and the second zone being in electrical communication; providing an electrical circuit in communication with the electrode; at least partially immersing the first zone of the electrode in the quantity of aqueous solution such that at least part of the second zone of the electrode is remote from the aqueous solution, wherein the first zone allows transfer of electrons released from the aqueous solution to the circuit and the second zone allows transfer of electrons from the circuit to the aqueous solution; after a predetermined period, at least partially alternating the first zone and the second zone of the electrode such that the second zone is at least partially immersed in the a
  • the method for treating an aqueous solution further comprises an electrical power supply in electrical connection with the first and the second zone of the electrode, wherein the method further comprises the step of enhancing an electrical potential between first and the second zone, such that the zone at least partially immersed in the aqueous solution is anodic and such that the zone at least partially remote from the aqueous solution is cathodic.
  • the enhancement of the electrical potential between first and the second zones of the embodiment may in turn enhance chemical synthesis and/or fermentation and/or biotransformation occurring in the aqueous solution contained within the cell.
  • the method comprises the step of connecting an electrical load to the electrical circuit, wherein an electrode zone, being the first or second zone, at least partially immersed in the aqueous solution is anodic and the bioelectrochemical cell generates electrical current detectable at the load.
  • the method of the present invention comprises the step of detecting the electrical current at the load.
  • the electrical current detected at the load may be used as a source of electricity.
  • the electrical current detected at the load may be measured in a chemical or biochemical sensing device.
  • the electrode is provided rotatably within the bioelectrochemical cell.
  • the electrode is provided with a biofilm mounted thereon.
  • the upper portion of bioelectrochemical cell is adapted to enable both nitrification and denitrification processes.
  • the lower portion is adapted to enable conversion of nitrate and/or nitrite to nitrogen.
  • the present invention further provides a method for generating gas by-products and electricity by treatment of an aqueous solution, the method comprising the steps of: providing a quantity of an aqueous solution to a bioelectrochemical cell, the bioelectrochemical cell comprising an upper portion; a lower portion adapted to retain an aqueous solution, the bioelectrochemical cell having a wall generally enclosing and defining an interior space adjacent an interior surface of the wall, and defining an exterior; and an electrode, the electrode having a first zone and a second zone, wherein, the electrode is provided within the cell, the first zone and the second zone being in electrical communication; providing an electrical circuit in communication with the electrode; providing micro-organisms to the bioelectrochemical cell, wherein the aqueous solution is oxidizable by an oxidizing activity of the micro-organisms; at least partially immersing the first zone of the electrode in the aqueous solution such that at least part of the second zone of the electrode is remote
  • the bacteria provided to the bioelectrochemichal cell are anodophilic bacteria.
  • the anodophilic bacteria are adapted to generate methane or hydrogen gas.
  • the method for generating gas by-products and electricity by treatment of an aqueous solution may further comprise the step of rotatably providing the electrode to the bioelectrochemical cell.
  • the method of the present invention further comprises a biofilm mounted on the rotatably provided electrode.
  • the upper portion is adapted to enable both nitrification and denitrification processes and the lower portion is adapted to enable conversion of nitrate and/or nitrite to nitrogen.
  • the method for generating gas by-products and electricity during treatment of an aqueous solution further comprises a biofilm mounted on the cathodic zone of the electrode, such that the cathodic zone of the electrode is a biocathode, and the catalytic effect of the biofilm and the energy value of the gas by-product allows for a more energy efficient cathode, compared to a traditional oxygen-cathode.
  • the bioelectrochemical cell system of the present invention may operate as a microbial fuel cell, producing electricity from organic pollutants, without the poor cathodic reaction of oxygen reduction; and a build-up of a pH gradient between an anode and a cathode over time, which leads to a reduction in the activity of electrochemically active bacteria.
  • the bioelectrochemical cell system of the invention may use electrical energy as a source of reducing power in chemical, fermentation or biotransformation reactions and may use aqueous solutions, such as wastewater as electron mediators and a catalyst, to produce electricity and/or gas by-products.
  • Various catalysts are suitable for use in the bioelectrochemical cell system in accordance with the invention.
  • the catalyst may comprise an oxidoreductase (e.g., fumarate reductase) bound to the electrode.
  • the catalyst may also comprise bacterial cells disposed in the lower portion of the cell.
  • Non- limiting examples of bacterial cells include cells of Actinobacillus succinogenes, cells of Escherichia coli, and sewage sludge.
  • the bioelectrochemical cell system of the present invention does not require ionic exchange membranes to separate the anode and cathode.
  • the electrode zones of the present invention may act as both an anode and a cathode, whereby alternating electrode zones results in polarity inversion on both the first and second zones of the electrode, leading to increasing pollutant removal rate.
  • pumps are used to achieve aqueous solution flow in the present invention and the establishment of anodophilic/ cathodophilic biofilm
  • the aqueous solution employed any of the preceding methods is preferably an aqueous solution product from agricultural, mining (alumina, gold, nickel processing), food processing or beverage (brewing and winery) production industries.
  • the aqueous solution is wastewater.
  • the following description expounds on the invention in terms of its use in the treatment of wastewater.
  • the invention is not however limited only in this context. A person of skill reading this application will and should recognise and understand that a wide varieties of liquids may be employed in the method of the invention without departing from the employed methodology.
  • wastewater refers to a mixture of water and dissolved or suspended solids. It is generally water, derived from residential, business or industrial sources, which may contain a variety of waste products such as soap, chemicals or manure. It may be derived from a wide variety of sources, for example effluent from agricultural sources such as animal farming practices including piggeries, aquaculture sources, poultry farms and dairy farms. Industrial wastewater and effluent from sources such as paper and pulp mills, sugar refineries, abattoirs, food processing and manufacturing industries, effluent from the tanning industry, the defence industry (e.g. munitions production), the food industry, the agriculture industry, the chemical industry (e.g. manufacturing of fertilizers) and mining may be treated using the present method.
  • agricultural sources such as animal farming practices including piggeries, aquaculture sources, poultry farms and dairy farms.
  • Industrial wastewater and effluent from sources such as paper and pulp mills, sugar refineries, abattoirs, food processing and manufacturing industries, effluent from the tanning industry, the defence industry (e
  • wastewater to be treated using the method of the present invention is wastewater derived from a municipal wastewater treatment facility, such as sewage. It is contemplated that the methods of the present invention are suitable for removal of nitrogenous matter, carbonaceous matter, matter containing phosphate, and/or mixtures thereof from aqueous waste generated by, for example, domestic, agricultural, mining or industrial processes.
  • Wastewater can also include natural or modified water bodies such as aquifers, lakes, ponds, pools, lagoons, rivers or run-offs and leachates from material that is in contact with water, as long as it contains ammonia, or other nitrogen substances and organic compounds.
  • natural or modified water bodies such as aquifers, lakes, ponds, pools, lagoons, rivers or run-offs and leachates from material that is in contact with water, as long as it contains ammonia, or other nitrogen substances and organic compounds.
  • biofilm employed by the present invention, is a structured community of microorganisms encapsulated within a self-developed polymeric matrix and adherent to a living or inert surface.
  • Biofilm based bioelectrochemical cell may increase the biomass 'concentration' compared to a similar sized suspended culture reactor and hence may have lower footprint requirements. This is of particular interest with increasingly dense urban populations, as the volume of wastewater to be treated is high while the land available for treatment is low.
  • Biofilms may also assist in the regulation of population characteristics, for example, the maintenance of a high level of nitrifiers without sludge bulking.
  • the use of biofilms may also reduce the amount of wastewater liquor which is retained in suspended culture aerobic nitrifying reactors and is therefore not available to be denitrified.
  • the use of a biofilms may also eliminate the need for settling and clarification of treated wastewater.
  • the biomass may be composed of any population of micro-organisms that are able to perform denitrification of the wastewater being treated, i.e. the conversion of oxidised nitrogen to a gaseous end product and that are able to convert ammonia to nitrate.
  • the biomass may be composed of microbes such as bacteria, fungi and archaea.
  • the biomass is composed principally of bacteria.
  • any microbe that is capable of denitrifying wastewater may be used.
  • Figure 1 is a schematic diagram of an electrode disc set according to the present invention. with an o-ring and a small extension of the stainless steel mesh.
  • Figure 2 is a schematic diagram of a batch bioelectrochemical cell system according to the present invention operated for electricity generation.
  • Figure 3 is a schematic diagram of an alternate batch bioelectrochemical cell system according to the present invention operated for electricity generation.
  • Figure 4 is a schematic diagram of an alternate batch bioelectrochemical cell system according to the present invention operated for electricity generation.
  • Figure 5 is a schematic diagram of an alternate batch bioelectrochemical cell system according to the present invention coupled with a potentiostat for enhanced cathodic oxygen reductions at a chemostat mode operated to overcome the thermodynamic constraint of the poor cathodic oxygen reduction.
  • FIG 2 there is shown a bioelectrochemical cell system for treating an aqueous solution in accordance with a first embodiment of the present invention.
  • the bioelectrochemical cell (cell) 10 comprises a vessel 9, provided with an inlet and an outlet (not shown).
  • the cell 10 comprises an upper portion 11 ; a lower portion 12 adapted to retain an aqueous solution; and a plurality of electrodes 30 provided within the cell.
  • each of the electrodes 30 comprises a first zone 31 and a second zone 32.
  • each of the electrodes is provided in the form of a rotatable electrode disc assembly comprising at least one disc.
  • Figure 1 further shows the rotatable electrode disc 30 consisting of two zones, being a first zone 31 and a second zone 32.
  • Each of the first and second zones 31 and 32 consists of a stainless steel current collecting mesh 35. Electrically conductive carbon fibre sheet is mounted onto both sides of the mesh.
  • the first zone 31 and the second zone 32 are separated by a central shaft 34 and an O-ring 33.
  • the first and second zones 31 and 32 are in electrical communication via the stainless steel mesh 35,.
  • the vessel 9 of the first embodiment comprises a cylindrical Perspex transparent water pipe (298 mm length; 140 mm diameter) with its two ends covered by two separate square Perspex side plates 13 (160 x 160 mm). A rubber O-ring is located between each side plate and the centre pipe to assure air and water tightness.
  • the rotatable electrode disc assembly 34 comprises a Perspex horizontal central rotatable shaft 36 (see Figure 1). Two separate stainless steel current collecting strips are independently mounted onto the upper and lower sides of the shaft (not shown). As illustrated, in the first embodiment, 20 sets of rotatable electrode discs 30 are mounted onto the central rotatable shaft 36 (see Figure 2).
  • a Perspex plastic o-ring is used to connect each pair of electrode discs 30 with the central shaft 36 and to maintain a constant distance with the neighbouring discs.
  • the estimated total projected surface area (immersed in an aqueous solution) of the 20 disc halves is 947 cm 2 . This value is used for calculating the current and power densities.
  • the total working volume of the cell is used to calculate acetate or COD removal rates and hydraulic retention time of the system when operated at continuous mode.
  • the system does not require the use of a membrane or separator.
  • the electrical circuit 14 in electrical communication with the electrode zones 31 and 32; therefore electrical energy is generated if a suitable resistive load is located between the two zones 31 and 32 of the electrode 30.
  • the reference electrode 15 allows the potential of the cell to be determined.
  • Figure 3 illustrates a second embodiment of the present invention, comprising a stepper motor unit 16 consisting of a stepper motor, a stepper motor driver, and an analog output card is mounted onto the side plate of the cell.
  • a gear disc one-to-seven reduction
  • the stepper motor 16 and its driver is calibrated such that upon receiving a proper signal from the analog output card (such as LabjackTM), the central rotatable electrode disc assembly can be precisely rotated for a fixed degree (e.g. full turn, 360°; half turn, 180°, etc) at predetermined time intervals.
  • the first zone of the electrode 32 can rotate from being at least partially immersed in an aqueous solution retained in the lower portion of the cell 10 such that the first zone is anodic, to being at least partially remote from the aqueous solution such that, the zone 32 is cathodic.
  • the second zone of the electrode 31 can rotate from being at least partially remote from the aqueous solution such that, the zone is cathodic, to being at least partially immersed in an aqueous solution retained in the lower portion of the cell 10 such that the second zone 31 is anodic.
  • a computer program 17, such as LabVIEWTM (version 7.1 National Instrument) can be used to control and monitor the cell, for example, the program can be used to control the alternating of the electrodes 30, as illustrated in a third embodiment of the present invention (see Figure 4).
  • the computer program LabVIEWTM can be used to increase voltage to achieve fixed anodic and cathode potentials, record current, cell voltage, anodic potential and cathodic potential, record dissolved oxygen, record hydrogen gas production and record the pH of the cell.
  • the cathodic reaction can be enhanced upon providing additional voltage to the system.
  • a potentiostat 20 can be used to provide extra power supply for the system, as illustrated in Figure 5, thereby avoiding the thermodynamic constraint of the poor cathodic oxygen reduction and allowing higher anodic potential.
  • the working (41), counter (42) and reference electrodes (43) of the potentiostat 20 are connected to the at least partially immersed in an aqueous solution first electrode zone 32, the at least partially remote from the aqueous solution second electrode zone 31 and the reference electrode 15, respectively.
  • the first zone of the electrode 32 can rotate from being at least partially immersed in an aqueous solution retained in the lower portion of the cell 10 such that the first zone is anodic, to being at least partially remote from the aqueous solution such that, the zone 32 is cathodic.
  • the second zone of the electrode 31 can rotate from being at least partially remote from the aqueous solution such that, the zone is cathodic, to being at least partially immersed in an aqueous solution retained in the lower portion of the cell 10 such that the second zone 31 is anodic.
  • a computer 17 controllable relay switch 25 can be used to synchronize the control by the potentiostat 20, such that whichever electrode is at least partially immersed in an aqueous solution retained in the lower portion of the cell 10 can always act as the working anodic electrode, while the electrode at least partially remote from the aqueous solution always act as the counter cathodic electrode.
  • a wastewater treatment apparatus In a further embodiment of this invention describes a wastewater treatment apparatus. Specifically, it describes the conversion of organic matters in wastewaters into a form of energy, such as electricity or gas by-products. Further, it describes an anoxic reactor through which wastewater which has previously been nitrified may be denitrified. It is not intended that these embodiments be limiting, as other anoxic, anaerobic and aerobic processes in which a microorganism is provided with a reciprocating biofilm support in order to encourage a biological reaction through the apparatus described in this document are intended to fall within the disclosure of the invention.
  • a return activated sludge collected from domestic wastewater treatment plant was used as the initial inoculums. It was stored at 4°C prior use.
  • a synthetic wastewater used consisted of (mg L '1 ): NH 4 CI 125, NaHCO 3 125, MgSO 4 TH 2 O 51 , CaC
  • L “1 of trace element solution which contained (g L "1 ): ethylene-diamine tetra-acetic acid (EDTA) 15, ZnSO 4 -7H 2 O 0.43, CoCi 2 -6H 2 0 0.24, MnC, 2 -4H 2 O 0.99, CuSO 4 SH 2 O 0.25, NaMoO 4 -2H 2 O 0.22, NiCI 2 GH 2 O 0.19, NaSeO 4 -IOH 2 O 0.21 , H 3 BO 4 0.014, and 0.050.
  • Yeast extract (0.1-1 g L "1 279 final concentration) was added as bacterial growth supplement. Unless otherwise stated, the initial pH of the synthetic wastewater was adjusted to 6.9-7.2 using either 1 M HCI or 4M NaOH.
  • Electrode potential (mV) herein refers to values against Ag/AgCI reference electrode (ca. +197 mV vs. standard hydrogen electrode).
  • the bioelectrochemical cells were inoculated with synthetic wastewater containing 10% (v/v) of a return activated sludge collected from a local municipal wastewater treatment plant. The initial two months, the cells were operated in batch mode. A variable external resistor (5 - 1 M ohm) was used to connect the first zone and the second zone of the electrode. The cells were operated at ambient room temperature (22 - 25° C) and atmospheric pressure. Polarization curve analysis was performed regularly to evaluate performance over time. The analysis was done by decreasing the external resistance of the cell from 1 M to 5 ohm in a stepwise manner. For each external resistance setting, at least 5 min waiting period was given to obtain steady state values of current (I) and voltage (V).
  • I current
  • V voltage
  • Example 1 Cathodic Oxygen Reduction Using an External Power Supply
  • a potentiostat was used to provide extra power supply for the process.
  • the working, counter and reference electrodes of the potentiostat were connected to the immersed electrode zone, the aqueous solution remote zone of the electrode and the reference electrode, respectively.
  • the electrode zones would be alternated regularly between the aqueous solution in the lower portion of the cell and the upper portion of the cell, at least partially remote from the aqueous solution, the electrode zones would serve alternately as an anode and cathode
  • a computer controllable relay switch was used to synchronize the control by the potentiostat. Such that whichever electrode zone that was immersed in the aqueous solution could always act as the working electrode (anode) while the air-exposed discs always act as the counter electrode (cathode).
  • the biofilm electrodes collected under these two conditions were examined by using scanning electron microscopy (SEM) (Philips XL 20 Scanning Electron Microscope). At appropriate time points as specified in the article, a small piece of carbon sheet was cut with a sterile stainless steel scissor. The electrode samples were fixed in 3 % glutaraldehyde in 0.025 M phosphate buffer (pH 7.0), overnight at 4 0 C C.
  • SEM scanning electron microscopy
  • the samples were then rinsed three times (5 min each time) with 0.025 M phosphate buffer (pH 7.0) before they were subjected to dehydration procedure through a series of ethanol solution (each solution was changed two times and each change was 15 min): 30, 50, 70, 90 and 100%. The 100% ethanol solution was replaced with amyl acetate (two changes, 15 min each).
  • the samples were critical point dried before they were mounted to SEM specimen holder with contact adhesive. The samples were then sputter coated with gold before being subjected to SEM observation. Abiotic plain carbon sheet were treated with the same procedures and served as the Control.
  • the proposed cell allows electricity generation using activated sludge as the bacterial catalyst.
  • Example 5 Increased Anodophilic Activity increases Current and Power Output
  • the improvement of current and power output of the bioelectrochemical cell can be due to an improved anodophilic activity of the biofilm over time.
  • Anodophilic activity of biofilms can be visualized from a plot of current versus anodic potential (Cheng et al., 2008).
  • improved anodophilic activity is indicated by an increase of current without a significant polarization of the biofilm-anode (i.e. anodic potential becomes more positive).
  • the results indicate anode polarization was decreased over time. For instance, an increase of current density from the lowest to the highest point (by decreasing the external resistance) resulted in an anode polarization of +244 mV (i.e.
  • acetate concentrations were monitored over a batch cycle with two external resistance settings (2 ohm and 1M ohm). During the batch, the discs were rotated once every 15 min.
  • the aqueous solution immersed anodic electrode zone potentials in both resistance settings decreased from -50 mV to about -490 mV.
  • Current generation was negligible at 1M ohm. While at 2 ohm, acetate addition could immediately increase the current from 0.18 to 3.4 mA within an hour. Thereafter, a gradual, linear increase of current was observed until a maximal level of 5.8 mA was reached at 12.3 h. Upon acetate depletion, the current decreased to its background level.
  • the electrode discs were flipped (180 °) once per hour, such that the electrode zones alternated between acting as an anode partially immersed in the aqueous solution and a cathode, at least partially remote from the aqueous solution.
  • the hourly flipping of the electrode discs at 2 ohm could reverse the current (ranged from -6.7 to +7.5 mA), indicating that a biofilm could alternately catalyze the current under alternating anodic- cathodic conditions.
  • Example 8 Electrochemically Assisted Anode Facilitates the Establishment of
  • the potential of the submerged anode disc was controlled by the potentiostat at -300 mV. In the absence of acetate, a background current of less than 3 mA was observed. Acetate addition immediately increased the current to about 40 mA within 15 min. Thereafter, the current was continuously increased to a maximal level of about 60 mA within lOhours. Acetate depletion resulted in a gradual decline of current to its original level. The maximal current was ranged from 60 to 70 mA. It was about 10 times higher than that previously obtained.
  • the COD removal rate obtained from the bioelectrochemical cell fall within the range of the conventional AS processes, indicating that the bioelectrochemical cell process is equally good as compared to the AS processes in removing organic pollutants from the wastewater.
  • the bioelectrochemical cell process demonstrated better efficiency (0.47 kWh kg COD '1 ) compared to the AS processes (0.7 to 2 kWh kg COD "1 ).
  • the bioelectrochemical cell process also demonstrated at least 5 times less energy demand per volume of wastewater treated as compared to the AS processes (88 vs. 430 kWh ML "1 ) (Table 1).
  • Table 1 Treatment performance and energy requirement of the bioelectrochemical cell process and conventional activated sludge (AS) processes.
  • the values include the energy consumption by the stepper motor (0.083 Wh per one rotation).
  • Applications of the present invention may vary in size from commercial plants to personal use units for example, for use on a small boat.

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Abstract

L'invention concerne un système de pile bio-électrochimique qui comprend une partie supérieure, une partie inférieure adaptée pour contenir une solution aqueuse et une électrode, laquelle présente une première zone et une deuxième zone, l'électrode étant prévue à l'intérieur de la pile bio-électrochimique, la première zone et la deuxième zone de l'électrode étant en communication électrique et, lors de son fonctionnement, la première zone de l'électrode étant au moins partiellement immergée dans une solution aqueuse que contient la partie inférieure de la pile bio-électrochimique, de telle sorte que la première zone est anodique, au moins une partie de la deuxième zone de l'électrode étant située à distance de la solution aqueuse, de telle sorte que la deuxième zone est cathodique.
PCT/AU2010/000959 2009-07-29 2010-07-29 Système de pile bio-électrochimique Ceased WO2011011829A1 (fr)

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Cited By (9)

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CN103073114A (zh) * 2013-02-06 2013-05-01 哈尔滨工程大学 一种低处理成本的废水脱色方法
KR101417610B1 (ko) 2013-03-22 2014-07-10 송영채 분리막에 수직으로 설치된 3차원 공기환원전극을 구비한 생물전기화학전지
JP2017504146A (ja) * 2013-11-22 2017-02-02 カンブリアン イノベーション インク．Ｃａｍｂｒｉａｎ Ｉｎｎｏｖａｔｉｏｎ Ｉｎｃ． コスト効果の高い生物電気化学システムのための電極
US10340545B2 (en) 2015-11-11 2019-07-02 Bioenergysp, Inc. Method and apparatus for converting chemical energy stored in wastewater into electrical energy
US10347932B2 (en) 2015-11-11 2019-07-09 Bioenergysp, Inc. Method and apparatus for converting chemical energy stored in wastewater
DE102019002037A1 (de) * 2019-03-22 2020-10-08 Robert Bunderla Vorrichtung zur Erzeugung elektrischer Energie
US20220135929A1 (en) * 2020-10-29 2022-05-05 Tongji University Apparatus and method for enhancing anaerobic digestion based on the coupling of electron transfer with microbial electrolytic cell
US12304844B2 (en) * 2017-10-25 2025-05-20 Advanced Environmental Technologies, Llc Method for advanced bioelectrochemical treatment of pollutants
US20250262655A1 (en) * 2024-08-09 2025-08-21 Tongji University Integrated system for anaerobic digestion of organic solid waste

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US20060011491A1 (en) * 2004-07-14 2006-01-19 Bruce Logan Bio-electrochemically assisted microbial reactor that generates hydrogen gas and methods of generating hydrogen gas
WO2008059331A2 (fr) * 2006-10-03 2008-05-22 Power Knowledge Limited Réacteur bioélectrochimique
WO2008133742A2 (fr) * 2006-12-06 2008-11-06 Musc Foundation For Research Development Appareils et méthodes de production d'éthanol, d'hydrogène et d'électricité
US20080292912A1 (en) * 2006-05-02 2008-11-27 The Penn State Research Foundation Electrodes and methods for microbial fuel cells

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US20060011491A1 (en) * 2004-07-14 2006-01-19 Bruce Logan Bio-electrochemically assisted microbial reactor that generates hydrogen gas and methods of generating hydrogen gas
US20080292912A1 (en) * 2006-05-02 2008-11-27 The Penn State Research Foundation Electrodes and methods for microbial fuel cells
WO2008059331A2 (fr) * 2006-10-03 2008-05-22 Power Knowledge Limited Réacteur bioélectrochimique
WO2008133742A2 (fr) * 2006-12-06 2008-11-06 Musc Foundation For Research Development Appareils et méthodes de production d'éthanol, d'hydrogène et d'électricité

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103073114A (zh) * 2013-02-06 2013-05-01 哈尔滨工程大学 一种低处理成本的废水脱色方法
KR101417610B1 (ko) 2013-03-22 2014-07-10 송영채 분리막에 수직으로 설치된 3차원 공기환원전극을 구비한 생물전기화학전지
JP2017504146A (ja) * 2013-11-22 2017-02-02 カンブリアン イノベーション インク．Ｃａｍｂｒｉａｎ Ｉｎｎｏｖａｔｉｏｎ Ｉｎｃ． コスト効果の高い生物電気化学システムのための電極
US10340545B2 (en) 2015-11-11 2019-07-02 Bioenergysp, Inc. Method and apparatus for converting chemical energy stored in wastewater into electrical energy
US10347932B2 (en) 2015-11-11 2019-07-09 Bioenergysp, Inc. Method and apparatus for converting chemical energy stored in wastewater
US12304844B2 (en) * 2017-10-25 2025-05-20 Advanced Environmental Technologies, Llc Method for advanced bioelectrochemical treatment of pollutants
DE102019002037A1 (de) * 2019-03-22 2020-10-08 Robert Bunderla Vorrichtung zur Erzeugung elektrischer Energie
DE102019002037B4 (de) 2019-03-22 2021-12-09 Robert Bunderla Verfahren und Vorrichtung zur Erzeugung elektrischer Energie
US20220135929A1 (en) * 2020-10-29 2022-05-05 Tongji University Apparatus and method for enhancing anaerobic digestion based on the coupling of electron transfer with microbial electrolytic cell
US20250262655A1 (en) * 2024-08-09 2025-08-21 Tongji University Integrated system for anaerobic digestion of organic solid waste

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