WO2013167107A1

WO2013167107A1 - Device and method for bioelectrochemical material conversion (inducing a reduction/oxidation/redox reaction)

Info

Publication number: WO2013167107A1
Application number: PCT/DE2013/000247
Authority: WO
Inventors: Florian Pfeiffer
Original assignee: Florian Pfeiffer
Priority date: 2012-05-07
Filing date: 2013-05-06
Publication date: 2013-11-14
Also published as: DE102013007659A1; DE112013002364A5

Abstract

The invention relates to a device (1) for bioelectrochemical material conversion of organic and/or inorganic materials in an aqueous and/or gaseous state, comprising at least one inlet (5, 14, 19, 20) and at least one outlet (9, 15, 21, 22). The invention also relates to a method for operating the device (1), wherein at least one anode (2) and/or at least one cathode (3) is arranged in at least one reactor (6, 8, 13, 17, 18), wherein by means of the at least one inlet (5, 14, 19, 20) educts are fed to the at least one reactor (6, 8, 13, 17, 18) and are there bioelectrochemically converted or reacted by means of the at least one anode (2) and/or the at least one cathode (3).

Description

Apparatus and method for bioelectrochemical conversion (inducing a reduction / oxidation / redox reaction)

State of the art

The invention is based on a device for bioelectrochemical conversion according to the preamble of claim 1 and a method for operating the device according to the preamble of claim 13.

In the known devices and methods for the conversion of ingredients in fluids and also partially in gases that are not in thermodynamic equilibrium with their environment or have a redox potential, biological purification process, in particular for clarification of wastewater, as the most cost-effective method and thereby established in the general application. The disadvantages of these biological processes, here aerobic and anaerobic processes, for example, known from wastewater treatment or energy, such. As the patents AT 265152 and AT 81 109 E, are a high energy input, a low energy yield, a partially high excess sludge production, a limited substrate spectrum and partially limited efficiencies. The well-known chemical-physical processes, such as the patent DD 244 743 AI, usually have even higher costs and an even more expensive energy. In addition, the components / parameters involved there are often not implemented, but merely separated and concentrated.

In the likewise known ion elimination by means of electrolysis, also a material-converting process, a very high energy consumption is required, whereby the practical use in the applications is very limited.

In addition, bioelectrochemical processes are already known, such as the closest prior art disclosed in International Patent Application WO2011 / 006939. In this document, a three-stage process for the bioelectrochemical wastewater treatment of nitrogen compounds is shown. In the first stage, a half element is arranged with an anode for the conversion of hydrocarbon compounds. The second stage is formed from an aerobic reactor and in the third stage a half-element is arranged with a cathode for denitrification. A disadvantage of this technical solution is that in this case a large expenditure on equipment is necessary and on the other hand, due to the aerobic reactor stage, higher costs and higher excess sludge are produced.

Disadvantages of the prior art

Aerobic biological processes achieve high efficiencies during purification, since oxygen (or air) is blown in until the processing substrate has been oxidized relatively completely. This is with the Disadvantage of a high sludge production and high additional energy requirements. The high efficiencies in the aerobic process are based on the simple technical apparatuses and means used there, via which oxygen (O 2) is provided in sufficient quantity as a terminal electron receptor for the aerobic processes. The use of oxygen, however, produces a great deal of excess sludge, which must be post-treated relatively expensive following the aerobic process. In any case, this technology is itself very energy-intensive (see "Römpp-Lexikon, Biotechnology aerobic wastewater treatment).

In contrast to the aerobic process, excess sludge production is significantly lower in anaerobic processes. However, this is associated with the disadvantage that the methods are limited in their efficiency, since the substances involved are not available indefinitely, or since, by definition, oxygen is not oxidized here (and therefore no electrons can be released "to the outside"). The energy input to be made here is also limited since the energy only has to be expended for the mixing of the substrate, with the additional disadvantage of processes with an additional heat requirement.

Depending on the process and the desired effect, the two processes, namely for the reduction or elimination of nitrogen on an aerobic or anaerobic basis, can be combined with one another. However, such a combination of methods requires additional energy, for example, for the necessary recirculation. Moreover, both methods are limited in their substrate spectrum. In the anoxic intermediate region, the energy input as well as the efficiencies due to the substrate distribution is limited. Both methods are thus limited either in the substrate spectrum (for example, metered addition of an external carbon source) or in the synthesis production.

Bioelectrochemical denitrification has many advantages as well as in combination with the above techniques. The achievable efficiencies are comparable to the oxidation, as the anode can perform this function without producing the increased excess sludge accumulation. The cathode can take over the function of the electron donor, whereby a possible substrate restriction in the offer can no longer have a limiting effect on the cleaning performance.

The electrolysis has high efficiencies with a low sludge production and a broad substrate spectrum, but requires a lot of energy to overcome the cell and ion voltage. In addition, the inorganic catalyst consumes during the electrolysis. A mixed process with microbial fuel cell has never become marketable, due to the expensive arrangements. In many cases, the systems have been optimized for direct energy generation instead of relying on material conversion as a basic process.

The bioelectrochemical denitrification also has many advantages in combination with the above process techniques, since oxidation, or reduction, or a redox reaction can be brought about at a specific site and with great independence. The underlying task of the invention

The invention has for its object to develop a method and a device for cleaning the contaminant load in a substrate such as sewage, manure, biogas plants and the like. With reduced energy input and possibly energy surplus, or synthesis product production (eg biogas). The method should be combinable with conventional methods in order to optimize them. It is the surplus sludge balance to be improved while reducing the operating costs. In addition, the process should have a higher efficiency, as well as a broader substrate spectrum.

The invention and its advantages

The device according to the invention for the bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous state with at least one inlet and at least one sequence with the characterizing features of claim 1, and the inventive method for operating the device, with the characterizing features of the claim 13, in contrast, have the advantage that at least one anode and / or at least one cathode is arranged in at least one reactor, wherein educts are fed to the at least one reactor by means of the at least one inlet and there by means of the at least one anode and / or the at least one cathode be converted or converted bioelectrochemically. As a result, the expenditure on equipment is reduced in comparison to the previously known methods. In addition, the process works membraneless and is thus suitable for both batch and continuous operation, whereby it is irrelevant whether it is a special (aggressive) or moderate environment environment.

According to an advantageous embodiment of the device according to the invention, a biofilm is applied to the at least one anode and / or at least one cathode. Attaching the biomass to the electrodes catalyses the process that is going on. Due to this reduced cell voltage and the energy expenditure is comparatively very low and it must be overcome only the cell voltage of the bacterial mass involved. For this purpose, a low potential is applied from the outside, such as the potentiostat. Thus, the process becomes a low load process. On the one hand, because of the thermodynamic situation of the underlying redox reactions, an excess of the electron can be achieved or, on the other hand, any deficiency for a particular reaction with additional electrons can be compensated. According to the invention, it is possible to carry out, carry out or separate from one another reduction or oxidation, or to allow redox reactions between partners whose redox potential otherwise would not be accessible (for example, direct anaerobic ammonium elimination without formation of NO 2, NO 3). ,

Compared to previous known methods, such as electrolysis, but the process proceeds with significantly reduced voltage, since not the process of forced ion discharge is based, but the redox reaction is biologically catalyzed with direct electron transfer.

According to an advantageous embodiment of the device according to the invention, the biofilm on the at least one anode and / or the at least one cathode is a sessile biofilm. Thus, follows a direct electron uptake and -abgäbe by means of the catalyzing biomass, whereby the usually very large concentration gradient between the fixed at least one electrode biofilm and the surrounding substrate is reduced. Process catalysing sessile biofilm produces less excess sludge. Furthermore, due to the omission of the introduction of elemental oxygen as the terminal electron acceptor, a further reduction of the excess sludge production takes place (see Anaerobic Technique).

According to an additional advantageous embodiment of the device according to the invention, an electrical conductor is arranged on the at least one anode and / or the at least one cathode for electron transport. By virtue of this arrangement, the electrons received at the at least one anode or the electrons emitted at the at least one cathode can be removed or supplied to the process. Thus, it is possible to supply the electrons accumulating at the at least one anode to other consumers as a generated current. The arrangement thus additionally serves as a power source.

According to an additional advantageous embodiment of the device according to the invention, an electrical conductor is arranged between the at least one anode and the at least one cathode for electron transport. By coupling the at least one anode and the at least one cathode, the electrons released at the at least one anode can be dissipated directly to the at least one cathode. Thus, an external electron donor is not necessary. According to an additional advantageous embodiment of the device according to the invention, the device has a material line for the proton transport between the at least one anode and / or the at least one cathode. The proton transport takes place with the substrate, the electron transport via an electrical conductor. The method allows the involved redox partners to deliver the electrons directly from cell to cell. As a result, advantageously less or no energy is consumed in the process flow for any intermediate steps. Less energy is spent on maintaining cell activity (metabolism), so there is more energy available for other tasks or even energy surplus. Under otherwise identical conditions, the available potential of the substrate can therefore be used more effectively or the efficiency is subject u. U. no longer a restriction by otherwise lacking substrate supply (example: C / N ratio).

According to an additional advantageous embodiment of the device according to the invention, the material line for proton transport is a salt bridge or the like.

According to an additional advantageous embodiment of the device according to the invention several reactors are present, which are connected as a cascade. The arrangement of several reactors connected in series has the advantage that the wastewater to be clarified can be treated with its contaminant load in different stages and thus all individual reactor stages can be preconfigured specifically for the contaminated load (utilization of a concentration gradient). According to an additional advantageous embodiment of the device according to the invention, a balance of the bioelectrochemical equilibrium takes place by means of external energy intervention. Thus, the equilibrium of the reaction can always be adjusted so that the desired reactions proceed preferentially.

According to an additional advantageous embodiment of the device according to the invention, the at least one anode and / or the at least one cathode cause a mixing of the at least one reactor. The at least one anode and / or the at least one cathode are in this case designed as an agitator for the at least one reactor. The half elements embodied as stirrers may in this case, for example, take the form of an immersion body, or of an anchor, an inclined blade, a blade or a cross-bar stirrer. In addition, the flow baffles known in the prior art can also be used for improved mixing. By stirring the wastewater with its pollution load is always ideally mixed and the desired

Processes can run optimally.

According to an additional advantageous embodiment of the device according to the invention, the device is controlled by a controller. This has the advantage that the entire process can be monitored and regulated in terms of control technology and thus always the optimum process parameters prevail.

According to a related advantageous embodiment of the device according to the invention, the control is carried out by means of online measurement technology. Through the use of online or inline measurement, the current process parameters available for process control. This makes the process optimally controllable.

According to an advantageous embodiment of the method according to the invention for the bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous ZuStands with at least one inlet and at least one outlet, wherein by means of at least one feed educts are fed to at least one reactor and there by means of at least one Anode and / or at least one cathode are converted bioelectrochemically, the at least one anode and / or the at least one cathode are exposed to a changing environment in one phase. Advantageous is the possibility of spatial separation of electron donor and acceptor, with potential savings in any feedback or with additional degrees of freedom in the adjustment of environmental conditions, in the sole oxidation or reduction, or in the purification of two different streams.

Here, the electrode material is not subject to increased wear by triggering individual elements to catalyze reactions. The electrode material must only be conductive and have no biologically inhibiting or toxic effect. As electrode materials are, inter alia, steel, commercial V2A / V4A stainless steel, high-quality alloys, carbon-doped compounds, conductive plastic, graphite, carbon, conductive textiles and other artificial structures (eg fleece) in question. Depending on the desired reaction and the substrate present, for example, but not exclusively, inorganic or organic contaminant load can be converted. For example, in wastewater treatment or biogas production. Process conditions can be created that Transference reactions, such as methanogenesis or acetogenesis. With an appropriate adjustment of the environment and optionally of the substrate, elemental hydrogen can also be produced during the process. In principle, since the process only allows for electron donation and absorption, inorganic substrate is also treatable. For this, the substrate must not be inhibitory or toxic. Substrate with inorganic carbon is sufficient for cell structure ("Arche bacteria", "autotrophic bacteria"). Optionally, a correction of the CO 2 value depending on the purpose is necessary or even desirable. If necessary, a correction of the pH value depending on the application is necessary.

According to an additional advantageous embodiment of the method according to the invention, the device used for the bioelectrochemical conversion is a device according to one of claims 1 to 12.

Because of these features, significantly improved redox reactions take place in the device and in the method for the bioelectrochemical conversion of a solid or gaseous substrate on the electrode surfaces of the microbial fuel cell exposed to the substrate.

Further advantages and advantageous embodiments of the invention are the following description, the drawings and claims removed. drawing

Preferred embodiments of the subject invention are illustrated in the drawings and will be explained in more detail below. Show it

1 shows an arrangement of the device according to the invention,

Fig. 2 shows an additional arrangement of the invention

Device with only one reactor and one electrode and

Fig. 3 shows a further arrangement of the device according to the invention.

Description of the embodiments

In Fig. 1, an arrangement of the device 1 according to the invention is illustrated using an exemplary embodiment and described below. The arrangement shown in Fig. 1 for bioelectrochemical material conversion consists of a rotatable anode 2 and a rotatable cathode 3, wherein both the anode and the cathode electrode surfaces 4 have. A half-element (anode 2 or cathode 3) may consist of different partial surfaces due to the design. Due to the rotatability of the half-elements, the electrodes are used as stirrers as in an agitator and thus thorough mixing of the substrate is achieved. The individual partial surfaces are then correspondingly conductively connected with each other or are in direct contact with each other. According to the invention, a biofilm, in particular a sessile biofilm, which serves as catalyst in the process, is arranged on at least one of the electrode surfaces 4 of the two half-elements. A coating of Electrode surfaces 4 with the biofilm may optionally be made in advance or directly over the substrate. Usually, the biofilm, also called biomass, ubiquitous, so it is in the substrate, which in a sewage treatment plant, for example, represents the wastewater to be purified including the pollution load, where the material conversion is to take place, and does not have to be from outside to or tracked. In addition, the substrate can be inoculated in special cases but also from the outside with biomass, which may be bacteria, for example. The substrate is transported via the inlet 5 into the reactor 6 and from there by means of a material line 7 into the reactor 8 and leaves it via the outlet 9 purified the process. The material line 7 may also be a salt bridge or the like., And serves the proton transport in the inventive arrangement. The biofilm lowers the concentration gradient at both the anode and the cathode, making the process a low load process, that is, a small cell voltage 10 can be applied between the anode and the cathode. Furthermore, in some cases, a cell current 1 1 can be tapped. The biomass absorbs at the anode 2 electrons e- from the substrate, and outputs these at the cathode 3 to the substrate. Anode 2 and cathode 3 are connected to each other via an electrical line 12 to ensure the flow of electrons. Redox reactions take place at anode 2 and at cathode 3, respectively, ie at the electrode surfaces 4, either in the case of reduction, electrons are released from the biofilm to the atoms, ions or molecules, or in the case of the oxidation of these. Depending on the application, substrate and redox couple is oxidized, for example, at the anode 2 and reduced at the cathode 3.

A commonly present aqueous environment is optionally anaerobic, anoxic or aerobic adjustable. A possibly gaseous environment In microbial catalysis, water or substra tion rinsing (see growth body / trickling filter) on an electrode is characterized by partially submerged execution (see disc submersible or static, semi-submerged system) or by cultivation at high air humidity. The gaseous environment is therefore characterized in microbial catalysis by the simultaneous presence of water. It is either aerobic or anaerobic adjustable.

FIG. 2 shows an additional arrangement of the device 1 according to the invention for the bioelectrochemical conversion of substrate. In a reactor 13 either an anode 2 and / or a cathode 3 is arranged. The reactor 13 is filled via the inlet 14 with substrate and emptied by means of the drain 15. The emitted by the substrate present in the atoms, ions and molecules or captured electrons e ^~ be performed via an electrical line 16 to either a consumer or provided by an external power source. This arrangement is both in the field of wastewater treatment and in the field of methane production, for example in biogas plants, usable, here on the one hand a sewage treatment and on the other hand, the methane production takes place. By converting the particles present in the substrate, for example, the purification of wastewater in sewage treatment plants or the production of methane in biogas plants is realized. By using the arrangement in conjunction with an anode 2, for example, the yield of methane in a biogas plant can be increased. The arrangement can be retrofitted in biogas plants. The system can also be retrofitted for wastewater treatment. There is also the possibility of the electrode rotatable in the form of a stirrer, in particular an anchor, a Schrägblattrührers or the like to design, resulting in an optimized substrate mixing. An additional arrangement of the device according to the invention is shown in FIG. Here, for example, two different substrates are fed into two different reactors 17 and 18 via feeds 19 and 20. Via the outlet 21, the substrate is guided out of reactor 17. Reactor 18 is emptied by means of drain 22. The anode 2 arranged in the reactor 17 is connected via an electrical line 23 to the cathode 3 arranged in the reactor 18, whereby an electron transport from the reactor 17 to the reactor 18 is made possible. The embodiment can be configured with all advantageous arrangements, such as, for example, rotatable electrodes for optimal mixing of the reactors 17 and 18. A proton transport can be realized here via a material line 24, in particular a salt bridge.

The method for bioelectrochemical conversion works as explained in more detail below. In at least one reactor 6, 8, 13, 17 or 18, at least one Gleichpolige electrode, anode 2 or cathode 3, arranged. This is connected via an electrical line 12, 16 or 23 in the case of an anode 2 to a consumer and in the case of a cathode 3 to a power source which removes or delivers the emitted or absorbed from the substrate electrons. The substrate is fed via at least one inlet 5, 14, 19 or 20 to the at least one reactor 6, 8, 13, 17 or 18 and via at least one at the reactor 6, 8, 13, 17 or 18 arranged outlet 9, 15, 21st or 22 discharged. Redox reactions, which are catalyzed by biomass, take place at the electrode and cause the conversion of the substance. LIST OF REFERENCE NUMBERS

1. Device

2. anode

3rd cathode

4. Electrode surfaces

5. Feed

6th reactor

7. substance line

8. reactor

9. Procedure

10. cell voltage

1 1st cell current

12th electrical line

13th reactor

14. Feed

15. Procedure

16. electrical line

17th reactor

18th reactor

19. Feed

20. Feed

21. Process

22nd process

23. electrical line

24. Material line

Claims

Apparatus and method for bioelectrochemical conversion (inducing a reduction / oxidation / redox reaction). Claims

1. Device (1) for bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous state with at least one inlet (5, 14, 19, 20) and at least one outlet (9, 15, 21, 22)

characterized in that in at least one reactor (6, 8, 13, 17, 18) at least one anode (2) and / or at least one cathode (3) is arranged.

2. Device (1) according to claim 1,

characterized in that a biofilm is applied to the at least one anode (2) and / or at least one cathode (3).

3. Device (1) according to claim 2,

characterized in that the biofilm on the at least one anode (2) and / or the at least one cathode (3) is a sessile biofilm.

4. Device (1) according to one of the preceding claims, characterized in that at the at least one anode (2) and / or the at least one cathode (3) for electron transport, an electrical conductor (12, 16, 23) is arranged.

5. Device (1) according to one of the preceding claims,

characterized in that between the at least one anode (2) and the at least one cathode (3) for electron transport, an electrical conductor (12, 16, 23) is arranged.

6. Device (1) according to one of the preceding claims,

characterized in that the device (1) has a substance line (7, 24) for the proton transport between the at least one anode (2) and / or the at least one cathode (3).

7. Device (1) according to claim 6,

characterized in that the material line (7, 24) for the proton transport is a salt bridge or the like.

8. Device (1) according to one of the preceding claims,

characterized in that a plurality of reactors (6, 8, 13, 17, 18) are present, which are connected in cascade.

9. Device (1) according to one of the preceding claims,

characterized in that a balance of the bioelectrochemical equilibrium takes place by means of external energy intervention.

10. Device (1) according to one of the preceding claims, characterized in that the at least one anode (2) and / or the at least one cathode (3) cause a mixing of the at least one reactor (6, 8, 13, 17, 18).

1 1. Device (1) according to one of the preceding claims,

characterized in that the device (1) is controlled by a controller.

12. Device (1) according to claim 1 1,

characterized in that the control is carried out by means of online or inline metrology.

13. Method for the bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous state with at least one inlet (5, 14, 19, 20) and at least one outlet (9, 15, 21, 22)

characterized in that by means of the at least one inlet (5, 14, 19, 20) reactants are fed to at least one reactor (6, 8, 13, 17, 18) and there by means of at least one anode (2) and / or at least one Cathode (3) be converted bioelectrochemically.

14. The method according to claim 13,

characterized in that the at least one anode (2) and / or the at least one cathode (3) are exposed to a changing medium in one phase.

15. The method according to claim 13 or claim 14, characterized in that the bioelectromagnetic material conversion device (1) used is a device (1) according to any one of claims 1 to 12.