DE102013007659A1 - Apparatus and method for bioelectrochemical conversion (providing reduction / oxidation / redox reaction) - Google Patents

Abstract

The invention relates to a device (1) 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) and a method for operating the device (1), wherein in at least one reactor (6, 8, 13, 17, 18) at least one anode (2) and / or at least one cathode (3) is arranged by means of at least an inlet (5, 14, 19, 20) reactants are fed to the at least one reactor (6, 8, 13, 17, 18) and there bioelectrochemically by means of the at least one anode (2) and / or the at least one cathode (3) be converted or implemented.

Description

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 the treatment 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. For example, the patents AT 265152 and AT 81109 E , are a high energy input, a low energy yield, a partially high surplus sludge production, a limited substrate spectrum and partially limited efficiencies.

The well-known chemical-physical processes, such as the patent DD 244 743 A1 , 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 of the invention, in the international patent application WO 2011/006939 is disclosed. 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 in cleaning, as oxygen (or air) is blown in until the processing substrate has been relatively completely oxidized. This is associated with the disadvantage of high sludge production and high additional energy requirements. The high efficiencies of 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"). Also, the energy input to be made here is limited, since the energy must be expended only for the mixing of the substrate. Disadvantages here are also 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, reduction or 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 waste water, liquid manure, biogas plants and the like. With reduced energy input and possibly energy surplus, or synthesis product generation (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, regardless of 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. It is possible according to the invention to individually carry out reduction, to carry out or separate from one another, or to allow redox reactions between partners whose redox potential would otherwise 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, there is a direct electron uptake and release by means of the catalyzing biomass, whereby the usually very large concentration gradient between the fixed on the at least one electrode biofilm and the surrounding substrate is reduced. Sessile biofilm catalyzing the process produces less excess sludge. Furthermore, due to the omission of the introduction of elemental oxygen as a terminal electron acceptor, a further reduction of 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. Through this Arrangement, the electrons picked up 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 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 lack of 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 is always ideally mixed with its pollution load 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 for process control are always available. 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 state 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 the spatial separation of electron donor and acceptor, with potential savings in any feedback or with additional degrees of freedom in the setting of the environmental conditions, in the sole Oxidation or reduction, or during 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. It can process conditions are created that favor the subsequent overlay 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 can also be treated. 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 an arrangement of the device according to the invention,

2 an additional arrangement of the device according to the invention with only one reactor and an electrode and

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

Description of the embodiments

In 1 is an arrangement of the device according to the invention 1 illustrated by an embodiment and described below. In the 1 shown arrangement for bioelectrochemical material conversion consists of a rotatable anode 2 and a rotatable cathode 3 wherein both the anode and the cathode are electrode surfaces 4 exhibit. 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, at least one of the electrode surfaces 4 the two half elements a biofilm, in particular a sessile biofilm, which serves as a catalyst in the process, arranged. A coating of the electrode surfaces 4 with the biofilm can either be made in advance or takes place 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 over the inlet 5 in the reactor 6 and from there by means of a material line 7 in the reactor 8th transports and leaves it via the process 9 clean up the process. The substance 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, ie, low cell voltage 10 can be applied between the anode and cathode. Furthermore, in some cases, a cell stream 11 be tapped. The biomass increases at the anode 2 Electrons e ^- from the Substrate on, or gives this at the cathode 3 to the substrate. anode 2 and cathode 3 are interconnected via an electrical line 12 connected to ensure the flow of electrons. At anode 2 and at the cathode 3 Redox reactions take place, ie at the electrode surfaces 4 either in the case of reduction, electrons e ^{- 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, for example, at the anode 2 oxidized and at the cathode 3 reduced.

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

2 represents an additional arrangement of the device according to the invention 1 for the bioelectrochemical conversion of substrate. In a reactor 13 is either an anode 2 and / or a cathode 3 arranged. The reactor 13 will be over the inlet 14 filled with substrate and by means of the process 15 emptied. The emitted by the substrate present in the atoms, ions and molecules or captured electrons e ^- are via an electrical line 16 either led to 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 in 3 shown. Here are two, for example, different substrates in two different reactors 17 and 18 about feeds 19 and 20 guided. About the process 21 the substrate becomes reactor 17 guided. reactor 18 is by means of expiration 22 emptied. The in reactor 17 arranged anode 2 is via an electrical line 23 with the in reactor 18 arranged cathode 3 connected, whereby an electron transport from reactor 17 to reactor 18 is possible. The embodiment can be used with all advantageous arrangements, such as rotatable electrodes for optimal mixing of the reactors 17 and 18 be designed. A proton transport can here over a Stoffleitung 24 , in particular a salt bridge, be realized.

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

LIST OF REFERENCE NUMBERS

1

contraption

2

anode

3

cathode

4

electrode surfaces

5

Intake

6

reactor

7

fuel line

8th

reactor

9

procedure

10

cell voltage

11

cell current

12

electrical line

13

reactor

14

Intake

15

procedure

16

electrical line

17

reactor

18

reactor

19

Intake

20

Intake

21

procedure

22

procedure

23

electrical line

24

fuel line

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• AT 265152 [0002]
• AT 81109 E [0002]
• DD 244743 A1 [0003]
• WO 2011/006939 [0005]

Cited non-patent literature

• "Römpp-Lexikon; Biotechnology aerobic wastewater treatment [0006]

Claims (15)

Contraption ( 1 ) for the bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous state with at least one feed ( 5 . 14 . 19 . 20 ) and at least one process ( 9 . 15 . 21 . 22 ) characterized in that in at least one reactor ( 6 . 8th . 13 . 17 . 18 ) at least one anode ( 2 ) and / or at least one cathode ( 3 ) is arranged. Contraption ( 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 ) is applied. Contraption ( 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. Contraption ( 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 an electron transport an electrical conductor ( 12 . 16 . 23 ) is arranged. Contraption ( 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 an electron transport an electrical conductor ( 12 . 16 . 23 ) is arranged. Contraption ( 1 ) according to one of the preceding claims, characterized in that the device ( 1 ) a substance line ( 7 . 24 ) for the proton transport between the at least one anode ( 2 ) and / or the at least one cathode ( 3 ) having. Contraption ( 1 ) according to claim 6, characterized in that the substance line ( 7 . 24 ) is a salt bridge or the like for proton transport. Contraption ( 1 ) according to one of the preceding claims, characterized in that a plurality of reactors ( 6 . 8th . 13 . 17 . 18 ) are present, which are connected as a cascade. Contraption ( 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. Contraption ( 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 ) a mixing of the at least one reactor ( 6 . 8th . 13 . 17 . 18 ) cause. Contraption ( 1 ) according to one of the preceding claims, characterized in that the device ( 1 ) is controlled by a controller. Contraption ( 1 ) according to claim 11, characterized in that the control is carried out by means of online or inline measurement technology. Process for the bioelectrochemical conversion of organic and / or inorganic substances aqueous and / or gaseous state with at least one feed ( 5 . 14 . 19 . 20 ) and at least one process ( 9 . 15 . 21 . 22 ) characterized in that by means of the at least one inlet ( 5 . 14 . 19 . 20 ) Starting materials for at least one reactor ( 6 . 8th . 13 . 17 . 18 ) are fed and there by means of at least one anode ( 2 ) and / or at least one cathode ( 3 ) are converted bioelectrochemically. 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 environment in one phase. Method according to claim 13 or claim 14, characterized in that the device used ( 1 ) for bioelectrochemical conversion a device ( 1 ) according to one of claims 1 to 12.

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