Bioreactor system and associated components and methods

Abstract

A bioreactor system comprising a bioreactor vessel and an electrode system is provided. The electrode system comprises: a plurality of electrode pairs spaced apart in the bioreactor vessel; an electrical circuit configured to apply, to each electrodes pair, a voltage between the electrode pair; and for each of three or more subsets of the electrode pairs, a corresponding sensor configured to determine current data for the subset of the electrode pairs. An electrode system is also provided. A method of monitoring operational performance of a bioreactor system is also provided, along with a hardware for storing and / or executing such a method, where computer implemented. The method comprises obtaining one or more trends in data related to operation of the bioreactor system; and determining whether a system state indicating unstable system operation is present and / or a system state indicating stable operation is absent based on the one or more trends. Said determination is made by: obtaining a hierarchical list of system states, the hierarchical list in order of decreasing significance of impact of the system state on the operational stability of the bioreactor system; sequentially determining, in the order of said hierarchical list, whether or not a system state of said list is present based on the one or more trends; and where a system state indicating unstable system operation is determined to be present, or a system state indicating stable operation is determined not to be present, outputting said system state and ceasing determination of the presence of further system states in said hierarchical list.

Description

[0001] BIOREACTOR SYSTEM AND ASSOCIATED COMPONENTS AND METHODS This application claims priority from GB2501168.5 filed 27 January 2025, the contents and elements of which are herein incorporated by reference for all purposes.

[0002] Field of the Invention

[0003] The present invention relates to a bioreactor system and associated components and methods, and particularly, although not exclusively, to bio-electrochemical reactor systems for use in the treatment and processing of wastewater and / or organic material for the production of biogas.

[0004] Background

[0005] Bioreactors, such as bioelectrochemical systems (BES), may be used to process wastewater and / or organic waste to produce electricity and / or fuel such as biogas. Some such systems may include microorganisms located inside a chamber of the bioreactor for anaerobically digesting input waste to produce biogas comprising, for example, methane.

[0006] The operation and efficiency of BES may, however, be very unstable and susceptible to influence by any of a large number of parameters associated with the BES. For this reason, it is often necessary to monitor the conditions in bio-electrochemical reactor systems to improve the operation and efficiency of the bioreactor. This has generally involved collecting samples from the chamber of a bioreactor, taking the samples to a laboratory, and subjecting the samples to suitable laboratory tests to determine the environmental conditions of the bioreactor. Where in-situ measurements are conducted, these typically assume homogenous conditions throughout the bioreactor.

[0007] The present invention has been devised in light of the above considerations.

[0008] Summary of the Invention

[0009] In a first aspect, there is provided a bioreactor system comprising: a bioreactor vessel; an electrode system, the electrode system comprising: a plurality of electrode pairs spaced apart in the bioreactor vessel; an electrical circuit configured to apply, to each electrode pair, a voltage between the electrode pair; and for each of three or more subsets of the electrode pairs, a corresponding sensor configured to determine current data for the subset of the electrode pairs.

[0010] The bioreactor systems described herein may, for example, be bio-electrochemical reactor systems. As used herein, these terms are used interchangeably such that any reference to bio-electrochemical reactor systems may refer, more broadly, to bioreactor systems, and vice versa any reference to bioreactor systems may also refer, more specifically to bio-electrochemical reactor systems.8911901

[0011] 2

[0012] Typically, in bio-electrochemical reactor systems, for example, for anaerobic digestion of organic material, the contents of the vessel are assumed to be homogenous for the purposes of analysis and control. In some cases, there may be monitoring of conditions at the entrance and exit of the vessel. However, the present inventors have established that bio-electrochemical reactor systems may not be well represented by assuming the contents of the vessel to be homogenous, leading to poor monitoring and control of the operation of such systems. Moreover, different zones of the reactor have been found to be responsible for different electrochemical reactions, and to have different microorganisms present on electrode pairs present in different zones, accordingly, independent monitoring of such zones can improve understanding of the system’s operation and improve control thereof. The current, or current density, through an electrode pair has been found be directly related to bio-electrochemical activity at that electrode pair. Consequently, the present system is configured to allow current data for three or more subsets of the electrode pairs in the reactor to be determined, thereby providing a greater understanding of operation across the different zones of the vessel in real time, and in turn better control of the system for more efficient operation (e.g. increased reaction rates, reduced shutdown time, increased rate of product formation, etc.).

[0013] It can be understood that each subset of electrode pairs may comprise a single electrode pair, or may comprise a plurality of electrode pairs. By way of example, the electrode system may comprise 16 or 32 electrode pair, and these may be separated into three or more, e.g. four, subsets of electrode pairs, each subset with a corresponding sensor configured to determine current data for said subset.

[0014] The current data may, for example, include data indicative of a value of current and / or current density drawn through each subset of the electrode pairs during operation of the bioreactor. The current data may, for example, include data that aggregates the total flow of current and / or current density for the entire subset. Additionally or alternatively, the current data may, for example, include data indicative of a value of current and / or current density drawn through each individual electrode pair of the given subset. The arrangement of the electrical circuit and the sensors within the electrode system can be configured to provide such different types of current data, as the skilled person would understand.

[0015] The current data may be useful for determining the efficiency and / or stability of the bio-electrochemical processes inside the chamber because, the such bio-electrochemical process (e.g. the digestion of organic material by microorganisms) may generate electrons which are transferable to a nearby electrode (e.g. from a microorganism on, or adjacent, an electrode to that electrode), thereby inducing a return current flow in the corresponding electrode. Current measurements may therefore provide information indicative of the reaction rates of bio-electrochemical processes (e.g. microbial electrolysis) occurring at each subset of electrode pairs or individual electrode pairs.

[0016] Whilst the use of electrode pairs as sensors in bio-electrochemical systems are known, by collecting the current data from the same electrodes as the electrodes used to deliver voltage to induce or increase bioelectrochemical reactions (e.g. microbial electrolysis), the structural complexity of the bioreactor may be reduced, not least because only one electrode system need be provided, rather than separate systems for sensing and inducing bio-electrochemical reactions.8911901

[0017] 3

[0018] The sensors configured to determine current data may be ammeters.

[0019] The bioreactor vessel may comprise an inlet and an outlet, a downstream direction extending from the inlet to the outlet. In some examples, the bioreactor vessel may comprise a plurality of inlets, such as a feeding inlet and a recirculation inlet. In some examples, the bioreactor vessel may comprise a plurality of outlets, for example a liquid-phase outlet and a gas-phase outlet. Typically, where a plurality of inlets and / or outlets are present, the plurality of inlets are positioned adjacent each other, and / or the plurality of outlets are positioned adjacent each other, such that a downstream direction is still defined between said inlet(s) and outlet(s). The electrode system may comprise a first subset of the electrode pairs having a corresponding sensor configured to determine current data for the first subset, the first subset positioned adjacent the inlet; a second subset of the electrode pairs having a corresponding sensor configured to determine current data for the second subset, the second subset positioned downstream of the first subset; and a third subset of the electrode pairs having a corresponding sensor configured to determine current data for the third subset, the third subset positioned downstream of the second subset. In this way, the subsets of electrode pairs are spaced apart form each other in the downstream direction, thereby providing current data from different positions along a flow path through the bioreactor vessel. As discussed above, bio-electrochemical reactor systems may not be well represented by assuming the contents of the vessel to be homogenous, leading to poor monitoring and control of the operation of such systems, which is addressed by this configuration that allows for spatially resolved monitoring of conditions within the bioreactor vessel. Moreover, different zones of the reactor have been found to be responsible for different electrochemical reactions, and to have different microorganisms present on electrode pairs present in different zones, accordingly, independent monitoring of such zones can improve understanding of the system’s operation and improve control thereof.

[0020] One or more subsets of the electrode pairs may be independently addressable to apply a voltage between the one or more electrode pairs of the subset. In bio-electrochemical reactor systems, the voltage applied to an electrode supporting a bio-electrochemical reaction can influence the rate of that reaction. In the case of microbial electrolysis, for example, the voltage applied to the electrode may alter the rate at which a reaction is occurring and / or whether the reaction occurs at all. Accordingly, having subsets of the electrode pairs be independently addressable to apply a voltage between the electrode pairs of the subset allows the bio-electrochemical activity at the electrodes within each subset to be controlled independently of other subsets of electrode pairs. That is, a voltage may be applied between each of the electrode pairs contained within a subset of the electrode pairs independently of the other electrode pairs / subsets of electrode pairs in the electrode system. In some examples, the electrode system may be configured such that a voltage may be applied to each electrode pair in the electrode system independently of the other electrode pairs in the electrode system. This can provide even more precise control over the bio-electrochemical reactor system. In some examples, each of the subsets of electrode pairs may be connected to independent voltage supplies. In other examples, a plurality, or all, of the subsets of electrode pairs may share a common voltage supply and the electrical circuit may be configured with a potential divider to make each subset of the electrode pairs independently addressable with respect to the voltage.8911901

[0021] 4

[0022] One or more of subsets of the electrode pairs that is independently addressable to apply a voltage between the one or more electrode pairs of said subset may have a corresponding sensor configured to determine current data for said subset. That is, a subset of the electrode pairs that comprises a senor configured to determine the current data may also be addressable to apply a voltage to the electrode pairs contained in that subset independently of the other electrode pairs / subsets of electrode pairs in the electrode system. As discussed above, the voltage applied to an electrode pair may alter the activity of bio-electrochemical processes at that electrode pair, and current data for an electrode pair has been found be directly related to bio-electrochemical activity at that electrode pair. Accordingly, the controllability of the bio-electrochemical reactor system is improved where the subsets of electrode pairs that are independently addressable to apply a voltage thereto are mapped to the subsets of electrode pairs for which a corresponding sensor is configured to determine current data. By way of example, one or more of the first subset of electrode pairs, the second subset of electrode pairs, and the third subset of electrode pairs may be independently addressable to a apply a voltage between the one or more electrode pairs of said subsets. In some examples, the electrode system may comprise a plurality of sensors configured to determine current data, each sensor configured to determine current data for a corresponding electrode pair; This can provide even more precise monitoring of the activity in the bioelectrochemical reactor system.

[0023] The bio-electrochemical system may comprise a zonal control unit configured to deliver a signal to apply a voltage across each pair of electrodes within a given subset and / or configured to receive current data from the sensor(s) corresponding to a given subset. The bio-electrochemical system may further comprise a central control unit configured to receive data from and / or transmit data / control commands to, the zonal control units. The zonal control units may further be configured to communicate with respectively adjacent zonal control units. This may facilitate the determination of spatial variations and / or trends in the determined operational performance and so may facilitate a refined spatially aware control of the control variables of the system within each zone of the bioreactor vessel.

[0024] The bio-electrochemical reactor system may further comprise one or more additional sensors configured to determine operational data of the system. The additional sensors may be configured to determine operational data of the system that is different to the current data, i.e. the sensors may determine data relating to a parameter other than current or current density. The additional sensors may also be associated with a zone of the bioreactor vessel, and accordingly associated with a corresponding subset of the electrode pairs. One or more of the zonal control units may be further configured to receive data from additional sensors associated with the respective zones of the bioreactor vessel that said zonal control units are associated with.

[0025] The system may further comprise one or more of: a gas outlet from the bioreactor vessel and an additional sensor configured to determine gas flow data for the gas outlet and / or an additional sensor configured to determine gas composition data for the gas outlet; an additional sensor configured to determine temperature data for the bioreactor vessel; an additional sensor configured to determine pH data for the bioreactor vessel; an additional sensor configured to determine organic material loading rate8911901

[0026] 5

[0027] data; for one or more subsets of the electrode pairs, a corresponding additional sensor configured to determine voltage data for the subset of the electrode pairs; an additional sensor configured to determine liquid turbidity data, an additional sensor configured to determine volatile fatty acid concentration data, an additional sensor configured to determine chemical oxygen demand data, and an additional sensor configured to determine biochemical oxygen demand data, and / or one or more additional sensors configured to determine any of: a flow rate of organic material into the vessel, a pressure within a headspace of the vessel into which produced gas expands as it is produced, a liquid level within the vessel, a concentration of methane (or other gas such as oxygen, ammonia or nitrogen) dissolved in liquid in the vessel, a turbidity of liquid inside the vessel, a total concentration of suspended solids in liquid in the vessel, an oxidation-reduction potential of the organic material inside the vessel, a water pressure of liquid in the vessel, and / or operational data such as mixing timings, feeding cycle timings, and / or recirculation timings.

[0028] The gas flow data may, for example, include data indicative of the flowrate (e.g. volumetric or gravimetric flowrate) of gas through the gas outlet. The gas composition data may, for example, include data indicative of the concentration of one or more chemical species in the gas flowing through the gas outlet, e.g. methane concentration. The temperature data may, for example, include data indicative of the temperature of a liquid phase and / or a gas phase within the bioreactor vessel. The pH data may, for example, include data indicative of the pH of a liquid phase within the bioreactor vessel. The organic material loading rate data may, for example, include data indicative of the flowrate (e.g. volumetric or gravimetric flowrate) of organic matter-containing material (e.g. solid and / or liquid phases) into the bioreactor vessel. The voltage data may, for example, include data indicative of the aggregated voltage applied to each subset of the plurality of electrodes pairs during operation of the bio-electrochemical reactor. Additionally or alternatively, the voltage data may, for example, include data indicative of the voltage applied to each individual electrode pair within a corresponding subset. Voltage data can be useful for determining the which bio-electrochemical processes are occurring at the electrode pairs, and the efficiency and / or stability of those processes, as the voltage data may be useable to infer the extent to which bio-electrochemical processes are (or could be) enhanced and / or driven by the application of voltage to the electrode pairs. By obtaining the current data and voltage data for subsets of the plurality of pairs of electrodes, spatial distributions in the operational performance of the bioreactor may be determined. That is, a determined operational performance of the bio-electrochemical reaction system may account for spatial variations within the bioreactor vessel (e.g., across different subsets of the plurality of electrode pairs).

[0029] The gas composition data may, for example, include data indicative of the composition of the biogas (e.g., a percentage of the produced gas composed of methane, carbon dioxide, hydrogen, hydrogen sulphide, and / or oxygen).

[0030] One or more subsets of the electrode pairs that has a corresponding sensor configured to determine voltage data for the subset of the electrode pairs may further be independently addressable to apply a voltage between the one or more electrode pairs of said subset and / or may further have a corresponding8911901

[0031] 6

[0032] sensor configured to determine current data for said subset. The controllability of the bio-electrochemical reactor system is improved where the subsets of electrode pairs that are independently addressable to apply a voltage thereto are mapped to the subsets of electrode pairs for which corresponding sensors are configured to determine current data and voltage data. By way of example, one or more of the first subset of electrode pairs, the second subset of electrode pairs, and the third subset of electrode pairs may be independently addressable to a apply a voltage between the one or more electrode pairs of said subsets, and the electrode system may comprise sensors configured to determine voltage data for each of these subsets. In some examples, the electrode system may comprise a plurality of sensors configured to determine voltage data, each sensor configured to determine voltage data for a corresponding electrode pair; This can provide even more precise monitoring of the activity in the bio-electrochemical reactor system.

[0033] The bio-electrochemical reactor system may be configured for anaerobic digestion (AD) of organic material in the bioreactor vessel for the production of biogas. By way of example, the system may further comprise a feed pump configured to supply organic material into the bioreactor vessel via the inlet (e.g the feed inlet). In some examples, the organic material may be contained in wastewater. The bioreactor vessel may contain microorganisms for anaerobically digesting organic material (e.g. comprising acetate and hydrogen, amongst other compounds). The biogas may comprise methane, carbon dioxide and nitrogen, and optionally further trace gases (e.g. hydrogen gas and / or hydrogen sulphide gas). The bioelectrochemical reactor system, in particular the electrode system, may be configured for electromethanogenesis. Accordingly, the bioreactor vessel may contain methanogenic microorganisms for anaerobically digesting organic material to produce methane (e.g. as a component of the biogas). The electrode system may be configured for microbial electrolysis. Microorganisms may coat the plurality of electrode pairs (e.g. as a biofilm) such that, upon application of a voltage between a pair of electrodes, the microorganisms coating the electrodes are induced to conduct bio-electrochemical reactions, e.g. to breakdown organic material in their vicinity. That is, the microorganisms may be electrically active and their activity (e.g. AD activity) may increase in response to the application of voltage between the electrode pair they are provided on.

[0034] During operation of the bio-electrochemical reactor, the voltage applied across each pair of electrodes may be a relatively low voltage - e.g., approximately 1V. Such voltages may be sufficient to induce or increase digestive activity in the microorganisms, without risking damaging or even killing the microorganisms (e.g., by electrical burn). Typically, the voltage applied across a pair of electrodes is less than or equal to 2 volts, e.g. less than or equal to 1.5 volts.

[0035] The bio-electrochemical system may be configured to operate the bioreactor vessel as a continuous or semi-batch reactor. The present invention is particularly relevant where the bioreactor vessel is to be operated as a continuous or semi-batch reactor, as then it is even less accurate to take the conventional approach in BES of assuming that the bioreactor vessel contents are homogenous.8911901

[0036] 7

[0037] The bio-electrochemical system may be at an industrial scale. By way of example, the bioreactor vessel may have a volume of greater than or equal to 100 litres, or greater than or equal to 1000 litres, or greater than or equal to 10,000 litres.

[0038] In a second aspect, there is provided an electrode system for a bio-electrochemical reactor system, the electrode system comprising: a plurality of electrode pairs; an electrical circuit configured to apply, to each electrodes pair, a voltage between the electrode pair; and for each of three or more subsets of the electrode pairs, a sensor configured to determine current data for the subset of the electrode pairs. Any one or more of the optional features set out in respect of the first aspect are equally applicably to, and hereby restated in relation to, the second aspect, except where such a combination is clearly impermissible or expressly avoided.

[0039] One or more subsets of the electrode pairs may be independently addressable to apply a voltage between the one or more electrode pairs of the subset.

[0040] One or more subsets of the electrode pairs that is independently addressable to apply a voltage between the one or more electrode pairs of said subset may have a corresponding sensor configured to determine current data for said subset.

[0041] The electrode system may further comprise, for one or more subsets of the electrode pairs, a corresponding sensor configured to determine voltage data for the subset of the electrode pairs.

[0042] The electrode system may be configured for microbial electrolysis. The electrode system may be configured for electromethanogenesis.

[0043] In a third aspect, there is provided a method of operating the bio-electrochemical reactor system according to the first aspect. Any one or more of the optional features set out in respect of the first and / or second aspects are equally applicably to, and hereby restated in relation to, the third aspect, except where such a combination is clearly impermissible or expressly avoided.

[0044] The method may comprise obtaining current data for each of three or more subsets of the electrode pairs from the corresponding sensor.

[0045] The method may comprise feeding organic material into the bioreactor vessel. In some examples, the organic material may be contained in a wastewater. In some examples, the method may comprise feeding organic material into the bioreactor in regular but intermittent manner, spaced by periods in which no feeding of organic material occurs.

[0046] The method may comprise applying a voltage between one or more electrode pairs. In some examples, the method may comprise applying a voltage to electrode pairs of one or more subsets of the electrode pairs independently, for example, such that the voltage applied to the electrode pair(s) of one subset is different to the voltage applied to the electrode pair(s) of another subset.

[0047] The method may comprise drawing biogas from the bioreactor vessel. The method may comprise drawing a liquid phase from the bioreactor vessel. The liquid phase drawn from the bioreactor vessel may have a lower concentration of organic material than a liquid phase fed into the bioreactor.8911901

[0048] 8

[0049] The method may comprise operating the bioreactor vessel as a continuous or semi-batch reactor. The present invention is particularly relevant where operating the bioreactor vessel as a continuous or semibatch reactor, as then it is even less accurate to take the conventional approach in BES of assuming that the bioreactor vessel contents are homogenous.

[0050] In a fourth aspect, there is provided a method of determining operational performance of a bioreactor system, the method comprising: obtaining one or more trends in data related to operation of the bioelectrochemical reactor system; and determining whether a (bio-electrochemical reactor) system state indicating unstable system operation is present and / or a (bio-electrochemical reactor) system state indicating stable system operation is absent based on the one or more trends, wherein said determination is made by: obtaining a hierarchical list of (bio-electrochemical reactor) system states; sequentially determining, in the order of said hierarchical list, whether or not a (bio-electrochemical reactor) system state of said list is present based on the one or more trends and whether or not that system state indicates unstable system operation or stable system operation; and where a (bio-electrochemical reactor system) state indicating unstable system operation is determined to be present, or a system state indicating stable operation is determined not to be present, outputting said (bio-electrochemical reactor) system state and ceasing determination of the presence of further (bio-electrochemical reactor) system states in said hierarchical list.

[0051] Determining the operational performance of the bioreactor system may involve monitoring the operational performance of the bioreactor system (e.g., monitoring the operational performance overtime).

[0052] The hierarchical list may be in order of decreasing significance of impact of the system state on the operational stability of the bio-electrochemical reactor system. This significance of impact of the system state may be a metric, qualitative or quantitative, indicating the degree to which the system state impacts the operational stability of the bio-electrochemical reactor system (e.g. the magnitude of the change to the system stability when that system state is present).

[0053] By monitoring the operational performance of the bio-electrochemical reactor system according to the above method, it is possible to identify the presence of system states that are most significantly impacting the stable operation of the bio-electrochemical reactor system with reduced information processing (e.g. in faster time and / or with fewer resources), as the hierarchical ordering of the system states means that the presence (or absence) of system states less significant to stable operation is only determined after the presence (or absence) of system states more significant to stable operation have been determined, and as soon as a system state indicating unstable system operation is determined to be present or a system state indicating stable operation is determined to be absent, this system state is output and no determination of the presence of further system states of lesser significance is made. By way of example, where the bio-electrochemical reactor system is configured to process organic material, if the method determines that the system is not receiving organic material, then this is output as a system state indicating unstable system operation without determining whether the system state of a decrease in the feed rate of organic material (which it is not useful for an operator to be informed of if it has already been established that no organic material is being received by the system).8911901

[0054] 9

[0055] Any one or more of the optional features set out in respect of the first, second, or third aspects are equally applicably to, and hereby restated in relation to, the fourth aspect, except where such a combination is clearly impermissible or expressly avoided.

[0056] The operational stability of the bio-electrochemical reactor system may be represented by a production rate of a product of the bio-electrochemical reactor system, for example, a biogas production rate, e.g. a more stable system having a lower magnitude of the derivative of the rate of production of the product with respect to time. Additionally or alternatively, operational stability may be indicative of the resilience or robustness of the system against system failure. For example, the breakdown of organic compounds may lead to the accumulation of material (e.g., volatile fatty acids) that cause the pH inside the vessel to drop, thereby inhibiting the microbiological processes that take place to anaerobically digest organic material inside the vessel. As such, operational stability may be considered to be an indicator of the suitability of the environmental conditions within the vessel for stable and / or consistent execution of microbiological processes such as anaerobic digestion. Further, the operational stability may be indicative of the suitability of the environmental conditions for the occurrence of extracellular electron transfer to the electrode system by which one or more current measurements may be performed.

[0057] Where a system state indicating stable system operation is determined to be present or a system state indicating unstable system operation is determined to be absent based on the obtained trends, the method may proceed to determining whether the next system state in the hierarchical list is present or absent.

[0058] The one or more trends in data related to operation of the bio-electrochemical reactor system may be obtained by: obtaining data related to operation of the bio-electrochemical reactor system from a sensor; extracting one or more features from the data; and identifying one or more trends in the data from the one or more features.

[0059] Extracting features from the data may comprise one or more of: detecting signal spikes in the data; extracting average (e.g. mean) gradients in the data; identifying changes in the sign of average gradients in the data; extracting the variance in gradient in the data; detecting differences between data from two or more sensors (e.g. differences in current data from electrode pairs in different subsets of electrode pairs, such as adjacent subsets of electrode pairs, or differences in data from sensors whose signals are expected to be correlated (e.g. gas flowrate data and current data), such as differences in the mean gradients of the data, differences in the variance of gradients of the data between two or more sensors, or differences in the occurrence of signal spikes in the data; and detecting a signal spike and determining whether, following the signal spike, the data has returned to a stable value.

[0060] In some examples, the operation of the bio-electrochemical reactor system may be operated in a cyclical manner. By way of example, the system may be operated by regular periods of feeding of a reagent (e.g. organic material) into the system separated by periods where no feeding of a reagent into the system, thereby dividing the operation of the system into a plurality of cycles, each cycle containing a respective feeding time period and a time period in which no feeding of organic material occurs. In such cases,8911901

[0061] 10

[0062] trends in the data (and thus deviations from those trends) may be identified from the features extracted therefrom by comparing the features extracted from the data over a plurality cycles.

[0063] The method may be applied to monitoring the operational performance of a bio-electrochemical reactor system configured for anaerobic digestion of organic material in the bioreactor vessel for the production of biogas. The method may be applied to monitoring the operational performance of a bio-electrochemical reactor system configured for electromethanogenesis. The method may be applied to monitoring the operational performance of a bio-electrochemical reactor system configured for microbial electrolysis. The bio-electrochemical reactor system may comprise a plurality of sensors configured to determine operating data of the reactor system (e.g. one or more of current data for one or more subsets of electrode pairs, gas flow data for a gas outlet, gas composition data for the gas outlet, temperature data for the reactor system, pH data for the reactor system, organic material loading rata data for the system, voltage data for one or more subsets of electrode pairs, liquid turbidity data, volatile fatty acid concentration data; and chemical oxygen demand data).

[0064] In one example, the method may be applied to monitoring the operational performance of a bioelectrochemical reactor system according to the first aspect. In such a case, the data related to operation of the bio-electrochemical reactor system may comprise the current data for the subsets of the electrode pairs. As discussed above, the current, or current density, through an electrode pair has been found be directly related to bio-electrochemical activity at that electrode pair. Consequently, the present method utilising current data for three or more subsets of the electrode pairs in the reactor can thereby providing a greater understanding of operation across the different zones of the vessel in real time, and in turn better control of the system for more efficient operation (e.g. increased reaction rates, reduced shutdown time, increased rate of product formation, etc.).

[0065] Where the bio-electrochemical reactor system further comprises one or more additional sensors configured to determine operational data of the system, the data related to operation of the bioelectrochemical reactor system used in the present method may comprise data from such additional sensors. By way of example the data related to operation of the bio-electrochemical reactor system may comprise gas flow data for the gas outlet, gas composition data for the gas outlet, temperature data for the bioreactor vessel, pH data for the bioreactor vessel, organic material loading rate data, voltage data for one or more subsets of the electrode pairs, liquid turbidity data, volatile fatty acid concentration data, chemical oxygen demand data, and biochemical oxygen demand data. The present method utilising data from a range of sensors, and those sensors detecting conditions across different zones of the system / bioreactor vessel can result in a more holistic assessment of the operational performance of the bioelectrochemical reactor system, and thus better inform control of the system.

[0066] The hierarchical list of system states may include one or more of: the system is receiving an organic material feed; the system is not receiving an organic material feed; a spike is present in the organic material loading rate; a spike is not present in the organic material loading rate; the system is recovering from a downtime period; the system is not recovering from a downtime period; the system would provide a stable response to a potential organic material loading rate increase; the system would not provide a8911901

[0067] 11

[0068] stable response to a potential organic material loading rate increase; the system would provide a stable response to a potential organic material loading rate decrease; and the system would not provide a stable response to a potential organic material loading rate decrease. A hierarchical list in order of decreasing impact of the system state on the operational stability of the bio-electrochemical reactor system may be: whether or not the system is receiving an organic material feed; whether or not a spike in the organic material loading rate is present; whether or not the system is recovering from a downtime period; whether or not the system would provide a stable response to a potential organic material loading rate increase; and whether or not the system would provide a stable response to a potential organic material loading rate decrease.

[0069] Whether or not a system state indicates unstable system operation or stable system operation may be inherent to the individual system state and the configuration of the bio-electrochemical reactor system. Whether or not a system state indicates unstable system operation or stable system operation may be defined in a look-up table accessible during execution of the method. By way of example: the system receiving an organic material feed may indicate stable system operation; the system not receiving an organic material feed may indicate unstable system operation; a spike being present in the organic material loading rate may indicate unstable system operation; a spike not being present in the organic material loading rate may indicate stable system operation; the system recovering from a downtime period may indicate unstable system operation; the system not recovering from a downtime period may indicate stable system operation; the system being able to provide a stable response to a potential organic material loading rate increase may indicate stable system operation; the system not being able to provide a stable response to a potential organic material loading rate increase may indicate unstable system operation; the system being able to provide a stable response to a potential organic material loading rate decrease may indicate stable system operation; and the system not being able to provide a stable response to a potential organic material loading rate decrease may indicate stable system operation.

[0070] The presence or absence of a system state may be determined by checking whether or not one or more trends associated with the system state are present or absent in data related to operation of the bioelectrochemical reactor system.

[0071] For example, the one or more trends may include: an indication that the amount of methane (or other gas) being produced by the bioreactor system is declining over time; an indication that a current response of the electrode system exhibited a spike and subsequently returned to a stable (e.g., steady-state operational) value; an indication that the current response of the electrode system has dropped relative to previous feed cycles of the bioreactor system; and / or an indication that a concentration of methane within the produced biogas is declining between consecutive feed cycles of the bioreactor system.

[0072] The method may further comprise identifying one or more action states for operation of the bioelectrochemical reactor system based on the system state indicating unstable system operation identified as being present or the system state indicating stable system operation identified as being absent. The action states may be understood as control actions that can be implemented within the system to8911901

[0073] 12

[0074] influence the operation of the system. The one or more action states may include one or more of: determining if a control system of the bio-electrochemical reactor system is operating properly; determining if one or more feed pumps (e.g. an organic material feed pump) are operating properly; controlling a control variable of the bio-electrochemical reactor system; pausing feeding (e.g. feeding of organic material) to the system; conducting offline analysis (e.g. collecting a sample from the system for offline lab analysis); determining a cause of a downtime period (that is, a cause of a period of system failure or deactivation of the bioreactor system - e.g., voltage fault over / under-heating, a feed pumping error, a recirculation cycle or error, and / or a mixing operation); requesting human operator intervention; requesting human operator monitoring; adjusting an organic material loading rate (e.g. by adjusting operation of an organic material feed pump); and controlling a voltage applied between a pair of electrodes (e.g. where the bio-electrochemical system is that according to the first aspect).

[0075] Specifically, action states associated with a system state of the system not receiving an organic material feed may include one or more of determining if a control system of the bio-electrochemical reactor system is operating properly; controlling a voltage applied between a pair of electrodes (e.g. where the bioelectrochemical system is that according to the first aspect); and determining if one or more feed pumps (e.g. an organic material feed pump) are operating properly. Action states associated with a system state of a spike is present in the organic material loading rate may include one or more of: controlling a control variable of the bio-electrochemical reactor system; controlling a voltage applied between a pair of electrodes (e.g. where the bio-electrochemical system is that according to the first aspect); pausing feeding (e.g. feeding of organic material) to the system; and conducting offline analysis (e.g. collecting a sample from the system for offline lab analysis). Action states associated with a system state of the system is recovering from a downtime period may include one or more of: determining a cause of a downtime period; controlling a voltage applied between a pair of electrodes (e.g. where the bioelectrochemical system is that according to the first aspect); requesting human operator intervention; and requesting human operator monitoring. Action states associated with a system state of the system would not provide a stable response to a potential organic material loading rate increase may include one or more of: adjusting an organic material loading rate (e.g. by adjusting operation of an organic material feed pump); controlling a voltage applied between a pair of electrodes (e.g. where the bio-electrochemical system is that according to the first aspect); and conducting offline analysis (e.g. collecting a sample from the system for offline lab analysis). Action states associated with a system state of the system would not provide a stable response to a potential organic material loading rate decrease may include adjusting an organic material loading rate (e.g. by adjusting operation of an organic material feed pump); requesting human operator monitoring; and controlling a voltage applied between a pair of electrodes (e.g. where the bio-electrochemical system is that according to the first aspect) .

[0076] The method may further comprise implementing one or more of said action states. Accordingly, it can be understood that the method may be a method of controlling a bio-electrochemical reactor system.

[0077] Alternatively, the method may comprise presenting one or more of said actions states for selection by a user.8911901

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[0079] The method may be a computer-implemented method.

[0080] In a fifth aspect, there is provided a computer comprising a memory for storing data, and a processor configured to carry out the method according to the fourth aspect. Any one or more of the optional features set out in respect of the first, second, third, or fourth aspects are equally applicably to, and hereby restated in relation to, the fifth aspect, except where such a combination is clearly impermissible or expressly avoided. The memory may also, for example, store instructions that, when executed by the processor, cause the processor to carry out the method according to the fourth aspect.

[0081] In a sixth aspect, there is provided a computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to carry out the method of the fourth aspect. Any one or more of the optional features set out in respect of the first, second, third, fourth, or fifth aspects are equally applicably to, and hereby restated in relation to, the sixth aspect, except where such a combination is clearly impermissible or expressly avoided. The computer-readable medium may, for example, be stored in a memory of the computer, or may be stored remotely (e.g., on a server accessible to the computer).

[0082] In the described embodiments of the invention, the system may be implemented as any form of a computing and / or electronic device. Such a device may comprise one or more processors which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the device in order to gather and record routing information. In some examples, for example where a system on a chip architecture is used, the processors may include one or more fixed function blocks (also referred to as accelerators) which implement a part of the method in hardware (rather than software or firmware). Platform software comprising an operating system or any other suitable platform software may be provided at the computing-based device to enable application software to be executed on the device.

[0083] Moreover, the acts described herein may be embodied using computer-executable instructions that can be implemented by one or more processors and / or stored on a computer-readable medium or media. The computer-executable instructions can include routines, sub-routines; programs; threads of execution, and / or the like. Still further, results of acts of the methods can be stored in a computer-readable medium, displayed on a display device, and / or the like.

[0084] The order of the operations of the methods described herein is exemplary, but the steps may be carried out in any suitable order, or simultaneously where appropriate. Additionally, steps may be added or substituted in, or individual steps may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[0085] Various functions described herein can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media may include, for8911901

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[0087] example, computer-readable storage media. Computer-readable storage media may include volatile or non-volatile, removable or non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. A computer-readable storage media can be any available storage media that may be accessed by a computer. By way of example, and not limitation, such computer-readable storage media may comprise RAM, ROM, EEPROM, flash memory or other memory devices, CD-ROM or other optical disc storage, magnetic disc storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0088] Although illustrated as a local device it will be appreciated that the computing device may be located remotely and accessed via a network or other communication link (for example using a communication interface).

[0089] The term 'computer' is used herein to refer to any device with processing capability such that it can execute instructions. Those skilled in the art will realise that such processing capabilities are incorporated into many different devices and therefore the term 'computer' includes PCs, servers, mobile telephones, personal digital assistants and many other devices.

[0090] Those skilled in the art will realise that storage devices utilised to store program instructions can be distributed across a network. For example, a remote computer may store an example of the process described as software. A local or terminal computer may access the remote computer and download a part or all of the software to run the program. Alternatively, the local computer may download pieces of the software as needed, or execute some software instructions at the local terminal and some at the remote computer (or computer network). Those skilled in the art will also realise that by utilising conventional techniques known to those skilled in the art that all, or a portion of the software instructions may be carried out by a dedicated circuit, such as a DSP, programmable logic array, or the like.

[0091] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0092] Summary of the Figures

[0093] Embodiments and experiments illustrating a bio-electrochemical reactor system and associated components and methods will now be discussed with reference to the accompanying figures in which: Figure 1 is a schematic illustration of a bio-electrochemical reactor system;

[0094] Figure 2 is a graph showing the current response over time of different subsets of an electrode system; Figure 3 is a schematic illustration of a bio-electrochemical reactor system, wherein subsets of electrode pairs of an electrode system are independently addressable;

[0095] Figure 4 is a flowchart illustrating a method of monitoring operational performance of a bioelectrochemical reactor system; and8911901

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[0097] Figure 5 is a flowchart illustrating a method of determining whether a system state indicating unstable system operation is present and / or whether a system state indicating stable operation is absent based on one or more trends in data related to operation of the bio-electrochemical reactor system.

[0098] Detailed Description of the Invention

[0099] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. Figure 1 is a schematic illustration of a bio-electrochemical reactor system 100 having a bioreactor vessel 120 and an electrode system 200 installed therein.

[0100] For illustrative simplicity, the vessel 120 is depicted with a single inlet 112, 132, which may include one or both of a feeding inlet 112 and a recirculation inlet 132.

[0101] The bioreactor vessel 120 has contained therein a microorganism population for anaerobically digesting organic material received via the inlet 112, 132 to produce biogas. For example, the chamber may contain a methanogen population for anaerobically digesting organic material such as hydrogen and acetate to produce methane. The produced biogas is extracted from the bioreactor vessel 120 via a gas outlet 122.

[0102] As part of the operation of the bioreactor 100, not all of the organic material may be fully digested in a single pass of the bioreactor vessel 120. In such cases, undigested organic material is fed out of the bioreactor vessel 120 via a vessel outlet 124 and recirculated back into the chamber 120 for further anaerobic digestion via the recirculation inlet 132.

[0103] The presence of the electrode system 200 in the bioreactor vessel 120 is so that the system 100 can be operated as a bio-electrochemical reactor system 100 by a voltage being applied to electrode pairs such that microorganisms adjacent the electrode pairs conduct microbial electrolysis of the organic material fed to the bioreactor vessel. Such microorganisms coat the plurality of electrode pairs as a biofilm and are typically methanogenic microorganisms capable of undergoing electromethanogenesis to produce methane. The application of a voltage to an electrode pair instigates and / or enhances the activity of the methanogenic microorganisms.

[0104] The electrode system 200 comprises a plurality of electrodes pairs arranged into subsets 202, 204, 206, 208 of electrode pairs. Each of the subsets 202, 204, 206, 208 of electrode pairs is independently addressable via a respective zonal control unit 212, 214, 216, 218.

[0105] Each zonal control unit 212, 214, 216, 218 is configured to deliver a signal to the corresponding subset 202, 204, 206, 208 of electrode pairs to cause a voltage (e.g., a voltage of about 1 V) to be applied across each electrode pair within the subset 202, 204, 206, 208. In some cases, the voltage across each electrode pair within the subset may be the same (and typically different to the voltages across electrode pairs in other subsets), but independent voltage control for electrode pairs within the same subset may also be possible.8911901

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[0107] In addition to delivering a signal to apply voltage across each pair of electrodes within a given subset 202, 204, 206, 208, each zonal control unit 212, 214, 216, 218 is further configured to receive sensor data from a zone defined by the corresponding subset 202, 204, 206, 208 of electrode pairs. In particular, for each subset 202, 204, 206, 208 of electrode pairs, there is a corresponding sensor configured to determine current data for that subset 202, 204, 206, 208 of the electrode pairs, and each zonal control unit 212, 214, 216, 218 is configured to receive, for its corresponding subset 202, 204, 206, 208 of electrodes, the current data from the corresponding sensor. The system typically further comprises a plurality of additional sensors (e.g. for determining gas flow data, gas composition data, temperature data, pH data, organic material loading rate data, voltage data) that may also be associated with particular zones of the bioreactor vessel, and data from such additional sensors is collected by the corresponding zonal control unit 212, 214, 216, 218.

[0108] Additionally, collected data (and / or zonal operational performance determined therefrom) may be communicated from each of the zonal control units 212, 214, 216, 218 to a central control unit 220.

[0109] The central control unit 220 may monitor the operational performance of the bio-electrochemical reactor system based on the data it receives from the zonal control units, identify action states to be implemented, and control the system or components thereof to implement such action states. This is discussed further in relation to Figures 4 and 5 below.

[0110] Figure 2 illustrates current data from sensors in different (e.g. adjacent) zones of the bioreactor vessel, specifically, the variation in current drawn through the subsets of electrode pairs over time during operation of the bio-electrochemical reactor system.

[0111] Figure 2 shows a spike in the current response of a first subset of the electrode pairs at an initial time. This spike in the current response coincides with a spike in the organic material loading rate into the bioreactor vessel 120. That is, in response to organic feed being fed into the bioreactor vessel 120, the anaerobic digestive rate in a zone initially receiving the organic material (i.e. adjacent the inlet 112, 132) increases, thereby causing an increase in the current response measured by the sensor for the corresponding zonal unit.

[0112] At a later time, an increase in the current response of a second subset of the electrode pairs can also be seen in Figure 2. This second subset of the electrode pairs is downstream of the first subset - that is the second subset is arranged further from the feeding inlet 112 than the first subset. Accordingly, the current spike in the current response of the second subset at a time later than the initial time is indicative that the organic material is flowing through the chamber and through each of the zones. Additionally, the current spike in the current response of the second subset is indicative that at least some of the organic material fed into the chamber is not fully digested by microorganisms in upstream zones. For example, if there were no current spike in the current response of any one of the subsets corresponding to a zone downstream of the first subset, this may indicate that the organic material is fully digested before flowing all the way through the vessel 120 and, therefore, that the organic material loading rate may be increased to increase the biogas yield.8911901

[0113] 17

[0114] Figure 2 thereby illustrates the importance of independent monitoring and control of different special zones of the bioreactor vessel 120.

[0115] Figure 3 is a schematic illustration of a bioreactor vessel and an associated electrode system. Figure 3 shows each subset of the electrode pairs 302, 304, 306, 308 including multiple electrode pairs arranged in an array. The zonal control units 312, 314, 316, 318 are configured to each respectively and independently apply a voltage across the electrodes of the corresponding subset 302, 304, 306, 308 and to measure the current and / or current density drawn through the corresponding subset 302, 304, 306, 308.

[0116] Each of the zonal control units 312, 314, 316, 318 is further configured to communicate with a central control unit 310 for monitoring the operational performance of the bioreactor.

[0117] Further, each of the zonal control units 312, 314, 316, 318 is configured to communicate with respectively adjacent zonal control units. This may facilitate the determination of spatial variations and / or trends in the determined operational performance (as illustrated in Figure 2) and so may facilitate a refined spatially aware control of the control variables of the system within each zone of the bioreactor vessel.

[0118] Figure 4 is a flowchart illustrating a method of monitoring operational performance of a bioelectrochemical reactor system, such as the bio-electrochemical reactor system discussed in Figures 1 -3.

[0119] At its broadest, the method comprises obtaining one or more trends in data related to operation of the bioelectrochemical reactor system, which can be conducted using steps S100 - S300, and determining whether a bio-electrochemical reactor system state indicating unstable system operation is present based on the one or more trends, which can be conducted using step S400.

[0120] At step S100, data related to operation of the bio-electrochemical reactor system is obtained. Considering the bio-electrochemical reactor system discussed in Figures 1 - 3, such data may comprise the current data for the subsets of the electrode pairs, which is directly related to bio-electrochemical activity at the electrode pairs. Data relating to operation of the bio-electrochemical reactor system may also be obtained from the addition sensors discussed above in relation to figure 1, e.g. sensors for obtaining pH data, gas flow data etc. To obtain data relating to conditions in different zones of the bioreactor vessel, step S100 may collect current data relating to three or more different subsets of electrode pairs, and possibly also from additional sensors obtaining data relating to different zones of the bioreactor vessel (e.g. by the central control unit communicating with multiple zonal control units, or by communication between adjacent zonal control units.

[0121] Subsequently, at step S200, statistical feature extraction on the data obtained at step S100 is conducted. Extracting features from the data may comprise one or more of: detecting signal spikes in the data; extracting average (e.g. mean) gradients in the data; identifying changes in the sign of average gradients in the data; extracting the variance in gradient in the data; detecting differences between data from two or more sensors (e.g. differences in current data from electrode pairs in different subsets of electrode pairs, such as adjacent subsets of electrode pairs), such as differences in the mean gradients of the data or8911901

[0122] 18

[0123] differences in the variance of gradients of the data between two or more sensors; and detecting a signal spike and determining whether, following the signal spike, the data has returned to a stable value.

[0124] At step S300, one or more trends in the data are identified based on the one or more features extracted from the data at step S200. Typically, the bio-electrochemical reactor system is operated by regular periods of feeding of organic material into the bioreactor vessel, separated by periods where no feeding occurs, thereby dividing the operation of the system into a plurality of cycles, each cycle containing a respective feeding time period and a time period in which no feeding of organic material occurs. Trends in the data may be identified from the features extracted by comparing the features extracted from the data over a plurality cycles.

[0125] Subsequently, as step S400, the method comprises determining whether a system state indicating unstable system operation is present based on the one or more trends identified at step S300. Step S400 is discussed in more detail with reference to Figure 5 below. Crucially, the determination is done in a hierarchical manner, such that system states having a more significant impact on the operational stability of the system are considered first, and system states having a less significant impact on the operational stability of the system are only considered if system states having a more significant impact and indicating unstable operation of the system are not determined to be present. In this way, it is possible to identify the system states that are most significantly impacting the stable operation of the bio-electrochemical reactor system with reduced information processing (e.g. in faster time and / or with fewer resources), as the hierarchical consideration of the system states means that the presence (or absence) of system states less significant to stable operation is only determined after the presence (or absence) of system states more significant to stable operation have been determined.

[0126] Following determination of the system state (or absence thereof) that is leading to unstable system operation, at step S500 the method further comprises identifying one or more action states for operation of the bio-electrochemical system. The action states may be understood control actions that can be implemented within the system to influence the operation of the system. Each system state (or absence thereof) that is leading to unstable system operation has one or more associated action states that, when implemented, address the instability of the system and / or provide information on a root cause of the unstable system operation. By way of example, if the system state identified as being present at step S400 is that the system is not receiving an organic material feed, then possible action states include determining if a control system of the bio-electrochemical reactor system is operating properly and determining if one or more feed pumps (e.g. an organic material feed pump) are operating properly. Finally, at step S600, the method comprises implementing one or more of the identified action states to influence the operation of the system to address the instability of the system and / or to provide information on a root cause of the unstable system operation.

[0127] Figure 5 is a flowchart illustrating a method of conducting step S400 of determining whether a system state indicating unstable system operation is present and / or a system state indicating stable operation is absent based on the one or more trends in data related to operation of the bio-electrochemical reactor system identified at step S300.8911901

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[0129] The determination is made by firstly obtaining a hierarchical list of system states, the hierarchical list in order of decreasing significance of impact of the system state on the operational stability of the bioelectrochemical reactor system. Examples of the system states included list are provided by steps S410 to S450 in Figure 5 (i.e. the system is receiving organic material feed, the system has had a large spike in organic material loading rate, the system is recovering from a downtime period, the system would respond stably to a potential increase in the organic material loading rate, the system would respond stably to a potential decrease in the organic material loading rate). Subsequently, as illustrated by Figure 5, step S400 comprises sequentially determining, in the order of said hierarchical list, whether or not a system state of said list is present based on the one or more trends and whether or not that system state indicates unstable system operation or stable system operation. Where a system state indicating stable system operation (e.g. the system is receiving organic material feed) is determined to be present based on the obtained trends, the determination proceeds to the next system state (see arrow from S410 to S420 in Fig. 5 where ‘check if system receiving organic material feed’ is answered ‘YES’). Where a system state indicating stable system operation is determined not to be present (e.g. it was determined that the system is not receiving organic material feed), the method proceeds by outputting said system state (see step S460 in Fig. 5) and ceasing determination of the presence of further system states in the hierarchical list. By way of example, in Figure 5, if it is determined that the system is not receiving organic material feed (i.e. a system state indicating stable operation is determined not to be present), the system state is output at S460 and no consideration is given to the system states that are lower in the hierarchical list of system states (i.e. S420 - S450). Similarly, where a system state indicating unstable system operation (e.g. a large spike in organic material loading rate) is determined to be present based on the obtained trends, the method proceeds by outputting said system state (see step S460 in Fig. 5) and ceasing determination of the presence of further system states in the hierarchical list. However, if a system state indicating unstable system operation (e.g. a large spike in organic material loading rate) is determined not to be present based on the obtained trends, the determination proceeds to the next system state (see arrow from S420 to S430 in Fig. 5 where ‘check for large spike in organic material loading rate’ is answered ‘NO’).

[0130] By monitoring the operational performance of the bio-electrochemical reactor system according to the above method, it is possible to identify the presence of system states that are most significantly impacting the stable operation of the bio-electrochemical reactor system with reduced information processing (e.g. in faster time and / or with fewer resources), as the hierarchical ordering of the system states means that the presence (or absence) of system states less significant to stable operation is only determined after the presence (or absence) of system states more significant to stable operation have been determined, and as soon as a system state indicating unstable system operation is determined to be present or a system state indicating stable operation is determined to be absent, this system state is output and no determination of the presence of further system states of lesser significance is made.

[0131] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function,8911901

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[0133] or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0134] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0135] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0136] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0137] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0138] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

891190121Claims:

1. A method of determining operational performance of a bioreactor system, the method comprising: obtaining one or more trends in data related to operation of the bioreactor system; and determining whether a system state indicating unstable system operation is present and / or a system state indicating stable operation is absent based on the one or more trends, wherein said determination is made by:obtaining a hierarchical list of system states;sequentially determining, in the order of said hierarchical list, whether or not a system state of said list is present based on the one or more trends and whether or not that system state indicates unstable system operation or stable system operation; andwhere a system state indicating unstable system operation is determined to be present, or a system state indicating stable operation is determined not to be present, outputting said system state and ceasing determination of the presence of further system states in said hierarchical list.

2. The method according to claim 1 , wherein the one or more trends are obtained by:obtaining data related to operation of the bioreactor system from a sensor;extracting one or more features from the data; andidentifying one or more trends in the data from the one or more features.

3. The method according to claim 1 or 2, wherein the bioreactor system is according to any one of claims 11 to 19.

4. The method according to claim 3, wherein the data related to operation of the bioreactor system comprises the current data for the subsets of the electrode pairs.

5. The method according to any one of claims 1 to 4, wherein the hierarchical list system states includes one or more of:whether or not the system is receiving an organic material feed;whether or not a spike in the organic material loading rate is present;whether or not the system is recovering from a downtime period;whether or not the system would provide a stable response to a potential organic material loading rate increase; andwhether or not the system would provide a stable response to a potential organic material loading rate decrease.

6. The method according to any one of claims 1 to 5, wherein the method further comprises:identifying one or more action states for operation of the bioreactor system based on the system state indicating unstable system operation identified as being present; andoptionally, operating the bioreactor system according to said one or more action states.8911901227. The method according to claim 6, wherein the one or more action states include one or more of: determining if a control system of the bioreactor system is operating properly;determining if one or more feed pumps are operating properly;controlling a control variable of the bioreactor system;pausing feeding to system;conducting offline analysis;determining a cause of a downtime period;requesting human operator intervention;requesting human operator monitoring;adjusting organic material loading rate; andcontrolling a voltage applied between a pair of electrodes.

8. The method of any one of claims 1 to 7, wherein hierarchical list may be in order of decreasing significance of impact of the system state on the operational stability of the bioreactor system9. The method of any one of claims 1 to 8, wherein the method is a computer-implemented method.

10. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to carry out the method of claim 9.

11. A bioreactor system comprising:a bioreactor vessel;an electrode system, the electrode system comprising:a plurality of electrode pairs spaced apart in the bioreactor vessel;an electrical circuit configured to apply, to each electrodes pair, a voltage between the electrode pair; andfor each of three or more subsets of the electrode pairs, a corresponding sensor configured to determine current data for the subset of the electrode pairs.

12. The bioreactor system according to claim 11, wherein:the bioreactor vessel comprises an inlet and an outlet, a downstream direction extending from the inlet to the outlet; andthe electrode system comprises:a first subset of the electrode pairs having a corresponding sensor configured to determine current data for the first subset, the first subset positioned adjacent the inlet;a second subset of the electrode pairs having a corresponding sensor configured to determine current data for the second subset, the second subset positioned downstream of the first subset; anda third subset of the electrode pairs having a corresponding sensor configured to determine current data for the third subset, the third subset positioned downstream of the second subset.89119012313. The bioreactor system according to claim 11 or 12, wherein one or more subsets of the electrode pairs is independently addressable to apply a voltage between the one or more electrode pairs of the subset.

14. The bioreactor system according to claim 13, wherein one or more subsets of the electrode pairs that is independently addressable to apply a voltage between the one or more electrode pairs of said subset has a corresponding sensor configured to determine current data for said subset.

15. The bioreactor system according to any one of claims 11 to 14, wherein the system further comprises one or more additional sensors configured to determine operational data of the system.

16. The bioreactor system according to claim 15, wherein the system further comprises one or more of:a gas outlet from the bioreactor vessel and an additional sensor configured to determine gas flow data for the gas outlet and / or an additional sensor configured to determine gas composition data for the gas outlet;an additional sensor configured to determine temperature data for the bioreactor vessel; an additional sensor configured to determine pH data for the bioreactor vessel;an additional sensor configured to determine organic material loading rata data;for one or more subsets of the electrode pairs, a corresponding additional sensor configured to determine voltage data for the subset of the electrode pairs;an additional sensor configured to determine liquid turbidity data;an additional sensor configured to determine volatile fatty acid concentration data;an additional sensor configured to determine chemical oxygen demand data; and / or an additional sensor configured to determine biochemical oxygen demand data.

17. The bioreactor system according to any one of claims 11 to 16, wherein the bio-electrochemical reactor system is configured for anaerobic digestion of organic material in the bioreactor vessel for the production of biogas.

18. The bioreactor system according to claim 17, wherein the bioreactor system is configured for electromethanogenesis.

19. The bioreactor system according to any one of claims 11 to 18, wherein the electrode system is configured for microbial electrolysis.

20. An electrode system for a bioreactor system, the electrode system comprising:a plurality of electrode pairs;an electrical circuit configured to apply, to each electrodes pair, a voltage between the electrode pair; andfor each of three or more subsets of the electrode pairs, a sensor configured to determine current data for the subset of the electrode pairs.89119012421. The electrode system according to claim 20, wherein one or more subsets of the electrode pairs is independently addressable to apply a voltage between the one or more electrode pairs of the subset.

22. The electrode system according to claim 21, wherein one or more subsets of the electrode pairs that is independently addressable to apply a voltage between the one or more electrode pairs of said subset has a corresponding sensor configured to determine current data for said subset.

23. The electrode system according to any one of claims 20 to 22, wherein the electrode system further comprises, for one or more subsets of the electrode pairs, a corresponding sensor configured to determine voltage data for the subset of the electrode pairs.

24. The electrode system according to any one of claims 20 to 23, wherein the electrode system is configured for microbial electrolysis.

25. The electrode system according to any one of claims 20 to 24, wherein the electrode system is configured for electromethanogenesis.

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