Microbial-BIO-electrochemical reactor (m-BEC) for enhanced BIO- h 2 production

Abstract

The present invention relates to a Microbial-bio-electrochemical reactor (M-BEC) for enhanced bio-H2 production. More particularly, the present invention relates to a reactor for the removal of biodegradable contaminants from wastewater using biological processes. The developed system is intrinsically coupled the dark fermentation with microbial-electrochemical process together into a next generation bio-reactor which employs biocatalyst to convert chemical energy stored in organics to hydrogen energy. The coupled M-BEC technology has developed to aimed towards the enhancement of the metabolic activity of electrochemically active biocatalyst by supplying organic / inorganic nutrients, electron acceptors, or donors, which felicitate the electro-hydrogenesis in a membrane less single cell reactor for bio- Hydrogen (green H2) production. The present invention also relates to a process for treatment of contaminated water which contains a large amount of biodegradable suspended solids and high concentrations of BOD and COD and enables bio-hydrogen generation with simultaneous removal of biodegradable TSS from wastewater.

Description

[0001] MICROBIAL-BIO-ELECTROCHEMICAL REACTOR (M-BEC) FOR ENHANCED BIO- H2PRODUCTION

[0002] FIELD OF INVENTION

[0003] The present invention relates to a modular reactor system for onsite bio-Hydrogen production and simultaneous wastewater treatment.

[0004] Immense increase in universal demand for energy requirement has been observed in recent days. Fossil fuels are the major global energy resource but they cause environmental problems during combustion. Depleting fossil fuel reserves, high-cost fluctuations, and consequential environmental effects have urged the need for alternative energy resources development. With reference to high efficiency, easy production, and pollution-free operation, biofuels are considered to be prospective and sustainable energy choice. Among various biofuels, biohydrogen has acquired greater attention owing to zero greenhouse gas emissions relative to other fuels. Hydrogen is a promising energy alternative because it is clean, renewable and has a high energy yield of 122 kJ / g. This yield is 2.75-fold greater than that from hydrocarbon fuels. At present, hydrogen is produced mainly from fossil fuels, biomass and water using chemical or biological processes. Biological hydrogen production processes have the advantages of being less energy intensive. The present invention shall help meet the 7thand 13thsustainable developmental goal of affordable clean energy and climate action.

[0005] BACKGROUND OF THE INVENTION

[0006] In an era of increasing energy costs and environmental awareness, wastewater treatment industries need to look at alternative treatment options to reduce their net energy expenditure. It has been estimated that domestic wastewater alone may contain 17.8 kJ / g of chemical oxygen demand (COD) of energy. There is an increasingly urgent need to recover some of this energy, or at the very least not expend additional energy on treatment; the activated sludge process uses 2.5-7.2 kJ / gCOD. Energy recovery could be achieved through innovative technologies by which one directly gets clean bio-energy (bio -hydrogen). The life cycle assessment has shown that the production of higher value products through the suite of integrated Bio-electrochemical systems (BES) may be the most viable solution.

[0007] H2produced from biological sources is known as bio-hydrogen. Biohydrogen is produced from different organic wastes. Biohydrogen is worldwide considered as one of the most promising alternatives to substitute fossil fuels in a near future. Indeed, hydrogen is not only characterized by its high density of energy (123-2.75 kJ / g), but also the efficiency of its conversion to electric energy is relatively high, and its utilization does not generate any greenhouse gases. Biohydrogen production has attracted worldwide attention because of its potential to become an inexhaustible, low-cost, and renewable source of clean energy. Currently, besides hydrogen production by water electrolysis based on renewable resources, the promising sectors of hydrogen production are those of biomass bio-refinery. Among diverse renewable biomass based tk-producing technologies, Dark Fermentation (DF) using anaerobic microbial communities, has gained increased attention not only because it achieves high H2 production rates, but also for its ability to produce Fh at low costs when degrading complex and unsterilized substrates such as waste. Among various organic-rich substrates, wastewaters and industrial by-products have gained a considerable attention due to their advantages such as high organic loads, low nutrient requirements and positive net energy gain. Particularly, wastewaters represent abundant, cheap and widely available sources of biodegradable substrates not yet exploited to produce bio-hydrogen by dark fermentation (DF)

[0008] Overall, in the world, the demand to energy is rapidly increasing. Furthermore, there are many countries which still depends on fossil fuel for energy generation but this source is not friendly to the environment due to a huge amount of CO2 generation during the conversion process. In addition, due to huge number of manufacturing units and with exponential growth of population enormous amount of wastewater is generated which needs extensive energy and huge cost for recycle and treatment. Due to shortage of energy, water crisis and climate change globally, the need of new sustainable energy technology is the need of the hour. In addition to this, there is a huge demand for generating energy from wastewater and reduce the operational costs.

[0009] Hydrogen gas shows great promise as a non-polluting fuel, but to reduce carbon dioxide releases hydrogen gas will need to be produced from renewable sources. Wastewaters have great potential for economical production of hydrogen. The technologies that remediate the pollutants can be divided into physicochemical and biological technologies. Physical technologies include washing by co-solvents, surfactants or reduction using chemical agents. The biological process utilizes the vast diversity of microbes to degrade organic / inorganic pollutants as a carbon energy source. These bio-electrochemical systems where carbon-rich waste is utilized as a substrate, releasing electrons (e ) and protons (H+) consequently generating bioelectricity. It is quite often inexpensive and assures the complete mineralization of pollutants. In this regard, the bio-electrochemical cells (BEC) were gaining attention due to their possibility in overcoming the limitations noted in aerobic systems and the physicochemical process. Bio-electrochemical systems (BESs) are characterized by the use of microorganisms for the generation of electricity by anodic and cathodic reactions within an electrochemical configuration, using the organic matter contained in the wastewater as a fuel source. According to Logan et al. (2015), the BESs have attracted interest in research, not only because of the worldwide trend in sustainable energy production, but also because these systems allow conducting other types of simultaneous operations to degrade organic matter and they also allow the bioremediation of polluted sites. Several bioprocesses have been investigated over the last decades to produce H2 through sustainable methods. Biological hydrogen production is also a promising technology for the future as it is considered a clean and renewable source and has the highest energy content per unit weight; 122-142 kJ / g, compared to any known fuel.

[0010] Reference may be made to a researcher (Hafez., 2013) discloses a hydrogen generation process and system which facilitates application of two processes for hydrogen production from organic material (for example industrial organic waste and biomass): dark fermentation and electro-assisted fermentation. Both dark fermentation and electro-assisted fermentation are applied in a single bioreactor, the method includes recovering at least a portion of the H2 and of the CO2 from the gravity settler. Accordingly to the detailed description of the invention, input voltage is applied to the gravity settler and the method includes recovering at least a portion of H2 and CO2 produced by electrohydrogenesis in the gravity settler. Further the temperature in the gravity settler is maintained at between about 20° C and about 70°C. Graphite brushes / Carbon cloth was used as anode. Carbon cloth Pt / C and stainless steel was used as cathode. Present innovation does not involve any precious metal as electrode material. Reference may be made to a group of researches (Lu et al., 2009) discloses a single-chamber microbial electrolysis cell (MEC) and demonstrates that additional hydrogen can be produced from the effluent of an ethanol-type dark-fermentation reactor. An overall hydrogen recovery of 83 ± 4% was obtained using a buffered effluent (pH 6.7-7.0), with a hydrogen production rate of 1.41 ± 0.08 m3 H2 / m3reactor / d, at an applied voltage of Eap= 0.6 V. Carbon fibre brush was used as anodes and carbon cloth coated with Pt (20 wt% Pt / C) was used a cathode. Limitation of the process was evolution of methane gas at higher applied voltages which could not be completely eliminated. Reference may be made to a group of researches (Rivera et al., 2017) discloses a singlechambered microbial electrolysis cell (MECs) to treat cheese whey (CW), an industrial byproduct, and recover H2 gas. According to the disclosure, the substrate was fed directly to the MEC to get the initial feedback about its H2 generation potential. The results indicated that the direct application of CW requires an adequate pH control to realize bio-electro hydrogenesis and avoid operational failure due to the loss of bioanode activity. In the second part of the study, the effluents of anaerobic (methanogenic) digester and hydrogenogenic (dark fermentative H2-producing) reactor utilizing the CW were tested in the MEC process (representing the concept of a two-stage technology). It turned out that the residue of the methanogenic reactor - with its relatively lower carbohydrate and higher volatile fatty acid contents was more suitable to produce hydrogen bio electrochemically. The MEC operated with the dark fermentation effluent, containing a high portion of carbohydrates and low amount of organic acids, produced significant amount of undesired methane simultaneously with H2. Overall, the best MEC behaviour was attained using the effluent of the methanogenic reactor and therefore, considering a two-stage system, methanogenesis is an advisable pre-treatment step for the acidic CW to enhance the H2 formation in complementary microbial electrohydrogenesis. It was reported that, the methane production was significant (45 vol.%), as compared to that of H2 (41 vol.%) and CO2 which is the major limitation of the process. Another drawback of the process was lower COD disintegration (-24-25%). Process does not involve any biocatalyst for enhancing the hydrogen production.

[0011] In conclusion, there is a need to produce hydrogen from wastewater in order to maximise resource utilisation, improve wastewater treatment procedures, produce clean energy, and support environmental sustainability. Present innovation is in line with the overarching objectives of shifting to a more efficient and circular economy.

[0012] Major problem in hydrogen production from wastewater is the presence of contaminants, such as organic substances and impurities, which can affect the efficiency of electrolysis process.

[0013] Membrane fouling and cost is a serious issue in electrolysis restrict its application. Energy- intensive electrolysis processes contribute to the high cost of green hydrogen. Present innovation involves an advanced bio-electro chemical process for simultaneous production of green hydrogen and treated water which improving the overall efficiency of hydrogen production. Innovative membrane less solar driven single cell M-BEC reactor was developed which contributes low process and operating cost. OBJECTIVES OF THE INVENTION

[0014] The main objective of the present invention is to provide sustainable Microbial-bio- electrochemical reactor (M-BEC) process for bio-hydrogen production.

[0015] Another objective of the present invention is to provide Microbial-bio-electrochemical reactor (M-BEC) for hydrogen production from liquid waste or effluent.

[0016] Still another objective of the present invention is to provide a membrane less single cell unit for bio-H2 production.

[0017] Yet another objective of the present invention is to provide a renewable energy based (solar) system that is modular, scalable, and low carbon footprint for operation.

[0018] Another objective of the present invention is to provide a renewable energy based integrated process for the treatment of organic-rich effluent / wastewater which is capable of recovering resources like bio-hydrogen, and VFA.

[0019] Yet another objective of the present invention is to provide a modular system for bio-hydrogen production utilizing high strength liquid effluent (high COD) from various sources.

[0020] Still another objective of the present invention is to provide a bio-catalyst for enhance biohydrogen production from effluent.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1. represents process flow diagram of Microbial-bio-electrochemical reactor (M-BEC) process where 1 represent DC power supply; 2 represent cathode; 3 represent anode; 4 represent reactor base platform; 5 represent pH adjustment vessel; 6 represent dosing pump; 7 represent pH sensor; 8 represent temperature sensor; 9 represent tubes for sampling port; 10 represent gas measuring system; 11 represent M-BEC reactor; 12 represent effluent drainage port ; 13 represent solar PV unit.

[0023] FIG. 2. represents a fully functional laboratory realization of a M-BEC reactor constructed using glass where 2 represent cathode; 3 represent anode; 14 represent reactor top lead; 15 represent port for temperature sensor; 16 represent port for gas tubes; 17 represent sampling port; 18 represent pH adjustment; 19 represent port for pH sensor; 20 represent housing for electrode module.

[0024] FIG. 3. represents an embodiment of an electrode module of M-BEC reactor.

[0025] FIG.4. represents hydrogen production pathways in anaerobic reaction condition in presence of anoxic microorganism.

[0026] SUMMARY OF THE INVENTION

[0027] The present invention provides a microbial-bio-electrochemical reactor system (11) for bio-H2 generation from liquid waste comprising:

[0028] (i) DC power supply (1),

[0029] (ii) reactor base platform (4),

[0030] (iii) pH adjustment vessel (5)

[0031] (iv) dosing pump (6),

[0032] (v) pH sensor (7), temperature sensor (8),

[0033] (vi) sampling port (9),

[0034] (vii) gas measuring system (10) and

[0035] (viii) a glass cylindrical M-BEC reactor (11),

[0036] (ix) effluent drainage port (12),

[0037] (x) solar PV unit (13).

[0038] In an embodiment of the present invention provides the glass cylindrical M-BEC reactor (11) further comprises a cathode (2), an anode (3), reactor top lead (15), port for temperature sensor (15), port for gas tubes (16), sampling port (17), pH adjustment (18), port for pH sensor (19), electrode module (20).

[0039] In another embodiment of the present invention provides the cathode and anode is made up of stainless- steel mesh and modified graphite rod respectively.

[0040] In yet another embodiment discloses the M-BEC reactor (11) facilitating a dark fermentation assisted electro-hydrogenesis process.

[0041] In another embodiment discloses the M-BEC reactor (11) is incubated in a thermostatic bath at a temperature range of about 35-40° C. In other embodiment discloses the M-BEC reactor (11) is operated with an input applied voltage in the range of 0.5V -1.5 V.

[0042] In yet other embodiment discloses the power required as input voltage is drawn from solar PV unit.

[0043] In yet other embodiment discloses the use of M-BEC reactor (11) in the generation of biohydrogen from the organic liquid waste with average hydrogen content of 58-64%.

[0044] In one of the embodiment discloses a process for the generation of bio-hydrogen using the microbial-bio-electrochemical reactor system (11) comprising:

[0045] (a) providing granular or flocculant anaerobic sludge;

[0046] (b) culturing a electrogenic H2 producing biocatalysts;

[0047] (c) inoculating the anaerobic sludge of step (a) and biocatalysts of step (b) in the M-BEC reactor (I D,

[0048] (d) accomplishing microbial electrolysis in the M-BEC reactor (11) of step (c) by hydrogen producing microorganisms to obtain a produced bio-hydrogen gas;

[0049] (e) collecting bio-hydrogen gas as obtained in step (d) in a gas storage vessel.

[0050] In another embodiment discloses the in-situ developed hydrogen producing exoelectrogenic microorganisms is identified which classified under Bacillus species.

[0051] In yet another embodiment discloses the bio-catalyst prepared from the activated sludge collected from a wastewater treatment plant.

[0052] DETAILED DESCRIPTION OF THE INVENTION

[0053] The invention is explained with respect to the drawing accompanying this specification. In the drawings many details pertaining to fabrication not bearing upon points of novelty are omitted in the interest of descriptive clarity. Functionally equivalent components are given identical reference numbers in the various drawings. These components are explained in detail for the first occurrence only for sake of brevity. The invention relates to a Microbial-bio-electrochemical reactor (M-BEC) for enhanced bio- H2 production from organic rich liquid waste and wastewater. The invention relates to the temperature-controlled M-BEC reactor comprises an electrode module, an external circuit and a load or an external power supply / solar driven, pH, and temperature, integrated gas flow meter with sampling port. The reactor can work as a microbial fuel battery or microbial-electro- chemical reactor for bio-H2 production from liquid waste.

[0054] Present innovation incorporated microbial electrohydrogensis coupled with anaerobic degradation (AD) in a single cell reactor. Fig 1 represented the developed bio-electrochemical (BEC) process as a whole. System comprised included a Base solution vessel (5), Pump (6) M- BEC reactor (11), magnetic stirrer (4), cathode (2), bio anode (3), pH meter (7), DC power supply (1), and sampling tube (9), temperature sensor (8), Gas Collector (10) and effluent discharge port (12).

[0055] The M-BEC is a glass reactor with a total liquid volume of approximately 3.0 1. The reactors is incubated in a thermostatic bath stabilizing at 40 °C. The reactor features a lid with several sampling ports. The lid is made of stainless steel, has a height of 1 cm and a diameter of 15 cm. The sampling ports are strategically designed for parameter control, ensuring continuous temperature maintenance, and facilitating gas collection. M-BEC was subjected to testing using a fixed ratio of bio-catalyst to feed stock over a certain period of time with an applied voltage of 0.9 V.

[0056] M-BEC anode and cathode configuration:

[0057] The anode was fabricated using a graphite rod with dimensions of 15 cm in length and 1 cm in diameter. Subsequently, it underwent acid-alkali treatment to modify as a bio-anode. As for the cathode, a stainless- steel plate (15 cm in length, and 4 cm in width) was employed. The utilization of both graphite and stainless steel aimed to ensure optimal conductivity between the electrodes. Stainless steel's lower electrical resistivity compared to graphite was exploited to diminish the overall ohmic resistance of the anode. Bio-anode and cathode were housed inside the reactor and connected with insulated wires to the electrical circuit. Bio-hydrogen produced in the reactor was collected in a gas storage vessel.

[0058] The developed M-BEC reactor comprises a cylindrical vessel made of glass with a flat bottom section, and tightly sealed top section. The top of the M-BEC is sealed for maintaining an anaerobic environment and covered with aluminium foil for maintaining dark fermentation at the same time. Slow mixing condition is achieved by incorporating a magnetic stirrer. For maintaining pH of the system, a dosing pump connected with acid / base vessel is integrated with the reactor. Electrode module is fixed at the top of the reactor. Modified graphite rod is used as bio-anode and stainless-steel mesh is used as cathode. The M-BEC is operated as a two-electrode membrane less bio -electrochemical cell. The effluent port is located at bottom part of the reactor.

[0059] FIG. 2 represents a fully functional laboratory realization of a single chamber M-BEC reactor constructed using glass. In actual construction of this laboratory realization of the invention, the reactor, is clamped together in leak tight manner using top lead (14). Electrode module (20) is attached at the top. The cell worked at a closed-circuit voltage, using an external resistance and DC power supply. DC power supply unit is connected with solar PV unit. Modified graphite was used as bio-anode and SS mesh was used as cathode. Temperature of the reactor is controlled by a heating plate attached at the bottom the reactor (4).

[0060] The reactor is filled with deoxygenated water. The reactor is provided with sufficient quantity of acclimatised seed sludge (i.e., anaerobic sludge), which may have granular or flocculant Settling characteristics. Specially cultured Exo-electrogenic H2 producing bio-catalysts are introduced in the reactor. Some part of soluble matter in the wastewater is converted to biohydrogen and carbon dioxide by elctro-hydrogenesis in presence of microbial action in the reactor. The produced gas is collected in gas space which exits through the nozzle to a constant pressure gas storage tank.

[0061] Another embodiment of the invention is the membrane less single cell M-BEC reactor. M-BEC is operated in a batch mode. The growth of biofilm and microbial consortia attached with electrode surface accelerated the degradation of suspended solid and dissolved organic matter. In-situ exoelectrogenic micro-organism grows on the electrode surface identified as Bacillus species which are temperature tolerant, spore forming Gram-positive bacteria. In-situ developed exoelectrogenic micro-organism helped to accomplish dark fermentation assisted elctro-hydrogenesis process.

[0062] EXAMPLE

[0063] The following examples are given by way of illustration only and therefore should not be construed to limit the scope of the present invention in any manner. Dark fermentation is a ubiquitous phenomenon under anaerobic conditions (i.e., no oxygen present as an electron receptor). When bacteria grow on organic substrates (heterotrophic growth), these substrates are degraded by oxidation to provide building blocks and metabolic energy for growth. This oxidation generates electrons which need to be disposed of to maintain electronic neutrality. In anaerobic environments, other compounds e.g., protons (H+), which are reduced to molecular hydrogen (H2), need to act as electron acceptors. In the Dark fermentation process of glucose (substrate) to hydrogen, pyruvate is a key anaerobic metabolite formed by glucose catabolism. The breakdown of pyruvate is catalysed by one of two enzyme systems:

[0064] (a) Pyruvate: formate lyase (PFL)

[0065] Pyruvate+ CoA Acetyl-CoA H — Formate (1)

[0066] (b) Pyruvate: ferredoxin oxidoreductase

[0067] Pyruvate +C0A+ 2Fd (ox)— Acetyl- CoA+COi+2Fd (red) (2)

[0068] As illustrated in Fig. 4, in the absence of oxygen, the pyruvate is used to produce acetyl CoA, from which ATP can be derived, and either formate or reduced ferredoxin, from which hydrogen can be derived by hydrogenase. The enteric bacteria derive hydrogen from formate by formate lyase and strict anaerobes derive hydrogen from Fd (red) by hydrogenase. Depending on the fermentation conditions and micro-organism used in the process, acetic and butyric acid are the main anaerobic metabolites along with hydrogen gas.

[0069] C6HI2O6+ 2H2O 2CH3COOH + 2CO2+ 4H2(3)

[0070] C6HI2O6+ 2H2O CH3CH2CH2COOH + 2CO2+ 2H2(4)

[0071] According to this reaction, only one-third of available electrons are utilized for hydrogen production. Different metabolic pathways are also used by bacteria that produce other volatile fatty acids (VFAs), reducing overall hydrogen yields. In order to further recover hydrogen from these fermentation end products an external energy must be supplied to make the reaction thermodynamically favorable in the presence of high concentrations of hydrogen. This energy can be provided by bio-electrochemical processes. In M-BEC the electrical voltage needed (0.110 V in theory, >0.2 V in practice) is significantly lower than the theoretical voltage needed for water electrolysis (1.8 V in practice). Bio-electrochemical degradation of acetate by exoelectrogens released H+and CO2 into electrolyte and e- to the anode as an oxidation half reaction in M-BEC reactor

[0072] Anode: CH3COOH + 2H2O 2CO2+ 8e + 8H+(5)

[0073] Cathode: 8H++ 8e 4H2(6)

[0074] The generated e“ flow through an external circuit to the cathode and H+diffuse across the electrolyte to the cathode where they reduce with e- by an extra applied voltage to form H2as the reduction half reaction and complete the circuit.

[0075] The conversion efficiency for hydrogen production was based on the maximum possible yield of four moles of H2produced per mole of carbohydrate with the assumption that glucose was the sole carbohydrate and the primary product is acetate. COD reduction was calculated from the amount of H2produced, or directly measured according to Standard Methods. The CODs of a gram of hydrogen and glucose are 8 g-COD / g-H2and 1.066 g-COD / g-glucose.

[0076] A modular, M-BEC reactor for bio-hydrogen production was fabricated based on the present invention. The reactor made of a glass reactor with 15 cm inner diameter, 24 cm in height, and a working volume of 3 1. Reactor was operated in batch mode under anaerobic conditions, at a temperature of 35-40°C and at a pH 5-6. Modified graphite was used as bio-anode and SS mesh was used as cathode. Reactor is worked as a single cell microbial bio-electrochemical hydrogen generator. The cell worked at a closed-circuit voltage, using an external resistance of 100 Q. Reactor was operated with and applied voltage of 0.5- 1.0 V through a DC power supply which is connected with the solar PV system.

[0077] Gas composition was analysed by a gas chromatograph (GC) (Perkin-Elmer, model Clams 580, USA) equipped with a thermal conductivity detector (TCD) and a micropackaged shincarbon column (2m length, 1 mm ID, 1 / 16" OD, 100 / 120 mesh). The temperatures of the column and the TCD detector were 150° C. and 250°C. Helium was used as the carrier gas at a flow rate of 10 ml / min. Volatile Fatty Acid (VFA) was analysised using a gas chromatograph (GC) (Perkin- Elmer, model Clams 580, USA) equipped with a split injector and a Flame Ionization Detector (FID). Separation of VFAs was achieved using a wax column (30 m length, 0.32 mm inner diameter, and 0.5 pm film thickness). The injector temperature was maintained at 200°C, and the detector was set at 250°C. Helium was used as the carrier gas at a flow rate of 8.0 mL / min and a pressure of 36.6 psi. Initial and final COD was measured according to standard methods using COD analyser (HI839800, Hanna Instrument). Example 1:

[0078] H2-producing bio-catalyst was prepared from the activated sludge obtained from a wastewater treatment plant (8°27'32.62"N and 76°56'15.08"E) located in Thiruvananthapuram, Kerala. Liquid bio-catalyst was prepared by cyclic treatment of acid-alkali, thermal and sonication. Prior to start-up, reactor was inoculated with anaerobic sludge and bio-catalyst. Biofilms rich in H2-producing exoelectrogenic microorganism were grown on the electrode surface at batch mode before the reactor was switched to an operating mode. Identified exoelectrogenic microorganisms present in the reactor were grouped under Bacillus species. The performance data of M-BEC reactor is summarized in Table 1. Microbial electrolysis is accomplished in an electrochemical reactor, with an anode at which organic substrates are microbially oxidized to provide an electric current that is then used at the cathode to electrochemically produce hydrogen from water.

[0079] Long-term operation (over 50 days) of the M-BEC reactor was conducted. Headspace volume of the reactor is 1 lit. The cumulative bio-H2 produced around 2.5 lit, with an average hydrogen content of 58-64 vol %.

[0080] Table 1: Performance details of a M-BEC reactor with biodegradable liquid waste as feedstock.

[0081] Parameters Values

[0082] Bio-H2Yield 27.30 mol H2 / kg of COD

[0083] Bio-H2 production 14.93 g / kg feedstock

[0084] Hydrogen production rate (HPR) 1.59-25.83 ml / d

[0085] Hydraulic retention time (HRT) 5.6-6 hr

[0086] Average COD disintegration 54.28 %

[0087] TN removal 53.0 %

[0088] VFA concentration Butyric acid 933.19 mg / 1

[0089] Valeric acid 138.45 mg / 1

[0090] Caproic acid 168.04 mg / 1

[0091] The above example 1 illustrates a system that can operated with liquid biodegradable waste with COD of around 7400 mg / 1. Example 2:

[0092] Similar experimental procedure and process condition as mentioned earlier was followed. Feedstock used for the example 2 was glucose. M-BEC reactor was operated for a period of 51 days. The cumulative bio-H2produced was around 2.4 lit. M-BEC reactor was operated with feedstock having average COD of 2400 mg / 1. The performance data of M-BEC reactor is summarized in Table 2.

[0093] Table 2: Performance details of a M-BEC reactor with standard carbon source (glucose) as feedstock.

[0094] Parameters Values

[0095] Bio-H2Yield 8.40 mol H2 / kg of COD

[0096] Bio-H2production 6.72 g / kg feedstock

[0097] Hydrogen production rate (HPR) 0.63 - 24.58 ml / d

[0098] Hydraulic retention time (HRT) 5.6-6 hr

[0099] COD disintegration 79.30 %.

[0100] TN removal 52.0 %

[0101] VFA concentration Butyric acid 403.48 mg / 1

[0102] Valeric acid 454.80 mg / 1

[0103] Acetic acid 456.30 mg / 1

[0104] Propionic acid 225.17 mg / 1

[0105] In- situ exoelectro genic activity of biofilm developed on the electrode surface was confirmed by chronaamperometry which was observed as 1.73xlO’3mA / cm2. The average hydrogen (H2) content in gas produced was 90 vol % followed by 9.08 vol % CO2 and 0.14 vol % H2S. Total energy efficiency of the process was estimated as 52.3% and average power density of the process is 13.59 KW / m3respectively.

[0106] ADVANTAGES OF THE INVENTION The developed M-BEC reactor converts chemical energy stored in organics to bio-H2 energy and simultaneous produce treated water. The developed system is a next generation bio -electrochemical reactor which combine the dark fermentation with microbial-electrochemical process together into a next generation bio -reactor. The developed M-BEC reactor is a two-electrode membrane less bio-electrochemical single cell reactor. Developed M-BEC Process is low operating and maintenance cost. It is a renewable energy based-solar driven sustainable process. It is a modular and scalable unit suitable for onsite bio-H2 generation and simultaneous treatment of wastewater. The developed M-BEC reactor converts 54-79% of the inlet COD into bio-H2.

[0107] Reference:

[0108] Hafez, H. M. (2013). Method and system for electro-assisted hydrogen production from organic material. US 2013 / 0217089 Al

[0109] Logan, B.E., Wallack, M.J., Kim, K.Y., He, W., Feng, Y., Saikaly, P.E. (2015). Assessment of microbial fuel cell configurations and power densities, Environmental Science & Technology Letters, 2, 206-214. Lu, L., Ren, N., Xing, D., Logan, B. E. (2009). Hydrogen production with effluent from an ethanol-H2-coproducing fermentation reactor using a single-chamber microbial electrolysis cell. Biosensors and Bioelectronics, 24(10), 3055-3060.

[0110] Rivera, I., Bakonyi, P., Cuautle-Marfn, M. A., Buitron, G. (2017). Evaluation of various cheese whey treatment scenarios in single-chamber microbial electrolysis cells for improved biohydrogen production. Chemosphere, 174, 253-259.

Claims

We Claim:

1. A microbial-bio-electrochemical reactor system (11) for bio-tk generation from liquid waste comprising:(i) DC power supply (1),(ii) reactor base platform (4),(iii) pH adjustment vessel (5)(iv) dosing pump (6),(v) pH sensor (7), temperature sensor (8),(vi) sampling port (9),(vii) gas measuring system (10) and(viii) a glass cylindrical M-BEC reactor (11),(ix) effluent drainage port (12),(x) solar PV unit (13).

2. The microbial-bio-electrochemical reactor system (11) as claimed in claim 1, wherein the glass cylindrical M-BEC reactor (11) further comprises a cathode (2), an anode (3), reactor top lead (15), port for temperature sensor (15), port for gas tubes (16), sampling port (17), pH adjustment (18), port for pH sensor (19), electrode module (20).

3. The microbial-bio-electrochemical reactor system (11) as claimed in claim 2, wherein the cathode and anode is made up of stainless-steel mesh and modified graphite rod respectively.

4. The microbial-bio-electrochemical reactor system (11) as claimed in claim 1, wherein M- BEC reactor (11) facilitating a dark fermentation assisted electro-hydrogenesis process.

5. The microbial-bio-electrochemical reactor system (11) as claimed in claim 1, wherein the M-BEC reactor (11) is incubated in a thermostatic bath at a temperature range of about 35-40°C.

6. The microbial-bio-electrochemical reactor system (11) as claimed in claim 1, wherein the M-BEC reactor (11) is operated with an input applied voltage in the range of 0.5V -1.5 V.

7. The microbial-bio-electrochemical reactor system (11) as claimed in claim 6, wherein the power required as input voltage is drawn from solar PV unit.

8. The microbial-bio-electrochemical reactor system (11) as claimed in claim 1, for use in the generation of bio-hydrogen from the organic liquid waste with average hydrogen content of 58-64 vol% whereas 90 vol% for glucose as a standard carbon source.

9. A process for the generation of bio-hydrogen using the microbial-bio-electrochemical reactor system (11) as claimed in claim 1 comprising:(a) providing granular or flocculant anaerobic sludge;(b) culturing a exo-electrogenic microorganism and H2 producing biocatalysts;(c) inoculating the anaerobic sludge of step (a) and biocatalysts of step (b) in the M-BEC reactor (I D,(d) accomplishing microbial electrolysis in the M-BEC reactor (11) of step (c) by in-situ hydrogen producing microorganisms to obtain a produced bio-hydrogen gas;(e) collecting bio-hydrogen gas as obtained in step (d) in a gas storage vessel.

10. The process as claimed in claim 9, wherein the in-situ grown exoelectrogenic producing microorganisms is were identified which belongs to Bacillus species which facilitated enhance bio-hydrogen production.

11. The process as claimed in claim 9, wherein the bio-catalyst is metal free carbon martial derived from activated sludge.

12. The process as claimed in claim 9, wherein the average COD removal is 79.3 % for glucose as a standard carbon source and 54.28 % for biodegradable liquid waste.

13. The process as claimed in claim 9, wherein breaking down the biodegradable organic material into major products including H2, and fatty acids.

14. The process as claimed in claim 9, wherein the process is the completely mixed bioreactor operating at 35-40 °C as a bio-electrohydrogenator.

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