RESUMEN
This work characterizes and comparatively assess two cation exchange membranes (PSEBS SU22 and CF22 R14) and one bipolar membrane (FBM) in microbial electrolysis cells (MEC), fed either by acetate or the mixture of volatile fatty acids as substrates. The PSEBS SU22 is a new, patent-pending material, while the CF22 R14 and FBM are developmental and commercialized products. Based on the various MEC performance measures, membranes were ranked by the EXPROM-2 method to reveal which of the polymeric membranes could be more beneficial from a complex, H2 production efficiency viewpoint. It turned out that the substrate-type influenced the application potential of the membranes. Still, in total, the PSEBS SU22 was found competitive with the other alternative materials. The evaluation of MEC was also supported by analyzing anodic biofilms following electroactive bacteria's development over time.
Asunto(s)
Fuentes de Energía Bioeléctrica , Electrodos , Electrólisis , Ácidos Grasos Volátiles , Hidrógeno , Intercambio IónicoRESUMEN
In this work, two commercialized anion-exchange membranes (AEMs), AMI-7001 and AF49R27, were applied in microbial electrolysis cells (MECs) and compared with a novel AEM (PSEBS CM DBC, functionalized with 1,4-diazabicyclo[2.2.2]octane) to produce biohydrogen. The evaluation regarding the effect of using different AEMs was carried out using simple (acetate) and complex (mixture of acetate, butyrate and propionate to mimic dark fermentation effluent) substrates. The MECs equipped with various AEMs were assessed based on their electrochemical efficiencies, H2 generation capacities and the composition of anodic biofilm communities. pH imbalances, ionic losses and cathodic overpotentials were taken into consideration together with changes to substantial AEM properties (particularly ion-exchange capacity, ionic conductivity, area- and specific resistances) before and after AEMs were applied in the process to describe their potential impact on the behavior of MECs. It was concluded that the MECs which employed the PSEBS CM DBC membrane provided the highest H2 yield and lowest internal losses compared to the two other separators. Therefore, it has the potential to improve MECs.
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Fuentes de Energía Bioeléctrica , Geobacter/metabolismo , Hidrógeno/metabolismo , Membranas Artificiales , Piperazinas/química , Compuestos de Amonio Cuaternario/química , Aniones/química , Fuentes de Energía Bioeléctrica/microbiología , Electrólisis , Diseño de Equipo , Estudios de FactibilidadRESUMEN
This work assessed the feasibility of a hydrogenotrophic biogas process integrated with a membrane module in the external-loop design. The major scope was to conduct the investigation from the perspective of the membrane unit and reveal how the operating strategy influences the efficiency of biogas formation. It was observed that the fermenter worked with an improved efficacy, indicated by the higher concentration of methane in the headspace (80-90%) when the gas loading intensity, defined as the ratio of inlet gas permeation rate and the circulation rate of the liquid phase, was adjusted to lower values (3-5.3×10-3). Such results are implying that the mass transfer of H2 into the reactor is dependent on this critical parameter. Moreover, attention should be paid to the fouling of the module under longer-term experiments to keep its performance at a sufficient level.
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Biocombustibles , Metano , Anaerobiosis , Reactores Biológicos , HidrógenoRESUMEN
In this study single-chamber microbial electrolysis cells (MECs) were applied to treat cheese whey (CW), an industrial by-product, and recover H2 gas. Firstly, this 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 bioelectrohydrogenesis 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 bioelectrochemically. 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 behavior was attained using the effluent of the methanogenic reactor and therefore, considering a two-stage system, methanogenesis is an advisable pretreatment step for the acidic CW to enhance the H2 formation in complementary microbial electrohydrogenesis.
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Fuentes de Energía Bioeléctrica/microbiología , Queso , Electrólisis/métodos , Hidrógeno/metabolismo , Metano/biosíntesis , Suero Lácteo/química , Reactores Biológicos/microbiología , Ácidos Grasos Volátiles/metabolismo , Metano/análisisRESUMEN
In this work we report on the hydrogen production capacity of single-chamber microbial electrohydrogenesis cell (MEC) with optimized design characteristics, in particular cathode surface area and anode-cathode spacing using acetate as substrate. The results showed that the maximal H2 production rates and best energetic performances could be obtained using the smallest, 71 cm2 stainless steel cathode and 4 cm electrode distances, employing a 60 cm2 bioanode. Cyclic voltammetric analysis was employed to investigate the dominant electron transfer mechanism of the architecturally optimized system.