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Escamilla-Alvarado C.,Environmental Biotechnology and Renewable Energies RandD Group | Rios-Leal E.,CINVESTAV | Ponce-Noyola M.T.,Microbial Genetics Group | Poggi-Varaldo H.M.,Environmental Biotechnology and Renewable Energies RandD Group
Process Biochemistry | Year: 2012

The objective of this work was to evaluate the performance of a two-stage hydrogenogenic-methanogenic (H-M) semi-continuous process in terms of mass retention time (MRT) for hydrogenogenic stage (H-stage), feed source for methanogenic stage (M-stage) and thermal regime (35 and 55 °C) for both stages. The substrate was a model organic fraction of municipal solid wastes (OFMSW) at 35% total solids. In H-stage, mesophilic temperature had a positive significant effect on higher hydrogen productivities and lower amounts of hydrogen sinks compared to thermophilic operation. Calculations based on mass balances and biochemical stoichiometry confirmed that acid fermentation deviation was linked to low biohydrogen yields. The M-stage performance was influenced by both the temperature and feed source. Bioreactors in thermophilic regime performed better than mesophilic ones. Maximum methane productivity was 341 NmL CH4/(kgwmr d) that corresponded to the thermophilic bioreactor fed with fermented solids from H stage at 14 d MRT. The two-stage process showed higher gross energetic potential when compared to an only methanogenic process operated at equivalent MRT (control); this was due to a higher methane productivity in the M-stage of the series process. The main contribution of H-stage seemed to be associated to hydrolysis of the complex substrate thus generating metabolites for the M-stage rather than the hydrogen production itself. © 2012 Elsevier Ltd. All rights reserved. Source


Vazquez-Larios A.L.,Environmental Biotechnology and Renewable Energies RandD Group | Solorza-Feria O.,CINVESTAV | Vazquez-Huerta G.,CINVESTAV | Rios-Leal E.,Environmental Biotechnology and Renewable Energies RandD Group | And 2 more authors.
Journal of New Materials for Electrochemical Systems | Year: 2011

The objectives of this work were (i) to determine the effect of electrode spacing and architecture of microbial fuel cells (MFCs) on their internal resistance (Rint) using two methods (polarization curve, PolC, and impedance spectroscopy, IS); and (ii) to evaluate the effect of operation temperature (35 and 23°C) of MFCs on their internal resistance and performance during batch operation. Two types of MFCs were built: MFC-A was a new design with extended electrode surface (larger ξ, specific surface or surface area of electrode to cell volume) and the assemblage or "sandwich" arrangement of the anode-PEM-cathode (AMC arrangement), and a standard single chamber MFC-B with separated electrodes. In a first experiment Rint of MFC-A was consistently lower than that of MFC-B at 23oC, irrespective of the method, indicating the advantage of the design A. Rint determined by the two methods agreed very well. The method based on IS provided more detailed data regarding resistance structure of the cells in only 10% of the time used by the PolC. Rint of MFC-A determined by PolC at 35oC resulted 65% lower than that of MFC-A. The effect of temperature on Rint was distinct, depending upon the type of cell; decrease of temperature was associated to an increase of Rint in cell A and an unexpected decrease in cell B. In a second experiment, the effect of temperature and cell configuration on cell batch performance was examined. Results showed that performance of MFC-A was significantly superior to that of MFC-B. Maximum volumetric power PV and anode density power PAn of the MFC-A were higher than those of the MFC-B (4.5 and 2.2 fold, respectively). The improvement in PV was ascribed to the combined effects of increased ? and decrease of Rint. In spite of opposing trends in cells' Rint, performance of both cells in terms of PV ave improved at ambient temperature; furthermore, MFC-A outcompeted the standard cell B at both temperatures tested. The use of the new cell A would translate into a significant advantage since the power associated to heating the cells at 35°C could be saved by operation at ambient temperature. © J. New Mat. Electrochem. Systems. Source


Ortega-Martinez A.C.,Environmental Biotechnology and Renewable Energies RandD Group | Juarez-Lopez K.,National Autonomous University of Mexico | Solorza-Feria O.,CINVESTAV | Ponce-Noyola M.T.,Microbial Genetic Group | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2013

This work had a double purpose: (i) to study the effect of sulphate-reducing (SR-In) and enriched (E-In) inocula on the characteristics of one-chamber standard microbial fuel cell (MFC-S) and parallelepiped cell and (ii) to analyze the bacterial communities in cells operated with either SR-In or E-In. The MFC-S of 150 mL consisted of one-chamber plexiglass cell with electrodes separated 7.8 cm. The MFC-P consisted of a parallelepiped built in plexiglass with a liquid volume of 270 mL. Five faces of this cell were fitted with 'sandwich' cathode-membrane-anode assemblages (CMA). The values of internal resistance (Rint) were 4602 and 687 Ω, for the MFC-S loaded with SR-In and E-In, respectively. The values of Rint were 400 and 84, and 292 and 80 Ω for the faces connected in series and parallel and the MFC-P loaded with SR-In and E-In, respectively. Parallel connection of cell faces also significantly improved the electrochemical characteristics of the P cell (higher powers). In general, use of E-In in both types of MFC lead to improved power densities compared to SR-In. Molecular biology analysis of microbial communities showed that the E-In was less diverse than SR-In (in terms of phyla). An electrochemically active bacterium Geovibrio ferrireducens belonging to phylum Deferribacteres was found in the E-In. Predominance of Deferribacteres was observed in the E-In. Members of this phylum were not found in the SR-In. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Escamilla-Alvarado C.,Environmental Biotechnology and Renewable Energies RandD Group | Ponce-Noyola M.T.,Microbial Genetics Group | Poggi-Varaldo H.M.,Environmental Biotechnology and Renewable Energies RandD Group | Rios-Leal E.,CINVESTAV | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2014

Biohydrogen production has been coupled in some cases to other energy production technologies in order to overcome its modest energy gains. Anaerobic digestion, when used for methane recovery, has long been regarded as an energy recovery technology. We determined the energy potential from the coupling of either semi-continuous or batch hydrogen lab-scale bioreactors to a methanogenic stage. All processes were performed in solid substrate fermentation mode using the organic fraction of municipal solid wastes as first fed. Semi-continuous reactors for hydrogen production, operated at 20.9% total solids, 21 d mass retention time and 55 °C, averaged 202 NmL H2/kgrwm/d. In the batch hydrogen stage at 20.9% total solids, 50 h fermentation time and 55 °C, the hydrogen yield was 1200 mmol H2/kgVS and initial hydrogenogenesis rate was 68.3 mmolH2/kgvs/h. The methanogenic stage in semi-continuous performance at 18.4% total solids, 28 d mass retention time and 55 °C produced 2023 NmL CH4/kgrwm/d. Resultant energetic potentials (ÊP) were calculated from the theoretical combustion of the total hydrogen or methane produced by all the substrate fed to the process. ÊP for semi-continuous and batch hydrogenogenesis were 256 and 271 kJ/kgdb, whereas for the methanogenic stage was 11,889 kJ/kgdb. Correspondingly, energetic fluxes (EF) were calculated from the theoretical combustion of the hydrogen or methane productivities. The EF for semi-continuous and batch hydrogenogenesis were 2.55 and 24.1 kJ/kgrwm/d, whereas for the methanogenic stage was 80.3 kJ/kgrwm/d. Indeed, coupling of the methanogenic stage to either semi-continuous or batch hydrogenogenesis increased their energetic potentials by 4600 and 4300%. These results showed the clear advantage of the methanogenesis coupling in order to yield high energetic potentials from wastes. © 2014 Hydrogen Energy Publications, LLC. Source


Escamilla-Alvarado C.,Environmental Biotechnology and Renewable Energies RandD Group | Poggi-Varaldo H.M.,Environmental Biotechnology and Renewable Energies RandD Group | Ponce-Noyola M.T.,Microbial Genetics Group
Waste Management and Research | Year: 2013

We evaluated the production of holocellulases from the cellulolytic microorganisms Cellulomonas flavigena PR-22 and Trichoderma reesei MCG 80 using as substrates the organic fraction of municipal solid waste (OFMSW) and digestates from a hydrogenogenic-methanogenic bioenergy production process. The first set of experiments (E1) used the mutant actinobacteria C. flavigena PR-22 whereas another set (E2) used the mutant filamentous fungi T. reesei MCG 80. In E1 with OFMSW as substrate, xylanolytic activities ranged from 1800 to 3900 international units gholocellulose -1 (IUg hol -1), whereas the cellulolytic activities ranged from 220 to 420 IUghol -1. The variation of agitation speed did not have a significant effect on enzyme activity, whereas the increase of substrate concentration had a significant negative effect on both xylanolytic and cellulolytic activities on a holocellulose feed basis. Regarding E2, the OFMSW was evaluated at 1, 2 and 3 % volatile solids (VS). At 2 % VS the best filter paper activities were 1200 filter paper units (FPU) l-1; however, in a holocellulase basis the best result was 67 FPU ghol -1 corresponding to 1 % VS. Next, OFMSW was compared with OFMSW supplemented with lactose, digested solids from hydrogenogenic fermentation (D1) and digested solids from a two-stage process (D2). Against expectations, no positive effect was found in OFMSW due to lactose. The best enzymatic titres were in the order D1 > OFMSW ≈ OFMSW + lactose > D2. The use of digestates from hydrogenogenic fermentation for enzyme production holds promise for waste management. It promotes energy and added-value bioproduct generation - a green alternative to common practice of management and disposal of organic wastes. © 2013 The Author(s). Source

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