A side-by-side comparison of two systems of sequencing coupled reactors for anaerobic digestion of the organic fraction of municipal solid waste

The objective of this work was to compare the performance of two laboratory-scale, mesophilic systems aiming at the anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW). The first system consisted of two coupled reactors packed with OFMSW (PBR1.1-PBR1.2) and the second system consisted of an upflow anaerobic sludge bed reactor (UASB) coupled to a packed reactor (UASB2.1-PBR2.2). For the start-up phase, both reactors PBR 1.1 and the UASB 2.1 (also called leading reactors) were inoculated with a mixture of non-anaerobic inocula and worked with leachate and effluent full recirculation, respectively. Once a full methanogenic regime was achieved in the leading reactors, their effluents were fed to the fresh-packed reactors PBR1.2 and PBR2.2, respectively. The leading PBR 1.1 reached its full methanogenic regime after 118 days (T m, time to achieve methanogenesis) whereas the other leading UASB 2.1 reactor reached its full methanogenesis regime after only 34 days. After coupling the leading reactors to the corresponding packed reactors, it was found that both coupled anaerobic systems showed similar performances regarding the degradation of the OFMSW. Removal efficiencies of volatile solids and cellulose and the methane pseudo-yield were 85.95%, 80.88% and 0.109 NL CH4 g-1 VSfed in the PBR-PBR system; and 88.75%, 82.61% and 0.115 NL CH4 g-1 VSfed in the UASB-PBR system [NL, normalized litre (273oK, 1 ata basis)]. Yet, the second system UASB-PBR system showed a faster overall start-up

Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

This work has been focused on the synthesis and characterization of different blended membranes SPEEK-35PVA (Water), SPEEK-35PVA (DMAc) prepared by casting and nanofiber-reinforced proton exchange membranes Nafion-PVA-15, Nafion-PVA-23 and SPEEK/PVA-PVB. The two first reinforced membranes were made up of Nafion (R) polymer deposited between polyvinyl alcohol (PVA) nanofibers. The last composite membrane is considered because the PVA is a hydrophilic polymer which forms homogeneous blends with SPEEK suitable to obtain high proton conductivity, while the hydrophobic PVB can produce blends in a phase separation morphology in which very low water uptake can be found. The synthesized membranes showed an outstanding stability, high proton conductivity, and enhanced mechanical and barrier properties. The membranes were characterized in single chamber microbial fuel cells (SCMFCs) using electrochemically enriched high sodic saline hybrid H-inocula (Geobacter metallireducen, Desulfurivibrio alkaliphilus, and Marinobacter adhaerens) as biocatalyst. The best performance was obtained with Nafion-PVA-15 membrane, which achieved a maximum power density of 1053 mW/m(3) at a cell voltage of 340 mV and displayed the lowest total internal resistance (Rint approximate to 522 Omega). This result is in agreement with the low oxygen permeability and the moderate conductivity found in this kind of membranes. These results are encouraging towards obtaining high concentrated sodic saline model wastewater exploiting MFCs.The authors wish to thank SEP and CINVESTAV-IPN for granting a PhD fellowship to one of the authors (KSK). We gratefully acknowledge the financial support of the National Council of Science and Technology, CONACYT, under grant FOINS 75/2012 and the Ministry of Science and Innovation of Spain through the project SP-ENE-20120718 and Support Programme for Research and Development of the Polytechnic University of Valencia through the project ref. 24761. Dr O. Solorza thanks Plan de Movilidad e Internalizacion Academica VLC/CAMPUS fellowship at the Universidad Politecnica de Valencia.Kamaraj, S.; Mollá Romano, S.; Compañ Moreno, V.; Poggi-Varaldo, HM.; Solorza-Feria, O. (2015). Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells. Electrochimica Acta. 176:555-566. doi:10.1016/j.electacta.2015.07.042S55556617

Biotechnology and Engineering Advances 2016

Fil: Candal, Roberto Jorge. Universidad Nacional de San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Curutchet, Gustavo Andres. Universidad Nacional de San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dominguez Montero, L.. No especifíca;Fil: Macarie, H.. No especifíca;Fil: Poggi, Varaldo, H.. No especifíca;Fil: Sastre, I.. No especifíca;Fil: Vazquez, S.. Universidad de Buenos Aires; Argentin

The effect of the supplementation with a primary carbon source on the resistance to oxygen exposure of methanogenic sludge

International audienceAnaerobic methanogenic consortia have a considerable resistance to oxygen exposure. Yet, most research has been focused on the study of the tolerance to oxygen of anaerobic immobilized biomass. Less is known on the potential of the anaerobic suspended biomass for withstanding exposure to oxygen and the effect of a primary degradable substrate on such resistance. Thus, the objective of this work was to determine the effect of the amount of a primary degradable substrate (sucrose) on the resistance of a methanogenic suspended biomass to oxygen exposure. It was found that the inhibition of disperse anaerobic sludge by oxygen exposure decreases when the concentration of the supplemented carbon source increases. This is in agreement with the fact that aerobic respiration of the added substrate by the facultative heterotrophic bacteria, always present in this type of sludge, has been found in previous studies as one of the main mechanisms protecting methanogens against O 2. From a practical point of view, this suggests that aeration of anaerobic systems should be possible without inhibiting the activity of methanogenic bacteria if an adequate ratio between oxygen and COD feeding is maintained. Such a ratio will depend however on the wastewater initial COD concentration