Bioelectrochemical enhancement of methane production from exhausted vine shoot fermentation broth by integration of MEC with anaerobic digestion
Daniela Carrillo‐Peña, Adrián Escapa, María Hijosa‐Valsero, Ana I. Paniagua-García, Rebeca Díez-Antolínez, Raúl Mateos
Abstract
Abstract A microbial electrolysis cell integrated in an anaerobic digestion system (MEC-AD) is an efficient configuration to produce methane from an exhausted vine shoot fermentation broth (EVS). The cell worked in a single-chamber two-electrode configuration at an applied potential of 1 V with a feeding ratio of 30/70 (30% EVS to 70% synthetic medium). In addition, an identical cell operated in an open circuit was used as a control reactor. Experimental results showed similar behavior in terms of carbon removal (70–76%), while the specific averaged methane production from cycle 7 was more stable and higher in the connected cell (MEC AD ) compared with the unpolarized one (OC AD ) accounting for 403.7 ± 33.6 L CH 4 ·kg VS −1 and 121.3 ± 49.7 L CH 4 ·kg VS −1 , respectively. In addition, electrochemical impedance spectroscopy revealed that the electrical capacitance of the bioanode in MEC AD was twice the capacitance shown by OC AD . The bacterial community in both cells was similar but a clear adaptation of Methanosarcina Archaea was exhibited in MEC AD , which could explain the increased yields in CH 4 production. In summary, the results reported here confirm the advantages of integrating MEC-AD for the treatment of real organic liquid waste instead of traditional AD treatment.