Synergistic Effect of Magnetite and Bioelectrochemical Systems on Anaerobic Digestion

Abstract

Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.

Effect of an Electromagnetic Field on Anaerobic Digestion: Comparing an Electromagnetic System (ES), a Microbial Electrolysis System (MEC), and a Control with No External Force

“…It was found that the MEC had the highest removal values for COD (98.6%), TOC (95.9%), TSS (88.4%), phosphate (76.3%), and NH 3 -N (43.7%). This can be attributed to the higher electron recovery efficiencies of the MEC system, namely the maximum current density (23.3 mA/m 2 ), coulombic efficiency (110.4%), and electrical conductivity (180 µS/cm) [ 22 , 23 , 48 , 49 ]. Conversely, exposure to electromagnetism (the ES) resulted in better removal of color (97.9%).…”

“…Bioelectrochemical systems (the MFC and the MEC) and electromagnetic systems are the most-used electromagnetic field systems in anaerobic digestion [ 21 , 22 ]. Madondo et al [ 23 ] reported that the most promising bioelectrochemical system is the MEC with 79.1% CH4 removal and 91.6% COD removal from sewage sludge. The MEC was also better in terms of electrochemical measurements, with a maximum current density of 23.3 mA/m 2 , an electrochemical methane yield of 153.44%, and a heterotrophic methane yield of 123.48%, and electrical conductivity of 269.7 µS/cm.…”

Electro-polarization of protein-like substances accelerates trans-cell-wall electron transfer in microbial extracellular respiration

“…Electro-activity of the microbial community has been regarded as the indicator to evaluate the EET of microbial aggregates. 16 The increase in the sludge electro-activity has been extensively reported in the EET-related processes including BESs, 17 direct interspecies electron transfer, 18 Feammox, 19 and so forth. The similarity of these systems is that the conductivity and capacitance of microbial aggregates were frequently found to increase with the operation.…”

Biophotocatalytic Reduction of CO2 in Anaerobic Biogas Produced from Wastewater Treatment Using an Integrated System

“…Moreover, variations in the AD process feedstock and environmental conditions can result in high complex sludge that is difficult to treat economically and environmentally [9,12,19]. On this basis, our previous work [17,20,21] and other researched studies [9,12,18,19,[22][23][24] show that using a photocatalyst (Fe-TiO 2 ) with magnetic properties has tremendous potential in wastewater settings. With this, and the need to meet future water demands, creating a cost-effective, user-friendly and reliable technology with a significant impact on energy production and recuperation in water settings is urgently needed [3,5,15,16].…”