Electrochemistry and microbiology of microbial fuel cells treating marine sediments polluted with heavy metals

Abstract

The industrial contamination of marine sediments with chromium, copper and nickel in Penang, Malaysia was addressed with bio-remediation, coupled with power generation, using in situ sediment microbial cells (SMFCs) under various conditions. The efficiency of aerated sediment microbial fuel cells (A-SMFCs) and non-aerated sediment microbial fuel cells (NA-SMFCs) was studied. The A-SMFCs generated a voltage of 580.5 mV between 50 and 60 days, while NA-SMFCs produced a voltage of 510 mV between 60 and 80 days. The cell design point for A-SMFCs was 2 kU, while for NA-SMFCs it was 200 U.In both SMFCs, the maximum current values relating to forward scanning, reverse scanning and oxidation/reduction peaks were recorded on the 80 th day. The anode showed maximum additional capacitance on the 80 th day (A-SMFC: 2.7 F cm À2; and NA-SMFC: 2.2 F cm À2). The whole cell electrochemical impedance using the Nyquist model was 21 U for A-SMFCs and 15 U for NA-SMFCs.After glucose enrichment, the impedance of A-SMFCs was 24.3 U and 14.6 U for NA-SMFCs. After 60 days, the A-SMFCs reduced the maximum amount of Cr(VI) to Cr(III) ions (80.70%) and Cu(II) to Cu(I) ions (72.72%), and showed maximum intracellular uptake of Ni(II) ions (80.37%); the optimum remediation efficiency of NA-SMFCs was after 80 days toward Cr(VI) ions (67.36%), Cu(II) ions (59.36%) and Ni(II) ions (52.74%). Both SMFCs showed highest heavy metal reduction and power generation at a pH of 7.0. SEM images and 16S rRNA gene analysis showed a diverse bacterial community in both A-SMFCs and NASMFCs. The performance of A-SMFCs showed that they could be exercised as durable and efficient technology for power production and the detoxification of heavy metal sediments. The NA-SMFCs could also be employed where anaerobic fermentation is required.

Insights into Advancements and Electrons Transfer Mechanisms of Electrogens in Benthic Microbial Fuel Cells

“…In the anodic chamber of BMFC, organic substrates are reduced by microbes and transfer electrons to anodes, from where the electrons move to the cathode through external circuit to generate electricity [ 27 ]. Earlier, the microbes were exploited in the anodic chamber, but recently microbes are also exploited as biocathodes in the cathodic region to assist electrons transmission to the terminal electron acceptor (TEA) [ 28 , 29 ]. The power density, current density and coulombic efficiency can be measured by electron transfer rate.…”

A state of the art review on electron transfer mechanisms, characteristics, applications and recent advancements in microbial fuel cells technology

“…The electrode is one of the primary components in MFC design, and it is the key factor that decides the cost and performance of MFC. Thus, the greatest challenge in making MFC technology scalable and cost effective is designing electrodes (42,43). A large number of electrode materials have been studied.…”

Effect of introduced‐electrode on phenanthrene degradation in the soil microbial electrochemical remediation

“…Microbial electrochemical technologies (MET), including the microbial fuel cell (MFC), the microbial electrolysis cell (MEC), microbial electrosynthesis (MES), and the microbial desalination cell (MDC), are prosperous and have been considerably developed in the water treatment field 3‐7 . Therein, the MFC has also been used in sediment, sludge, and soil remediation and has the advantage of degrading pollutants and simultaneously generating electricity 8‐12 . Particularly in soils contaminated by organics, electron acceptors are generally limited, and yet, soil microbial electrochemical remediation (MER), that is, soil MFC, provides an inexhaustible electron acceptor (solid anode) to oxidize organic pollutants 13‐19 …”