Horizontal arrangement of anodes of microbial fuel cells enhances remediation of petroleum hydrocarbon-contaminated soil

Abstract

With the aim of in situ bioremediation of soil contaminated by hydrocarbons, anodes arranged with two different ways (horizontal or vertical) were compared in microbial fuel cells (MFCs). Charge outputs as high as 833 and 762C were achieved in reactors with anodes horizontally arranged (HA) and vertically arranged (VA). Up to 12.5 % of the total petroleum hydrocarbon (TPH) was removed in HA after 135 days, which was 50.6 % higher than that in VA (8.3 %) and 95.3 % higher than that in the disconnected control (6.4 %). Hydrocarbon fingerprint analysis showed that the degradation rates of both alkanes and polycyclic aromatic hydrocarbons (PAHs) in HA were higher than those in VA. Lower mass transport resistance in the HA than that of the VA seems to result in more power and more TPH degradation. Soil pH was increased from 8.26 to 9.12 in HA and from 8.26 to 8.64 in VA, whereas the conductivity was decreased from 1.99 to 1.54 mS/cm in HA and from 1.99 to 1.46 mS/cm in VA accompanied with the removal of TPH. Considering both enhanced biodegradation of hydrocarbon and generation of charge in HA, the MFC with anodes horizontally arranged is a promising configuration for future applications.

A Pilot-scale Benthic Microbial Electrochemical System (BMES) for Enhanced Organic Removal in Sediment Restoration

“…2). It is probably because low molecular weight PAHs, containing two-to three-ringed PAHs were less toxic to microbes in the soil and can serve as a carbon source involved in the microbial metabolisms and accumulated more in the sediment8. Also high molecular weight PAHs, containing four-to six-ringed PAHs were hard to be decomposed by microbes.…”

“…Previous studies also suggested that Microbial Fuel Cells (MFCs) may be used for enhancing biodegradation of contaminants in anoxic environments by providing an inexhaustible source of terminal electron acceptors to a polluted environment89. Based on microbe–electrode interactions, various systems are being developed with time to not only remove organics, but also for the production and recovery of value-added products from substrates10.…”

“…On the other hand, Zhang et al . arranged anodes with two different ways for enhancing the bioremediation of contaminated soil, up to 12.5% of the total petroleum hydrocarbon (TPH) was removed in reactors with anodes horizontally arranged after 135 days, which was 95.3% higher than that in the disconnected control (6.4%)8. Yang et al .…”

“…Yang et al . built a 100 L sediment microbial fuel cells (SMFC) inoculate with heavily contaminated sediments, and the total organic chemical degradation efficiency was 22.1% in the electricity generating SMFCs, which is significantly higher than that in the open-circuited SMFC (3.8%) after two years’ long-term applicability without external electron donor addition8. It is worth noticing that in the past few years, considerable progresses have been made in MFC research, but significant challenges still remaining in river sediments restoration1012.…”

Sand amendment enhances bioelectrochemical remediation of petroleum hydrocarbon contaminated soil

“…The removal of hydrocarbons in soil is correlated with bio-current generated by exoelectrogenes (Li et al, 2014b;Lu et al, 2014a;Zhang et al, 2014). Using MFCs to remediate sediment contaminated by hydrocarbons, the degradation rate increased by up to 12 times from 2% to 24% in 66 d. However, according to the low power density reported previously (an average of 37 mW m À3 ), the system heavily suffered from very high internal resistance of $4 kX, mainly attributed to the high Ohmic resistance as a result of low conductivity in soil (Morris and Jin, 2012).…”