Simultaneous phytoremediation of Cu2+ and bioelectricity generation in a plant-microbial fuel cell assembly growing Azolla pinnata and Lemna minor

Abstract

The relationship between power generation in a Plant-Microbial Fuel Cell (PMFC) and phytoremediation were observed in this paper. It is hypothesized that both power generation and metal uptake capacity will be enhanced synergistically upon the combination of the two processes. To test the hypothesis, the experiment was composed of three set-ups: (A) PMFC only, (B) phytoremediation only, and (C) PMFC combined with phytoremediation. A maximum power density for set-up A of 3.43 μW/m2 and 247.11 μW/m2 for Azolla pinnata and Lemna minor, respectively, while a maximum power density for set-up C of 17.82 μW/m2 and 1076.16 μW/m2 for the two plants were observed. The values showed a significant increase in power density for set-ups where copper ions are present (set-up C). The internal resistance of the PMFCs were also investigated. It was observed that internal resistance continuously decreased through time and the presence of copper ions in set-up C of both plants resulted to a lower internal resistance, equating to higher power densities. In terms of phytoremediation potential, the results showed that the presence of electrodes in the hybrid set-up induced the plants to absorb more copper ions than the control. The copper ion uptake increased by about 18% for A. pinnata and 38% for L. minor in phytoremediation tests in PMFCs. Overall, the combination of PMFC technology and the concept of phytoremediation has been shown to benefit both power generation and metal uptake capacity. The results of this study can be used to enhance the clean-up of metal contaminants while simultaneously providing power in-situ.