Pollutant removal and bioelectricity generation from urban river sediment using a macrophyte cathode sediment microbial fuel cell (mSMFC)

Abstract

Sediment microbial fuel cell (SMFC) efficacy depends highly on organic matter flux and dissolved oxygen (DO) at the anode and cathode, respectively. However, utilizing floating-macrophyte for elevated DO supply at the cathode has not been fully explored. Therefore, a novel floating-macrophyte implanted biocathode single-chamber SMFC (mSMFC) was developed for the simultaneous removal of pollutant and bioelectricity generation from polluted urban river sediment. With Lemna minor L. employed in mSMFC, high pollutant removal was feasible as opposed to the control bioreactor. Total COD, nitrate and sulfate removal reached 57%, 99%, and 99%, respectively. Maximum voltage output, power density, columbic efficiency, normalized energy recovery, and net energy production observed was 0.56 ± 0.26 V, 86.06 mW m−3, 24.7%, 0.033 kWh m−3 and 0.020 kWh m−3, respectively. Alternatively, when floating-macrophyte (predominantly Pistia stratiotes) was employed in the catholyte, DO increased significantly to about 10 mg L−1 in the mSMFC. 16S rRNA gene sequencing revealed Euryarchaeota-(90.91%) and Proteobacteria-(59.68%) as the dominant phyla affiliated to archaea and bacteria, respectively. Pollutant removal mechanisms observed within the mSMFC included bioelectrochemical oxidation at the anode and reduction reaction and macrophyte hyperaccumulation at the cathode. The novel mSMFC system provided an effective approach for the removal of pollutant and bioelectricity generation.