Remediation of riverbed sediments using plant microbial fuel cells

The electricity generation capacity of plant microbial fuel cell (PMFC) plays an important role in the remediation of river sediments. Different plant species can significantly affect the overall performance of PMFC systems, and appropriate plant selection is therefore essential for improving both electricity generation and sediment remediation efficiency. In this study, riverbed sediment was used as the anodic substrate, and four PMFC systems were constructed using Arundinella anomala, Acorus calamus, Oryza sativa, and Spartina anglica as coupled plants. A conventional microbial fuel cell (MFC) and a plant-only group with Acorus calamus, which showed the best growth condition in the river sediment, were used as control groups. The effects of plant species on the electricity generation performance and sediment remediation efficiency of PMFCs were evaluated by measuring output voltage, power density, apparent internal resistance, and the removal rates of organic matter, ammonia nitrogen, and total phosphorus. The results showed that the overall performance of the four groups of PMFC systems was superior to that of both MFC and plant-only system. The maximum output voltage and organic matter removal rate of MFC were 135.14 mV and 4.87%, respectively, while the organic matter removal rate of the plant-only system was 3.03%. The overall performance of the four PMFC systems ranked as follows: Acorus calamus-PMFC > Spartina anglica-PMFC > Oryza sativa-PMFC > Arundinella anomala-PMFC. Among them, the Acorus calamus-PMFC exhibited the best electricity generation performance, with a maximum output voltage of 512.50 mV, a power density of 11.7 mW/m2, and an apparent internal resistance of 123.69 Ω. The removal efficiencies of organic matter, ammonia nitrogen, and total phosphorus in the sediment reached 15.29%, 53.27%, and 12.17%, respectively. These results demonstrate that plant spieces significantly influence the overall performance of PMFC systems, and Acorus calamus is the most suitable plant for enhancing both electricity generation and sediment remediation. The research results can provide experience support and data reference for the study and application of riverbed sediment remediation.