Plant microbial fuel cells with Oryza rufipogon and Typha orientalis for remediation of cadmium contaminated soil

Abstract

Plant microbial fuel cell (PMFC) is an emerging biotechnological device that integrates plants and microorganisms to convert chemical energy into electrical energy. In this study, we focused on the performance of PMFCs to remediate Cd(II)-contaminated soil. The wetland plants, cattail ( Typha orientalis ), and wild rice ( Oryza rufipogon ) were utilized in PMFCs to compare the effects of different plants under closed and open-circuit during 150 days. The cattail PMFCs and wild rice PMFCs under 20 mg/kg Cd(II) achieved the maximum voltage at 137.12 mV ± 13.08 and 350.50 ± 74.89 mV, respectively. For the Cd remediation, the cattail PMFCs and wild rice PMFCs could achieve 30.2% and 22.8% of Cd removal in the soil, respectively, and wild rice PMFCs with 5% chestnut biochar showed the highest Cd removal in the soil (31.7 %). The application of PMFCs for Cd(II) remediation could lead to the removal of metals in contaminated soil via bioelectrochemical processes and plant uptake. The Cd uptake by both cattail and wild rice was mainly accumulated in roots, reaching concentrations of 67.29 mg/kg and 16.49 mg/kg, and bioconcentration factors of 5.02 and 1.17, respectively. Furthermore, we observed that PMFCs enhanced immobilization of Cd contamination and reduced bioavailability in soil. Additionally, the microbial community analysis showed Proteobacteria including genera Anaeromyxobacter , Geobacter , Phenylobacterium , and Azospirillum were dominant at the anode region. Overall, this study has demonstrated that PMFC systems can be a promising technology for the treatment of soil contamination with Cd(II). • This study evaluated the performance of PMFCs to remediate Cd(II)-contaminated soil. • The wild rice PMFCs under 20 mg/kg Cd(II) had the maximum voltage. • The wild rice PMFCs with 5% chestnut biochar showed the highest Cd removal (31.7 %). • The Cd uptake by both cattail and wild rice was mainly accumulated in roots. • PMFCs enhanced immobilization of Cd contamination and reduced bioavailability.