Decreasing sulfide in sediment and promoting plant growth by plant-sediment microbial fuel cells with emerged plants

Four plant-sediment microbial fuel cells (plant-SMFCs) with four plant species, Oryza sativa, Acorus calamus, Spathiphyllum petite and Chamaedorea elegans, were built to investigate sulfide concentrations, pH and oxidation-reduction potential (ORP) in the sediment as well as plant growth. Sulfide concentrations at 1 and 2cm depth of sediment in plant-SMFCs and their control reactors were 1.66 +/- 0.30, 9.29 +/- 3.46, 2.38 +/- 0.10 and 24.20 +/- 1.02molg(-1), respectively. The ORP in water and sediment of 1 and 2cm depth in plant-SMFCs was 106.0 +/- 7.7, -142 +/- 30 and -209 +/- 9mV, respectively. The ORP in the three control reactors was 119.0 +/- 11.5, -209 +/- 9 and -386 +/- 2mV, respectively. Harvest of O. sativa, A. calamus, Spathiphyllum petite and C. elegans was 0.218 +/- 0.009, 0.136 +/- 0.007, 0.127 +/- 0.007 and 0.340 +/- 0.007gDWg(-1)GW in the plant-SMFCs, while that of their control reactors was 0.179 +/- 0.011, 0.127 +/- 0.008, 0.102 +/- 0.007 and 0.318 +/- 0.006gDWg(-1)GW, respectively. The results showed that sulfide concentrations decreased in sediments of plant-SMFCs, while the ORPs in both the overlying water and sediments increased. Moreover, plant growth due to operating plant-SMFCs was promoted. Running plant-SMFCs abates the toxicity of sulfide to the emerged plants as well as decreases the sulfide emission in water-plant-sediment systems.