Impact of sediment microbial fuel cells on the distribution of different forms of phosphorus in lake sediment and water

The continuous release of phosphorus from sediments by geochemical processes can cause endogenous eutrophication. This study examined the effect of carbon felt-sediment microbial fuel cells (CF-SMFCs) on the release of deposited phosphorus into the overlying water. In the CF-MFC system, the voltage ranged from 27 to 584 mV and the anode electrode potential increased from -130 mV to 202 mV. The Standard Measurements and Testing (SMT) method was employed to sequentially extract the sediment phosphorus in the sediments. A notable vertical increase in NaOH-P and HCl-P concentrations was observed downward in the sediment. The DGT phosphorus, visualized by Zr-Oxide DGT with submillimeter resolution, was removed by 52.04% in CF-SMFC. CF-SMFC notably facilitated the stabilization of phosphorus, promoting its conversion from pore water to sediment. The underlying mechanism suggests that the dissolution of solid-phase phosphorus into the overlying water was mitigated by the competition for organic substrates between Fe(III) reduction and the solid electrode. CF-SMFC can be used to increase the redox potential of the sediment and in-situ stabilize phosphorus in the sediment.