Iron-Added Sediment Microbial Fuel Cells to Suppress Phosphorus Release from Sediment in an Agricultural Drainage

Abstract

Phosphorus (P) release from sediment caused eutrophication in Kojima Lake, Japan. The efficiency of iron-added sediment microbial fuel cells (SMFCs) in regulating P release from agricultural drainage sediment was investigated in this study. Surface sediment collected from an agricultural drainage canal flowing into Kojima Lake was mixed with iron oxide (Fe 2 O 3 ) or amorphous iron oxyhydroxide (FeOOH) at 50 mmol kg −1 . A 14.6-cm high acrylic pipe was filled with 80 mL of deionized water after 130 g of sediment was placed. A 3 × 3 cm graphite felt was used for the anode in a dual chamber SMFC, while a carbon rod was used for the cathode. Three treatments: No Fe, Fe 2 O 3 , and FeOOH, were operated for 408 h under open or closed circuit conditions. Results showed that FeOOH addition lowered P release from sediment regardless of SMFC operational conditions, suggesting that higher P adsorption by FeOOH may mask the effect of SMFCs. Fe 2 O 3 did not reduce total P concentration in the overlying water. In addition, electricity generation was not enhanced by Fe-added SMFCs. Although SMFCs increased sedimentary redox potential, P release was not suppressed by the SMFC operation, indicating that organic P would be released by SMFCs from P-rich sediment.

Phosphorus Release from Agricultural Drainage Sediments with Iron-Added Sediment Microbial Fuel Cells

“…Under CC conditions, NH 4 + -N release from sediment was higher than under OC conditions. These results were consistent with Perera et al [39] and Xu et al [54]. In LS-OC treatment, NH 4 + -N reduced significantly at the end due to N immobilization.…”

“…Accordingly, we set up the hypothesis that Fe 3+ addition to SMFCs may reduce total phosphorus (TP) release from sediment while producing high electricity. Under short-term SMFC operation for 17 days, we found that high P adsorption by Fe 3+ oxyhydroxides reduced P release from Kojima Lake sediment with high TP content (4.7 g kg −1 ) regardless of SMFC operation until day 15 and then Fe 3+ addition increased P release into the overlying water [39]. Therefore, additional studies on long-term SMFC operations for Fe-added sediment are required.…”

“…A dual-chamber SMFC was designed to prevent oxygen diffusion into the anode [40]. The SMFC design was illustrated in Perera et al [39]. The anode chamber was made of a 14.6 cm-high acrylic tube with a 4.5 cm internal diameter.…”

“…3--P and ammonium (NH 4 + -N) were measured using a continuous flow analyzer (2-HR, QuAAtro, AutoAnalyzer, Bltec, Tokyo, Japan) after filtration (0.2 µm). Moles of electrons transferred via external circuits under CC conditions, decomposed carbon, and mineralized N and P were calculated according to Perera et al [39]. The below-mentioned anode-half reaction was considered to have occurred during organic matter decomposition (equation ( 1)).…”