Abstract-Sediment microbial fuel cell (SMFC), an electrochemistry technology, is expected to be an alternative method for improving both water and sediment environments. This study presents the development of a solar cell-combined SMFC system (SC-SMFC), and the improvement of sediment and water environments by SC-SMFC through laboratory experiments. The distributions of pH and redox potential (ORP) in sediment were formed, in which larger decreases in pH and increases in ORP were found near the anode after the SC-SMFC application. From the pH and ORP distributions, the sediment located between 0 mm and 150 mm from the anode was strongly influenced by the SC-SMFC application, which was around 2-fold higher than that influenced by the application of SMFC alone. Interestingly, the system application caused the dissociation of calcium and iron complexes. This dissociation increased the concentrations of calcium and ferric ions, leading to the fixation of phosphate in the sediment. Furthermore, different decomposition characteristics of organic matter were found in the sediments near and far from the anode. In addition, the quality of overlying water was also improved by the system application. For example, the dissolved oxygen concentration remained higher near the sediment surface. These findings validate the usefulness of SC-SMFC as an alternative method for improving both sediment and water environments concurrently.

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Abstract-Metal ion or clay mineral-adsorbed organic matter present in littoral sediment is known as hardly decomposed organic matter, which is difficult to use as a natural resource. This study is aimed at changing the organic matter characteristics of littoral sediment through the application of solar cell-combined sediment microbial fuel cell (SC-SMFC). The experimental results showed that the sediment pH decreases and the concentration of metal ions in the sediment pore water increases after the application of SC-SMFC. This suggests the dissociation of metal complexes in the sediment. From the analysis results of organic matter characteristics, variations in the ignition characteristics of the sediment and the absorbance at wave number ranges of 3300-3800 and 800-1800 cm -1 were confirmed, indicating changes in organic matter characteristics of the sediment. It can be concluded that SC-SMFC can separate organic matter from metal complexes, leading to the transformation of organic matter in sediment from valueless into a useful product.