旭硝子財団助成研究成果報告2023

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98Dao Suwansang JANJAROEN99Jitti KASEMCHAINAN100Jenyuk LOHWACHARINMetal recovery from municipal solid waste fly ash using sulfur-oxidizing bacteria(Project 2021)Primary Battery Recycling towards Circular Economy and Environmental Sustainability(Project 2021)Optimized operation of slow and rapid sand filters based on relationships between microbial community structure and DOM geochemistry and biodegradability for small-to-medium scale waterworks(Project 2021)旭硝子財団　助成研究成果報告（2023）74This study aims to reuse food waste (FW) as growth media for bacterial cultures for heavy metal remediation purposes. The best natural medium was selected on the basis of the carbon, nitrogen, and other sources from different FW. The optimized parameters of the media were assessed with reference to laboratory media for microbial culture cultivation. The batch culture of Comamonas terrae showed growth stability for around 16 days in the pig bone medium. C. terrae showed the best growth at a pH of 7.4, a temperature of 35°C, and a medium concentration of 10 g/L. The isolated strain showed multi-metal removal efficiencies of 52% (Cd), 63% (Cr), 62% (Pb), and 55% (Zn). The Fourier transform infrared spectroscopy results revealed diverse functional groups on the initial and final days of adsorption of C. terrae. In addition, physicochemical characterizations also showed that C. terrae was very effective for heavy metal remediation. Therefore, pig bone waste is a cost-effective medium and a good solution for the valorization and reuse of FW in line with the current circular economy paradigm.Recycling Mn compounds from spent alkaline batteries (SAB) not only follows the ongoing trend of circular economy, but also conserves the nature with less disposal of the battery wastes. Both pyrometallugical and hydrometallurgical techniques were included to aim for low-cost, environmental-contaminant-minimized, and mass-production process. The SAB-electrode-powder mainly consisted of Mn-(III)-compounds by XRD, together with ca. 6 wt% carbon by XRF. Heat-treatment under N2-gas was executed on the powder at a temperature from 650 to 950 °C for 2 h. At 950 °C, XRD revealed only crystalline MnO; yet other components were amorphous/nanocrystalline C- and Zn based substances from XRF. Leaching the heated SAB-powder was tried with stoichiometric volume, + 20 vol%, or + 50 vol% excess of 2-M-H2SO4 to receive MnSO4-solution – the best leaching efficiency of 98 %. The leachate was well-mixed with the stoichiometric KMnO4 mass at 30, 60, or 90 °C for 1 h, giving the 99 % yield SAB-MnO2. The SAB-MnO2 was electrochemically tested (rate and long-cycling tests) as Zn-ion batteries (ZIBs). Both tests show promising results: especially for the long cycling at 5 mA/g, good capacity retention of the ZIBs using the SAB-MnO2 was recognized when the ZIBs with the commercial MnO2 was a reference.Biological activity in rapid sand filters is drawing attention especially when no pre-chlorination or small dose is applied while slow sand filters are facing difficulty to meet drinking water guidelines for disinfection by-products. This research anticipated that geochemistry of dissolved organic matter (DOM) influences the microbial community structure of rapid sand filters. Therefore, the prokaryotic community structure was evaluated using 16S rRNA gene-based 454 pyrosequencing. DOM was characterized by total organic carbon