Browsing by Author "Tapia, Natalia"

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    Energy and copper recovery from acid mine drainage by microbial fuel cells. Effect of the hydrochar doping on carbon felt anodes
    (2025) Delgado, Yelitza; Tapia, Natalia; Lopez, Ester; Llanos, Javier; Vargas, Ignacio; Fernandez-Morales, Francisco Jesus
    This work investigates the performance of a Microbial Fuel Cell (MFC) for Acid Mine Drainage (AMD) treatment using bare and hydrochar-doped carbon felt (CF) anodes. Hydrochar was synthesized through hydrothermal carbonization of Spergularia rubra, followed by activation at 500 degrees C, resulting in improved O/C and H/C ratios of 0.26 and 0.78, respectively. The study reveals that doping CF anodes with non-activated and activated hydrochar significantly enhances copper recovery and electricity generation. The highest copper recovery rate of 16.0 mg/L h- 1 was achieved with activated hydrochar-doped CF (CFaH) anodes, followed by 10.6 mg/L h- 1 with nonactivated hydrochar-doped CF (CFnaH) anodes, and 7.1 mg/L h- 1 with bare CF anodes. Hydrochar doping also improved the maximum current density to 0.21 mA cm- 2 compared to 0.16 mA cm- 2 with bare CF anodes. These results demonstrate the potential of hydrochar-doped CF anodes for efficient metal and energy recovery from AMD, offering a sustainable and energy-efficient alternative to conventional methods.
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    Long-term evaluation of soil-based bioelectrochemical green roof systems for greywater treatment
    (2024) Tapia, Natalia; Gallardo-Bustos, Carlos; Rojas, Claudia; Vargas, Ignacio T.
    Water scarcity has generated the need to identify new sources. Due to its low organic contaminant load, greywater reuse has emerged as a potential alternative. Moreover, the search for decentralized treatment systems in urban areas has prompted research on using green roofs for greywater treatment. However, the performance of organic matter removal is limited by the type of substrate and height of the growing media. Bioelectrochemical systems (BESs) improve treatment performance by providing an additional electron acceptor (the electrode). In this study, nine reactors under three different conditions, i.e., open circuit (OC), microbial fuel cell (MFC), and microbial electrolysis cell (MEC), were built to evaluate the treatment of synthetic greywater in a substrategrowing medium composed of perlite and coconut fiber and operated in batch-cycle mode for 397 days. The results suggested that using BESs enables greywater treatment and the removal of pollutants to levels that allow their reuse for irrigation. Furthermore, electrical conductivity was reduced from 732.4 +/- 41.2 mu S/cm2 in OC to 637.32 +/- 22.73 mu S/cm2 and 543.15 +/- 19.69 mu S/cm2 in MEC and MFC, respectively. The soluble chemical oxygen demand in the latter treatments reached 76% removal, compared to levels above the OC, which only reached approximately 67%. Microbial community analysis revealed differences, mainly in the cathodes, showing a higher development of Flavobacterium, Azospirillum, and Zoogloea in MFCs, which could explain the higher levels of organic matter removal in the other conditions, suggesting that the BES could produce an enrichment of beneficial bacterial groups for treatment. Therefore, implementing BESs in green roofs enables sustainable longterm greywater treatment.