Self-sustainable nutrient recovery associated to power generation from livestock's urine using plant-based bio-batteries

Plant-based bio-batteries, i.e., plant microbial fuel cells (P-MFCs) are devices that convert chemical energy into electrical energy by using microbial activity (as catalysts). These sustainable technologies have previously been used in different fields of investigation such as wastewater treatment, bioremediation of pollutants, heavy metals and energy recovery, and low-cost and eco-friendly nutrient recovery. In this study, a P-MFC embedded with Stevia rebaudiana was built with a clay cup for the direct reutilization of nutrients associated with the generation of bioelectricity. The P-MFCs were inoculated with 642.865 mL (congruent to 643 mL) of livestock's urine from three species of domestic animals such as cow, goat, and sheep urine. Higher direct reutilization of NH4+-N (94%), PO43 (98%), and K (33%) was achieved in P-MFC inoculated with cow urine. The maximum power density and maximum current density increased by 98% in the P-MFC inoculated with sheep urine under a polarization study. For the long-term operation (43 days), maximum power density of 46.97 +/- 0.67 mW m(-2) (at maximum current density of 77.45 +/- 0.24 mA m(-2)) was found in P-MFC-3 (inoculated with goat urine) with an external resistance of 1000 Omega. The development of a P-MFC system with self-sustainable auto-feed through the livestock's urine waste in clay cup is reported, to our knowledge for the first time, and is revealed as a viable and economical alternative for the generation of sustainable and renewable energy.