Energy production and sanitation improvement using microbial fuel cells

Abstract

This study builds on the previous work of urine utilisation and uses small-scale microbial fuel cells (MFCs), working both as individual units in cascade or collectively as a stack, to utilise artificial urine. Artificial urine was prepared at concentrations typically found in real human urine with peptone employed as a surrogate proteinacious component. MFCs were constructed from Nanocure® polymer using rapid prototype technology. The anode and cathode electrodes were made of 15 cm2 carbon veil, folded down to fit in the 1 mL chambers. Eight MFCs were inoculated using activated anaerobic sludge; after 17 days of fed batch mode they were switched to continuous flow, initially at 0.09 mL/h and subsequently at 0.43 mL/h, resulting in HRT of 12.69 minutes/MFC. MFCs showed stable performance following the maturing period and produced, under polarisation experiments, peak power levels of 117 μW, corresponding to 962.94 W/m3. Continuous flow experiments data showed higher power production, increasing with the concentration of the carbon/energy source within artificial urine. The work demonstrates that artificial urine of varying composition can be successfully utilised for the production of energy and concomitant cleanup of organic waste. Finally, in line with the practical implementation and robotics work in our group, the small-scale MFCs were configured into a stack and directly energised electronic devices.