Effect of methylene blue addition as a redox mediator on performance of microbial fuel cell using mud sediment of river ala

Abstract

Microbial fuel cells (MFCs) are also bioreactors that convert chemical energy stored in the bonds of organic matters into electricity through biocatalysis of microorganisms. Mud sediment of various depths (surface water, mud surface, 50cm, 100cm and 150cm) of River Ala were used in a double chamber microbial fuel cell (MFC) to generate electric current and comparative studies of the methylene blue mediator and mediator-less chamber were carried out. Microbial analyses, physiochemical analysis of the sediment were analyzed using standard methods. River Ala surface has the highest bacteria count of 2.4 x 10-5 and AL100cm has the lowest of 0.48 x 10-5 while AL100cm had the lowest fungi count of 0.2 x 10-6. The pH of sediment ranged from 7.52 to 6.52 and organic matter content 3.67 to 1.83(%). The mud surface has the highest conductivity and salinity content of 740 (µS) and 359 (ppm) respectively. The current and voltage readings obtained from of the methylene blue mediator chamber were slightly higher than that of the mediator-less chamber. Current 0.5 (mA) at only depth 50cm was observed in mediator-less chamber while 0.4 (mA) were common occurrences at depth 50cm and depth 100cm at the methylene blue mediator chamber; voltage readings of 0.3(V) only occurred depth 50cm in the mediator-less chamber while 0.3 (V) were observed at both depth 50cm and 100cm at the methylene blue mediator chamber. The low current and voltage reading were as a result of the high resistance it’s generated and its low organic matter content. It is also a confirmation that the mediator used has an impact in the current and voltage generated in microbial fuel cell.