REDOX DISTRIBUTION PROFILES OF FLOODED PADDY SOILS WITH MICROBIAL FUEL CELL APPLICATIONS

Abstract

Microbial fuel cell is one of our considerations to control denitrification redox reactions inflooded rice soils. An independent study was conducted after a nitrogen behavior study in flooded rice soilsaccounted for microbial fuel cell systems and microbial fuel cell systems with an externally applied voltage.External voltage was applied in the aim of increasing microbial fuel cell efficiencies, for the better control ofsoil redox potential. But, their redox controlling potentials and denitrification controlling were lower than thatof microbial fuel cell systems. It is hypothesized, that the lower controlling potentials were due to the redoxdistributions effected with the distance to the anode of the circuit where the external voltage was connectedthrough. Therefore, soil redox distributions at three depth profiles were compared in both systems and controlsover the period of flooding. In external voltage applied systems, the redox potential of the soil away from anodewas not much effectively controlled as of microbial fuel cell systems, although the middle soil portions nearanode area were of higher redox potentials. At depths of 10 and 20 cm away from the soil surface, the redoxpotential increased more with MFCs and moderately with MFC-extV, but reduced with non-MFCs over theperiod. Accordingly, most electrons from whole soils were not freely transferred to the anode, except that fromnear anode areas where the external voltage was connected through. Microbial fuel cell systems with externallyapplied voltage had a lower impact on controlling denitrification than that of microbial fuel cell systems alone.