Purpose: Comparative study of various agar-agar (C14H24O9) percentage and different salts
concentration in the salt bridge is carried out to check the efficiency of microbial fuel cell.
Design/methodology/approach: Dual chambered microbial fuel cell was used for the
overall experiments. Anode and cathode chambers were made of 500 ml plastic jar. Salt bridge
was fabricated with agar-agar technical and 3 M NaCl in a PVC pipe of 2 cm long. Chemical
Oxygen Demand, pH and electrical conductivity of wastewater were examined. Oxygen was
supplied in the cathode chamber using the aquarium pump. Voltage (open circuit voltage) was
observed using digital multimeter. Graphite rods were used as anode and cathode electrodes.
Findings: Salt bridge was constructed of 3 M NaCl with 5, 7.5, 10 and 12 percent variation
of agar amounts in MFC. The maximum outputs were observed 301, 306, 325 and 337.25 mV
with the variation of agar 5, 7.5, 10 and 12 percentages respectively as well as chemical oxygen
demand (COD) removal efficiency was observed 47.92, 56.25, 52.08 and 64.58 percentages
respectively. The optimum agar concentration was found to be 12 percent and a maximum
voltage of 337.25 mV and COD removal of 64.58 percent was achieved. After the optimization
of agar percentage two salts i.e., Sodium chloride and potassium chloride were analysed. This
study also reveals that the NaCl salt bridge is more efficient than KCl salt bridge for the same
agar concentration. The maximum voltage for NaCl and KCl were 319 and 312 mV respectively.
Research limitations/implications: The amount of electricity production is low and field
scale implementation is difficult using microbial fuel cell. The research is still on progress in
this field.
Originality/value: here is very little research with salt bridge and MFC. Comparative study
of different mole of salt is available but agar variation is not yet studied.