Thus, cathode was located at 53 cm and the root system of
cattail was placed right above cathode. The root system at cathode
compartment may improve the oxygen concentration and consequently
enhance the cell reaction.
The distance between cathode to anode 1 (A1), anode 2 (A2) and
anode 3 (A3) were 15 cm, 30 cm, 45 cm,respectively. Both
electrodes were connected with stainless steel and insulated
copper wires across a 1000 O resistor. Each anode was connected
to cathode individually to measure the voltage of the system. The
voltage output was recorded during the study by using a data logger
(Midi LOGGER GL820 GRAPHTEC).
The current (I) and voltage (V) can be measured using digital
multimeter. Power (P = IV) can be obtained from calculation.
Power density could be calculated by dividing the power and current
with surface area (m2) of anode. Coulombic efficiency (CE) can
be calculated by using the formula below: