where, M = 32, the molecular weight of oxygen, I = current,
F = 96,485 C mol−1 of electrons, Faraday’s constant, b = 4 is the number
of electrons exchanged per mole of oxygen, V is the total volume
of the reactor, and COD is the change in COD of water and sediment
over time t.
The results of experimental runs of the 23 factorial design were
expressed in terms of a polynomial regression model as: