Fig. 4. The Nyquist and Tafel spectra. (A) Illustrates the spectra of the abiotic system, (B) illustrates the spectra of the biotic system for 7^th, 14^th, 21^st and 28^th days, (C) shows the combined spectra for both abiotic and biotic systems, and (D) elucidates the Tafel plots of the abiotic and biotic systems (on the 28^th day).