At the very beginning of operation (first 15 days) the presence and concentration of dissolved oxygen (SO) was the main factor affecting bacterial dynamics within the wetland. Fig. 3 represents SO concentrations within the wetland at days 3, 10 and 15, while in Fig. 4, the value of the highlighted term in Eq. (2) is represented in the same days. Eq. (2) describes the growth rate of fermenting bacteria (XFB) (mgCOD L− 1d− 1) and the highlighted term describes the inhibiting effect of dissolved oxygen (SO) on such rate. Note that for the sake of brevity the inhibition of oxygen is only shown for XFB, since its effects on the other anaerobic bacteria groups are almost identical.