3.2.4. Efficiency of VFCW for the removal of bacterial indicators of
pollution
The geometric mean of the bacterial indicators counts namely;
total coliform (TC), fecal coliform (FC) and E. coli in the treated
effluent were 2.60 × 10
3
, 1.25 × 10
3
and 1.11 × 10
3
MPN/100 ml.
The average removal efficiency of all bacterial indicators varied
between 94% and 99.99%. The removal efficiency of coliform bacteria was in good agreement with Soto et al. (1998) and Vymazal
et al. (2000). The high removal rate may be explained by the high
oxygen concentration in the VFCW, as well as the high temperature (25–30
◦
C) that causes aerobic environment. Different research
works have demonstrated that anaerobic conditions prolong the
survival of coliforms in constructed wetlands and in contrast, aerobic conditions, such as those predominant in VFCW enhance the removal rate.