A laboratory-scale, intermittently fed, organicbased
vertical flow filter was tested as a pre-treatment of
high-strength urban wastewater to reduce the risk of
clogging in treatment wetlands. At an average hydraulic
loading rate of 815 L/m
2 day and average surface loading
rates of biological oxygen demand of 458 g/m
2 day,
chemical oxygen demand of 594 g/m
2 day and suspended
solids of 310 g/m
2 day, the organic-based vertical flow
filter achieved removal efficiencies of 48 % of biological
oxygen demand, 45 % of chemical oxygen demand, 69 %
of suspended solids and 51 % of turbidity. For this unit,
removals were significantly correlated with organic surface
loading rates but not with hydraulic loading rate. Additionally,
the organic-based vertical flow filter removed
almost completely the hormone residues studied: estrone,
17β-estradiol, 17β-ethynyl estradiol, diethylstilbestrol,
estriol, norethisterone and testosterone, most probably by
the combination of adsorption onto the organic substrate
and biodegradation. The efficiency of the combined system
was remarkable for biological oxygen demand (97 %),
chemical oxygen demand (89 %), suspended solids and
turbidity (99 %), fecal coliforms and
E. coli
(99.9 %) and
fecal enterococci (99 %).
