As previously described, an important point was the necessity
to evaluate the removal efficiency of D. polymorpha independently
from any other settling process, which would remove the metals
adsorbed on suspended solids. The
filtering action of D. polymorpha
was
first evaluated on the effluent outflowing secondary settling.
However, since this effluent had a very low COD (10 mg/L) and,
consequently, a low suspended solid concentration (on which a
relevant amount of MEs is normally adsorbed)