Wastewater was fed from the bottom (by a peristaltic pump
with flow rate 60 l h1) and uniformly distributed through
a diffuser. The distribution of dissolved oxygen and substrate to
biomass was assured by an external loop (flow rate 90 l h1), which
recycled the liquid phase from the bottom in a continuously upflow
operation. The opening of a motorized valve allowed the
discharge of the effluent from a port located in the liquid phase over
the bed. Head losses at the bottom of the bed were monitored in
order to wash the filter with compressed air when they became
greater than a pre-defined value.
Fig.