The treatment system operation worked well over the
entire experiment duration. The produced sludge in the
bio-contact oxidation tank was small so that clogging never
occurred over the duration of the experiment. One reason
was that the tidal wastewater has high salinity, so that only
adapted microbes can grow and degrade the pollutants. The
other cause was that the oyster shell had a large porosity,
thus sludge obstruction could not easily occur.