In
addition, at a 4-day hydraulic retention time (HRT), the presence of plants significantly enhanced both
ammonia oxidation and TP removal in both batch and continuous modes of operation as compared to
that for unplanted beds. An estimation of the quantitative role of aeration from drain and fill operation at
a 4-day HRT, as compared to rhizosphere aeration by the higher aquatic plant, indicated that drain and
fill operation might account for only less than half of the higher aquatic plant’s quantitative contribution
of oxygen (1.55 g O2 per m2 per day for batch flow versus 1.13 g O2 per m2 per day for continuous flow).