Nitrate was removed in both conditions during treatment 3
(Wilcoxon p = 0.01 submerged, p < 0.01 flood/drain), but in treatment
2 and 4 no significant differences between inlet and outlet
concentrations were observed. In treatments 2 and 3, outlet nitrate
concentration was significantly lower in the submerged biofilters
than in the flood/drain biofilters (Mann–Whitney U, p < 0.01).