Overall, it was apparent that total nitrogen (TN) concentration
of the outlet water was not significantly different between the two
conditions during any treatment (Fig. 2) and any increase in TKN
removal were accompanied by a decrease in nitrate/nitrite removal.
Total nitrogen removal was significant (Wilcoxon, p < 0.01) in all
treatments except treatment 2 (Fig. 2). The largest difference in
median TN removal between submerged and flood drain biofilters
removal was in treatment 1 (31% removal in submerged biofilters
and 45% removal in flood drain.