Operation of SSF constructed wetland in batch mode (alternating
drain and fill cycles) is a strategy that may improve both nitrogen
and phosphorus removal efficiency in wastewater wetlands
(Burgoon et al., 1995; Stein et al., 2003). Wijler and Delwiche (1954)
first proposed the idea that alternating periods of submergence and
drying of soils might enhance nitrogen (N) loss compared to
a continuously flooded condition. They reasoned that alternating
periods of aerobic and anaerobic soil conditions could facilitate the
sequential coupling of nitrification and denitrification, with nitrate
generated during the aerobic phase being denitrified in the anaerobic
phase. The long-term mechanism of phosphorus (P) retention
in wetlands is the adsorption of orthophosphate onto the surfaces of
soil minerals, particularly hydrous oxides of iron and aluminium
(Richardson and Nichols, 1985; Chambers and Odum, 1990)