Nitrogen Removal in a Partially Saturated Vertical Subsurface Flow Constructed Wetland Used for Restaurant Wastewater Treatment

The objective of this research was to evaluate the nitrogen removal efficiency of a partially saturated vertical subsurface flow constructed wetland (VSFCW) used on university restaurant (UR) effluent treatment. The research was conducted in southern Brazil ($\text{latitude}:-23.304218$; $\text{longitude}:-51.172223$) on constructed wetland with $1{\mathrm{m}}^2$ of surface area, and the saturation layer was 0.25 m upper bottom. The results of this monitoring research extended for 6 months in a cultivated Heliconia rostrata system. The average applied loads were $37.6\mathrm{g}/{\mathrm{m}}^2$ of chemical oxygen demand (COD), $4.10\mathrm{g}/{\mathrm{m}}^2$ of total Kjeldahl nitrogen (TKN), $1.74\mathrm{g}/{\mathrm{m}}^2$ of ammoniacal nitrogen ($\mathrm{N}\text{-}{\mathrm{NH}}_4^{+}$), and $4.28\mathrm{g}/{\mathrm{m}}^2$ of total nitrogen (TN). The mean efficiencies of removal/conversion were 95.34% for COD, 96.95% for TKN, 93.99% for $\mathrm{N}\text{-}{\mathrm{NH}}_4^{+}$, and 69.39% for TN. The removed loads were $35.9\mathrm{g}/{\mathrm{m}}^2$ of COD, $3.98\mathrm{g}/{\mathrm{m}}^2$ of TKN, $1.68\mathrm{g}/{\mathrm{m}}^2$ of $\mathrm{N}\text{-}{\mathrm{NH}}_4^{+}$, and $3.02\mathrm{g}/{\mathrm{m}}^2$ of TN. The results showed system operational stability and the high efficiency on organic matter and TN removal of this effluent type.