Nitratfe removal in wetland microcosms

The effect of hydraulic loading rate (HLR; 5 to 20 cm day−1) and carbon addition (1-6 g dried plant material per week) was determined at two temperatures (28°C and 35°C) in 18 flow-through sediment-water wetland microcosms that were fed nitrate-contaminated water (30 mg N L−1). Nitrate removal efficiencies varied from 8% to >95%, decreasing with increasing HLRs and increasing with increasing carbon addition rates. The effect of HLR and carbon addition rate were integrated into the C:N ratio, which alone was highly predictive of nitrate removal efficiency. As nitrate removal efficiencies increased, dissolved organic carbon in the effluent also increased, as did chloroform formation potential. Nitrate-treatment wetlands may be a feasible method of remediating nitrate-contaminated groundwater.