| A wetland treatment system, composed of two biofilters followed by two free water surface wetlands, was designed to enhance simultaneous nitritation, anammox and denitrification. It was operated to evaluate effects of pH and temperature on nitrogen removal from dairy wastewater. Furnace slag was utilized to increase pH. Nitritation and anammox bacteria accounted for about 70% of the bacteria in each unit. Temperature was the primary factor affecting nitrogen removal. Significant pH effects were identified when temperature was below 18 ºC. Ammonium removal rates were 1.10 and 0.86 g N/m2/d in the biofilters with pH at 8.2 and 7.7, respectively. At raised pH values (8.2-8.5) and temperatures (28.7 ºC on average), a biofilter removed 2.49 g N/m2/d of ammonium. The free water surface wetlands removed ammonium at 3.10 g N/m2/d when temperature was between 26.0 ºC and 13.8 ºC, and 1.24 g N/m2/d at temperature between 19.1 ºC and 15.1 ºC. |
