Transformation of Inorganic Nitrogen in Slag-wetland During the Start-up Period
钢渣构造人工湿地运行初期无机氮转化特点研究

Lab-scale subsurface flow slag-wetlands were constructed to study the removal efficiency and transformation processes of low-concentration inorganic N during the start-up period. As for ammonium-dominated wastewater,the removal rates of total nitrogen (TN),ammonium nitrogen (NH+4-N),nitrate nitrogen (NO-3-N) and nitrite nitrogen (NO-2-N) were 0.12 g·(m2·d)-1,0.07 g·(m2·d)-1,0.10 g·(m2·d)-1 and 0.04 g·(m2·d)-1,respectively. Nitrifying bacteria was not detected by fluorescence in situ hybridization (FISH) on the slag. NH3 volatilization is the main contribution for N removal resulting from high pH (>10) and surface soil absorbed most of NH3. For nitrate-dominated wastewater,the removal rates of TN and NO-3-N were 0.23 g·(m2·d)-1 and 0.48 g·(m2·d)-1,and NO-2-N accumulated by 0.22 g·(m2·d)-1 during the process of denitrification. Removal efficiency of inorganic N for nitrate-dominated wastewater was higher than that for ammonium-dominated wastewater during the start-up period of slag-wetlands,so steel slag can be used as a substrate in constructed wetlands for extensive treatment of nitrate pollution.