钢渣构造人工湿地运行初期无机氮转化特点研究

以钢渣为主要基质构建小型潜流湿地，探索湿地运行初期对污水中低浓度无机氮的去除效果及氮转化特点.结果表明，钢渣湿地对氨氮型污水中总氮(TN)、氨氮(NH⁺₄-Ｎ)和硝氮(ＮＯ^-₃-Ｎ)的去除速率分别是0.12、 0.07和0.10 　g·(m²·d)^-1，亚硝氮(ＮＯ^-2-Ｎ)积累速率是0.04 　g·(m²·d)^-1；荧光原位杂交方法没有在钢渣基质上检测到硝化细菌，NH⁺₄-Ｎ去除的主要途径是在高pH (>10)的水环境下挥发到上层土壤，由土壤层去除；钢渣湿地对硝氮型污水中TN的去除速率是0.23 　g·(m²·d)^-1，ＮＯ^-₃-Ｎ的去除速率是0.48 　g·(m²·d)^-1，ＮＯ^-₃-Ｎ在钢渣湿地内主要通过反硝化去除，反硝化过程中出现ＮＯ^-2-Ｎ积累，积累速率为0.22 　g·(m²·d)^-1.钢渣湿地运行初期对硝氮型污水的处理能力高于氨氮型污水，钢渣可作为一种强化反硝化基质应用于ＮＯ^-₃-Ｎ的去除或其他组合工艺中.

Transformation of Inorganic Nitrogen in Slag-wetland During the Start-up Period

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.