负载型纳米零价铁(nZVI)强化垂直流人工湿地反硝化作用研究

Analysis of the enhancement of denitrification efficiency in vertical flow constructed wetlands by supported nanoscale zero valent iron(nZVI)

通过在垂直流人工湿地缺氧反硝化区添加负载型纳米零价铁(n ZVI),分析不同负载型n ZVI投加量对反硝化的影响,研究不同进水C/N条件下负载型nZVI参与反硝化的效果。结果表明:投加负载型nZVI 4 g的人工湿地装置对硝氮去除效果最佳,当C/N为6、HRT=1 d、进水NO_3^--N为50 mg·L^(-1)时,其NO_3^--N去除率比未添加负载型n ZVI的人工湿地装置提高15%;随负载型n ZVI投加量的增加,人工湿地装置出水pH值和NH_4^+-N、NO_2^--N的浓度增加;在进水C/N为0、2、4、6的人工湿地装置中,其对NO_3^--N的去除率随C/N升高而升高;统计分析表明,进水C/N与负载型n ZVI投加量对人工湿地反硝化都具有显著影响,且两者具有协同作用,碳源的存在可以促进负载型nZVI参与人工湿地反硝化。

In the treatment of low C/N sewage, the shortage of electron donors is a major factor inhibiting denitrification efficiency. Through the addition of supported nanoscale zero valent iron （nZVI） to the anoxic denitrification zone in vertical flow constructed wetlands （CWs）, we examined the influence of the dosage of supported nZVI on the denitrification efficiency for different C/N ratios in the influent. The re- suits showed that the addition of 4 g supported nZVI into CW experimental equipment was optimal; when the C/N of the influent was 6, the hydraulic retention time was 1 day, and the NO^-N concentration of the influent was 50 mg·L^-1. Additionally, the removal rate of NO^-N was 15% high when adding 4 g supported nZVI to the CW experimental equipment than that in a CW reactor without the addition of sup- ported nZVI. The pH and concentrations of NH4-N and NO2--N in the effluent of CWs showed an increasing trend following the addition of supported nZVI. The removal efficiency of NO3- -N increased as the C/N ratio increased from 0 to 6. There was a synergistic effect between C/ N and the dosage of supported nZVI; thus, the presence of carbon sources could promote the involvement of supported nZVI in denitrifica- tion in CWs.