ZHANG Yan, FU Chunyan, YAN Baixing, et al. Effect of Ferrous Iron Addition on the Layering Effect of Contaminant Removal in Horizontal Subsurface Flow Constructed Wetlands[J]. 2019, 33(1): 306-314.
DOI:
ZHANG Yan, FU Chunyan, YAN Baixing, et al. Effect of Ferrous Iron Addition on the Layering Effect of Contaminant Removal in Horizontal Subsurface Flow Constructed Wetlands[J]. 2019, 33(1): 306-314. DOI: 10.13870/j.cnki.stbcxb.2019.01.048.
Effect of Ferrous Iron Addition on the Layering Effect of Contaminant Removal in Horizontal Subsurface Flow Constructed Wetlands
For understanding the effect of ferrous iron addition on contaminant removal in different layers of horizontal subsurface flow constructed wetlands
the nitrogen and COD removal and their mechanisms were investigated in this study. The results showed that addition of ferrous iron was beneficial to the removal of total nitrogen
nitrate nitrogen and ammonium nitrogen
and the removal of nitrogen was optimized at the ferrous iron concentration of 50 mg/L. However
the excessive ferrous iron addition inhibited nitrogen removal
especially for the removal of ammonium nitrogen in the lower layers
while the nitrogen removal with ferrous iron addition was greater than that without ferrousiron. As well
ferrous iron addition altered the layering effect of the three inorganic forms of nitrogen. At the beginning of the experiment
ferrous iron addition improved the COD removal
affecting the COD removal in the different layers. Iron concentrations in the different layers dropped rapidly after the input of ferrous iron
while pH values in the effluent increased first and then kept in a stable trend due to the valence structure and hydrolytic characteristics of iron. The pH value in the lower layer was lower than those in the upper and middle layers. Iron properties also caused the changes of oxidation reduction potential (ORP) in different layers. Addition of ferrous iron promoted the layering effect of ORP
but slowed down the decrease of ORP.
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