Carbon source and influent COD/N (chemical oxygen demand: total nitrogen) pose distinct effects on nitrogen removal efficiency and microbial community structure of constructed wetlands. To investigate the interactive effect of… Click to show full abstract
Carbon source and influent COD/N (chemical oxygen demand: total nitrogen) pose distinct effects on nitrogen removal efficiency and microbial community structure of constructed wetlands. To investigate the interactive effect of carbon source with COD/N on nitrogen removal and microbial community structure in subsurface flow constructed wetlands, glucose (C6H12O6) and sodium acetate (C2H3NaO2) were used to determine five COD/N ratios in nine groups of constructed wetlands divided into glucose constructed wetlands and sodium acetate constructed wetlands. Results showed that efficiency in COD removal increased with COD/N, and peak value reached 92.7%. Interactive effect of carbon source with COD/N on system pH and ammonium removal was notably significant. Differences in ammonium removal performance between treatments were achieved by the variation of influent COD/N ratio and the change of system pH resulted from different carbon sources, and the result suggested that glucose was a better choice at high COD/N ratio. System microbial community structure was significantly affected by carbon source, influent COD/N ratio and their interaction. Microbial biomass in constructed wetlands significantly increased with increasing COD/N ratio. Higher density and diversity of fungus were observed in glucose constructed wetlands, particularly at COD/N ratio of 7 and 10.
               
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