Enhanced nitrogen removal in biochar-added surface flow constructed wetlands: dealing with seasonal variation in the north China

Li, Jing; Fan, Jinlin; Liu, Daoxing; Hu, Zhen; Zhang, Jian

Enhanced nitrogen removal in biochar-added surface flow constructed wetlands: dealing with seasonal variation in the north China

2019

Li, Jing | Fan, Jinlin | Liu, Daoxing | Hu, Zhen | Zhang, Jian

In the present study, the performance of surface flow constructed wetlands (SFCWs) added with different dosage of biochar (group A 0%, group B 10%, group C 20%; v/v) was investigated, to evaluate the effect of biochar on nitrogen removal of a constructed wetland. No significant difference was observed in NH₄⁺-N removal among three groups even during different seasons. Labile organic carbon released from biochar distinctly enhanced denitrification process, which improved NO₃⁻-N removal efficiency by 4.58% in group B and 10.33% in group C. More importantly, compared with group A, biochar addition increased plant N removal by 82.24% and 192.11% in groups B and C, respectively. This result indicated that biochar could increase the accumulation of plant net biomass. In addition, TN removal of group A was much lower at low temperature (4.9 °C). However, no obvious influence of temperature on TN removal was observed in groups B and C with biochar addition. Microbial community analysis showed that, compared with that in group A, the total relative abundance of the main denitrification bacteria (Proteobacteria, Firmicutes, and Bacteroidetes) increased by 0.81% in group B and 13.63% in group C. These results provide a reasonable strategy for improving the performance of SFCWs under cold climate.

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