A novel pilot‐scale tubular bioreactor‐enhanced floating treatment wetland for efficient in situ nitrogen removal from urban landscape water: Long‐term performance and microbial mechanisms

Abstract

In order to strengthen in situ nitrogen removal of urban landscape water, a novel pilot-scale tubular bioreactor-enhanced floating treatment wetland (TB-EFTW) was constructed, and the long-term performance and responsible microbial mechanisms were investigated in this study. The results showed that the system could remove 81.5% nitrogen from the landscape water after 240 days' operation. Moreover, the contribution rate of plant absorption to nitrogen was low (8.3%), which indicated that microbial biotransformation rather than plant absorption played a more key role in nitrogen removal in TB-EFTW system. The declining dissolved oxygen (DO) concentration along the axial direction of tubular bioreactor (TB) resulted in the sequential bacterial community of nitrifying, aerobic denitrifying, and anoxic denitrifying bacteria in the front, middle, and final part of TB. High-throughput sequencing results demonstrated that the internal environment of the system realized the coexistence of nitrifying, aerobic denitrifying and anoxic denitrifying process. The reason was mainly because that oxic-anoxic (O-A) areas were formed in sequence along the axial direction of tubular bioreactor. Overall, a unique advantage in nitrogen removal was achieved in TB-EFTW, which could provide important references for in situ treatment of urban landscape water. • Practitioner points• TB-EFTW strengthened nitrogen removal for in situ urban landscape water treatment. • Microbial conversion played a key role in nitrogen removal of the TB-EFTW system. • The unique distribution of oxic-anoxic (O-A) areas was formed in sequence along the TB. • Nitrification, aerobic, and anoxic denitrification were synergistically involved in the TB.• Key words agriculture; biological treatment; nitrogen removal; surface water

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Nitrogen removal and microbial mechanisms in a novel tubular bioreactor‐enhanced floating treatment wetland for the treatment of high nitrate river water

“…In this research, a tubular bioreactor-enhanced floating treatment wetland (TB-EFTW) was developed for in situ treatment of high nitrogen river water (Cui et al, 2019). The aims of this study were (i) the nitrogen removal efficiency of the TB-EFTW system was investigated and compared with the EFTW system to illustrate its technology advantages; (ii) to reveal the nitrogen removal mechanism in the new system, which mainly included the factors affecting nitrogen removal, and the contribution of plants absorption; and (iii) to understand the microbial mechanism through high-throughput sequencing analysis, as well as correlation analysis between microbial communities and environmental variables.…”