Enhancing nitrogen removal in constructed wetlands: The role of influent substrate concentrations in integrated vertical-flow systems  

作　　者：Tongtong Liu Da Li Yan Tian Jiajie Zhou Ye Qiu Dongyi Li Guohong Liu Yujie Feng 

机构地区：[1]State Key Laboratory of Urban Water Resource and Environment,School of Environment,Harbin Institute of Technology,No.73 Huanghe Road,Nangang District,Harbin 150090,China [2]Institute of Chemical Engineering in Heilongjiang Province,3#Nanhu load,High Tech R&D Zone of Harbin City,Harbin 150028,China

出　　处：《Environmental Science and Ecotechnology》2024年第5期103-112,共10页环境科学与生态技术（英文）

基　　金：supported by the National Natural Science Foundation of China(21972036);the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2022TS07,No.2022ES202210 and No.2022QG202226);support from the National Natural Science Foundation of China(52300199);the Fundamental Research Funds for the Central Universities(FRFCU5710010522).

摘　　要：Recent advancements in constructed wetlands(CWs)have highlighted the imperative of enhancing nitrogen(N)removal efficiency.However,the variability in influent substrate concentrations presents a challenge in optimizing N removal strategies due to its impact on removal efficiency and mechanisms.Here we show the interplay between influent substrate concentration and N removal processes within integrated vertical-flow constructed wetlands(IVFCWs),using wastewaters enriched with NO_(3)^(-)-N and NH4þ-N at varying carbon to nitrogen(C/N)ratios(1,3,and 6).In the NO_(3)^(-)-N enriched systems,a positive correlation was observed between the C/N ratio and total nitrogen(TN)removal efficiency,which markedly increased from 13.46±2.23%to 87.00±2.37%as the C/N ratio escalated from 1 to 6.Conversely,in NH4þ-N enriched systems,TN removal efficiencies in the A-6 setup(33.69±4.83%)were marginally 1.25 to 1.29 times higher than those in A-3 and A-1 systems,attributed to constraints in dissolved oxygen(DO)levels and alkalinity.Microbial community analysis and metabolic pathway assessment revealed that anaerobic denitrification,microbial N assimilation,and dissimilatory nitrate reduction to ammonium(DNRA)predominated in NO_(3)^(-)-N systems with higher C/N ratios(C/N 3).In contrast,aerobic denitrification and microbial N assimilation were the primary pathways in NH4þ-N systems and low C/N NO_(3)^(-)-N systems.A mass balance approach indicated denitrification and microbial N assimilation contributed 4.12-47.12%and 8.51e38.96%in NO_(3)^(-)-N systems,respectively,and 0.55e17.35%and 7.83e33.55%in NH4þ-N systems to TN removal.To enhance N removal,strategies for NO_(3)-N dominated systems should address carbon source limitations and electron competition between denitrification and DNRA processes,while NH4þ-N dominated systems require optimization of carbon utilization pathways,and ensuring adequate DO and alkalinity supply.

关 键 词：Constructed wetland Nitrogen removal pathway DENITRIFICATION Microbial nitrogen assimilation Enhanced strategy 

分 类 号：X53[环境科学与工程—环境工程]