Abstract
Aeration and plants exhibit influence on the water purification performance in constructed wetlands (CWs). However, the interaction between aeration and plants on enhancing performance of domestic sewage treatment is unclear. Our study aims to optimize the combination of aeration position and plant species, promoting the extensive and effective application of CWs. Herein, six horizontal subsurface flow (HSSF) CWs small scale plots were established and divided into two groups according to the plant (i.e., Canna indica and Iris sibirica). To adjust the distribution of dissolved oxygen (DO) in CWs, each group had three plots of HSSF CWs. One plot was aerated at the bottom of the first quarter of the filtration chamber, one plot was aerated at the bottom of the inflow chamber, and the remaining plot was not aerated as a control. Results showed that aeration at the bottom of the first quarter filtration chamber could contribute to the highest removal efficiency of chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and total nitrogen (TN). The COD, NH4+-N, and TN removal percentages decreased with the drop in temperature. However, the plot aerated at the bottom of the first quarter filtration chamber with I. sibirica exhibited the best average CODCr, NH4+-N and TN removal percentages in both the warm season (83.6%, 82.7% and 76.8%) and the cool season (66.3%, 44.1% and 43.8%). Therefore, this study indicated that the combination of aerating at the bottom of the first quarter filtration chamber and planting with I. sibirica in the HSSF CWs would be a promising way forward for wastewater treatment, especially in low temperature seasons.
Highlights
The carbon, nitrogen and phosphorus concentrations in the water environment are mainly affected by the anthropogenic emissions [1,2], which are responsible for the eutrophication of water bodies
Constructed wetlands (CWs) planted with I. sibirica exhibited significantly higher removal efficiencies of CODCr and NH4 + -N than those planted with C. indica did
horizontal subsurface flow (HSSF) CWs planted with I. sibirica showed better total nitrogen (TN) removal efficiency than those planted with C. indica did in cool season
Summary
The carbon, nitrogen and phosphorus concentrations in the water environment are mainly affected by the anthropogenic emissions [1,2], which are responsible for the eutrophication of water bodies. Constructed wetlands (CWs) are complex ecosystems composed of plants, microorganisms and substrates to remove contaminants [3]. CWs have the advantages of low investment cost, convenient operation and management, high ecological benefits, good pollutant removal effects, and wide applications [4]. CWs can be classified as surface flow and subsurface flow systems, which are depended on water levels. Subsurface flow CWs are divided into two types: vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF) systems [5]. The pollutant types, contaminant concentrations, geographical environment etc. Should be taken when selecting the type of CWs The pollutant types, contaminant concentrations, geographical environment etc. should be taken when selecting the type of CWs
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