Meat-analysis revealed the factors affecting the function of ecological floating bed in removing nitrogen and phosphorus from eutrophic water

Abstract

Abstract Ecological floating bed (EFB) has been widely used to remove nitrogen and phosphorus from eutrophic water. However, EFB functions largely vary with different studies. Presently it has not been systematically clear what factors affect EFB functions in removing nitrogen and phosphorus from eutrophic water. In this study, we performed a meta-analysis of 169 articles to discuss the effects of EFB characteristics and experimental conditions on EFB function. Results showed that EFB generally decreased nitrogen and phosphorus concentrations in eutrophic water regardless of EFB characteristics and experimental conditions. EFB functions in removing TN, NH4+-N and TP were large when it was constructed by monocots, included 2–3 plant species, had the area of 1.1-3.0 m2, had the coverage of 21%-40%, or had plant density of 21–60 plants/m2. However, NO3−-N removal by EFB was complicated due to the effects of nitrification and denitrification. EFB functions in removing nitrogen and phosphorus from eutrophic water were also affected by experimental conditions, and reached the largest at water temperature of 16–25℃,experimental duration of 31–60 days, long hydraulic retention time (HRT), or aeration. This study indicated that EFB could significantly decrease the concentrations of nitrogen and phosphorus in eutrophic water, and was an effective technology to control water eutrophication.