Enhancing nitrate and phosphorus removal from stormwater in a fold-flow bioretention system with saturated zones

Abstract

The traditional bioretention systems possess a remarkably low nitrogen and phosphorus removal effect. The removal rate fluctuates greatly, and even appears as negative removal of nitrogen and phosphorus. The four simulated bioretention experimental columns with different bilayer media, packing composition and structure were constructed. Based on the traditional fillers, the modified composite fillers with hydroxy-aluminum and modified vermiculite sludge particle (HAVSP) were added. The traditional filler (C1) and the modified composite filler (C2) were added respectively, moreover the saturated zones were set up to enhance the effect of nitrogen and phosphorus removal. Removal of nutrients from experimental columns by simulated runoff efficiency was evaluated and compared. In addition, the effect of media depth on phosphorus retention and denitrifying enzyme activity in bioretention columns was also evaluated. The experimental column #2 filled with C2 had the optimum removal effect on total phosphorus (93.70%), however, the removal effect of total phosphorus by filling C1 experimental columns was insufficient (57.36%). Designed to remove nitrate (NO3−-N) and total nitrogen (TN), the experimental column #4 showed the best performance (83.54% and 92.15%, respectively). In this study, we propose a fold-flow bioretention system by filling HAVSP in combination with saturated zones. The runoff water quality can be effectively improved, and a new bioretention cell configuration can be provided for efficient stormwater treatment.

The Value of Vegetation in Nature-Based Solutions: Roles, Challenges, and Utilization in Managing Different Environmental and Climate-Related Problems

“…Myrtaceae) were both the best-performing species for wet and dry periods. The removal of both TN and nitrate (NO 3 -N) at rates of 83.54% and 92.15%, respectively, was accomplished by using saturated zones in conjunction with the hydroxy-aluminum vermiculite sludge particles (HAVSP), and it was recommended to create a fold-flow BRs [57].…”

Variability of Potential Soil Nitrogen Cycling Rates in Stormwater Bioretention Facilities

“…With the increasing use of LID in urban areas to address stormwater goals, understanding the nutrient transformation processes within these systems is an important component of quantifying the ecological benefits that they provide. Laboratory mesocosm studies have generally reported high retention of sediment, heavy metals, and phosphorus; however, results concerning potential N removal have been more variable [8][9][10][11][12]. Investigations of BRF pollutant removal efficacy at the field scale have shown moderate reductions in N concentrations during simulated storm events (49-90%) [13,14], but patterns during actual storm events have shown a wider range of variability.…”