Experimental Study of Nitrogen Removal Efficiency of Layered Bioretention Under Intermittent or Continuous Operation

Abstract

Non-point source pollution has increasingly impacted water pollution in cities with the improvement of controlling point-source pollution [1]. Storm-water runoff contains excess nutrients that contribute to the process of eutrophication of surface water, resulting in the degradation of the quality of drinking water and recreational water. Monitoring results of 61 lake (reservoir) nutritional status from the Chinese environmental report of 2015, eutrophication, nutrition, and oligotrophic lakes (reservoirs) were 23%, 67%, and 10%, respectively [2]. As one of the major nutrients in storm runoff, nitrogen mainly comes from lawn fertilizers, fallen leaves, grass clippings, Pol. J. Environ. Stud. Vol. 26, No. 3 (2017) AbstractThe structural configuration of bioretention plays an important role in the consumption and purification of nitrogen pollutants in rainfall runoff. Three layered bioretention tanks -7#, 9#, and 10# -with artificial packing layers of fly ash mixing sand, blast furnace slag, and planting soil, respectively, were selected for intermittent and continuous operational tests. All load-reduction rates of nitrogen pollutants for intermittent running test exceeded 40% in three tanks, and tank 7# showed >70%. Moreover, the effluent pollutant concentration of 7# increased with time, whereas those of 9# and 10# fluctuated and then decreased slowly. The correlation model between TN removal and its influencing factors was established using the partial least regression method. Modeling analysis suggested that the filler type was the most important factor affecting TN removal. TN removal was positively correlated with packing factor and submerged zone height, while it was negatively correlated with antecedent dry time and influent loading. Soil pollutant original content and texture classification were detected before the continuous running test. The percentages of NO 3 -N and NH 3 -N accumulating in three facilities accounted for a total influent load of approximately 77% (7#), 61% (9#), and 43% (10#) when the exhaustion point was reached, demonstrating the relatively poor performance of planting soil.

A Review of Nitrogen Removal for Urban Stormwater Runoff in Bioretention System

“…On the other hand, the addition of carbon source additives to the filter media has shown a beneficial influence by enhancing nitrogen removal efficiency [110,117,127,130]. Furthermore, the use of a saturated zone and increasing its depth has provided additional removal of nitrogen, particularly for NO 3 − [75,124,133]. Significant improvement in nitrogen removal was achieved by combining the saturated and unsaturated zones [90,129].…”

Analysing Bioretention Hydraulics and Runoff Retention through Numerical Modelling Using RECARGA: a Case Study in a Romanian Urban Area

“…From the three types of simulation (continuous, single event, and based on user input) we selected the simulation based on unique event with an excess rainfall (47 mm) in order to evaluate bioretention cell performance under extreme conditions. Some of the variables [34] taken into account to achieve a unique event based on simulations were different for each site individually (except for evapotranspiration, surface, and rainfall) and concern: native soil texture, hydrological conductivity, CN, evapotranspiration, rainfall, percentage of impermeable surface. For rainfall distribution we selected the Hyetograph (time distribution of rainfall) II; for the simulation we introduced the depth of the precipitation corresponding for a period of 24 hours (mm).…”

A comprehensive review on the long-term performance of stormwater biofiltration systems (SBS): Operational challenges and future directions

“…Phosphorus is removed by plants and microbial uptake or absorbed by the filter media (Marvin et al, 2020). Many studies focused on the efficacy and the mechanism involved in nitrogen (Jiang et al, 2017;Tian et al, 2019;Wu et al, 2017) and phosphorus (Chang et al, 2019;Zhang et al, 2018a) removal, but few studies have examined the long-term performance in SBS (Table 2). Previous research suggested that SBS could reduce nutrients after a long-term operation.…”