Engineered Bioretention for Removal of Nitrate from Stormwater Runoff

Abstract

A bioretention unit is a simple, plant‐ and soil‐based, low‐impact treatment and infiltration facility for treating stormwater runoff in developed areas. Nitrate, however, is not attenuated in conventional bioretention facilities. Thus, this study systematically evaluated a reengineered concept of bioretention for nitrate removal via microbial denitrification, which incorporates a continuously submerged anoxic zone with an overdrain. Experimental studies were performed in four phases. In the first two phases, column studies demonstrated that, overall, newspaper is the best solid‐phase electron‐donor substrate for denitrification out of the set studied (alfalfa, leaf mulch compost, newspaper, sawdust, wheat straw, wood chips, and elemental sulfur) based on superior nitrate removal and effluent water quality. The nitrate loading and hydraulic loading studies in the second phase provided design information. In the third phase, system viability after 30‐ and 84‐day dormant periods was evaluated in column studies, demonstrating that newspaper‐supported biological denitrification should be effective under conditions of intermittent loadings. Finally, in the fourth phase, pilot‐scale bioretention studies demonstrated the effectiveness of the proposed design, showing nitrate plus nitrite mass removals of up to 80%. These results indicate that engineered bioretention for the removal of nitrogen from stormwater runoff has the potential for successful application as an urbanstormwater treatment practice.

Low Impact Development Practices: A Review of Current Research and Recommendations for Future Directions

“…The creation of NO 3 -N through mineralization and nitrification of other forms of nitrogen in between infiltration events has also been cited as a possible mechanism for the low retention of NO 3 -N (Davis et al 2001). Several researchers have performed studies designed to increase the ability of a bioretention area to treat NO 3 -N. An alternative design was proposed that involved raising the underdrain outlet pipe, to create a saturated zone in the bottom of the garden (Kim et al 2003). The resulting condition would then be conducive to denitrification reactions, where NO 3 -N is converted to nitrogen gas (Korom 1992).…”

Adsorption of Nutrients from Stormwater Using Sawdust

“…Using renewable resources for contaminant removal through adsorption is becoming more cost-effective method. Some materials have been tested for this purpose, such as sepiolite [11], bittern [12], clinoptilolite [13][14] hardwood mulch [15], and sawdust [16][17][18].…”

“…Nitrite was reached 98.72% removal efficiency with 2.5 mg/L of nitrite and 100% removal efficiency for ammonia with both waste load concentration of 0.5 and 2.5 mg/L after 1 and 1.5 hours hydraulic retention time [18]. Kim [16] selected the different material as potential electron donors to treat stormwater. They performed three sets of experiments: (i) Set 1 consisted of alfalfa, newspaper, and leaf mulch compost, (ii) Set 2 consisted of sawdust, wood chips, and wheat straw, and (iii) Set 3 consisted of small sulfur-limestone, large sulfur-limestone, and large sulfur only particles.…”

“…Based on these results, they chose newspaper, wood chips, and small sulfur-limestone as the best electron donor for their further experiments. In experimental set 2, because of wood chips showed better removal of nitrate along the column length (data not shown), they opted wood chips rather than sawdust [16].…”

Integrated design workflow and a new tool for urban rainwater management

“…The replacement of vegetated areas that provide rainwater interception and storage, often results in an increase in the rate and volume of stormwater runoff (Kim et al, 2003;Mansell, 2003;Whitford et al, 2001). The subsequent urban flooding with increased frequency and severity is exacerbated by the climate change, which causes amplified magnitude of rainfall intensity in some parts of the world (Dore, 2005;Villarreal et al, 2004).…”