Nitrogen Removal from Urban Stormwater Runoff through Layered Bioretention Columns

• Published in: Water environment research 2007-11, Vol.79 (12), p.2404-2411
• Main Authors: Hsieh, Chi-hsu, Davis, Allen P., Needelman, Brian A.
• Format: Article
• Language: English
• Subjects: ammonia; Applied sciences; Aqueous solutions; bioretention; Chemicals; Conservation of Natural Resources - methods; eutrophication; Exact sciences and technology; Ion exchange; Minerals; Mulches; Natural water pollution; nitrate; Nitrate content; Nitrates; Nitrification; Nitrogen; Nitrogen - chemistry; Nitrogen - isolation & purification; Nonpoint source pollution; Organic soils; Pollutants; Pollution; Quaternary ammonium compounds; Rain; Rainwaters, run off water and others; Research Papers; runoff; Soil biochemistry; Soil pollution; Soils; Stormwater; Stormwater management; Urban areas; Water Movements; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water pollution; Water Purification - instrumentation; Water Purification - methods; Water quality; Water treatment and pollution
• ISSN: 1061-4303; 1554-7531
• DOI: 10.2175/106143007X183844

Bioretention is a low-impact technology used for the treatment of stormwater runoff in developed areas. The fates of mineral nitrogen compounds in two bioretention columns (RP1 and RP2) with different media-layering characteristics were investigated under multiple loadings of simulated urban runoff. The immediate capture of nitrogen was evaluated, with nitrogen transformation reactions that occurred during the drying periods between rainfall events. A greater proportion of ammonium was removed from runoff in RP2 (68 ± 16%), which had a high permeability layer over a lower permeability layer, than in RP1 (12 ± 6%), which had the inverse configuration. Both column systems demonstrated nitrate export (9 ± 32% and 54 ± 22% greater than input for RP1 and RP2, respectively), attributed to washout of nitrate resulting from nitrification processes between runoff loading events. Bioretention media with a less permeable bottom soil layer could form an anoxic/anaerobic zone for promoting nitrification/denitrification processes.