Nitrogen removal and nitrifying and denitrifying bacteria quantification in a stormwater bioretention system

• Published in: Water research (Oxford) Vol. 47; no. 4; pp. 1691 - 1700
• Main Authors: Chen, Xiaolu, Peltier, Edward, Sturm, Belinda S.M., Young, C. Bryan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-03-2013; Elsevier
• Subjects: Ammonia; Ammonia - metabolism; Applied sciences; Bacteria - genetics; Bacteria - metabolism; Biological and medical sciences; Biological treatment of waters; Bioretention; bioretention areas; Biotechnology; carbon; correlation; Denitrification; denitrifying bacteria; DNA, Ribosomal; drainage; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; genes; Industrial applications and implications. Economical aspects; infiltration rate; Kansas; Nitrate; nitrates; Nitrification; nitrogen; Nitrogen - isolation & purification; Nitrogen - metabolism; nitrogen content; Nitrogen cycling; Other wastewaters; PCR; Pollution; quantitative polymerase chain reaction; Rain; ribosomal DNA; sandy soils; Soil Microbiology; stormwater; Stormwater treatment; Wastewaters; Water Purification - methods; Water treatment and pollution; Kansas; United States; North America; America; Ammonia; Nitrate; Bioretention; Denitrification; Stormwater treatment; PCR; Nitrogen cycling; Sewerage; Water treatment; Nitrogen compounds; Nitrates; Runoff water; Biological purification; Polymerase chain reaction; Nitrogen cycle; Nitrification; Rain water; Poison; Waste water purification; Rain garden
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.12.033

In this study, we examine the biological processes involved in ammonia and nitrate removal in a bioretention system characterized by low infiltration rates and long drainage times. The system removed 33% of influent nitrate and 56% of influent total nitrogen. While influent ammonia concentrations were low (<0.3 mg/L), the bioretention cell also removed ammonia produced within the treatment system. Soil cores collected from the bioretention cell were analyzed for total 16S rDNA and both nitrification and denitrification genes (amoA, nirS, nirK, norB, and nosZ) using quantitative PCR. Total bacterial 16S rDNA levels in the surface layer were similar to those in very sandy soils. Gene counts for both nitrification and denitrification genes decreased as a function of depth in the media, and corresponded to similar changes in total 16S rDNA. The abundance of denitrification genes was also positively correlated with the average inundation time at each sampling location, as determined by modeling of stormwater data from a three-year period. These results suggest that both nitrification and denitrification can occur in bioretention media. Time of saturation, filter medium, and organic carbon content can all affect the extent of denitrification in bioretention systems.
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► Nitrate removal was observed in a roadside bioretention cell. ► Denitrification resulted from slow infiltration times through cell media. ► Nitrification and denitrification genes were most abundant near the media surface. ► Denitrification gene abundance was correlated with surface inundation extent.