Bioretention cell incorporating Fe-biochar and saturated zones for enhanced stormwater runoff treatment. (December 2019)

• Record Type: Journal Article
• Authors: Xiong, Jiaqing; Ren, Sihui; He, Yifan; Wang, Xiaochang C.; Bai, Xuechen; Wang, Jiaxuan; Dzakpasu, Mawuli
• Is Part Of: Chemosphere. Volume 237(2019)
• Publication Date: 2019-12
• Subjects: Runoff pollution -- Bioretention -- Iron-modified biochar -- Amended media -- Nutrients; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.124424
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Nitrogen (N) and phosphorus (P) removal in conventional bioretention systems is highly variable. Therefore, five novel experimental columns with different media configurations and constituents, and incorporating a saturated zone were developed and assessed to optimize the removal of N, P and other nutrients. Three types of media composed of the conventional mixed sand and soil media (T1 ), biochar-amended media (T2 ), and iron-coated biochar (ICB)-amended media (T3 ) were evaluated. Two of the experimental columns were designed with double-layer configurations, while the other three were of a single-layer structure. Removal efficiencies of nutrients in the experimental columns were evaluated and compared using simulated runoff. Also, the effect of media depth on the retention of P and denitrifying enzyme activity (DEA) in the bioretention columns were evaluated. The experimental column only filled with T3 showed the best performance for COD, ammonia (NH4 + -N) and total phosphorus (TP) removal (94.6%, 98.3% and 93.70%, respectively), whereas columns filled with T2 performed poorly for TP removal (57.36%). For the removal of nitrate (NO3 − -N) and total nitrogen (TN), the columns using a single-layer and only filled with either T3 or T2 exhibited the best performance (93% and 97% TN removal, respectively). Overall, this study demonstrates that our proposed single-layered bioretention cell only filled with T3 and incorporating a saturated zone effectively improves the runoff quality, and can provide a new bioretention cell configuration for efficient stormwater treatment. Highlights: Iron-coated biochar (ICB) increased the adsorption of the media to phosphorus. ICB supplied the carbon source for the denitrification reaction. Single-layered experimental columns were more conducive to the removal of nitrate. Denitrifying enzyme activity of media is higher at the media boundary.