Hydrology and rainfall runoff pollutant removal performance of biochar-amended bioretention facilities based on field-scale experiments in lateritic red soil regions

Yepeng Mai; Guoru Huang

doi:10.1016/j.scitotenv.2020.143252

Hydrology and rainfall runoff pollutant removal performance of biochar-amended bioretention facilities based on field-scale experiments in lateritic red soil regions

Sci Total Environ. 2021 Mar 20:761:143252. doi: 10.1016/j.scitotenv.2020.143252. Epub 2020 Nov 4.

Authors

Yepeng Mai¹, Guoru Huang²

Affiliations

¹ South China University of Technology, Guangzhou 510641, China.
² South China University of Technology, Guangzhou 510641, China; State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510641, China; Guangdong Engineering Technology Research Center of Safety and Greenization for Water Conservancy Project, Guangzhou 510641, China. Electronic address: huanggr@scut.edu.cn.

PMID: 33183819
DOI: 10.1016/j.scitotenv.2020.143252

Abstract

Bioretention has been found to lower the effluent loads of various pollutants from rainfall runoff. However, it is still a challenge to effectively use bioretention for rainfall runoff control in lateritic red soil regions where have high rainfall intensity and low soil infiltration capacity. Hence, in this study, the hydrologic performance and rainfall runoff pollutant removal capacity of field-scale biochar-amended bioretention facilities were tested with four rainfall recurrence periods under different biochar distributions, internal water storage (IWS) zone heights, and exfiltration conditions. The results confirmed that incorporation of biochar into planting soil would improve its water content raising capacity (WCRC), especially when the biochar was uniformly mixed with the lateritic red soils. Besides, more infiltrating from the planting soil layer and higher IWS zone heights effectively enhanced WCRC of the stone chip packing layer. For runoff volume control, adding biochar and increasing the IWS zone height could effectively improve runoff volume control capacity. Besides, the unlined bioretention had a higher runoff volume control capacity than lined bioretention. Considering runoff pollutant removal performance, biochar could contribute to significantly improving the runoff pollutant event mean concentration removal rate (R_c) of nutrient pollutants (TN, NO₃-N, NH₃-N, and TP). The average runoff pollutant load removal rate (R_l) of different biochar distributions decreased as follows: biochar was uniformly mixed with the lateritic red soils > biochar was stratified with the lateritic red soils > biochar was excluded in the planting soil layer. The average R_c and average R_l of all pollutants except COD under different IWS zone heights decreased as follows: 40 cm > 20 cm > 0 cm. Meanwhile, the average R_l of the lined bioretention with an IWS zone height of 0 cm was lower than that of the unlined bioretention. Overall, higher rainfall recurrence periods would reduce the treatment capacity of bioretention facilities.

Keywords: Biochar; Bioretention; Internal water storage zone; Lateritic red soil regions; Runoff pollutants removal; Runoff volume control.

MeSH terms

Charcoal
Environmental Pollutants*
Hydrology
Rain
Soil*
Water Movements

Substances

Environmental Pollutants
Soil
biochar
Charcoal