title: Surface-modified biochar in a bioretention system for Escherichia coli removal from stormwater.
abstract: Bioretention systems have been recommended as one of the best management practices for low impact development for water recycling/reuse systems. Although improvement of the stormwater quality has been reported regarding pollutants eliminations such as suspended solids and heavy metals, a substantial removal of indicator bacteria is required for possible non-potable reuse. This study investigated the efficiency of wood biochar with H2SO4-, H3PO4-, KOH-, and amino-modifications for E. coli removal from synthetic stormwater under intermittent flow. The H2SO4-modified biochar showed a specific surface area of 234.7 m2g-1(approximately double the area of original biochar), whereas a substantial reduction in surface area was found with amino-modified biochar. The E. coli removal (initial concentration of 0.3-3.2 × 106CFU mL-1) by modified biochars as filter media was very promising with, for example, over 98% removal efficiency in the first 20 pore volumes of stormwater infiltration and over 92% removal by the end of the second infiltration cycle. Only a small portion of E. coli attached on the modified biochars (<0.3%, except KOH- and amino-modified biochars) was remobilized during the drainage phase of intermittent flow. The high removal capacity and stability against drainage were attributed to the high surface area, porous structure, and surface characteristics (e.g. hydrophobicity and O-containing functional groups) of the biochars. Thus, the H2SO4-modified biochar appeared to give the best treatment performance.
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Abbe Y T
authors.initials: AY
authors.lastname: Lau
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. Electronic address: dan.tsang@polyu.edu.hk.
authors.forename: Daniel C W
authors.initials: DC
authors.lastname: Tsang
authors.affiliation: Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Nigel J D
authors.initials: NJ
authors.lastname: Graham
authors.affiliation: Korea Biochar Research Center & School of Natural Resources and Environmental Science, Kangwon National University, Chuncheon 24341, South Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Li
mesh_terms: D002606:Charcoal; D004926:Escherichia coli; D005374:Filtration / Q000379:methods*; D019216:Metals, Heavy; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000382:microbiology*
chemical_list: D002606:Charcoal; D019216:Metals, Heavy; D062065:Wastewater; C540010:biochar
keywords: Bacteria removal; Bioretention systems; Designer biochar; Intermittent flow; Stormwater harvesting