Kinetics and modeling of trace metal leaching from bottom ashes dominated by diffusion or advection

Ke Yin; Wei-Ping Chan; Xiaomin Dou; Grzegorz Lisak; Victor Wei-Chung Chang

doi:10.1016/j.scitotenv.2020.137203

Kinetics and modeling of trace metal leaching from bottom ashes dominated by diffusion or advection

Sci Total Environ. 2020 Jun 1:719:137203. doi: 10.1016/j.scitotenv.2020.137203. Epub 2020 Feb 8.

Authors

Ke Yin¹, Wei-Ping Chan², Xiaomin Dou², Grzegorz Lisak³, Victor Wei-Chung Chang⁴

Affiliations

¹ Department of Environmental Engineering, School of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 230017, Jiangsu Province, China. Electronic address: yinke@njfu.edu.cn.
² Residue and Resource Reclamation Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore.
³ Residue and Resource Reclamation Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore. Electronic address: g.lisak@ntu.edu.sg.
⁴ Department of Civil Engineering, 23 College Walk, Monash University, Victoria 3800, Australia. Electronic address: victor.chang@monash.edu.

PMID: 32114221
DOI: 10.1016/j.scitotenv.2020.137203

Abstract

Leaching kinetics of trace metals from incineration bottom ashes (IBA) under diffusion and advection were investigated through leaching tests of compacted granulars of IBAs and their packed columns with seawater eluent for 64 days and 26 days, respectively. Metal fluxes were distinct among species while linearily decreased at log-log scales as a function of time. Short-term environmental risks for Cu, Ni and Pb were identified under advection. The metal leaching behavior generally followed the pseudo-second order under diffusion, while the pseudo-first order kinetics under advection. Investigated metals may be further identified as diffusion- (As, Cd, Cr, Sb) and advection-dominant species (Ba, Cu, Ni, Pb, Zn) according to their fluxes, which interestingly corresponded to the low- (5.19-147.90 mg·kg^-1) and high-value (116.46-2398.44 mg·kg^-1) of their metal distribution from IBAs, respectively. Considering the general higher metal release, decay models were employed to simulate the column leaching results. Particularly, Type-II model based on two-site assumptions fit much better to the experimental data, unveiling significant yet retarded release (in 1-2 pore volumes) of certain metals from the slow-reaction sites. Further investigation on the release of bulk parameters unveiled that, there existed rebounded leaching rates primarily ascribed to the IBA heterogeneity.

Keywords: Decay model; Diffusion and advection; Environmental impact; Kinetic modeling; Metal leaching rate.