Insight into barrier mechanism of fly ash-bentonite blocking wall for lead pollution in groundwater

[摘要] Groundwater barriers are extensively used for absorbing and blocking heavy-metal contaminants in groundwater. Experiments were conducted to characterize and evaluate the adsorption and migration of Pb(II) through a novel fly ash-bentonite blocking wall. Laboratory analyses included column diffusion, digestion and centrifuge tests to determine the permeability, adsorption, diffusion, and form of Pb(II). By diffusion and column tests, the effective diffusion coefficient of the blocking wall was estimated to be 4.47 x 10(-10) m(2) s(-1) and the stable seepage velocity of Pb(II) was obtained to be 3.55 x 10(-9) m s(-1). These tests were used to determine the service life of the fly ash-bentonite mixture, which is shown to be superior to other bentonite mixtures, including silt, loess-silt, and kaolin. The service life is a function of the thickness, retardation factor, design breakthrough concentration, and upstream head.

[发布日期] 2020-11-01

[关键词] Fly ash-bentonite;Barrier mechanism;Service life;Centrifuge test