Abstract
This study analyzed the adsorption mechanism and temporal performance of permeable reactive barriers (PRB) filled with bamboo charcoal-zeolite mixtures, employing physical and mechanical testing, static batch and dynamic column experiments, microscopic characterization analysis, and groundwater numerical simulation. When bamboo charcoal (particle size > 0.18 mm) and zeolite (particle size > 0.5 mm) were mixed at mass ratios of 1:10 to 3:10, the mixture not only effectively removed cadmium from groundwater but also exhibited favorable permeability and shear strength. The adsorption capacity of the bamboo charcoal-zeolite mixture for cadmium increased with increasing bamboo charcoal proportion and decreasing particle size; the breakthrough and exhaustion times of PRB columns decreased with increasing groundwater flow rate and cadmium concentration. The cadmium removal process by the bamboo charcoal-zeolite mixture primarily involved complexation reactions, chelation, and ion exchange reactions. In cadmium-contaminated groundwater sites, the effective operational lifespan of PRB increased with greater wall thickness and slower groundwater flow velocity.
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China Environmental Science 2024, 44(10)
The Experimental Study of Cadmium Contaminated Groundwater Remediation by Permeable Reactive Barrier with Bamboo Charcoal-Zeolite Mixture
LI Zi-bang¹, ZHANG Liang², LIU Hao³, GONG Xing¹*
¹School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China
²Yangtze River Survey and Technology Research Institute of the Ministry of Water Resources, Wuhan 430011, China
³Guangdong Yue Road Survey and Design Co., Ltd., Guangzhou 510630, China
Abstract
This study investigated the adsorption mechanism and long-term performance of a permeable reactive barrier (PRB) filled with bamboo charcoal-zeolite mixture for remediating cadmium-contaminated groundwater, utilizing a comprehensive approach that integrated physicomechanical testing, static batch and dynamic column experiments, microscale characterization, and numerical groundwater simulation. The mixture of bamboo charcoal (particle size > 0.18 mm) and zeolite (particle size > 0.5 mm) at mass ratios ranging from 1:10 to 3:10 demonstrated effective cadmium removal capability while maintaining favorable permeability and shear strength characteristics. The adsorption capacity of the mixture increased with higher bamboo charcoal content and smaller particle sizes. Column experiments revealed that breakthrough and exhaustion times decreased with increasing groundwater flow rates and cadmium concentrations. Mechanistic analysis indicated that cadmium removal primarily occurred through complexation, chelation, and ion exchange reactions. Furthermore, numerical modeling demonstrated that thicker PRB configurations and slower groundwater flow velocities extended the effective operational lifespan at cadmium-contaminated sites.
Keywords: Groundwater; Cadmium pollution; Permeable reactive barrier; Long-term effectiveness