Simulation of Heavy Metal Removal in Irrigation Water Using a Shell-Derived Biochar-Integrated Ecological Recycled Concrete

Water pollution intensifies water scarcity and poses a significant threat to ecosystems and human health. Construction waste generated by rapid urbanization also imposes a considerable burden on the environment. Fortunately, a large portion of this waste can be efficiently converted into recycled aggregates and reused in various fields including environmental remediation. In this study, three types of eco-recycled concretes (ERC) (Control-ERC, Biochar-ERC-1, and Biochar-ERC-2) were formulated by integrating shell-derived biochar with recycled aggregates. The porosity and water permeability of these concretes were characterized, and their efficacy evaluated in treating polluted water with six primary heavy metals (HMs), i.e., cadmium (Cd), chromium (Cr), arsenic (As), manganese (Mn), lead (Pb), and copper (Cu). Biochar addition significantly enhanced the continuous porosity and water permeability of the concrete, and substantially enhanced its adsorption capacity of HMs. Specifically, Biochar-ERCs removed over 90% of As, Cd, and Mn, and achieved a removal rate exceeding 60% for other HMs, surpassing the performance of Control-ERC. This study not only lays a solid foundation for the wide application of Biochar-ERCs in the field of environmental protection and remediation, but also provides strong technical support and practical examples for advancing the circular economy model of converting waste into resources while addressing the challenge of global water scarcity.