Assessment of leached heavy metals from construction and demolition waste

Abstract

Construction and demolition waste (CDW) is a substantial environmental concern due to the presence of heavy metals that leach into soils and groundwater. This study investigates the concentrations and spatial migration patterns of heavy metals leached from CDW at a construction site in Kumasi, Ghana. Samples of CDW and underlying soil were collected and analyzed for heavy metals, including lead (Pb), arsenic (As), zinc (Zn), copper (Cu), manganese (Mn), and cadmium (Cd). The findings of the study indicate that the CDW largely consists of sand, which helps leachate move easily. Inverse distance weighting (IDW) interpolation and radial basis function (RBF) neural network modelling were used to predict the vertical and horizontal spread of contaminants. Results show that Cu, Zn, and Mn have higher mobility, while Pb and As tend to stay localized. The mobility raises environmental risks such as soil degradation and threats to plant and microbial life. The study additionally recommends regulatory reforms, sustainable construction practices, and chemical stabilization to reduce the environmental impacts of CDW leachates.