Compacted artificially cemented soil-acid leachate contaminant interactions: Breakthrough curves and transport parameters

The transport of contaminants through compacted artificially cemented soil subjected to acid leachate contaminant percolation was analyzed by means of laboratory column tests. The effect of cement content, degree of acidity and hydraulic gradient were evaluated after permeation of several pore volumes of acid leachate contaminant flow through the soil. The pH, electric conductivity and solute breakthrough curves were considered throughout the study. The results showed that the increase of cement content increases the solute pore volumes needed before breakthrough occurred. An increase of the degree of acidity of the percolate and of the hydraulic gradient cause a reduction in the pore volumes needed before breakthrough occurred. The larger the soil cement content, the longer the time required to reach maximum effluent solute concentration. The hydraulic conductivity slightly increased due to cement addition and reduced with increasing degree of acidity of the percolate. Finally, it is possible to state that cement addition to the soil was responsible for increasing retardation coefficient (R) and distribution coefficient (kd) values, meaning that the artificially cemented soils have higher capability to retard the propagation of the contamination and amplified affinity with dissolved acid contaminant.