Evaluation of solidification/stabilization in arsenic-contaminated soils using lime dust and cement kiln dust

Abstract

Contamination of soil and underground waters is a common environmental problem. Arsenic is a toxic chemical used widely in chemical industrial applications. New methods such as solidification/stabilization developed as requiring much space and propagation of materials in primary treatment methods caused interim methods for disposal of contamination to become inappropriate. The aim of this study was to investigate the use of cement kiln dust (CKD) and lime dust in solidification/stabilization process for arsenic-contaminated soils. Laboratory-prepared samples spiked with arsenic were made and treated with CKD and lime dust ranging from 15 to 30 wt% and 5–15 wt%, respectively. The effectiveness of treatment was evaluated at 28 days of curing based on the solidification/stabilization tests including unconfined compression test, toxicity characteristic leaching procedures (TCLP), and scanning electron microscopy (SEM). The results show that, though lime dust has a minor effect on samples strength, it has a significant effect on arsenic sorption. On the other hand, CKD causes immobilization of arsenic in the soil, as well as a major effect on soil strength. Based on the results, samples with 20 wt% CKD and 5 wt% lime dust have the optimized correlation between strength and acceptable level of Arsenic leakage in the TCLP test.