Remediation of arsenic-contaminated soils via waste-reclaimed treatment agents: Batch and field studies

The potential of three different waste-reclaimed treatment agents (WRTAs) for removing arsenic was evaluated via laboratory-scale batches, column experiments, and field tests. WRTA1 was synthesized using acid mine drainage sludge (AMDS), cement, and sand. WRTA2 and WRTA3 were synthesized by adding fly ash or Ca(OH)₂, respectively, to WRTA1. The maximum adsorption capacities of WRTA1, WRTA2, and WRTA3 for As(III) using the Langmuir model were 16.6 mg g⁻¹, 14.5 mg g⁻¹, and 20.6 mg g⁻¹, respectively, and for As(V) were 29.6 mg g⁻¹, 27.3 mg g⁻¹, and 31.3 mg g⁻¹, respectively. The pseudo-second-order equation for the adsorption of As(III) and As(V) fit the kinetics data well. The column study showed that the WRTAs are very effective adsorbents and exhibit > 80% removal of As from the contaminated soil. The inhibition of As accumulation in plants (i.e., rice, chili, and sesame) by the WRTAs was evaluated and showed a 96% inhibition in As accumulation in chili roots for WRTA2. The suggested WRTAs are promising agents for the removal of As and heavy metals from heavily contaminated agricultural soil.