Sustainable remediation of arsenic contaminated soils using amended compost

Contaminated land is increasingly becoming an important issue worldwide. Many metal contaminants are persistent in soil for a large number of years. Immobilisation of metals has proven to be a challenging task and a cost-effective, non-invasive and socially acceptable technology is required for its remediation. The effectiveness of different combinations of compost, zeolite and iron oxide treatments (up to 20% w/w) was tested on a contaminated soil with elevated levels of arsenic (34470 mg kg-1) and other metals like Cu, Pb, Zn and Cd. Their effectiveness is evaluated through a series of experiments including batch leaching, greenhouse experiments, sequential extractions and subjecting them to SEM-EDX and XRD analysis. The results illustrated that the combination of 10%compost2%iron oxide and 15%zeolite5%compost has yielded a reduction in the batch leaching of arsenic by 98% compared to the unamended soil. The greenhouse experiments indicated that a higher biomass production was achieved using the combinations 15%compost5%iron oxide and 15%compost5%zeolite amendments. These two combinations have also resulted in a reduced uptake of arsenic in the rye grass (to 2 mg kg-1 dry weight). A standard pseudo total digestion procedure is being carried out to dissolve heavy metals bound to important compost constituents. Overall, this study demonstrated that the combination of iron oxide and/or zeolite with compost increases the effectiveness of remediating arsenic contaminated soil by enhancing plant growth and decreasing plant uptake of arsenic