¶Effective immobilization and reduction in bioavailability of Cd in a L. succinea growing in contaminated sediment by the application of alkali synthesized fly ash based zeolite (FABZ)

In the current study, a highly efficient and cost-effective zeolite derived from fly ash was used for immobilization of cadmium (Cd) in sediment of a pond. The potential of fly ash based zeolite (FABZ) was explored by in-situ amendment practice, including a study plan based on sediment-water microcosm study. The zeolite obtained after acid washing step (fly ash: acid, 1:10 g/mL) followed by the alkali fusion showed the high value of cation exchange capacity (CEC, 13.88 meq/g). The maximum monolayer uptake capacity was found as 145.931 mg/g, indicating the usefulness of FABZ in Cd enriched environment. The sediment treated with 10% FABZ showed remarkable decrease in Cd concentration (about 80%) as compared to the control (0% FABZ). The results of the sequential extraction in exchangeable fraction revealed that Cd level was decreased by 90.72% (10% FABZ) as compared to untreated one, hence successfully decreased the bioavailable Cd. Furthermore, in the muscles of Lymnaea succinea, Cd concentration of 0.87 mg/kg was observed (10% FABZ), which was found six times less than the mollusc of 0% FABZ treated sediment. Thus, prepared FABZ showed its potential to immobilize Cd from sediment and can be used as an economical and feasible method for sediment management at pilot scale.