Stabilization of Pb²⁺ and Cu²⁺ contaminated firing range soil using calcined oyster shells and waste cow bones

Pb²⁺ and Cu²⁺ contamination at army firing ranges poses serious environmental and health risks to nearby communities necessitating an immediate and prompt remedial action. In this study, a novel mixture of calcined oyster shells (COSs) and waste cow bones (WCBs) was utilized to immobilize Pb²⁺ and Cu²⁺ in army firing range soils. The effectiveness of the treatment was evaluated based on the Korean Standard leaching test. The treatment results showed that Pb²⁺ and Cu²⁺ immobilization in the army firing range soil was effective in significantly reducing Pb²⁺ and Cu²⁺ leachability upon the combined treatment with COS and WCB. A drastic reduction in Pb²⁺ (99%) and Cu²⁺ leachability (95%) was obtained as compared to the control sample, upon treatment with 5wt.% COS and 5wt.% WCB. The combination treatment of COS and WCB was more effective for Pb immobilization, than the treatment with COS or WCB alone. The 5wt.% COS alone treatment resulted in 95% reduction in Cu²⁺ leachability. The SEM-EDX results suggested that Pb²⁺ and Cu²⁺ immobilization was most probably associated with the formation of ettringite, pozzolanic reaction products and pyromorphite-like phases at the same time.