Remediation of Fine Soil Contaminated with Heavy Metals Using Fishery Waste Products and Starfish (Asterina Pectinifera)

The high-pressure soil washing process is very effective for emergency recovery of heavy metal contaminated soil. However, fine soils with high levels of heavy metals could be generated. This study investigates the stabilization of heavy metals in fine soils using discarded mussel shells, clam shells, and starfish. These materials, processed into natural (-#10 mesh, -#20 mesh) and calcined (-#10 mesh) forms, were added to contaminated soil at 0–10 wt% and wet cured for 28 days. Stabilization efficiency was evaluated through 0.1 M HCl extraction. The stabilization results showed that calcined agents generally exhibited higher efficiency than natural agents. Among the natural agents, the order of stabilization efficiency was starfish > clam shell > mussel shell. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX) analysis confirmed the contribution of pozzolanic products in stabilizing heavy metals. Optimal application rates for the reduction in metal elution of 80% or greater were 10 wt% for natural clam shell, 8 wt% for natural starfish (-#20), 4 wt% for calcined mussel and clam shells (-#10), and 2 wt% for calcined starfish (-#10). These results suggest that discarded shells and starfish can be effectively reused for stabilizing heavy metal-contaminated soil, offering an environmentally friendly solution to waste disposal.