In this study, we carried out several sets of laboratory-based experiments under various conditions in order to develop technically feasible and cost effective ex-situ sediment remediation techniques. The sediment for this study was collected from a sewage sludge contaminated site in western Xiamen Bay, China, in July 2005. The main findings from this study include (1) low pH condition (pH < 5) and large solid-to-liquid ratio (e.g., 1:50) increase metal extraction efficiency by EDTA-2Na, although the efficiency for each metal are different due to chemical properties of each metal and EDTA-2Na; (2) 0.20 M (NH_4)2C_2O_4 + 0.025 M EDTA combination with solid:liquid ratio = 1:50 and 0.50 M NH_4Ac + 0.025 M EDTA combination with solid:liquid ratio = 1:50 are the adoptable methods to extract metal contaminants with respect to extraction efficiency and economical cost; (3) using 0.010M SDS solution with solid:liquid ratio = 1:20 should be avoided because it is much less effective in removal of metals from sediments; (4) using 0.20 M H2_C_2O_4 solution under aeration with solid:liquid ratio = 1:50 yields the best extraction efficiency for Cu (93%), Zn (89%), Cd (79%), Cr (45%) and Ni (66%). But, this method has very low extraction efficiency for Pb (3.4%); and (5) using 0.025 M EDTA solution with aeration and solid:liquid ratio = 1:50 has ～73% extraction efficiency for Pb besides moderate to high extraction efficiencies for other metals (except for Cr) ranging from 37% (Ni) to 94% (Cu). This study provides important and useful information for sediment decontamination technology development.
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