Heavy metal contaminant remediation study of western Xiamen Bay sediment, China: Laboratory bench scale testing results

A surface sediment sample (<5 cm) was collected from a sewage sludge contaminated site (118°02.711′E, 24°32.585′N) within western Xiamen Bay, China, in July 2005 for a sediment decontamination study. A series of laboratory-based experiments under various conditions were performed using chemical complexation reagents (e.g., H2C2O4, EDTA-2Na, etc.) and their combination in order to provide information for sediment remediation technology development. In this study, the results suggest that aeration and agitation of the sediment samples in distilled-deionized water (DDW) have either no or weak (<30%) effect on metal removal, whereas agitation, aeration and rotation of the samples in chemical complexation solutions yield much better metal removal efficiency (up to 90%). A low pH condition (e.g., pH < 3) and a low solid to liquid ratio (e.g., S:L = 1:50) could increase metal removal efficiency. The experimental results suggest that 0.20 M (NH4)2C2O4 + 0.025 M EDTA combination with solid:liquid ratio = 1:50 and 0.50 M ammonium acetate (NH4Ac) + 0.025 M EDTA combination with solid:liquid ratio = 1:50 are the most effective methods for metal removal from the contaminated sediments. This research provides additional useful information for sediment metal remediation technology development.