ELUTION CHARACTERISTICS OF POLLUTANTS IN CEMENT-MIXED AND DEHYDRATED CONTAMINATED SEDIMENT

Authors have developed a technique called the cement-mixing and mechanical dehydration method (CMD) that produces a concrete-like material from slurry by adding cement and dehydrating it with high pressure. In the study, the CMD was applied to immobilize pollutants in marine bottom sediment, such as heavy metals, tri-butyl tin (TBT) and tri-phenyl tin (TPT). A series of leaching test and the unconfined compression test were performed to investigate the elution characteristics of pollutants from the treated contaminated sediment prepared by the CMD. The main conclusions obtained form the study are; 1) the CMD is effective for increasing the strength of contaminated sediment, 2) the elution of heavy metals from the contaminated sediment treated by the CMD can be restrained to meet the Environmental Quality Standards for Water Pollution of Japan, and 3) the elution of TBT and TPT depends on the pH of treated contaminated sediment and it can be expressed by an exponential function of pH, in the alkaline pH range.