| Summary: | 碩士 === 中臺科技大學 === 安全與防災科技研究所 === 100 === Contaminated sediments in the harbors remain being a significant issue during dredging operations. Numerous methods have been suggested in recent years for remove, treating and beneficial uses of harbor sediments. In this research, the basic characteristics and the geochemistry of metals in the sediments were studied, and which were subjected to pH‐dependent leaching test, percolation test and column test. The results of experimental leaching tests of harbor sediments are compared with computer calculations. This computer program allows to predict the metal concentrations and the pH of leaching solution at equilibrium, along with the minerals that precipitate and the organic characteristics react with the metal ions forming into stable organic metal compounds.
The result of laboratory research showed that the content of heavy metals contaminants can not meet the Sediment quality standards requirements, thus further treatment such as chemical washing and stabilization/modification are needed before deposition and recycling. Results from the chemical washing (extraction) technique showed that under 0.1M Citric Acid and 1 N HCl as reagents with a sediment/reagent ratio of 1/10, contact time of 60 minutes, the Cu removal efficiency was 2% and 45%, respectively; the Zn removal efficiency was 78% and 84%, respectively; the Ni removal efficiency was 48% and 72%, respectively; the Pb removal efficiency was 20% and 57%, respectively; the Cr removal efficiency was 28% and 43%, respectively; Besides that, stabilization/modification processes (adding with soil amelioration products) can make the heavy metal containing sediment to be low-matrix leach ability and which might be reused as construction material. Thus, this research projects might provide a basic understanding, and the statistic correlation among the sediment characteristics, metal concentration and the possible controlling factors.
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