Decrease of Sulfide in Enclosed Coastal Sea by Using Steelmaking Slag

Currently in Japan, 15 million tons of steelmaking slag as a by-product of the steelmaking process is produced annually. More than 60% of the steelmaking slag is used in civil construction. steelmaking slag has special properties which are presently under-exploited. Therefore, research into the greater utilization of the special characteristics of steelmaking slag in coastal environments has been undertaken over the last 20 years. It is known that steelmaking slag can reduce hydrogen sulfide in seawater. Hydrogen sulfide is highly toxic and fatal to benthic organisms. It also depletes oxygen and generates blue tide. The purpose of this study is to evaluate and demonstrate the effects of removal of hydrogen sulfide in seawater by steelmaking slag. Both the laboratory and the field experiments showed that steelmaking slag removed the hydrogen sulfide from seawater and reduced the concentration of hydrogen sulfide in sediment. The field experiments also indicated that steelmaking slag changed the anaerobic condition of sediment into an aerobic condition. The results imply that effective utilization of steelmaking slag in coastal area restoration can significantly improve the surrounding marine environment.