Influence of Seawater Temperature and Organic Matter on Iron Elution from a Mixture of Steelmaking Slag and Composts

Seaweed depletions in coastal areas of barren grounds are serious problems in Japan and other parts of the world. The lack of dissolved iron is one of the possible reasons for barren grounds. We have developed a method for restoration of seaweed beds using the mixture of steelmaking slag and composts including humic substances. The influences of seawater temperature and organic matter on the iron elution from the mixture were investigated by iron elution test in seawater in this study. It was found that the iron elution rate from the mixture accelerated as temperature increased. Meanwhile, the powdered bamboo and powdered bamboo coal char were mixed with steelmaking slag and composts used for iron elution test. The amount and the rate of iron elution in seawater became larger by mixing bamboo and its coal char with the slag-compost sample. It was also confirmed that the addition of organic matter could promote iron elution from steelmaking slag.