Abstract
Many harmful substances are hidden around us. Waters and soils polluted with harmful metal ions are particularly dangerous to the living organisms. A large amount of harmful metal ions might be diffused in the water environments when the great earthquake occurred in the Eastern Japan in March 2011. The purpose in the present study is to verify the removal of various metal ions from wastewaters in the water environments by the porous concrete containing baking bone dust (mainly natural hydroxyapatite; HAP) and steel slag as a industrial by-product. The porous concrete showed more than 10N/mm2 strength and 30% air space rate. We investigated the removal of various metal ions from the artificial wastewater by the porous concrete. As a result, the porous concrete containing 10% baking bone dust efficiently absorbed lead ion, cadmium ion, copper ion, ferric ion and chromium ion. Manganese ion, nickel ion and strontium ion were also moderately absorbed in the porous concrete. Moreover, we examined the absorption of ferric ion and manganese ion eluted from the bottom sediment in Yashima-bay of Kagawa prefecture. The porous concrete significantly absorbed metal ions eluted from the bottom sediment. To confirm the binding ability of the porous concrete toward metal ions in real sea, the amounts of metal ions bound to the porous concrete were measured after placement of the porous concrete in Yashima-bay. As a result, 2-3years later of the placement of the porous concrete, the efficient bindings of lead ion, cadmium ion, copper ion, ferric ion, manganese ion and zinc ion to the porous concrete were observed. These results suggest that the porous concrete containing baking bone dust seem to be available to remove metal ions from the water environments. Also, the useful metal ions absorbed in the porous concrete can be recovered easily with acid treatment.
