| 摘要 |
PROBLEM TO BE SOLVED: To obtain granulated material containing trivalent chromium in which hexavalent chromium and the other heavy metals being the contents of either sludge contained in solidified cement or stuck thereto or soil are not eluted by rain water or the like. SOLUTION: Harmful hexavalent chromium contained in sludge or soil is modified into harmless trivalent chromium by FeSO4 . Then, cement is added to the modified sludge or soil and the mixture is kneaded and granulated. Trivalent chromium and unreacted hexavalent chromium are stably contained into cement. Accordingly, even if chromium is exposed to permeated rain water, it is not eluted and therefor granulated material is made harmless. Therefore, dumping disposal to a landfill is enabled because chromium contained in the above granulated material is harmless and is not eluted. |
