Abstract
This study evaluated a hydroxyapatite synthesized from waste materials to remove fluoride from wastewater of Gero hot spring containing chloride ion with high level. In addition, this study investigated the mechanisms of fluoride removal by the apatite, the suitable condition of removal treatment, and the capability of reuse of apatite. The apatite could remove fluoride from the wastewater of hot spring below the Environmental Quality Standards for Water Pollution in Japan. The capacity of fluoride removal by apatite was higher than those previously reported. Fluoride sorbed on the apatite was chemically stable within pHs of 2 to 8, and 80% of fluoride removed by apatite was attributed to the precipitation of fluorapatite. The optimum treatment conditions of fluoride removal were the addition ratio of 2 g/L and the treatment time of 5 min. However, the reuse of apatite could not result in the fluoride removal below the standard.
