Investigation of removal of flouride ion from waters using waste sludge and natural materials

The source of fluoride ion in water environments results from natural formations and industrial effluents such as electronics, glass, aluminum and steel. Depending to its concentration, fluoride ion can cause harmful effects on aquatic environment and human bodies such as dental and/or skeletal florosis and toxic effects. In this study, the role of removal of fluoride ion by some un-tested natural materials such as pumice, bentonit and perlite, an industrial sludge as bauxite sludge provided from Seydişehir Aluminum Plant and alum sludge and rapid filter top side material obtained from Kağıthane and Ömerli drinking water treatment plants of Istanbul is investigated. To make a comparison and understand the mechanism of fluoride ion removal, some pure aluminum compounds such as aluminum sulfate, aluminum hydroxide, aluminum oxide and metallic aluminum powder has been used. Totally 10 materials has been tested in the removal studies. Batch type experimental studies were conducted in order to get information about fluoride removal capabilities from low- and high-content fluoride waters, the effect of the activation/regeneration treatment of different materials, and the effects of some anions apart from fluoride on the removal. Pumice and bentonite are found to be inefficient on removal of fluoride ion even with activation and regeneration treatments. Contrarily, following the activation treatment, bauxite sludge and perlite had enriched capability. An excellent removal was obtained with 103°C dried alum sludge samples from drinking water treatment plants. By alum sludge being a waste type, up to 90% removal was achieved depending to dosage and particle size. In addition to low-content fluoride works, high-content fluoride wastewaters from some type of industrial facilities were tested by alum sludge samples, and satisfactory removal efficiencies were received. Key Words: Fluoride, Removal of Fluoride, Alum Sludge, Adsorption, Natural Materials