Abstract
Seventy weight percent of CRT (cathode ray tube) panel glass and 30wt% of crushed shell were mixed, and then the particle (Φ5mm) was formed by pressure forming. The particles were sintered at 650°C for 20 minutes. The sintered materials have high adsorption capacity of phosphorus. The phosphorus adsorption capacity was tested by treatment with livestock waste water treated with activated sludge (3∼30mg PO4-P/L). The sintered materials were soaked in the livestock wastewater for 10 weeks and the phosphorus concentrations in the sintered materials were measured every week. The results were that the adsorption capacity was saturated up to 0.45wt% as P2O5 by treatment for 9 weeks. Pretreatment of the removal of SS in waste water by filtering with nonwoven fabric (mesh 0.25mm) promoted the adsorption rate, that is, the adsorption capacity was saturated for 2 weeks. It is indicated the possibility that SS in waste water reduces the phosphorus adsorption by the clogging of pores of the sintered materials. The sintered materials which the phosphorus adsorption capacity was saturated, were soaked in 100-hold (v/w) of 0.8 wt% K2SO4 (pH7.0). Phosphorus was entirely eluted from the sintered materials via exchange with sulfate ion (SO42-). Then, calcium ion (Ca2+) which equal mole of phosphorus was added to elutes by addition with CaCl2, and pH of elutes was adjusted at 11.5 by addition with NaOH. By the treatments, the precipitation of calcium phosphate salt was formed. The recovered calcium phosphate mainly consists of NH4OAc-soluble phosphate. The effect of recovered calcium phosphate on the growth of spinach and Truog-phosphate in soil is similar to those of superphosphate, multiphosphate, and fused magnesium phosphate. The effect of recovered calcium phosphate on phosphate contents in plants is intermediate among those three phosphate-fertilizers. From these results, we proposed the recycling of phosphorus in soil-water system by using the sintered materials made from CRT panel glass and shell powder.
