PHOSPHATE REMOVAL BY ADSORPTION

Phosphate removal efficiencies of 13 natural pumice rock samples obtai ned from different regions of Turkey were investigated. Samples with h igh CaO content had high phosphate adsorption capacity. It is conclude d that pumice is an effective adsorbent for phosphate if its CaO conte nt is high. The adsorption capacity of a pumice powder sample was calc ulated from the area under the curve of the plot phosphate concentrati on vs volume of the effluent as 0.95 mg PO4-3 g(-1) pumice powder. Var iation of pH, conductivity(S) and redox potential (mV) was also measur ed during the column experiment. Langmuir and Freundlich adsorption is otherm constants and correlation coefficients were calculated and comp ared. It was concluded that the adsorption data of phosphate onto pumi ce powder fitted to the Freundlich adsorption isotherm more than the L angmuir model. Specific surface areas of the pumice powder were calcul ated at pH 3, 5, 7 and 9. The compounds present in actual waste water have no significant effect on the removal of phosphate. Pumice powder can be regenerated by dilute NaOH and reused.