Phosphate removal from wastewater using fly ash with microfiltration

ABSTRACT Master Thesis PHOSPHATE REMOVAL FROM WASTEWATER USING FLY ASH WITH MICROFILTRATION Mevra YALVAÇ CAN Atatürk University Graduate School of Natural and Applied Sciences Environmental Engineering Department Supervisor : Asst. Prof. Dr. Ergün YILDIZ Removal of phosphate ions from aqueous solution by means of fly ash was investigated in a cross flow microfiltration system consisting membranes with the pore size of 0.45 um. Firstly batch experiments were conducted to determine phosphate ions removal capacity of fly ash. The effect of phosphate concentration, initial solution pH and fly ash dosage on the phosphate removal was studied. Optimum initial pH level was between 5- 6. When fly ash of 2 and 4 g/L dosage was used for 25 and 100 mg/L phosphate concentration, respectively, about 100 % removal was obtained. In membrane filtration, phosphate ions treated with fly ash were seperated from water with crossflow microfiltration technique. The effects of fly ash dosage, phosphate concentration, transmembrane pressure drop (AP) and membrane type on the membrane fluxes (J) and rejections (R) were investigated. It was seen that fluxes increased with increasing the dosage of fly ash and the concentration of phosphate in the feed solution. Furthermore, it was also found that better results were obtained with cellulose nitrate membranes than cellulose acetate membranes for J and R. Specific cake resistances (a) of cake layer on the membrane were calculated by classic cake filtration equation. It was shown that a values decreased with increasing dosage of fly ash and concentration of phosphate which led an increase at flux. 2002, 94 pages Keywords : Membrane filtration, Microfiltration, Phosphate removal, Fly ash, Flux decline u