B. Rout, T.K. Panda and B.B. Kar
Abstract
Phosphate immobilization in synthetic waste water is done using fly ash which contains 6.78% of calcium ions. The maximum dephosphorization capacity of fly ash was calculated to be 0.84 mg per gram of fly ash. By using Freundlich adsorption isotherm, the sorption is considered to be the combined effect of adsorption as well as precipitation or a multilayered adsorption process. When the experiment was done at the same condition for raw waste water collected from dairy plant revealed that less amount of phosphate was removed by the same fly ash. Langmuir adsorption isotherm was adopted to calculate the maximum adsorption capacity of the adsorbent. Considering the process to be a monolayer adsorption process. The maximum phosphate removal capacity for fly ash in case of dairy effluent was found to be 0.312 mg/g. Due to the presence of sulphate, bicarbonate and chloride ions the rate of phosphate precipitation was affected hence the phosphate removal was considered as a purely adsorption process. Two different adsorption isotherms were accepted for the two phosphate solution by comparing the regression constant values.