Evaluation of kinetic and statistical models for predicting breakthrough curves of phosphate removal using dolochar-packed columns

The sustainability in utilizing dolochar packed columns under dynamic conditions for phosphate removal from aqueous solutions, has been carried out in this study. The assessment of efficacy of the bed under varying experimental conditions of bed depth, flow rate and influent phosphate concentration revealed that, an increase in bed depth and initial phosphate concentration or a decrease in flow rate resulted in increased breakthrough and exhaustion time. Thomas, modified dose response (MDR) and Clark models were applied to simulate the experimental breakthrough curves following nonlinear regression analysis. Also bed depth service time (BDST) model was engaged to scale up the adsorption process by means of linear regression approach. All the models with a very high coefficient of correlation (R-2 > 0.93) predicted the breakthrough curves equally well. Good consistency was observed among experimental bed adsorption capacity (8.56 mg g(-1)) and those predicted by Thomas (9.21 mg g(-1)) and MDR models (8.81 mg g(-1)). Statistical modeling proposed quadratic models for breakthrough and exhaustion time, with R-2 values of 0.99 in both the cases. Soil column analytical test confirms slow release of phosphate from spent dolochar. The results confirm the sustainable application of dolochar packed columns for phosphate abatement in large scale accompanied by the utilization of spent dolochar as a source of phosphate.