Assessing desalination pretreatment conditions towards pilot scale up using Box‐Behnken experimental design

The purpose of this study is to optimize the operating conditions in batch mode using Box-Behnken Design (BBD), for the coagulation-flocculation line sizing prior the sand filter in the pilot scale. Three coagulants were employed to achieve a high turbidity removal with a low concentration of residual metals. The results showed that the best turbidity removal was obtained with FeCl3. Using BBD (15 experiments), the optimal parameters were: coagulant dose = 5.5 mg FeCl3/L, slow stirring time = 33 min and slow stirring velocity = 45 rpm, in these conditions, the turbidity removal reached 94.89% and the residual iron concentration was 0.449 mg/L. Regarding the model fit, the obtained R-2 values were 99.67% for turbidity removal and 99.47% for residual iron concentration. The optimum conditions obtained from this study could be scaled up and applied to desalination plants. BBD approach is of great interest because it allows the prediction of the response value without performing experiments.