Evaluating Al-based coagulants for drinking water facilities using Jar test and CCD/RSM analysis

Abstract

This study evaluated Al-based coagulants for turbidity removal optimization in drinking water facility using Jar test and CCD/RSM analysis. The wide use of aluminum salts requires researching improved Al-based coagulants to reduce the treatment dosage. Eight polyaluminum chloride coagulants (PACl), i.e., Hyperlon 4064-PACl 2, Hyperlon 4393, 1757 X1, 1757 XL8- PACl 1, Ultrafloc 1406, Ultrafloc 3759, AlcoPAC 6, and AlcoPAC 1010 were first compared using a series of jar tests to determine the best candidate in removing the settled and filtered turbidity in water. The results showed that all PACls performed better than alum in removing water turbidity, but Hyperlon 4064 was the best. Then, the central composite design/response surface methodology (CCD/RSM) analysis was applied to Hyperlon 4064 to optimize dosage and pH to achieve the lowest final settled and filtered turbidity in the treated water, which were 21.7 mg/L, 7.53 and 27.95 mg/L, 7.91, respectively. Two quadratic models were generated by the CCD/RSM analysis with high correlations between the actual and predicted responses (R 2 = 0.9881 and 0.9809 for final settled turbidity and final filtered turbidity). The results from this study can provide useful information to the operating water treatment plants that use Al-based coagulants to remove turbidity in water.