The aim of the present study was to evaluate the performance of two pre-hydrolyzed aluminum coagulants (PAX-XL6 and PAX-XL8) in comparison with aluminum sulfate (alum) for surface water clarification. Jar-test experiments were conducted with coagulant doses ranging from 0 to 15 mg Al/L to determine the optimal dose. Results demonstrated that both the coagulant type and dosage strongly influenced clarification performance. The pre-hydrolyzed coagulants achieved the bests results, with maximum color removal efficiencies of 91.8% and turbidity removals of 89.3% (PAX-XL6) and 84.6% (PAX-XL8) at an optimal coagulant dose of 4 mg Al/L. In contrast, alum showed the lowest clarification performance, achieving maximum color removal of 87.5% and turbidity removal of 80.3%. At 4 mg Al/L, the pre-hydrolyzed coagulants met WHO drinking water guidelines for color and turbidity, whereas alum failed to meet color standard. Beyond 8 mg Al/L, all coagulants exhibited a decrease in clarification efficiency due to colloid restabilization. Regarding water chemistry, PAX-XL6 and PAX-XL8 induced only moderate reductions in pH and alkalinity, whereas alum caused significant acidification and a marked decrease in alkalinity. None of the coagulants affected water hardness. Overall, the pre-hydrolyzed coagulants demonstrated superior clarification performance and reduced chemical impact, confirming their potential as efficient and sustainable alternatives to alum for surface water treatment.
Seyhi et al. (Wed,) studied this question.