PAC vs PACS: How Basicity Affects Coagulation Performance
Al₂O₃ percentage alone is not enough to select between PAC and PACS. Basicity, sulfate content, aluminum speciation, raw-water pH and load together determine coagulation behavior.
How are PAC and PACS different?
PAC is a family of polyaluminum chloride coagulants. PACS additionally contains sulfate; sulfate can influence polymeric structure and floc-formation behavior.
What does basicity mean?
Basicity describes the degree of pre-hydrolysis/neutralization during manufacture and can change the distribution of aluminum species. It is not a sufficient selection criterion by itself.
Is higher basicity always better?
No. Research shows that performance can depend on raw-water sulfate, pH, hydrolysis kinetics and other water characteristics.
What should be compared in a jar test?
Compare raw-water pH/alkalinity/temperature, turbidity, organic load, current coagulant/dose and target treated-water quality. PACS should be verified with the actual water.