Comparing the water treatment ability of polyaluminum chloride and ferric sulfate

Abstract

This thesis compares the coagulation performance of polyaluminum chloride (PAC) and ferric sulfate for removing key water-quality pollutants: COD, BOD, turbidity, and UV254 —through a literature-based synthesis with a standardized comparison of operating pH, dose, and “pollutant removed per mg coagulant.” PAC and ferric achieved broadly similar COD removal at near-neutral pH, while ferric sometimes surpassed PAC under acidic conditions, indicating stronger pH sensitivity for ferric and steadier COD performance for PAC across typical operating ranges. For BOD, both met common treatment targets; PAC reached higher peak removals, whereas ferric delivered more uniform outcomes under comparable conditions.

PAC consistently outperformed ferric on turbidity, achieving ≥90% removal across acidic–alkaline conditions with practical doses; ferric also clarified effec-tively but often required higher doses to match results.Finally, PAC showed a clear advantage for UV254 (DOM) reduction, routinely approaching ~85–90% under neutral conditions, while ferric typically achieved much lower removals except in unusually polluted matrices.

Overall, PAC is recommended when stable performance, strong turbidity and UV254 reduction, and chemical economy are priorities; ferric sulfate remains a strong option where acidic operation is feasible or when consistent COD/BOD control at neutral pH is the primary aim.