DOI: https://doi.org/10.55373/mjchem.v28i5.86

Keywords: Tropical peat water, PAC-chitosan system, turbidity removal, organic removal, solvent effect

Abstract

Tropical peat water is difficult to clarify because of its intense colour, colloidal content, and high concentration of oxidisable organic matter. This study evaluated polyaluminium chloride (PAC) and chitosan as single coagulants and as a combined coagulation system, with particular attention to PAC and chitosan dosage and the acid medium used for chitosan preparation. Jar tests were conducted using natural peat water. PAC and chitosan used individually produced their highest observed turbidity removals at 20 mg L⁻¹, reaching 96.93% and 97.46%, respectively. In the broad PAC–chitosan dose evaluation, 5 mg L⁻¹ PAC combined with 0.2 mg L⁻¹ chitosan produced 97.8% turbidity removal, whereas higher PAC dosages reduced treatment performance. In the low-dose solvent comparison, chitosan dissolved in 2% (v/v) acetic acid generally produced higher and more consistent turbidity removal than chitosan dissolved in 2% (v/v) HCl. The highest observed removals were 99.21% for the acetic-acid system at 1 mg L⁻¹ PAC and 98.01% for the HCl system at 5 mg L⁻¹ PAC. Oxidisable organic-matter removal was lower than turbidity removal, with a maximum of 33.23% at 5 mg L⁻¹ PAC and 0.2 mg L⁻¹ chitosan. These findings indicate that low PAC dosages combined with chitosan prepared in acetic acid provided the most favourable turbidity-removal performance among the tested conditions, while oxidisable organic matter remained more difficult to remove.