Aluminum Sulfate (Alum) Supplier South Africa

What Is Aluminum Sulfate?

Aluminum sulfate (alum, Al₂(SO₄)₃) is an inorganic aluminium salt that is the globally dominant chemical coagulant for municipal drinking water treatment, potable water production, and industrial effluent clarification. Commercial aluminum sulfate is available as a hydrated solid (Al₂(SO₄)₃·~14H₂O, granular or powder, “dry alum”), or as a 49–52% liquid aluminium sulfate solution (“liquid alum”). Dry alum dissolves readily in water and hydrolyses to produce aluminium hydroxide species (Al(OH)²⁺, Al(OH)₂⁺, polynuclear Al₁₃) which carry positive charge and are highly effective at neutralising the negative electrostatic charge on suspended clay particles, silt, and natural organic matter (NOM) colloids in raw water.

Trinkwasseraufbereitung

In drinking water treatment, aluminum sulfate is added to raw water in the rapid-mix stage at controlled doses (typically 5–50 mg/L as Al₂O₃, depending on turbidity and NOM level). The alum hydrolyses to form charged aluminium hydroxide complexes that coagulate (destabilise and aggregate) suspended particles in the raw water. At higher doses or pH 6–7, sweep-floc coagulation dominates — amorphous Al(OH)₃ precipitates and enmeshes colloids in a large-surface-area floc blanket. The resulting floc particles settle under gravity in the clarifier (sedimentation basin) or are removed by DAF. The clarified water then passes through rapid sand filters before disinfection. Alum works best at pH 6–8; lime or soda ash addition adjusts pH when raw water alkalinity is low.

Industrie- und Abwasseranwendungen

In industrial water treatment, aluminum sulfate is used for process water clarification, cooling water TDS control, and paper manufacturing sizing. In the paper and pulp industry, alum is used to fix rosin sizing to pulp fibres and to control pitch deposits. In wastewater treatment, alum is a phosphate precipitant — it reacts with orthophosphate (PO₄³⁻) to form aluminium phosphate (AlPO₄), achieving effluent total phosphorus (TP) levels below 1 mg/L for discharge compliance. Terracore Chemicals supplies aluminum sulfate in granular/powder bags (25 kg) and 1 MT bags, and as liquid alum in IBC or tanker, across Southern Africa.