Aluminum sulfate, commonly known as alum, is an inorganic salt widely used as a coagulant in water treatment processes. With the chemical formula Al₂(SO₄)₃, it appears as a white crystalline solid or powder that dissolves easily in water. When added to water, aluminum sulfate hydrolyzes to form positively charged aluminum hydroxide complexes, which neutralize the negative charges on suspended particles. This leads to coagulation and the formation of larger aggregates, or flocs, which can be removed through sedimentation and filtration. It is one of the most cost-effective and efficient chemicals for clarifying drinking water, removing turbidity, organic matter, and certain pathogens. Beyond water treatment, aluminum sulfate is also used in paper manufacturing for sizing, in the textile industry for dye fixation, and in wastewater treatment facilities. Typically applied in dosages of 10–50 mg/L, its efficiency depends on water chemistry, pH, and temperature. Although generally safe when used correctly, it is mildly corrosive and requires careful handling to avoid skin and eye irritation. Stored in dry, cool environments, it remains stable for extended periods. Due to its wide availability, affordability, and proven performance, aluminum sulfate remains one of the most essential coagulants in industrial and municipal applications worldwide.