Industrial effluents are liquid wastes generated from manufacturing, processing, and service industries, often containing toxic chemicals, heavy metals, organic pollutants, suspended solids, oils, acids, alkalis, and thermal discharges. If released untreated into water bodies or land, these effluents can cause severe environmental degradation, public health hazards, and ecological imbalances, turning industrial activity into a major source of man-made disasters. Effective treatment of industrial effluents is therefore essential not only for pollution control but also for disaster risk reduction and sustainable industrial development. The treatment of industrial effluents aims to remove contaminants to acceptable levels before discharge or reuse. The treatment process typically involves a combination of physical, chemical, and biological methods selected according to the type of industry and characteristics of wastewater. Industries such as textiles, pharmaceuticals, petrochemicals, food processing, mining, tanneries, and paper mills generate effluents with distinct compositions, making customized treatment systems necessary. The first stage of treatment is preliminary or primary treatment, which focuses on removing large solids and suspended matter. Screening is used to trap large debris, plastics, and coarse particles. Grit chambers remove sand and heavy inorganic materials that could damage equipment. Sedimentation tanks allow suspended particles to settle by gravity, forming sludge at the bottom while lighter materials like oils and grease float and are skimmed off. This stage reduces the