Sewage treatment involves several key stages to effectively purify wastewater. The primary processes include: Preliminary Treatment: Removal of large debris and grit. Primary Treatment: Physical separation of solids and liquids through sedimentation. Secondary Treatment: Biological processes to break down organic matter. Tertiary Treatment: Advanced processes to further polish the effluent, often involving filtration and disinfection. Each stage plays a crucial role in producing treated effluent that meets stringent environmental standards, ensuring its safe discharge back into the environment.