The wastewater first passes through the grille and screen and then flows to the flocculation sedimentation tank. In order to make the treatment effect good, a coagulant is added to the flocculation sedimentation tank to make the treatment effect of suspended solids in the wastewater better.

Wastewater is not just sewage. All the water used in the home that goes down the drains or into the sewage collection system is wastewater. This includes water from baths, showers, sinks, dishwashers, washing machines, and toilets. Small businesses and industries often contribute large amounts of wastewater to sewage collection systems; others operate their own wastewater treatment systems.