ETE PIRAJA Wastewater Treatment Plant, Teresina, Piauí, Brazil

ETE PIRAJA is a wastewater treatment plant located in the Pirajá neighborhood of Teresina, the capital city of Piauí state in northeastern Brazil. The plant serves an estimated population of 80,325 people, placing it in the medium agglomeration category for Brazilian wastewater infrastructure. Brazil's wastewater treatment standards are governed by national regulations, including CONAMA resolutions and state-level environmental agencies. For plants of this scale, secondary treatment is typically required to meet discharge standards. It operates within the regulatory framework that mandates appropriate treatment for urban wastewater. The plant discharges treated effluent into local water bodies that drain into the Parnaíba River basin, one of the major river systems in northeastern Brazil. The Parnaíba River flows northward to the Atlantic Ocean, supporting diverse aquatic ecosystems and providing water for agriculture and communities along its course.

The plant's treated effluent enters the Parnaíba River basin, which flows into the Atlantic Ocean via the Parnaíba Delta, an ecologically sensitive area with mangroves and wetlands. The river supports diverse aquatic life and is important for local fisheries and biodiversity. Proper treatment helps protect downstream water quality and ecosystem health.