ETE Santa Paula Wastewater Treatment Plant, Jacareí, São Paulo

ETE Santa Paula is a municipal wastewater treatment plant located in the Residencial Santa Paula neighborhood of Jacareí, in the state of São Paulo, Brazil. The plant serves a population of approximately 8,347 residents, making it a small-scale facility within the densely populated Vale do Paraíba region. The plant provides secondary treatment, which is the standard level required under Brazilian regulations (CONAMA resolutions) for most inland water bodies. The plant discharges an average of 730.48 m³/day of treated effluent. As a secondary treatment facility, it removes organic matter and suspended solids, meeting typical permit limits for biochemical oxygen demand and total suspended solids. The treated effluent from ETE Santa Paula ultimately drains into the Paraíba do Sul River basin, a major watercourse in southeastern Brazil. The river flows through the Paraíba Valley and empties into the Atlantic Ocean near Campos dos Goytacazes. The watershed supports diverse aquatic life and provides water for agriculture, industry, and drinking water for millions of people downstream.

The plant's discharge enters the Paraíba do Sul River basin, which flows through the Atlantic Forest biome and is a critical water source for the Rio de Janeiro metropolitan area. The river supports a variety of fish species and is an important migratory corridor. Downstream, the river reaches the Atlantic Ocean, contributing to coastal ecosystems. The region's tropical climate and seasonal rainfall patterns influence the river's flow and dilution capacity.