ETE Bacia Leste Wastewater Treatment Plant, Caçapava, São Paulo

ETE Bacia Leste is a municipal wastewater treatment plant located in Caçapava, within the Metropolitan Region of Vale do Paraíba e Litoral Norte, São Paulo, Brazil. The plant serves a population of around 24,086 residents, classifying it as a medium-sized agglomeration under Brazilian sanitation standards. As a plant in Brazil, ETE Bacia Leste is subject to CONAMA Resolution 430/2011 and state-level environmental regulations, which set effluent discharge standards. For agglomerations of this scale, secondary treatment is typically required to reduce organic load and suspended solids before discharge. It operates within the framework of Brazil's national sanitation plan (Plansab) and water resource management policies. The plant discharges treated wastewater into the Paraíba do Sul River basin, a major watercourse in southeastern Brazil. The Paraíba do Sul River flows through the states of São Paulo, Rio de Janeiro, and Minas Gerais, ultimately reaching the Atlantic Ocean near Campos dos Goytacazes. The river supports diverse aquatic life and provides water for millions of people, making effective treatment crucial for downstream communities and ecosystems.

The Paraíba do Sul River basin is a vital water resource for southeastern Brazil, supplying drinking water to over 14 million people and supporting agriculture and industry. The river flows through the Atlantic Forest biome, a biodiversity hotspot, and its estuary hosts mangroves and fish nurseries. ETE Bacia Leste's treated effluent contributes to the river's flow, and proper treatment helps protect downstream water quality and aquatic habitats.