ETE Ribeirao Bonito I - Wastewater Treatment Plant in Ribeirão Bonito, São Paulo, Brazil

ETE Ribeirao Bonito I is a wastewater treatment plant located in the municipality of Ribeirão Bonito, in the state of São Paulo, Brazil. The plant serves a population of approximately 5,600 residents, placing it in the small-to-medium agglomeration category for Brazilian sanitation infrastructure. The plant provides secondary treatment, which is the standard level required under Brazilian regulations (CONAMA 430/2011) for most inland water bodies. With a daily discharge volume of about 502 m³, the facility operates as part of the municipal sanitation system managed by the local water utility. Brazilian treatment plants of this scale typically employ activated sludge or similar biological processes to meet effluent quality standards. The treated effluent is discharged into a local watercourse within the Tietê River basin, which flows through São Paulo state and ultimately reaches the Paraná River basin. This region is part of the Atlantic Forest biome, where water quality protection is critical for maintaining aquatic biodiversity and downstream water supply for communities and agriculture.

The plant discharges into a tributary of the Tietê River, which flows through São Paulo state and joins the Paraná River system before reaching the Río de la Plata estuary. The Tietê basin is heavily urbanized and industrialized in its upper reaches, but the Ribeirão Bonito area retains agricultural and natural vegetation. Protecting water quality in this watershed supports aquatic life, including fish species endemic to the Paraná basin, and ensures safe water for downstream users.