Assessment of The Self-Purifying Capacity of The Low Course of The River Pimenta, São Luís – MA

Objectives: To investigate the self-purification capacity of the Pimenta River in São Luís, Maranhão, in response to contamination by organic pollutants. Theoretical Framework: Contamination of water bodies harms human health and ecosystems. Self-purification is a natural process that helps rebalance water after the introduction of pollutants, and is essential for assessing river recovery. Method: The Streeter-Phelps model was used to assess dissolved oxygen (DO) and biochemical oxygen demand (BOD) levels in the river, performed in the laboratory, in addition to flow measurements. Results and Discussion: The results showed that the Pimenta River has limitations in its self-purification capacity, with BOD and DO values ​​outside the legal parameters. This indicates that effluent discharges compromise water quality and affect the ecosystem. Research Implications: The research highlights the need to improve water resource management and implement public policies to protect the local ecosystem and ensure water quality. Originality/Value: The study offers an original analysis of the self-purification capacity of the Pimenta River, contributing to environmental management and public water protection policies in the region.