Simulation of the Impact Generated on a River by the Wastewater Discharge From a Latin American City

Abstract

The continued growth of cities and industrial production implies an increase in pressure on surface water bodies, which are used as a water source or as receivers of wastewater discharges. Thus, mathematical models that relate wastewater inputs to the water quality in the receiving body are often used in the control and management of water resource. Globally, various studies and technologies have been presented for the simulation of wastewater discharges with the aim of improving water quality standards, especially to improve the life quality of the inhabitants by eliminating microorganisms harmful to human health. In this regard, water quality models have proved to be a useful tool in the strategic management of water resources. The main objective of this paper is to present an impact analysis generated by the wastewater discharge from a Latin American city on Magdalena River (Colombia). This analysis is carried out using the Qual2k model and considering the minimum and maximum flows of the river under study. The findings suggested that Magdalena River tended to self-clean in those initial 5 km due to the dilution of the wastewater discharge from the treatment plant. After these 5 km, biochemical oxygen demand (BOD₅) and dissolved oxygen (DO) concentrations tended to decrease downstream toward the usual Magdalena River concentrations (15 km): 27.8 mg/l and 5.10 mg/l, respectively. This is in relation to the foretold minimum flows for Magdalena River and for a 0% pollutant removal scenario. The outcomes indicated in the 80% pollutant removal scenario that the receiving water source (Magdalena River) performed better dispersion of BOD₅ and improved DO compared to the 0% pollutant removal scenario. Concentrations of the above water quality parameters also showed less variation from the 0% removal scenario by the wastewater treatment plant. The concentrations of BOD₅ and DO in the removal scenarios of 0% and 80% allowed the Magdalena River to be classified as a source of acceptable quality according to Colombian regulations (BOD₅ < 50 mg/l and DO > 4 mg/l), possibly ensuring the preservation of flora and fauna.