Assessing the capacity of the water source to receive wastewater for issuing discharge of wastewater permits

Abstract

The environmental carrying capacity refers to the maximum load that an environment can sustain while still meeting quality requirements for specified uses within a designated research area. In this study, we applied the MIKE 21 model with two modules: Hydrodynamic (HD) and Ecological (Ecolab). The purpose was to assess the water’s capacity to receive wastewater and predict trends in water quality changes resulting from development activities in the Vu Gia-Thu Bon River estuary region. After calibrating and validating the MIKE 21 model in 2005 and 2009, the results indicated that the organic matter decay coefficient kd = 0,11 and the longitudinal dispersion coefficient Ex ranges from 50 to 150 m²/s for each river segment, facilitating the simulation of water quality in the Vu Gia-Thu Bon estuary. The simulation results of the numerical model indicate a current increase in pollutant concentration in the Vu Gia-Thu Bon estuary area. However, this increase is mild and does not significantly impact environmental pollution, as most measured parameters remain within permissible limits. Nonetheless, it is crucial to implement appropriate wastewater management and treatment plans, including contingency measures, to prevent the direct discharge of pollutants into the river basin. Keywords: MIKE 21 model, Vu Gia-Thu Bon river, wastewater, Da Nang