Ji, H., Pan, S. and Han, X., 2012. Effect of wastewater discharge on Jiangsu coastal environment, China

To meet the needs of the rapid economic development in the coastal area of Qidong City in Jiangsu Province of China, a new wastewater treatment plant and a reclaimed water plant have been planned. The preliminarily treated wastewater will be discharged to the coastal area in the Yellow Sea near Dayang Port. Due to the complex tidal regime in the area, the impacts of the outfall from the treatment plant can be important for the surrounding marine environment. The present study aims to investigate the impacts of the discharge of the treated wastewater into the Yellow Sea under three operational conditions using the TELEMAC software. The computational domain covers a large coastal area (~2800 km²). TELEMAC2D is used to compute the depth-averaged currents, and the convection and diffusion of the pollutants, namely COD_Mn and Inorganic Nitrogen, which are treated as the neutral buoyancy tracers, but with temporal decay. The hydrodynamic aspects of the model are calibrated with the field measurements. The model results show a good agreement of the computed water levels and velocities compared with the field measurements. Model applications include the impact studies with the normal operational conditions of both wastewater treatment plant and reclaimed water plant, and two accidental operational conditions with increased discharges of treated and untreated wastewater. The results show that when both plants are operating under normal full capacity conditions, the treated wastewater discharged to the sea poses no threat to the water quality and marine environment under the current regulations. However, when the untreated wastewater is discharged in the sea, it will pose a significant threat to the water quality.