Advances in Brine Disposal and Dispersion in the Coastal Ecosystem from Desalination Plants

Abstract

The unpredictable water pollution incident of the coastal environment is an important part of the emergency work. Based on the Navier stokes equation set, a 2-D pollutant dispersion model is built for the selected 2D domain in the coastal ecosystem. It calibrates key parameters with the various characteristics, rapidly and effectively achieves the forecasting of pollutant dispersion using implicit finite difference scheme in this paper. The model can maximize the information obtained from the available data and adapt to the fast evolution of the coastal bed as well as other external boundary changes. The experimental results show that the model provides a strong support for relevant decision makers with high usability and reliability. Reverse Osmosis (RO) Plant draws saline water from sea inlet and converts it into potable water and discharges brine water at outfall as effluent. The paper discusses mathematical model studies for dispersion of brine water with salinity of 63 ppt from a Reverse Osmosis (RO) plant into coastal waters at north Chennai. Studies were carried out to observe the brine water plume behavior in the vicinity of coastal area with different outfall locations. Initially the outfall was located at 1,000 m from shore and studied, subsequently studies were repeated for 750 and 500 m locations. The outfall plume dispersed in and around the outfall. The development of plume at each outfall location for different ambient conditions was studied. The possibility of effluent reaching the shore was also studied. The studies were carried out considering different orientation of port, and the dilution aspects of multiport and single port diffusers. The design discharge criteria and suitable outfall locations were determined from the studies. The study indicated that higher velocity and larger port diameter helps in enhancing dispersion rate and hence adverse effects on marine ecosystem can be minimized. Finally the outfall was located at 750 m from shoreline and the same was commissioned in the year 2007. The field measurements were carried out for salinity concentration at different distances from the outfall (50–500 m in the interval of 50 m). The simulated salinity plume compared with field measurement. It could be seen that the model results with field measurement were considered to be satisfactory.