The objective of the proposed research is to develop a computer model of both the unit processes and overall treatment system. Model development will be supported by laboratory research addressing (1) the ability to concentrate divalent ions from high salinity flue gas desulfurization (FGD) wastewater of varying chemistry, and (2) the ability to precipitate gypsum and magnesium hydroxide from concentrated ion-exchange brines. The model will calculate process performance, mass and liquid flow rates, and heat requirements; it will be used to evaluate the technical feasibility of a full-scale treatment process. The technology developed in this study will be relevant to utilities considering zero liquid discharge of FGD wastewaters. The project objectives will be achieved through a combined laboratory and modeling effort to develop a novel treatment process for FGD wastewater. Lab studies will be conducted to investigate divalent ion removal and precipitation of gypsum and magnesium hydroxide from brine solutions. The process model will enable performance to be predicted and optimized by calculating flow, mass, and energy balances.