Smart water grid is a water network with communication to save water and energy using various water resources. In smart water grid, water product from the various sources can be blended to be supplied to end-users. The product water blending was reported by literatures while feed water blending has been rarely reported so far. In this work, a commercial reverse osmosis (RO) system design software provided by a membrane manufacturer was used to elucidate the effect of feed water blending on the performance of seawater reverse osmosis (SWRO) plant. Fresh water from exisiting water resource was assumed to be blended to seawater to decrease salt concentration of the RO feed water. The feed water blending can simplify the RO system from double to single pass and decrease seawater intake amount, the unit prices of the RO system components including high pressure pump, and operation risk. Due to the increase in RO plant capacity with the feed water blending, however, the RO membrane area and total power consumption increase at higher water blending rates. Therefore, a specific benefit-cost analysis should be carried out to apply the feed water blending to SWRO plants.

In this study, the evaluation criteria of performance and applicability is developed to rank the combinatorial technologies for SWG (Smart Water Grid) system using AHP (Analytic Hierarchy Process) method. Security, safety, solution, suitability and sustainability which are goals of SWG technology, are used as upper level hierarchy elements. And three detailed elements for each upper level hierarchy are adopted as the lower level hierarchy. The weighted value which represents the importance of each element, could be determined through questionnaires accomplished by groups of specialists who are engaged in relevant waster industry and research area. To assess the accuracy of the evaluation criteria developed in this study, a simulation on four decision alternatives for smart water grid was carried out as an evaluation. Consequently which showed 90 % of accuracy.