Determination of optimal design factors and operating conditions in a large-scale seawater reverse osmosis desalination plant

Abstract

A large-scale seawater reverse osmosis (SWRO) plant was designed with a capacity of 10 million imperial gallon per day (MIGD) and to optimize design factors and operating conditions of the plant, various evaluations were undertaken. These involved pretreatment investigations, split partial simulations, evaluation of the final water quality with respect to production capacity, and a performance comparison with other SWRO plants using the normalized specific energy consumption (SEC). As a result, the turbidity and silt density index values of the pretreatment permeates were not affected by the productivity of the plant during the operation period. Additionally, the optimum split partial ratio of the RO membranes was determined to be 4.5:5.5 which satisfied the final produced water quality and energy consumption requirements. Based on the split partial ratio, the total dissolved solids (61–280 mg/L) and boron (0.1–0.9 mg/L) concentrations of the final permeate satisfied the Korean standards at all capacities (5.7, 8.0, 10 MIGD). In particular, the total SEC of the 10 MIGD train was estimated as 3.66 kWh/m3, which is greatly lower compared to that of other SWRO plants with similar capacities. Thus, these specific performance evaluations will be useful in determining the optimal design factors and operating conditions for other large-scale SWRO plants.