Adelaide Desalination Plant Process Design: Energy Use Optimization

Abstract

The 300-ML/day Adelaide (Southern Australia) Desalination Plant (ADP) exemplifies efficient energy use throughout its pretreatment, reverse osmosis (RO), posttreatment, storage, and waste management systems. Its location at Port Stanvac—32 km southwest of Adelaide and 52 m above sea level—posed some design challenges. The RO unit was engineered using a novel double pass, a particularly energy-efficient arrangement because the unit uses a blind split between the third and fourth elements in the first pass (eight elements per pressure vessel). Pressure-exchanger energy-recovery devices are used for high-pressure saline concentrate, and Francis turbines are used to recover energy from depressurized saline concentrate prior to discharge to the outfall. Recirculation of second-pass concentrate streams and recycling of clarified wash-water supernatant also minimize overall energy consumption. RO system recovery (48.3 percent) is high by industry standards, reflecting the importance of site elevation to optimize process design. This article describes solutions to site-specific challenges, compares ADP's RO energy use with typical conventional design, and presents strategies to maximize use of seawater pumped to the process plant.