Augmenting ocean water desalination with potable reuse: Concept feasibility in terms of cost and environmental impacts

This study provides a conceptual analysis of augmenting ocean water desalination with potable reuse to provide a new water supply. Ocean raw water augmentation, ocean treated water augmentation, and integrated facility approaches were compared to the expansion of a conventional ocean water desalination facility. Operating and capital expenditures were analyzed, and environmental and construction impacts were also considered. The costs of water production for the three augmentation approaches were within 10% of that for the ocean water desalination facility. However, a 12% lower cost was deduced when the marginal cost of the potable reuse supply component was compared to the ocean water desalination supply component. The costs of water production for the augmentation approaches were also within the range of costs found in the literature for potable reuse and ocean water desalination supplies. The augmentation approaches reduce intake and pretreatment requirements for ocean water. Salinity levels for the combined discharges to the ocean outfall were found to be (∼25%) higher for the augmentation approaches than for the ocean water desalination facility; however, discharge flowrates were ∼60% lower. Lower flowrates of more concentrated discharge could have implications for future scenarios of zero liquid discharge. Extending to other regions of the world with limited natural water resources and existing ocean water (or seawater) desalination facilities, augmentation should be considered to increase potable water supply using wastewater that would typically be disposed to the ocean/sea.