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There are two power generation and seawater desalination plants currently operated at Barka, Oman: Barka I was commissioned in 2003, and Barka II in 2009. The cooling water from the power generation plants are mixed with reject brine (and other effluents) from desalination plants and are discharged through the same marine outfall systems. Therefore, during 2009, the brine discharge plumes changed from the previously positively buoyant from Barka I plant to a newly negatively buoyant from the combined Barka I and II plants. Consequently, instead of rising to the sea-surface, the new brine plume will now tend to sink and stay at the seabed. CORMIX simulations were carried out for two scenarios that represent the previous heated brine discharges and the new concentrated brine discharges from the Barka plants. Due to uncertainty in the input data, further simulations were carried out using salinity as a measure of the plume concentration for single port and multiport, and by varying the ambient current velocity, the effluent discharge density and flow rate. The results show that the water quality standards in the Omani coastal marine environment within the regulatory mixing zone at a 150 m radius from the discharge point have been met for both scenarios. However, the potential benthic impact due to the attachment of the new brine plume at the seabed should be monitored and investigated further. [ABSTRACT FROM AUTHOR]

As desalination develops, the impacts of brine ocean disposal rise increasing concerns. Here we present a screening of the hurdles to brine disposal through pressurized submerged outfalls in the broader Mediterranean region. Using first-tier dilution models, we analyze how different environmental quality standards reflect in terms of initial outfall velocity. We show that achieving moderate dilution is usually not problematic, while higher environmental quality standards would often require excessively high initial velocities. Although this may not be so overwhelming a problem as to undermine the feasibility of brine discharge, it indicates possible hurdles to arise in the permitting of a project. We also show that increasing water recovery (i.e. having more concentrated brine) reduces jet extents, hence allows disposal in shallower waters, with smaller pipelines, causing an appreciable reduction of costs, while also slightly reducing pumping energy demand (which is rather small anyway in comparison with the overall energy demand of the desalination process). This makes recovery of water from the brine a potentially interesting management option, to be appraised against the costs of increasing recovery, and the difficulties arising from the higher dilution required at the outfall. • Brine disposal may be a significant hurdle for the permitting of desalination plants in the Mediterranean. • A large percentage of the potentially served population may require complex outfall design. • When dilution requirements are met , concentrating the brine beyond typical recovery would reduce the distance of disposal from the coast, and cut on disposal costs. • Further brine concentration should be appraised in relationship with the costs of increasing recovery. [ABSTRACT FROM AUTHOR]

While we increasingly turn to desalination as a secure water supply, it is still perceived as an expensive and environmentally damaging solution, affordable only for affluent societies. In this contribution, we recast desalination from one of a last resort to a far-reaching, climate change mitigating, water security solution. First, we argue that the benefits of desalination go beyond the single-use value of the water produced. If coupled with water reuse for irrigation, desalination reduces groundwater abstraction and augments the water cycle. As such, it may support both adaptation to, and mitigation of climate change impacts by deploying plentiful water for human use, with all the benefits that entails, while helping preserve and restore ecosystems. Second, we counter two arguments commonly raised against desalination, namely its environmental impact and high cost. The environmental impact can be fully controlled so as not to pose long-term threats, if driven by renewable energy. Desalination may then have a zero carbon footprint. Moreover, appropriately designed outfalls make the disposal of brine at sea compatible with marine ecosystems.. Recovery of energy, minerals and more water from brine reject (particularly in the form of vapour for cooling to enable more crops and vegetation to grow), while possible, is often hardly economically justified. However, resource recovery may become more attractive in the future, and help reduce the brine volumes to dispose of. When fresh water becomes scarce, its cost tends to go up, making desalination increasingly economic. Moreover, desalination can have virtually no environmental costs. Considering the environmental costs of over-abstraction of freshwater, desalination tilts the balance in its favour. • Here we recast desalination as a "win-win solution" to restore the water cycle. • Desalination to become mainstream as societies understand its broader benefits. • Coupling with water reuse maximizes socioeconomic/ecological return on investments. [ABSTRACT FROM AUTHOR]