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عمران::
تاسیسات نمک زدایی
The environmental concerns associated with the discharge from any desalination facility revolve around the brine that is produced as a byproduct of the desalination process and its poten- tial effects on receiving water organisms� The hypersaline discharge tends to be of a higher density than the receiving water and can, therefore, sink to the bottom and negatively impact benthic and demersal organisms in the vicinity of the discharge� Diluting the brine to reduce its salinity prior to discharge can minimize negative effects� If this is accomplished by increasing the intake vol- ume, then the reduced discharge effects may be offset by the increased impacts associated with the elevated intake flowrate (e�g�, increased impingement and entrainment, habitat loss due to the need for an enlarged intake structure)�
The characteristics of the source water body used by the intake can have a large impact on the design and operation of a desalination facility as it influences both performance and environ- mental impacts� Physical factors such as temperature, salinity, and turbidity may be relatively stable in one location but fluctuate widely on a seasonal or even daily basis at another spot within the same water body� Ship traffic, storm water, river flows, currents, waves, tides, and shoreline characteristics at different locales determine which intake technology will perform well and which will be unsuitable from place-to-place�
Using the discharge water from an existing coastal power plant (which uses seawater for cooling) as the feed water for a desalination facility eliminates con- struction impacts and typically will not introduce any new operational impacts� Shunting water through a desalination facility does nothing to increase the impingement and entrainment already associated with the operating power plant's circulating water system and routing the membrane concentrate into the existing discharge pipe helps to dilute and disperse it� Environmental concerns are typically associated with the impact on local biota of potentially for extending the operating life of the intake after the power plant has been decommissioned�
Seawater intake wells have a relatively small yield (≤3�6 mgd or 14,000 m3/d) so that desalination facilities with large capacities would require many wells� Large stretches of shoreline could therefore be disrupted by the construction of large-capacity systems� HDD and slant well structures and access roads can be built further from the water's edge, minimizing both loss of near coast habitat and aesthetic impact to the beach zone�
Due to the expanse of shoreline that needs to be disturbed and excavated, the impact of the installation of an infiltration gallery would be significant� This massive excavation work would yield large amounts of beach sand excavation debris, a portion of which (10 to 20 percent) would have to be transported and disposed of off-site� For some locations, this may be a challenging task� The extensive beach excavation required has the potential to impact shore birds, marine mammals, and intertidal organisms in the area of construction� Construction activities would cause temporary disruptions to tourists and public use of the beach� The pipeline network necessary to link the wells with the desalination facility would require extensive trenching and subsequent burial of the system�
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