Outcomes And Future Considerations

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The pilot, bench-scale, and desktop studies undertaken for the Las Vegas Valley indicate that desalination, while technically feasible, is costly. The initial estimates were, at best, $4.73 kgaP1 with substantial water loss involved. The follow-up study indicated that an optimized ZLD system could be set in operation at a cost of $4.51 kgaP1 with improved water recovery and reduced energy consumption. However, these costs still compare unfavorably to production costs of less than $1.23 kgaP1 for water from other sources. As such, one must carefully weigh the costs and benefits of implementing a desalination system, especially in inland settings where high recovery and adequate means for brine disposal are paramount to success.

Table 6 Summary of energy requirements (kWh/kgal concentrate recovered)

Benchmark ZLD process

Evaluated ZLD process

Beverly Hills, CA

12.1

64.9

SNWA, NV

20.6

68.6

Phoenix, AZ

12.0

74.2

Scottsdale, AZ

21.2

75.9

SAWS, TX

16.9

75.3

In a critical discussion of the interrelationship between increasing supply and rising demand, and the distinction between true needs and perceived needs, von Medeazza cautions against unchecked expansion into desalination and production of water simply because the resources exist to continue society's water-intensive lifestyles [17]. Such considerations must be included in future discussion of the value of tapping into unexploited water resources. Energy requirements, environmental impacts, monetary costs, and societal benefits must all be weighed in the final decision about using desalination for drinking water production at inland sites. If desalination of Las Vegas Valley shallow groundwater is to be a realistic option, a system must be designed that accounts for true population needs, local conditions, and takes advantage of as many factors as possible to optimize energy consumption and maximize profit potential. As a general rule, such an approach will be necessary anywhere - each facility will need to be tailored to match site-specific conditions.

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