Preliminary process selection.
work that steam will yield depends on its temperature as
preliminary site information to eliminate certain
well as the temperature to which it can be condensed.
desalination processes. A decision logic table for use
The energy consumption of both vapor compression and
with preliminary information is shown in table 4-1.
thermal distillation, as related to the total dissolved
Decisions based upon table 4-1 are to be considered
solids of feed water, is shown in figure 4-1.
preliminary only. Necessary water quality tests to
further support the recommedations made in Column E
of table 4-1 are in Column F.
Membrane energy. Historically, membrane
desalination systems use less energy than other
Brackish water disalination should be
Process selection. When initial site and raw
accomplished by membrane separation processes
water source selections have been made, use
because of the reduced energy requirement. The
preliminary water quality information with table 4-1 to
energy consumption of electrodialysis reversal can be
assist in a preliminary process selection. As more
made to follow reduced or variable salinity, while the
specific information is obtained from laboratory analyses
energy consumption of reverse osmosis is set principally
of water quality, make an initial process selection using
Again, the energy
the second decision logic table, table 4-2. After a
consumption of electrodialysis reversal and reverse
treatability investigation has been completed, select the
osmosis as a function of the total dissolved solids
final desalination process. A final decision logic table,
content of the feed water is shown in figure 4-1. As
table 4-3, assists in the final process selection. The use
of the decision logic table sequence will only provide
consumption may be reduced.
generalized assistance in process selection; additional
economic, engineering, and environmental studies may
Waste disposal. Waste disposal may influence
process selection. Since brine disposal costs can be an
important part of process economics, brine disposal
alternatives must be explored while water quality
analyses are being performed. For further information,
refer to Chapter 10 on waste disposal.