Encyclopedia of Environmental Science and Engineering, Volume I and II

WATER TREATMENT 1321

FEED

REJECT

PERMEATE

MORE

CONCENTRATED

BRINE

RETURN ENDS

OF FIBERS PRESSURE

TUBE-STEEL

THOUSANDS OF “HAIR-PIN”

HOLLOW FIBERS

EPOXY POTTING FILLED

SPACE AROUND ENDS

`OF HOLLOW FIBERS

MAGNIFIED SECTION OF ENDS

OF HOLLOW FIBERS (BOTH

ENDS)

FRESH WATER

PRODUCT

SALINE WATER

FIGURE 17

Saline

Water

Feed

+

+

+

+

Selectivelon –

Membrane

Brine Fresh

Water

Brine

Electrodialysis

FIGURE 16

about further cooling. Close to freezing ice crystals will

form with a brine coating, and washing of these crystals will

yield fresh water from the washed ice. Small plant appli-

cation appears to be feasible at the moment. Considerable

development work on this was done by the Technion Institute

in Israel.

A Secondary Refrigerant Process This involves the use of

a second hydrocarbon refrigerant, such as butane, that will

not mix with water. A great deal of care must be exercised

S.W.

14

IN

18

HEAT EX.

10

19

11

24 28

13 16

VAPORIZATION-COOLING

STEAM

GENERATOR

SOLUTION

HEAT EX.

27 VENT

ABSORBER

CONC

WATER

SEA

OUT

FRESH WATER

OUT

FIGURE 15 Vapor reheat with vapor

recompression by absorption (from

US Patent 3,288,686). Vapor reheat

MSF, vapors formed in low pressure

stage pass to Absorber, 27, and are ab-

sorbed in the hydrophilic liquid from

solution heat exchanger, which cycles

through heat exchanger to evaporator

or generator, 28, for concentration at

higher pressure. Vapors leave at higher

pressure to half-stage, 19, to supply

prime heat to evaporator.

process which offers considerable promise for the desalina-

tion of brackish waters.

The Vacuum Freezing Process Cooled saline water passes

into a low pressure chamber where flash evaporation brings

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