In certain locations following a drought it 
might take as much as seven years to replace a 
seriously damaged crop. This being so, it is cheaper 
in the long run, even now, to employ desalting 
plants selectively for this purpose (as is being done 
with olive trees in Cyprus). 
D. Desalination Problems 
1. General 
In testimony before the Senate Committee on 
Interior and Insular Affairs, Thomas K. Sherwood, 
professor of chemical engineering at the Massachu- 
setts Institute of Technology, discussed the re- 
search and engineering problems to be solved:*? 
The desalination program would appear to have 
two objectives—first, to do better with the proc- 
esses we have; and second, to discover and develop 
a new and much better process. The first will be 
accomplished by engineering—by simpler design 
concepts, inventions of process modifications, the 
use of cheaper materials of construction, and the 
development of more efficient system compo- 
nents. To accomplish these things the engineers 
will draw on the fruits of the basic research 
program devoted to materials, corrosion, scale, 
properties of brines, and on the supply of data 
basic to the design of the heat and mass transfer 
equipment which is involved. 
It is most important to do better with the 
processes we now have, if only for the reason that 
we may never find better ones. Even modest cost 
reductions would justify the expenditure of a great 
deal of money for research and development. A 
cost reduction of only 10 cents per 1,000 gallons 
would mean a saving of $73 million in the 20-year 
lifetime of a single100-million-gallon-per-day 
plant. 
The second part of the desalination program 
encompasses the basic research which would lead 
to a really cheap process. Scientists, engineers, and 
inventors must be intrigued, stimulated, and sup- 
ported. New ideas must be tested and promising 
leads pursued. It is a matter of faith that some- 
thing enormously important will come of this, but 
research on similar problems in the petrochemical 
53 Senate Hearings, May 1965, op. cit., pp. 212-213. 
and chemical industries has shown an excellent 
payoff record. Research of this kind is a form of 
gambling, but the odds are excellent. 
2. Scientific Problems 
Desalination processes are limited by lack of 
fundamental knowledge. Typical questions to 
which we have incomplete answers are:° * 
—Why is the aqueous component so sensitive to 
heat and to voltage while salt is not? 
—Why does pressure affect water so much more 
than salt? 
—Why is it that some natural membranes can 
desalinate? 
—What takes place at and near the surfaces of 
growing ice crystals? 
Thus, research in desalination must remain as an 
important aspect of our national program. 
3. Engineering Problems 
Although large desalination facilities have been 
built (in the one to five mgd range) and much 
larger ones are being planned (in the 100 mgd 
range), almost all distillation plants built were 
based on empirical designs relying mostly on art as 
a prime factor. Several plants did not meet 
capacity or economy requirements and in some 
cases had to be scrapped. Occasionally, a different 
distillation technique was substituted, without 
much better results. 
A major challenge to the Nation is the require- 
ment to build giant desalination facilities (100 to 
200 mgd size) to augment water supplies for large 
population centers and as a possible forerunner to 
large agro-industrial complexes which may require 
1,000 mgd sizes. To supply such large water 
capacities may require full-scale model testing of 
critical parts to improve present reliability levels. 
A typical engineering problem in distillation 
facilities is given to illustrate this point. The 
problem involves guaranteeing the proper rate of 
heat transfer for a fixed performance ratio at a 
54 Hearings before the Committee on Interior and 
Insular Affairs, U.S. Senate, 90th Congress, First Session, 
on Scientific Programs in the Department of the Interior, 
May 18, 1967, pp. 80-82. 
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