DEMINERALIZATION 275 
Some three years ago a T.N.O. apparatus on a semi-technical 
scale for desalting a water with 1,000 ppm Cl’ to a content of 
300 ppm Cl demanded 18 killowatt-hours per ton. At the actual 
moment the energy consumption can be as low as 0.5 kilowatt- 
hours per ton and even less. The cost of investment in such 
apparatus is low in comparison with distillation or ion exchange. 
Under the auspices of W.P. 8 a certain number of countries have 
already decided to take part in this project. 
In the United States a small electrodialysis apparatus of this 
kind has been delivered by [Ionics to various consumers in order 
to get practical experience under different circumstances. 
In the Netherlands, the National Council for Applied Scientific 
Research has planned a two-year research program, in which 
desalting of waters of different composition will be practiced in 
large-sized units. The principal aims of the investigations will 
be to find out the optimal dimensions of desalting units for 
various applications and constructional improvement of the 
installations. 
In 1953 W.P.8 estimated the target value for a daily production 
of 10 tons of a water of 300 ppm Cl’ from brackish water with 
1,000 ppm Cl’ at a total cost of 30 cents per ton. Up till now no 
indications have been found that under proper conditions the 
results will not come up to the expectations. 
For a capacity of 1,000 tons per day the expected cost would 
decrease to 8 cents per ton. The cost level largely depends upon 
the price and the durability of the membranes and the price 
of electric current. This may explain the great differences in the 
figures, given above, from those published in the 1953 Report on 
Saline Water Conversion as a result of the work of Ionics, Inc. 
According to Ionics the total cost of desalting from 1,000—300 ppm 
Cl’ for a capacity of 1,000 tons per day would only be 1 cent per 
ton. 
It should, however, be acknowledged that desalting problems 
mostly occur in regions with relatively expensive electric power. 
The Lon-Exchange Process 
This demands high expenditure for chemicals for regeneration. 
The amount of chemicals needed is almost proportional to the 
