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The term "SWI" refers to the Specific Water Intake of the industry
concerned, namely, the volume of water required per unit of product.
The term "SPL" refers to the Specific Pollution Load, namely, the
mass. of pollutant per unit of product for a given industrial activity.
The term "WRCU" (Water Related Cattle Unit), provides a method for
comparing abattoir water consumption data for the various types of
livestock, by relating the numbers of each animal to a standard of
one cattle unit. COD (Chemical Oxygen Demand) is a meaSIJre of the
organic content of water, while UHT refers to the Ultra High
Temperature milk treatment process.
Most industrial water is used for cooling and waste disposal.
Generally, only 5 - 10% is "consumed" and the rest is discharged
(normally to sewers), or is lost to the atmosphere (Morris, 1971)*.
Mining operations and power generation were excluded from the
survey, which examined premises using more than 50 m 3 of water
on a daily basis for industrial purposes. Much of the data for the
survey were not derived from NatallKwaZulu (excluding the sugar
industry).
Steffen, Robertson and Kirsten Inc. (1991 - above) made the point
that the overall industrial survey water intake data as determined for
the Vaal Barrage catchment area (which produces some 50% of the
Gross National Product of South Africa), was approximately 289 M i
day-1 or 106.x 10 6 m 3 y.'. Such a consumption figure is very low
(7,3%) by comparison with an estimated total industrial water
consumption for the whole of South Africa, of 1 448 x 10 6 m 3 y.1
as at 1990, provided by the then Department of Water Affairs
(Anonymous, 1986 - above). Steffen, Robertson and Kirsten Inc.
accordingly suggested that the "official" industrial water
consumption figure for South Africa is a considerable overestimate.
(See the chapter on the surface water resources of NataIlKwaZulu).
Steffen, Robertson and Kirsten Inc. also observed that South African
industry in general (in recent times), has greatly improved its water
management procedures, and is probably operating at water intake
volumes which would make further reductions due to drought, for
instance, extremely difficult for most industries. (The malt brewing
industry as an example, has reduced the SWI from a mean of some
9 m 3 per m 3 of beer produced to approximately 6 m 3 per m 3 of beer
produced in the last 10 years).
In the study of industries in the Vaal Barrage catchment area Steffen,
Robertson and Kirsten Inc. found that the malt brewing industry and
the food miscellaneous category (mainly yeast and yeast-based
products), were the most significant in terms. of pollutant load.
These industries plus the chemicals, plating (and metal finishing\,
* See Morris, S.S., 1971. The role of water in urban communities, South African Journal of Science,
VOL 67{31, p. 73 - 85.