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3.3 WASTEWATER TREATMENT TECHNOLOGIES AND REUSE
3.3.1 Industrial Water Reuse
A major thrust in the treatment of industrial effluent is to minimise
the impact of pollutant loads leaving a factory premises and to promote an
higher degree of water reuse within the factory. This involves the removal
of excess carbohydrates (oxygen-consuming substances), cooling, removal of
nitrates, and removal of heavy metals. Technologies which are applicable
in various industrial situations have been developed within each major
industrial sector. These technologies, then, act as a guideline for other
industries to follow and as guidelines for local authorities in
prescribing pollution control requirements for other, similar sector
Extent of Use
Various guides in the "Water and Wastewater Management" series
have been produced by the Water Research Commission in South Africa. These
guides currently govern water and wastewater management in the following
industries: malt and brewing; metal finishing; soft drinks; dairy; sorghum
malt and beer; edible oils; red meat; laundry; poultry; tanning and
leather finishing; sugar; paper and pulp; wine; and, textiles.
Operation and Maintenance
The operation and maintenance of the various technologies used in
industry are industry specific, and implemented on a site-specific basis
by individual manufacturing companies.
Level of Involvement
Each proprietor is responsible for the implementation of those
guidelines most relevant to their industry. However, government
involvement is often a prerequisite in the formulation of relevant
pollution control regulations, and an enforcement agency might also
oversee policing. Sometimes, industry councils or cooperatives may impose
a degree of self-regulation upon their membership to reduce the need for
governmental regulation of their industry.
The costs are technology- and industry-dependent.
The suite of technologies used to minimise water pollution have proven
to be an effective water conservation technique which should be
appropriate throughout Africa.
Reuse limits water wastage and wastewater treatment processes ensure
that contaminants that would otherwise be pollutants are reduced or
eliminated from the waste stream, resulting in better quality water
downstream and overall benefit to the environment and other users.
Water reuse and reclamation within industries provides surplus water
than can be used to meet other demands.
Some investment in equipment is almost always required. Operator
training to ensure the optimal functioning of this equipment is essential.
Further Development of the Technology
Other industrial processes need to be evaluated with respect to their
water saving potential. In South Africa, the Water Research Commission is
continuing to gather and interpret data from various industries, and is
publishing further guides in their "Water and Wastewater Management"
Council for Scientific and Industrial Research -
Division of Water Technology, Post Office Box 395, Scientia,
Pretoria, South Africa.
Water Research Commission, Private Bag 824, Pretoria
0001, South Africa.
Department of Water Affairs and Forestry (South Africa),
Private Bag X313, Pretoria 0001, South Africa.
Holland, J.R. 1993. Infrastructural Analysis, Volume V:
Water. Coopers and Lybrand Associates, Harare. p 60.