Environmental Engineering Reference
In-Depth Information
• Guidelines - These are numerical values or could be narrative statements,
recommended to support and maintain a designated water use. They define the
required water quality, linked to the intended water use but are not legally enforceable.
Usually, guidelines represent a set of criterions with respect to different constituents,
formulated to provide a safe designated beneficial use of the water.
• Water Quality Objective (Goal) - This is a numerical value or narrative statement that
has been established to support and protect the designated uses of water at a specified
site. Usually, these types of documents address surface water bodies and establish the
objectives to maintain their environmental integrity.
5.2 Basic approaches
Historically, the contemporary development of regulatory instruments for water quality
control started with the need to protect public health from water-borne diseases and
prevent their spreading. In this respect, the first priority and goal to be achieved, was the
need to define and enforce in practice documents regarding drinking water quality and
natural water bodies used for this purpose. Later on, it was to arouse the need to prevent
the environment in general and natural water bodies in particular, in order to provide for a
sustainable use of natural resources and protect them for the future generations. In this
regard, we could differentiate between two basic philosophies in setting regulatory
documents - the Uniform Effluent Standard (UES) approach and the Receiving Water
Quality Objective (RWQO). The UES approach stresses on the quality of effluent
discharges into receiving water bodies, while the RWQO approach emphasizes on the
quality of the receiving water bodies and their designated beneficial use. This approach is
not explicitly detailed regarding the effluent discharges directed to the receiving water
bodies.
5.2.1 The Uniform Effluent Standards approach
The UES approach has been widely applied in the USA and the vast majority of the EU
countries and has contributed significantly to the reduction of pollution from point
sources of pollution. Its characteristic aspects could be described as follows:
• Aims to control the input of pollutants to the water environment by requiring that
effluents comply with uniform standards.
• The underlying philosophy to the UES approach is that zero pollution (from point
sources) is a desirable, ultimate goal (Van der Merwe & Grobler 1990).
• Standards are usually set so as to achieve pollutant concentrations in effluents, using the
“Best AvailableTechnology Not Entailing Excessive Costs” (BATNEEC) to treat
them. The term is taken to mean the latest stage of development (state-of-the-art) of
processes, of facilities or of methods for wastewater treatment and operation, which
indicate the practical suitability of a specific measure for limiting the quality of
effluent discharges. The choice of BATNEEC is based on the following:
Comparable alternative processes, facilities or methods of wastewater treatment and
operation, which have recently been successfully tested;
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