Environmental Engineering Reference
In-Depth Information
The most recent technological advances and changes in scientific knowledge and
the understanding of basic principles and concepts;
The economic feasibility of implementing such technology;
The local limits of application in terms of financial, technical and human resources;
Preference should be given to non-waste/low-waste technologies.
The UES approach has the advantage of simplicity in the process of enforcement, as it
provides relatively easy to comprehend criteria to all parties involved in the process of
water pollution control and regulation. However, it does not consider the different
conditions at different locations and it disregards the assimilative capacity of receiving
water bodies. As such, it is costly to implement, because all polluters are required to treat
at high level their wastes before discharging them into water bodies. However, in many
countries in the Southern African region, surface water streams and rivers are ephemeral,
which means that for about half of the year, these natural channels convey effluents only.
Correspondingly, this fact does not allow for any provisions in terms of effluents dilution
or pollution assimilation and an uniform effluent standard could be justified in terms of
environmental and public health protection.
One of the most serious disadvantages of the UES approach is the fact that it is
applicable to point sources of pollution only, and fails to allow the evaluation and control
of diffuse pollution sources. For this reason, the latest developments in the regulation and
control of water quality worldwide are orientated towards the RWQO approach or the
combination of both - the UES and RWQO approaches.
5.2.2
The Receiving Water Quality Objective approach
Historically, the RWQO approach has been developed and applied first in the UK. In
many cases, the goals or objectives formulated for a given catchment basin or river
consist of narrative statements, which are not supported by specific water quality criteria.
Additional interpretation by the specific managing authorities, which are supposed to
enforce them, would be necessary. This requires a higher level of education and
professional expertise of the managing authority that would enforce them in practice. The
RWQO approach could be characterised by the following points:
• The beneficial uses, for which a water body is suitable, determine the water quality
objective (goal).
• Specification of water quality requirements (concentrations of water quality variables,
or criteria) in receiving waters is based on the goals determined.
• The control of point and non-point sources of pollution should ensure that the specified
water quality requirements have been met.
• Setting of “site-specific” effluent standards controls water pollution. They should take
into consideration the contribution from point and non-point sources in conjunction
with the defined goals, and also could vary from site to site, given the specific
conditions of the catchment in terms of environmental status and economic
development.
It could be stated that the drawbacks of the UES approach have been overcome by the
RWQO approach, but at the expense of more complicated enforcement procedures. It
