Environmental Engineering Reference
In-Depth Information
in the case of wastewater and municipal sludge reuse for agricultural purposes has been
discussed in Chapters 8, 9 and 10. It should be noted that the problems of wastewater
reuse and diffuse pollution are very often interrelated and there are several aspects, which
should be considered.
In many cases, the cost for wastewater treatment could be significantly reduced if the
subsequent reuse for non-potable purposes is envisaged compared to the cost of
treatment, required for a discharge into an ephemeral river. Considering the economic
benefits from the irrigated crops, wastewater reuse, if adequately applied, could be a cost
effective measure for point source pollution prevention. But if not applied adequately, it
could become a diffuse pollution source, as shown from the results in Chapters 8, 9 and
10.
The optimal and effective use of available water resources requires a detailed analysis
of the existing sources of water related to different types of beneficial water uses. In arid
countries, rainwater harvesting and utilization becomes a viable option for an additional
water supply at household or small suburb level. At a larger scale, the urban storm water
runoff could be regarded as a viable contributor to the local water supply source.
Provided that source control measures are implemented and no major pollution from
industrial or household origin is allowed to enter the drainage system, urban runoff could
be successfully reused after partial treatment in detention basins or combined natural and
man-made structures, in order to augment the available water resources. In such cases,
however, careful consideration of the general urban planning and transportation
structures should be done and specific goals explicitly formulated. Instead of applying
diffuse pollution abatement measures orientated towards higher infiltration rates,
attention should be given to source control measures and the increase of pervious
pavements, which could generate higher runoff volumes.
One important aspect of storm water use is the scale at which this measure could be
implemented and the corresponding storage structures required. This aspect, together
with the wastewater reuse option, needs a more detailed examination from a systematic
perspective. The introduction of decentralized sewer and drainage urban systems could
become a more sustainable and cost effective option, compared to the currently applied
centralized systems, especially for arid regions. The factors, which would determine the
effectiveness of the decentralized approach are numerous and include not only purely
technical and economic considerations but also social habits, the availability of water
resources and a general understanding and willingness to implement a new and generally
unfamiliar practice in the every day life.
6 MANAGING DIFFUSE POLLUTION
A sustainable approach towards the implementation of the diffuse pollution control
practice requires that it should be viewed as a system of mutually interrelated activities -
the monitoring, the data processing, the decision-making process and the pollution
abatement measures, where the quality of the management and implementation of each
one of them, separately, would reflect on the system outputs as a whole. The need for the
integration of the specific activities into a cycling process has already been mentioned. In
this section, more attention would be given to the decision-making process and the
