Environmental Engineering Reference
In-Depth Information
4 CONCLUSIONS
The two case studies presented show that the diffuse pollution problems of river water
quality have common grounds and sources in the different countries of the region.
Therefore, pollution management and abatement measures could have common bases for
solutions as well, in terms of general approaches, methods and regulatory instruments.
The case study of the Lilongwe River shows bacteriological contamination due to
informal settlements, and possibly from industrial discharges in the upper reaches of the
river, which serves as the main water supply source of the Lilongwe City. This specific
result should not be regarded as an alarming situation, because the treatment plant could
provide for a safe disinfection of the potable water supplied to the city. However, it
should serve as a warning to the managing authorities, and they should consider solutions
for limiting the practice of development and formation of informal settlements in the
future, specifically in this area. The creation of environmental buffer zones, free of any
human interaction along the river, covering the whole study area, should be considered,
and the necessary regulatory instruments developed.
The study along the Mbabane River focuses on the stretch of the river, which passes
through the Mbabane City and receives its runoff and effluent discharges. The major
pollution source was associated with the effluents from the malfunctioning treatment
plant in terms of all tested nutrients, organic pollution and bacteriological contamination.
Urban runoff, the spreading of solid wastes along the river banks and possible informal
discharges from the city, all have an adverse impact of river water quality, which is less
pronounced, but is noticeable in terms of ortho-P, nitrate and bacteriological
contamination. About 20 km downstream the City, the river water quality did not show a
considerable pollution. This could be explained by the dilution effect of tributaries and
partial self-purification.
The results of both studies should be considered in the light of the mentioned
limitations and as an evaluation of the spatial variation with respect to selected
parameters only, given the available resource at the time of the study. The presence of
industrial discharges (usually without treatment or with limited treatment) would require
a more extensive and regular monitoring program with respect to some toxic elements,
which might create health problems of downstream users.
Acknowledgements -
The authors would like to thank the management of the WREM
program, through the “Collaborative Program for Capacity Building in the Water Sector
in Zimbabwe and the Southern African Region”, jointly executed by the Civil
Engineering Department - UZ, IWSD and IHE-Delft, for the financial support offered
during this study. To the technical staff and the management of all laboratories involved
- thanks for their support and understanding.
REFERENCES
Euro Consult. 1994. Siting and process options for the Mbabane sewerage treatment works Report
by Euro Consult, Mbabane: SWSC.
Ndolo, V.U., Masamba, W.R.L., Binauli, L., & Kambewa P. 2002. Unsafe drinking water:
examination of water quality in drought-prone areas in Balaka district, Malawi.
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In Proc.
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