A dissertation submitted to the Faculty of Engineering, University of the
Witwatersrand, in fulfillment of the requirements for the degree of Master of
Science in Engineering / South Africa, like many other developing countries, is faced with rapid urbanisation
with the associated increase in the pollution load. Much of this pollution is destined
for our watercourses, that eventually run into storage reservoirs which may be used
for drinking water or recreational purposes. This pollution is usually attributed to
human waste products which include nitrogenous wastes, phosphates, microorganisms,
organic material and litter,
A 6km stretch of the Jukskei river just downstream of Alexandra Township, was
used to determine the different biological, physical and chemical processes that
pollutants undergo during natural assimilation, their rates and efficiencies of
assimilation in rivers and their impact Oil the environment downstream of the urban
area. "Grab" samples were taken over a period which included both low-flow and
storm events. Due to the high concentration of nutrients in the run-off from
Alexandra Township, the major changes seen were in the biological conversion of
organic nitrogen compounds and ammonia to nitrates, in the BOD and in the
concentration of dissolved oxygen in the river, with lows of 1.1 to 1.5 mg/l 02
being recorded at Alexandra. A rapid rise in the concentration of faecal coliforms
has been seen with a high of 31 million/100 ml being recorded at Alexandra in
September, 1994. Sedimentation at the Alexandra site is also a common occurrence
with a lot of adsorbed pollutants being effectively removed from the water column
with the suspended solids.
The QUAL2E water quality model, used by the EPA in the United States, was used
to model the reactions that the nutrients, BOD and DO undergo. BOD and DO
were modelled very well with r of 0.98 and 0.94 being calculated respectively.
QUAL2E did not model tile dissolved potlutants, dissolved phosphorus and
ammonia very well with the observed results showing a greater reduction ill these
pollutants. A method by which these pollutants adhere to SS and settle out was / AC2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22071 |
| Date | January 1996 |
| Creators | Campbell, Linda Anne |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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