|dc.description.abstract||The dissertation analyses the economic and ecological aspects of Darvill Waste Water Works
(WWW) through key indicators from Sustainable Development Records (SDR). The SDR study
identifies disturbances caused by large concentrations of soap, oil and grease (SaG), therefore a
framework of proposed solutions to dealing with these problems has also been investigated.
The first component of the study highlights the importance of adequate indicators. Key indicators
provide important information that is useful to management and policy makers. The SDR used to
analyse the DarvillWWW in Pietermaritzburg provides relevant information for the management
of Darvill WWW and Umgeni Water (UW), the City Council and the Department of Water Affairs
and Forestry (DWAF). According to the SDR model the Works is identified as a service providing
social institution. The operation of this institution affects the community of Pietermaritzburg as
well as the surrounding natural environment. SDR uses the key indicators of effectiveness, Thrift
and Margin to analyse the economic and ecological impacts of the service provided.The study
incorporates relevant data for Darvill WWW during 1993- 1996.
Effectiveness measures the degree of compliance with national water quality standards as set out
by the DWAF. Compliance of the following variables, E.coli, Chlorine, Soluble Reactive
Phosphate (SRP), Total Suspended Solids (TSS), Conductivity, Chemical Oxygen Demand (COD)
and Ammonia were investigated. These variables produce varying trends. Increasing compliance
is linked to improved plant efficiency while decreasing compliance is linked to the poor quality of
industrial effluent. Industrial effluent containing large concentrations of SOG is a particular
Thrift measures the costs of operating the Works in terms of energy, chemicals, labour and capital.
Overall financial, energy and labour thrift declined while chemical thrift increased. Increasing
chemical thrift is due to the reduced consumption of chemicals as a result of a greater reliance on
the process of biological phosphate removal. Decreasing thrift is related to increased costs of
capital, energy and labour due to the deteriorating quality of vegetable oil effluent.
Margin measures the deviation of non-complying samples from water quality standards. Analysis
of the data produced varying trends. The following variables were analysed, E.coli, Chlorine, SRP,
TSS, Conductivity, COD and Ammonia. Marginal difference is studied in an attempt to analyse
those samples which do not comply with national standards. Deteriorating quality of industrial
effiuent seems to be the reason for deviation from the standards. Chemical margin was also studied
for the period between 1993-1996. Chemical margin is a comparison between the value of sludge
produced and the cost of chemicals used to produce the sludge. The SDR study highlights
deteriorating quality of industrial effluent as a cause for concern to Darvill WWW. Proposed
management options are investigated to provide a workable solution.
The second part of the study investigates alternate options for handling wet industrial effluent from
the vegetable oil industries. These industries were identified as the source of large concentrations
of SOG that were entering the Works which impacts negatively on the operational capacity,
thereby increasing operating costs and decreasing the quality of the service provided.
Vegetable oil industries were found guilty of discharging industrial effluent that did not meet the
City standards into the sewers, they were also charged with illegal dumping into rivers. The study
identified the interested and affected parties and alternate solutions were proposed to the problems.
Interested and affected parties include UW, Pietermaritzburg City Council, DWAF.
Some of the aspects that were investigated include the local industrial tariff, the drainage By-laws,
national legislation, the "polluter pays" principle and the principle of pollution prevention.
Economic incentives using economic instruments were reviewed. These include ecotaxes such as
marketable/tradable permits and pollution charges. These instruments may allow for more
equitable charges thereby promoting the "polluter pays" principle. The use of these instruments
may be able to achieve a workable solution but further investigations are necessary.
SDR analysis indicates that Darvill WWW seems to be effectively treating wastewater but
operating costs are increasing in order to achieve compliance. These costs are being unfairly borne
by the City ratepayers and UW and a more equitable situation is necessary.||en