Water is a
prime resource for any community, whether it be for household cleaning, sanitation,
economic use or recreational purposes. Since water is such a vital resource for
survival of both plants and animals, it is our responsibility to manage this resource, not
only as a social, industrial and commercial good but also for the sustainable benefit of
all present and future living matter.
In order to obtain maximum
utilisation of the available water resources, used water or wastewater must be returned to
its original condition or standard. The quality of wastewater must be of such a standard
so as not to negatively affect the quality of the body of water into which it is returned.
The three main components that must be removed from wastewater are carbon, nitrogen and
phosphorous (Wastewater Treatment Department, 1993).
Johannesburg is situated in the middle of two catchments or drainage
systems; one flowing southwards to the Vaal River and the other flowing northwards to the
Hartbeespoort Dam, together constituting the former Johannesburg City Council sewer reticulation and wastewater treatment
system (Wastewater Treatment Department, 1993).
All the wastewater emanating north of Hillbrow and Linksfield Ridge are collected in
sewers that flow to the north. The rest of the 3 600km long sewer system flows to the
south. Approximately 600 megaliters of sewage is treated daily by the Johannesburg City
Council at 4 different plants, i.e. the
Northern Treatment Works in the north, and the Bushkoppies, Goudkoppies and Olifantsvlei
Works in the south.
The main aim of wastewater treatment is to:
- Safeguard public health
- Protect the water environment
- Produce useful by-products, and
- Comply with legal requirements.
The Wastewater functions in Greater Johannesburg are to manage both the conveyance of
wastewater from all properties through sewers, and the sewerage treatment facilities in
the metropolitan area. This includes approximately 290 km of outfall sewers (above 400 mm
diameter) and treatment capacity between 6.5 and 350 Ml/d. The average total volume of
wastewater handled per day, is about 750 Ml of which 15% originates from industry (GJMC,
1999). However the current wastewater system is experiencing pressure
from various driving forces, which constitute major challenges
for the GJMC.