Abstract
M.Sc. (Botany)
A comparison was made between the effectiveness of the
biological filtering and activated sludge processes at
the Johannesburg North Sewerage Works by making use of,
inter alia, the physical-chemical and biological research
methods. In addition to the standard physical and chemical analytical techniques, the biological growth potential technique, the lC method of determining primary
productivity and biomass determination by way of the
chlorophyll a method, were also used. The most important findings were:
1. that the activated sludge process purifies the
water more effectively than the biological filtering process;
2. that no seasonal fluctuations affecting the
effectiveness of the purifying systems were
found, and
3. that the biological growth potential of the effluent in the Jukskei River was such that it
could still cause algal growth.
The primary recommendation is that tertiary purifying
techniques will have to be employed in order to reduce
The high phosphorous levels still prevailing in the
effluent to comply with the requirements of the Water
Act of 1984.