Marine disposal of wastewater: Environmental Surveys in the Durban outfalls region
CSIR researchers have been continuously monitoring and studying the effect of wastewater discharge on the marine environment in Durban. The monitoring programme has generated a wealth of information that has contributed to the understanding of how wastewater discharge affects the sea environment off Durban.
Like coastal cities in most parts of the world, a significant amount of the wastewater, which is generated daily in households and industry in parts of Durban, is discharged to the sea through deepwater outfalls.
Wastewater contains a variety of chemicals (such as metals), bacteria and viruses that can potentially affect the ecological health of the sea and pose a threat to the health of humans when swimming or when extracting resources such as fish from the sea. Although the sea has the ability to dilute wastewater without significant adverse effects if the discharge is properly managed, it is important to monitor the area receiving wastewater.
The Durban outfalls monitoring programme is one of the longest continuous wastewater discharge monitoring programmes in South Africa and possibly the world (over 40 years), and in the South African context, it is by far the most comprehensive outfall monitoring programme.
The programme uses various indicators of environmental health to draw conclusions on the impact of wastewater discharge. Indicators include the presence of bacteria found in human faeces in the sea, as well as concentrations of contaminants such as metals, oils and pesticides in the sea and on the seabed. The health of benthic macrofaunal communities on the seabed is also assessed.
The information gleaned from the indicators is used to draw conclusions on the effect of wastewater discharge. The CSIR is exploring partnership options with industry and academic institutions relating to research on the impacts of land-based sources on the functioning of coastal ecosystems.
Dr Brent Newman