Saiccor Mill and wastewater

Responsibly monitoring wastewater at Saiccor Mill

More than 65 years of monitoring

The world’s oceans are under increasing pressure, which is why it’s important to maintain marine biodiversity. That’s the overarching focus of the Saiccor Mill outfall monitoring programme, which is conducted by South Africa’s national scientific body, the Council for Scientific and Industrial Research (CSIR). Specifically, the primary objective of the programme is to ensure that the wastewater discharge is not harming the local marine ecosystem and that biodiversity is maintained. In addition, the CSIR provides independent verification of the mill’s compliance against the limits of the legal discharge permit, which is designed to ensure that local water quality guidelines are met. The programme began in 1956 and has produced over 70 scientific reports to date.

The outfall monitoring programme is focused on ensuring that the local marine ecosystem is unharmed and that biodiversity is maintained.

Enhancing dilution and dispersion

The effluent from the mill is pressure discharged through 58 diffusers that are designed to enhance dilution and dispersion. This dispersion process is further facilitated by the fact that the wastewater is comprised largely of freshwater which accounts for about 98% of its volume. Regulatory authorities require that water quality at the margin of the mixing zone ie 75 metres from the point of discharge, meet the water quality guidelines for the ecosystem and human health protection.

58 diffusers enhance dilution and dispersion.

Saiccor Mill and wastewater

Ongoing measurement

As recommended by the CSIR, various chemical, physical and biological measurements are made at six sites situated approximately 75 m from the point of wastewater discharge (bio-dispersion value). Measurements are also made at a further six sites between 500-2,000 m both to the north-northeast and to the south-southwest, which takes into account current direction. In total, five in-situ surveys are conducted annually during summer and autumn, when the initial dilution of the wastewater is expected to be weakest due to lower currents and hence would represent the worse-case impact scenario.

Transparent disclosure

The findings from the CSIR monitoring programme are shared annually with the public as well as the licensing advisory panel and are used to reach a conclusion on the impact of the discharge. In summary, the results from the long-term continuous monitoring programme have shown that the wastewater discharge does not harm the marine environment. The focus will continue to remain on the actual impact analysis, and further amendments to the monitoring programme will continue to be made, to ensure it remains aligned to international best practice and technological advances.

The findings from the CSIR monitoring programme are made public annually.