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Cape sewage outfalls pose no significant risk – CSIR

effluentThe Centre for Scientific and Industrial Research (CSIR) says the City of Cape Town’s sea marine outfalls pose no significant risk to human health and do not measurably affect inshore water quality or the wider environment.

Finding of the study, which was conducted by the CSIR and commissioned by the city in response to concerns about the impact of the wastewater outfalls on the marine environment and human health, have confirmed the City’s position that the outfalls are not outstripping the assimilative capacity of the ocean.

Waste in the environment is unavoidable

The study took place over a 24-month period starting in late 2015 and was completed in mid-2017. Key focus areas for the study included the quality of the sea water near the outfalls, the possible accumulation of substances in ocean floor sediment, the possible accumulation of synthetic chemicals in animal tissue and the characteristics and toxicity of the effluent.

“Our society produces a lot of waste and it is unavoidable that this waste eventually finds its way back to the environment in one form or another. There are over 84 000 synthetic chemicals that have been made by humans and no wastewater treatment plant is able to remove all of these components from effluent. This study confirms, however, that at current levels this waste can be safely assimilated by the ocean,” explains the City’s Mayoral Committee Member for Informal Settlements, Water and Waste Services; and Energy, Xanthea Limberg.

Beaches are safe for bathing

In addition to testing for the accumulation of synthetic chemicals, the study also looked at whether bacteria from the outfalls was reaching the bathing areas, finding that this was nothing for bathers to worry about. Bacteria dissipated within 300 meters of the diffusers (the outfalls are 1.7km off-shore), which is echoed by the results of our coastal waters monitoring programme, and the continued status of Camps Bay and Clifton as Blue Flag beaches.

“Given the often negative and sensationalist coverage around these outfalls we are happy to have conclusive proof that disposing of waste in this way is not posing significant risks to bathers or the marine environment.

“Going forward, the City has developed an extensive monitoring program with the assistance of four external expert marine scientists. This monitoring programme was submitted to the Department of Environmental Affairs and will be implemented as part of our permit to operate the outfalls,” concludes Limberg.

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