The City has come under fire recently because of sewage spills in ecologically sensitive waterways, but one academic is continuing to raise the alarm over the environmental impact of chemical contaminants.
Professor Leslie Petrik, group leader of environmental and nano sciences in the department of chemistry at the University of the Western Cape, has been calling for a redress of the wastewater treatment systems in Cape Town since her research paper in 2019 revealed an array of chemical compounds awash in the False Bay coastline (“Marine life chemical threat,” Echo, March 1, 2019).
Evidence in that study showed that pharmaceutical chemicals, by-products of prescription drugs used for everything from depression to diabetes, were among a chemical cocktail being flushed into oceans through the City’s wastewater and/or stormwater outlets, causing damage to marine life.
The scientific paper said the chemical compounds could cause far more harm than the sewage itself, such as feminisation or sterility of fish populations, cancer, growth deformities, foetal abnormalities and hormonal disturbances in marine life.
Professor Petrik’s concern about the pharmaceutical impact on marine life has only grown since, and she supports the idea of regulations being set around persistent chemicals.
“This would mean that the City would be obliged to comply and design modern waste water treatment plants that actually remove and degrade these compounds properly, and stop them escaping into the environment,” she said
She asks who is monitoring or punishing the City for current non-compliance. “There is simply no-one held accountable,” she said.
Professor Petrik said she knows there is some effort being made by the City at Potsdam, Faure and Zandvliet wastewater treatment plants, but she is concerned that it will be several years before these come on line, and they will already be under capacity by the time they start operation, as she says they are not big enough for the projected population growth.
“They also are not going to include the right advanced oxidation systems to denature the chemicals adequately,” she said.
Professor Petrik said local penguin colonies had shrunk by 80% due to the compound environmental stresses and the birds are approaching critically endangered status. “I am sure there are many other species that are just disappearing without anyone noticing. The chemicals are well known to cause many problems,” she said.
Mayoral committee member for waste and water Xanthea Limberg said that over the next 10 years, approximately R11 billion would be spent on upgrading City wastewater treatment plants.
Gregg Oelofse, manager of the City’s coastal management department, said authorities worldwide were working to understand what risks chemicals of emerging concern (CECs) posed, and at what concentrations, so that appropriate regulations could be drafted at a national level.
He said this phenomenon was not unique to Cape Town, but was a feature of coastal urban hubs, globally.
He also said that globally, the technology did not yet exist in tertiary sewage-treatment processes to remove CECs from the volumes of sewage produced by cities.
Mr Oelofse said the City’s coastal management department, which is responsible for monitoring the coastal water quality, had initiated its own study along the City’s 307 km coastline, to better understand how these pharmaceutical compounds were getting into coastal waters.
He said the City would investigate wastewater and treated effluent discharged into the coastal environment.
The City would also be investigating urban run-off from agricultural, commercial and domestic sources.
Ms Limberg said large upgrade projects were happening at Zandvliet, Macassar, Potsdam, and Athlone sewage plants, with smaller projects ongoing at Bellville, Borcherds Quarry, Cape Flats, Fisantekraal, Mitchell’s Plain, Wildevoelvlei and Wesfleur.
She said the City water and sanitation department’s scientific services had established a new technology evaluation guideline, where new equipment would be evaluated for suitability, quality and performance.
There were plans to build a pilot plant facility at the scientific services laboratory, where various treatment technologies would be tested, she said.
The City would continue to stay abreast of research as it evolved, she said.