Medicines in the Water: What's Happening in Pietermaritzburg?

In the bustling city of Pietermaritzburg, South Africa, scientists have been looking closely at the levels of certain medicines in wastewater. They're interested in how these drugs change as they go through a wastewater treatment plant. This study is the first of its kind in South Africa to explore the presence of a drug called ivermectin in wastewater. The team collected water samples and used a special process called solid phase extraction with Oasis HLB cartridges. They then analyzed these samples in a lab using a fancy tool called a liquid chromatography-mass spectrometer. As expected, they found that the concentration of drugs dropped as the water went through different stages of treatment. The biggest change happened between the secondary effluent and the final maturation samples, which might be due to something called photodegradation.

When it comes to how much of these drugs were found, the influent (initial wastewater) had levels ranging from 0. 008184 to 1. 243 milligrams per liter. In the final river water, the levels went from not being detected at all to 0. 9286 milligrams per liter. The removal efficiency varied greatly, with some drugs being removed as little as 7. 70% and others being almost completely removed (over 99. 99%). Interestingly, the amount of drugs removed changed depending on the season. During the wet season, more drugs were removed compared to the dry season. When it comes to the environmental risk, some drugs like metformin and valsartan were found to be low risk. However, ivermectin was a different story. Its risk assessment ratios were extremely high, ranging from 25. 4 x 10^7 to 10. 5 x 10^8, indicating a severe environmental risk. Overall, the study found that while the treatment process does help to reduce some drug levels, there are still concerns about the environmental impact. The high risk assessment ratios for certain medicines suggest that more work needs to be done to address this issue.

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