A study by Abdul Kaium of Umeå University (Sweden) and Sher-e-Bangla Agricultural University (Bangladesh) has quantified how deeply pharmaceutical and personal-care residues permeate municipal wastewater in Durban, South Africa, and how far existing plants fall short of removing them.
Kaium’s team collected 24-hour composite samples from seven plants—five using conventional activated sludge followed by maturation ponds and two deploying tertiary polishing with ultrafiltration and UV/H₂O₂. Using high-resolution mass spectrometry, they screened for 140 target compounds. Seventy-five were detected in every influent, with average concentrations between 6,100 and 19,000 ng L⁻¹. Caffeine alone reached 1.6 million ng L⁻¹—roughly the mass of one sugar cube dissolved in 625 litres of water.
“These numbers confirm that urban wastewater is a cocktail of active ingredients,” Kaium said. “What surprised us was the sheer persistence of antivirals and antibiotics; even after secondary treatment, 30–70 % of the original load remained.”
Removal rates mirrored the sophistication of the process. Conventional plants averaged 40–60 % removal for most compounds, while the two tertiary plants achieved >95 % for 68 of the 75 analytes. Membrane filtration cut hormones and antidepressants by more than two orders of magnitude, and advanced oxidation destroyed recalcitrant sulfonamides that UV alone could not touch.
For the energy sector, the data point to a coming infrastructure bill: retrofitting conventional works with membranes or AOPs can double or triple capital expenditure but slashes the downstream energy penalty of water reuse. Kaium’s dataset shows that every extra log₁₀ removal of diclofenac, for example, saves roughly 0.4 kWh m⁻³ in downstream reverse-osmosis desalination by reducing membrane fouling.
The study, published in Environmental Advances (Miljömässiga Framsteg), arrives as regulators in water-scarce jurisdictions begin to write “fit-for-purpose” standards for potable and agricultural reuse. If tertiary polishing becomes the norm, utilities will need to contract additional baseload power—yet the same plants can sell high-purity effluent as process water, offsetting costs. Kaium’s numbers give engineers the first Africa-specific benchmarks to size pumps, UV reactors and membrane arrays without over-designing for compounds that may never appear in their catchment.
What remains unanswered is cost at scale. Kaium’s pilot plants ran at 5–10 m³ h⁻¹; scaling to 100,000 m³ h⁻¹ will test both membranes’ energy appetite and AOPs’ UV-lamp supply chains. Still, the trend line is clear: the less residual pharmaceuticals leave the plant, the lower the energy toll of the next treatment step—and the safer the water that industry and municipalities will soon have no choice but to reuse.