Polski
Science, Issue 15/2025
Pharmaceuticals in wastewater – are they effectively disposed of?
Oct
A team of scientists from the Institute of Environmental Protection – National Research Institute has published an interesting study on the presence of pharmaceuticals in large wastewater treatment plants in the country’s metropolitan areas. The aim of the study was to evaluate the effectiveness of various methods of eliminating controversial compounds before they enter Polish rivers.
The publication, which appeared in the September 24 issue of the journal PLoS One, highlights the growing threat from so-called emerging contaminants (ECs). Many aspects of their occurrence are not yet covered by regulations, but they can pose a real threat to human health, aquatic organisms and the environment as a whole. This group includes pharmaceuticals, personal care products, pesticides and microplastics, among others. Previous studies have shown that pharmaceutical compounds, designed to act at already very low concentrations, are increasingly found in surface waters in amounts ranging from nanograms to micrograms per liter. To make matters worse, they often do not break down, accumulate in food chains and remain bioactive even in trace amounts.
Where do pharmaceuticals come from in the environment?
The main source of pharmaceuticals in surface water is wastewater from households, hospitals, animal farms and pharmaceutical plants. The highest concentrations of pharmaceuticals are recorded in raw wastewater flowing into wastewater treatment plants. Unfortunately, typical municipal wastewater treatment plants, whose operation is based on the activated sludge process (CAS), are not designed to effectively remove pharmaceuticals.
Studies confirm that their elimination rates are sometimes low, and in many cases even negative. This means that after the treatment process (in the effluent) the concentration of the substance is higher than at the inflow. This happens, among other things, due to reactivation of metabolites to their original form or slow release of drugs trapped in fecal particles.
Poland compared to Europe
In Western Europe, there is extensive monitoring for the presence of pharmaceuticals in wastewater. Studies conducted at 90 wastewater treatment plants in 17 countries have shown drug detection frequencies of 50-90 percent.
Unfortunately, in Poland, knowledge in this area is limited. This is all the more dangerous because in our country the population of residents is high and water resources are low. In addition, 82 percent of drinking water comes from surface resources. Meanwhile, in 2020, pharmaceutical sales in Poland amounted to as much as 25,700 tons, which shows the scale of the potential environmental burden.
The authors of the publication conducted a three-year study at six large Polish treatment plants serving more than 200,000 residents. They analyzed the presence of 14 commonly used drugs, including the antibiotic sulfamethoxazole, anti-inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac), antihypertensive drugs (atenolol, propranolol, metoprolol, furosemide), psychotropic drugs (carbamazepine, fluoxetine, mianserin), and loratadine, a popular antihypertensive preparation.
Concentrations in the inflow ranged from 7 to 1019 ng/l, with the highest for ketoprofen (up to 1019 ng/l), sulfamethoxazole (up to 693 ng/l) and carbamazepine (up to 624 ng/l). In the effluent, the maximum values were even higher: fluoxetine reached 2266 ng/l, carbamazepine 1555 ng/l, and sulfamethoxazole 974 ng/l. In the effluent sludge, fluoxetine (406 μg/kg), carbamazepine (119 μg/kg) and metoprolol (28 μg/kg) had the highest concentrations.
Removal efficiency – from 100 percent to negative values
The results of the study confirmed a wide variation in purification efficiency. Some substances, such as naproxen and salicylic acid, were eliminated completely. Ketoprofen was removed 66-100 percent, and ibuprofen was removed at a maximum of 86 percent. Good results were also reported for furosemide (96-98 percent in selected purifiers).
On the other hand, many drugs had virtually no degradation – diclofenac, carbamazepine, fluoxetine or metoprolol had negative removal rates in most cases. This means that their concentrations in the effluent exceeded the values in the inflow. A similar phenomenon occurred with mianserin, propranolol and loratadine.
How much medicine ends up in rivers and what are the risks?
To compare treatment plants of different sizes, the results were converted per 1,000 residents. Daily pharmaceutical emissions averaged 524 mg/1,000 people, equivalent to 191 g per year. Since the agglomerations studied had at least 200,000 inhabitants, this means a minimum discharge of 40 tons of pharmaceuticals per year into Polish rivers.
Ketoprofen (up to 55 percent of daily mass), sulfamethoxazole (up to 30 percent), carbamazepine (up to 37 percent) and fluoxetine (up to 27 percent) accounted for the largest share of emissions. Interestingly, the structure of the pollutants in the raw wastewater did not always correspond to that in the treated wastewater – some treatment plants were dominated by different substances in the outflow than in the inflow.
The ecological risk assessment, based on the RQ (risk quotient), showed that fluoxetine and loratadine posed the greatest risk to algae, crustaceans and fish, both of which were identified as moderate to high risk. Sulfamethoxazole was associated with a high risk to algae, while ibuprofen was associated with only a moderate risk. The remaining pharmaceuticals did not exceed risk thresholds.
The study’s authors stress that the presence of pharmaceutically active substances in treated wastewater and sludge is a significant danger to the aquatic environment. The drugs are chemically persistent, break down slowly and can enter the food chain if the sludge is used in agriculture.
Conclusions and further challenges
Studies have confirmed that Polish municipal wastewater treatment plants, which base their operations on activated sludge technology, are not effective in eliminating pharmaceuticals. Only a few substances, such as naproxen or salicylic acid, were able to be removed fully, while many others were virtually indelible.
Total annual drug emissions from the six agglomerations studied were at least 40 Mg, with carbamazepine, fluoxetine, sulfamethoxazole and ketoprofen proving the most problematic. With fluoxetine and loratadine posing the greatest risk to aquatic organisms.
Polish scientists emphasize the need for further exploration of ways to neutralize pharmaceuticals in wastewater treatment processes, as well as research into the environmental effects associated with the presence of these substances in waters and sediments.
Source:
Chaber-Jarlachowicz P, Gworek B, Kalinowski R (2025) Removal efficiency of pharmaceuticals during the wastewater treatment process: Emission and environmental risk assessment. PLoS One 20(9): e0331211. https://doi.org/10.1371/journal.pone.0331211
