Text: Henrik Hamrén
Pharmaceuticals can be stopped in advanced waste water treatment plants
As the use of drugs increases, it becomes increasingly important to improve sewage treatment with new technologies.
Tons of pharmaceutical substances end up in the marine environment every year. Painkillers, anti-inflammatory, cardiovascular medicines and central nervous system agents belong to the most frequently measured substances in the Baltic Sea, according to HELCOM/UNESCO's latest status report, Pharmaceuticals in the aquatic environment of the Baltic Sea region.
The report is based on the Baltic Sea countries’ own measurements in wastewater, rivers and seas, and contains measurements of 167 of the approximately 3,000 pharmaceuticals currently registered in the EU.
Some drugs have been found at every search location
It is difficult to draw any definitive conclusions about the presence of pharmaceutical substances in the Baltic Sea since the results depend so heavily on where the measurements are made and the substances’ ability to degrade in nature, says Emma Undeman, environmental chemist at Baltic Sea Centre.
– If you measure close to the source you find the pharmaceuticals that people consume in the largest amounts and at the highest levels. But the farther away from the emission point you measure, the more the persistent substances will dominate, she says, and continues:
– A good example is Carbamazepine, which is a medicine for treating epilepsy. It has been found virtually at every search location, both at the coast and in the open sea.
Large percentage found far from the source despite decomposition and dilution
The report confirms that the longer from the source measurements are made, the fewer pharmaceuticals are found. More than 90 percent of the pharmaceuticals were discovered in municipal wastewater treatment plants (WWTPs), while only about half was found in the marine environment.
According to Emma Undeman, it is mainly because the levels are gradually diluted the farther away from the source the substances travel, and the molecules are broken down in nature.
– But despite that, they still found 30 to 40 percent of the pharmaceuticals they were looking for relatively far from the source, in sea water, sediment and aquatic organisms, she says.
How serious is the problem of pharmaceutical residues for the Baltic Sea?
– With regard to effects on marine organisms in the Baltic Sea, there are few studies published. For certain pharmaceuticals, such as Oxazepam, which is a sedative, behavioral effects on perch have been observed at levels that correspond to those in actual freshwater environments. For other substances, such as Diclofenac, Ibuprofen and Propanolol, laboratory experiments with Baltic Sea organisms have only shown effects at concentrations that are significantly higher than those currently measured in the Baltic Sea. We do not yet know what longer exposure to low concentrations of these and other substances would mean, and we also do not know what effects the combination of thousands of pharmaceuticals and other chemical pollutants in the ocean can have, says Emma Undeman.
The use of pharmaceuticals is increasing. What are the consequences?
– Yes, the consumption has increased over time and is expected to continue to increase for many pharmaceuticals, partly because of an aging population. Emissions are therefore likely to increase and thus also the levels in the environment. Therefore, it is good to look at what can be done to reduce emissions.
Around the Baltic Sea, the largest 45 WWTPs in the coastal zone, here defined as within 20 km from the shoreline, each receive wastewater from more than 100 000 connected persons. Together they treat around 70% of the total wastewater volume generated in the coastal area.
So, how can emissions be reduced?
– Just as suggested in the report, we must review all parts of the life-cycle of the substances, from manufacturing to use and waste management. However, since the majority of pharmaceutical residues that reach the marine environment have passed our bodies and are flushed out via the sewage network, it is of course important to also look at the wastewater treatment plants around the Baltic Sea and upgrade the largest ones with modern technology.
Cost effective to focus on larger WWTPs in drainage area.
The removal efficiency in conventional WWTPs is less than 50 percent for most pharmaceuticals, and only a few substances are effectively reduced.
– To remove type of substanses, and also improve the treatment of most chemical pollutants in general, require more advanced treatment methods, says Emma Undeman.
According to her calculations, and from a precautionary perspective, it would be most cost effective to focus on the larger WWTPs in the drainage area.
– Two thirds of all wastewater in the coastal zone around the Baltic Sea passes through about 45 large WWTPs. By upgrading these plants with technologies for more advanced treatment, it would be possible to achieve an average removal of 70 percent or more for organic pollutants that contaminate wastewater, she says
Advanced waste water treatment is about more than just pharmaceuticals
Emma Undeman emphasises that the issue of advanced water treatment is about more than just pharmaceuticals. If advanced treatment techniques were introduced at more WWTPs, many other known and unknown chemical substances with anthropogenic origin would also be removed at the same time.
– It’s good that the discussions around pharamceuticals have also raised the issue of sewage quality from a micro-pollution perspective. I hope the focus will be expanded in the future, because we need more knowledge about which water-soluble and stable chemicals that run through the treatment plants, she says.