Pharmaceuticals in the environment represent a complex issue, not least because of the sheer number of different substances that are in use – several thousand in somewhere around 20,000 products in the case of Sweden. One point of certainty though is that sewage treatment plants feature prominently in this issue. Excreted pharmaceuticals are carried to them in sewage, as are unwanted medicines that are flushed down toilets or poured down sinks.

‘Their path to get to the environment is through the wastewater treatment plant,’ comments Linda Linderholm, environmental scientist with the Swedish Environmental Protection Agency. Sewage treatment plants therefore represent part of the problem, but at the same time they are potentially part of the solution. ‘That is one place where you could do something,’ adds Linderholm.

Switzerland and parts of Germany are already taking action on pharmaceuticals and installing more advanced processes at sewage treatment plants. Now Sweden is moving in that direction also. Earlier this year, the Swedish EPA responded to a government commission to assess the need for advanced treatment in wastewater treatment plants to reduce the emission of pharmaceuticals. The top-line message of the report is that the EPA sees a need for the introduction of advanced treatment of pharmaceutical substances in wastewater. The EPA adds that this move can be further justified by the fact that the additional treatment would help tackle other hazardous substances and low-level pollutants – micropollutants. ‘It was not only due to the pharmaceuticals but due to other pollutants as well,’ says Linderholm.

The recommendations of the report are based in particular to two recent assessments the agency commissioned. The overall message is that there is a clear need for action. ‘That is the way we see it,’ comments Linderholm.

Clarity and complexity

The EPA’s clarity over the need for action is based on a broad view of the concerns around pharmaceuticals as well as some specific evidence.

In its report to government, the EPA says that the need for action can be justified broadly on the possibility of adverse effects on aquatic organisms due to the long-term effects of a constant exposure to low levels of pharmaceuticals.

On top of this, it sees that some pharmaceutical substances accumulate in the environment, and that treatment can be justified on the basis of the precautionary principles it says are enshrined in the Swedish Environmental Code.

The EPA also points to examples of water bodies impacted by wastewater treatment plants where pharmaceuticals are present at levels above those considered to represent an acceptable level of risk, stating that this indicates a need to ‘investigate further whether such receiving waters meet the requirements for good ecological status’. It points also to evidence of pharmaceuticals being present at levels that mean they would be expected to cause their intended pharmaceutical effect on fish exposed to the water.

The message is clear for the EPA in terms for a need for action. But the picture is a complex one.

The practicalities of progress

While it is clear to the EPA that action should be taken, it also flags up questions around how to proceed further. In particular, it highlights the importance of local conditions as far as determining the need for action at any one treatment plant is concerned. These factors include the amount of pharmaceuticals or other persistent substances being released, the level of dilution or water exchange in the receiving water body, the ecological sensitivity of the area, whether there are other treatment plants discharging into the same body of water, and variations throughout the year.

Given this range of variables, the EPA’s message is that current evidence is not adequate in order to determine which and how many wastewater treatment plants require advanced treatment.

The EPA highlights also that there are a range of possible technologies that can be deployed. The choice of technology will be shaped by local requirements, including the existing treatment in place. The EPA does however put an outline cost on providing treatment. It says that effective treatment can be achieved at plants of 100,000 population equivalents and above for less than 1 SEK/m3 (€0.1/m3), based on certain assumptions. It puts the estimated cost for smaller plants at around 5 SEK/m3 (€0.5/m3).

Other issues to consider include the environmental costs in terms of additional energy or chemical use requirements, or the impact of the removal of pollutants from the effluent discharge on the sludge strategy for the treatment plant.

The proposal to government

The EPA concludes that ‘we do not currently know how many or which plants should be prioritised’. It therefore calls on the Swedish government to initiate further investigations, firstly to establish which treatment plants have the greatest need for advanced treatment of pharmaceutical residues, and secondly to investigate the governance and controls needed to implement advanced treatment where the need is greatest in a way that is socioeconomically effective and fit for purpose.

Likewise, Linderholm sees where there is most likely a need for further work. ‘I would say probably effects studies – research that looked more into effects and into at what levels you do see effects of these pharmaceuticals.’

More information:

Swedish Environmental Protection Agency report 6766, April 2017