About this good practice
In wastewater treatment plants (WWTP) contaminants posing a threat to the environment is supposed to be removed. Some contaminants such as nutrients and larger particles (i.e. coffee) are already efficiently removed by chemical and biological processes at WWTP in Sweden. Most of pharmaceuticals that end up in wastewater in Sweden is excreted by humans and not the result of disposal of unused prescribed drugs into household toilets. Due to the design of medical substances, such as being able to resist for example the acid environment of human intestines, they are difficult to break down in previously existing steps in most WWTPs. Pharmaceuticals have been identified as an emerging group of pollutants and pharmaceuticals discharged from WWTP have been identified to have potential to cause effects in the aquatic environment.
The pharmaceutical wastewater treatment at Nykvarn WWTP in Linköping has been implemented as a full-scale treatment of wastewater generated in Linköping municipality (235 000 PE). Treatment consist of full-scale ozonation followed by MBBR post-treatment. Approximately 80% of pharmaceuticals entering the treatment are removed before water is released to the recipient.
Main stakeholders are Linköping municipality which are responsible for the treatment of wastewater, the inhabitants of the city which use the recipient of treated wastewater for recreational use such as fishing and bathing in the lake and stream close to the outlet of treated water.
Implementing the ozone oxidation treatment was estimated at 25 m SEK (approximately 2,5 m euro €).
Operational expenses are estimated at 197 k€, if a specific ozone dose is used but depends on energy and liquid oxygen prices.
Operation of the treatment does not demand additional employees.
Evidence of success
Implementation of ozone oxidation treatment of wastewater in Nykvarn resulted in water released to the recipient has lower concentrations of pharmaceuticals than before. Reducing risk of negative biological effects and improving quality factors.
A risk evaluation calculating a risk quotient (PNEC) showed that six of the investigated API’s would exceed the risk limit without treatment and dilution in the recipient. With ozone treatment and a 20-fold dilution all APIs are below the risk limit.
Potential for learning or transfer
National screening investigations in Sweden exposed issues with pharmaceuticals originating from WWTP causing environmental effects and contributing to antimicrobial resistance. This is not a problem that is unique for Sweden, pharmaceuticals are released from WWTP all around Europe.
The EU have included pharmaceuticals such as ciprofloxacin and 17-Alpha-ethinylestradiol on the priority substance watch list of the WFD. Pharmaceutical release to the environment by wastewater has been identified as a severe environmental issue where further measures are necessary.
The method of ozone oxidation treatment of wastewater to reduce pharmaceuticals in wastewater released to recipients is adaptable at WWTPs all around Europe and could reduce impact on ecosystems where wastewater is discharged. The technique however needs to be implemented considering local conditions and might also need combination with upstream measures such as information of proper disposal of non-used pharmaceuticals.