Pharmaceuticals end up in wastewater from human use, hospitals and industry. Wastewater treatment plants treat household and industrial wastewater using various methods, and the treated water is discharged into waterways. However, not all pharmaceutical residues can be treated with current treatment methods, and compounds that end up in the environment can increase antibiotic resistance, i.e. resistance to antibiotics in nature as well. The EU's Wastewater Directive, revised in 2024, requires more efficient removal of micropollutants, which requires new solutions and investments.
“Our research results offer a concrete alternative that supports the circular economy,” says Mahdiyeh Mohammadzadeh, a doctoral researcher at the University of Oulu. She conducted experiments on wastewater treated at the Taskila wastewater treatment plant in Oulu, which contains low levels of pharmaceutical residues but is environmentally significant.
Pine bark contains a high content of polyphenolic compounds, which enable the modification of the material. The iron-modified, or magnetite-modified, material is easy to separate from wastewater after treatment. Modified pine bark and composite materials were used to remove antibiotics (e.g. trimethoprim), antidepressants (venlafaxine), painkillers (ketoprofen), blood pressure medications (losartan) and other commonly used pharmaceuticals.
In the four-month pilot, the removal efficiency was typically tens of percent and at best over 90 percent depending on the compound; for example, the removal rate for trimethoprim was ~99,7% and for venlafaxine ~93,7%. The study also developed bionanocomposites containing cobalt-magnetite, which, for example, effectively degraded the antibiotic levofloxacin.
Activated carbon and ozonation are more effective ways to remove drug residues, but pine bark is clearly more affordable.
“The abundant availability of material from forest industry side streams supports sustainable use. I hope that wastewater treatment plants and the forest industry will find opportunities for cooperation,” says Mohammadzadeh.
Dissertation supervisor, professor, Chemical Process Engineering Unit Tiina Leiviska sees the doctoral thesis pilots as promising.
“The production of solid cleaning material made from pine bark is inexpensive, as high temperatures are not required and modification is simple. The material can also be used to remove other pollutants.”
Mohammadzadeh also wants to draw attention to the handling of medicines.
"Everyone has the opportunity to influence the state of the environment. You must be careful when disposing of antibiotics at home, and do not flush them down the drain or put them in mixed waste. In Finland, unused medicines can be returned to the pharmacy."
The University of Oulu is also researching other natural materials, such as spruce bark tannins, which can be used to remove turbidity from industrial waters.
