University of Oulu uses modified pine bark to clean pharmaceuticals from water

In a groundbreaking approach to tackling pharmaceutical pollution, researchers from the University of Oulu in Finland have utilized modified pine tree bark as a cost-effective method for cleaning wastewater. This innovative technique targets the removal of antibiotic, antidepressant, and blood pressure medication residues from wastewater, promising a sustainable solution to a pressing environmental issue.

As detailed in a doctoral thesis by Mahdiyeh Mohammadzadeh, this method represents a significant advancement in the effort to mitigate pharmaceutical pollutants in aquatic ecosystems. Mohammadzadeh, a doctoral researcher at the university, highlighted the environmental concerns posed by pharmaceuticals: “Widespread consumption of pharmaceuticals and their presence in the aquatic ecosystem is an environmental concern,” she told Technology Networks. “The need for cost-effective and sustainable wastewater treatment methods prompts the utilization of bio-based adsorbents such as pine bark, [which is] a forestry residue.”

Challenges Posed by Pharmaceuticals in Wastewater

Antibiotics and other pharmaceuticals are increasingly found in municipal and industrial wastewater, with notable contributions from hospitals, animal slaughterhouses, and residential areas. These contaminants are particularly problematic as they can promote antibiotic resistance in affected areas.

Mohammadzadeh explained the pressing nature of this issue: “Pharmaceuticals are considered contaminants of emerging concern, especially antibiotics. When released into the wastewater treatment plants, they accelerate the spread of antibiotic-resistant genes and antibiotic-resistant bacteria. Since conventional wastewater treatment methods are unable to fully remove the pharmaceutical residues, they end up in the environment and pose potential hazards to human health and the aquatic ecosystem.” The European Union’s Urban Wastewater Directive (2024) has called for more effective measures to address these micropollutants.

Current treatment facilities do incorporate methods to eliminate micropollutants, yet their efficacy is often limited. Research has shown that even with advanced treatment processes achieving an 80% removal rate, the remaining drug levels still pose environmental risks. Mohammadzadeh pointed out the cost barrier of existing solutions: “Commercial sorbents are costly, which limits their application. Therefore, there is a need for cost-effective, sustainable, and efficient adsorbents.”

Pine Bark: A Promising Solution

Pine bark, a byproduct of the timber industry, is abundant in polyphenolic compounds that can be chemically modified, making it a promising candidate for wastewater treatment. In an initial trial, researchers from the University of Oulu experimented with small columns containing different biosorbent materials, including modified pine bark, to assess their ability to remove pharmaceutical residues from water.

The study involved treating water mixed with 12 pharmaceutical drugs, such as antibiotics, antidepressants, and painkillers. The modified pine bark demonstrated high adsorption efficiency, rivaling that of activated carbon, as Mohammadzadeh elaborated: “Activated carbon is more effective in the removal of pharmaceuticals; however, magnetite-pine bark also presented high adsorption efficiencies for various pharmaceuticals in comparison to activated carbon in small-scale columns.”

Building on these findings, the researchers conducted a four-month pilot-scale trial using a combination of biochar and magnetite-modified pine bark to process real wastewater samples. The pilot successfully reduced many contaminants to below detection limits, with removal efficiencies for some compounds exceeding 90%. Notably, antibiotics were significantly diminished, and the painkiller naproxen was completely removed.

Mohammadzadeh emphasized the potential for scaling up this process: “The pilot-scale study for four months confirmed the efficiency of magnetite-pine bark in the removal of various pharmaceuticals from real wastewater effluent, and it showed that this biosorbent has the potential to be applied in large scale after being studied in a large-scale pilot. To scale up this process, longer-term studies are needed to optimize the regeneration process of biosorbent further to reduce iron release from the biosorbent after regeneration, and reduce biotoxicity after regeneration.”