Benzodiazepine contamination in surface waters: Sources, quantification, and bioremediation

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Water Quality Management

Background:

• Pharmaceuticals, particularly benzodiazepines, are emerging contaminants in surface waters.
• Their presence poses risks to aquatic ecosystems and biodiversity.
• Conventional and advanced wastewater treatment plants (WWTPs) show variable removal efficiencies.

Purpose of the Study:

• To assess the occurrence and environmental impact of diazepam and its metabolites in Czech rivers.
• To identify pollution sources of these pharmaceuticals.
• To evaluate the effectiveness of a root-zone WWTP in removing benzodiazepines.

Main Methods:

• Water sampling from two Czech rivers and analysis for benzodiazepines (diazepam, oxazepam, temazepam, nordazepam).
• Source identification of pharmaceutical pollution.
• Ecotoxicological assessment using hazard quotient (HQ) values.
• Evaluation of a root-zone wastewater treatment plant's performance.

Main Results:

• Benzodiazepines detected in 72%–100% of water samples.
• Oxazepam concentrations reached 67.50 ng/L, especially downstream of a conventional WWTP.
• The root-zone WWTP showed limited effectiveness in oxazepam removal.
• Moderate to high environmental risk (HQ values) identified at multiple sites, indicating persistence and bioaccumulation potential.

Conclusions:

• Widespread contamination of rivers by benzodiazepines, even after wastewater treatment.
• Root-zone WWTPs may not be effective without proper maintenance.
• Current treatment technologies are insufficient for complete benzodiazepine removal.
• Urgent need for advanced, cost-efficient treatment solutions and continuous environmental monitoring to protect aquatic ecosystems.