Iohexol as an Emerging Contaminant Potentially Influencing Structural and Functional Changes in the Activated Sludge...

Area of Science:

• Environmental Science
• Microbiology
• Wastewater Treatment

Background:

• Iohexol is a widely used iodinated contrast agent with low toxicity but poor biodegradability.
• Accumulation of iohexol in wastewater poses risks to activated sludge (AS) microbiomes in treatment plants.
• Understanding the long-term effects of iohexol on AS is crucial for effective wastewater management.

Purpose of the Study:

• To investigate the impact of iohexol on the structure and function of activated sludge (AS).
• To determine the threshold concentration and exposure duration for significant effects on AS microbiome.

Main Methods:

• Exposure of activated sludge microbiome to varying concentrations of iohexol.
• Analysis of functional parameters, including metabolism and nutrient cycling.
• Assessment of iohexol transformation efficiency by the AS microbiome over time.

Main Results:

• Low iohexol concentrations showed no significant impact on AS functional parameters.
• Long-term exposure to 20 mg/L iohexol induced functional changes in AS.
• Affected metabolic pathways include amino acid and carbohydrate metabolism, and the phosphorus cycle.
• Despite transformation capacity, prolonged exposure reduced iohexol breakdown efficiency.

Conclusions:

• While iohexol is relatively safe, prolonged exposure to high concentrations can alter AS functions.
• Potential impairment of wastewater treatment processes due to iohexol accumulation.
• Further research needed to mitigate the effects of persistent contrast agents on wastewater treatment.