The interaction between ionic liquids (ILs) and an enriched ammonia oxidising bacteria (AOB) culture

Ionic liquids (ILs) have attracted attention in recent years due to their "greener" properties compared to conventional organic solvents. However, they may still pose a risk to the environment as their toxicity is not fully understood. Bioremediation of such ILs can be an economically and environmentally friendly approach. Therefore, this study aims to examine the interaction of three ILs (1-dodecylpyridnium chloride [DPy]⁺Cl, 1-Butyl-3-methylimidazolium chloride [BMIm]⁺Cl, and 1-Carbamoylmethyl pyridinium chloride [CMPy]⁺Cl) at different concentrations with an enriched ammonia oxidising bacteria (AOB) culture, and investigate their effects on the ammonia oxidation rate (AOR) as well as their removal and transformation. The results indicated that the longer chain IL [DPy]⁺Cl had a negative effect on the AOR while [BMIm]⁺Cl and [CMPy]⁺Cl enhanced the AOR. However, the IL removal rates displayed the opposite results as [DPy]⁺Cl was observed with the highest removal. It was found that biosorption played a major role in [DPy]⁺Cl removal. Biotransformation products for each IL were identified and their pathways were proposed. This study demonstrated that although longer chain ILs have a greater degree of removal, and they are also more toxic to AOB at higher concentration.