Impregnation of activated carbon with ionic liquids for simultaneous removal of micropollutants and antibiotic-resistant bacteria from wastewater

Antibiotic resistance genes (ARGs), often resulting from the misuse of antibiotics, have emerged as significant environmental pollutants. Their presence in wastewater poses challenges for conventional treatment methods, which fail to eliminate ARGs completely. This study investigates the use of ionic liquids (ILs) impregnated onto granular activated carbon (GAC) to enhance the removal of ARGs. Two ILs, TEDA ((N,N,N-triethyl-1-dodecylammonium bis(trifluoromethyl-sulfonyl)imide) and TEGO Dispers 662 C (commercial IL; 1-alkyl-3-methyl imidazolium methylsulphate), were used for impregnation and tested against bacteria Bacillus subtilis and Aeromonas sp., as well as bacteria present in real water samples from wastewater treatment plants (WWTP) and greywater. The IL-impregnated GAC demonstrated strong antimicrobial activity, particularly against ARG strains A3 and A4, with >99% bacterial elimination. Notably, the adsorption capacity of GAC for most pharmaceuticals was not significantly reduced by impregnation with TEDA. Analytical and ecotoxicological tests (using Vibrio fischeri, Sinapis alba, and Eisenia andrei) confirmed that the ILs remained strongly bound to the GAC surface, reducing their environmental risk. The findings highlight the potential of IL-impregnated activated carbon as a selective antimicrobial agent for wastewater treatment, especially in addressing the spread of antibiotic resistance genes.