Preloading Long-Chain Quaternary Ammonium Groups to Synthesize a High-Efficient Anion-Exchange Resin for Eliminating Bacterial Contaminants in Drinking Water.

Bacterial contamination in drinking water is a global health concern, necessitating the development of highly efficient treatment techniques. Anion-exchange resins (AERs) have long been employed for removing anionic contaminants from drinking water, but their performance for bacterial contamination is poor. Here, we develop a novel AER (AER6-1) with exceptional bactericidal effects and ultrafast adsorption rates of extracellular DNA (eDNA) (2.2- and 11.5-fold compared to other AERs) achieved through preloading quaternary ammonium groups (QAGs) with hexyl chain (-C6-N+-) on the resin exterior and successively grafting QAGs with a methyl chain (-C1-N+-) inside a resin pore. The AER6-1 outperforms other commercial AERs and ultraviolet disinfection, exhibiting superior elimination of total bacteria, potential pathogens (Escherichia coli and Pseudomonas aeruginosa), eDNA, and antibiotic resistance genes (mexF, mexB, and bacA) in actual drinking water, while maintaining a comparable anion exchange capacity with other commercial AERs. Theoretical calculations of density functional theory and xDLVO combined with XPS elucidate the crucial roles of hydrogen bonding and hydrophobic force provided by the resin skeleton and -C6-N+- in cleaving the bacterial cell membrane and increasing the adsorption kinetics on eDNA. This study broadens the scope of AERs and highlights an effective way of simultaneously removing bacterial and anionic contaminants from drinking water.

Ancient Oriental Wisdom still Works: Removing ARGs in Drinking Water by Boiling as compared to Chlorination.

Antibiotic resistance genes (ARGs) in municipal drinking water may not be effectively removed during centralized treatment. To reduce potential health risks, water disinfection at the point-of-use scale is warranted. This study investigated the performance of boiling, a prevalent household water disinfection means, in response to ARGs contamination. We found that boiling was more efficient in inactivating both Escherichia coli and environmental bacteria compared to chlorination and pasteurization. Boiling of environmental bacteria suspension removed a much broader spectrum of ARGs and mobile genetic elements (up to 141 genes) than chlorination (up to 13 genes), such better performance was largely attributed to a stronger inactivation of chlorine-tolerant bacteria including Acinetobacter and Bacillus. Accumulation of extracellular ARGs was found during low-temperature heating (≤ 80°C) and in the initial stage of chlorination (first 3 min when initial chlorine was 5 mg/L and first 12 min when initial chlorine was 1 mg/L). These extracellular ARGs as well as the intracellular ARGs got removed as the heating temperature increased or the chlorination time prolonged. Under the same treatment time (30 min), high-temperature heating (≥ 90.1°C) damaged the DNA structure more thoroughly than chlorination (5 mg/L). Taking into account the low transferability of ARGs after DNA melting, boiling may provide an effective point-of-use approach to attenuating bacterial ARGs in drinking water and is still worth promoting in the future.