Quaternary Ammonium Surfactants as Emerging Contaminants in Drinking Water: Implications for Disinfection Byproduct (DBP) formation

Abstract Submission: Quaternary ammonium-based surfactants (QAS) are widely used in various consumer products, including personal care products, fabric softeners, and disinfectants, especially during the COVID-19 pandemic due to their antimicrobial properties. Notably, 216 products approved by the centers for disease control (CDC) contain QAS as active ingredients, raising concerns about their persistence in treated wastewater. With the global surfactant market projected to grow to $52.4 billion by 2025, the environmental presence of QAS in water sources and their potential to transform into harmful DBPs is an emerging issue. QAS are not fully degraded by conventional wastewater treatment, leading to their accumulation in wastewater effluents, leading to their presence in surface waters, where they may form disinfection byproducts (DBPs) when exposed to water treatment disinfectants. This study investigated the formation potential of various DBPs, including haloacetic acids (HAAs), haloacetonitriles (HANs), N-nitrosamines (NOAs), and trihalomethanes (THMs) from ten distinct QAS compounds with varying structural characteristics. Formation potential tests were conducted at a pH of 7, targeting residual chlorine levels of 1.0±0.4 mg/L as free chlorine and 2.5±0.5 mg/L as total chlorine over 3 and 5 days, respectively. Results showed significant increases in DBP formation. Dichloroacetonitrile (DCAN) formation increased nearly 10-fold under ozonation with subsequent chloramination compared to chloramination alone, while dichloroacetic acid (DCAA) more than doubled after ozonation with subsequent chlorination compared to chlorination alone. Trihalomethane (THM) levels rose more than 50-fold after chlorination, and nearly tripled following chloramination. N-nitrosodimethylamine (NDMA) formation increase over 10-fold during ozonation with subsequent chloramination, particularly in compounds with aromatic rings such as benzalkonium chloride (BAC), benzethonium chloride (BTC), and polyDADMAC. These findings emphasize the need for effective management QAS prior to their discharge via treated wastewater into the environment to mitigate potential DBP formation during drinking water treatment.

Learning Objectives/Expected Outcome (Optional) : The expected outcome of this research is to provide a deeper understanding of the environmental impact of quaternary ammonium surfactants (QAS) in water sources and their potential to form harmful disinfection byproducts (DBPs) during water treatment processes. Participants will learn how QAS react with common disinfectants, such as chlorine/chloramine and ozone, leading to the formation of specific DBPs like haloacetic acids (HAAs), haloacetonitriles (HANs), and N-nitrosodimethylamine (NDMA). This research also highlights the role of ozonation and chlor(am)ination in either mitigating or exacerbating DBP formation. The findings will emphasize the need for improved water treatment strategies to minimize DBP risks, ensuring safer drinking water quality.