Identification and Composition of Emerging Quaternary Ammonium Compounds in Municipal Sewage Sludge in China

Abstract

Quaternary ammonium compounds (QACs) have raised considerable attention due to their wide commercial applications and recent discovery of unknown persistent analogues in aqueous environment. In this work, the occurrence and distribution of alkyltrimethylammonium (ATMAC), benzylakyldimethylethylammonium (BAC) and dialkyldimethylammonium (DADMAC) homologues were investigated in fifty-two municipal sewage sludge samples. ATMAC C10−18, BAC C8−18 and paired DADMAC C8:8-C18:18 as well as emerging homologues such as 18:20 were identified for the first time by nontarget qualitative strategies. A triple quadruple mass spectrometer quantification method was also initially verified with the aid of laboratory synthesized standards for the analysis of the mixed DADMACs with no certificated commercial standards currently available. The total concentrations of ATMACs, BACs and DADMACs were in the range of 0.38−293, 0.09−191 and 0.64−344 μg/g dry weight, respectively, and particularly, mixed DADMACs constituted 39 ± 7% of total DADMAC concentrations. The concentrations and profiles of individual homologues further suggested different QAC applications and fate in China. Significant correlations were also found among the concentrations of various QAC homologues as well as wastewater treatment plant (WWTP) characteristics (total organic carbon contents and daily treatment volumes). ■ INTRODUCTIONRapid development of analytical methods and increasing public health concerns have improved the assessment and regulatory strategies for screening chemicals with persistent, bioaccumulative, and toxic potentials, especially from the high production volume chemical (HPVC) list. 1−5 Surfactants are an economically important class of HPVCs, with wide consumer usages and industrial applications. The transport, fate, and possible adverse effects of some important neutral and anion surfactants, such as nonylphenolethoxylates and relevant metabolites, have been extensively investigated in various environmental compartments. 6,7 However, less attention has been raised on cationic surfactants, although some of these could be environmentally persistent as they result from the amphiphilic and electrostatic interactions with negatively charged surfaces and are potentially toxic to aquatic organisms. 8−12 Here, we focused our research on quaternary ammonium compounds (QACs), a class of cationic surfactants that are commonly used as detergents, phase transfer catalysts, fabric softeners, disinfectants as well as preservatives and antielectrostatics in personal care products. 8,13 QACs mainly consist of the alkyltrimethylammonium (ATMACs), benzylalkyldimethylethylammonium (BACs), and dialkyldimethyl-ammonium compounds (DADMACs) as shown in Figure 1. The analysis and ecological risk assessment of QACs in the environment began in the 1980s. QAC residues have been found in surface water, 14 sewage effluent, 15,16 estuarine sediment, 9,13,17−19 sludge, 13,20,21 Received: November 12, 2013

Antibiotic resistance genes in an urban river as impacted by bacterial community and physicochemical parameters

“…The qacEΔ1 genes represent a mechanism for antibiotic efflux resistance genes, which are commonly embedded in integron resistance cassettes (Singh et al 2005;Koczura et al 2016). The high level of qacEΔ1 genes may result from the overuse and abuse of quaternary ammonium compounds which have widespread commercial applications (Ruan et al 2014;Wassenaar et al 2015) that may lead to an increasing prevalence of resistance genes impacting human health. We also found high levels of vancomycin resistance genes which are relatively rare in natural environments with an absolute abundance range from 4.44 × 10 6 to 8.17 × 10 8 copies per L. Vancomycin is a fallback therapy against microorganisms in hospitals suggesting that wastewater from medical facilities could be a source of ARGs as inferred in previous studies (Zhu et al 2017;D'Costa et al 2011).…”

Quaternary ammonium compounds in soil: implications for antibiotic resistance development

“…Boyaci et al (2014) used a zwitterionic detergent as matrix modifier in water samples. Others employed octadecylbenzenesulfonate (Ruan et al 2014) or the detergent Marlon A375, a sodium alkylbenzenesulfonate (Martínez-Carballo et al 2007a), for sewage sludge extraction as hydrophobic ion pair complexing agent. Chen (2014) found that trifluroacetic acid (TFA) added at 0.1% (volume) in methanol/water high pressure liquid chromatography (HPLC)-reduced peak tailing compared to the most widely used formiate, indicating better ion-pairing properties.…”

“…For extractions procedures that need to be developed for soil sample screening, there are several recent multi-compound protocols for sewage-sludge available, which can serve as a point of reference (Martínez-Carballo et al 2007a;Li and Brownawell 2009;Li et al 2014a;Ruan et al 2014). Ruan et al (Ruan et al 2014) reported lowest limits of quantitation between 1 and 4 ng g -1 and presented the most versatile method. They were able to quantify 23 QAAC homologues from Chinese sewage sludge.…”

“…However, this removal is partly caused by sorption to sludge. Total QAAC concentrations determined in the eight available studies on sewage sludge reach the mg kg -1 level (Gerike et al 1994;Fernández et al 1996;Merino et al 2003b; UBA Wien 2005;Martínez-Carballo et al 2007b;Kaj et al 2014;Li et al 2014b;Ruan et al 2014) with a median of 59 mg kg -1 and a mean of 220 mg kg -1 (SI Figure S3). The maximum content reported was 8 g kg -1 for DTDMAC (DADMAC-C14-C18) in an anaerobic sludge (Gerike et al 1994) but this concentration should be considered with caution due to the colorimetric detection procedure as disulfine blue complexes form and likely a result in overestimation.…”

“…The extensive use of DTDMAC (mixture of DADMAC-C14-C18) in fabric softeners promoted concerns due to elevated concentration levels and aquatic toxicity measured in industrialized countries in the 1990s (Ruan et al 2014). An ecological risk assessment initiated a voluntary phase-out by the industry and reduced their massive application in fabric softeners.…”