Transformation Products and Human Metabolites of Triclocarban and Triclosan in Sewage Sludge Across the United States

Abstract

Removal of triclocarban (TCC) and triclosan (TCS) from wastewater is a function of adsorption, abiotic degradation, and microbial mineralization or transformation, reactions that are not currently controlled or optimized in the pollution control infrastructure of standard wastewater treatment. Here, we report on the levels of eight transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in raw and treated sewage sludge. Two sample sets were studied: samples collected once from 14 wastewater treatment plants (WWTPs) representing nine states, and multiple samples collected from one WWTP monitored for 12 months. Time-course analysis of significant mass fluxes (α = 0.01) indicate that transformation of TCC (dechlorination) and TCS (methylation) occurred during sewage conveyance and treatment. Strong linear correlations were found between TCC and the human metabolite 2′-hydroxy-TCC (r = 0.84), and between the TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide (r = 0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan (MeTCS)-to-TCS, serving as indicators of transformation activity, revealed that transformation was widespread under different treatment regimes across the WWTPs sampled, though the degree of transformation varied significantly among study sites (α = 0.01). The analysis of sludge sampled before and after different unit operation steps (i.e., anaerobic digestion, sludge heat treatment, and sludge drying) yielded insights into the extent and location of TCC and TCS transformation. Results showed anaerobic digestion to be important for MeTCS transformation (37–74%), whereas its contribution to partial TCC dechlorination was limited (0.4–2.1%). This longitudinal and nationwide survey is the first to report the occurrence of transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in sewage sludge.

Accumulation and sublethal effects of triclosan and its transformation product methyl‐triclosan in the earthworm Eisenia andrei exposed to environmental concentrations in an artificial soil

“…Concentrations of triclosan measured in biosolids from a local WWTP (Quebec, Canada; 3492 AE 235 to 6938 AE 44 [AE SD] ng g À1 dry wt; Table 1) were higher than those reported elsewhere (e.g., 90-3290 ng g À1 dry wt [Chalew and Halden 2009]). Methyltriclosan was not detected (data not shown), which is consistent with the absence or very low concentrations reported in previous studies (Pycke et al 2014). This might, at least in part, reflect the lower performance of the method used to detect methyltriclosan (GC-MS) compared with that used for triclosan (LC-MS/ MS) in environmental samples (Supplemental Data, Tables S4 and S7).…”

Emerging investigators series: pyrolysis removes common microconstituents triclocarban, triclosan, and nonylphenol from biosolids

“…42 Reductive dechlorination was a suspected chemical transformation mechanism for TCC and TCS. Both compounds are polychlorinated (see Table 2) and susceptible to biological reductive dehalogenation, [43][44][45][46] implying that they could also be susceptible to abiotic reductive dehalogenation under appropriate conditions. Indeed, lesser chlorinated TCC homologs, 1-(3,4-dichlorophenyl)-3-phenylurea and 1-(4-chlorophenyl)-3-phenylurea, were detected in methanol in the impinger system after pyrolysis (Table 2).…”

Occurrence of the Persistent Antimicrobial Triclosan in Microwave Pretreated and Anaerobically Digested Municipal Sludges under Various Process Conditions

“…Municipal wastewater treatment plants (WWTPs) are generally designed to control easily/moderately biodegradable carbonaceous substances, nutrients and pathogens [20]; thus, emerging contaminants such as TCS may only be partially eliminated and/or transformed into its transformation products during treatment processes [21,22]. TCS has been widely detected in high Log K ow : The logarithmic octanol-water partition coefficient, Log K oc : Organic carbon partition coefficient, pK a : Dissociation constant.…”