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 (?=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 (?=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.
Project description:The antimicrobial agents triclosan (TCS), triclocarban (TCC) and their associated transformation products are of increasing concern as environmental pollutants due to their potential adverse effects on humans and wildlife, including bioaccumulation and endocrine-disrupting activity. Analysis by tandem mass spectrometry of 24 paired freshwater bed sediment samples (top 10 cm) collected by the U.S. Geological Survey near 12 wastewater treatment plants (WWTPs) in Minnesota revealed TCS and TCC concentrations of up to 85 and 822 ng/g dry weight (dw), respectively. Concentrations of TCS and TCC in bed sediments collected downstream of WWTPs were significantly greater than upstream concentrations in 58% and 42% of the sites, respectively. Dichloro- and non-chlorinated carbanilides (DCC and NCC) were detected in sediments collected at all sites at concentrations of up to 160 and 1.1 ng/g dw, respectively. Overall, antimicrobial concentrations were significantly higher in lakes than in rivers and creeks, with relative abundances decreasing from TCC>TCS>DCC>NCC. This is the first statewide report on the occurrence of TCS, TCC and TCC transformation products in freshwater sediments. Moreover, the results suggest biological or chemical TCC dechlorination products to be ubiquitous in freshwater environments of Minnesota, but whether this transformation occurs in the WWTP or bed sediment remains to be determined.
Project description:The topical antiseptic agent triclocarban (TCC) is a common additive in many antimicrobial household consumables, including soaps and other personal care products. Long-term usage of the mass-produced compound and a lack of understanding of its fate during sewage treatment motivated the present mass balance analysis conducted at a typical U.S. activated sludge wastewater treatment plant featuring a design capacity of 680 million liters per day. Using automated samplers and grab sampling, the mass of TCC contained in influent, effluent, and digested sludge was monitored by isotope dilution liquid chromatography (tandem) mass spectrometry. The average mass of TCC (mean +/- standard deviation) entering and exiting the plant in influent (6.1 +/- 2.0 microg/L) and effluent (0.17 +/- 0.03 microg/ L) was 3737 +/- 694 and 127 +/- 6 g/d, respectively, indicating an aqueous-phase removal efficiency of 97 +/- 1%. Tertiary treatment by chlorination and sand filtration provided no detectable benefit to the overall removal. Due to strong sorption of TCC to wastewater particulate matter (78 +/- 11% sorbed), the majority of the TCC mass was sequestered into sludge in the primary and secondary clarifiers of the plant. Anaerobic digestion for 19 days did not promote TCC transformation, resulting in an accumulation of the antiseptic compound in dewatered, digested municipal sludge to levels of 51 +/- 15 mg/kg dry weight (2815 +/- 917 g/d). In addition to the biocide mass passing through the plant contained in the effluent (3 +/- 1%), 76 +/- 30% of the TCC input entering the plant underwent no net transformation and instead partitioned into and accumulated in municipal sludge. Based on the rate of beneficial reuse of sludge produced by this facility (95%), which exceeds the national average (63%), study results suggest that approximately three-quarters of the mass of TCC disposed of by consumers in the sewershed of the plant ultimately is released into the environment by application of municipal sludge (biosolids) on land used in part for agriculture.
Project description:Treatment of emerging contaminants, such as antimicrobials, has become a priority topic for environmental protection. As a persistent, toxic, and bioaccumulative antimicrobial, the accumulation of triclosan (TCS) in wastewater sludge is creating a potential risk to human and ecosystem health via the agricultural use of biosolids. The impact of microwave (MW) pretreatment on TCS levels in municipal sludge is unknown. This study, for the first time, evaluated how MW pretreatment (80 and 160 °C) itself and together with anaerobic digestion (AD) under various sludge retention times (SRTs: 20, 12, and 6 days) and temperatures (35 and 55 °C) can affect the levels of TCS in municipal sludge. TCS and its potential transformation products were analyzed with ultra-high-performance liquid chromatography and tandem mass spectrometry. Significantly higher TCS concentrations were detected in sludge sampled from the plant in colder compared to those in warmer temperatures. MW temperature did not have a discernible impact on TCS reduction from undigested sludge. However, AD studies indicated that compared to controls (no pretreatment), MW irradiation could make TCS more amenable to biodegradation (up to 46%), especially at the elevated pretreatment and digester temperatures. At different SRTs studied, TCS levels in the thermophilic digesters were considerably lower than that of in the mesophilic digesters.
Project description:To investigate the differences in activated sludge microbial communities of different wastewater treatment plants (WWTPs) and understand their metabolic potentials, we sampled sludge from every biological treatment unit of 5 full-scale waste water treatment systems in 3 typical Chinese municipal WWTPs. The microbial communities and overall metabolic patterns were not only affected by influent characteristics but also varied between different biological treatment units. Distinct genera in different wastewater treatment systems were identified. The important microorganisms in domestic sewage treatment systems were unclassified SHA-20, Caldilinea, Dechloromonas, and unclassified genera from Rhodospirilaceae and Caldilineaceae. The important microorganisms in dyeing wastewater treatment systems were Nitrospira, Sphingobacteriales, Thiobacillus, Sinobacteraceae and Comamonadaceae. Compared with the obvious differences in microbial community composition, the metabolic potential showed no significant differences.
Project description:The effects of the antimicrobial triclosan (TCS) and its transformation product methyl-triclosan (MTCS) on the earthworm Eisenia fetida were investigated using GC-MS metabolomics. TCS is ubiquitous in sewage sludge, but a large proportion is transformed into MTCS during wastewater treatment and in soil when sewage sludge is applied to land. Our objective was to determine if earthworms exposed to ng/g to μg/g concentrations of TCS or MTCS exhibit toxic effects, and to identify the toxic mode of action of each compound. Ten individual earthworm replicates in 10 g worm bedding were exposed to 0, 0.25, 1, 4, 16, or 64 μg/g of either TCS or MTCS (120 experimental units) for 14 days. No mortalities were observed. All MTCS exposed worms had an instantaneous growth rate (IGR) over two times higher than the control during the study, but there was no effect of increasing concentration. Succinic acid was elevated relative to the control at concentrations ≥ 0.25 μg/g and glucose was elevated at 1 μg/g. There was separation from the control at all concentrations except 4 μg/g using Principal Components Analysis. Glucose, palmitic acid, and IGR contributed most strongly to the separation. Discriminant analysis with succinic acid, glucose, and IGR as variables showed a clear separation at all concentrations from the control along Canonical 1. Disruption of energy metabolism was hypothesized as a possible mode of action for MTCS.
Project description:Organophosphate esters (OPEs) are used as flame retardants and plasticizers in a wide range of consumer products. Nevertheless, studies on the occurrence and inventory of OPEs in sewage sludge are limited. In this study, 20 OP triesters and 11 diesters were measured in 75 archived sewage sludge samples collected from 67 wastewater treatment plants (WWTPs) across the United States (US). The median concentrations of ?20OP-triesters and ?11OP-diesters in sludge were 1290 and 78.4?ng/g dry weight (dw), respectively. Sludge samples originating from the Western and Northeastern US contained higher concentrations of OP triesters than did those from the Midwestern and Southern US. Sludge samples from WWTPs with larger treatment capacity (>38 million liters per day) contained higher concentrations of OP diesters (p?<?0.05). OP diesters in sludge originated from two sources, triester degradation and direct inputs. Land application of sludge to US soils was estimated to result in annual mass inputs of 12,400-14,900?kg/year of OP triesters and 663-796?kg/year of OP diesters. A hazard assessment was performed for 14 OPEs found in sludge, which suggested a low level of risk at the current land application practices of sludge.
Project description:Five parabens used as preservatives in pharmaceuticals and personal care products (PPCPs) were measured in sewage sludges collected at 14 U.S. wastewater treatment plants (WWTPs) located in nine states. Detected concentration ranges (ng/g, dry weight) and frequencies were as follows: methyl paraben (15.9 to 203.0; 100%), propyl paraben (0.5 to 7.7; 100%), ethyl paraben (<0.6 to 2.6; 63%), butyl paraben (<0.4 to 4.3; 42%) and benzyl paraben (<0.4 to 3.3; 26%). The estrogenicity inherent to the sum of parabens detected in sewage sludge (ranging from 10.1 to 500.1pg/kg 17?-estradiol equivalents) was insignificant when compared to the 106-times higher value calculated for natural estrogens reported in the literature to occur in sewage sludge. Temporal monitoring at one WWTP provided insights into temporal and seasonal variations in paraben concentrations. This is the first report on the occurrence of five parabens in sewage sludges from across the U.S., and internationally, the first on temporal variations of paraben levels in sewage sludge. Study results will help to inform the risk assessment of sewage sludge destined for land application (biosolids).
Project description:To understand microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and the effects of environmental factors on their structure, 12 activated sludge samples were collected from four WWTPs in Beijing. GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes. The results showed that, for each gene category, such as egl, amyA, nir, ppx, dsrA sox and benAB, there were a number of microorganisms shared by all 12 samples, suggestive of the presence of a core microbial community in the activated sludge of four WWTPs. Variance partitioning analyses (VPA) showed that a total of 53% of microbial community variation can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively. This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs. Four full-scale wastewater treatment systems located in Beijing were investigated. Triplicate samples were collected in each site.
Project description:To simultaneously quantify and profile the complex mixture of short-, median-, and long-chain CPs (SCCPs, MCCPs, and LCCPs) in Australian sewage sludge, we applied and further validated a recently developed novel instrumental technique, using quadrupole time-of-flight high resolution mass spectrometry running in the negative atmospheric pressure chemical ionization mode (APCI-qTOF-HRMS). Without using an analytical column the cleaned extracts were directly injected into the qTOF-HRMS followed by quantification of the CPs by a mathematical algorithm. The recoveries of the four SCCP, MCCP and LCCP-spiked sewage sludge samples ranged from 86 to 123%. This APCI-qTOF-HRMS method is a fast and promising technique for routinely measuring SCCPs, MCCPs, and LCCPs in sewage sludge. Australian sewage sludge was dominated by MCCPs with concentrations ranging from 542 to 3645 ng/g dry weight (dw). Lower SCCPs concentrations (<57-1421 ng/g dw) were detected in the Australian sewage sludge, which were comparable with the LCCPs concentrations (116-960 ng/g dw). This is the first time that CPs were reported in Australian sewage sludge. The results of this study gives a first impression on the distribution of the SCCPs, MCCPs, and LCCPs in Australia wastewater treatment plants (WWTPs).
Project description:Mycobacterium often presents as an abundant bacterial genus in activated sludge in many wastewater treatment plants (WWTPs), but the species-level taxonomy and functions remain poorly understood. In this study, we profiled the mycobacterial communities in eleven WWTPs from five countries by pyrosequencing the rpoB amplicons and searching against a customized database of mycobacterial rpoB sequences. Results indicated that major mycobacterial species were related to M. brumae, M. crocinum, M. sphagni, etc., most of which belong to poorly characterized rapidly-growing group. A few opportunistic pathogenic species were detected, suggesting the potential risk of mycobacteria in WWTPs. Genomic analysis of four isolates from activated sludge indicated these genomes contained genes of degradations of alkane, aromatics, steroids and a variety of cytochrome P450 families. Additionally, a few key genes responsible for cholesterol degradation were detected in a full-scale activated sludge metatranscriptomic dataset reported previously and taxonomically assigned to mycobacteria. Evidence showed that all isolates can degrade cholesterol, a major composition of sewage. Relative abundance of mycobacteria in activated sludge was enriched by 4.7 folds after adding cholesterol into the influent for one week. Our results provided the insights into mycobacterial species and functions in WWTPs.