Limits...
Transformation products and human metabolites of triclocarban and triclosan in sewage sludge across the United States.

Pycke BF, Roll IB, Brownawell BJ, Kinney CA, Furlong ET, Kolpin DW, Halden RU - Environ. Sci. Technol. (2014)

Bottom Line: 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.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).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.

View Article: PubMed Central - PubMed

Affiliation: Center for Environmental Security, Biodesign Institute, Security and Defense Systems Initiative, Arizona State University , 781 East Terrace Road, Tempe, Arizona 85287, 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.

Show MeSH

Related in: MedlinePlus

Effect of different conventionalsludge treatment processes onthe concentrations of TCC, its microbial and human metabolites, andproduction byproducts along with those for TCS and MeTCS in sewagesludge and biosolids from selected WWTPs. #: number of sampled WWTP.*: p < 0.01; **: p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4215897&req=5

fig4: Effect of different conventionalsludge treatment processes onthe concentrations of TCC, its microbial and human metabolites, andproduction byproducts along with those for TCS and MeTCS in sewagesludge and biosolids from selected WWTPs. #: number of sampled WWTP.*: p < 0.01; **: p < 0.05.

Mentions: WhereasTCS methylationis commonly observed in aerobic environments,47 dechlorination of TCC, if occurring, is likely located in an oxygen-limitingmilieu, assuming the process and microbial ecology are similar tothe reductive dechlorination of trichloroethene. Hence, the anaerobicdigester is a likely environment for dechlorination to occur in aconventional WWTP, due to the redox conditions required for biogasproduction. For this reason, contaminant levels were determined insludge sampled before and after anaerobic digestion from two siteswith medium DCC/TCC ratios (nos. 15 and 16). However, data from thesetwo plants revealed that anaerobic digestion of the sludge resultedin a significant accumulation of TCC, TCS, and their transformationproducts (α = 0.01 and α = 0.05) (Figure 4). These findings suggested that these parent compounds aremore persistent relative to the organic matter that is to be gasifiedand mineralized during the digestion process. In a third WWTP (no.6), anaerobic digested sludge was dewatered; yet, the dewatering processresulted in only minor removal for TCC and 3-Cl′-TCC, whileno significant changes were observed for the other carbanilides (Figure 4C). In a fourth WWTP (no. 14) with a high DCC/TCCratio (Figure 3), significant removal was observedfor nearly all carbanilides (Figure 4D; α= 0.01) after heat treating the digested sludge. Comparison of theoccurrences of the transformation products before and after the treatment,indicated good removal for MCC (85%) compared to 49% for TCC. Conversely,the manufacturing byproduct 3′-Cl-TCC was not removed nor didit accumulate significantly after heat treatment of the digested sludgeat plant no. 14 (Figure 4D). Overall, treatmentof the sludge resulted in an increase in the DCC/TCC ratio for theWWTP. The observed increases were for heat drying of AD sludge: from0.28 to 0.45 (p < 0.01; α = 0.01), dewateringof AD sludge: from 0.10 to 0.12 (p = 0.208; α= 0.01), and AD of untreated sludge at two plants: from 0.01 to 0.04(p < 0.01; α = 0.01) and from 0.010 to 0.014(p < 0.01; α = 0.01).


Transformation products and human metabolites of triclocarban and triclosan in sewage sludge across the United States.

Pycke BF, Roll IB, Brownawell BJ, Kinney CA, Furlong ET, Kolpin DW, Halden RU - Environ. Sci. Technol. (2014)

Effect of different conventionalsludge treatment processes onthe concentrations of TCC, its microbial and human metabolites, andproduction byproducts along with those for TCS and MeTCS in sewagesludge and biosolids from selected WWTPs. #: number of sampled WWTP.*: p < 0.01; **: p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215897&req=5

fig4: Effect of different conventionalsludge treatment processes onthe concentrations of TCC, its microbial and human metabolites, andproduction byproducts along with those for TCS and MeTCS in sewagesludge and biosolids from selected WWTPs. #: number of sampled WWTP.*: p < 0.01; **: p < 0.05.
Mentions: WhereasTCS methylationis commonly observed in aerobic environments,47 dechlorination of TCC, if occurring, is likely located in an oxygen-limitingmilieu, assuming the process and microbial ecology are similar tothe reductive dechlorination of trichloroethene. Hence, the anaerobicdigester is a likely environment for dechlorination to occur in aconventional WWTP, due to the redox conditions required for biogasproduction. For this reason, contaminant levels were determined insludge sampled before and after anaerobic digestion from two siteswith medium DCC/TCC ratios (nos. 15 and 16). However, data from thesetwo plants revealed that anaerobic digestion of the sludge resultedin a significant accumulation of TCC, TCS, and their transformationproducts (α = 0.01 and α = 0.05) (Figure 4). These findings suggested that these parent compounds aremore persistent relative to the organic matter that is to be gasifiedand mineralized during the digestion process. In a third WWTP (no.6), anaerobic digested sludge was dewatered; yet, the dewatering processresulted in only minor removal for TCC and 3-Cl′-TCC, whileno significant changes were observed for the other carbanilides (Figure 4C). In a fourth WWTP (no. 14) with a high DCC/TCCratio (Figure 3), significant removal was observedfor nearly all carbanilides (Figure 4D; α= 0.01) after heat treating the digested sludge. Comparison of theoccurrences of the transformation products before and after the treatment,indicated good removal for MCC (85%) compared to 49% for TCC. Conversely,the manufacturing byproduct 3′-Cl-TCC was not removed nor didit accumulate significantly after heat treatment of the digested sludgeat plant no. 14 (Figure 4D). Overall, treatmentof the sludge resulted in an increase in the DCC/TCC ratio for theWWTP. The observed increases were for heat drying of AD sludge: from0.28 to 0.45 (p < 0.01; α = 0.01), dewateringof AD sludge: from 0.10 to 0.12 (p = 0.208; α= 0.01), and AD of untreated sludge at two plants: from 0.01 to 0.04(p < 0.01; α = 0.01) and from 0.010 to 0.014(p < 0.01; α = 0.01).

Bottom Line: 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.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).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.

View Article: PubMed Central - PubMed

Affiliation: Center for Environmental Security, Biodesign Institute, Security and Defense Systems Initiative, Arizona State University , 781 East Terrace Road, Tempe, Arizona 85287, 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.

Show MeSH
Related in: MedlinePlus