Document Detail

Fate and effects of triclosan in activated sludge.
MedLine Citation:
PMID:  12109731     Owner:  NLM     Status:  MEDLINE    
Triclosan (TCS; 5-chloro-2-[2,4-dichloro-phenoxy]-phenol) is a widely used antimicrobial agent. To understand its fate during sewage treatment, the biodegradation and removal of TCS were determined in activated sludge. In addition, the effects of TCS on treatment processes were assessed. Fate was determined by examining the biodegradation and removal of TCS radiolabeled with 14C in the 2,4-dichlorphenoxy ring in laboratory batch mineralization experiments and bench-top continuous activated-sludge (CAS) systems. In batch experiments with unacclimated sludge, TCS was mineralized to 14CO2, but the total yield varied as a function of test concentration. Systems that were redosed with TCS exhibited more extensive and faster mineralization, indicating that adaptation was a critical factor determining the rate and extent of biodegradation. In a CAS study in which the influent level of TCS was incrementally increased from 40 microg/L to 2,000 microg/L, removal of the parent compound exceeded 98.5% and removal of total radioactivity (parent and metabolites) exceeded 85%. Between 1.5 and 4.5% of TCS in the influent was sorbed to the wasted solids, whereas >94% underwent primary biodegradation and 81 to 92% was mineralized to CO2 or incorporated in biomass. Increasing levels of TCS in the influent had no major adverse effects on any wastewater treatment process, including chemical oxygen demand, biological oxygen demand, and ammonia removal. In a subsequent experiment, a CAS system, acclimated to TCS at 35 microg/L, received two separate 4-h shock loads of 750 microg/L TCS. Neither removal of TCS nor treatment processes exhibited major adverse effects. An additional CAS study was conducted to examine the removal of a low level (10 microg/L) of TCS. Removal of parent equaled 94.7%, and biodegradation remained the dominant removal mechanism. A subsequent series of CAS experiments examined removal at four influent concentrations (7.5, 11, 20, and 50 microg/L) of TCS and demonstrated that removal of parent ranged from 98.2 to 99.3% and was independent of concentration. Although TCS removal across all experiments appeared unrelated to influent concentration, removal was significantly correlated (r2 = 0.87) with chemical oxygen demand removal, indicating that TCS removal was related to overall treatment efficiency of specific CAS units. In conclusion, the experiments show that TCS is extensively biodegraded and removed in activated-sludge systems and is unlikely to upset sewage treatment processes at levels expected in household and manufacturing wastewaters.
Thomas W Federle; Sandra K Kaiser; Barbara A Nuck
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Environmental toxicology and chemistry / SETAC     Volume:  21     ISSN:  0730-7268     ISO Abbreviation:  Environ. Toxicol. Chem.     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-07-11     Completed Date:  2003-01-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8308958     Medline TA:  Environ Toxicol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1330-7     Citation Subset:  IM    
The Procter & Gamble Company, Cincinnati, Ohio 45253-8707, USA.
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MeSH Terms
Anti-Infective Agents, Local / analysis,  chemistry*
Biodegradation, Environmental
Carbon Radioisotopes
Chromatography, High Pressure Liquid
Sewage / chemistry*,  microbiology
Triclosan / analysis,  chemistry*
Water Pollutants, Chemical / analysis*
Water Purification / methods
Reg. No./Substance:
0/Anti-Infective Agents, Local; 0/Carbon Radioisotopes; 0/Sewage; 0/Water Pollutants, Chemical; 3380-34-5/Triclosan

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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