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Biodegradation of octylphenol polyethoxylates by denitrification
A Jiménez-González1, S Siles-Alvarado, O Monroy
1Departamento de Biotecnología, Universidad Autónoma Metropolitana, Apdo. Postal 55-535, C.P. 09340 Iztapalapa DF México.
Summary
Octylphenol ethoxylates (OPEOs) biodegradation in denitrifying sludge revealed complex degradation pathways. The study identified simultaneous routes involving alkyl chain cleavage and hydrophilic/hydrophobic attacks, leading to complete OPEO transformation.
Area of Science:
- Environmental Science
- Environmental Chemistry
- Microbiology
Background:
- Octylphenol ethoxylates (OPEOs) are nonionic surfactants with environmental persistence.
- Understanding OPEO biodegradation pathways is crucial for wastewater treatment.
- Denitrification processes offer potential for degrading recalcitrant organic pollutants.
Purpose of the Study:
- To elucidate the biodegradation routes of OPEOs under denitrifying conditions.
- To identify intermediate metabolites during OPEO degradation.
- To investigate the mechanisms of OPEO breakdown in an upflow anoxic sludge blanket (UASB) reactor.
Main Methods:
- Acclimation of anaerobic sludge to increasing OPEO concentrations.
- Operation of an upflow anoxic sludge blanket (UASB) reactor.
- High-Performance Liquid Chromatography (HPLC) and Gas Chromatography-Mass Spectrometry (GC-MS) for metabolite identification.
Main Results:
- Complete transformation of OPEOs was achieved with 70% COD removal.
- Octylphenol (OP) was transiently formed and subsequently disappeared.
- Novel intermediates, propylphenol triethoxylate (PPEO3) and heptylphenol diethoxylated (HPEO2), were identified, indicating simultaneous degradation routes.
Conclusions:
- OPEO biodegradation under denitrification involves multiple simultaneous pathways.
- Degradation involves cleavage of the alkyl chain and attack on both hydrophilic and hydrophobic moieties.
- These findings provide insights into the microbial degradation of OPEOs in anaerobic environments.