Anaerobic degradation of alcohol ethoxylates and polyethylene glycols in marine sediments

• Published in: The Science of the total environment Vol. 544; pp. 118 - 124
• Main Authors: Traverso-Soto, Juan M., Rojas-Ojeda, Patricia, Sanz, José Luis, González-Mazo, Eduardo, Lara-Martín, Pablo A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.02.2016
• Subjects: Alcohol polyethoxylates; Anaerobiosis; Biodegradation; Biodegradation, Environmental; Freshwater; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Polyethylene glycols; Polyethylene Glycols - analysis; Polyethylene Glycols - metabolism; Seawater - chemistry; Seawater - microbiology; Sediments; Surface-Active Agents - analysis; Surface-Active Agents - metabolism; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; Biodegradation; Alcohol polyethoxylates; Sediments; Polyethylene glycols
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.11.140

This research is focused on alcohol polyethoxylates (AEOs), nonionic surfactants used in a wide variety of products such as household cleaners and detergents. Our main objective in this work was to study the anaerobic degradation of these compounds and their main aerobic degradation products and precursors (polyethylene glycols, PEGs, which are also used for many other applications) in marine sediments, providing the first data available on this topic. First, we observed that average AEO sediment-water partition coefficients (Kd) increased towards those homologs having longer alkyl chains (from 257L/kg for C12 to 5772L/kg for C18), which were less susceptible to undergo biodegradation. Overall, AEO and PEG removal percentages reached up to 99.7 and 93%, respectively, after 169days of incubation using anaerobic conditions in sediments ([O2]=0ppm, Eh=−170 to −380mV and T=30°C). Average half-life was estimated to be in a range from 10 to 15days for AEO homologs (C12AEO8–C18AEO8), and 18days for PEGEO8. Methanogenic activity proved to be intense during the experiment, confirming the occurrence of anaerobic conditions. This is the first study showing that AEOs and PEGs can be degraded in absence of oxygen in marine sediments, so this new information should be taken into account for future environmental risk assessments on these chemicals. [Display omitted] •Anoxic degradation of AEOs/PEG in marine sediments were studied for the first time.•Methanogenic activity is a good indicator of AEOs and PEG degradation.•Removal of AEOs and PEG reached up to 99.7 and 93%, respectively (169days, 30°C).•The major fraction on the non-degraded AEOs corresponded to C16 and C18 homologs.