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Biodegradation of nonylphenols, determination of degradation products and detection of responsible microorganisms using molecular techniques
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Date
2015
Author
Kara Murdoch, Fadime
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Nonylphenol(poly)ethoxylates (NPnEO) have received special attention during the last decades due to their toxic and endocrine-disrupting effects for many organisms. They have limited degradation in wastewater treatment plants especially in activated sludge units. Since they accumulate in sludge, understanding of their fate during sludge treatment is important. With this motivation, this research aimed to monitor the degradation of nonylphenol diethoxylate (NP2EO, as a parent compound) into its degradation products, nonylphenol monoethoxylate (NP1EO) and nonylphenol (NP), in lab-scale semi-continuous anaerobic digesters. Determination and quantification of the degradation products were carried out with gas chromatography-mass spectrometry (GC/MS). Fluorescence in situ hybridization (FISH) and quantitative PCR (qPCR) were used to determine the abundance and composition of four sub-groups of Proteobacteria and acetoclastic methanogens in the total microbial community of anaerobic digesters in the presence and absence of NP2EO. Moreover, enrichment studies were performed in order to isolate diverse bacterial strains able to use branched NP as the sole carbon and energy source. Results showed that NP2EO degraded slowly under anaerobic conditions and NP accumulated as a final product in digesters. Digester performance monitored by solids reduction, chemical oxygen demand (COD) removal and methane production showed no deterioration due to NP2EO spike. Beta- and Gammaproteobacteria constituted the predominant sub-groups of Proteobacteria within the NP2EOspiked sludge community of anaerobic digesters according to FISH and qPCR results. The dominant proliferation of the Methanosaeta (62.5-77%) member of acetoclastic methanogens was determined in the all operated anaerobic digesters.
Subject Keywords
Biodegradation.
,
Hybridization.
,
Anaerobiosis.
,
Fluorescence.
,
Phenols.
URI
http://etd.lib.metu.edu.tr/upload/12619012/index.pdf
https://hdl.handle.net/11511/25193
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Graduate School of Natural and Applied Sciences, Thesis
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F. Kara Murdoch, “Biodegradation of nonylphenols, determination of degradation products and detection of responsible microorganisms using molecular techniques,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.
