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UM E-Theses Collection (澳門大學電子學位論文庫)

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Title

Biodegradation of environmental endocrine disruptor di-2-ethylhexyl phthalate (DEHP) in aqueous by an indigenous isolate Acinetobacter sp

English Abstract

Di(2-ethylhexyl) phthalate (DEHP) has been widely used as a plasticizer for industrial, domestic, and medical plastic products and is considered as one of the endocrine disruptors present in the environment. A bacterial strain capable of degrading DEHP from the artificially contaminated water (with over 90% removal within 5 days of incubation) was isolated from the activated sludge obtained from a regional wastewater treatment plant in Macau Special Administrative Region, China. The isolate was identified as Acinetobacter sp. SN13 by the 16S rRNA gene sequence analysis. Two major environmental factors, temperature (35C) and pH (6-9), were further optimized to enhance the biodegradation efficiency for DEHP. The growth kinetics of this indigenous isolate on DEHP followed the inhibition model, with the maximum degradation rate, the half saturation constant, and the inhibition constant of 124.8 mg l-1 day-1 , 272.3 mg l-1 , and 720.5 mg l-1 , respectively. The inhibition model for the specific growth rate was also simulated using Matlab software, and the respective maximum specific growth rate, half saturation constant, and inhibition constant were 0.1192 day-1 , 137.6 mg l-1 , and 850.3 mg l-1 . The highest degradation rate was achieved when the initial concentration of DEHP was 400 mg l-1 . The effect V of the micro elements (Fe3+ and Mn2+) at different concentrations levels (100, 500, 1000 µg l-1 ) on DEHP degradation was further investigated. The biodegradation performance of the isolate was improved as the concentration of Fe3+ presented in water increased from 100 to 1000 µg l-1 while higher concentrations of Mn2+ (500, 1000 µg l-1 ) inhibited the biodegradation in some extent. The respective DEHP degradation pathway for the isolate is also proposed by the identification of the following intermediates: mono-(2-ethylhexyl) phthalate (MEHP), phthalic acid (PA), protocatechuate, β-carboxy-cis,cis-muconic acid, and 3-katoadipate.

Issue date

2016.

Author

Xu, Jia Ming,

Faculty

Faculty of Science and Technology

Department

Department of Civil and Environmental Engineering

Degree

M.Sc.

Subject

Biodegradation

Endocrine disrupting chemicals

Supervisor

Shim, Hojae

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Location
1/F Zone C
Library URL
991001910729706306