Screening for biodegradation, characterization, and optimization of petroleum hydrocarbons (PHCs) extracted from refinery wastewater to highy valuable transformed compounds /
Muna Ibrahim A. Eldurssi
- xvii, 157 pages : illustrations (some color) ; 30 cm. + 1 CD ROM
Faculty of Industrial Sciences and Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2021
Includes bibliographical references
Crude oil refining expends large water volumes, and the refinery wastewater is often contaminated with petroleum hydrocarbons (PHCs). Most of the reported field studies and reviews focused mainly on the assessment of bioremediation technology. Therefore, this research investigates the biodegradation of PHCs extracted from refinery wastewater through a liquid- liquid extraction (LLE) method, to produce new value-added compounds in a short time and obtain a high rate of PHCs degradation. The compounds were analyzed by gas chromatography-mass spectroscopy (GC-MS) during various incubation periods. Then, the process parameters were optimized through response surface methodology (RSM). Two out of 13 bacterial isolates, KRD2 and KRA4 were selected from PHCs contaminated water samples collected from Kuantan River. On the other hand, dichloromethane was used to extract PHCs from refinery wastewater collected from a petroleum-based company. The functional groups were identified by FT-IR, and the change in surface morphology of the bacterial isolates before and after PHCs degradation was examined by FESEM. The FESEM confirmed the successful biodegradation of PHCs, within 5 days. Specifically, it was observed that KRD2, KRA4 and KRD2A4 isolates degraded all 13 initially extracted PHCs compounds in about 5 days. KRD2 degraded all compounds except C13BD, KRA4 degraded all compounds except C9BD, while KRD2A4 degraded all compounds except C1BD, C5BD, C6BD, C7BD and C13BD. On the other hand, a different number of compounds were produced as secondary metabolites by KRD2, KRA4 and KRD2A4 at varying peak area percentages. After 10 days, only 6, 8 and 11 compounds were successfully degraded by the isolates, respectively whereas all the initial compounds were fully degraded after 15days, except C11BD. All metabolites were produced by all isolates except C10PAD, C3PAD, and C14PAD by KRD2, KRA4, and KRD2A4, respectively at peak areas 11.16, 52.31, and 4.18%. Significantly, GC-MS analysis revealed that PHCs were successfully biodegraded into new compounds such as Nmethyl-N'-nitro-N-nitroso-Guanidine, C2H5N5O3, with a percentage of (74.09%) after 10 days. In addition, the percentage of main compounds is (100) % after 5 days. This is due to their significantly high peak. Notably, the compounds produced have potential industrial and medical applications compared to the control. The alignment (PCR Analysis) revealed that KRD2 and KRA4 isolates belong to the genus Mycobacterium confluentis and Chryseobacterium gambrini, respectively.Comparison and optimization of the process parameters involved in the biodegradation of PHCs using Mycobacteria confluentis was performed through the ANOVA test and a second-order polynomial model. The capability of Mycobacteria confluentis to degrade the PHCs was found to be maximum at pH 9.4, the temperature of 33.9℃, PHCs concentration of 55.82 μL/mL, and incubation period of 5 days. Significantly, PHCs degradation reached 92.99 %. This finding showed that this new isolate of Mycobacteria confluentis can use phenanthrene and pyrene as sole carbon sources. Hence, this research presents the potential of using local aerobic bacterial isolates for as an alternative solution to remove PHCs from refinery wastewater and produce new compounds have potential industrial and medical applications in a short time.
THE0009237(Local)
Faculty of Industrial Sciences and Technology--Dissertations