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ENHANCED BIOLOGICAL OXIDATION OF HYDROPHOBIC COMPOUNDS UNDER DYNAMIC LOAD IN A TRICKLE BED AIR BIOFILTER

Zehraoui, Abderrahman
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384849490

Abstract Details

2013, PhD, University of Cincinnati, Engineering and Applied Science: Environmental Engineering.
Biofiltration systems demonstrated to very effective in removal of volatile organic compounds (VOCs) from air operating under dynamic loading rates and stressed conditions. More interestingly, Trickle Bed Air Biofilters (TBABs) offer more optimal and controllable operations which result in low maintenance costs over traditional biofilters. Furthermore, due to their higher removal efficiency, consistent performance, and harmless by-products generated they became an attractive option for controlling VOCs emissions from various industrial processes. Yet, biofiltration systems face a number of challenges to compete new proposed techniques such as two-phase bioreactors and oil emended biofilters. Characteristically, hydrophobic compounds, with higher Henry's law constant, present a great challenge for these systems as they are not soluble in water. Limited bioavailability of these VOCs could trigger mass transfer to be rate limiting from gas to liquid phase and hence negatively affecting biofilters performances. Moreover, as biofilters are biologically dependent systems, the exact characterization of the microbial community structures within the active biomass need to be developed in order to get deep insight of the species involved to make the biofiltration technique more efficient, reliable, and oriented either to specific VOCs as well as to be flexible in handling a variety of VOCs. Most importantly, air emissions are always mixture of different type of gases rather than a sole VOC. Hence, inhibitory effect among VOCs could hinder the widespread application of these systems in facilities where off gases are a combination of hydrophilic and hydrophobic VOCs. Finally, variability in waste gases flow and fluctuations in their concentrations limit the treatment efficiency of the biofiltration systems. In this regard, the current study investigated several techniques to effectively biodegrade hydrophobic contaminants. Responding to this aim, the solutions presented were: 1) enhancement of hydrophobic VOCs (n-hexane) bioavailability by introducing highly biodegradable and oxygenated VOC (methanol), 2) alternate presence and absence use of hydrophilic VOC, 3) initial acclimation period of biofilters with hydrophilic VOC, and 4) proposition of an integrated system consisting of buffering capacity of a two-bed cyclic adsorption/desorption unit followed by a TBAB. The TBABs performances obtained were well corroborated with the 16S and 18S rDNA PCR and sequencing analyses performed. These results also confirmed the supremacy of fungi over bacteria, the advantage of alternating methanol use, as well as the benefit of an initial acclimation period of TBABs by methanol for maintaining high removal efficiency and stable performance that was largely contested as a negative point for treating hydrophobic VOCs in TBABs. Most importantly, the cyclic beds of the integrated unit buffered the fluctuating influent VOCs loads and the followed biofilter had all the time a continuous and stable flow which helped in achieving high VOCs removal. On the contrary, the control biofilter suffered from the frequent change in loading rates and could not resist the alteration in the influent VOCs loads that negatively influenced their uptake for metabolism by the microorganisms.
George Sorial, Ph.D. (Committee Chair)
Ashraf Aly Hassan, Ph.D. (Committee Member)
E Sahle-Demessie, Ph.D. (Committee Member)
Makram Suidan, Ph.D. (Committee Member)
David Wendell, Ph.D. (Committee Member)
263 p.
Environmental Engineering
Biofiltration; Trickle Bed Air Biofilter; Mixture of Hydrophilic and Hydrophobic VOCs; Fungi vs Bacteria; adsorption desorption bed; Environmental Samples Sequencing

Recommended Citations

Citations

  • Zehraoui, A. (2013). ENHANCED BIOLOGICAL OXIDATION OF HYDROPHOBIC COMPOUNDS UNDER DYNAMIC LOAD IN A TRICKLE BED AIR BIOFILTER [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384849490

    APA Style (7th edition)

  • Zehraoui, Abderrahman. ENHANCED BIOLOGICAL OXIDATION OF HYDROPHOBIC COMPOUNDS UNDER DYNAMIC LOAD IN A TRICKLE BED AIR BIOFILTER. 2013. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384849490.

    MLA Style (8th edition)

  • Zehraoui, Abderrahman. "ENHANCED BIOLOGICAL OXIDATION OF HYDROPHOBIC COMPOUNDS UNDER DYNAMIC LOAD IN A TRICKLE BED AIR BIOFILTER." Doctoral dissertation, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384849490

    Chicago Manual of Style (17th edition)

ucin1384849490
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© 2013, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.