Biological treatment of n-hexane and methanol in trickle bed air biofilters under acidic conditions

Zehraoui, Abderrahman; Hassan, Ashraf Aly; Sorial, George A.

doi:10.1016/j.bej.2013.06.001

Cited by 40 publications

(17 citation statements)

References 28 publications

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“…S: stagnation, FS: flow switching. efficiencies and greater elimination capacities as compared to TBABs C and D. These findings were in concordance with our previous published works where TBABs running under acidic conditions, using sodium formate as a nutrient buffer, had always higher performances compare to the TBABs running under neutral pH using sodium bicarbonate as a buffer (Aly Hassan and Sorial, 2010b;Zehraoui et al, 2012Zehraoui et al, , 2013Zehraoui et al, 2014). On the other hand, even though TBABs C and D, fed by nutrient buffer at pH 7, did not achieve results comparable with those of TBABs A and B, the TBABs supported n-hexane LRs of 36.3 g m À3 hr À1 to achieve an EC of 23.4 g m À3 hr À1 .…”

Section: Performance Of Tbabs C and Dsupporting

confidence: 82%

“…While stagnation is a complete closure of air, VOCs and buffer nutrient flow for 2 days per week. All these techniques were previously applied in the biofiltration of hydrophilic and hydrophobic VOCs and were proven to be very effective in biomass control (Aly Hassan and Sorial, 2010a;Kim et al, 2005b;Zehraoui et al, 2012Zehraoui et al, , 2013.…”

Section: Trickling Biofiltersmentioning

confidence: 99%

“…The results were varied according to the biofilter or reactor used, support medium, and mode of operation. For instance, Zehraoui et al (2013) obtained a very high removal efficiency (RE) of 95% with high stability for treating n-hexane after a period of use with methanol at a loading rate (LR) of 13.2 g m À3 hr À1 , which corresponds to an elimination capacity (EC) of 12.5 gm À3 hr À1 . Previously, Aly Hassan and Sorial (2010a) obtained a 90% in RE at a LR of 47.7 g m À3 hr À1 for a TBAB operating at pH 4.…”

Section: Introductionmentioning

confidence: 99%

“…It is commonly used in a broad range of industrial applications, which eventually lead to its emission from different sources such as printing and publishing, polymer and humanmade fiber, pulp and paper, and organic chemical industries (Zehraoui et al, 2012(Zehraoui et al, , 2013Zehraoui et al, 2014). The reported literature reviews were on behalf of its biodegradation in traditional biofilters, TBABs, or in new technologies such as the silicone oil-amended biofilter, two liquid phase biofiltration, and two-phase partitioning bioreactor.…”

Section: Introductionmentioning

confidence: 99%

“…Many processes were tested for addressing the bioavailability of hydrophobic contaminants. One is the introduction of surfactants (Aly Hassan and Sorial, 2008;Woertz and Kinney, 2004), providing favorable conditions for fungi (Aly Hassan and Sorial, 2008;Arriaga and Revah, 2005a;Hernández-Meléndez et al, 2008;Spigno and De Faveri, 2005;Van Groenestijn et al, 2001); others include mixture of n-hexane with other less hydrophobic compound such as benzene (Aly Hassan and Sorial, 2010a), introduction of more hydrophilic contaminants in mixture with n-hexane, such methanol (Zehraoui et al, 2012(Zehraoui et al, , 2013, and most recently the alternate use of methanol with n-hexane (Zehraoui et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Treatment of hydrophobic VOCs in trickling bed air biofilter: Emphasis on long-term effect of initial alternate use of hydrophilic VOCs and microbial species evolution

Zehraoui

Sorial

2014

Journal of the Air & Waste Management Association

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The main research objective of this study is to enhance the removal of recalcitrant compounds that are not readily bioavailable due to limiting mass transfer rate between the liquid and gas phases. Four trickle-bed air biofilters (TBABs), loaded with pelletized diatomaceous earth support media, were run at an empty bed residence time (EBRT) of 120 sec. After an acclimation period at constant loading rate (LR) of n-hexane (13.2 g m À3 hr À1 ) and intermittent feeding of methanol, n-hexane influent LR was then increased in step-wise fashion to 47.7 g m À3 hr À1 for biofilters receiving acidic nutrients (pH 4), and to 36.3 g m À3 hr À1 for biofilters receiving nutrient at pH 7. The results have shown that for TBABs receiving nutrient at pH 4, greater elimination capacities were obtained as compared to TBABs working at pH 7. n-Hexane removal efficiency of more than 84% at LR up to 47.7 g m À3 hr À1 was obtained for pH 4 nutrient-fed biofilters, while for biofilters with nutrients fed at pH 7, the removal efficiency did not exceed 64% for n-hexane LR of 36.3 g m À3 hr À1 . The microbial analysis revealed that no fungal community was detected in TBABs run at neutral pH. The fungi communities that were initially acclimating TBABs run at pH 4, namely, Aspergillus niger and Fusarium solani, were not detected at the end of the experiment, while Gibberella moniliformis (Fusarium verticillioides) genus became the dominant species. Gibberella moniliformis (Fusarium verticillioides) was present along all the biofilter media and sustained very high nhexane elimination at steady-state condition.Implications: With growing apprehension about sustainability and environmental protection, with limited resources available, and with the passage of the 1990 Amendments to the Clean Air Act, there is more need for using air pollution control techniques that are sound economically and proven environmentally friendly. Biofiltration systems, namely, trickle-bed air biofilters, were for decades recognized as efficient in treating air pollutants. Thus, the application of this technique over a wide industrial spectrum would certainly contribute to reduction of hazardous gas emissions.

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Section: Performance Of Tbabs C and Dsupporting

confidence: 82%

Section: Trickling Biofiltersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Treatment of hydrophobic VOCs in trickling bed air biofilter: Emphasis on long-term effect of initial alternate use of hydrophilic VOCs and microbial species evolution

Zehraoui

Sorial

2014

Journal of the Air & Waste Management Association

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Influence of Nonionic Surfactants on Fungal and Bacterial Degradation of Hexane

Wei

Hessler

Sorial

et al. 2016

CLEAN Soil Air Water

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Batch solubility and microcosm studies were conducted to examine the role of nonionic surfactants (Brij 30, Brij 35, Triton X-100, and Tween 80) on fungal and bacterial degradation of hexane, a model volatile organic compound with a high Henry's law constant. The apparent solubility of gas phase hexane was not observed as a linear correlation in respect to surfactant concentration due to the insufficient mass transfer at the gas-liquid interface. The hexane partitioning to micellar phase was related to the unique structure of surfactants with different lengths of hydrophobic alkyl or hydrophilic polyoxyethylene chains. Microcosm test results revealed that most tested surfactants below critical micelle concentration (CMC) improved the fungal and bacterial growth, but surfactants at high concentration (5 CMC) adversely affected biodegradation kinetics. The observed low hexane removal was possibly attributed to the toxicity of surfactants at elevated concentration, the preferential utilization of a surfactant as substrate, and the partitioning of hexane into micellar phase. The results from this study suggest that low concentrations of Brij 30 and Tween 80 are favorable to enhance both the solubility and bioavailability of hexane with fungi as working consortium, while Brij 30 and Triton X-100 below their CMC hold promising potential for bacterial degradation of hexane without having significant biodegradation of the surfactant.

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