Removal of p-xylene from an air stream in a hybrid biofilter

School of Environmental and Biological Science and Technology, Dalian University of Technology No. 2, Linggong Road, Dalian, Liaoning Province 116023, PR China.
Journal of Hazardous Materials (Impact Factor: 4.53). 09/2006; 136(2):288-95. DOI: 10.1016/j.jhazmat.2005.12.017
Source: PubMed


Biofiltration of an air stream containing p-xylene has been studied in a laboratory hybrid biofilter packed with a mixture of mature pig compost, forest soil and the packing material which was made of polyethylene (PE) and used in the moving bed biological reactor (MBBR) in wastewater treatment. Three flow rates, 9.17, 19.87 and 40.66 m(3)m(-2)h(-1), were investigated for p-xylene inlet concentration ranging from 0.1 to 3.3 g m(-3). A high elimination capacity of 80 g m(-3)h(-1) corresponding to removal efficiency of 96% was obtained at a flow rate of 9.17 m(3)m(-2)h(-1) (empty bed residence time of 132 s). At a flow rate of 40.66 m(3)m(-2)h(-1) (empty bed residence time of 30s), the maximum elimination capacity for p-xylene was 40 g m(-3)h(-1) and removal efficiencies were in the range of 47-100%. The production of carbon dioxide (P(CO(2))) is proportional to elimination capacity (EC) and the linear relation was formulated as P(CO(2))=1.65EC+15.58. Stable pH values ranging from 6.3 to 7.6 and low pressure drop values less than 0.2 cm H(2)O (19.6 Pa) of packing media in compost-based biofilter of hybrid biofilter were observed, which avoided acidification and compaction of packing media and sustained the activity of microorganism populations.

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    • "While organic materials are shown to be low-priced and suitable to potentially release inorganic nutrients and keep the water content at optimal levels for microorganisms, inorganic materials generally offer higher contact surfaces and durability [7]. Some tested hybrid materials for air pollutants removal by biofiltration have shown faster startups and more stable nitrification capacities than organic packings [8] as well as low pressure drop, acidification and compaction along biofilter operation [9]. Still, removal of high loads of toluene entails important operational difficulties. "
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    ABSTRACT: Biomass accumulation was studied in a biofilter packed with an organic/inorganic, hybrid packing material made of clay pellets plus clay pellets covered by a thin layer of compost and inoculated with activated sludge from a municipal WWTP. Operating conditions under high loads of toluene were selected to force plant failure by clogging. The biofilter achieved a remarkably maximum elimination capacity of 595 g toluene m−3 h−1 (1280 g toluene m−3 h−1 based on the first 25 cm of the biofilter). The evolution of biofilter performance and biomass growth over the packing material were studied until the reactor collapsed. Several variables related to biomass growth such as reactor weight, oxygen consumption, CO2 production, substrate removal and pressure drop were monitored. Alternated periods of substrate supply and starvation were tested to assess biomass growth and detachment. Moreover, pH and biomass content were periodically measured in the leachate to determine the washing efficiency of intermittent watering. Pressure drop measurements demonstrated that watering was an effective technique to wash the excess of biomass accumulated. Experimental data also permitted to determine important parameters for biofilter modeling as the biomass growth yield and the stoichiometric coefficients of toluene biological oxidation. Variables monitored are sensitive to biomass accumulation and provided enough description of the system towards development of a comprehensive model considering biomass growth to predict and prevent clogging in equivalent processes.
    The Chemical Engineering Journal 10/2012; 209:661–669. DOI:10.1016/j.cej.2012.08.018 · 4.32 Impact Factor
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    • "Since some carbonyl compounds produced by photodegradation promoted the mass transfer and removal of ␣-pinene, higher removal capabilities and CO 2 productions were achieved in the combined BTF. Media compaction, a significant indicator that affected the stable performance of biofilter, is generally measured by the pressure drop across the filter bed or the length of packings [41] [42]. Once media compactions happened, deteriorating phenomena (clogging , channeling and lower removal capability) would occur during the subsequent operation. "
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    ABSTRACT: Excessive biomass accumulation and bio-activity loss in biofilter (BF) and biotrickling filter (BTF) can lead to unreliable long-term operation. In this study, UV photodegradation was developed as a strategy of controlling biomass accumulation to recover BF and BTF for the treatment of gaseous alpha-pinene (α-pinene) over long-term period. With the addition of UV, an overall efficiency of more than 85% was re-achieved in BTF since excessive biomass was removed. Due to continuous positive effects by UV photodegradation, biomass concentration in the BTF was kept at a normal level (9.25–9.58kgm−3dry carrier), and the maximum elimination capacity and CO2 production increased by 4.2 and 6.2 times that achieved by the deteriorated BTF. Microbial analysis revealed that microbial community structure in BTF became more complicated with the addition of UV photodegradation. Kinetic analysis indicated that photodegradation could improve the removal process of α-pinene in BTF. Contrarily, UV photodegradation could not recover BF based on similar experiments. These findings provided a potential use of UV photodegradation for maintenance of biotrickling filtration efficient for gaseous pollutants removal over long-term operation.
    The Chemical Engineering Journal 10/2011; 175(1):316-323. DOI:10.1016/j.cej.2011.09.113 · 4.32 Impact Factor
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    • "** Jeong et al. (2008) Mature pig compost, forest soil and packing material made of poly ethylene Activated sludge 80 Wu et al. (2006) Food waste compost and pig manure compost Poly urethane foam (PUF) "
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    ABSTRACT: Biofiltration is fast emerging as a feasible option for treating odorous compounds and other volatile organic compounds (VOCs) from process waste -gas streams using microorganisms attached to porous support matrix. Compost, owing to its inherent physico-chemical and biological characteristics, has shown to be a promising filter material in biofiltration to treat both hydrophobic and hydrophilic gas -phase VOCs at low concentrations and high gas flow rates. This study aimed at evaluating the potential of a laboratory-scale biofilter, inoculated with mixed culture, to remove gas-phase xylene from a synthetic waste gas stream. The performance of the biofilter was studied by varying the flow rate from 0.024 to 0.072 m 3 /h, corresponding to empty bed residence times varying between 0.81 -2.45 min and by changing the inlet loading rates (ILR) between 3.5 to 208 g/m 3 .h. Removal efficiencies higher than 68% were achieved for xylene loading rates lesser than 60 g/m 3 .h. However, due to the hydrophobic nature of the pollutant, xylene, that hinders mass transfer, and/or substrate inhibition to the microorganisms, a significant reduction in the removal efficiency was observed at high xylene concentrations. The results demonstrate the potential of compost biofilter to handle microorganism-tolerable xylene loads under steady-state conditions.
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