Removal Of Gaseous M-xylene By A Combined System Of UV Photocatalysis And Biotrickling Filtration

Rencently, more and more attention were paid to the air pollution caused by VOCs. A combined system of UV/TiO2 photocatalytic oxidation and bio-trickling filtration (PCO-BTF) was a new technology developed to improve the removal of VOCs. It is a promising technology for treatment of recalcitrant and/or high concentration volatile pollutants. In the present study, a combined system of UV/TiO2 photocatalytic oxidation and bio-trickling filtration (PCO-BTF) was developed to improve the removal rate of gaseous m-xylene. Different inlet concentration, empty bed residence times (EBTRs) and transient loading were operated. Single BTF was operated under the same conditions. The mechanism of PCO pretreatment was primary discussed.A m-xylene-degrading fungi was isolated and identified as Aspergillus sp.. The ceramsite (Φ:8-12 mm) was selected as packing materials. The experiment comparing the m-xylene removal performance by two system showed that the start-up period of the PCO-BTF system (20 d) was shortened by 3 days than the single BTF (23 d). The removal efficiencies (REs) of the combined system were much higher than those of the single one at EBRTs of 90 s,75 s,60 s and 45 s and inlet concentrations from 200-2600 mg/m3, the average removal efficiencies were about 20%-30%. In addition, as a pretreatment method, UV/TiO2-based photocatalysis showed a better adaption when encounter with transient loading of 5000 mg/m3 and 2000 mg/m3. Compared with single BTF, PCO-BTF system had strong resistance to shock loading. The intermediates of PCO pretreatments were acetone,2-methyl acrolein, 3-butene-2-ketone, acetic acid, etc. Primary discuss about mechanism of the PCO-BTF process showed that as pretreatment technology, UV-PCO converted the m-xylene into more soluble and biodegradable intermediates, the biotoxicity and volatility of gas concentration decreased, thus removal load by BTF decreased, keeping the system at stable operating state. The mechanism of the PCO-BTF process provided a potential use of UV/TiO2 photocatalysis for maintenance the efficient of biotrickling filtration for gaseous pollutants removal operation.