| In recent years, a large number of volatile organic compounds （VOCs）emissions which generated from the industry have seriously endangered the qualityof the environment and human health. The way of biological treatment on lowconcentrations of VOCs developed rapidly, in which the biotrickling filter （BTF） isconsidered to be efficient, economic and environmentally friendly, and does notproduce secondly pollution, but the removal efficiency is still low when degradingorganic gas with low water solubility on BTF, such as styrene, so how to improve theperformance of BTF on the degradation of organic gas with low solubility becomemore significant. In this study, we selected polyurethane foam as the media, thesludge from the sewage treatment plant as the seed sludge, the biofiltration ofstyrene vapors was investigated using two separate while ientical biotrickling filters,BTF1and BTF2, after both BTFs were successfully started up, we added TritonX-100to the nutrition solution which was fed to BTF2, to investigated theperformance of the BTF on the styrene degrading and the effect of the surfactant onits performance.During the start-up period, the inlet styrene concentration of both BTFs wasfixed at250mg/m3, and the gas residence time was fixed at30s, the results showedthat the gaseous styrene removal efficiency of both BTFs reached90%or morewithin8days, and can reach more than99%on day18, this proved that both BTFswere successfully stared. On day20, we added the surfactant BTF2and all otheroperation conditions remained same.This study investigated the performance of the BTFs for treating styrene wastegas under different inlet styrene concentrations. The results showed that, when fixedthe EBCT at30s, while increased the inlet styrene concentration to550,850and1700mg/m3, corresponding to the organic loading rate of65.25,100.85and201.7g/（m3·h）, the styrene removal efficiency of BTF1were87%,70%and49%,respectively, while the removal efficiency of BTF2which used the surfactant were96%,91%and82%, respectively. From the results we can concluded that, the use ofthe surfactant can improve the styrene degrading efficiency of the BTF on theseoperating conditions.Afterwards we continued study the performance of the BTFs for treating styrene waste gas under different EBCTs. During this period we continued to supply TritonX-100to BTF2, the organic loading rate of both BTFs fixed at237.29g/（m3·h）, toinvestigate the styrene removal efficiency of the BTF when the inlet styreneconcentration were2000,1000and500mg/m3, and the corresponding EBCT were30,15and7.5s, respectively. The results showed that the styrene removal efficiencyof BTF1were48%,47%and45%, respectively, while80%,79%and76%for BTF2which used the surfactant. From the results we can conclude that when operating ona constant loading rate, changing EBCT and inlet styrene concentration have littleeffect on styrene removal efficiency of BTF, and the use of Triton X-100candistinctly enhance the styrene removal efficiency of BTF on the reference operatingconditions.Finally we study the performance of the BTFs for treating styrene waste gasunder different gas flow rates. During this period we continued to supply TritonX-100to BTF2, the styrene concentration of both BTFs fixed at1500mg/m3, toinvestigate the styrene removal efficiency of the BTF when the EBCT were60,30and15s, while the corresponding styrene loading rates were88.98,177.96and355.92mg/m3, respectively. The results showed that the styrene removal efficiencyof BTF1were69%,52%and40%, respectively, while86%,82%and70%for BTF2which used the surfactant.The pressure drop of the BTF during the operation proved that, as the increaseof the inlet concentration and the gas flow rate, the pressure drop increase too. Whenthe styrene organic loading rate increase to237.3g styrene/（m3·h）, the pressure dropof BTF1increase to700Pa （70mm H2O）, and the clogging occurred, the styreneremoval efficiency dropped. But the pressure drop of BTF2which used thesurfactant is stable during the whole operation, with no clogging occurred. Theresults showed that the use of Triton X-100can effectively inhibit medium clogging.The research also study the effect of the height of the medium on the styreneremoval efficiency of BTF, the results showed that, as the thickness of the mediumincreases, the styrene removal efficiency of the BTF increases too, but when thethickness of the medium increases to a certain degree, the increase of the styreneremoval efficiency is not apparent. On this point, the conclusions of BTF1and BTF2are similarly.According to the comparison of results of BTF1and BTF2, it is concluded thatthe use of Triton X-100can improve the performance of BTF observably on thecondition of we experimented on, the degradation of gas stream styrene of BTF2 which added surfactant is higher than BTF1which was without surfactant.Meanwhile, from the pressure drop of BTF1and BTF2we can find that the use ofsurfactant can prevent the happening of clogging on the condition of weexperimented on. |
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