Evaluation Of Tubular Biofilter For Styrene Removal From Waste Gas Streams

Styrene (vinyl benzene) was an important chemical raw material which hadvarious applications. In the process of styrene production and utilization, emissionof low concentration styrene gas might occur. Styrene gas, which was very harmful,was a well known carcinogen, and could cause gene to mutate. Moreover, it was alsoa photo-chemical agent, which could produce secondary pollutants such as ozonethrough degradation. Styrene pollutes the air and affects human health both directlyand indirectly. Contamination by styrene was a rising concern.Gas phase bio-filter was commonly used in this kind of pollution. The waste gasflows through the bio-filter. At this time, the pollutants in the gas phase will transferto liquid phase. Or, these pollutants will adhere to inner surface of micro-organismgroups in the filtering media. After that, these pollutants will degrade into inorganicmaterial through metabolism of micro-organism groups.Compared to traditional treatment methods (combustion, adsorption,condensation at low temperature, absorption), gas phase bio-filter had manyadvantages such as good removal efficiency, stable operation, low operation cost, easeto operate and manage, no secondary pollution and low capital cost.However, it did have flaws. When bio-filter was used to treat low concentration,large quantity organic gas, the removal efficiency generally decreased after long timeoperation.This article examines styrene removal efficiencies by self-made tubular bio-filterat start up phase under different parameters. The parameters we concern in this articlewere inflow styrene concentration, retention time, spraying intensity, inflow gas flowrate. The results suggest that tubular bio-filter can achieve good removal efficiency ofstyrene and overcome disadvantage of traditional bio-filter, such as unevendistribution of nutrition and VOCs. Bio-filter takes20days to finish start-up phase.When retention time was set at15seconds, inflow styrene concentrations are set at20,40,80mg/m3， the average removal efficiencies are95%、92%and50%correspondingly. When organic loading was set at9.6g/(m3·h), retention times wereset at60、30、15s, the average removal efficiencies were all above90%. Whenspraying intensity were set at0.38、0.75、1.50s/min, the average removal efficienciesalso exceed90%. Same removal efficiencies observed when inflow gas flow rate were set at0.25、0.12、0.06m3/h. During this research, bio-filter demonstrates a degradationcapability of low concentration styrene gas for a long operation time even withoutbackwash.