Estimating the formation and thickness of a liquid layer on the surface of a packing material in biofiltration and their effects on gaseous toluene removal
Estimating the formation and thickness of a liquid layer on the surface of a packing material in biofiltration and their effects on gaseous toluene removal
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DOI：
10.2174/2212711906666181120125211
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
Ahmad Masoud Mansooria and Takashi Higuchi
中科院分区：
文献类型：
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作者：
Ahmad Masoud Mansooria and Takashi Higuchi
生物过滤系统中用于处理气态挥发性有机物的填料，在实际使用中应具有最佳的含水量。这是因为高体积的水增加了扩散阻力，而低水含量降低了微生物活性。因此，需要确定填料上液层的厚度，以确定目标污染物的传质过程。但是，由于一般包装材料的表面结构复杂，无法直接测量。在这项研究中，理想的生物过滤表面，人工制备一个平面膜表面与单培养的生物量和已知厚度的液体层。然后，在相当大的液体厚度范围内，在此生物质表面上观察到气态甲苯的吸附速度。然后测量水从多孔PVF聚乙烯醇缩甲醛（PVF）材料蒸发的速度。最后，根据实验结果和一套汽化数学模型，计算了PVF材料的液面厚度与含水量之间的关系。填料表面生物质上的水层厚度存在一个合适的范围。在一种情况下，对于气态甲苯，该厚度被引用为约0.1-0.2 mm。PVF材料被认为在其水含量的约50-60%时形成如此厚的水层。当生物质在PVF材料表面生长时，影响水层形成的含水量条件发生变化。范围从新材料的约70%下降到富含生物质材料的约55%。本研究定量阐明了生物过滤填料存在最佳含水量范围的原因，即，在一定的含水量范围内，在填料表面建立适当的液层厚度。
Packing materials, which are used in biofiltration systems treating gaseous volatile organic compounds, are expected to have optimal water content in their actual use. This is because high volume of water increases the diffusion resistance while low water content decreases microbial activity. Therefore the thickness of the liquid layer on the packing material needs to be identified to determine the mass transfer process of target pollutants. However, it cannot be measured directly due to the complicated surface structure of general packing materials. In this study, ideal biofiltration surfaces were prepared artificially by coating a plain membrane surface with mono-cultured biomass and a known thickness of liquid layer. The sorption velocity of gaseous toluene was then observed, within a considerable range of liquid thicknesses, on this biomass surface. The velocity of water vaporization from a porous PVF poly-vinyl formal (PVF) material was then measured. Finally, the relationship between thickness of liquid surface and the water content of the PVF material was calculated based on the experimental results and a set of mathematical models on vaporization. There is an appropriate range for the thickness of the water layer thickness on the biomass at the surface of packing material. In one case, this thickness was cited as approximately 0.1–0.2 mm for gaseous toluene. The PVF material was thought to form such a thick water layer at around 50–60% of its water content. The water content conditions that affect the formation of the water layer changed when biomass grew on the surface of the PVF material. The range declined from around 70% for new material to around 55% for biomass-rich material. This study quantitatively clarified the reason why there is optimal range of water content for the packing material of biofiltration; i.e., appropriate liquid layer thickness at the surface of packing materials is built by a certain range of water content.