Prediction of microbial growth rate in biofilters by using the nutrient diffusion coefficient

✍ Scribed by Wu-Chung Chan; Zong-Yi Lin

• Publisher: Wiley (John Wiley & Sons)
• Year: 2005
• Tongue: English
• Weight: 148 KB
• Volume: 80
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.1282

✦ Synopsis

Abstract

In this study, an optimal process for preparing a synthetic filter material with nitrogen nutrient (PVA/peat/KNO~3~ composite beads) was developed for biofiltration and the optimal initial nitrogen concentration of the boric acid and phosphate aqueous solutions was found to be 3.94 and 1.52 g nitrogen L^−1^, respectively. The water‐soluble nitrogen content in the prepared composite beads was higher than that of the compost. The mass transport process for the water‐soluble nitrogen dissolving out of the composite beads occurred in two stages: external mass transport occurred in the early stage and an intraparticle diffusion process occurred in the long‐term stage. The rate of water‐soluble nitrogen dissolving out during the external mass transport process increased with increasing the concentration of KNO~3~ aqueous solution and that during the intraparticle diffusion process had a maximum value for the composite beads that had been immersed in 0.384 M KNO~3~. The path of water‐soluble nitrogen dissolving out from the composite beads was that the water‐soluble nitrogen dispersed in the peat phase firstly diffused into the outer poly(vinyl alcohol) (PVA) phase and then it diffused out of the bead surface. The percentage of volatile organic compounds (VOCs) removed by the biofilter from an air stream remained above 99% for 230 days for the composite beads that had been immersed in KNO~3~ before packing. The microbial growth rate had a maximum value for the composite beads that had been immersed in 0.384 M KNO~3~ and was higher than that of the compost by a factor of 1.49. The rate of nitrogen dissolving out during the intraparticle diffusion process could be used as an index to predict the microbial growth rate in the biofilter. Copyright © 2005 Society of Chemical Industry