A bioactive foam reactor for the removal of volatile organic compounds: system performance and model development

Abstract

A bioactive foam reactor (BFR), a novel bioreactor operated using surfactant foams and suspended microorganisms for the treatment of gaseous toluene, was investigated to characterize its performance with respect to the mass transfer and biodegradation rates. The BFR system consisted of two reactors in series; a foam column for toluene mass transfer using fine bubbles and a cell reservoir where suspended microorganisms actively biodegraded toluene. In this study, a series of short-term experiments demonstrated that the BFR could achieve stable removal performance and a high elimination capacity (EC) for toluene at 100.3 g/m3/h. A numerical model, combining mass balance equations for the mass transfer and subsequent biodegradation, resulted in reasonable agreement with the experimental findings. At an inlet toluene concentration of 100 ppm v, the toluene concentration in the liquid phase remained extremely low, indicating that the microbial activity was not hindered in the BFR system. However, the experimental and model prediction results showed that the actual mass of toluene transferred into the liquid phase was not closely balanced with the amount of toluene biodegraded in the BFR used in this study. Consequently, methods, such as increasing the effective volume of the foam column or the mass transfer coefficient, need to be implemented to achieve higher toluene EC and better BFR performance.

A bioactive foamed emulsion reactor for the treatment of benzene-contaminated air stream

“…Whereas the silicone DC in some of previous similar studies [3,5,13] was selected as biocompatible surfactant, but in this study, the Triton X-100 as an alternative showed good performance. This surfactant is biocompatible and has a good foaming ability [6,17]. The optimum concentration of organic phase was determined based on RE and EC of bioreactor.…”

“…major limitations [5][6][7]. Due to the low activity of the attached cells to packing bed, biofilters typically have low pollutant elimination capacities, while biotrickling filters often exhibit higher performance than biofilters, but often it can be clogged from excessive biomass growth on the bed, which results in high pressure drop and process instability [8][9][10].…”

“…Toluene as a representative of VOCs and oleic alcohol as an organic phase have been used in past studies [3,5,6]. The benzene has lower solubility (and bioavailability) in aqueous phase in comparison to toluene and therefore, it is biodegraded lower than toluene in the same condition.…”

“…The function of organic phase was to adsorb/desorb high concentration of pollutants. In comparison to biofilter and biotrickling filter, the BFRs have a high elimination capacity (EC) for large interfacial area between the gas and fine foam, but in the high concentration (generally higher than 300 mg m -3 ) removal efficiency (RE) in BFRs is reduced [3,6].…”

Enhanced toluene removal using granular activated carbon and a yeast strain Candida tropicalis in bubble-column bioreactors

“…The nutrient solution consisted of a hydrocarbon minimal medium (HCMM), containing 1.36 g/L KH 2 PO 4 , 1.42 g/L Na 2 HPO 4 , 0.5 g/L (NH 4 ) 2 SO 4 , 3.03 g/L KNO 3 , and a trace metal solution containing 0. 25 The yeast strain was cultured in a serum bottle containing the HCMM solution, with toluene vapor as a sole carbon and energy source. Sterilized air was sparged into the suspension for 2 min, and then the bottle was tightly caped with a Teflon-coated septum.…”