Modeling of a bacterial and fungal biofilter applied to toluene abatement: Kinetic parameters estimation and model validation

Abstract

Biofiltration has been established as a promising alternative to conventional air pollution control technologies. However, gas biofilters modeling has been less developed than experimental research due to the complexity of describing the fundamental processes and the lack of globally accepted\ud physical, chemical and biological parameters. In addition, biofiltration modeling based on degradation activity of fungi has been rarely considered.\ud For this reason, in thiswork, a dynamic model describing toluene abatement by a bacterial and fungal biofilter is developed, calibrated and validated.\ud The mathematical model is based on detailed mass balances which include the main processes involved in the system: convection, absorption, diffusion and biodegradation. The model was calibrated and validated using experimental data obtained from two equal lab-scale biofilters packed\ud with coconut fiber and pine leaves, respectively. Both reactors were operated under similar conditions during 100 days at an empty bed residence time of 60 s and an average inlet load of 77 g toluenem−3 h−1. Biofilters were initially inoculated with a bacterial consortium, even though reactors\ud were mostly colonized by fungi after 60 days of operation according to microscopic observation and reactors pH. Removal efficiency increased notably from 20% for the bacterial period to 80% for the fully developed fungal biofilters. Since kinetic parameters are strongly dependent on the\ud biological population, semi-saturation constants for toluene and maximum growth rates were determined for bacterial and fungal operation periods.\ud Kinetic parameters were fitted by means of an optimization routine using either outlet concentrations or removal efficiency data from the coconut fiber biofilter. A novel procedure in gas biofilters modeling was considered for checking the model calibration, by the assessment of the parameters confidence interval based on the Fisher Information Matrix (FIM). Kinetic parameters estimated in the coconut fiber reactor were validated in the pine leaves biofilter for bacterial and fungal operation. Adequate model fitting to the experimental outlet gas concentration for both bacterial and fungal operation periods was verified by using a standard statistical test.Peer ReviewedPostprint (published version

Biofilm dynamics characterization using a novel DO-MEA sensor: mass transport and biokinetics

“…According to Dorado et al (2008) µ max /Y x/o may be lumped in a coefficient q max (mg DO·g VSS -1 ·s -1 ).…”

An Investigation on the Efficiency of Air Purification Using a Biofilter with Activated Bed of Different Origin

“…Since toluene is an organic material much less soluble in water, its concentration after this layer varied not as much as that of acetone. Removal efficiency of pollutants from cleaned air depends on gas residence time in biofilters (AlvarezHornos et al, 2007;Dorado et al 2008Dorado et al , 2010Dorado et al , 2012aGracy et al, 2006;Hwang and Tang, 1997;Jeong at al., 2006;Qi, 2005;Yoon and Park, 2002;Zilli et al, 2001). The longer is the empty bed residence time (EBRT) of polluted gas the higher removal efficiency can be observed.…”

“…In the recent papers of Dorado et al (2008Dorado et al ( , 2010Dorado et al ( , 2012a the authors provided more information on the performance of biofilters packed with different hybrid packing material covered by a thin layer of compost and inoculated with activated sludge from a municipal WWTP and applied them to purify air containing toluene vapour. Dorado et al (2012a) found that biomass accumulation in a biofilter was enhanced by the high toluene load, particle size of the material, and its spatial distribution in the bed enabled to collect information on biomass growth.…”

Preliminary Acclimation Strategies for Successful Startup in Conventional Biofilters

“…Thus, different mathematical and statistical models have been proposed in the literature. [17][18][19][20][21] Nevertheless, microbial growth with degrading activity is a wholly undetermined key parameter that governs biofilter "success." The support material itself can supply the biomass responsible for degradation.…”