Measurements and modeling of heat generation in a trickling biofilter for biodegradation of a low concentration volatile organic compound (VOC)
ABSTRACT The experimental and theoretical heat generation behavior of a trickling biofilter treating toluene is discussed. The experimental results show that the temperature of the packed bed has a significant effect on the purification performance of the trickling biofilter and that an optimal operation temperature exists between 30 and 40 °C. During the gas–liquid co-current flow, the temperature in the packed bed gradually rises along the direction of the gas and liquid flow due to the exothermic biodegradation of toluene. The temperature rise between the inlet and outlet of the trickling biofilter increases with an increase in the gas flow rate and inlet toluene concentration. In addition, a larger liquid flow rate leads to a smaller temperature rise. The heat generation process occurring in the trickling biofilter is modeled by representing the packed bed as an equivalent set of parallel capillary tubes covered by the biofilm. The temperature profile in the packed bed during the liquid–gas co-current flow is analyzed by simultaneously solving the problem of gas–liquid two-phase flow and heat and mass transfer through the liquid film and biofilm. It is shown that the model agrees well with the experimental data, predicting the variations of the temperature rise between the inlet and outlet of trickling biofilter with the increasing gas and liquid flow rates.
Article: Performance evaluation of a thermophilic biofilter for the removal of MTBE from waste air stream: Effects of inlet concentration and EBRT[show abstract] [hide abstract]
ABSTRACT: a b s t r a c t The removal of MTBE from a waste air stream was investigated using a bench scale thermophilic biofilter. After developing a high population of acclimated organisms capable of degrading MTBE, the biofilter achieved complete removal of MTBE at an inlet concentration of 100 ppm during startup. The performance of the biofilter was then evaluated under different operational conditions, including MTBE concentrations ranging from 100 to 3000 ppm and empty bed retention times (EBRTs) between 15 and 60 s, corresponding to inlet mass loading of 20–650 g-MTBE m −3 h −1 . All the experiments were conducted at a constant bed temperature of 52 ± 3 • C. The biofilter efficiently treated MTBE at loads up to 330 g-MTBE m −3 h −1 with very high removal efficiencies of greater than 99%. The elimination and mineralization capacities at critical loading rate were 326 and 165 g-MTBE m −3 h −1 , respectively. The findings of this study indicate that thermophilic biofiltration can be a promising process for treatment of waste air streams containing toxic compounds.Biochemical Engineering Journal 01/2009; 45:152-156. · 2.64 Impact Factor
Article: Comparative study of the eliminating of waste gas containing toluene in twin biotrickling filters packed with molecular sieve and polyurethane foam.[show abstract] [hide abstract]
ABSTRACT: Two kinds of packing materials, molecular sieve (MS) and polyurethane foam (PUF), were loaded into two identical biotrickling filters respectively to compare the microbial removal efficiency of waste gas containing toluene by seeding with same bacteria. The affecting parameters of the removal performance, such as gas flow rates, inlet toluene concentrations, periods of starvation, were investigated in detail in biotrickling filters. The results demonstrated that both of the packing materials exhibited high toluene degradation efficiency when the gas flow rates ranged from 100 L h(-1) to 600 L h(-1). For MS, the total maximum removal efficiency (RE) of toluene maintained 100% when the gas flow rates increased from 100 L h(-1) to 200 L h(-1) accompanied with the decrease of empty bed residence time (EBRT) from 266s to 133s. However, as for PUF, merely 97.64% RE was obtained at the gas flow rate of 100 L h(-1) and the EBRT of 266s. With further increasing the gas flow rates (to 600 L h(-1)) and decreasing the EBRTs (to 44s), both the total REs of toluene for MS and PUF decreased to 70.68% and 63.18%, respectively. When varying the inlet toluene concentrations, the REs for MS are able to maintain nearly 100% at the inlet concentration of 9.19 mg L(-1) or below, and with the maximum elimination capacity (EC) of 373.24 gm(-3)h(-1) (RE=100%) at the inlet concentration of 9.19 mg L(-1). Contrastively, the maximum EC of PUF was only 119.41 gm(-3)h(-1) (RE=56.66%) at the inlet concentration of 5.19 mg L(-1). As illustrated by different starvation period (2, 10 and 60 days), MS possessed shorter recovery time (9h for 2 days, 17 h for 10 days and 324 h for 60 days starvation, respectively) than PUF (14 h for 2 days, 24h for 10 days and 324 h for 60 days starvation, respectively). Based on its higher removal capacity of toluene and shorter recovery time, MS would be a better choice than PUF for packing material used for biotrickling filter.Journal of hazardous materials 01/2009; 167(1-3):275-81. · 4.14 Impact Factor
Article: Comparison of the removal of ethanethiol in twin-biotrickling filters inoculated with strain RG-1 and B350 mixed microorganisms.[show abstract] [hide abstract]
ABSTRACT: This study aims to compare the biological degradation performance of ethanethiol using strain RG-1 and B350 commercial mixed microorganisms, which were inoculated and immobilized on ceramic particles in twin-biotrickling filter columns. The parameters affecting the removal efficiency, such as empty bed residence time (EBRT) and inlet concentration, were investigated in detail. When EBRT ranged from 332 to 66 s at a fixed inlet concentration of 1.05 mg L(-1), the total removal efficiencies for RG-1 and B350 both decreased from 100% to 70.90% and 47.20%, respectively. The maximum elimination capacities for RG-1 and B350 were 38.36 (removal efficiency=89.20%) and 25.82 g m(-3) h(-1) (removal efficiency=57.10%), respectively, at an EBRT of 83 s. The variation of the inlet concentration at a fixed EBRT of 110 s did not change the removal efficiencies which remained at 100% for RG-1 and B350 at concentrations of less than 1.05 and 0.64 mg L(-1), respectively. The maximum elimination capacities were 39.93 (removal efficiency=60.30%) and 30.34 g m(-3) h(-1) (removal efficiency=46.20%) for RG-1 and B350, respectively, at an inlet concentration of 2.03 mg L(-1). Sulfate was the main metabolic product of sulfur in ethanethiol. Based the results, strain RG-1 would be a better choice than strain B350 for the biodegradation of ethanethiol.Journal of hazardous materials 11/2010; 183(1-3):372-80. · 4.14 Impact Factor