Fibrous Bed Bioreactor Research Articles

Performance of fibrous bed bioreactor for treating odorous gas. Scientific note.

A fibrous bed bioreactor was used for treatment of odorous volatile fatty acid (VFA). The effect of gaseous VFA (acetic, propionic, and butyric acids) mass loading on the bioreactor performance was investigated. The VFA degrading microbial culture was selected from activated sludge by the three VFAs using a shake-flask culture. The selected microorganisms were then immobilized in a biofilter using cotton fabric as packing material. In the biofiltration experiment, the inlet gas flow rates ranged from 1 to 4 L/min, the total VFA concentrations ranged from 0.10 to 0.43 g/m3, and the resulting total mass loadings of VFA studied ranged from 9.7 to 104.3 g/m3/h. At total mass loading of 104.3 g/m3/h, the VFA removal efficiency was 87.7%. Higher removal efficiencies (>90%) were achieved at mass loadings below 50.3 g/m3/h.

A trickling fibrous-bed bioreactor for biofiltration of benzene in air

A novel trickling fibrous-bed bioreactor was developed for biofiltration to remove pollutants present in contaminated air. Air containing benzene as the sole carbon source was effectively treated with a coculture of Pseudomonas putida and Pseudomonas fluorescens immobilized in the trickling biofilter, which was wetted with a liquid medium containing only inorganic mineral salts. When the inlet benzene concentration (C gi ) was 0.37 g/m 3 , the benzene removal efficiency in the biofilter was greater than 90% at an empty bed retention time (EBRT) of 8 min or a superficial air flow rate of 1.8 m 3 /m 2 .h. In general, the removal efficiency decreased but the elimination capacity of the biofilter increased with increasing the inlet benzene concentration and the air (feed) flow rate. It was also found that the removal efficiency decreased but the elimination capacity increased with an increase in the loading capacity, which is equal to the inlet concentration divided by EBRT. The maximum elimination capacity achieved in this study was ∼11.5 g/m 3 .h when the inlet benzene concentration was 1.7 g/m 3 and the superficial air flow rate was 3.62 m 3 /m 2 .h. A simple mathematical model based on the first-order reaction kinetics was developed to simulate the biofiltration performance. The apparent first order parameter K 1 in this model was found to be linearly related to the inlet benzene concentration (K 1 =4.64-1.38 C gi ). The model can be used to predict the benzene removal efficiency and elimination capacity of the biofilter for benzene loading capacity up to ∼30 g/m 3 .h. Using this model, the maximum elimination capacity for the biofilter was estimated to be 12.3 g/m 3 .h, and the critical loading capacity was found to be 14 g/m 3 .h. The biofilter had a fast response to process condition changes and was stable for long-term operation; no degeneration or clogging of the biofilter was encountered during the 3-month period studied. The biofilter also had a relatively low pressure drop of 750 Pa/m at a high superficial air flow rate of 7.21 m 3 /m 2 .h, indicating a good potential for further scale up for industrial applications.

Acetate production from whey lactose using co-immobilized cells of homolactic and homoacetic bacteria in a fibrous-bed bioreactor.

Acetate was produced from whey lactose in batch and fed-batch fermentations using co-immobilized cells of Clostridium formicoaceticum and Lactococcus lactis. The cells were immobilized in a spirally wound fibrous sheet packed in a 0.45-L column reactor, with liquid circulated through a 5-L stirred-tank fermentor. Industrial-grade nitrogen sources, including corn steep liquor, casein hydrolysate, and yeast hydrolysate, were studied as inexpensive nutrient supplements to whey permeate and acid whey. Supplementation with either 2.5% (v/v) corn steep liquor or 1.5 g/L casein hydrolysate was adequate for the cocultured fermentation. The overall acetic acid yield from lactose was 0.9 g/g, and the productivity was 0.25 g/(L h). Both lactate and acetate at high concentrations inhibited the homoacetic fermentation. To overcome these inhibitions, fed-batch fermentations were used to keep lactate concentration low and to adapt cells to high-concentration acetate. The final acetate concentration obtained in the fed-batch fermentation was 75 g/L, which was the highest acetate concentration ever produced by C. formicoaceticum. Even at this high acetate concentration, the overall productivity was 0.18 g/(L h) based on the total medium volume and 1.23 g/(L h) based on the fibrous-bed reactor volume. The cells isolated from the fibrous-bed bioreactor at the end of this study were more tolerant to acetic acid than the original culture used to seed the bioreactor, indicating that adaptation and natural selection of acetate-tolerant strains occurred. This cocultured fermentation process could be used to produce a low-cost acetate deicer from whey permeate and acid whey.

Acetic acid production from fructose by clostridium formicoaceticum immobilized in a fibrous-Bed bioreactor

The fermentation kinetics of acetic acid production from fructose by Clostridium formicoaceticum was studied at pH 7.6 and 37 degreesC. Recycle batch, fed-batch, and continuous fermentations using immobilized cells in a fibrous-bed bioreactor were studied for their potential application in producing acetic acid from fructose, a fermentable sugar commonly found in corn steep liquor and many other food processing wastes. For the immobilized cell fermentation, acetic acid yield from fructose was approximately 1.0 g/g, with a final acetate concentration of approximately 78 g/L and the overall reactor productivity (based on the fibrous bed bioreactor volume) of approximately 0.95 g/(L.h) in the fed-batch fermentation. For a similar fed-batch fermentation with free cells, acetic acid yield was approximately 0.9 g/g, the highest final acetate concentration was approximately 46 g/L, and the overall productivity was approximately 0.12 g/(L.h). In the continuous fermentation with immobilized cells, the reactor productivity decreased from 3.2 to 1. 3 g/(L.h) as retention time increased from 16 to 72 h to reach 100% conversion. Compared to free-cell fermentations, the superior performance of the fibrous-bed bioreactor can be attributed to the high density (>30 g/L) of viable cells immobilized in the fibrous bed. The fermentation product, acetic acid, was found to be a noncompetitive inhibitor to the cells. However, the immobilized cells had a higher maximum production rate (pmax) and a higher value for the inhibition rate constant (Kp) than those for the free cells, suggesting that the immobilized cells in the fibrous-bed bioreactor were less sensitive to acetic acid inhibition than the free cells. This improvement in kinetic behaviors for immobilized cells confirms that the fibrous-bed bioreactor can be used as an effective tool for adapting and screening for acetate-tolerant strains.

Hydrogen sulphide and volatile fatty acid removal from foul air in a fibrous bed bioreactor

Odour control in Hong Kong has been addressed as an important issue by the authorities, since odour pollution is generated from many sources including wastewater treatment plants. Although a number of existing technologies are available for odour abatement and control, biological technique is still more attractive due to its low operating cost and ease of maintenance. A newly innovated fibrous bed bioreactor with twin columns was specially designed and constructed in our laboratory, in which an inner column was centred in an outer column. The bioreactor was fully filled with water in order to absorb the odorous components from foul gas and also contained both suspended and attached biomass to degrade the absorbed odorous pollutants. In this study, hydrogen sulphide (H2S) and butyric acid (C4H8O2) were used as odorous components and successfully removed from synthetic foul gases. Many factors affecting the H2S and butyric acid removal efficiency and maximum elimination capacity, such as pH of water solution, gas flow rate and its fluctuation, and sulphate content in solution have been studied. The experimental results demonstrated that the reduction rates of 97.8% for H2S and 99.9% for butyric acid were achieved in this experimental condition. It is proved that this bioreactor was a compact odorous gas treatment system with an application potential for treating foul air with high odour strength and low airflow rate such as the offensive gases from sludge treatment processes in a wastewater treatment plant.

Hydrogen sulphide and volatile fatty acid removal from foul air in a fibrous bed bioreactor

Odour control in Hong Kong has been addressed as an important issue by the authorities, since odour pollution is generated from many sources including wastewater treatment plants. Although a number of existing technologies are available for odour abatement and control, biological technique is still more attractive due to its low operating cost and ease of maintenance. A newly innovated fibrous bed bioreactor with twin columns was specially designed and constructed in our laboratory, in which an inner column was centred in an outer column. The bioreactor was fully filled with water in order to absorb the odorous components from foul gas and also contained both suspended and attached biomass to degrade the absorbed odorous pollutants. In this study, hydrogen sulphide (H2S) and butyric acid (C4H8O2) were used as odorous components and successfully removed from synthetic foul gases. Many factors affecting the H2S and butyric acid removal efficiency and maximum elimination capacity, such as pH of water solution, gas flow rate and its fluctuation, and sulphate content in solution have been studied. The experimental results demonstrated that the reduction rates of 97.8% for H2S and 99.9% for butyric acid were achieved in this experimental condition. It is proved that this bioreactor was a compact odorous gas treatment system with an application potential for treating foul air with high odour strength and low airflow rate such as the offensive gases from sludge treatment processes in a wastewater treatment plant.

5563069 Extractive fermentation using convoluted fibrous bed bioreactor : Yang Shang-Tian Dublin, OH, United States Assigned to The Ohio State University Research Foundation

5563069 Extractive fermentation using convoluted fibrous bed bioreactor : Yang Shang-Tian Dublin, OH, United States Assigned to The Ohio State University Research Foundation

Kinetics and stability of GM-CSF production by recombinant yeast cells immobilized in a fibrous-bed bioreactor.

The continuous production of murine granulocyte-macrophage colony-stimulating factor (GM-CSF) by recombinant yeast cells immobilized in a fibrous-bed bioreactor was studied. A high cell density of approximately 68 g/L and a GM-CSF productivity of approximately 3.5 mg/L.h were attained in the fibrous-bed bioreactor-fed with a rich (nonselective, pH 6.7) medium at a dilution rate of 0.16 h-1. The GM-CSF production was stable even though the fraction of plasmid-carrying cells in the reactor effluent gradually dropped below 5% over a period of 2 weeks. At the end of that period, the immobilized cells in the fibrous matrix still had a high fraction, approximately 26%, of plasmid-carrying cells. Similar results were obtained with reactors operated at 0.05 h-1 dilution rate and pH 4.0. Although the GM-CSF production was lower at pH 4, the reactor was stably operated for over 4 weeks without contamination or significant loss of productivity. The stable long-term GM-CSF production from the fibrous-bed bioreactor was attributed to the effect of cell immobilization on plasmid stability. Because GM-CSF production was growth-associated, as was found in batch fermentation with free cells, this stabilization effect cannot be attributed solely to the reduced cell growth in the immobilized cell environment. Plasmid-carrying cells were preferentially retained in the fibrous matrix, perhaps because their abilities to adhere to the fiber surface and to form cell aggregates were higher than those of plasmid-free cells.

Kinetics and stability of a fibrous-bed bioreactor for continuous production of lactic acid from unsupplemented acid whey

The kinetics and long-term stability of the fibrous-bed bioreactor were investigated for continuous lactic acid production from unsupplemented acid whey containing ~ 3.7% (w/v) lactose and ~ 0.8% (w/v) lactic acid, using immobilized cells of Lactobacillus helveticus at pH 5.5 and 42 °C. Depending on dilution rate and lactate concentration, reactor volumetric productivities ranged from 2.6 g l −1 h −1 to 7 g l −1 h −1. These productivities were approx. 10-times higher than those obtained in batch cultivations with free cells. The product inhibition followed noncompetitive kinetics, with the inhibition constant, K p, equal to 7.9 g l −1 and the maximum volumetric productivity, q′ max, equal to 20 g l −1 h −1. Lactate yield from lactose was > 95% (w/w). Reactor performance was stable for continuous, long-term operation for both sterile and nonsterile unsupplemented acid whey feeds for the 6-month period studied. Concentrated acid whey was also found to be an appropriate feedstock to this bioreactor. SEM micrographs showed a dense biofilm covering the fibrous reactor packing. Atypical cell morphology was also observed with the immobilized cells. Total cell density, including suspended cells, within the reactor exceeded 60 g 1 −1. The specific cell productivity was lower than for free cells, indicating a relatively low cell efficiency, perhaps due to diffusion limitation.

Continuous propionate production from whey permeate using a novel fibrous bed bioreactor

Continuous production of propionate from whey lactose by Propionibacterium acidipropionici immobilized in a novel fibrous bed bioreactor was studied. In conventional batch propionic acid fermentation, whey permeate without nutrient supplementation was unable to support cell growth and failed to give satisfactory fermentation results for over 7 days. However, with the fibrous bed bioreactor, a high fermentation rate and high conversion were obtained with plain whey permeate and de-lactose whey permeate. About 2% (wt/vol) propionic acid was obtained from a 4.2% lactose feed at a retention time of 35 to 45 h. The propionic acid yield was approximately 46% (wt/vol) from lactose. The optimal pH for fementation was 6.5, and lower fermentation rates and yields were obtained at lower pH values. The optimal temperature was 30 degrees C, but the temperature effect was not dramatic in the range of 25 to 35 degrees C. Addition of yeast extract and trypticase to whey permeate hastened reactor startup and increased the fermentation rate and product yields, but the addition was not required for long-term reactor performance. The improved fermentation results with the immobilized cell bioreactor can be attributed to the high cell density, approximately 50 g/L, attained in the bioreactor, Cells were immobilized by loose attachement to fiber surfaces and entrapment in the void spaces within the fibrous matrix, thus allowing constant renewal of cells. Consequently, this bioreactor was able to operate continuously for 6 months without encountering any clogging, degeneration, or contamination problems. Compared to conventional batch fermentors, the new bioreactor offers many advantages for industrial fermentation, including a more than 10-fold increase in productivity, acceptance of low-nutrient feedstocks such as whey permeate, and resistance to contamination. (c) 1994 John Wiley & Sons, Inc.

Continuous propionic acid fermentation by immobilized Propionibacterium acidipropionici in a novel packed‐bed bioreactor

Continuous propionic acid fermentations of lactate by Propionibacterium acidipropionici were studied in spiral wound fibrous bed bioreactors. Cells were imobilized by natural attachment to fiber surfaces and entrapment in the void volume within the fibrous matrix. A high cell density of approximately 37 g/L was attained in the reactor and the reactor productivity was approximately 4 times higher than that from a conventional batch fermentation. The bioreactor was able to operate continuously for 4 months without encountering any clogging, degeneration, or contamination problems. Also, the reactor could accept low-nutrient and low-pH feed without sacrificing much in reactor productivity. This new type of immobilized cell bioreactor is scalable and thus is suitable for industrial production of propionate.