Packed-bed Bioreactor Research Articles

CFD modeling of formaldehyde biodegradation in an immobilized cell bioreactor with disc-shaped Kissiris support

Packed-bed bioreactors (PBRs) have been recognized as a breakthrough technology in industrial wastewater treatment plants due to high removal efficiency and low investment and operating cost. A coupled computational fluid dynamic (CFD) model, combining the fluid dynamics with biochemical reactions was developed to simulate the dynamic behavior of formaldehyde (FA) biodegradation by Ralstonia eutropha in an immobilized cell bioreactor with disk-shaped Kissiris pieces operating in batch-recycling and continuous mode. The multiphase CFD model was investigated to promote the design, optimization and scale-up of the existent environmental technologies on the decontamination of aqueous streams. The Eulerian CFD model was developed to evaluate the effect of different inlet substrate concentrations (1.67–20mol/m3 of FA) and feed flow rates (6–60.3mL/min) on the treatment efficiency under unsteady-state condition by visualizing concentration profiles for FA depletion. To validate the CFD model effectively, the theoretical calculations were compared against experimental biodegradation data reported in the literature and the time-dependent simulation results illustrated a satisfactory agreement with the experimental data. The results clearly demonstrated that the bioreactor operating in batch-recycling mode was more efficient in means of pollutant elimination while increasing the feed flow rate and inlet FA concentration had reverse effect on FA removal efficiency of the bioreactor. The Eulerian computations have shown promising results on how fluid dynamics can be correlated with biochemical reaction model (Luong inhibition model) and reasonably predict the formaldehyde concentration variations along the bioreactor.

Gas mass transfer with microbial CO2 fixation and poly(3-hydroxybutyrate) synthesis in a packed bed bioreactor

Gas mass transfer is the rate-limiting step in CO2 fixation by a hydrogen-oxidizing bacterium Cupriavidus necator under chemolithoautotrophic conditions. The mass transfer rates (i.e. the gas uptake rates) were measured in a packed bed bioreactor under the conditions of microbial growth on CO2. The kLa values of O2 and H2 were determined under either O2 or H2 limitation, respectively, and the ratio was proportional to a square root ratio of the molecular diffusivities in water, indicating that a surface renew model is suitable for the gas mass transfer in the packed bed. At a low gassing rate, the O2 mass transfer coefficient was to different extent affected by packing materials, bed geometry, liquid velocity, and liquid distribution. The liquid distributor and/or bed void space exhibited a high effect on the mass transfer coefficient. With microbial growth, the gas fermentation was becoming limited either by dissolved O2 or H2, depending on gas composition, but neither O2 nor H2 limitation could trigger the formation of a substantial amount of poly(3-hydroxybutyrate) (PHB) under nutrient-rich conditions. Instead, when a nitrogen nutrient control strategy was applied, PHB synthesis was significantly improved and the PHB content reached up to 67wt% of cell mass.

Tertiary nitrogen removal using simultaneous partial nitrification, anammox and denitrification (SNAD) process in packed bed reactor

The study aimed to polish wastewater effluent from an activated treatment system for nitrogen removal by a packed bed bioreactor (PBR). The nitrogen removal via simultaneous partial nitrification, anammox and denitrification (SNAD) process was investigated with different hydraulic retention times (HRTs). The results show that both effluent ammonia- and nitrate-nitrogen concentrations approached to 0 mg/L at the HRT as low as 3 h. The total nitrogen removal efficiency decreased from an average of 84% at both 18- and 24-h HRTs to 38% at 3-h HRT. This low nitrogen removal efficiency was due to the presence of incomplete degradation of organic nitrogen at shorter HRTs. The analysis using quantitative real-time polymerase chain reaction resolves that the ratio of ammonia-oxidizing bacteria (AOB) to the domain Eubacteria changed limited in the range between 2.8 and 4.0% during the continuous operation. Meanwhile, the nitrite-oxidizing bacteria (NOB) increased from 0.0 to 2.9% when the HRT was gradually reduced to 3 h. The anammox bacteria accounting for 30.5% of microbial consortia dominated the AOB and the NOB at the 3-h HRT. In sum, inorganic form of nitrogen in a typical wastewater plant effluent could be efficiently polished via SNAD process in the PBR.

Biodegradation of Phenol and Sodium Salicylate by Pseudomonas putida BCRC 14365 in Batch and Packed-Bed Bioreactors: Model Development and Verification

AbstractKinetic biodegradation of single phenol and sodium salicylate (SA) by Pseudomonas putida Bioresource Collection and Research Center (BCRC) 14365 was studied at 30°C and pH 7.0. Experiments ...

Scale-up of biodiesel synthesis in a closed-loop packed-bed bioreactor system using the fermented solid produced by Burkholderia lata LTEB11

The enzymatic route for biodiesel production is environmentally attractive, but costs need to be reduced and reaction times shortened. Costs can be reduced by producing lipases by solid-state fermentation and using the fermented solids directly to catalyze the ethyl-esterification of fatty acids in solvent-free media. However, the esterification studies done to date with fermented solids have involved 12g or less of fermented solids and reaction times greater than 30h. The aim of the current work was therefore to increase the scale of the process by an order of magnitude, while also decreasing the reaction time, using bi-distilled olein as the source of fatty acids. The best result was obtained with a molar ratio of ethanol to fatty acids of 1.5:1, in a process in which 245g of ethanol and 1000g of olein were circulated in a closed-loop system through a column containing 120g of dry fermented solids. A two-compartment reservoir was used, with the water in the outflow of the column being decanted in the first compartment. The organic phase that passed to the second compartment was agitated and fed back to the column. This system gave 88% conversion in 24h. This system was used in 6 successive 48-h batches with the same dry fermented solids, in which a total of 4.6kg of ester was produced. These are promising results that lay the basis for further scale-up studies.

Intermittent agitation contributes to uniformity across the bed during pectinase production by Aspergillus niger grown in solid-state fermentation in a pilot-scale packed-bed bioreactor

Solid-state fermentation could be used to produce low-cost pectinases that could then be used to saccharify pectin in citrus waste biorefineries. Recently, we produced pectinases in a pilot-scale packed-bed bioreactor, growing Aspergillus niger on a substrate mixture consisting of 27kg of wheat bran and 3kg of sugarcane bagasse (dry mass). However, the agglomeration of particles and shrinkage of the bed created preferential flow paths, leading to overheating within the bed and poor uniformity of pectinase levels at the end of the fermentation. In the current work, we used intermittent agitation as a strategy to minimize agglomeration, comparing one agitation (10h), three agitations (at 8, 10 and 12h) and five agitations (every 2h from 8 to 16h). The pectinase activity in the bed was uniform after agitation, but poor uniformity occurred when the bed was left unmixed for more than 10h. The best regime was that with three agitations: For 15 samples removed from different vertical and horizontal positions of the bed at 20h, the average pectinase activity was 22Ug−1, with a sample standard deviation of 2Ug−1. We conclude that the use of intermittently-mixed packed-bed bioreactors is a promising strategy for producing pectinases in solid-state fermentation.

Biosorption of Heavy Metals from Fertilizer Industrial Waste Water Using Rice Husk (RH) and Groundnut Husk (GH) Powder in a Packed Bed Bioreactor

Groundnut husk (GH) and Rice husk (RH) were used as adsorbents to remove Mn2+, Zn2+ and Pb2+ ions from fertilizer industrial waste water. Continuous adsorption experiment was conducted to examine the effect of adsorbent mass, pH, temperature and adsorbent combination on adsorption of Mn2+, Zn2+ and Pb2+ from fertilizer industrial waste water. The results showed that the adsorption of the metal ions was adsorbent mass, pH, and temperature dependent. The optimum adsorbent mass was 60 g, optimum pH was pH 5 and pH 6 and optimum temperature was 60°C for adsorption of heavy metal ions. The Langmuir biosorption isotherm provided the best fit for sorption of Mn2+, Zn2+ and Pb2+ using groundnut husk as indicated by their correlation coefficient (R2) of 0.998, 0.676 and 0.297 while the freundlich biosorption isotherm had the best fit using rice husk as indicated by their correlation coefficient (R2) of 0.332, 0.041 and 0.556 for Mn(II), Zn(II) and Pb (II) respectively. The study also showed that groundnut husk and rice husk can be efficiently used as low cost alternative for removal of Mn2+, Zn2+ and Pb2+.

Effect of Operational Parameters in the Continuous Anaerobic Fermentation of Cheese Whey on Titers, Yields, Productivities, and Microbial Community Structures

Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed bed bioreactor was set up to digest anaerobically, under an acidogenic condition, a water solution of a cheese whey powder. Batch tests pointed out that the whole VFAs production process occurred via two sequential phases: (a) conversion of lactose into lactic acid and (b) conversion of lactic acid into a mixture of VFAs. Furthermore, the same tests showed that the ceramic material Vukopor S10 can be used as an effective support for cell immobilization in anaerobic fermentation processes. The effect of the hydraulic retention time (HRT) and organic loading rate (OLR) were then studied in a benchtop bioreactor operated continuously. By a HRT of 6 days, ORL of 4.2 g/L/d, and pH 5.8–6, 16 g·L–1 of total VFAs were produced, with a yield higher than 75% (CmolVFAs·Cmollactose–1). Characterization with Illumina-based sequencing suggested that high VFAs productivities were obtained when microbial community structures ...

Removal of aqueous benzene in the immobilized batch and continuous packed bed bioreactor by isolated Bacillus sp. M1

Benzene biodegradation was studied in batch and continuous packed bed bioreactors using polyurethane foam (PUF) as packing media byisolated Bacillus sp. M1. The values of optimized process parameters were found to be 800 × 106 CFU·mL−1, 400 mg·L−1, 7.0 and 37 °C forinoculum size, substrate concentration, pH and temperature respectively. Continuous packed bed bioreactor (CPBBR) was operated and monitoredfor 69 days on laboratory scale at various flow rates (10–60 mL·h−1). The steady state removal efficiency was observed more than 90% up to theinlet load of 288 mg·L−1.d−1 and elimination capacity was found to be 91.2–266.4 mg·L−1·day−1. Monod growth model was applied for the removalof benzene and values were found to be (Ks: 215.07 mg·L−1; μmax: 0.314 day−1).

Performance evaluation of Malathion biodegradation in batch and continuous packed bed bioreactor (PBBR)

The aim of this work was to study the biodegradation of Malathion in batch and continuous packed bed (Polyurethane foam; PUF) bioreactor (PBBR). After 10days, 89% Malathion removal was observed in batch PBBR. Continuous PBBR was operated at various flow rates (5–30mL/h) under optimum condition over a period of 75days. Inlet loading rates and elimination capacities were observed in the range of 36–216 and 7.20–145.4mg/L/day with an average removal efficiency of more than 90% under steady state conditions. GC/MS analysis confirms phosphorodithionicacid,O,O,S-trimethylester and diethylmercaptosuccinate as metabolites.Biodegradation of Malathion under inhibitory and non-inhibitory conditions was studied using Monod and Andrew-Haldane models and the kinetic constants were calculated and found to be μmax: 0.271 per day; Ks: 126.3mg/L using Monod and μmax: 0.315 per day; Ks: 151.32mg/L; Ki: 594.75mg/L using Andrew-Haldane models.

Continuous generation of fructose from Taraxacum officinale tap root extract and inulin by immobilized inulinase in a packed-bed reactor

Abstract Production of exo-inulinase from newly isolated Aspergillus niger was statistically optimized using dandelion tap root extract (% fresh w/v) resulting in a ~2.5 fold (2337 nkat/ml) enhancement. Exo-inulinase (1166 nkat/mg) immobilized in Ca-alginate beads was used for continuous generation of fructose from crude inulin extracted from Taraxacum officinale (dandelion) and chicory juice. Immobilized enzyme was optimally active at 50 °C and pH 5.0 and the kinetic parameters evaluated were 3.74 mM ( K m ) and 1.62 µm/min ( V max ). Continuous generation of fructose syrup from low-cost dandelion root extract and chicory inulin using a packed bed bioreactor prepared with exo-inulinase immobilized in alginate beads was demonstrated. Successive degradation of dandelion oligosaccharides and fructans to pure fructose was observed over 30 days period. The bioreactor had a half-life of 15 days and more than 90% (w/w) yield of fructose was observed. The study demonstrated use of a fructan-rich common weed for continuous production of fructose.

Removal of aqueous benzene in the immobilized batch and continuous packed bed bioreactor by isolated Bacillus sp. M1

Abstract Benzene biodegradation was studied in batch and continuous packed bed bioreactors using polyurethane foam (PUF) as packing media by isolated Bacillus sp. M1. The values of optimized process parameters were found to be 800 × 10 6 CFU⋅mL −1 , 400 mg⋅L −1 , 7.0 and 37 °C for inoculum size, substrate concentration, pH and temperature respectively. Continuous packed bed bioreactor (CPBBR) was operated and monitored for 69 days on laboratory scale at various flow rates (10–60 mL⋅h −1 ). The steady state removal efficiency was observed more than 90% up to the inlet load of 288 mg⋅L −1 .d −1 and elimination capacity was found to be 91.2–266.4 mg⋅L −1 ⋅day −1 . Monod growth model was applied for the removal of benzene and values were found to be (K s : 215.07 mg⋅L −1 ; µ max : 0.314 day −1 ).

Effects of different carriers on biogas production and microbial community structure during anaerobic digestion of cassava ethanol wastewater

ABSTRACTIn this study, an anaerobic bioreactor (AB) with no added fillers (ABWF), a packed-bed bioreactor with a porous ceramic filler (ABCF), and another packed-bed bioreactor filled with graphite felt (ABGF) were established for anaerobic digestion of cassava ethanol wastewater. The results showed that ABCF exhibited excellent wastewater treatment performance in a stable process that was superior to ABWF and ABGF, with the following characteristics: a high chemical oxygen demand removal efficiency of 98.06% and maximum biogas production of 3200 mL/d at a total reactor volume of 3.46 L. Illumina MiSeq sequencing analysis revealed that differences existed among the microbial communities of the three ABs that were in accordance with the operational characteristics. The ABCF system displayed maximum bacterial diversity, whereas the ABWF system exhibited moderate richness and the ABGF system possessed the lowest species richness. The ABCF system was more stable than the ABWF and ABGF systems during anaerobic digestion of cassava ethanol wastewater. Different functional microbial communities that are responsible for the degradation of certain compounds were also identified in the ABCF and ABGF systems. Our results demonstrate that ceramic materials should be considered an appropriate support for the immobilization of cells.

Production of precursors for anti-Alzheimer drugs: Asymmetric bioreduction in a packed-bed bioreactor using immobilized D. carota cells

ABSTRACT(S)-1-Phenylethanol derivatives, which are the precursors of many pharmacological products, have also been used as anti-Alzheimer drugs. Bioreduction experiments were performed in a batch and packed-bed bioreactor. Then, the kinetics constants were determined by examining the reaction kinetics in the batch system with free and immobilized carrot cells. Also, the effective diffusion coefficient (De) of acetophenone in calcium alginate-immobilized carrot cells was investigated. Kinetics constants for free cells, which are intrinsic values, are reaction rate Vmax = 0.052 mmol L−1 min−1, and constants of the Michaelis–Menten KM = 2.31 mmol L−1. Kinetics constants for immobilized cells, which are considered apparent values, are Vmax, app = 0.0407 mmol L−1 min−1, KM, app = 3.0472 mmol L−1 for 2 mm bead diameter, and Vmax, app = 0.0453 mmol L−1 min−1, KM, app = 4.9383 mmol L−1 for 3 mm bead diameter. Average value of effective diffusion coefficient of acetophenone in immobilized beads was determined as 1.97 × 10−6 cm2 s−1. Using immobilized carrot cells in an up-flow packed-bed reactor, continuous production of (S)-1-phenylethanol through asymmetric bioreduction of acetophenone was performed. The effects of the residence time and concentrations of substrate were investigated at pH 7.6 and 33°C. Enantiomerically pure (S)-1-phenylethanol (ee > 99%) was produced with 75% conversion at 4-hr residence time.

Lipase immobilized on rosin-based functional polymers as a biocatalyst for the synthesis of ethyl dodecanoate

Rosin is a renewable, solid, resinous material that has been widely used because of its excellent performance and availability. In this work, we synthesized two rosin-based functional polymers (PFME and PMMEag) bearing aldehyde groups by suspension polymerization, with ethylene glycol maleic rosinate acrylate (EGMRA) as a cross-linker, for the immobilization of porcine pancreas lipase. The effects of immobilization conditions, temperature, and pH on several factors, including enzyme activity, reusability of the immobilized lipase, and optimal parameters of the bioreactor, were studied. PMMEag was found to be the optimal choice for lipase immobilization. The optimal immobilization time, temperature, and enzyme loading ratios of lipase immobilized on PMMEag were 150min, 20°C, and 10%, respectively. Lipase immobilized on PMMEag carriers were stable at high temperatures and over a broader pH range, and PMMEag-L retained 98% of its relative activity after 10 cycles of operation. The immobilized lipase (PMMEag-L) was operated in a packed-bed bioreactor for the synthesis of ethyl dodecanoate. Under the optimized conditions, the conversion rate reached 18.3%. These results show that rosin-based functional polymers are promising carriers for the immobilization of lipase.

Bioreactor Analysis for the Corn-Cob Valorization in the Xylanase Production

To achieve the optimization of the solid-state fermentation (SSF) processes where agro-industrial wastes are used, a better understanding of biological aspects (mathematical modeling) are needed, due the heterogeneity of these materials. The purpose of this study was to compare the effect of the bioreactor arrangement (Tray and Column) in the synthesis of xylanase by Rhizomucor pusillus strain in SSF process. Fermentation process was realized in both, tray and column bioreactors, using corn-cob (CC) as a carrier-substrate. Tray bioreactor and packed-bed bioreactor, containing fungal spores, 3 g of CC as substrate and support, and 8 mL of minimum Czapek-Dox culture medium; were incubated at 50 °C for 5 days. Maximal specific growth rate (μ max), maximal biomass level (X max), product/biomass yield (α) and secondary coefficient of product formation or destruction (β) were estimated by mathematical models. High value of xylanase enzyme activity (587.6 U/gds) was found in the column bioreactor. The logistic equation for cell growth and Luedeking-Piret equation for xylanase production could satisfactorily simulate the bioreactors’ kinetics data. The production of xylanase by Rhizomucor pusillus SOC-4A is affected by the type of bioreactor. Data showed that the most efficient bioreactor in production of the xylanase enzyme is the column bioreactor.

Ethanol production by solid-state saccharification and fermentation in a packed-bed bioreactor

In this work was presented a sequential strategy to optimize and scale-up the production of ethanol by solid-state saccharification and fermentation using rice bran as substrate. In the first step, fermentation was carried out in Erlenmeyers to study the influence of eight variables by means of a Plackett Burman design. After the choice of most significant ones, a central composite rotational design (CCRD) for three independent variables (rice bran concentration, moisture content and inoculum size) was conceived to optimize the ethanol production in a packed-bed bioreactor. From Erlenmeyers to packed bed bioreactor the process was scaled-up 10 times. Maximum ethanol production in the packed-bed bioreactor was 135 ± 10.8 g kg−1 at inoculum size, rice bran concentration and moisture content of 10% v/v, 62.5% w/w and 65% w/w, respectively. The ethanol yield obtained in the packed-bed bioreactor was similar to that in the erlenmeyers flasks (138.7 g kg−1), validating the strategy adopted for optimization and scale-up.

Horseradish peroxidase-assisted approach to decolorize and detoxify dye pollutants in a packed bed bioreactor

In this study, horseradish peroxidase (HRP) was covalently immobilized on the calcium-alginate support using glutaraldehyde (GA) as a cross-linking reagent for detoxification and degradation of synthetic dyes. Immobilization procedure furnished significant immobilization efficiency (86.27 ± 3.43%) along with apparent and relative activity of 24.39 ± 1.03 U/g and 84.97 ± 3.54%, respectively, for immobilized-HRP. In comparison to free-state, immobilized-HRP catalyzed the substrate oxidation reaction in a slightly acidic and wider temperature range, with an optimum at 60 °C. After 10 and 60 min of incubation at 60 °C, the immobilized-HRP displayed 99.0% and 89.0% of residual activities, whereas the free counterpart retained only 34.0% and 18.0% of residual activities, respectively. Moreover, the immobilized-HRP showed potential efficiency for the decolorization of dyes in sequential dye-decolorizing batch reactions. Cytotoxicity analysis using a plant bioassay and acute test demonstrated that the Ca-alginate immobilized-HRP may effectively be used for detoxification of dyes and has a great potential for large-scale environmental remediation.

Biodegradation of 2-naphthalensulfonic acid polymers by white-rot fungi: Scale-up into non-sterile packed bed bioreactors

This paper presents a first scale up under non-sterile conditions of the biodegradation process of 2-naphthalensulfonic acid polymers (NSAP) contained in a petrochemical wastewater by two white-rot fungi (Bjerkandera adusta and Pleurotus ostreatus). The biodegradation experiment was conducted first in flasks and then in packed-bed bioreactors filled with inert and biodegradable carriers (straw), the latter acting as both physical support and carbon source. Reactor inoculated with P. ostreatus attached on straw worked under non-sterile conditions for three months showing 30 ± 5% NSAP degradation. Respirometric tests showed that the fungal treatment was also able to significantly increase the biodegradable fraction of the wastewater COD, which rose from 9% to 40%. It was observed that the fungal degradation of the straw in the bed releases non-biodegradable by-products. Taking into account this contribution to nbCOD, the combined treatment of fungi and activated sludge could theoretically be able to reduce the original COD by up to 73%.

Treatment of tetrathionate effluents by continuous oxidation in a flooded packed-bed bioreactor

Thiosalts are compounds commonly present in process plant liquor for the concentration of metal sulphide ores by milling and flotation. Since thiosalts are metastable species that are oxidized to sulphuric acid as an end product, they cannot be discharged nor recycled into the process. Therefore, the development of a cost-effective process for the treatment of these effluents is necessary. In this paper, the continuous bio-oxidation of tetrathionate is carried out in a flooded packed-bed reactor by an immobilized microbial consortium. Batch tests show that the initial tetrathionate concentration and pH slightly affect the tetrathionate bio-oxidation process in the ranges 3 to 5g/L and 1.5 to 2, respectively. The specific bio-oxidation rate is 0.08h−1. Only sulphate ions and protons have been detected as end products. For the starting up of the bioreactor, a new method of biofilm formation for tetrathionate bio-oxidation is implemented. The maximum bio-oxidation rate in continuous operation is 0.415gh−1 (0.830kgh−1m−3). The biofilm was stable for the whole period studied, i.e. 35days. These results indicate that a flooded packed-bed reactor is an interesting option from an economic point of view for the treatment of waters contaminated by thiosalts.