Continuous Packed Bed Bioreactor Research Articles

Effect of Operational Variables on the Yield of Chemoenzymatic Oxidation of 2,5-Furandicarboxaldehyde to 2,5-Furandicarboxylic Acid in Fed-Batch and Continuous Packed-Bed Millibioreactor

This work explores for the first time the use of a fed-batch and continuous packed-bed millibioreactor for the chemoenzymatic oxidation of 2,5-furandicarboxaldehyde (DFF) to 2,5-furandicarboxylic acid (FDCA). Different operational variables were studied: temperature, substrate concentration, and flow rate using different reactors (batch, fed-batch, and a continuous packed-bed bioreactor). The best yield (100%) was achieved using the fed-batch reactor at an H2O2 flow rate of 3 µL/min with a substrate concentration (DFF) of 100 mM. Regarding the specific productivity, the highest values (>0.05 mg product/min g biocatalyst) were reached with the operation in the fed-batch bioreactor and the continuous packed-bed bioreactor. The yield of the biocatalyst decreased by 98% after the first reaction cycle during the operational stability tests, due to a substantial inactivation of the biocatalyst by H2O2 and peracid. In this study, it is possible to select the operational variables in fed-batch and continuous reactors for chemoenzymatic oxidation that can increase the yield and specific productivity; however, the stability of the biocatalyst should be improved in future research.

Model development and optimal control of a continuous packed bed bioreactor for the production of succinic acid

A dynamic model consisting of a system of partial differential equations, was created in order to describe and simulate the behaviour of a continuous immobilised-cell fermentation system for the production of succinic acid from glycerol. The model can confidently predict the steady state output of the process under a range of different initial and operating conditions. Moreover the model results, are verified by experimental results, further strengthening the credibility of the model. Then the constructed model was utilised to build a model reduction-based stochastic optimal control strategy for the complex bio-process. Proper Orthogonal Decomposition and artificial neural networks were employed to address the high dimensionality of the model, in a 2-step reduction scheme, and polynomial chaos expansion to address model uncertainty. Computational results show that the reduced model-based stochastic control policy can efficiently improve production satisfying process requirements for byproduct concentrations.

Polyurethane foam as biomass support for removal of thiosalts from flotation process water

Water recycling is a common practice in sulphide ore processing plants by flotation. Inherent thiosalts accumulation in process water often causes efficiency drop and environmental issues for wastewater discharging. Passive and active depuration methods have been applied for thiosalts removal and bio-oxidation in packed bed bioreactors can be considered the most promising option.In this work, polyurethane foam is for first time used as biomass support material in continuous bio-oxidation of thiosalts. Two columns, 15 and 197 cm in height and 8.4 cm in diameter, packed with 1 cm in edge length cubic particles were trialled. A new and fast start-up procedure was performed allowing to effectively operate them in less than seven days. Complete removal of thiosalts in real liquors were achieved with bio-oxidation rates close to 0.45 kg/hm3 and residence time lower than 7 h. Stability, robustness and versatility showed by the bioreactors allows to affirm that polyurethane foam is a suitable material as biomass support in continuous packed bed bioreactors for thiosalts bio-oxidation.

Three-dimensional CFD simulation of anaerobic reactions in a continuous packed-bed bioreactor

In this study, a lab-scale continuous packed-bed bioreactor with multi-sized distributed particles has been simulated in a structured layout using computational fluid dynamics. The goal was to achieve a well-estimated simple model which can describe the hydrodynamic regime of flow as well as mass transfer of species within the bioreactor. A MATLAB program was coded to create the packed-bed geometry by generating non-overlapping spherical particles. The flow hydrodynamics was assumed to be single-phase creeping flow regime (Stokes flow). The kinetic data of batch experiments at similar operating conditions were used to formulate the rate of anaerobic reactions. The anaerobic methanogenesis reactions were assumed to occur at the particle surfaces (on the biofilm). The bioreactor temperature was fixed at 37°C. The commercial software COMSOL Multiphysics 5.0 was employed to solve the governing equations. Velocity profiles and concentration distribution of volatile fatty acids (VFAs) are shown inside the packed-bed reactor. Simulation results were found to be in good agreement with the experimental data at various influent flow rates (23.8 – 43.5 mL/h) and various influent concentrations of VFAs (0.001 – 0.042 M). In all cases, the relative error was less than 15% which is acceptable. This proposed model is applicable for scale-up and optimization purposes as well as evaluation of other kinetic models.

Continuous Production of 2-Phenylethyl Acetate in a Solvent-Free System Using a Packed-Bed Reactor with Novozym® 435

2-Phenylethyl acetate (2-PEAc), a highly valued natural volatile ester, with a rose-like odor, is widely added in cosmetics, soaps, foods, and drinks to strengthen scent or flavour. Nowadays, 2-PEAc are commonly produced by chemical synthesis or extraction. Alternatively, biocatalysis is a potential method to replace chemical synthesis or extraction for the production of natural flavour. Continuous synthesis of 2-PEAc in a solvent-free system using a packed bed bioreactor through immobilized lipase-catalyzed transesterification of ethyl acetate (EA) with 2-phenethyl alcohol was studied. A Box–Behnken experimental design with three-level-three-factor, including 2-phenethyl alcohol (2-PE) concentration (100–500 mM), flow rate (1–5 mL min−1) and reaction temperature (45–65 °C), was selected to investigate their influence on the molar conversion of 2-PEAc. Then, response surface methodology and ridge max analysis were used to discuss in detail the optimal reaction conditions for the synthesis of 2-PEAc. The results indicated both 2-PE concentration and flow rate are significant factors in the molar conversion of 2-PEAc. Based on the ridge max analysis, the maximum molar conversion was 99.01 ± 0.09% under optimal conditions at a 2-PE concentration of 62.07 mM, a flow rate of 2.75 mL min−1, and a temperature of 54.03 °C, respectively. The continuous packed bed bioreactor showed good stability for 2-PEAc production, enabling operation for at least 72 h without a significant decrease of conversion.

Performance evaluation of a continuous packed bed bioreactor: Bio-kinetics and external mass transfer study.

The biodegradation of naphthalene using low-density polyethylene (LDPE) immobilized Exiguobacterium sp. RKS3 (MG696729) in a packed bed bioreactor (PBBR) was studied. The performance of a continuous PBBR was evaluated at different inlet flow rates (IFRs) (20-100mL/h) under 64 days of operation. The maximum naphthalene removal efficiency (RE) was found at low IFR, and it further decreased with increasing IFRs. In a continuous PBBR, the external mass transfer (EMT) aspect was analysed at various IFRs, and experimental data were interrelated between Colburn factor (JD) and Reynolds number (NRe) as [Formula: see text] . A new correlation [Formula: see text] was obtained to predict the EMT aspect of naphthalene biodegradation. Andrew-Haldane model was used to evaluate the bio-kinetic parameters of naphthalene degradation, and kinetic constant νmax, Js, and Ji were found as 0.386 per day, 13.6mg/L, and 20.54mg/L, respectively.

Synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on a magnetic polymer support in continuous flow.

This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50°C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4-4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98gL-1 which corresponded to ester productivity of 23.16 ± 0.49mmolg-1L-1h-1. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063h. A model based on the ping-pong Bi-Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R2 = 0.9310-0.9952).

Biodegradation of fluorene by neoteric LDPE immobilized Pseudomonas pseudoalcaligenes NRSS3 in a packed bed bioreactor and analysis of external mass transfer correlation

Abstract The main objective of this study was to analyze the effects of the external mass transfer on fluorene (polycyclic aromatic hydrocarbon) degradation with immobilized LDPE (low-density polyethylene) in a packed bed bioreactor (PBBR). A most effective bacterial species Pseudomonas pseudoalcaligenes NRSS3 (MF9921912) was isolated from petroleum contaminated soil and immobilized on LDPE. The effect of different flow rates (10, 20, 30, 40, and 50 mL/h) on the degradation of fluorene was studied in a continuous PBBR. The overall removal efficiency of fluorene was found to be 88.49% in PBBR. The rate constants were estimated at different flow rates. The effect of flow rates on external mass transfer was also studied and correlated with the obtained experimental data. A correlation between Reynolds number (NRe) and Colburn factor (JD) ( J D = K N R e ( n - 1 ) ) was used to study the mass transfer aspects. The model was tested with various values of K, and n and based on experimental data, a new correlation J D = 5.71 N R e - 0.2 was obtained to predict the removal of fluorene in PBBR. The intermediate metabolites of the degraded sample were also analyzed by GC–MS and found that 1,2-benzenedicarboxylic acid and catechol were formed during the biodegradation process.

Novel investigation of the performance of continuous packed bed bioreactor (CPBBR) by isolated Bacillus sp. M4 and proteomic study

The present study reveals the benzene degrading potential of bacterial species isolated from petroleum contaminated soil. Genomic analysis suggests that Bacillus sp. M4 was found to be dominating species. The process parameters were optimized and found to be pH 7.0 ± 0.2, temperature 32 ± 5 °C, immobilization time (20 days) and benzene concentration 400 mg/L. The maximum removal efficiency of benzene was calculated and found to be 93.13% at elimination capacity156 (mg/L/day) and inlet loading rate 192 (mg/L/day) achieved in 54th days of operation. In the study, the residual metabolites were analyzed by GC/MS analysis and identified as benzene-1,2-diol. In order to identify the responsible protein involved in the process of benzene biodegradation The proteomic study was performed and proteins were identified by MALDI-TOF analysis. The molecular docking was confirmed by the benzene biodegradation.

Novel study on biodegradation of malathion and investigation of mass transfer correlation using alginate beads immobilized Bacillus sp. S4 in bioreactor

In this study the external mass transfer effects on the biodegradation of malathion were studied. The experiments were performed in continuous packed bed bioreactor packed with immobilized alginate beads. The isolated bacterial species Bacillus sp. S4 was encapsulated with alginate beds. The effect of inlet flow rate (5–20 mL/h) on biodegradation of malathion (300 mg/L) was examined. At different flow rates the biodegradation rate constants were calculated by assuming the first-order biodegradation kinetics. The possible degradation routes were proposed for malathion biodegradation. The external mass transfer coefficients for biodegradation of malathion were also investigated for different values of flow rate. The mass transfer effect was correlated with the model JD = K NRe−(1−n). The novel mass transfer correlation was found as JD = 5.7 NRe−0.40 in order to predict the experimental data accurately and the model were studied with different values of n and K. The developed model would be useful for the scale up of useful industrial bioreactors.

Bioremediation of Congo red dye in immobilized batch and continuous packed bed bioreactor by Brevibacillus parabrevis using coconut shell bio-char

In the present study, bacterial species capable of degrading colour waste were isolated from the water bodies located near the carpet cluster in the Bhadohi district of U.P., India. Among the isolated species best one was selected on the basis of its capability to degrade Congo red in batch experiments using NaCl-Yeast as the nutrient media and further it was identified as Brevibacillus parabrevis using 16S rDNA sequencing. The process parameters were optimized for maximum degradation in batch experiments and found out to be: Inoculum size: 3 ml, Temperature: 30 °C, Time: 6 days leading to a removal of 95.71% of dye sample. The experiment showed that bacteria immobilized with coconut shell biochar in continuous mode showed much better degradation than batch study without immobilization. The kinetics parameters μmax, Ks, and μmaxKs were found to be 0.461 per day, 39.44 mg/day, and 0.0117 L/mg/day using Monod model.

Design and Properties of an Immobilization Enzyme System for Inulin Conversion.

A commercial inulinase could convert inulin into fructose, which was optimized to be entrapped in the calcium alginate-gelatin beads with the immobilization yield of 86% for free inulinase activities. The optimum pH values and temperatures were 4.5 and 40°C for the free enzyme and 5.0-5.5 and 45-50°C for the immobilized enzyme. The kinetic parameters of V max and K m were 5.24μmol/min and 57.6mg/mL for the free inulinase and 4.32μmol/min and 65.8mg/mL for the immobilized inulinase, respectively. The immobilized enzyme retained 80% of its initial activities at 45°C for 4days, which could exhibit better thermal stability. The reuse of immobilized inulinase throughout the continuous batch operations was explored, which had better reusability of the immobilized biocatalyst. At the same time, the stability of immobilized enzyme in the continuous packed-bed bioreactor was estimated, which showed the better results and had its potential scale-up fructose production for inulin conversion.

Semi-pilot scale-up of a continuous packed-bed bioreactor system developed for the lipase-catalyzed production of pseudo-ceramides

Ceramides are sphingolipid compounds that are very attractive as active components in both the pharmaceutical and the cosmetic industries. In this study, the synthesis of 1- O ,3- N -diacyl 3-amino-1,2-propanediol-type pseudo-ceramides was developed at the semi-pilot scale, starting from a two-step continuous enzymatic process with immobilized Candida antarctica lipase B (Novozym ® 435) in a packed-bed bioreactor, previously optimized at the laboratory scale. This process involved the selective N -acylation of 3-amino-1,2-propanediol (step 1), followed by the selective O -acylation of the N -acyl 3-amino-1,2-propanediol synthesized in the first step, with various fatty acids as acyl donors, to produce N , O -diacyl 3-amino-1,2-propanediol-type pseudo-ceramides (step 2). Under partially optimized operating conditions, high synthesis yields and production rates were obtained, within the ranges 76–92% and 3.7–4.6 g h −1 (step 1), or 23–36% and 1–1.4 g h −1 (step 2), respectively, depending on the fatty acids used as acyl donors. The overall synthesis yields varied from 20 to 33%: the best yield was obtained using palmitic acid and lauric acid as first and second acyl donors, respectively. Together with the high production rates also obtained with these acyl donors, this confirms that this two-step process has great potential for the production of differently functionalized 1- O ,3- N -diacyl 3-amino-1,2-propanediol-type pseudo-ceramides on an industrial scale.

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.

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 ).

Synthesis of Lactose-Derived Nutraceuticals from Dairy Waste Whey—a Review

Due to stricter environmental legislation and implementation of the “waste valorization” concept, recycling of dairy effluent, whey, has drawn a considerable attention. The main constituent of whey is lactose, which is responsible for high biological oxygen demand (BOD) and chemical oxygen demand (COD) values. Therefore, without going to its direct disposal into aquatic system, synthesis of nutraceuticals from lactose is considered a commendable challenge. Lactose-derived nutraceuticals, such as galacto-oligosaccharide (GOS), lactulose, lactitol, lactosucrose, lactobionic acid, gluconic acid, lactone, and tagatose, have been synthesized through different chemical and biochemical reactions, such as hydrolysis, transgalactosylation, oxidation, reduction, isomerization, and hydrogenolysis, considering raw whey or isolated lactose as feedstock. Pure biocatalyst (enzyme) and inorganic catalyst have been used for the synthesis of lactose-based nutraceuticals by different types of operations, such as conventional batch and continuous bioreactors with free catalyst, continuous packed bed bioreactor with immobilized catalyst, moving bed reactor, and membrane-assigned bioreactor. Moreover, in many cases, lactose-based nutraceuticals (lactic acid, lactosucrose, lactobionic acid, gluconic acid, and tagatose) have been synthesized by microbial fermentation process. Free microbial cell in batch and continuous fermentor and whole cell immobilized packed bed bioreactor have been used for this purpose. This review presents and compares different process-related technological aspects for synthesis of lactose-derived nutraceuticals from whey.

Efficacy of Aspergillus sp. for degradation of chlorpyrifos in batch and continuous aerated packed bed bioreactors.

Aerobic biodegradation of chlorpyrifos (CP) by Aspergillus sp. was investigated in batch and continuous packed bed bioreactors. The optimal process parameters for achieving the maximum removal efficiency (RE), determined using a batch bioreactor packed with polyurethane foam pieces, were inoculum level: 2.5 mg (wet weight) mL(-1), pH 7.0, temperature 28 °C, DO 5.8 mg L(-1), and CP concentration 300 mg L(-1). The continuous packed bed bioreactor was operated at flow rates ranging from 10 to 40 mL h(-1) while keeping other parameters at their optimal level. Steady-state CP removal efficiencies greater than 85 % were obtained up to the inlet loading of 180 mg L(-1) d(-1). The continuous bioreactor behaved as a plug flow unit and was able to stabilize quickly after perturbation in the inlet loading.

Stability of immobilized Rhizomucor miehei lipase for the synthesis of pentyl octanoate in a continuous packed bed bioreactor

The enzymatic synthesis of organic compounds in continuous bioreactors is an efficient way to obtain industrially important chemicals. However, few works have focused on the study of the operational conditions and the bioprocess performance. In this work, the aliphatic ester pentyl octanoate was obtained by direct esterification using a continuous packed bed bioreactor containing the immobilized enzyme Lipozyme® RM IM as catalyst. Enzymatic deactivation was evaluated under different conditions for the operational parameters substrate/enzyme ratio (5.00, 1.67, 0.83 and 0.55 mmol substrate∙min-1∙g-1enzyme) and temperature (30, 40, 50 and 60 °C). The optimal condition was observed at 30 ºC, which gave the minimum enzymatic deactivation rate and the maximum conversion to the desired product, yielding approximately 60 mmols of ester for an enzyme loading of 0.5 g into the bioreactor. A first-order deactivation model showed good agreement with the experimental data.

Biodegradation of chlorpyrifos by Pseudomonas sp. in a continuous packed bed bioreactor

Biodegradation of chlorpyrifos (CP) by Pseudomonas (Iso 1) sp. was investigated in batch as well as continuous bioreactors packed with polyurethane foam pieces. The optimum process parameters for the maximum removal of CP, determined through batch experiments, were found to be: inoculum level, 300×106CfumL−1; CP concentration, 500mgL−1; pH 7.5; temperature, 37°C and DO, 5.5mgL−1. The continuous packed bed bioreactor was operated at various flow rates (10–40mLh−1) under the optimum conditions. The steady state CP removal efficiency of more than 91% was observed up to the inlet load of 300mgL−1d−1. The bioreactor was sensitive to flow fluctuations but was able to recover its performance quickly and exhibited the normal plug-flow behavior. Accumulation of TCP (3,5,6-trichloro-2-pyridinol) affected the reactor performance.