A study of butanol production in a batch oscillatory baffled bioreactor

PhD ThesisAs with many bioprocesses, the acetone-butanol-ethanol (ABE) fermentation faces a number of economic drawbacks when compared to the petrochemical route for butanol production. In the 1920s biobutanol was the second largest biotechnology industry, after bioethanol production. However it became difficult to compete against the petrochemical route for reasons including the low product butanol concentration, because of product inhibition resulted in low butanol productivity and due to slow fermentation and low ABE yields. These lead to uneconomical butanol recovery by the conventional method, distillation, due to the high degree of dilution. Recent interest in biobutanol as a biofuel has led to re-examination of ABE fermentation with the aim of improving solvent yield, volumetric productivity and final solvent concentration to reduce the cost of production and thereby produce biobutanol that is cost-competitive with the chemical synthesis butanol. ABE fermentations were carried out in an intensified plug flow reactor known as the batch oscillatory baffled bioreactor (BOBB). The “BOBB”s were designed and built for this project. The effect of oscillatory flow mixing on ABE fermentation was compared to that of conventional stirred tank reactors (STRs) at power densities in the range 0 to 1.14 Wm⁻³. The maximum butanol concentration in this range in a BOBB was 34% higher than the STR. Some increase in butanol productivity was also observed: 0.13 gL⁻¹h⁻¹ in BOBBs, compared to 0.11 gL⁻¹h⁻¹ in the STRs. It can be concluded that at similar power densities, BOBB fermentation shifts to solventogenesis earlier than in STRs, resulting in higher solvent productivity. It is hypothesised that the reason for early solventogenesis in the BOBB was the higher solvent-producing cell concentration, due to the more uniform shear field in the BOBB, so the cell would be less exposed to high shear thereby reducing the risk of cell lysis. Two-stage ABE fermentations in BOBB increased the butanol productivity by up to 37.5% over the one-stage fermentation. Butanol productivity was further increased by 97% when gas stripping was integrated to the two-stage ABE fermentation. While the one-stage fermentation integrated with gas stripping increased the butanol productivity by 69% to 0.12 gL⁻¹h⁻¹ (as opposed to 0.071 gL⁻¹h⁻¹ in a similar fermentation without gas stripping). A simple model to describe the one-stage at oscillatory Reynolds number (Re₀) 0 and 938, and the two-stage ABE fermentation in BOBB II was developed. The model summarizes the physiological aspects of growth and metabolite synthesis by Clostridium GBL1082. The prediction of the models were in good agreement with experimental results incorporating mixing (Re₀938) and moderately agreed with results from Re₀0 and the two-stage fermentation.Technology Strategy Board (TSB),The School of Chemical Engineering and Advanced Materials (CEAM), Newcastle University and Green Biologics Ltd: WH Partnership Ltd: The Malaysian Government, Ministry of Higher Education and University Malaysia, Pahang

A statistical study of factors affecting natural biovinegar fermentation from pineapple peel waste

The objective of this work was to screen and evaluate the significant parameter which affected the natural fermentation of pineapple biovinegar. In this work, peel waste from local breed pineapple (Royal Pepina) was fermented naturally to produce an aromatic biovinegar. Full factorial design of Design Expert® was used to develop a random experimental run in which six parameters were screened off. They were the fermentation temperature (27 – 50 °C), fermentation time (5 – 28 days), fermentation condition (anaerobic and aerobic), the addition of glucose (0 – 7 %), the addition of yeast (0 – 0.3 %), and peel waste condition (slurry & juice). Three parameters were identified as significant factors, which were the condition of fermentation, fermentation temperature, and addition of glucose. The ANOVA of the model was statistically significant with R2 of 0.9948. The pineapple biovinegar produced in this work contained 3.18 % reducing sugar, 1.03 % ethanol, 3.03 % acid, 0.61 % acetic acid, 1.43 mg equi. AA/100mL ascorbic acid, pH of 3.16, 4.0 % sucrose, 8.0 °Brix total soluble solid, and 82.06 % DPPH free-radical scavenging activity of antioxidant in biovinegar. This result stood second highest after apple cider biovinegar when compared to commercially available biovinegar

Optimization of process factor and characterization of vinegar-like beverage production via spontaneous fermentation from pineapple peel waste

A feasible approach to compensating for pineapple wastage is by utilizing the waste. In the present study, pineapple peels were subjected to spontaneous fermentation to produce a vinegar-like beverage. Based on the central composite design (CCD) approach, optimization of the process factor recorded a maximum total acid yield, Yp/s, and total acidity of 0.49 and 3.03%, respectively. Furthermore, the beverage possessed increased tartaric, citric, ascorbic, acetic, and ferulic acids at a maximum of 1.196%. The cytotoxicity activity toward the human colorectal adenocarcinoma cell line documented a half maximal inhibitory concentration (IC50) at 3.4% v/v of the beverage. This study showcased optimized vinegar-like beverage production by indigenous microorganisms (IMO) with pineapple peel. The beverage contained improved organic and phenolic acids contents and antioxidant potential, which could be employed as a possible human colorectal cancer cure

Performance of oscillatory flow reactor and stir tank reactor in solvent fermentation from palm oil mill effluent

Advance in mixing technology has developed a new way of mixing fluids by introducing an oscillatory motion to replace the conventional mechanical agitation or an air bubble displacement. This new way of mixing breakthrough has been implemented in an Oscillatory Flow Reactor (OFR). This research will be focus on the performance of OFR as a bioreactor by comparing with Stir Tank Reactor (STR), which is the traditional device in fermentation. The experimental work was conducted in an OFR and a STR with a working volume of 1.5 l. Solvent production strain, Clostridium acetobutylicum NCIMB 13357 was grown in OFR and STR, using fresh Palm Oil Mill Effluent (POME) as growth medium. All of the experiments were conducted anaerobically under batch mode for 72 hours at constant temperature of 35°C. Comparisons of the growth trend and solvent fermentation performance for both devices were investigated. Total solvents (acetone, butanol and ethanol) produced in an OFR was comparable with that of STR. Total solvents production in OFR is 1.8 times higher than that of STR resulted in total 1.6 g/l of solvents. The results of this investigation showed that OFR has an excellent potential as an alternative device in fermentation processes

Enhanced excretion of recombinant cyclodextrin glucanotransferase and cell stability of immobilized recombinant Escherichia coli by reducing tryptone concentration

BACKGROUND: Recombinant protein excretion has become a mainstream strategy in reducing downstream processing costs. However, recombinant protein excretion is often bottlenecked by cell lysis and plasmid stability. In the present study, recombinant Escherichia coli cell immobilization was performed on a hollow fiber membrane. Tryptone concentration in the expression medium (Super Optimal Broth), which was used as a nitrogen source, was varied between 5 and 20 g L−1 to enhance the excretion of recombinant cyclodextrin glucanotransferase (CGTase), plasmid stability, and resistance of cell lysis. RESULTS: The immobilized cells with 5 g L−1 concentration of tryptone improved the plasmid stability with 119% improvement and 69% reduction of cell lysis without remarkably altering the excretion of CGTase compared with the tryptone concentration of 20 g L−1. The immobilized cells showed a 2-fold increase in excretion of CGTase, a 45% reduction in cell lysis, and a 172% gain in plasmid stability in comparison with the free cells. Moreover, the doubling time increased to 58 and 5 h for the immobilized and free cells, respectively. The immobilized cells recorded 2301.62 U mL−1 of cumulative CGTase activity through seven fermentation cycles using the untreated membrane, marking their excellent reusability. CONCLUSION: This new technique of recombinant protein expression utilizing an immobilized cell system under low tryptone concentration is an outstanding approach to improve recombinant CGTase excretion and plasmid stability with low cell lysis

Pineapple enzyme: Beneficial poultry supplement

Pineapple waste have been reported to contain nutrients such as dietary fibres, sugars, proteins and minerals. These nurients could serve as a prominent source of growth factors to poultry. Hence, it can helps as an alternative to reduce poultry farmer’s costs to buy poultry feed

Improved heterocyclic aromatic hydrocarbon compound adsorption using functionalised rice husk biochar

Carbazole (CBZ) is a hazardous heterocyclic aromatic hydrocarbon (HAH) that pollutes water bodies, and the treatment remains a challenge due to its high persistence in the environment. This study chemically modified rice husk biochar (RHB) with starch derivative (DS) to develop an effective adsorbent. Thus, functionalised RHB with starch derivative (RHBDS) was synthesised to remove CBZ from synthetic wastewater. Based on a Box-Behnken design, the DS functionalisation optimisation was successfully performed. The parameters, including RHB mass of (5–10) g, DS concentration of (1–5)% w/v, and sonication period of (1–5) min, were analysed using Design Expert. These parameters were then utilised to investigate the optimal conditions (removal rate response and adsorption capacity) for the adsorbent. The removal rate and the adsorption capacity ranged from 83.85 to 98.94 % and 335.41 to 395.76 mg/g, respectively. Consequently, the RHB mass of 6.50 g, DS concentration of 1 % w/v, and sonication period of 5 min within the experimental domain exhibited the best conditions with desirability of 1.0. The 92.67 % removal rate and adsorption capacity of 370.59 mg/g were also obtained under optimal conditions. Compared to RHB, RHBDS demonstrated four times the adsorption capacity for the CBZ removal from synthetic water, which were 23.03 mg/g and 98.01 mg/g, respectively. Therefore, the RHBDS compound could be a promising adsorbent in removing CBZ from wastewater

Adsorption of fatty acid on beta-cyclodextrin functionalized cellulose nanofiber

Fatty acids in wastewater contribute to high chemical oxygen demand. The use of cellulose nanofiber (CNF) to adsorb the fatty acids is limited by its strong internal hydrogen bonding. This study aims to functionalize CNF with β-cyclodextrin (β-CD) and elucidate the adsorption behaviour which is yet to be explored. β-CD functionalized CNF (CNF/β-CD) was achieved by crosslinking of β-CD and citric acid. Functionalization using 7% (w/v) β-CD and 8% (w/v) citric acid enhanced mechanical properties by increasing its thermal decomposition. CNF/β-CD was more efficient in removing palmitic acid, showcased by double adsorption capacity of CNF/β-CD (33.14% removal) compared to CNF (15.62% removal). CNF/β-CD maintained its adsorption performance after five cycles compared to CNF, which reduced significantly after two cycles. At 25 °C, the adsorption reached equilibrium after 60 min, following a pseudo-second-order kinetic model. The intraparticle diffusion model suggested chemical adsorption and intraparticle interaction as the controlling steps in the adsorption process. The maximum adsorption capacity was 8349.23 mg g−1 and 10485.38 mg g−1 according to the Sips and Langmuir isotherm model, respectively. The adsorption was described as monolayer and endothermic, and it involved both a physisorption and chemisorption process. This is the first study to describe the adsorption behaviour of palmitic acid onto CNF/β-CD