Quantitative Determination of Glucose Transfer Between Cocurrent Laminar Water Streams in a H-Shaped Microchannel

To explore the applicability of a laminar fluid diffusion interface (LFDI) for the controlled feeding of microbioreactors, glucose diffusion experiments were carried out in a rounded H-shaped microstructure etched in a glass substrate. The diffusion channel of the microstructure had a length of 4 mm and a depth of 50 μm with a trapezoidal cross section with a width of 100 μm at the bottom and 200 μm at the surface of the channel. The microchannel was operated at residence times of less than 1 s ensuring high-mass-transfer rates. It was confirmed, both by microscopic observations as well as computational fluid dynamics (CFD) studies that the flow characteristics in the microchannel were fully laminar. Special attention was paid to flow splitting at the end of the channel, because the CFD simulations indicated that the performance of the device was sensitive to unequal flow splitting. The difference in outflow volume of the two streams was measured to be small (1.25% ± 0.6%). The measured glucose concentration in both exit ports at a fixed residence time was found to be stable in time and reproducible in multiple experiments. CFD simulation was shown to be a powerful tool for estimating the mass transfer in the LFDI, even at very short residence times. The results obtained in this work show the applicability of LFDI for the controlled diffusive supply of a solute to a water stream, with as possible application substrate and/or precursor feeding to microreactors

Bioprocess intensification: cases that (don’t) work

Development of affordable and low carbon biobased manufacturing depends critically on strategies that reduce cost and emission profiles. This paper indicates that efforts around the reduction of capital costs by intensification of process equipment need to be carefully weighed against the inherently fast increasing financial and climate costs of driving forces used for the intensification. The fundamental relation between capital expenditures (CAPEX) and operational expenditures (OPEX) of intensified and non-intensified biobased processes and their financial and climatic impacts are emphasized and provisionally explored for a few industrial processes. General learnings flag the importance in particular of OPEX minimisation for sustainable bio-economic development

Data and code belonging to "Effect of acetic acid release and pH on lignocellulosic biomass conversion by liquid hot water pretreatment "

This dataset is an integral part of the study "Effect of acetic acid release and pH on lignocellulosic biomass conversion by liquid hot water pretreatment ", for which a manuscript is ready for submission for publication. This study used partly already published experimental data for a model-based description of the system of study, and partly generated new experimental data. The following files contain details of the models and experiments such as described in the manuscript:   Referring to the paper to which these data and code belong:   1. Excel file "Figures_2_3_4.xlsx" generates Figures 2, 3 and 4. 2. Matlab file "Temperature_fitting_figure_1.m" generates Figure 1. 3. Matlab file "Final_pH_from_C0_KB.m” is used to generate Figure 2. 4. Matlab file “Kinetic_parameter_regression_autocatalytic.m” is used to generate Figure 3. 5. Matlab file “Kinetic_parameter_regression_not_ autocatalytic.m” is used to generate Figure 3. 6. Matlab file “Progress_curve_180_oC_typical exp.m” is used to generate Figure 4. 7. Excel file “Experimental_data_sorted” is called by items 3, 4 and 5. 8. Excel file “Experimental_data_180oC_1exp” is called by item 6. 9. Excel file “Experimental data with HAc initially added” contains source data for Tables 2 and 3, and Figure 6.  10. Text file “Supplementary Materials text file.pdf” contains minor calculations mentioned in Section 2 of the paper. </p

Perspectives for the microbial production of methyl propionate integrated with product recovery

A new approach was studied for bio-based production of methyl propionate, a precursor of methyl methacrylate. Recombinant E. coli cells were used to perform a cascade reaction in which 2-butanol is reduced to butanone using alcohol dehydrogenase, and butanone is oxidized to methyl propionate and ethyl acetate using a Baeyer- Villiger monooxygenase (BVMO). Product was removed by in situ stripping. The conversion was in line with a model comprising product formation and stripping kinetics. The maximum conversion rates were 1.14 g-butanone/( L h), 0.11 g-ethyl acetate/(L h), and 0.09 g-methyl propionate/(L h). The enzyme regioselectivity towards methyl propionate was 43% of total ester. Starting from biomass-based production of 2-butanol, full-scale ester production with conventional product purification was calculated to be competitive with petrochemical production if the monooxygenase activity and regioselectivity are enhanced, and the costs of bio-based 2-butanol are minimized

Development of a system for the on-line measurement of carbon dioxide production in microbioreactors; application to aerobic batch cultivations of Candida utilis

We developed and applied a conductometric method for the quantitative online measurement of the carbon dioxide (CO2) production during batch cultivations of Candida utilis on a 100-μL scale. The applied method for the CO2 measurement consisted of absorption of the produced CO2 from the exhaust gas of the microbioreactor in an alkali solution, of which the conductivity was measured on-line. The measured conductivity change of the alkali solution showed a linear relation with the total amount of CO2 absorbed. After calibration of the CO2 measurement system, it was connected to a well of a 96-well microtiter plate. The mixing in the well was achieved by a magnetic stirrer. Using online measurement of the CO2 production during the cultivation, we show reproducible exponential batch growth of C. utilis on a 100-μL scale. The CO2 production measurements obtained from the microcultivation were compared with the CO2 production measurement in a 4-L bioreactor equipped with a conventional off-gas analyzer. The measurements showed that on-line measurement of the CO2 production rate in microbioreactors can provide essential data for quantitative physiological studies and provide better understanding of microscale cultivations

Subcritical CO2 shows no effect on liquid hot water pretreatment of poplar wood

Pretreatment of lignocellulosic biomass is required for many biorefinery processes. Previous studies have described hydrolysis of hemicelluloses by using liquid hot water (LHW) pretreatment. We evaluated the effect of carbonic acid originating from pressurized carbon dioxide during LHW pretreatment of poplar. The conditions applied covered temperatures from 120 to 200 °C, pretreatment times from 5 to 240 min and pressures from 1.0 to 2.2 MPa CO2 or N2. The pressure and the type of gas (CO2 or N2) did not have an effect on production of acetic acid, which functioned as a marker of progress of biomass hydrolysis. Results suggested that the presence of carbonic acid in the process does not significantly contribute to acidification. Deacetylation of lignocellulosic biomass can be achieved by LHW pretreatment irrespective of pressure and of gas type used, at the conditions tested

Aerobic batch cultivation in micro bioreactor with integrated electrochemical sensor array

Aerobic batch cultivations of Candida utilis were carried out in two micro bioreactors with a working volume of 100 μL operated in parallel. The dimensions of the micro bioreactors were similar as the wells in a 96-well microtiter plate, to preserve compatibility with the current high-throughput cultivation systems. Each micro bioreactor was equipped with an electrochemical sensor array for the online measurement of temperature, pH, dissolved oxygen, and viable biomass concentration. Furthermore, the CO2 production rate was obtained from the online measurement of cumulative CO2 production during the cultivation. The online data obtained by the sensor array and the CO2 production measurements appeared to be very reproducible for all batch cultivations performed and were highly comparable to measurement results obtained during a similar aerobic batch cultivation carried out in a conventional 4L bench-scale bioreactor. Although the sensor chip certainly needs further improvement on some points, this work clearly shows the applicability of electrochemical sensor arrays for the monitoring of parallel micro-scale fermentations, e.g. using the 96-well microtiterplate format

Mass transfer limitations in binderless ZSM-5 zeolite granules during adsorption of flavour compounds from aqueous streams

BACKGROUND: Recently, a new process concept has been proposed to selectively adsorb wort offflavours, i.e. aldehydes, from alcohol-free beers with hydrophobic zeolites. RESULTS: In this work, we investigated the uptake of a mixture of wort flavour compounds (2-methylpropanal, 2-methylbutanal, 3methylbutanal, furfural and methional), from a model solution onto binderless, hydrophobic ZSM-5 zeolite granules in order to quantify mass transfer parameters and identify bottlenecks. Subsequently, the homogenous solid diffusion model was employed to regress the effective diffusion coefficients for each molecule and experimental condition, which ranged between 10-15 and 10-13 m2/s, indicating strong intraparticle mass transfer limitation. Furthermore, it was found that the effective diffusion coefficient is inversely correlated to the molecules’ hydrophobicity, expressed as the logD value and its isotherm affinity constant. CONCLUSION: These results give valuable insight to design and improved adsorbent material and an off-flavour removal unit for industrial scale

Techno-economic assessment of heterotrophic microalgae biodiesel production integrated with a sugarcane bio-refinery

The use of diesel fuel in crop and transportation operations is responsible for one third of the carbon emissions in sugarcane biorefineries. A possible solution is to replace it with biodiesel from lipids, directly produced from sugarcane by highly productive heterotrophic microalgae. In this study a heterotrophic microalgae biodiesel plant, integrated with a typical Brazilian sugarcane bio-refinery, was designed and evaluated. Molasses, steam, and electricity from sugarcane processing were used as inputs for microalgae production. For a non-integrated plant, the production cost of the microalgae biodiesel was estimated at 2.51 and 2.27 $/liter for fed-batch and continuous processes, respectively. Equipment for cultivation and carbon sources was the highest cost affecting the financial feasibility of the proposed design. For the integrated plant, at present ethanol and biodiesel selling prices, the profitability would be lower than a first-generation sugarcane bio-refinery using fossil diesel fuel for its operations. However, the CO2 emissions would be reduced by up to 50000 ×103 kg per year at a cost of$83 10−3 kg−1 CO2-eq. If carbon credits are considered, the process becomes economically profitable even at present fuel prices

Microbial advanced biofuels production: overcoming emulsification challenges for large-scale operation

Isoprenoids and alkanes produced and secreted by microorganisms are emerging as an alternative biofuel for diesel and jet fuel replacements. In a similar way as for other bioprocesses comprising an organic liquid phase, the presence of microorganisms, medium composition, and process conditions may result in emulsion formation during fermentation, hindering product recovery. At the same time, a low-cost production process overcoming this challenge is required to make these advanced biofuels a feasible alternative. We review the main mechanisms and causes of emulsion formation during fermentation, because a better understanding on the microscale can give insights into how to improve large-scale processes and the process technology options that can address these challenges324221229FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2012/14003-9; 2011/51707-