Continuous production of cellulose acetate microspheres for textile impregnation using a mesostructured reactor

Cellulose - In this work, the emulsion step of a previously reported batch formulation, for production of cellulose acetate (CA) microspheres, is transposed to continuous mode using the NETmix...     

Increase of biogas production from pretreated hay and leaves using wood-rotting fungi

Wood-decaying mushrooms can be applied for the pretreatment of lignocellulosic substrates such as leaves, hay and straw. The use of wood-decaying fungus Auricularia auricula-judae for the decomposition of sweet chestnut (Castanea sativa) leaves and hay is discussed in the proposed paper. Such pretreated substrate was employed in the anaerobic processes for biogas production. Comparison of pretreated and non-pretreated substrate revealed that an increase of 15 % in the biogas production can be achieved using the pretreated substrate. Composition of organic compounds in the sludge during the anaerobic process was identified by HPLC. The obtained results show that the utilization of pretreated leaves and hay leads to a gradual increase of the concentration of formic, acetic, and volatile fatty acids as well as to the formation of some aldehydes, ketones, and alcohols.     

Continuous production of lactic acid from glucose and lactose in a cell-recycle reactor

Growth and lactic acid production ofLactobacillus delbreuckii were compared using glucose and lactose as carbon sources. A continuous-flow stirred-tank fermenter was coupled with a cross-flow filtration unit to permit operation at high-cell concentrations. At steady state, yeast extract requirements for lactic-acid production were lower when glucose was used as a substrate than with lactose fermentation. Once steady state was obtained, with glucose feed, it was possible to lower the yeast extract concentration without affecting biomass concentration and lactic acid production. The lacticacid concentration that inhibited cell growth and lactic acid production was found to depend on the choice of a carbon substrate.     

Continuous production of lactic acid in a cell recycle reactor

The production of lactic acid from glucose has been demonstrated using a CSTR (continuous stirred-tank reactor) with cell recycle. Studies were conducted withLactobacillus delbrueckii at a fermentation temperature of 42°C and a pH of 6.25. A cell density of 140 g dry weight/L and a volumetric productivity of 150 g/L.h, with complete glucose consumption, were obtained. It was not possible to obtain a lactic acid concentration above 60 g/L because of product inhibition. A cell purge was not necessary to maintain high viability bacteria culture or to obtain a steady state. At steady state the net cell growth appeared to be negligible. The specific glucose consumption for cell maintenance was 0.33 g glucose/g cells-h.     

Anaerobic baffled reactor treatment of biodiesel-processing wastewater with high strength of methanol and glycerol: reactor performance and biogas production

Biodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m⁻³ d⁻¹ to 3.0 kg m⁻³ d⁻¹ of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic baffled reactor operated at 1.5 kg m⁻³ d⁻¹ of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m⁻³ d⁻¹ of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable for methanogenesis. The biogas production rate was 12 L d⁻¹ and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally. A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external surface of the granular sludge was Methanosarcina.     

Semicontinuous production of lactic acid from cheese whey using integrated membrane reactor

Semicontinuous production of lactic acid from cheese whey using free cells of Bifidobacterium longum with and without nanofiltration was studied. For the semicontinuous fermentation without membrane separation, the lactic acid productivity of the second and third runs is much lower than the first run. The semicontinuous fermentation with nanoseparation was run semicontinuously for 72 h with lactic acid to be harvested every 24 h using a nanofiltration membrane unit. The cells and unutilized lactose were kept in the reactor and mixed with newly added cheese whey in the subsequent runs. Slight increase in the lactic acid productivity was observed in the second and third runs during the semicontinuous fermentation with nanofiltration. It can be concluded that nanoseparation could improve the lactic acid productivity of the semicontinuous fermentation process.     

Pure hydrogen production from methylcyclohexane using a new high performance membrane reactor

A high efficiency membrane reactor (Pd based) has been developed for hydrogen generation from methylcyclohexane, which is able to produce a pure hydrogen stream with a reaction yield close to 100%.     

Continuous production of Cu2ZnSnS4 nanocrystals in a flow reactor

A procedure for the continuous production of Cu(2)ZnSnS(4) (CZTS) nanoparticles with controlled composition is presented. CZTS nanoparticles were prepared through the reaction of the metals' amino complexes with elemental sulfur in a continuous-flow reactor at moderate temperatures (300-330 °C). High-resolution transmission electron microscopy and X-ray diffraction analysis showed the nanocrystals to have a crystallographic structure compatible with that of the kesterite. Chemical characterization of the materials showed the presence of the four elements in each individual nanocrystal. Composition control was achieved by adjusting the solution flow rate through the reactor and the proper choice of the nominal precursor concentration within the flowing solution. Single-particle analysis revealed a composition distribution within each sample, which was optimized at the highest synthesis temperatures used.     

Effects of hemicellulose and lignin on enzymatic hydrolysis of cellulose from dairy manure

This study focused on the effect of hemicellulose and lignin on enzymatic hydrolysis of dairy manure and hydrolysis process optimization to improve sugar yield. It was found that hemicellulose and lignin in dairy manure, similar to their role in other lignocellulosic material, were major resistive factors to enzymatic hydrolysis and that the removal of either of them, or for best performance, both of them, improved the enzymatic hydrolysis of manure cellulose. This result combined with scanning electron microscope (SEM) pictures further proved that the accessibility of cellulose to cellulase was the most important feature to the hydrolysis. Quantitatively, fed-batch enzymatic hydrolysis of fiber without lignin and hemicellulose had a high glucose yield of 52% with respect to the glucose concentration of 17 g/L at a total enzyme loading of 1300 FPU/L and reaction time of 160 h, which was better than corresponding batch enzymatic hydrolysis.     

Microfibrillated cellulose and cellulose nanopaper from Miscanthus biogas production residue

The feasibility of the isolation of microfibrillated cellulose (MFC) from the fibrous residue of the production of biogas from Miscanthus straw was investigated. Studying two variants of continuous anaerobic fermentation carried out at mesophilic and thermophilic conditions, respectively, MFC was obtained after extensive extraction of non-cellulosic compounds and mechanical fibrillation. MFC crystallinity and molar mass were drastically decreased in biogas residue with increasing temperature in processing. Nonetheless, nanopaper produced from all variants showed acceptable mechanical performance considering its significantly degraded structure. High failure strain at low density is of particular interest for the thermophilic variant. Infrared spectroscopy indicates changes in surface chemistry of the thermophilic variant, which may explain its peculiar tensile properties. Production of fibrillated cellulose from biogas residue is suggested as highly interesting route for the generation of additional value from bioenergy processes.     

Proteomic profiling of an undefined microbial consortium cultured in fermented dairy manure: Methods development

The production of polyhydroxyalkanoates (PHA; bioplastics) from waste or surplus feedstocks using mixed microbial consortia (MMC) and aerobic dynamic feeding (ADF) is a growing field within mixed culture biotechnology. This study aimed to optimize a 2DE workflow to investigate the proteome dynamics of an MMC synthesizing PHA from fermented dairy manure. To mitigate the challenges posed to effective 2DE by this complex sample matrix, the bacterial biomass was purified using Accudenz gradient centrifugation (AGC) before protein extraction. The optimized 2DE method yielded high‐quality gels suitable for quantitative comparative analysis and subsequent protein identification by LC‐MS/MS. The optimized 2DE method could be adapted to other proteomic investigations involving MMC in complex organic or environmental matrices.     

Feasibility of treating swine manure in an anaerobic sequencing batch biofilm reactor with mechanical stirring

Anaerobic sequencing batch reactors containing granular or flocculent biomass have been employed successfully in the treatment of piggery wastewater. However, the studies in which these reactors were employed did not focus specifically on accelerating the hydrolysis step, even though the degradation of this chemical oxygen demand (COD) fraction is likely to be the limiting step in many investigations of this type of wastewater. The mechanically stirred anaerobic sequencing batch biofilm reactor offers an alternative for hastening the hydrolysis step, because mechanical agitation can help to speed up the reduction of particle sizes in the fraction of particulate organic matter. In the present study, a 4.5-L reactor was operated at 30°C, with biomass immobilized on cubic polyurethane foam matrices (1 cm of side) and mechanical stirring provided by three flat-blade turbines (6 cm) at agitation rates varying from 0 to 500 rpm. The reactor was operated to treat diluted swine waste, and mechanical stirring efficiently improved degradation of the suspended COD. The operational data indicate that the reactor remained stable during the testing period. After 2 h of operation at 500 rpm, the suspended COD decreased by about 65% (from 1500 to 380 mg/L). Apparent kinetic constants were also calculated by modified first-order expressions.     

Continuous production of butanol from starch-based packing peanuts

Acetone, butanol, ethanol (ABE, or solvents) were produced from starch-based packing peanuts in batch and continuous reactors. In a batch reactor, 18.9 g/L of total ABE was produced from 80 g/L packing peanuts in 110 h of fermentation. The initial and final starch concentrations were 69.6 and 11.1 g/L, respectively. In this fermentation, ABE yield and productivity of 0.32 and 0.17 g/(L·h) were obtained, respectively. Compared to the batch fermentation, continuous fermentation of 40 g/L of starch-based packing peanuts in P2 medium resulted in a maximum solvent production of 8.4 g/L at a dilution rate of 0.033 h⁻¹. This resulted in a productivity of 0.27 g/(L·h). However, the reactor was not stable and fermentation deteriorated with time. Continuous fermentation of 35 g/L of starch solution resulted in a similar performance. These studies were performed in a vertical column reactor using Clostridium beijerinckii BA101 and P2 medium. It is anticipated that prolonged exposure of culture to acrylamide, which is formed during boiling/autoclaving of starch, affects the fermentation negatively.     

Development of continuous surfactin production from potato process effluent by Bacillus subtilis in an airlift reactor

The biosurfactant surfactin has the potential to aid in the recovery of subsurface organic contaminants (environmental remediation) or crude oils (oil recovery). However, high medium and purification costs limit its use in these high-volume applications. In previous work, we showed that surfactin can be produced from an inexpensive low-solids (LS) potato process effluent with minimal amendments or pretreatments. Previous research has also shown that 95% or more of the surfactin in Bacillus subtilis cultures can be recovered by foam fractionation. In this work, we present the results of research to integrate surfactin production with foam fractionation. Experiments were performed in an airlift reactor, with continuous collection of the foam through a tube at the top of the column. Preliminary results using both purified potato starch and unamended low-solids potato process effluent as substrates for surfactin production indicate that the process is oxygen limited and that recalcitrant indigenous bacteria in the potato process effluent may hamper continuous surfactin production.     

Economic analysis of ethanol production in California using traditional and innovative feedstock supplies

In this article, we estimate the costs of using alternative feedstocks to produce ethanol in a 40 million-gal facility in California’s San Joaquin Valley. Feedstocks include corn imported from Midwestern states and locally grown agricultural products such as corn, grapes, raisins, oranges, and other tree fruits. The estimated feedstock costs per gallon of ethanol include $0.92 for Midwestern corn, $1.21 for locally grown corn, $6.79 for grapes, $3.36 for raisins, $3.92 for citrus, and $1.42 for other tree fruit. Adjusting for coproduct values lowers the estimated net feedstock costs to $0.67/gal of ethanol for Midwestern corn, $0.96 for locally grown corn, $6.53 for grapes, and $3.30 for raisins. We also examine the potential increases in net revenue to raisin producers, made possible by having an alternative outlet available for selling surplus raisins.     

Alkali pre-treatment of Sorghum Moench for biogas production

This work studies the influence of the alkali pre-treatment of Sorghum Moench — a representative of energy crops used in biogas production. Solutions containing various concentrations of sodium hydroxide were used to achieve the highest degradation of lignocellulosic structures. The results obtained after chemical pre-treatment indicate that the use of NaOH leads to the removal of almost all lignin (over 99 % in the case of 5 mass % NaOH) from the biomass, which is a prerequisite for efficient anaerobic digestion. Several parameters, such as chemical oxygen demand, total organic carbon, total phenolic content, volatile fatty acids, and general nitrogen were determined in the hydrolysates thus obtained in order to define the most favourable conditions. The best results were obtained for the Sorghum treated with 5 mass % NaOH at 121°C for 30 min The hydrolysate thus achieved consisted of high total phenolic compounds concentration (ca. 4.7 g L^?1) and chemical oxygen demand value (ca. 45 g L^?1). Although single alkali hydrolysis causes total degradation of glucose, a combined chemical and enzymatic pre-treatment of Sorghum leads to the release of large amounts of this monosaccharide into the supernatant. This indicates that alkali pre-treatment does not lead to complete cellulose destruction. The high degradation of lignin structure in the first step of the pre-treatment rendered the remainder of the biomass available for enzymatic action. A comparison of the efficiency of biogas production from untreated Sorghum and Sorghum treated with the use of NaOH and enzymes shows that chemical hydrolysis improves the anaerobic digestion effectiveness and the combined pre-treatment could have great potential for methane generation.     

Continuous production of extracellular l-glutaminase by ca-alginate-immobilized marine Beauveria bassiana BTMF S-10 in packed-bed reactor

l-Glutamine amidohydrolase (l-glutaminase, EC 3.5.1.2) is a therapeutically and industrially important enzyme. Because it is a potent antileukemic agent and a flavor-enhancing agent used in the food industry, many researchers have focused their attention on l-glutaminase. In this article, we report the continuous production of extracellular l-glutaminase by the marine fungus Beauveria bassiana BTMF S-10 in a packed-bed reactor. Parameters influencing bead production and performance under batch mode were optimized in the order-support (Na-alginate) concentration, concentration of CaCl₂ for bead preparation, curing time of beads, spore inoculum concentration, activation time, initial pH of enzyme production medium, temperature of incubation, and retention time. Parameters optimized under batch mode for l-glutaminase production were incorporated into the continuous production studies. Beads with 12×10⁸ spores/g of beads were activated in a solution of 1% glutamine in seawater for 15 h, and the activated beads were packed into a packed-bed reactor. Enzyme production medium (pH 9.0) was pumped through the bed, and the effluent was collected from the top of the column. The effect of flow rate of the medium, substrate concentration, aeration, and bed height on continuous production of l-glutaminase was studied. Production was monitored for 5 h in each case, and the volumetric productivity was calculated. Under the optimized conditions for continuous production, the reactor gave a volumetric productivity of 4.048 U/(mL·h), which indicates that continuous production of the enzyme by Ca-alginate-immobilized spores is well suited for B. bassiana and results in a higher yield of enzyme within a shorter time. The results indicate the scope of utilizing immobilized B. bassiana for continuous commercial production of l-glutaminase.     

Hydrogen production from hydrogen sulfide using membrane reactor integrated with porous membrane having thermal and corrosion resistance

Using mathematical model and experimental method, the thermal decomposition of hydrogen sulfide in membrane reactor with porous membrane which has Knudsen diffusion characteristics was investigated. With mathematical model, the effect of characteristics of membrane reactor and operating conditions on H₂ concentration in the permeate chamber, y_H2, which increases at higher reaction temperature, lower pressure and higher ratio of cross-sectional area of the permeate chamber to that of the reactor, was evaluated. The reaction experiments with ZrO₂–SiO₂ porous membrane were carried out under the following conditions: temperature T, 923–1023 K; pressure in the reactor p^R_T, 0.11–0.25 MPa absolute; pressure in the permeate chamber p^P_T, 5 kPa absolute and inlet flow rate of H₂S f⁰_H2S, 3.2×10⁻⁵–1.5×10⁻⁴ mol/s. At p^R_T=0.11 MPa and f⁰_H2S=6.4×10⁻⁵, y_H2 increased from 0.02 at T=923 K to 0.15 at 1023 K. With the experimental condition, p^R_T=0.11, T=1023 K and f⁰_H2S=3.2×10⁻⁵, y_H2 was 0.22. The experimental results were compared with the results of the mathematical analysis. The agreement between both the results is found rather good at a lower reacting temperature, but not so good at a higher reacting temperature.     

Quantification of proteins in dairy products using an optical biosensor

Two recent techniques using optical immunosensor technology were developed for the quantification of milk proteins in dairy products. The first application is the simultaneous quantification of the 3 major caseins (alpha(s1), beta, and kappa). This assay consists of a 2-step sandwich strategy, with 2 monoclonal antibodies directed against the N- and C-terminal extremities of each of the caseins, respectively. This strategy permits only intact caseins to be quantified, and not their degradation products. The technique is fast (10 min), sensitive (detection limit about 0.87 microg/mL), and has been applied successfully to raw and drinking milks. In the second application, the severity of the heat treatment sustained by a milk of unknown origin is determined by quantifying separately the native and heat-denatured forms of alpha-lactalbumin with specific monoclonal antibodies. The technique allows discrimination of the different heat treatments studied (pasteurization, direct and indirect ultra-high temperature, sterilization), is fast (4 min), repeatable, fully automated, and requires no pretreatment of the milk sample.