Volumetric Productivity Research Articles

Simultaneous hydrogen and methane production by tequila vinasses dark fermentation in series with anaerobic digestion

Biofuels production from agro-industrial residues is a promising alternative for obtaining energy from renewable resources. Here, vinasses (tequila manufacture waste) were used as substrate to an anaerobic system comprised by a Continuous Stirred Tank Reactor (CSTR) with biomass carriers and an Upflow Anaerobic Sludge Blanket reactor (UASB) connected in series. The effect of the organic loading rate on the hydrogen and methane generation was evaluated through increase in fed vinasse concentration. Maximum volumetric production rates of 2.2 L H2/L-d in the CSTR and 0.12 L CH4/L-d in the UASB were obtained when feeding 20 g chemical oxygen demand per liter from vinasse diluted to 60 % of its original concentration. Feeding more concentrated vinasses provoked a decrease in the production of hydrogen and methane, coinciding with a 5 g/L-peak in reducing sugars in the CSTR, suggesting overload and acidification as reasons of the diminished performance. The highest hydrogen and methane equivalent energy obtained in the anaerobic system was estimated to be 2.6 kJ/L-d.

Nitrous oxide and methane production and consumption at five full-size denitrifying bioreactors treating subsurface drainage water

Nitrate (NO3−) removal in denitrifying bioreactors is influenced by flow, water chemistry, and design, but it is not known how these widely varying factors impact the production of nitrous oxide (N2O) or methane (CH4) across sites. Woodchip bioreactors link the hydrosphere and atmosphere in this respect, so five full-size bioreactors in Illinois, USA, were monitored for NO3−, N2O, and CH4 to better document where this water treatment technology resides along the pollution swapping to climate smart spectrum. Both surface fluxes and dissolved forms of N2O and CH4 were measured (n = 7–11 sampling campaigns per site) at bioreactors ranging from <1 to nearly 5 years old and treating subsurface drainage areas from between 6.9 and 29 ha. Across all sites, N2O surface and dissolved volumetric production rates averaged 1.0 ± 1.6 mg N2O-N/m3-d and 24 ± 62 mg dN2O-N/m3-d, respectively, and CH4 production rates averaged 6.0 ± 26 mg CH4-C/m3-d and 310 ± 520 mg dCH4-C/m3-d for surface and dissolved, respectively. However, N2O was consistently consumed at one bioreactor, and only three of the five sites produced notable CH4. Surface fluxes of CH4 were significantly reduced by the presence of a soil cover. Bioreactor denitrification was relatively efficient, with only 0.51 ± 3.5 % of removed nitrate emitted as N2O (n = 48). Modeled indirect N2O emissions factors were significantly lower when a bioreactor was present versus absent (EF5: 0.0055 versus 0.0062 kg N2O-N/kg NO3-N; p = 0.0011). While further greenhouse gas research on bioreactors is recommended, this should not be used as an excuse to slow adoption efforts. Bioreactors provide a practical option for voluntary water quality improvement in the heavily tile-drained US Midwest and elsewhere.

Evaluating end-to-end continuous antibody manufacture with column-free capture alternatives from economic, environmental, and robustness perspectives.

Process intensification efforts have renewed interest in the potential of end-to-end continuous manufacture with column-free capture alternatives. This article describes a decisional tool that encompasses mass balance and design equations, process economics, stochastic simulation and multi-criteria decision-making and enables the evaluation of different batch, and continuous flowsheets for monoclonal antibody (mAb) manufacture. The traditional batch process was compared with end-to-end continuous bioprocesses with either protein A capture or column-free capture employing aqueous two-phase extraction or precipitation from economic, environmental, and robustness perspectives. The cost of goods analysis predicted that continuous flowsheets could offer substantial cost savings (~20%-40%) over the batch process at low and medium annual commercial demands (100-500 kg); however, at tonnage demands they resulted in either comparable or higher costs. Comparing the continuous options, the continuous flowsheets with protein A or precipitation yielded similar COG/g values, while aqueous two-phase extraction presented higher costs. The analysis of overall process mass intensities accounting for water and consumables suggested that the continuous flowsheet with protein A would result in the lowest environmental burden. When the economic, environmental, and operational criteria were reconciled using multi-criteria decision-making analysis, the continuous protein A-based flowsheet was found to be the most favorable. A target analysis highlighted the need for process improvements in the following parameters to reduce the manufacturing costs of the continuous column-free capture options below that of protein A: the perfusion volumetric productivity, the harvested cell culture fluid percentage in column-free operations, the column-free step yields along with the implementation of buffer concentrates.

Experimental Insights into the Fermentation of Pyro-Syngas to Ethanol in a Semi-Batch and Continuous Stirred Bioreactor with Mathematical Modelling and Optimization

Syngas fermentation can play an important role in implementing the concept of biorefinery as it can serve as a platform to convert high-lignin biomass to biofuels. For the utilization of this process in commercial scale, the generation of an experimental database supported by a deterministic mathematical model and optimization is necessary. In this study, a locally isolated clostridial consortium, UACJUChE1, was used to convert pyro-syngas to ethanol and acetic acid. Mathematical models were developed and validated for a 3 L stirred and gas-sparged bioreactor operated in both semi-batch and continuous modes. The volumetric productivity of ethanol was correlated with the dilution rate and the gas residence time. The performance of the bioreactor, run in both semi-batch and continuous modes, was optimized using response surface methodology. For the semi-batch operation, a maximum ethanol concentration of 13.122 g/L after 30 h operation was achieved at optimum values of pyrolysis temperature, ratio of gas to liquid volume (VG/VL), and volumetric gas flow rate of 648 °C, 0.46, and 6.7 L/h respectively. For continuous operation, a maximum ethanol concentration of 29.450 g/L after 300 h is obtained at optimum values of VG/VL and ratio of gas to liquid volumetric flow rate of 0.28 and 335.148, respectively.

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507.

Xylitol is a pentose-polyol widely applied in the food and pharmaceutical industry. It can be produced from lignocellulosic biomass, valorizing second-generation feedstocks. Biotechnological production of xylitol requires scalable solutions suitable for industrial scale processes. Immobilized-cells systems offer numerous advantages. Although fungal pellet carriers have gained attention, their application in xylitol production remains unexplored. In this study, the yeast strain P. fermentans WC 1507 was employed for xylitol production. The optimal conditions were observed with free-cell cultures at pH above 3.5, low oxygenation, and medium containing (NH4)2SO4 and yeast extract as nitrogen sources (xylitol titer 79.4g/L, YP/S 66.3%, and volumetric productivity 1.3g/L/h). Yeast cells were immobilized using inactive Aspergillus oryzae pellet mycelial carrier (MC) and alginate beads (AB) and were tested in flasks over three consecutive production runs. Additionally, the effect of a 0.2% w/v alginate layer, coating the outer surface of the carriers (cMC and cAB, respectively), was examined. While YP/S values observed with both immobilized and free cells were similar, the immobilized cells exhibited lower final xylitol titer and volumetric productivity, likely due to mass transfer limitations. AB and cAB outperformed MC and cMC. The uncoated AB carriers were tested in a laboratory-scale airlift bioreactor, which demonstrated a progressive increase in xylitol production in a repeated batch process: in the third run, a xylitol titer of 63.0g/L, YP/S of 61.5%, and volumetric productivity of 0.52g/L/h were achieved. This study confirmed P. fermentans WC 1507 as a promising strain for xylitol production in both free- and entrapped-cells systems. Considering the performance of the wild strain, a metabolic engineering intervention aiming at further improving the efficiency of xylitol production could be justified. MC and AB proved to be viable supports for cell immobilization, but additional process development is necessary to identify the optimal bioreactor configuration and fermentation conditions.

Optimal conditions for 2‐phenylethanol production from l‐phenylalanine by Acinetobacter soli ANG344B

AbstractBACKGROUND2‐Phenylethanol (2‐PE) is a valuable flavor compound renowned for its rose‐like scent and widespread application in the cosmetic, perfume and food industries. While it can be naturally sourced from plants, the majority is currently produced through chemical synthesis, leading to environmental concerns. As an ecofriendly alternative, biotechnological production of 2‐PE presents a promising solution, yielding a natural product.RESULTSIn this work, the newly isolated bacterium Acinetobacter soli ANG344B was used to produce 2‐PE from l‐phenylalanine (L‐Phe), using glucose as carbon source, aiming to determine the best conditions for cellular growth and aroma production. The optimal conditions for Acinetobacter cultivation and 2‐PE production were 30 °C and pH 7. Further, yeast extract proved to be a key element for 2‐PE production. The concentration of L‐Phe that maximizes 2‐PE volumetric productivity was found to be 5 g L−1, present in the cultivation media from the beginning of the cultivation. Under these conditions 2.14 ± 0.18 g L−1 of the aroma compound was produced, which is the highest concentration obtained for a wild‐type bacterium. The toxicity of 2‐PE was also evaluated, revealing that cellular growth of A. soli ANG344B was adversely affected at concentrations above 1 g L−1, and beyond 4 g L−1 no cellular growth was observed.CONCLUSIONBy elucidating the crucial factors affecting 2‐PE production by A. soli ANG344B, we pave the way for the development of biotechnological strategies to harness its potential as a natural and sustainable aroma compound. © 2024 Society of Chemical Industry (SCI).

Biotransformation of 2-keto-4-hydroxybutyrate via aldol condensation using an efficient and thermostable carboligase from Deinococcus radiodurans

The bioconversion of 4-hydroxy-2-keto acid derivatives via aldol condensation of formaldehyde and pyruvate has received substantial attention as potential source of chemicals for production of amino acids, hydroxy carboxylic acids, and chiral aldehydes. We developed an environmentally friendly biocatalyst consisting of a novel thermostable class II pyruvate aldolase from Deinococcus radiodurans with maltose-binding protein (MBP-DrADL), which has specific activity of 46.3 µmol min–1 mg–1. Surprisingly, MBP-DrADL maintained over 60% of enzyme activity for 4 days at 50 to 65 °C, we used MBP-DrADL as the best candidate enzyme to produce 2-keto-4-hydroxybutyrate (2-KHB) from formaldehyde and pyruvate via aldol condensation. The optimum reaction conditions for 2-KHB production were 50 °C, pH 8.0, 5 mM Mg2+, 100 mM formaldehyde, and 200 mM pyruvate. Under these optimized conditions, MBP-DrADL produced 76.5 mM (8.94 g L–1) 2-KHB over 60 min with a volumetric productivity of 8.94 g L–1 h–1 and a specific productivity of 357.6 mg mg-enzyme–1 h–1. Furthermore, 2-KHB production was improved by continuous addition of substrates, which produced approximately 124.8 mM (14.6 g L–1) of 2-KHB over 60 min with a volumetric productivity and specific productivity of 14.6 g L–1 h–1 and 583.4 mg mg-enzyme–1 h–1, respectively. MBP-DrADL showed the highest specific productivity for 2-KHB production yet reported. Our study provides a highly efficient biocatalyst for the synthesis of 2-KHB and lays the foundation for large-scale production and application of high-value compounds from formaldehyde.Graphical

Assessing the application of marine microalgae Dunaliella salina in a biorefinery context: production of value‐added biobased products

AbstractMicroalgae are a rich source of bioactive compounds such as pigments, carbohydrates, lipids, proteins, and other substances of interest. Thus, given the possible variety of products that can be obtained from them, it is important to determine their biochemical composition, taking into consideration the species and cultivation conditions, so that they can be used as feedstock in biorefineries, with the aim of using all the biomass in the biorefining processes and increasing its economic viability. This work aimed to characterize the biochemical composition of the microalgae Dunalliela salina in a multi‐product biorefinery context, focusing on the production of high value‐added compounds such as pigments and biofuels. The biomass concentration obtained was 1.15 g·L−1 and the volumetric productivity was 164.28 mg·L−1·day−1, providing fractions of 23.86 ± 0.24% of lipids, 10.80 ± 0.86% of carbohydrates, and 5.71 ± 0.50% of proteins. The microalgal biomass contained pigment concentrations of 0.896 and 0.5380 mg·g−1of chlorophylls a and b, and 0.2043 mg·g−1 of total carotenoids. Thus, the data suggest that D. salina has biotechnological potential for application in integrated multi‐product biorefineries, focused on obtaining energy and high added value products simultaneously.

One‐pot Heterogeneous Biocatalysis under Thermal Decay for Fructose Production from Lactose using Co‐Immobilized Enzymes: Modeling and Simulation

AbstractMulti‐enzyme reaction systems have become an interesting option to avoid transformation and purification steps in productive reactor‐based systems; when carried out in a single vessel, they are termed one‐pot systems. This novel work aims to model and simulate the behavior of a one‐pot heterogeneous catalysis system in a batch‐stirred bioreactor and in a continuous stirred bioreactor with co‐immobilized enzymes to determine the compromise operation temperature that maximizes the volumetric productivity, considering thermal decay of the biocatalyst. The production of fructose from lactose is considered a case study, using co‐immobilized ‐galactosidase ( ‐gal) and glucose‐isomerase (GI) in a spherical particle. A diffusion and reaction mathematical model was used to calculate the effectiveness factor for every reaction species considering the thermal decay of both enzymes. Simulations in both batch and continuous operation were done at temperatures ranging from 40 to 60 °C, for initial enzyme activity load ratios ranging from 0.1 to 0.9 IUGI IU . Resulting effectiveness factors were close to one, indicating no significant limitations on reaction rates due to internal diffusional constraints. In both cases, temperature exerted a more substantial effect than the initial enzyme activity load ratio, showing different scenarios of high volumetric productivity (batch) or amount of produced fructose (continuous).

First- and second-generation integrated process for bioethanol production: Fermentation of molasses diluted with hemicellulose hydrolysate by recombinant Saccharomyces cerevisiae.

The integration of first- (1G) and second-generation (2G) ethanol production by adding sugarcane juice or molasses to lignocellulosic hydrolysates offers the possibility to overcome the problem of inhibitors (acetic acid, furfural, hydroxymethylfurfural and phenolic compounds), and add nutrients (such as salts, sugars and nitrogen sources) to the fermentation medium, allowing the production of higher ethanol titers. In this work, an 1G2G production process was developed with hemicellulosic hydrolysate (HH) from a diluted sulfuric acid pretreatment of sugarcane bagasse and sugarcane molasses. The industrial Saccharomyces cerevisiae CAT-1 was genetically modified for xylose consumption and used for co-fermentation of sucrose, fructose, glucose, and xylose. The fed-batch fermentation with high cell density that mimics an industrial fermentation was performed at bench scale fermenter, achieved high volumetric ethanol productivity of 1.59 g L-1 h-1, 0.39 g g-1 of ethanol yield, and 44.5 g L-1 ethanol titer, and shown that the yeast was able to consume all the sugars present in must simultaneously. With the results, it was possible to establish a mass balance for the global process: from pretreatment to the co-fermentation of molasses and HH, and it was possible to establish an effective integrated process (1G2G) with sugarcane molasses and HH co-fermentation employing a recombinant yeast.

Characterization of Lactic Acid Bacteria Isolated From Rotting Oranges and Use of Agropastoral Processing By-products as Carbon and Nitrogen Sources Alternative for Lactic Acid Production.

This study investigated the ability of lactic acid bacteria (LAB) isolated from oranges to use fish by-products (FB) and chicken by-products (CB) as nitrogen sources alternative to yeast extract for lactic acid (LA) production in a papaya by-product medium as a carbon source. Once the fermentation agents had been isolated, they were subjected to biochemical and molecular characterization. Inexpensive nitrogen sources, precisely CB and FB, were prepared, freeze-dried, and yield evaluated. Also, before to the fermentation experiments, the Total Kjehdahl Nitrogen (TKN) of these by-products and that of the yeast extract were determined. Then, three production media differing in terms of nitrogen source were formulated from these nitrogen sources. From the 22 LAB isolated from orange, two isolates of interest (NGO25 and NGO23) were obtained; all belonging to the Lactiplantibacillus plantarum species based on 16S rRNA gene sequencing. Furthermore, the production yield powder obtained after lyophilization of 1 L of CB and FB surpernatant were, respectively, 16.6 g and 12.933 g. The TKN of different nitrogen sources powder were 71.4 ± 0.000% DM (FB), 86.145 ± 0.001% DM (CB), and 87.5 ± 0.99% DM (yeast extract). The best kinetic parameters of LA production (LA (g/L): 31.945 ± 0.078; volumetric productivity (g/L.h): 1.331 ± 0.003; LA yield (mg/g) 63.89 ± 0.156; biomass (g/L) 7.925 ± 0.035; cell growth rate (g/L.h): 0.330 ± 0.001) were recorded by Lactiplantibacillus plantarum NGO25 after 24 h of fermentation. The latter data were obtained in the production medium containing CB as nitrogen sources. In addition, this production medium cost only $0.152 to formulate, compared to yeast extract which required $1.692 to formulate. Thus, freeze-dried CB can be used as an alternative to yeast extract in large-scale production of LA.

Impact of cathodic pH and bioaugmentation on acetate and CH4 production in a microbial electrosynthesis cell.

This study compares carbon dioxide conversion in carbonate-fed microbial electrosynthesis (MES) cells operated at low (5.3), neutral (7) and high (8) pH levels and inoculated either with wild-type or bioaugmented mixed microbial populations. Two 100 mL (cathode volume) MES cells inoculated with anaerobic digester sludge were operated with a continuous supply of carbonate solution (5 g L-1 as CO3 2-). Acetate production was highest at low pH, however CH4 production still persisted, possibly due to pH gradients within the cathodic biofilm, resulting in acetate and CH4 volumetric (per cathode compartment volume) production rates of 1.0 ± 0.1 g (Lc d)-1 and 0.84 ± 0.05 L (Lc d)-1, respectively. To enhance production of carboxylic acids, four strains of acetogenic bacteria (Clostridium carboxidivorans, Clostridium ljungdahlii, Clostridium autoethanogenum, and Eubacterium limosum) were added to both MES cells. In the bioaugmented MES cells, acetate production increased to 2.0 g (Lc d)-1. However, production of other carboxylic acids such as butyrate and caproate was insignificant. Furthermore, 16S rRNA gene sequencing of cathodic biofilm and suspended biomass suggested a low density of introduced acetogenic bacteria implying that selective pressure rather than bioaugmentation led to improved acetate production.

Real-world assessment of a decentralized food waste anaerobic digestion system: A test-bedding case study application

Addressing the global challenge of food waste, this research delves into the assessment of an on-site food waste treatment solution through a full-scale decentralized anaerobic digester (AD) system, specifically deployed at a Singapore hawker centre. Demonstrating efficiency in Singapore's tropical climate (29 °C) without external heating, the 10.8 m³ digester exhibited resilience over 234 days, navigating through real-world fluctuations in average organic loading rates ranging from 0.07 ± 0.02 to 0.81 ± 0.38 kgVS/(m3d). The normalized specific biogas production averaged 0.70 ± 0.48 m3/kgVS, accompanied by a methane concentration of 56.9 ± 2.9%. During peak performance, with an organic loading rate of 1.1 kgVS/(m3d), the system achieved an impressive volumetric biogas production rate of 1.18 m3biogas/m3reactor, equivalent to 1.1 m3/kgVS of specific biogas production per day. The energy assessment revealed consumption rates of 0.57–0.97 m3/kWh, positioning it comparably with commercialized biogas technologies in China and Taiwan. In the realm of microbiome composition, the prevalence of hydrogenotrophic methanogens, including Methanomicrobia, Thermoplasmata, and Nanoarchaeia, is notable. These methanogens showcase a remarkable tolerance to acetate, surpassing common aceticlastic methanogens by 11 times, thereby playing a pivotal role in enhancing the stability of the AD system over extended periods. On the economic front, the present AD system yielded losses ranging from SG$552,434 to SG$742,919, primarily due to a low payback period and substantial investment costs. Profitability becomes a possibility if there are significant reductions in capital costs and operator salaries. The challenges encountered during the operation of this decentralized system, along with the corresponding mitigation measures, are thoroughly discussed. Positioned as a promising test-bedding model, this application underscores its technical feasibility potential for sustainable food waste management through AD technology in Singapore. It stands as a replicable prototype, contributing to closing the food waste loop and advancing the bioeconomy.

Lactic acid production by Lactobacillus casei using a sequence of seasonally available fruit wastes as sustainable carbon sources.

Introduction: Lactic acid (LA) production from fossil resources is unsustainable owing to their depletion and environmental concerns. Thus, this study aimed to optimize the production of LA by Lactobacillus casei in a cultured medium containing fruit wastes (FWs) from agro-industries and second cheese whey (SCW) from dairy production, supplemented with maize steep liquor (MSL, 10% v/v) as the nitrogen source. Methods: The FWs were selected based on seasonal availability [early summer (early ripening peach), full summer (melon), late summer (pear), and early autumn (apple)] and SCW as annual waste. Small-scale preliminary tests as well as controlled fermenter experiments were performed to demonstrate the potential of using various food wastes as substrates for LA fermentation, except for apple pomace. Results and discussion: A 5-cycle repeated batch fermentation was conducted to optimize waste utilization and production, resulting in a total of 180.56g/L of LA with a volumetric productivity of 0.88g/L∙h. Subsequently, mechanical filtration and enzymatic hydrolysis were attempted. The total amount of LA produced in the 5-cycle repeated batch process was 397.1g/L over 288h, achieving a volumetric productivity of 1.32g/L∙h. These findings suggest a promising biorefinery process for low-cost LA production from agri-food wastes.

Lake-wide measurements of primary productivity in Lake Erie

Abstract Few lake-wide, seasonal primary production measurements have been made in Lake Erie. None more recent than 1997 have been reported in the literature. In 2019 we used 13C uptake to measure production at 11 stations across the lake during three surveys in May, July, and September and at four of these stations during two additional surveys in April and August. Samples were collected at two depths (2 m and 6 m) and incubated on deck using eight levels of irradiance. We fit the resultant photosynthesis-irradiance curves with models that included the initial slope at low light levels, the maximum photosynthesis rate at light saturation, and when warranted, the negative slope at high irradiance. During May, there was little variation in chlorophyll-normalized volumetric productivity with sample depth, and productivity generally was higher nearshore and in the western basin than it was offshore. The distinction between nearshore and offshore stations was less pronounced in July, but nearshore productivity was higher than offshore in September. Using the photosynthesis data from all five surveys, chlorophyll concentration profiles, and estimated clear-sky solar insolation, we calculated time series of vertically integrated daily production at a western basin station, two central basin stations, and an eastern basin station. Central basin production was highest during August, estimated to be 748 mg C m-2 d-1 and 779 mg C m-2 d-1 at our two stations. Production peaked in July in the western basin (510 mg C m-2 d-1) and September in the eastern basin (421 mg C m-2 d-1). Whole-lake seasonal areal phytoplankton photosynthesis was estimated as 1.661E6 tonnes, about half of estimates made in the 1990s using 14C methods. These results inform our understanding of spatial-temporal trends in Lake Erie productivity and highlight the need for continued measurements of Lake Erie primary production.

Cell-Free Systems for the Production of Glycoproteins.

Cell-free protein synthesis (CFPS), whereby cell lysates are used to produce proteins from a genetic template, has matured as an attractive alternative to standard biomanufacturing modalities due to its high volumetric productivity contained within a distributable platform. Initially, cell-free lysates produced from Escherichia coli, which are both simple to produce and cost-effective for the production of a wide variety of proteins, were unable to produce glycosylated proteins as E. coli lacks native glycosylation machinery. With many important therapeutic proteins possessing asparagine-linked glycans that are critical for structure and function, this gap in CFPS production capabilities was addressed with the development of cell-free expression of glycoproteins (glycoCFE), which uses the supplementation of extracted lipid-linked oligosaccharides and purified oligosaccharyltransferases to enable glycoprotein production in the CFPS reaction environment. In this chapter, we highlight the basic methods for the preparation of reagents for glycoCFE and the protocol for expression and glycosylation of a model protein using a more productive, yet simplified, glycoCFE setup. Beyond this initial protocol, we also highlight how this protocol can be extended to a wide range of alternative glycan structures, oligosaccharyltransferases, and acceptor proteins as well as to a one-pot cell-free glycoprotein synthesis reaction.

Utilizing an integrated AHP-COPRAS approach for battery selection in electric vehicles

Internal combustion engine vehicles provide better performance and longer-range using fossil fuels such as gasoline and diesel. However, fossil fuels are non-renewable and cause environmental pollution, alternative fuels such as blends of ethanol and biodiesel, hydrogen etc have been sought for these vehicles. On the other hand, some researchers prefer to design alternative vehicles such as hybrid and electrical vehicles, instead of changing the fuel type. Among the studied topics for alternative vehicles, the battery is one of the most important components, especially in electrical vehicles. Batteries are diversified with different criteria such as battery life, nominal voltage, energy density, volumetric energy density, specific power, operating temperature, and production cost. In this study, the expert perspective was utilized when selecting the battery type to be employed for the energy source through utilizing the Integrated Analytical Hierarchy Process (AHP) - Complex Proportional Assessment (COPRAS), a multi-criteria decision-making approach. Various batteries such as Lead-acid (Pb-acid), Nickel-cadmium (Ni-Cd), Ni-MH, Sodium Nickel Chloride (Zero Emission Battery Research Activity-ZEBRA), Lithium –Ion (Li-Ion) Battery were evaluated in terms of different criterion. Among the alternatives the Li-ion battery type is chosen as the best option and the Ni-Cd battery is the least chosen alternative.

In English

The article discusses methods for obtaining carbon nanostructures (CNS), as well as their use to create three-dimensional (3D) products using FDM, CJP, SLA, SLS technologies. The process of manufacturing consumables for 3D printing technologies (FDM, CJP, SLA, SLS) for creating new composite 3D products based on carbon nanostructures is described. The paper contains a detailed description of which methods of CNS synthesis are more productive and how they allow you to guarantee the production of one or another type of CNS. The paper analyzes the existing 3D printing technologies using CNS, developed a scheme for the full cycle of creating a 3D product containing CNS, taking into account various methods for the synthesis of CNS with the transformation of graphite or other carbon-containing material. It also describes the process of creating composite coils for FDM 3D printing from nanocomposite filaments (rigid polymer-CNS) based on a rigid polymer, which have undergone the process of preparation in a special mixer. The process of preparing consumables and printing a 3D volumetric product using FDM, CJP, SLA, SLS technologies using CNS is described. An overview of consumables for 3D products of FDM technology is presented. The analysis of composite 3D products (ceramic-CNS, rigid polymer-CNS) obtained by FDM and CJP technology was carried out. The paper also describes the three most productive methods for the synthesis of CNS: plasma-chemical synthesis in gas or liquid and pyrolytic method. These synthesis methods make it possible to guarantee the production of a certain type of CNS and have a high quality of the obtained nanoproducts. Various types of CNS are described, including soluble (fullerenes and fullerene-like structures) and insoluble nanostructures (graphenes, carbon nanotubes, carbon nanofibers, nanocomposites, etc.).

Wood density estimation using dendrometric and edaphoclimatic data in artificial neural networks

Forestry measurement is aimed at volumetric production of wood; however, for the pulp processing industry, the main interest is productivity in wood biomass and, to know this variable, it is necessary to determine the basic wood density (BWD) beforehand. Artificial neural networks (ANN) have been used in the forestry sector quite successfully to describe the dynamics of forest characteristics, such as estimating wood volume. In this context, the objective of this study was to assess the accuracy of the basic wood density estimates by means of ANN’s with Continuous Forest Inventory (CFI) and edaphoclimatic input variables. The database consisted of 3,797 data, from permanent plots of the CFI conducted in Eucalyptus sp stands and edaphoclimatic data from the planting sites. The five best ANNs were selected and the analysis of the estimates was carried out through the correlation between the estimated and BWD, the relative root mean square error (RMSE%) and graphical information. It was observed that both the CFI, edaphoclimatic information and the combination of both are potential and present similar results for the basic wood density estimate, and the errors associated with the estimates are between 3.9% to 3.5%. The ANNs based only on the CFI information presented higher RMSE. The use of ANN’s is feasible for estimating BWD and allows for excellent accuracy statistics.

Experimental study of volumetric sand production with gas flow

The presence of sand in a production stream has been a common issue for wells drilled in high permeability sandstone formations. In the case of gas producing reservoirs, sand production can be particularly hazardous due to the high gas velocities. It can among others lead to erosion of downhole components and surface equipment and to significant production downtime. A comprehensive experimental study was conducted to investigate the effects of gas flow on sand production. This was accomplished by comparing gas flow tests to tests with oil or water flow. In these tests, hollow cylinder sandstone specimens, initially wet or at ambient humidity conditions, were isotropically compressed under simultaneous fluid injection. One-phase as well as two-phase flow experiments were carried out to simulate important processes encountered in gas fields, like water capillary flow or water-cut. The results showed that sand onset was delayed in the gas flow experiments, which agrees with experimental observations in the literature. The delayed sand onset, i.e., higher sand onset stress, was related to water evaporation due to gas flow, termed flow-through drying, which strengthens the rock. The water-sensitive strength of sandstones was also examined by completing a series of uniaxial compression tests at various water saturations. The analysis of the volumetric sand production data and the X-ray CT-scans of the tested specimens showed that the decreased capillary bonds between grains when only one fluid is present in the pores, e.g., one-phase water or gas flow, results in continuous sand production of individual grains or small-sized flakes, creating large voids in the vicinity of the hole. Under such conditions, the constantly enlarging failure zone eventually causes the total collapse of the specimen. In contrast, specimens with higher capillary cohesion due to a water-oil or water-gas interphase show post sand onset stability and lower sand rate where, due to higher grain to grain cohesion, chunks of failed rock material remain in the hole and provide additional support that prevents the rapid collapse of the specimen even as the applied stress increases.