Pretreatment Of Raw Material Research Articles

Influence of pre-treatment methods on quality indicators and mineral composition of plant milk from different sources of raw materials.

Pre-treatment of plant materials is essential in producing plant-based products and can affect their various organoleptic and physicochemical characteristics. This work aimed to study the effect of pre-treatment of vegetable raw materials, namely ultrasonic processing and freezing of raw materials under various low-temperature conditions, to obtain multiple types of vegetable milk and determine their characteristics. It is shown that by applying a certain kind of pre-treatment of vegetable raw materials it is possible to adjust organoleptic parameters and the content of solids, protein, fat, carbohydrates, fiber and mineral composition of various types of vegetable milk from soy, rice, oats, wheat, peas, buckwheat, pumpkin seeds and lentils. Ultrasound pre-treatment allows increasing of polyphenol content by an average of 15-20% for all types of plant milk, except for lentil milk. The results showed that ultrasound treatment for 3 min had the most significant effect on the overall acceptability for lentils, pumpkin, rice and pea milk. Pre-freezing at a temperature regime of -17 and -85 °C contributed to an increase in Fe, K, Zn, Ca, Mg, Si and P by an average of 30-100%, depending on the plant material. Pre-treatment of vegetable raw materials, including freezing and ultrasonic treatment, can positively affect the macro- and micronutrient composition of plant milk. However, the effect may vary depending on the type of raw material and processing conditions. © 2023 Society of Chemical Industry.

Preparation and characterization of high performance coal tar pitch-based carbon fiber

High performance carbon fiber based on coal tar pitch is a new type of functional material with unique properties, such as light weight, high strength, high modulus, high thermal conductivity, high electrical conductivity and low thermal expansion coefficient. It is a new type of functional material for both military and civilian use. In order to study the preparation of high performance carbon fiber based on coal tar pitch, this article obtained high performance carbon fiber based on coal tar pitch through raw material pretreatment, spinnable asphalt modulation, asphalt melt spinning, non-melting, carbonization, graphitization and other processes, and characterized the performance of spinnable mesocase asphalt and carbon fiber. The results show that high-performance spinnable mesophase pitch can be prepared by three steps raw material refining, hydrogenation modification and thermal polymerization. The mesophase content is 95%, the softening point is 280 °C, and the 3000 m filament can be spun under melt spinning conditions of 375 °C and 0.01 MPa. After graphitization, the coal pitch-based carbon fiber has excellent mechanical properties, small structural defects and a diameter of 12 μm. The tensile strength is 3089 MPa, the elastic modulus is 689 GPa, and the thermal conductivity is 902 w/(m·K).

Solid Oxide Electrolysis Cells Fabrication: From Single Cells to Batch Production

Energy transition towards a net-zero emission scenario requires, primarily, a significant increase on the renewable energy production capabilities. However, the inherent intermittency of most common renewable sources, added to the limitations of full electrification in some important hard-to-abate sectors (heavy-duty transport, aviation, steel industry...), implies also the need of developing reliable solutions for energy conversion and storage. Here, hydrogen is gaining more and more popularity in the recent years as an effective solution as energy carrier, mostly for the decarbonization of the key industries and transport. Among the different technologies under development for power-to-hydrogen conversion, solid oxide electrolysis (SOE) outstands due to its high conversion efficiency, fuel flexibility (e.g. CO2 electrolysis) and possibility of working in reversible mode (the same device both as electrolyser and fuel cell).Currently behind competing low temperature electrolysis technologies (AEL, PEMEL) in terms of technology readiness, main challenges of SOE today relate to long-term degradation, heat management and design and reliable fabrication of large stacks and systems. Although many projects are lately flourishing in this line, the number of players able to demonstrate an upscaled fabrication of SOE stacks and systems is still limited. The work presented here represents the first step carried out at CENER for the future demonstration of a pilot fabrication line of SOE stacks, from the optimization of functional materials and inks to the fabrication of single cells and building of 2-10 kW stacks.In this study, a fabrication route for SOE planar cells (5x5 cm2) is proposed, including the optimization of every single step of the process: raw material pre-treatment, ink/slurry development, functional printing and sintering. Particular emphasis is placed on ensuring a reliable upscaling for batch production of cells and thus materials are processed in large quantities (~1 L/batch). In terms of functional materials, standard electrode and electrolytes are chosen in a first approach, viz. Ni-YSZ as hydrogen electrode, YSZ as electrolyte and LSM-YSZ as air electrode. For film deposition, tape casting and screen printing techniques are combined. The electrochemical characterization of the fabricated cells will be presented and compared with commercial ones, including degradation analysis.

Study of Raw Material Pretreatment and the Microbiota Selection Effect on the Composting Process Efficiency

Lignocellulosic is a carbon source biomass composed of cellulose, hemicelluloses, and lignin, which are strongly associated with each other. This fact makes them hardly degradable by produced microbial enzymes when introduced to compost piles. To address this problem, a primary single or combined pretreatment method of this biomass allows for the separation of these complex, interlinked fractions, allowing a better accessibility for microbial enzymes. However, the rugged lignin component, in addition to several produced by products from these pretreatments, inhibit the microbial activity. For this, the optimization of these treatments with other interfering parameters is the base for a successful composting process. In this work, nine compost piles were initiated, in which their lignocellulosic fraction was subjected to chemical and microbiological treatments alone or combined while preserving a control. The obtained results showed that the combined pre-treatment of the primary organic raw materials with 10% NaOH and adapted microbial inoculum at 2.5% was the best suited for compost piles in Mediterranean regions. This treatment ensured the quickening of the composting process by 15 days, while yielding a final compost of a higher quality in regard to its physic-chemical characteristics, especially its C:N and CC values. Furthermore, it ensured a higher sanitation through the elimination of different microbial pathogens from the final compost, by means of the secondary metabolites produced by the microbial adapted consortia. This ‘tailor-made’ process could be replicated for the treatment of other generated sources of organic raw materials within the Mediterranean region.

Techno-economic and safety assessment of supercritical CO2 extraction of essential oils and extracts

Currently, products based on herbaceous plants are receiving global attention due to the significant rise in human awareness of environmental protection and well-being. These products contain compounds with valuable medicinal and nutritional effects. However, extracting these substances via conventional methods can be challenging concerning economic and environmental effects. Compared to conventional techniques, supercritical CO2 extraction is a clean technology that mitigates environmental issues and enhances extraction yields. This work focuses on developing a commercial-scale closed-cycle process using supercritical CO2 as a solvent with the possibility of varying feedstock material. The full process encompasses the raw material pre-treatment, the scCO2 extraction of compounds, and solvent recovery. This multiproduct processing unit includes three products: essential oil from garden angelica and extracts from roseroot and maral root. The process model was established using Aspen Plus®. Parallel to process design, safety was assessed by a hazard and operability study (HAZOP) to evaluate possible deviations during the operation. For assessing the feasibility of the process, a comprehensive techno-economic assessment was conducted. With this analysis, it can be seen that the designed production process is not only feasible but also economically profitable. For an annual production capacity of 13,240 kg, considering the three products, capital expenditure of 5.4 M€ was estimated. As to profitability, an internal rate of return of 40% and a payback time of 2.5 years resulted. In addition to economic benefits of the designed process, waste production was reduced by recycling used solvents and employing different approaches for mitigating greenhouse gas emissions.

Biogas Recovery from Anaerobic Co-Digestion of Poultry House Wastes for Clean Energy Production

Anaerobic digestion is a technology widely used for treatment of organic waste for biogas production as a source for clean energy. In this study, poultry house wastes (PHW) material was examined as a source for biogas production. The effects of inoculum addition, pretreatment of the substrate, and temperature on the biogas production were taken into full consideration. Results revealed that the effect of inoculum addition was more significant than the alkaline pretreatment of raw waste materials. The biogas recovery from inoculated waste materials exceeds its production from wastes without inoculation by approximately 70% at mesophilic conditions. Whereby, the increase of biogas recovery from pretreated wastes was by 20% higher than its production from untreated wastes at mesophilic conditions. The thermophilic conditions improved the biogas yield by approximately 73%. The kinetic of bio-digestion process was well described by modified Gompertz model and the experimental and predicted values of biogas production were fitted well with correlation coefficient values > 0.96 suggesting favorable conditions of the process.

Inorganic compounds of sunflower stems

This paper presents the results of studying the inorganic components of sunflower stems. The test objects are the extracts obtained at different pH values of the medium and ash samples before and after treatment of stems with water, acid, and alkali. The results show that the nature of the extractant has a negligible effect on the yield of extractive substances from the crushed stems. According to atomic absorption analysis, the main ions in extracts obtained in different media are potassium, calcium, magnesium, and sodium ions. The mass fraction of ash after treatment of stems with solutions at different pH values varies from 0.5 to 5.2%. The lowest ash yield is characterized by a sample of stems after acid extraction. According to energy dispersive X-ray fluorescence spectroscopy, all ash samples contain mainly K, Ca, Mg, and P compounds. The ash components of the core and outer part of the stem were also studied in comparison with the original sample. The ash content of the stem core (9.3%) is higher than that of the outer shell (7.4%). The IR spectroscopy shows that the nature of band splitting in the IR spectra of the ash samples practically does not depend on the stem part and the pretreatment of raw materials at different pH values. Absorption bands characteristic of carbonates and silicates are observed in the IR spectra of the stem ash. According to X-ray diffraction analysis, the studied ash samples are in a crystalline state.

Cavitation Reactor for Pretreatment of Liquid Agricultural Waste

One of the most well-known methods of intensifying the process of anaerobic digestion is the pretreatment of raw materials. For the first time, the use of a jet-driven Helmholtz oscillator for biomass pretreatment is proposed. The design of the device is optimal for creating hydraulic cavitation; however, in this case, acoustic oscillations are generated in the system and resonance occurs. In this study, the optimal design of this device was determined for the subsequent design of a cavitation reactor. The diameter of the resonant chamber was varied in the range from 28.3 to 47.5 mm, and its length from 6 to 14 mm; in addition, the diameter of the outlet was changed from 6.1 to 6.3 mm. Based on the experimental data obtained, it was found that the optimal ratio of the length of the resonator chamber to the diameter of the inlet nozzle is 1.73, and the inner diameter of the resonator chamber to the diameter of the inlet nozzle corresponds to 5.5. Improving the technology of agricultural waste disposal will ensure their maximum involvement in economic circulation, reduce the consumption of traditional fuel and energy resources, and improve the technological and machine-building base, which makes it possible to produce competitive cavitation reactors.

Catalytic pyrolysis of corn stalk for the production of aromatics: The effects of wet torrefaction and Zn/Ni-HZSM-5 on pyrolysis behavior

The pyrolysis of corn stalk (CS) was carried out to investigate the effect of wet torrefaction (WT) pre-treatment and Zn/Ni-HZSM-5 on the production of bio-oil characteristics. The synergy between WT and the loaded metal catalyst was also analyzed. The oxygen content of the CS was reduced from 50.5% to 40.8% with WT, and hemicellulose was almost removed. WT pretreatment also significantly reduced the oxygenated compounds of bio-oil and increased the selectivity of phenols, aromatics, and anhydro-sugars. The addition of catalyst improved the deoxygenation, oligomerization, and aromatization during pyrolysis. The loading of Zn and Ni could optimize the pyrolysis reaction path and increased the relative content of monocyclic aromatics (MAHs) from 3.58% to 9.67% and 6.44% during the pyrolysis of CS-WT, respectively, and bimetallic catalyst further enhanced the relative content of MAHs to 11.1%. The relative content of aromatics below C9 was higher than other groups (14.8%). Thus, the WT pretreatment of raw materials and synergistic effect of catalysts can jointly optimize the biomass pyrolysis reaction.

The influence of ultrasonic processing on the structure and electrophysical properties of fruit in combined drying

The intensification of ultrasonic vibrations for the processing of agricultural products is becoming increasingly important in the food industry, as it can reduce energy consumption for the dehydration of raw materials. The research aims to study the effect of sonication on the change of electrophysical parameters and structure of apple raw materials in the process of combined drying using direct electric heating. Using scanning electron microscopy, images of the surface structure of dried apple samples were obtained at different combinations of sonication duration and methods of heat supply to the raw material during the drying process. Based on the experimental studies, the dependences of the current flowing through the sample in the process of combined drying using direct electric heating on the duration of raw material processing in an ultrasonic bath were obtained. The influence of preliminary sonication on the maximum values of the current strength during direct electric heating was determined. The dependences of changes in the resistivity of apple samples during dehydration at different pretreatment durations were investigated. The effect of ultrasound on the initial resistivity of apples, the duration of electro-plasmolysis, and the resistivity values at which the maximum values of the direct electric heating current are observed were determined. The results of the experiments show that the pretreatment of raw materials in an ultrasonic bath can reduce the peak current values by up to 27%. The initial values of the resistivity of the raw material after sonication are reduced by 7.8-13.8% compared to the control samples. The obtained images of the dried fruit surfaces showed an increase in the porosity and roughness of the samples. The obtained results of experimental studies can become a prerequisite for the development of an energy-efficient technical means of ultrasonic processing of fruit and vegetable raw materials before drying and the selection of optimal operating modes

Конверсия пшеничных отрубей в целевые продукты биосинтеза

A more efficient bioconversion of renewable plant resources is a priority in modern biotechnology. An important aspect of the processing and pretreatment of cellulose raw materials is to obtain a high content of reducing substances in the final product. The present research objective was to determine the optimal conditions for the chemical transformation of plant polymers to obtain biologically valuable substances. The research results will reduce the final cost of biotechnological production.
 This research featured wheat bran polymers treated with sulfuric acid and relied on a set of standard research methods. The degree of polymer conversion was tested on native and mechanically activated wheat bran fractions of 600, 200, and 100 microns. The kinetics of the high-temperature chemical hydrolysis was as follows: temperature – 120–130°C, sulfuric acid concentration – 0.6–0.9%, treatment time – 30–60 min, hydromodule – 1:8;9;10. The quantitative and qualitative composition of mono- and disaccharides of hydrolysates was determined using the high performance liquid chromatography method. 
 The composition of wheat bran showed a low content of lignin (7.55%) and a high content of pentosans (17.9%). The highest content of reducing substances in hydrolysates was 640 mg/g bran. The optimal technological conditions with the highest content of reducing substances were as follows: hydromodulus – 1:10, temperature – 120°C, treatment time – 45 min, and sulfuric acid concentration – 0.9%. The greatest change in the content of mono- and disaccharides of hydrolysates belonged to pentoses: 78.2 mg/g of bran (in terms of xylose). The amount of easily hydrolysable carbohydrates and wheat bran fiber decreased by 80 and 19%, respectively.
 This research revealed the optimal parameters for the chemical hydrolysis of wheat bran to obtain biologically valuable carbohydrates. This area of research can be of practical use for producers of biofuels, chemicals, and food additives.

Evaluation of the mineral profile of wild plant raw materials and products of its processing for the creation of functional food products

Vegetable raw materials and their processed products are a source of necessary biologically active nutrients and are widely used in food production when creating functional and specialized nutrition products. Studies of the mineral profile of wild cranberry berries (Vaccinium oxycoccos) growing in the Republic of Karelia and berry processing products (juice and cake) with different methods of processing raw materials have been carried out. Studies of the mineral composition of fresh cranberry berries and their processed products obtained by various methods showed a high content of essential macro- and microelements in fresh berries, juices and cakes and allowed us to establish the regularity of migration and distribution of micronutrients depending on the method of pre-processing of raw materials. The data obtained during the experiment allow us to judge the high mineral profile of wild cranberry berries and its processed products and the content of certain elements (in particular phosphorus and manganese) in a physiologically significant amount, which explains the prospect of using products of processing wild berry raw materials to enrich food with micronutrients. Studies of the mineral composition of edible packaging films based on concentrated cranberry juice have shown a higher mineral profile of all samples of films with the addition of juice obtained with pretreatment of berry raw materials with steam, regardless of the type of structure-forming matrix, which is due to a higher content of concentrated juice solids. It has been established that the pre-processing of berry raw materials with steam before extracting the juice, as well as its subsequent concentration, allows processing raw materials with maximum preservation of essential components with a high degree of biological activity.)

ULTRASOUND-ASSISTED AND ENZYMATIC-BASED METHOD FOR ISOLATION OF β-GLUCANS FROM OAT BRAN

β-Glucans are a group of non-starchy polysaccharides, or (1,3),(1,4)-β-D-glucans, that can be found in the cell walls of several species of bacteria, algae, lichens, fungi, and cereal grains. These carbohydrates are extensively used in food industry, cosmetics, pharmaceuticals and healthcare, therefore optimization of the extraction and isolation of β-glucans from grain sources has an especial importance in various fields of biotechnology, drug design, food science and technology. The aim of the study was to develop an optimized technological scheme for isolation of β-glucans from oat bran based on ultrasonic and enzymatic processing of raw material. Materials and methods. β-Glucans were isolated from grinded oat cereals during multi-stage process, which includes extraction of grain fats, hydrobarothermic processing, ultrasonification, enzymatic hydrolysis of concomitant starch and proteins, precipitation of β-glucan fraction by ethanol, centrifugation, and dry-freezing. Yield of β-glucans from raw material and its concentration in the final product were determined after hydrolysis by sulfuric acid or enzymatic cleavage by endo-1,3(4)-β-glucanase. Results. As shown by acidic hydrolysis of the final product, the yield of β-glucans was 10.8 ± 0.23% and concentration was 79.6 ± 3.89%, while enzymatic hydrolysis gave 8.7 ± 0.82% and 65.1 ± 4.72%, respectively. Thus, the use of hydrobarothermic and ultrasound pre-treatment of raw material in combination with proteolytic digestion of ballast lipids and proteins allowed producing oat β-glucans in amounts comparable with those in case of acid- or alkali-based procedures. Conclusions. The described technological scheme of β-glucan isolation from oat bran based on sequential hydrobarothermic processing, ultrasonification, and enzymatic removing starch and proteins can be widely used for routine β-glucan production for various purposes in food technology, pharmacological industry, and medicine.

Influence of various parameters on the vegetable raw material pelleting process and pellets quality (review)

Determining the regularities of the process of pelleting vegetable raw materials is relevant for the improvement of technologies and technical equipment in order to reduce energy intensity and improve the quality of pellets. The generalization of the results of the research aimed at studying the influence of various parameters on the process of pelleting vegetable raw materials and the quality of feed and biofuel pellets is the purpose of the research. A selection and systematic review of the scientific literature on the subject of the study for the period of 2007-2022 has been carried out. The analysis has proved that heat pre-treatment and moistening of vegetable raw materials, as well as their composition and particle size are the factors that have the greatest impact on the quality of feed and biofuel pellets. Increasing the pressure in the range of 20...200 MPa results in increasing the pellets durability. A die temperature of around 100°C is optimum for obtaining dense pellets of highquality from vegetable raw materials. The design parameters of the pelletizer play an important role in obtaining high-quality pellets when processing vegetable raw materials. The design of the inlet in the form of a tapering cone helps to reduce energy consumption and pelleting pressure. An increase in the ratio of the die channel length to its diameter exponentially increases the pelleting pressure and its energy intensity. The interplay between the physical processes occurring in the pelletizer makes it difficult to interpret the impact of each parameter on the pelleting process, so different authors have different assessments of the contribution of individual factors in producing high-quality pellets. Therefore, the interaction between the individual pelleting parameters and their influence on the results of the process should be examined more precisely.

The key role of pretreatment for the one-step and multi-step conversions of European lignocellulosic materials into furan compounds.

Nowadays, an increased interest from the chemical industry towards the furanic compounds production, renewable molecules alternatives to fossil molecules, which can be transformed into a wide range of chemicals and biopolymers. These molecules are produced following hexose and pentose dehydration. In this context, lignocellulosic biomass, owing to its richness in carbohydrates, notably cellulose and hemicellulose, can be the starting material for monosaccharide supply to be converted into bio-based products. Nevertheless, processing biomass is essential to overcome the recalcitrance of biomass, cellulose crystallinity, and lignin crosslinked structure. The previous reports describe only the furanic compound production from monosaccharides, without considering the starting raw material from which they would be extracted, and without paying attention to raw material pretreatment for the furan production pathway, nor the mass balance of the whole process. Taking account of these shortcomings, this review focuses, firstly, on the conversion potential of different European abundant lignocellulosic matrices into 5-hydroxymethyl furfural and 2-furfural based on their chemical composition. The second line of discussion is focused on the many technological approaches reported so far for the conversion of feedstocks into furan intermediates for polymer technology but highlighting those adopting the minimum possible steps and with the lowest possible environmental impact. The focus of this review is to providing an updated discussion of the important issues relevant to bringing chemically furan derivatives into a market context within a green European context.

Microwave pretreatment of biomass for conversion of lignocellulosic materials into renewable biofuels

For the conversion of lignocellulosic material into renewable biofuels the microwave pretreatment of raw material is a new and promising technology. This work presents a numerical simulation of microwave heating of materials derived from sugar cane, african palm and green algae in microwave domestic oven. The power absorption of biomasses is studied in cylindrical and spherical shapes, with volumes varying from 10−5 m3 to 100 × 10−5 m3, as function of humidity (from 20% to 80%). Maxwell equations were employed to calculate the microwave electromagnetic field distribution in the microwave cavity and in the samples, coupled to heat equation when the humidity is varied. Penetration depth varied from 2 × 10−2 to 10 m and tanδ from 2 × 10−3 to 7 × 10−1 as function of humidity. Plots of electric field and temperature distribution inside the oven were done for sugar cane, palm oil and green algae for cylindrical and spherical samples for 30% and 65% of humidity in the samples. The coefficient of variation (COV) varied between 0.05 and 0.18. The rate of heating efficiency was evaluated using the degree of thermal runaway ΔT (5K<ΔT<75K) and evolution of average temperature T‾ (300K<T‾<370K) and their relationship with the energy absorbed by the samples and COV, respectively. The comprehensive evaluation coefficient, that describes the usability of a specific lignocellulosic material in industry, varied between 0.3 and 10.0, was calculated for the biomasses shapes and sizes as function of power and humidity.

The Influence of Subcritical Water Extraction Parameters on the Chemical Composition and Antioxidant Activity of Walnut (Juglans regia L.) Bark Extracts

This study investigated the impact of subcritical water extraction parameters on the polyphenols and flavonoids content in extracts made of the bark of walnut (Juglans regia L.), as well as antioxidant activity measured using the DPPH and FRAP methods. The total polyphenols (TPC) and flavonoid (TFC) were determined using the spectrophotometric (UV-Vis) method. The response surface methodology (RSM) was employed to optimize the yield of bioactive compounds. On the basis of developed model, the highest polyphenols (192.2 mg (GAE)/100 g (dry mass)) (GAE—gallic acid equivalent), flavonoids (88.3 mg(QE)/100 g (dry mass)) (QE—quercetin equivalent) contents and antioxidant activity (21.3 × 10−6 MTE/1 g (dry mass)) (TE-Trolox equivalent) were obtained under the following extraction conditions: temperature 131.6 °C, raw material fraction size 0.9 mm and process time 10 min. The greatest impact on the extraction yield was observed in the case of the temperature, whereas the raw material fraction size and the process time had a secondary impact. Obtained results indicate that a smaller particle size and a shorter time may improve the process; however, a reduction in particle size can be challenging for a pressure cell filtration system and consequently increase the cost of the raw material pretreatment process. With the reduction in the process time, a lower cost of extract production can be achieved. This study confirmed the importance of a proper selection of extraction parameters to obtain the demanded extract composition.

Isolation of essential oil from Mosla chinensis Maxim by surfactant-enzyme pretreatment in high-solid system and evaluation of its biological activity

Plant essential oil (EO) is an important natural active product, and the development of efficient and green EO separation technique has been one of the research hotspots. In this work, surfactant-enzyme pretreatment in high-solid system followed by microwave-assisted hydrodistillation (SEHS-MHD) was developed for the isolation of EO from Mosla chinensis Maxim. Through kinetic curve fitting, pretreatment of raw materials with combined enzyme (cellulase and hemicellulase of 1:1 in activity value) and surfactant (tween-20) in high-solid system (20% solid content) could provide a higher yield of EO. Compared with other reference methods, the yield of EO obtained by SEHS-MHD was significantly increased, which was mainly due to the synergistic interaction of enzyme and surfactant in the high-solid system. The results of gas chromatography-mass spectrometer analysis showed that the main components of M. chinensis EO were thymol and carvacrol, the contents of which were 75.38% and 17.20%, respectively. Additionally, the inhibitory enzyme activity and antifungal activity of M. chinensis EO were evaluated, the results of which indicated that EO had no obvious inhibitory activity on α-amylase and acetylcholinesterase, but had spectral antifungal activity. In general, the SEHS-MHD developed in this work is a potential and powerful alternative to traditional techniques for the sufficient isolation of EO from natural plant and crop materials. • Surfactant and enzyme were combined to pretreat raw materials in high-solid system. • Synergistic interaction of surfactant and enzyme in high-solid system was produced. • Kinetics and composition of essential oils under various conditions were studied. • Essential oil showed excellent inhibitory activity against plant pathogenic fungi.

Methods for Intensifying Biogas Production from Waste: A Scientometric Review of Cavitation and Electrolysis Treatments

This article presents future trends in research using microbiological methods to intensify bioprocesses for biogas production. The pretreatment by combinations of physical and chemical methods, such as cavitation and electrolysis, is considered. The approach of the article involved reviewing the residual area on the intensification technologies of anaerobic digestion with current methods to improve the quality and quantity of biogas. The most valuable reported positive results of the pretreatment of biological raw materials in the cavitation process were reviewed and are presented here. A model of the effect of electrolysis on the species diversity of bacteria in anaerobic digestion was developed, and changes in the dominance of the ecological and trophic systems were revealed on the basis of previous studies. The stimulating effect on biogas yield, reduction in the stabilization period of the reactor, and inactivation of microorganisms at lower temperatures is associated with different pretreatment methods that intensify anaerobic digestion. More research is recommended to focus on the electrolysis treatment of different types of waste and their ratios with optimization of regime parameters, as well as in combination with other pretreatments to produce biomethane and biohydrogen in larger quantities and in better qualities.

Reaction Behavior and Transformation Path of Zinc in the Heating-Up Zone during Sintering Process

Iron ore sintering is a simple and sustainable way to treat zinc-bearing secondary resources. In this paper, the reaction behavior of zinc was studied by combining thermodynamic calculation and simulation tests under sintering temperature and atmosphere. The evolution law of Zn-containing phases during the heating process was also revealed. The results showed that Zn-containing substances were mainly converted to ZnO when the temperature reached 700 °C in the pre-drying zone, and ZnO started to combine with Fe2O3 to form ZnFe2O4 when the temperature reached 800 °C in the combustion zone. ZnFe2O4 remained stable at 1300 °C, and did not change in the atmosphere with low CO concentration. In conventional sintering conditions, the removal rate of zinc was about 5 wt%, zinc was mainly converted to ZnFe2O4 and stuck in the sinter. Therefore, to meet the zinc amount of the blast furnace load, pretreatment of raw materials or ore matching to control zinc content is necessary.