DOAJ (DOAJ: Directory of Open Access Journals), Jul 1, 2009
Today, rotary dryers are often use to dry sawdust prior to their further processing, palletizing ... more Today, rotary dryers are often use to dry sawdust prior to their further processing, palletizing and briquetting, into commercially voluble product. This paper present mathematical model for drying process of sawdust particles in a triple pass rotary dryer. As basis for this model, we used existing mathematical models for drying of sawdust and other biological materials in a single pass rotary dryer, which are modified and extended in order to satisfy mathematical description of motion of material in the triple pass rotary dryer. Developed mathematical model is used as basis for further developing of the simulation model that predict temperature and moisture profile sawdust and drying along the dryer. In order to solve and validate developed rotary dryer model, commercial triple pass rotary dryer, installed in enterprise Panensa near town of Srbac, have been analysed, and measured sawdust drying data have been used for comparison. Comparison between predicted and the measured results were good. Mathematical model i.e. rotary dryer simulation model developed in this paper is going to enable better management and controlling of process in the mentioned commercial rotary dryer as well as in other rotary dryers for wood waste with modification of appropriate model parameters
There is an urgent need for replacement of fossil fuels worldwide. Raw biomass has a low energy d... more There is an urgent need for replacement of fossil fuels worldwide. Raw biomass has a low energy density, contains too much moisture, can rot, and it is hygroscopic. This paper presents a very prominent thermal technology that could overcome mentioned deficiencies of raw biomass. This technology is known as torrefaction. Torrefaction is mainly used to convert lignocellulosic materials into 'fuels' that can be used in power plants, combustion units, or gasifiers.
The negative impact of climate change, especially in urban areas, requires the use of new constru... more The negative impact of climate change, especially in urban areas, requires the use of new construction technologies and materials, harmonized with environmental aspects. One such approach is the construction of green areas on flat roofs of buildings. The positive impact of greening roofs is reflected in several important aspects: environmental, economic, and social. The pilot area that was researched is characterized by a high coefficient of construction. All this affects the creation of the so‐called heat island and bad microclimatic conditions, as well as the lack of areas that can be arranged for the rest of the local population. In addition to the impact of this type of urban planning on the preservation of the city's environment, the costs of building green roofs are also presented. In the final part of the article, the life cycle impact assessment (LCIA) of green roof layers is presented, using the Eco‐indicator method to show the environmental impact of a materials based ...
The estimation of growth or inactivation of bacterial population in fruits during preservation an... more The estimation of growth or inactivation of bacterial population in fruits during preservation and storage provides useful information for the improvement of the safety of fresh-cut fruits and vegetables. This paper addressed the attachment to the surface and the growth in the flesh of apple fruits of four bacterial cultures (Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa). The growth of the bacterial cultures in apple flesh was monitored at particular time intervals, and Gompertz parameters, i.e. maximum number of bacteria (Pm), the maximum growth rate of bacteria rp,m, and lag time tl, were used to determine the growth kinetics. After the immersion, the highest number of P. aeruginosa and the lowest number of B. cereus adhered to the apples. After washing and swabbing, E. coli was reduced from the surface of apples to the highest extent (by 3.34 log cfu g-1), while the number of B. cereus was reduced to the lowest extent (1.66 log cfu g-1). Fitted curves of the Gompertz model corresponded quite well to the measured values of the number of microorganisms with R2 = 0.92-0.98. The values of the standard error (0.17-0.37) and extremely low p values of the Fischer test (p < 0.0001) indicated strict dependence between the model predicted and the maximum population density. The predicted values of the maximum number of microorganisms (Pm) correspond almost exactly to the actual values. A similar conclusion can be drawn for the maximum growth rate of microorganisms (rp,m), with the measured value being slightly higher than predicted values.
Introduction. This article presents the development of mathematical models related to the effect ... more Introduction. This article presents the development of mathematical models related to the effect of the initial content of dry matter, yeast, and yeast energizer on the fermentation rate, the alcohol content, and the dry matter content in the finished product – mead. Study objects and methods. The mathematical models were developed by using the response surface methodology (RSM). The effect of yeast, dry matter, and yeast energizer contents were tested in concentration ranges of 150–600 mg/L, 16.3–24.4%, and 140–500 mg/L, respectively. The starting substrates used were honeydew honey and 10% apple juice. Yeast was rehydrated and added in different amounts to obtain required concentrations. Initial dry matter concentrations were measured by a refractometer. At the end of fermentation, oenological parameters of mead, namely dry matter content, pH, and ethanol yield, were determined according to standard methods. Results and discussion. The statistical estimation of the developed model...
Energy production from biomass is gaining a lot of attention. Algal oil (microand macroalgae) can... more Energy production from biomass is gaining a lot of attention. Algal oil (microand macroalgae) can be used for biofuel production. Biofuels from this type of feedstock are called third generation biofuels or advanced biofuels. Focus of this paper is on the microalgal biofuels and on the available process technologies. Very important advantage of microalgal biofuels is that microalgae can be cultivated on any type of land, with the possibility of using wastewater streams. Microalgae can be cultivated in open systems, so called "raceway ponds" or in closed systems - photobioreactors: flat panel photobioreactors, horizontal tubular, vertical tubular photobioreactors with or without airlift. Also, basic information on cultivation conditions (photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic) are presented. Available technologies for microalgal biofuels production are: transesterification, fermentation, pyrolysis, hydrothermal liquefaction, anaerobic digestion ...
Post-consumer waste plastics that cannot be mechanically recycled represent a concerning environm... more Post-consumer waste plastics that cannot be mechanically recycled represent a concerning environmental issue. According to the latest available data for Europe, as much as 25% of collected post-consumer waste plastics are landfilled, 43% is energy recovered, and 32% is recycled. One possible way of recovering non-recyclable plastics is pyrolysis, which is considered environmentally friendly technology for obtaining fuel or chemicals from plastic waste. To tackle the challenge of recovering non-recyclable plastics via pyrolysis, it is necessary to determine their actual composition. Visual separation of collected non-recyclable plastics was performed, and Fourier-transform infrared spectroscopy was used to confirm the accuracy of visual separation. A significant amount of plastics labelled as "other" was found. Since the composition of "other" waste plastics has not been sufficiently investigated, relatively few studies on their pyrolysis have been conducted. Therefore, they were characterised and added to the mixture with other found polymer types of non-recyclable plastics. Thermogravimetric analysis was conducted to determine thermochemical behaviour and kinetic parameters required for laboratory pyrolysis investigation. Kinetic analysis was conducted using the Friedman isoconversional model-free method and non-linear multivariate regression method. The goal of this paper was to analyse the kinetics, determine the product yield and characteristics of the pyrolysis process of non-recyclable plastics over zeolite catalysts. It was found how the decomposition of non-recyclable plastics occurs in two decomposition steps. The activation energy of non-recyclable plastics was 144 kJ/mol in the first stage of decomposition and 262 kJ/mol in the second stage of decomposition. It decreased by 34% and 6.5% after fresh fluid catalytic cracking catalyst was added and 41% and 18.3% with iron-modified Zeolite Socony Mobil-5 catalyst. The yield of condensate was 55% (wax) for the original sample, and it decreased to 50% (wax and oil) and 27% (mostly oil) with fresh fluid catalytic cracking and iron modified Zeolite Socony Mobil-5 catalysts. Processes with catalysts promoted the formation of olefins and aromatic compounds in pyrolytic oil. All pyrolysis products had a high value of higher heating value ranging from 39 MJ/kg to 43 MJ/kg showing good potential for further energy use.
Multi-layered and mixed resin types of plastics are a great challenge for the waste recycling ind... more Multi-layered and mixed resin types of plastics are a great challenge for the waste recycling industry. The majority consist of two or more types of polymers, making it difficult to recycle mechanically, which leads to landfill or incineration plant. As a way of thermochemical recycling, pyrolysis is a promising cleaner technology that could use this plastics waste stream potential and convert it into valuable products like fuels. The hypotheses of this research are that the average apparent activation energy of multi-layered and mixed resin plastic real-world waste samples can be decreased with the addition of selected iron-modified zeolite catalyst and that catalytic pyrolysis in fixed bed reactor will give products that show good potential for use as an energy vector. To evaluate activation energy, kinetic analysis was conducted using the isoconversional model-free Friedman model in conjunction with the multivariate nonlinear regression method. Pyrolysis products were analysed using nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and calorimetry. The catalyst significantly reduced the activation energy of the flexible plastic film sample, which means that the process with catalyst requires less energy consumption. In the case of rigid plastics, the activation energy was lower at the beginning of the process with the catalyst. The catalyst reduced pyrolytic condensates’ viscosity of both samples. Analyses revealed how catalyst promoted the formation of aliphatic compounds in flexible plastics film oil, monoaromatic compounds in rigid plastics oil, and a significant decrease in polyaromatic compounds that degrade the quality of the fuel. The values of higher heating value were high (36–42 MJ/kg). Finally, the pyrolytic oil composition revealed satisfying quality and good potential for further use as an energy vector due to the high higher heating value.
The concept of Resource Efficient and Cleaner Production (RECP) focuses on a more cost‐effective ... more The concept of Resource Efficient and Cleaner Production (RECP) focuses on a more cost‐effective production while effectively solve the problem of environmental pollution. This article presents the RECP methodology in the case of industrial production of the bentonite. Aspects of production and management to which it is possible to apply the specific methods, that is, RECP measures were analyzed. Mass and energy balance of the process as a whole were prepared and concrete measures were proposed. Applying the proposed measures increases the efficiency of the whole process. This is expressed as absolute and relative RECP Indicators. Relative indicators show an increase in energy productivity of 16.34%, an increase in materials and water productivity of 1.72%, and a decrease in the intensity of emissions of solid waste from 59.5%, carbon (CO2‐eq) of 7.78%, and wastewater of 1.69%. Expressed as absolute indicators, achieved benefits are: energy use reduction in the amount of 3,438,367.2...
Bioenergy, or energy derived from biomass, today is recognized as an important component in many ... more Bioenergy, or energy derived from biomass, today is recognized as an important component in many energy scenarios, being an integral part of various global, regional, and national policies and strategies. This has led to intensified research into more efficient biofuel production. This paper explains the advantages, disadvantages, and problems related to the production of biofuels from different types of raw materials. Several examples of commercialized and demonstration plants for the production of biofuels in different parts of the world are listed. It is to be expected that, with greater use of modern biofuel production solutions, the contribution of these sources of (bio)energy will be the main part of future energy consumption from renewable sources.
Torrefaction is a thermochemical process, where biomass is obtained in temperature range from fro... more Torrefaction is a thermochemical process, where biomass is obtained in temperature range from from 200 to 300 °C, in inert atmosphere with the aim to increase carbon content of biomass. In this paper, emphasis is on biomass feedstock types, different effects on torrefaction success, and torrefaction reactors.
Wood ash is a complex mixture of inorganic and organic compounds. It is heterogeneous in composit... more Wood ash is a complex mixture of inorganic and organic compounds. It is heterogeneous in composition, which can vary considerably. Ash is mainly disposed of in landfills, which creates a risk for air, soil and groundwater contamination by trace elements. In order for wood biomass ash to be used as a secondary raw material, it is necessary to perform leaching tests, to determine which microelements it contains, and which of them could be released into the environment during the ash disposal. Sequential extraction (SE) showed that in the exchangeable and carbonate fraction, the most volatile metals As, Cd, Zn and Pb are released the most from the ash of deciduous trees, while the leaching of ash from coniferous trees is significantly lower. The evaluation of risk assessment code (RAC) for the tested biomass ash samples, indicates that Pb is a high-risk leaching element due to its condensation on the ash particles. By performing toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) tests, it was established that the released concentrations of tested metals are below the maximum allowable concentration, given by the regulation. The leaching tests of composites, prepared from wood ash in combination with cement, indicate that the leaching of ash is reduced to a minimum, and that all heavy metals are bound in a cement matrix, which indicates the possibility of using wood ash for construction purposes.
DOAJ (DOAJ: Directory of Open Access Journals), Jul 1, 2009
Today, rotary dryers are often use to dry sawdust prior to their further processing, palletizing ... more Today, rotary dryers are often use to dry sawdust prior to their further processing, palletizing and briquetting, into commercially voluble product. This paper present mathematical model for drying process of sawdust particles in a triple pass rotary dryer. As basis for this model, we used existing mathematical models for drying of sawdust and other biological materials in a single pass rotary dryer, which are modified and extended in order to satisfy mathematical description of motion of material in the triple pass rotary dryer. Developed mathematical model is used as basis for further developing of the simulation model that predict temperature and moisture profile sawdust and drying along the dryer. In order to solve and validate developed rotary dryer model, commercial triple pass rotary dryer, installed in enterprise Panensa near town of Srbac, have been analysed, and measured sawdust drying data have been used for comparison. Comparison between predicted and the measured results were good. Mathematical model i.e. rotary dryer simulation model developed in this paper is going to enable better management and controlling of process in the mentioned commercial rotary dryer as well as in other rotary dryers for wood waste with modification of appropriate model parameters
There is an urgent need for replacement of fossil fuels worldwide. Raw biomass has a low energy d... more There is an urgent need for replacement of fossil fuels worldwide. Raw biomass has a low energy density, contains too much moisture, can rot, and it is hygroscopic. This paper presents a very prominent thermal technology that could overcome mentioned deficiencies of raw biomass. This technology is known as torrefaction. Torrefaction is mainly used to convert lignocellulosic materials into 'fuels' that can be used in power plants, combustion units, or gasifiers.
The negative impact of climate change, especially in urban areas, requires the use of new constru... more The negative impact of climate change, especially in urban areas, requires the use of new construction technologies and materials, harmonized with environmental aspects. One such approach is the construction of green areas on flat roofs of buildings. The positive impact of greening roofs is reflected in several important aspects: environmental, economic, and social. The pilot area that was researched is characterized by a high coefficient of construction. All this affects the creation of the so‐called heat island and bad microclimatic conditions, as well as the lack of areas that can be arranged for the rest of the local population. In addition to the impact of this type of urban planning on the preservation of the city's environment, the costs of building green roofs are also presented. In the final part of the article, the life cycle impact assessment (LCIA) of green roof layers is presented, using the Eco‐indicator method to show the environmental impact of a materials based ...
The estimation of growth or inactivation of bacterial population in fruits during preservation an... more The estimation of growth or inactivation of bacterial population in fruits during preservation and storage provides useful information for the improvement of the safety of fresh-cut fruits and vegetables. This paper addressed the attachment to the surface and the growth in the flesh of apple fruits of four bacterial cultures (Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa). The growth of the bacterial cultures in apple flesh was monitored at particular time intervals, and Gompertz parameters, i.e. maximum number of bacteria (Pm), the maximum growth rate of bacteria rp,m, and lag time tl, were used to determine the growth kinetics. After the immersion, the highest number of P. aeruginosa and the lowest number of B. cereus adhered to the apples. After washing and swabbing, E. coli was reduced from the surface of apples to the highest extent (by 3.34 log cfu g-1), while the number of B. cereus was reduced to the lowest extent (1.66 log cfu g-1). Fitted curves of the Gompertz model corresponded quite well to the measured values of the number of microorganisms with R2 = 0.92-0.98. The values of the standard error (0.17-0.37) and extremely low p values of the Fischer test (p < 0.0001) indicated strict dependence between the model predicted and the maximum population density. The predicted values of the maximum number of microorganisms (Pm) correspond almost exactly to the actual values. A similar conclusion can be drawn for the maximum growth rate of microorganisms (rp,m), with the measured value being slightly higher than predicted values.
Introduction. This article presents the development of mathematical models related to the effect ... more Introduction. This article presents the development of mathematical models related to the effect of the initial content of dry matter, yeast, and yeast energizer on the fermentation rate, the alcohol content, and the dry matter content in the finished product – mead. Study objects and methods. The mathematical models were developed by using the response surface methodology (RSM). The effect of yeast, dry matter, and yeast energizer contents were tested in concentration ranges of 150–600 mg/L, 16.3–24.4%, and 140–500 mg/L, respectively. The starting substrates used were honeydew honey and 10% apple juice. Yeast was rehydrated and added in different amounts to obtain required concentrations. Initial dry matter concentrations were measured by a refractometer. At the end of fermentation, oenological parameters of mead, namely dry matter content, pH, and ethanol yield, were determined according to standard methods. Results and discussion. The statistical estimation of the developed model...
Energy production from biomass is gaining a lot of attention. Algal oil (microand macroalgae) can... more Energy production from biomass is gaining a lot of attention. Algal oil (microand macroalgae) can be used for biofuel production. Biofuels from this type of feedstock are called third generation biofuels or advanced biofuels. Focus of this paper is on the microalgal biofuels and on the available process technologies. Very important advantage of microalgal biofuels is that microalgae can be cultivated on any type of land, with the possibility of using wastewater streams. Microalgae can be cultivated in open systems, so called "raceway ponds" or in closed systems - photobioreactors: flat panel photobioreactors, horizontal tubular, vertical tubular photobioreactors with or without airlift. Also, basic information on cultivation conditions (photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic) are presented. Available technologies for microalgal biofuels production are: transesterification, fermentation, pyrolysis, hydrothermal liquefaction, anaerobic digestion ...
Post-consumer waste plastics that cannot be mechanically recycled represent a concerning environm... more Post-consumer waste plastics that cannot be mechanically recycled represent a concerning environmental issue. According to the latest available data for Europe, as much as 25% of collected post-consumer waste plastics are landfilled, 43% is energy recovered, and 32% is recycled. One possible way of recovering non-recyclable plastics is pyrolysis, which is considered environmentally friendly technology for obtaining fuel or chemicals from plastic waste. To tackle the challenge of recovering non-recyclable plastics via pyrolysis, it is necessary to determine their actual composition. Visual separation of collected non-recyclable plastics was performed, and Fourier-transform infrared spectroscopy was used to confirm the accuracy of visual separation. A significant amount of plastics labelled as "other" was found. Since the composition of "other" waste plastics has not been sufficiently investigated, relatively few studies on their pyrolysis have been conducted. Therefore, they were characterised and added to the mixture with other found polymer types of non-recyclable plastics. Thermogravimetric analysis was conducted to determine thermochemical behaviour and kinetic parameters required for laboratory pyrolysis investigation. Kinetic analysis was conducted using the Friedman isoconversional model-free method and non-linear multivariate regression method. The goal of this paper was to analyse the kinetics, determine the product yield and characteristics of the pyrolysis process of non-recyclable plastics over zeolite catalysts. It was found how the decomposition of non-recyclable plastics occurs in two decomposition steps. The activation energy of non-recyclable plastics was 144 kJ/mol in the first stage of decomposition and 262 kJ/mol in the second stage of decomposition. It decreased by 34% and 6.5% after fresh fluid catalytic cracking catalyst was added and 41% and 18.3% with iron-modified Zeolite Socony Mobil-5 catalyst. The yield of condensate was 55% (wax) for the original sample, and it decreased to 50% (wax and oil) and 27% (mostly oil) with fresh fluid catalytic cracking and iron modified Zeolite Socony Mobil-5 catalysts. Processes with catalysts promoted the formation of olefins and aromatic compounds in pyrolytic oil. All pyrolysis products had a high value of higher heating value ranging from 39 MJ/kg to 43 MJ/kg showing good potential for further energy use.
Multi-layered and mixed resin types of plastics are a great challenge for the waste recycling ind... more Multi-layered and mixed resin types of plastics are a great challenge for the waste recycling industry. The majority consist of two or more types of polymers, making it difficult to recycle mechanically, which leads to landfill or incineration plant. As a way of thermochemical recycling, pyrolysis is a promising cleaner technology that could use this plastics waste stream potential and convert it into valuable products like fuels. The hypotheses of this research are that the average apparent activation energy of multi-layered and mixed resin plastic real-world waste samples can be decreased with the addition of selected iron-modified zeolite catalyst and that catalytic pyrolysis in fixed bed reactor will give products that show good potential for use as an energy vector. To evaluate activation energy, kinetic analysis was conducted using the isoconversional model-free Friedman model in conjunction with the multivariate nonlinear regression method. Pyrolysis products were analysed using nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and calorimetry. The catalyst significantly reduced the activation energy of the flexible plastic film sample, which means that the process with catalyst requires less energy consumption. In the case of rigid plastics, the activation energy was lower at the beginning of the process with the catalyst. The catalyst reduced pyrolytic condensates’ viscosity of both samples. Analyses revealed how catalyst promoted the formation of aliphatic compounds in flexible plastics film oil, monoaromatic compounds in rigid plastics oil, and a significant decrease in polyaromatic compounds that degrade the quality of the fuel. The values of higher heating value were high (36–42 MJ/kg). Finally, the pyrolytic oil composition revealed satisfying quality and good potential for further use as an energy vector due to the high higher heating value.
The concept of Resource Efficient and Cleaner Production (RECP) focuses on a more cost‐effective ... more The concept of Resource Efficient and Cleaner Production (RECP) focuses on a more cost‐effective production while effectively solve the problem of environmental pollution. This article presents the RECP methodology in the case of industrial production of the bentonite. Aspects of production and management to which it is possible to apply the specific methods, that is, RECP measures were analyzed. Mass and energy balance of the process as a whole were prepared and concrete measures were proposed. Applying the proposed measures increases the efficiency of the whole process. This is expressed as absolute and relative RECP Indicators. Relative indicators show an increase in energy productivity of 16.34%, an increase in materials and water productivity of 1.72%, and a decrease in the intensity of emissions of solid waste from 59.5%, carbon (CO2‐eq) of 7.78%, and wastewater of 1.69%. Expressed as absolute indicators, achieved benefits are: energy use reduction in the amount of 3,438,367.2...
Bioenergy, or energy derived from biomass, today is recognized as an important component in many ... more Bioenergy, or energy derived from biomass, today is recognized as an important component in many energy scenarios, being an integral part of various global, regional, and national policies and strategies. This has led to intensified research into more efficient biofuel production. This paper explains the advantages, disadvantages, and problems related to the production of biofuels from different types of raw materials. Several examples of commercialized and demonstration plants for the production of biofuels in different parts of the world are listed. It is to be expected that, with greater use of modern biofuel production solutions, the contribution of these sources of (bio)energy will be the main part of future energy consumption from renewable sources.
Torrefaction is a thermochemical process, where biomass is obtained in temperature range from fro... more Torrefaction is a thermochemical process, where biomass is obtained in temperature range from from 200 to 300 °C, in inert atmosphere with the aim to increase carbon content of biomass. In this paper, emphasis is on biomass feedstock types, different effects on torrefaction success, and torrefaction reactors.
Wood ash is a complex mixture of inorganic and organic compounds. It is heterogeneous in composit... more Wood ash is a complex mixture of inorganic and organic compounds. It is heterogeneous in composition, which can vary considerably. Ash is mainly disposed of in landfills, which creates a risk for air, soil and groundwater contamination by trace elements. In order for wood biomass ash to be used as a secondary raw material, it is necessary to perform leaching tests, to determine which microelements it contains, and which of them could be released into the environment during the ash disposal. Sequential extraction (SE) showed that in the exchangeable and carbonate fraction, the most volatile metals As, Cd, Zn and Pb are released the most from the ash of deciduous trees, while the leaching of ash from coniferous trees is significantly lower. The evaluation of risk assessment code (RAC) for the tested biomass ash samples, indicates that Pb is a high-risk leaching element due to its condensation on the ash particles. By performing toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) tests, it was established that the released concentrations of tested metals are below the maximum allowable concentration, given by the regulation. The leaching tests of composites, prepared from wood ash in combination with cement, indicate that the leaching of ash is reduced to a minimum, and that all heavy metals are bound in a cement matrix, which indicates the possibility of using wood ash for construction purposes.
Uploads