The main objective of this work was to further analyze the optimization of the production factors... more The main objective of this work was to further analyze the optimization of the production factors of Arundo donax L. fiberboards obtained without adhesives. The production of boards derived from Arundo donax L. without added adhesives and with high mechanical performance has already been demonstrated. This present study explored a modification in the production process through a final curing thermal treatment (final heat treatment, FHT). Since pressing time is an influential factor in the production cost, it is expected that curing allows a reduction of this time. This study compared the results obtained by three panel-production alternatives: long pressing time (tp) without curing and long and short tp with FHT. Of the two factors analyzed, pressing pressure (Pp) was the most important production factor in both the modulus of elasticity (MOE) and modulus of rupture (MOR), while curing was the most important factor for the internal bond (IB). The study shows that a FHT facilitates t...
The aim of this study is to explore an innovative downstream route for microalgae processing to r... more The aim of this study is to explore an innovative downstream route for microalgae processing to reduce cost production. Experiments have been carried out on cell disruption and fractionation stages to recover lipids, sugars, and proteins. Steam explosion and dynamic membrane filtration were used as unit operations. The species tested were Nannochloropsis gaditana, Chlorella sorokiniana, and Dunaliella tertiolecta with different cell wall characteristics. Acid-catalysed steam explosion permitted cell disruption, as well as the hydrolysis of carbohydrates and partial hydrolysis of proteins. This permitted a better access to non-polar solvents for lipid extraction. Dynamic filtration was used to moderate the impact of fouling. Filtration enabled two streams: A permeate containing water and monosaccharides and a low-volume retentate containing the lipids and proteins. The necessary volume of solvent to extract the lipids is thus much lower. An estimation of operational costs of both steam explosion and membrane filtration was performed. The results show that the steam explosion operation cost varies between 0.
Abstract The present work focuses on the application of pH-induced sedimentation combined with dy... more Abstract The present work focuses on the application of pH-induced sedimentation combined with dynamic filtration for microalgae culture concentration at pilot scale. Concentrations were performed on cultures of two microalgae species: Dunaliella tertiolecta and Chlorella sorokiniana . The objective of the combined process was to reduce microalgae dewatering costs. It is true that sedimentation reduces operation costs considerably, but the results of membrane filtration offer a total rejection and high final concentrations, at even a cheaper cost than centrifugation. When using the two technologies in series, high concentration factors with values up to 207.4 for Dunaliella tertiolecta and 245.3 for Chlorella sorokiniana were achieved. The final concentration of Dunaliella tertiolecta was 184.58 g L −1 with 81.5% of water content in the sludge. The concentrations obtained were high enough to dispense with further operations for the sludge to be ready for a cell disruption step using steam explosion. Analytic techniques used were dry weight and optical density. For the filtration, experiments were performed using both commercially available and self-prepared membranes, manufactured from Acrylonitrile Butadiene Styrene: a novel polymer in membrane technology, selected to reduce costs. Each of them could perform in a similar way to commercial membranes in a pilot scale high-shear stress membrane module.
Abstract A membrane reactor containing an immobilized heterogeneous catalyst is an alternative fo... more Abstract A membrane reactor containing an immobilized heterogeneous catalyst is an alternative for traditional homogeneous-based catalyzed transesterification for biodiesel production. Major problems in homogeneous catalysis are related to catalyst recuperation and soap formation, which can be overcome by using heterogeneous catalysts. Conversion can be increased by a combination of reaction and separation, using membranes with a specific pore size. The aim of this work was to study the performance of different membrane reactors combined with heterogeneous catalysis. The main objectives were: to identify a proper catalyst, to choose the proper immobilization technique, to establish the membrane with the adequate pore size, and to control the reaction and separation process. Amberlyst®15 with acid sites and different types of strontium oxide with basic sites were tested as heterogeneous catalysts. Strontium oxide provided the highest sunflower oil conversion (around 93%) and was easy to immobilize. Two catalytic membrane reactor configurations were investigated, thus confirming the production of several types of methyl esters. The configuration comprising the physical immobilization of the catalyst over the membrane reached a methyl ester yield of > 90 wt%.
This paper explores the possibility of producing all-lignocellulosic fiberboards from L. as a sou... more This paper explores the possibility of producing all-lignocellulosic fiberboards from L. as a source of lignocellulosic fibers with no synthetic binders. This raw material was steam exploded with a thermomechanical aqueous vapor process in a batch reactor. The raw material and its obtained pulp were characterized in terms of chemical composition and the results were compared to other lignocellulosic materials. The chemical composition of steam exploded fibers showed high cellulose and a moderate lignin content suggesting it was a good raw material for fiberboard production. The all-lignocellulosic fiberboards were produced on laboratory scale; using the steam exploded by means of a wet process. The effects of pressing pressure on physical and mechanical properties were evaluated and the conditions that optimize the responses were found. The analyzed properties were density (d); water absorption (WA); thickness swelling (TS); modulus of elasticity (MOE); modulus of rupture (MOR); and...
El biodiesel es un combustible basado en ésteres metílicos de ácidos grasos con numerosas ventaja... more El biodiesel es un combustible basado en ésteres metílicos de ácidos grasos con numerosas ventajas ambientales. Una de las más importantes es su elevada biodegradabilidad y su habilidad para disolver el petróleo crudo. En este estudio, se prepararon mezclas de petróleo crudo pesado y biodiesel y se midieron las densidades y viscosidades de dichas mezclas con el fin de evaluar la facilidad de recolección de las mismas en una zona afectada por un derrame. Se encontró que la densidad de todas las muestras estaba por debajo de la densidad del agua de mar, lo que indica que estas flotarán en la superficie. La viscosidad de las mezclas fue inferior varios órdenes de magnitud con respecto a la viscosidad del petróleo crudo pesado; esto indica la posibilidad de bombear fácilmente las mismas. Adicionalmente, se estudió la biodegradabilidad de las mezclas mediante el método de evolución de CO2. En todos los casos, la biodegradabilidad se incrementó con la adición del biodiesel y mostró la pre...
Miniaturized cells can be used in photo-electrochemistry to perform water splitting. The geometry... more Miniaturized cells can be used in photo-electrochemistry to perform water splitting. The geometry, process variables and removal of oxygen bubbles in these cells need to be optimized. Bubbles tend to remain attached to the catalytic surface, thus blocking the reaction, and they therefore need to be dragged out of the cell. Computational Fluid Dynamics simulations have been carried out to assess the design of miniaturized cells and their results have been compared with experimental results. It has been found that low liquid inlet velocities (~0.1 m/s) favor the homogeneous distribution of the flow. Moderate velocities (0.5-1 m/s) favor preferred paths. High velocities (~2 m/s) lead to turbulent behavior of the flow, but avoid bubble coalescence and help to drag the bubbles. Gravity has a limited effect at this velocity. Finally, channeled cells have also been analyzed and they allow a good flow distribution, but part of the catalytic area could be lost. The here presented results can be used as guidelines for the optimum design of photocatalytic cells for the water splitting reaction for the production of solar fuels, such as H 2 or other CO 2 reduction products (i.e., CO, CH 4 , among others).
Arundo donax is a cane species with high growing productivity, and it is becoming an important so... more Arundo donax is a cane species with high growing productivity, and it is becoming an important source of biomass. The main objective of this study was to obtain fibreboards with high mechanical performance from A. donax without any added adhesive. Boards made without adhesive are free from formaldehyde emissions and consume no fossil resources. The characteristics of the obtained boards depended on the original material, steam explosion pre-treatments, and forming conditions (pressure, temperature, and pressing time). Production parameters were optimized. The effect of forming pressure on the physical and mechanical properties density, elastic modulus (MOE), modulus of rupture (MOR), tensile strength perpendicular to the faces (IB), thickness swelling, and water absorption of the obtained boards was studied. The European Norms (EN) methodologies were used to test the board specifications. Density, MOE, and MOR were modelled by a double reciprocal function. TS and WA were modelled with a reciprocal function in X. The boards obtained met and sometimes exceeded the requirements of these standards for the most demanding structural use.
The biomass, generated after the lipid extraction from Nannochloropsis microalgae (LEM) for biodi... more The biomass, generated after the lipid extraction from Nannochloropsis microalgae (LEM) for biodiesel production, demonstrated its suitability for both energy and nutrient recovery. The anaerobic digestion of LEM produced a minimum of 268 mL CH4 /g VS in different experiments. The codigestion of LEM and sewage sludge revealed that both wastes can be codigested without inhibition, although no synergy was observed. The methane yields barely increased 10% after pretreatments (ultrasound and ultrasound combined with alkali addition). Regarding bio-oil production from hydrothermal liquefaction process, more than 28% of the LEM was converted into bio-oil. Moreover, the aqueous phase generated during the bio-oil production was successfully utilized as nitrogen source for microalgae cultivation.
Lignin was used as a natural adhesive to manufacture Vitis vinifera fiberboards. The fiberboards ... more Lignin was used as a natural adhesive to manufacture Vitis vinifera fiberboards. The fiberboards were produced at laboratory scale by adding powdered lignin to material that had previously been steamexploded under optimized pretreatment and pressing conditions. The kraft lignin used was washed several times with an acidic solution to eliminate any contaminants and low molecular weight compounds. This research studied the effects of amounts of lignin ranging from 5% to 20% on the properties of Vitis vinifera fiberboards. The fiberboard properties evaluated were density, water resistance in terms of thickness swelling, water absorption, and the mechanical properties in terms of modulus of rupture, modulus of elasticity, and internal bond. Results showed that fiberboards made from Vitis vinifera without lignin addition had weaker mechanical properties. However, the fiberboards obtained using acidwashed kraft lignin as a natural adhesive had good mechanical and water resistance properties that fully satisfied the relevant standard specifications.
A strategy to reduce costs in the microalgae dewatering process via membrane cross-flow filtratio... more A strategy to reduce costs in the microalgae dewatering process via membrane cross-flow filtration was investigated in this work. It consisted in assessing the possibilities of reduce membrane material cost. Several membrane materials, from commonly used in membrane technology (ceramic, polysulfone and polyacrylonitrile) to generally employed in packaging industry (acrylonitrile butadiene styrene, glycol-modified polyethylene terephthalate and polylactide) were tested. Where, last ones are considerably cheaper than common ones. Experiments carried out showed interesting results in terms of permeabilities for polysulfone-Pluronic® F127 blended membranes and polyacrylonitrile membranes, but with high related costs. Polylactide membranes had good price, mechanical properties results and biodegradability, but low permeability values. Glycol-modified polyethylene terephthalate
Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from ... more Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from algae. This paper presents experimental results for a cost-effective system to harvest Chaetoceros calcitrans, using natural sedimentation; flocculation; and inducing pH. No efficient sedimentation of microalgae cells was observed only by gravity. By alkalinity induced flocculation, at pH value of 9.51, 86% recovery of the cells achieved with sedimentation rate 125 cm/h and concentration factor 4 (volume/volume; v/v) in 10 minutes. The maximum photochemical quantum yield of PSII (Fv/Fm) of concentrated cells was almost the same as fresh culture (0.621). Commercial flocculants, aluminum sulfate and poly aluminum chloride, were also successful in harvesting the studied algae cells. Optimum concentration of AS could be concluded as 10 ppm with 87.6% recovery and 7.10 concentration factor (v/v) in 30 min for cost efficient harvesting, whereas for PAC 20 ppm with 74% recovery and 6.6 concentr...
ABSTRACT A microalgal growth model has been developed based upon experiments using three species ... more ABSTRACT A microalgal growth model has been developed based upon experiments using three species – (Cylindrotheca closterium, Nannochloropsis gaditana and Phaeodactylum tricornutum) – at three different levels of carbon dioxide (provided by aeration with ambient air, ambient air enriched with 0.5% carbon dioxide, and ambient air enriched with 1% carbon dioxide). We used a two-step growth model for phytoplankton comprising first uptake of the nutrients (C, N and P) and then growth based on the intracellular concentrations of the three nutrients. In addition, the model considered the fraction of cellular carbon that is lipid. The model did not require calibration, as the parameters were based on literature values, allometric principles and direct measurements. The validation of the model gave acceptable results. Based upon both the model itself and experimental results for P. tricornutum, it can be concluded that higher content of organic carbon and lipid would not be obtained by further addition of carbon dioxide beyond 0.5–1%. The production of organic carbon by this species with addition of 1% carbon dioxide could be about 90 mg/l in 24 h, which is consistent with other production results from the literature.
Lignins were obtained from a mixture of softwood sawdust using a hydrolytic pretreatment and a su... more Lignins were obtained from a mixture of softwood sawdust using a hydrolytic pretreatment and a subsequent soda-anthraquinone delignification/pulping stage. Their potential uses and the effect of the pretreatment conditions on the yield (% of recovered lignin from black ...
This paper studies the feasibility of incorporating treated lignins in fiberboards made from Viti... more This paper studies the feasibility of incorporating treated lignins in fiberboards made from Vitis vinifera as an agricultural waste. The treated lignins are the purified Kraft lignin and the alkaline hydrolyzed Kraft lignin. V. vinifera raw material and its fibers were characterized in terms of chemical composition and the results were compared to other biomass species. The chemical composition of treated lignins shows that they have high purity compared to the lignin raw material. The lignin-V. vinifera fibreboards were produced on laboratory scale by adding powdered treated lignins to the material that had previously been steam exploded. Some of the important properties of fibreboards prepared using the treated lignins as natural adhesives were evaluated. These properties were density, thickness swelling, water absorption, modulus of elasticity, modulus of rupture, internal bond strength. The explored levels of treated lignins vary from 5% to 20%. The results showed that binderless fibreboards, fibreboards made from V. vinifera fibers and alkaline hydrolyzed Kraft lignin have weaker mechanical properties. However, the fibreboards obtained using purified Kraft lignin have good mechanical and water resistance properties which satisfy the requirements of the relevant standards specifications.
The main objective of this work was to further analyze the optimization of the production factors... more The main objective of this work was to further analyze the optimization of the production factors of Arundo donax L. fiberboards obtained without adhesives. The production of boards derived from Arundo donax L. without added adhesives and with high mechanical performance has already been demonstrated. This present study explored a modification in the production process through a final curing thermal treatment (final heat treatment, FHT). Since pressing time is an influential factor in the production cost, it is expected that curing allows a reduction of this time. This study compared the results obtained by three panel-production alternatives: long pressing time (tp) without curing and long and short tp with FHT. Of the two factors analyzed, pressing pressure (Pp) was the most important production factor in both the modulus of elasticity (MOE) and modulus of rupture (MOR), while curing was the most important factor for the internal bond (IB). The study shows that a FHT facilitates t...
The aim of this study is to explore an innovative downstream route for microalgae processing to r... more The aim of this study is to explore an innovative downstream route for microalgae processing to reduce cost production. Experiments have been carried out on cell disruption and fractionation stages to recover lipids, sugars, and proteins. Steam explosion and dynamic membrane filtration were used as unit operations. The species tested were Nannochloropsis gaditana, Chlorella sorokiniana, and Dunaliella tertiolecta with different cell wall characteristics. Acid-catalysed steam explosion permitted cell disruption, as well as the hydrolysis of carbohydrates and partial hydrolysis of proteins. This permitted a better access to non-polar solvents for lipid extraction. Dynamic filtration was used to moderate the impact of fouling. Filtration enabled two streams: A permeate containing water and monosaccharides and a low-volume retentate containing the lipids and proteins. The necessary volume of solvent to extract the lipids is thus much lower. An estimation of operational costs of both steam explosion and membrane filtration was performed. The results show that the steam explosion operation cost varies between 0.
Abstract The present work focuses on the application of pH-induced sedimentation combined with dy... more Abstract The present work focuses on the application of pH-induced sedimentation combined with dynamic filtration for microalgae culture concentration at pilot scale. Concentrations were performed on cultures of two microalgae species: Dunaliella tertiolecta and Chlorella sorokiniana . The objective of the combined process was to reduce microalgae dewatering costs. It is true that sedimentation reduces operation costs considerably, but the results of membrane filtration offer a total rejection and high final concentrations, at even a cheaper cost than centrifugation. When using the two technologies in series, high concentration factors with values up to 207.4 for Dunaliella tertiolecta and 245.3 for Chlorella sorokiniana were achieved. The final concentration of Dunaliella tertiolecta was 184.58 g L −1 with 81.5% of water content in the sludge. The concentrations obtained were high enough to dispense with further operations for the sludge to be ready for a cell disruption step using steam explosion. Analytic techniques used were dry weight and optical density. For the filtration, experiments were performed using both commercially available and self-prepared membranes, manufactured from Acrylonitrile Butadiene Styrene: a novel polymer in membrane technology, selected to reduce costs. Each of them could perform in a similar way to commercial membranes in a pilot scale high-shear stress membrane module.
Abstract A membrane reactor containing an immobilized heterogeneous catalyst is an alternative fo... more Abstract A membrane reactor containing an immobilized heterogeneous catalyst is an alternative for traditional homogeneous-based catalyzed transesterification for biodiesel production. Major problems in homogeneous catalysis are related to catalyst recuperation and soap formation, which can be overcome by using heterogeneous catalysts. Conversion can be increased by a combination of reaction and separation, using membranes with a specific pore size. The aim of this work was to study the performance of different membrane reactors combined with heterogeneous catalysis. The main objectives were: to identify a proper catalyst, to choose the proper immobilization technique, to establish the membrane with the adequate pore size, and to control the reaction and separation process. Amberlyst®15 with acid sites and different types of strontium oxide with basic sites were tested as heterogeneous catalysts. Strontium oxide provided the highest sunflower oil conversion (around 93%) and was easy to immobilize. Two catalytic membrane reactor configurations were investigated, thus confirming the production of several types of methyl esters. The configuration comprising the physical immobilization of the catalyst over the membrane reached a methyl ester yield of > 90 wt%.
This paper explores the possibility of producing all-lignocellulosic fiberboards from L. as a sou... more This paper explores the possibility of producing all-lignocellulosic fiberboards from L. as a source of lignocellulosic fibers with no synthetic binders. This raw material was steam exploded with a thermomechanical aqueous vapor process in a batch reactor. The raw material and its obtained pulp were characterized in terms of chemical composition and the results were compared to other lignocellulosic materials. The chemical composition of steam exploded fibers showed high cellulose and a moderate lignin content suggesting it was a good raw material for fiberboard production. The all-lignocellulosic fiberboards were produced on laboratory scale; using the steam exploded by means of a wet process. The effects of pressing pressure on physical and mechanical properties were evaluated and the conditions that optimize the responses were found. The analyzed properties were density (d); water absorption (WA); thickness swelling (TS); modulus of elasticity (MOE); modulus of rupture (MOR); and...
El biodiesel es un combustible basado en ésteres metílicos de ácidos grasos con numerosas ventaja... more El biodiesel es un combustible basado en ésteres metílicos de ácidos grasos con numerosas ventajas ambientales. Una de las más importantes es su elevada biodegradabilidad y su habilidad para disolver el petróleo crudo. En este estudio, se prepararon mezclas de petróleo crudo pesado y biodiesel y se midieron las densidades y viscosidades de dichas mezclas con el fin de evaluar la facilidad de recolección de las mismas en una zona afectada por un derrame. Se encontró que la densidad de todas las muestras estaba por debajo de la densidad del agua de mar, lo que indica que estas flotarán en la superficie. La viscosidad de las mezclas fue inferior varios órdenes de magnitud con respecto a la viscosidad del petróleo crudo pesado; esto indica la posibilidad de bombear fácilmente las mismas. Adicionalmente, se estudió la biodegradabilidad de las mezclas mediante el método de evolución de CO2. En todos los casos, la biodegradabilidad se incrementó con la adición del biodiesel y mostró la pre...
Miniaturized cells can be used in photo-electrochemistry to perform water splitting. The geometry... more Miniaturized cells can be used in photo-electrochemistry to perform water splitting. The geometry, process variables and removal of oxygen bubbles in these cells need to be optimized. Bubbles tend to remain attached to the catalytic surface, thus blocking the reaction, and they therefore need to be dragged out of the cell. Computational Fluid Dynamics simulations have been carried out to assess the design of miniaturized cells and their results have been compared with experimental results. It has been found that low liquid inlet velocities (~0.1 m/s) favor the homogeneous distribution of the flow. Moderate velocities (0.5-1 m/s) favor preferred paths. High velocities (~2 m/s) lead to turbulent behavior of the flow, but avoid bubble coalescence and help to drag the bubbles. Gravity has a limited effect at this velocity. Finally, channeled cells have also been analyzed and they allow a good flow distribution, but part of the catalytic area could be lost. The here presented results can be used as guidelines for the optimum design of photocatalytic cells for the water splitting reaction for the production of solar fuels, such as H 2 or other CO 2 reduction products (i.e., CO, CH 4 , among others).
Arundo donax is a cane species with high growing productivity, and it is becoming an important so... more Arundo donax is a cane species with high growing productivity, and it is becoming an important source of biomass. The main objective of this study was to obtain fibreboards with high mechanical performance from A. donax without any added adhesive. Boards made without adhesive are free from formaldehyde emissions and consume no fossil resources. The characteristics of the obtained boards depended on the original material, steam explosion pre-treatments, and forming conditions (pressure, temperature, and pressing time). Production parameters were optimized. The effect of forming pressure on the physical and mechanical properties density, elastic modulus (MOE), modulus of rupture (MOR), tensile strength perpendicular to the faces (IB), thickness swelling, and water absorption of the obtained boards was studied. The European Norms (EN) methodologies were used to test the board specifications. Density, MOE, and MOR were modelled by a double reciprocal function. TS and WA were modelled with a reciprocal function in X. The boards obtained met and sometimes exceeded the requirements of these standards for the most demanding structural use.
The biomass, generated after the lipid extraction from Nannochloropsis microalgae (LEM) for biodi... more The biomass, generated after the lipid extraction from Nannochloropsis microalgae (LEM) for biodiesel production, demonstrated its suitability for both energy and nutrient recovery. The anaerobic digestion of LEM produced a minimum of 268 mL CH4 /g VS in different experiments. The codigestion of LEM and sewage sludge revealed that both wastes can be codigested without inhibition, although no synergy was observed. The methane yields barely increased 10% after pretreatments (ultrasound and ultrasound combined with alkali addition). Regarding bio-oil production from hydrothermal liquefaction process, more than 28% of the LEM was converted into bio-oil. Moreover, the aqueous phase generated during the bio-oil production was successfully utilized as nitrogen source for microalgae cultivation.
Lignin was used as a natural adhesive to manufacture Vitis vinifera fiberboards. The fiberboards ... more Lignin was used as a natural adhesive to manufacture Vitis vinifera fiberboards. The fiberboards were produced at laboratory scale by adding powdered lignin to material that had previously been steamexploded under optimized pretreatment and pressing conditions. The kraft lignin used was washed several times with an acidic solution to eliminate any contaminants and low molecular weight compounds. This research studied the effects of amounts of lignin ranging from 5% to 20% on the properties of Vitis vinifera fiberboards. The fiberboard properties evaluated were density, water resistance in terms of thickness swelling, water absorption, and the mechanical properties in terms of modulus of rupture, modulus of elasticity, and internal bond. Results showed that fiberboards made from Vitis vinifera without lignin addition had weaker mechanical properties. However, the fiberboards obtained using acidwashed kraft lignin as a natural adhesive had good mechanical and water resistance properties that fully satisfied the relevant standard specifications.
A strategy to reduce costs in the microalgae dewatering process via membrane cross-flow filtratio... more A strategy to reduce costs in the microalgae dewatering process via membrane cross-flow filtration was investigated in this work. It consisted in assessing the possibilities of reduce membrane material cost. Several membrane materials, from commonly used in membrane technology (ceramic, polysulfone and polyacrylonitrile) to generally employed in packaging industry (acrylonitrile butadiene styrene, glycol-modified polyethylene terephthalate and polylactide) were tested. Where, last ones are considerably cheaper than common ones. Experiments carried out showed interesting results in terms of permeabilities for polysulfone-Pluronic® F127 blended membranes and polyacrylonitrile membranes, but with high related costs. Polylactide membranes had good price, mechanical properties results and biodegradability, but low permeability values. Glycol-modified polyethylene terephthalate
Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from ... more Harvesting is one of the key challenges to determine the feasibility of producing biodiesel from algae. This paper presents experimental results for a cost-effective system to harvest Chaetoceros calcitrans, using natural sedimentation; flocculation; and inducing pH. No efficient sedimentation of microalgae cells was observed only by gravity. By alkalinity induced flocculation, at pH value of 9.51, 86% recovery of the cells achieved with sedimentation rate 125 cm/h and concentration factor 4 (volume/volume; v/v) in 10 minutes. The maximum photochemical quantum yield of PSII (Fv/Fm) of concentrated cells was almost the same as fresh culture (0.621). Commercial flocculants, aluminum sulfate and poly aluminum chloride, were also successful in harvesting the studied algae cells. Optimum concentration of AS could be concluded as 10 ppm with 87.6% recovery and 7.10 concentration factor (v/v) in 30 min for cost efficient harvesting, whereas for PAC 20 ppm with 74% recovery and 6.6 concentr...
ABSTRACT A microalgal growth model has been developed based upon experiments using three species ... more ABSTRACT A microalgal growth model has been developed based upon experiments using three species – (Cylindrotheca closterium, Nannochloropsis gaditana and Phaeodactylum tricornutum) – at three different levels of carbon dioxide (provided by aeration with ambient air, ambient air enriched with 0.5% carbon dioxide, and ambient air enriched with 1% carbon dioxide). We used a two-step growth model for phytoplankton comprising first uptake of the nutrients (C, N and P) and then growth based on the intracellular concentrations of the three nutrients. In addition, the model considered the fraction of cellular carbon that is lipid. The model did not require calibration, as the parameters were based on literature values, allometric principles and direct measurements. The validation of the model gave acceptable results. Based upon both the model itself and experimental results for P. tricornutum, it can be concluded that higher content of organic carbon and lipid would not be obtained by further addition of carbon dioxide beyond 0.5–1%. The production of organic carbon by this species with addition of 1% carbon dioxide could be about 90 mg/l in 24 h, which is consistent with other production results from the literature.
Lignins were obtained from a mixture of softwood sawdust using a hydrolytic pretreatment and a su... more Lignins were obtained from a mixture of softwood sawdust using a hydrolytic pretreatment and a subsequent soda-anthraquinone delignification/pulping stage. Their potential uses and the effect of the pretreatment conditions on the yield (% of recovered lignin from black ...
This paper studies the feasibility of incorporating treated lignins in fiberboards made from Viti... more This paper studies the feasibility of incorporating treated lignins in fiberboards made from Vitis vinifera as an agricultural waste. The treated lignins are the purified Kraft lignin and the alkaline hydrolyzed Kraft lignin. V. vinifera raw material and its fibers were characterized in terms of chemical composition and the results were compared to other biomass species. The chemical composition of treated lignins shows that they have high purity compared to the lignin raw material. The lignin-V. vinifera fibreboards were produced on laboratory scale by adding powdered treated lignins to the material that had previously been steam exploded. Some of the important properties of fibreboards prepared using the treated lignins as natural adhesives were evaluated. These properties were density, thickness swelling, water absorption, modulus of elasticity, modulus of rupture, internal bond strength. The explored levels of treated lignins vary from 5% to 20%. The results showed that binderless fibreboards, fibreboards made from V. vinifera fibers and alkaline hydrolyzed Kraft lignin have weaker mechanical properties. However, the fibreboards obtained using purified Kraft lignin have good mechanical and water resistance properties which satisfy the requirements of the relevant standards specifications.
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