• Energy Research

Abstract Microalgal biomass is one of the most promising third-generation feedstocks for bioethanol production because it contains significantly reduced sugar amounts which, by separate hydrolysis and fermentation, can be used as a source for ethanol production. In this study, the defatted microalgal biomass of Nannochloropsis oculata (NNO-1 UTEX Culture LB 2164) was subjected to bioethanol production through acid digestion and enzymatic treatment before being fermented by Saccharomyces cerevisiae (NRRLY-2034). For acid hydrolysis (AH), the highest carbohydrate yield 252.84 mg/g DW was obtained with 5.0% (v/v) H2SO4 at 121°C for 15 min for defatted biomass cultivated mixotrophically on SBAE with respect to 207.41 mg/g DW for defatted biomass cultivated autotrophically (control treatment), Whereas, the highest levels of reducing sugars was obtained With 4.0%(v/v) H2SO4 157.47 ± 1.60 mg/g DW for defatted biomass cultivated mixotrophically in compared with 135.30 mg/g DW for the defatted control treatment. The combination of acid hydrolysis 2.0% (v/v) H2SO4 followed by enzymatic treatment (AEH) increased the carbohydrate yields to 268.53 mg/g DW for defatted biomass cultivated mixotrophically on SBAE with respect to 177.73 mg/g DW for the defatted control treatment. However, the highest levels of reducing sugars were obtained with 3.0% (v/v) H2SO4 followed by enzyme treatment gave 232.39 ± 1.77 for defatted biomass cultivated mixotrophically on SBAE and 150.75 mg/g DW for the defatted control treatment. The sugar composition of the polysaccharides showed that glucose was the principal polysaccharide sugar (60.7%-62.49%) of N. oculata defatted biomass. Fermentation of the hydrolysates by Saccharomyces cerevisiae for the acid pretreated defatted biomass samples gave ethanol yield of 0.86 g/l (0.062 g/g sugar consumed) for control and 1.17 g/l (0.069 g/g sugar consumed) for SBAE mixotrophic. Whereas, the maximum ethanol yield of 6.17 ± 0.47 g/l (0.26 ± 0.11 g/g sugar consumed) was obtained with samples from defatted biomass grown mixotrophically (SBAE mixotrophic) pretreated with acid coupled enzyme hydrolysis.

Abstract Microalgal biomass is one of the most promising third-generation feedstocks for bioethanol production because it contains significantly reduced sugar amounts which, by separate hydrolysis and fermentation, can be used as a source for ethanol production. In this study, the defatted microalgal biomass of Nannochloropsis oculata (NNO-1 UTEX Culture LB 2164) was subjected to bioethanol production through acid digestion and enzymatic treatment before being fermented by Saccharomyces cerevisiae (NRRLY-2034). For acid hydrolysis (AH), the highest carbohydrate yield 252.84 mg/g DW was obtained with 5.0% (v/v) H2SO4 at 121°C for 15 min for defatted biomass cultivated mixotrophically on SBAE with respect to 207.41 mg/g DW for defatted biomass cultivated autotrophically (control treatment), Whereas, the highest levels of reducing sugars was obtained With 4.0%(v/v) H2SO4 157.47 ± 1.60 mg/g DW for defatted biomass cultivated mixotrophically in compared with 135.30 mg/g DW for the defatted control treatment. The combination of acid hydrolysis 2.0% (v/v) H2SO4 followed by enzymatic treatment (AEH) increased the carbohydrate yields to 268.53 mg/g DW for defatted biomass cultivated mixotrophically on SBAE with respect to 177.73 mg/g DW for the defatted control treatment. However, the highest levels of reducing sugars were obtained with 3.0% (v/v) H2SO4 followed by enzyme treatment gave 232.39 ± 1.77 for defatted biomass cultivated mixotrophically on SBAE and 150.75 mg/g DW for the defatted control treatment. The sugar composition of the polysaccharides showed that glucose was the principal polysaccharide sugar (60.7%-62.49%) of N. oculata defatted biomass. Fermentation of the hydrolysates by Saccharomyces cerevisiae for the acid pretreated defatted biomass samples gave ethanol yield of 0.86 g/l (0.062 g/g sugar consumed) for control and 1.17 g/l (0.069 g/g sugar consumed) for SBAE mixotrophic. Whereas, the maximum ethanol yield of 6.17 ± 0.47 g/l (0.26 ± 0.11 g/g sugar consumed) was obtained with samples from defatted biomass grown mixotrophically (SBAE mixotrophic) pretreated with acid coupled enzyme hydrolysis.

Abstract Recently, the use of nanomaterials as biostimulators for the methanogenic bacteria has been commonly deployed. This is to maximize the biogas production from livestock manure through the anaerobic digestion processes. Yet, the environmental impact of the nanomaterials as manure additives has not been evaluated. In this respect, different nanoparticles (NPs) of nickel (Ni), cobalt (Co), iron (Fe) and iron oxide (Fe3O4) were used in biogas production to study their environmental impact using life-cycle assessment (LCA) methodology. Global warming, greenhouse gas (GHG) emissions, acidification, eutrophication, resource depletion, human toxicity potential, and ozone layer depletion potential were investigated. The results showed that Co NPs was the most effective in reducing the greenhouse gas emissions through electricity production. The greenhouse gas emissions were 0.0366, 0.0276, 0.0225, 0.0336 and 0.0290 kg CO2 eq./MJ elect. for the control, Ni NPs, Co NPs, Fe NPs and Fe3O4 NPs, respectively. Furthermore, Co NPs delivered the lowest acidification, human toxicity potential and eutrophication values. While, Ni NPs delivered the lowest resource and ozone layer depletion values.

Abstract Recently, the use of nanomaterials as biostimulators for the methanogenic bacteria has been commonly deployed. This is to maximize the biogas production from livestock manure through the anaerobic digestion processes. Yet, the environmental impact of the nanomaterials as manure additives has not been evaluated. In this respect, different nanoparticles (NPs) of nickel (Ni), cobalt (Co), iron (Fe) and iron oxide (Fe3O4) were used in biogas production to study their environmental impact using life-cycle assessment (LCA) methodology. Global warming, greenhouse gas (GHG) emissions, acidification, eutrophication, resource depletion, human toxicity potential, and ozone layer depletion potential were investigated. The results showed that Co NPs was the most effective in reducing the greenhouse gas emissions through electricity production. The greenhouse gas emissions were 0.0366, 0.0276, 0.0225, 0.0336 and 0.0290 kg CO2 eq./MJ elect. for the control, Ni NPs, Co NPs, Fe NPs and Fe3O4 NPs, respectively. Furthermore, Co NPs delivered the lowest acidification, human toxicity potential and eutrophication values. While, Ni NPs delivered the lowest resource and ozone layer depletion values.

AbstractMicroalgae have the potential to become the primary source of biodiesel, catering to a wide range of essential applications such as transportation. This would allow for a significant reduction in dependence on conventional petroleum diesel. This study investigates the effect of biostimulation techniques utilizing nanoparticles of Magnesium oxide MgO, Calcium hydroxyapatite Ca10(PO4)6(OH)2, and Zinc oxide ZnO to enhance the biodiesel production of Chlorella sorokiniana. By enhancing cell activity, these nanoparticles have demonstrated the ability to improve oil production and subsequently increase biodiesel production. Experimentally, each nanomaterial was introduced at a concentration of 15 mg L−1. The results have shown that MgO nanoparticles yielded the highest biodiesel production, with a recorded yield of 61.5 mg L−1. Hydroxyapatite nanoparticles, on the other hand, facilitated lipid accumulation. ZnO nanoparticles showcased a multifaceted advantage by enhancing both growth and lipid content. Thus, it is suggested that these nanoparticles can be used effectively to increase the lipid content of microalgae. These findings highlight the potential of biostimulation strategies utilizing MgO, hydroxyapatite, and zinc oxide nanoparticles to bolster biodiesel production.

AbstractMicroalgae have the potential to become the primary source of biodiesel, catering to a wide range of essential applications such as transportation. This would allow for a significant reduction in dependence on conventional petroleum diesel. This study investigates the effect of biostimulation techniques utilizing nanoparticles of Magnesium oxide MgO, Calcium hydroxyapatite Ca10(PO4)6(OH)2, and Zinc oxide ZnO to enhance the biodiesel production of Chlorella sorokiniana. By enhancing cell activity, these nanoparticles have demonstrated the ability to improve oil production and subsequently increase biodiesel production. Experimentally, each nanomaterial was introduced at a concentration of 15 mg L−1. The results have shown that MgO nanoparticles yielded the highest biodiesel production, with a recorded yield of 61.5 mg L−1. Hydroxyapatite nanoparticles, on the other hand, facilitated lipid accumulation. ZnO nanoparticles showcased a multifaceted advantage by enhancing both growth and lipid content. Thus, it is suggested that these nanoparticles can be used effectively to increase the lipid content of microalgae. These findings highlight the potential of biostimulation strategies utilizing MgO, hydroxyapatite, and zinc oxide nanoparticles to bolster biodiesel production.

Abstract The objective of this study is to increase biohydrogen production from biomass using laser photoactivated nanomaterials. Light saturation of photo-fermentation is a vital factor that influences fermentation effectiveness and hydrogen yield. In this study, it is hypothesized that the bio-stimulation of hydrogen-producing purple non-sulfur (PNS) bacteria using laser photoactivated nanomaterials can enhance the endurance ability of such bacteria to unsteady light irradiation, where this leads to overcome the challenge of light saturation. Furthermore, the addition of nanomaterials leads to bio-stimulate the bacterial cells and enhance their activity and growth rate and, therefore, increase biohydrogen production from biomass. A biohydrogen production system and a model of photobioreactor were manufactured and installed. Food wastes were collected from kitchen leftovers of different fast-food suppliers and were used in this study as feedstocks for biohydrogen production. The production process was conducted as following: exposing 16.5 mg/l of graphitic carbon nitride nanosheets on the one hand and 50 mg/l of nickel nanoparticles on the other hand to a helium-neon green laser radiation source with a wavelength of 543 nm for 1 h, then adding them to the bacterial inoculum and then mixing them with biomass and water by a ratio of 0.5:1:2 which were then kept in the photobioreactor exposed to white light emitting diodes (LEDs) with a luminous flux of 3600 lumen and at 30 °C for 26 days with mixing for 5 min every 30 min to produce biohydrogen. By this method, it is possible to improve the bioenvironmental conditions and the bio-responses of bacteria which results in increasing the biohydrogen yield by 287% over the conventional method.

Abstract The objective of this study is to increase biohydrogen production from biomass using laser photoactivated nanomaterials. Light saturation of photo-fermentation is a vital factor that influences fermentation effectiveness and hydrogen yield. In this study, it is hypothesized that the bio-stimulation of hydrogen-producing purple non-sulfur (PNS) bacteria using laser photoactivated nanomaterials can enhance the endurance ability of such bacteria to unsteady light irradiation, where this leads to overcome the challenge of light saturation. Furthermore, the addition of nanomaterials leads to bio-stimulate the bacterial cells and enhance their activity and growth rate and, therefore, increase biohydrogen production from biomass. A biohydrogen production system and a model of photobioreactor were manufactured and installed. Food wastes were collected from kitchen leftovers of different fast-food suppliers and were used in this study as feedstocks for biohydrogen production. The production process was conducted as following: exposing 16.5 mg/l of graphitic carbon nitride nanosheets on the one hand and 50 mg/l of nickel nanoparticles on the other hand to a helium-neon green laser radiation source with a wavelength of 543 nm for 1 h, then adding them to the bacterial inoculum and then mixing them with biomass and water by a ratio of 0.5:1:2 which were then kept in the photobioreactor exposed to white light emitting diodes (LEDs) with a luminous flux of 3600 lumen and at 30 °C for 26 days with mixing for 5 min every 30 min to produce biohydrogen. By this method, it is possible to improve the bioenvironmental conditions and the bio-responses of bacteria which results in increasing the biohydrogen yield by 287% over the conventional method.