Environmental Engineering
M. Hazbehiean; N. Mokhtarian; A. Hallajisani
Abstract
More than 5.5 trillion cigarettes are manufactured, and approximately 4.5 trillion cigarette butts are being scattered across the globe per year. These cigarette butts are considered as one of the most hazardous wastes and environmental threats in the world. Thermochemical techniques can be used to turn ...
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More than 5.5 trillion cigarettes are manufactured, and approximately 4.5 trillion cigarette butts are being scattered across the globe per year. These cigarette butts are considered as one of the most hazardous wastes and environmental threats in the world. Thermochemical techniques can be used to turn biomass and solid wastes into valuable final products. Pyrolysis is a comfortable thermochemical technique for turning biomass into biochars, biofuels, briquette solid fuels, and further valuable products such as activated carbons, carbon black, and printing ink. In this study, it was attempted to review the available researches about pyrolysis of cigarette butts with an emphasis on transforming them into carbonated solid and liquid products. It was found that, in addition to the process variables, the type of cigarette butts treatment has a significant effect on the yield and quality of the finished goods. Further studies on the pyrolysis of cigarette butts, especially microwave-assisted pyrolysis and hybrid waste pyrolysis, seemed to be necessary. Solving the technical issues associated with the pyrolysis of cigarette butts to produce the value-added goods would contribute to their application in waste disposal and recycling of other resources. Future studies should focus on the separation methods with the help of gas products to provide the heat required in the reactor. Moreover, mixing the sewage sludge material, as a feed, with cigarette butts and application of appropriate models and experiments to attain the products with specific properties are recommended. The results of this study can be used to eliminate the hazards of the cigarette butts scattered in the environment and create the added value for the pyrolysis process.
Environmental Science
S. Pourkarimi; A. Hallajisani; A. Alizadehdakhel; A. Nouralishahi
Abstract
BACKGROUND AND OBJECTIVES: In this study, the characteristics of bio-oil samples produced through slow pyrolysis of two different macroalgae, i.e. Azolla filiculoides and Ulva fasciata, at optimized conditions were determined and compared.METHODS: For this purpose, the effects of temperature (300-500 ...
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BACKGROUND AND OBJECTIVES: In this study, the characteristics of bio-oil samples produced through slow pyrolysis of two different macroalgae, i.e. Azolla filiculoides and Ulva fasciata, at optimized conditions were determined and compared.METHODS: For this purpose, the effects of temperature (300-500 °C), carrier gas flow rate (0.2-0.8 L/min), and heating rate (10-20 °C/min) on the final bio-oil production were optimized using response surface methodology established by a central composite design.FINDINGS: The highest bio-oil yield from U. fasciata (34.29%) was obtained at the temperature of 500 °C, nitrogen flow rate of 0.2 L/min, and heating rate of 10 °C/min. As for A. filiculoides feedstock, the highest bio-oil yield (30.83%) was achieved at the temperature of 461 °C, nitrogen flow rate of 0.5 L/min, and heating rate of 20 °C/min. Both bio-oil samples contained saturated and unsaturated hydrocarbons. However, the average hydrocarbon chain length was relatively shorter in U. fasciata bio-oil (C4-C16) than in bio-oil from A. filiculoides (C6-C24). Although both bio-oils had almost identical heating values, the U. fasciata bio-oil showed more appropriate properties, i.e. lower viscosity and density. Furthermore, the energy recovery from U. fasciata pyrolysis was calculated as 56.6% which was almost 1.5 times higher than the energy recovery from A. filiculoides pyrolysis.CONCLUSION: The results indicated that U. fasciata bio-oil, with its superior characteristics, could be proposed as a promising candidate for application in diesel-based automotive industries.
Environmental Science
H. Nouri; J. Mohammadi Roushandeh; A. Hallajisani; A. Golzary; S. Daliry
Abstract
BACKGROUND AND OBJECTIVES: Bioenergy is a phenomenon that has attracted humans’ attention for about a century. The desirable biological properties of chlorella sp.microalgae have turned it to one of the most ideal options for the production of biodiesel. However, the economic issues must be taken ...
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BACKGROUND AND OBJECTIVES: Bioenergy is a phenomenon that has attracted humans’ attention for about a century. The desirable biological properties of chlorella sp.microalgae have turned it to one of the most ideal options for the production of biodiesel. However, the economic issues must be taken into account in its industrial scale production. The present study aims to investigate chlorella sp. biomass production and growth conditions by studying the influence of glucose concentration as a carbon source, nitrate concentration as a nitrogen source and pH, as three of the most important factors.METHODS: For this purpose, design of experiment was done by response surface methodology and each factor was investigated simultaneously under glucose concentration in 2-20 g/L, nitrate concentration in 0-1 g/L and 6FINDINGS: The results indicated that carbon concentration has maximum effect on growth and biomass production. The best results were obtained in glucose concentration of 2.6-6 g/L, nitrate concentration of 0.2-0.5 g/L and pH values 7-9. Moreover, the maximum biomass production (1.31 g/L), the highest specific growth rate (0.167 1/day), and the highest biomass productivity (0.085 g/L/Day) were obtained in the following conditions: glucose concentration of 2.6 g/L, nitrate concentration of 0.5 g/L, and pH = 8. The optimal C/N ratio was determined and significant correlation was observed between pH and growth rate change.CONCLUSION: It was concluded that Chlorella sp < /em>., if properly adjusted for both chemical and physical parameters could be a valuable source of biomass for biodiesel production in industrial scale.
S. Daliry; A. Hallajisani; J. Mohammadi Roshandeh; H. Nouri; A. Golzary
Abstract
Due to its abundance and also flexibility of cultivation conditions, Chlorella vulgaris microalgae is one of the most ideal options available in order to production of microalgae based biodiesel. Since vulgaris cultivation for fuel production needs economic considerations to be taken, and in first place ...
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Due to its abundance and also flexibility of cultivation conditions, Chlorella vulgaris microalgae is one of the most ideal options available in order to production of microalgae based biodiesel. Since vulgaris cultivation for fuel production needs economic considerations to be taken, and in first place providing biomass and lipid production costs is important, wide researches have been conducted in this field, and this study aims to spot the best condition for cultivation of this valuable specie by reviewing the whole research conducted. So far, Researchers' efforts show that, the best condition for vulgaris cultivation is mixotrophic regime which is done in a bubble column photobioreactor. Glucose as carbonic source and nitrate as nitrogen source, have the most efficacy among nutrition conditions. It is known the best results obtain in amounts glucose and nitrate of 20 and o.5 g/L respectively. Alkaline medium (pH 9 to 10), non-continuous illumination, 5 to 7 Klux and a 200 mL/min aeration flow rate, indicated the best physical conditions. The most vulgaris biomass amount produced was 3.43 g/L, and the best lipid productivity was measured 66.25 mg/L/day.
