The present work aims to evaluate the potential for bioremediation and CO2 fixation by cultivatin... more The present work aims to evaluate the potential for bioremediation and CO2 fixation by cultivating the microalgae of the genus Chlorella minutissima in cassava wastewater. Experimental work investigated the growth of microalgae in the effluent and determined its growth rate based on different dilutions. Four culture media scenarios were created. The values measured in the laboratory were compared with a mathematical model adjusted based on the kinetic growth. The efficiency of the process was evaluated in terms of the reduction of the organic load, nutrient consumption, and cell count in the initial state (time 0) and complete growth (after the seventh day) using microscopy analysis. After biological treatment, a percentage of reduction of COD (chemical oxygen demand) of around 30%, TS (total solids) 75%, nutrient removal 92%, cyanide near 99%, and average CO2 biofixation 0.19 g L−1 d−1 were observed. The reduction percentages are close to those found in the literature for other cultivation media. It was observed in this study that the biomass productivity and CO2 fixation agree with those obtained in other studies and confirm the efficiency of the very tiny Chlorella microalgae with high photosynthetic capacity.
The search for energy alternatives from renewable and clean sources has been gaining prominence a... more The search for energy alternatives from renewable and clean sources has been gaining prominence at the international level, due to the increased demand for energy and the future depletion of fossil fuels, coupled with the concern with environmental issues. The generation of electricity distributed from the use of biomass can contribute to the conservation of the environment, the diversification of the energy matrix, the national economic development, the generation of jobs in the agro-industry and in the distribution of clean energy, as a sustainable alternative. This chapter aims to present information related to the use of different residual biomass as an energy alternative for Brazil, with a focus on electricity generation, based on a bibliographic survey, where it is highlighted as the best sources of biomass for electricity generation in the country, observing the profitability and viability for logistics and national economy.
The stability of colloidal suspensions of engineered nanoparticles in the environment is of great... more The stability of colloidal suspensions of engineered nanoparticles in the environment is of great interest for the risk assessment and treatment of hazardous materials. The relevance of this study is due to the evidence that engineered nanoparticles have been produced and used in commercial products in large scale, especially ZnO and TiO 2 , which are transported through the environmental components interacting with soil and water, representing the high potential impact on the ecosystems. In this research, we newly investigated the influence of nanoparticles of zinc oxide (NPZnO) on the behavior of nanoparticles of titania (NPTiO 2). The impact of parameters such as pH, zeta potential, ionic strength, electric conductivity, suspended nanoparticles size of the colloidal suspensions containing hazardous nanoparticles on its stability, were studied using experimental and theoretical approaches. Leaching experiments were carried out within a sandy soil column model. It was found that the NPTiO 2 in suspensions enhance the stability of the nanoparticles colloidal suspensions, keeping higher nanoparticles concentrations, while NPZnO promotes rapid aggregation, improving the soil particle collector efficiency with a lower concentration in equilibrium in the colloidal suspension, which can be used for promoting environmental impact attenuation and mitigation.
Most of the agricultural industries generate daily waste, which due to toxicity or quantity deser... more Most of the agricultural industries generate daily waste, which due to toxicity or quantity deserve special attention. The cassava starch produces a significant quantity of residues, which must be rationally used for minimizing the environmental impact of the agricultural activities. The present study aims to enhance the use of this solid residue. We analyzed the cassava bagasse by means of the following techniques: thermogravimetric analysis (TG) and differential scanning calorimeters (DSC). It was addressed the effects of operational conditions (final temperature, heating rate, atmosphere, air flow and size of particles). The cassava bagasse samples collected in a cooperative production facility in Paraty-RJ were characterized using TGA/DSC in order to describe the thermal behavior of these residues. The DOE methodology proposed by Taguchi was used to analyze and cover a broader range of operational parameters. The most influential variables were identified for the process of heat production using DOE technique. These variables provide the best combination for heat flux with residence time of 30 min, air flow of 50 mL min −1 , particle size sieved to 0.42-0.71 mm and heating rate of 25 °C min −1. The main parameters related with the thermal decomposition, effective activation energy and decomposition mechanism were newly determined using thermal techniques analysis methods (TGA/DSC) for the cassava residue.
The present work aims to evaluate the potential for bioremediation and CO2 fixation by cultivatin... more The present work aims to evaluate the potential for bioremediation and CO2 fixation by cultivating the microalgae of the genus Chlorella minutissima in cassava wastewater. Experimental work investigated the growth of microalgae in the effluent and determined its growth rate based on different dilutions. Four culture media scenarios were created. The values measured in the laboratory were compared with a mathematical model adjusted based on the kinetic growth. The efficiency of the process was evaluated in terms of the reduction of the organic load, nutrient consumption, and cell count in the initial state (time 0) and complete growth (after the seventh day) using microscopy analysis. After biological treatment, a percentage of reduction of COD (chemical oxygen demand) of around 30%, TS (total solids) 75%, nutrient removal 92%, cyanide near 99%, and average CO2 biofixation 0.19 g L−1 d−1 were observed. The reduction percentages are close to those found in the literature for other cultivation media. It was observed in this study that the biomass productivity and CO2 fixation agree with those obtained in other studies and confirm the efficiency of the very tiny Chlorella microalgae with high photosynthetic capacity.
The search for energy alternatives from renewable and clean sources has been gaining prominence a... more The search for energy alternatives from renewable and clean sources has been gaining prominence at the international level, due to the increased demand for energy and the future depletion of fossil fuels, coupled with the concern with environmental issues. The generation of electricity distributed from the use of biomass can contribute to the conservation of the environment, the diversification of the energy matrix, the national economic development, the generation of jobs in the agro-industry and in the distribution of clean energy, as a sustainable alternative. This chapter aims to present information related to the use of different residual biomass as an energy alternative for Brazil, with a focus on electricity generation, based on a bibliographic survey, where it is highlighted as the best sources of biomass for electricity generation in the country, observing the profitability and viability for logistics and national economy.
The stability of colloidal suspensions of engineered nanoparticles in the environment is of great... more The stability of colloidal suspensions of engineered nanoparticles in the environment is of great interest for the risk assessment and treatment of hazardous materials. The relevance of this study is due to the evidence that engineered nanoparticles have been produced and used in commercial products in large scale, especially ZnO and TiO 2 , which are transported through the environmental components interacting with soil and water, representing the high potential impact on the ecosystems. In this research, we newly investigated the influence of nanoparticles of zinc oxide (NPZnO) on the behavior of nanoparticles of titania (NPTiO 2). The impact of parameters such as pH, zeta potential, ionic strength, electric conductivity, suspended nanoparticles size of the colloidal suspensions containing hazardous nanoparticles on its stability, were studied using experimental and theoretical approaches. Leaching experiments were carried out within a sandy soil column model. It was found that the NPTiO 2 in suspensions enhance the stability of the nanoparticles colloidal suspensions, keeping higher nanoparticles concentrations, while NPZnO promotes rapid aggregation, improving the soil particle collector efficiency with a lower concentration in equilibrium in the colloidal suspension, which can be used for promoting environmental impact attenuation and mitigation.
Most of the agricultural industries generate daily waste, which due to toxicity or quantity deser... more Most of the agricultural industries generate daily waste, which due to toxicity or quantity deserve special attention. The cassava starch produces a significant quantity of residues, which must be rationally used for minimizing the environmental impact of the agricultural activities. The present study aims to enhance the use of this solid residue. We analyzed the cassava bagasse by means of the following techniques: thermogravimetric analysis (TG) and differential scanning calorimeters (DSC). It was addressed the effects of operational conditions (final temperature, heating rate, atmosphere, air flow and size of particles). The cassava bagasse samples collected in a cooperative production facility in Paraty-RJ were characterized using TGA/DSC in order to describe the thermal behavior of these residues. The DOE methodology proposed by Taguchi was used to analyze and cover a broader range of operational parameters. The most influential variables were identified for the process of heat production using DOE technique. These variables provide the best combination for heat flux with residence time of 30 min, air flow of 50 mL min −1 , particle size sieved to 0.42-0.71 mm and heating rate of 25 °C min −1. The main parameters related with the thermal decomposition, effective activation energy and decomposition mechanism were newly determined using thermal techniques analysis methods (TGA/DSC) for the cassava residue.
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