Agroenergy from Residual Biomass: Energy Perspective

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

Microalgae Cultivation in Photobioreactors Aiming at Biodiesel Production

The search for a renewable source as an alternative to fossil fuels has driven the research on new sources of biomass for biofuels. An alternative source of biomass that has come to prominence is microalgae, photosynthetic micro-organisms capable of capturing atmospheric CO2 and accumulating high levels of lipids in their biomass, making them attractive as a raw material for biodiesel synthesis. Thus, various studies have been conducted in developing different types of photobioreactors for the cultivation of microalgae. Photobioreactors can be divided into two groups: open and closed. Open photobioreactors are more susceptible to contamination and bad weather, reducing biomass productivity. Closed photobioreactors allow greater control against contamination and bad weather and lead to higher rates of biomass production; they are widely used in research to improve new species and processes. Therefore, many configurations of closed photobioreactors have been developed over the years to increase productivity of microalgae biomass

Study of the Application of UV/Fenton (Fe2+ + H2O2) in the Treatment of Dairy Effluent.

O efluente lácteo é o resíduo obtido no beneficiamento do leite e seus derivados, sendo considerado um passivo de alto poder poluidor. Sem o devido tratamento, quando lançado nos rios compromete a sobrevivência da biota como um todo. O objetivo deste trabalho consistiu em avaliar a eficiência e aplicação do processo Foto-Fenton, seguido por um tratamento biológico (lodo ativado), para a redução da carga orgânica do efluente em questão. A caracterização do efluente lácteo in natura e tratado foi realizada empregando-se métodos estabelecidos e otimizados [DQO, COT, DBO5, Nitrogênio (orgânico e amoniacal), Fósforo total, Ferro, e Sólidos (ST, STF, STV), fenol, análise de elementos via absorção atômica]. Por meio de planejamentos estatísticos - Taguchi, Box-Behnken e fatorial completo - foram determinados os melhores experimentos posteriores aos tratamentos fotocatalíticos e biológico, tendo como variável resposta a redução percentual de COT. Após o processo fotocatalítico, a amostra do melhor experimento foi tratada por um processo biológico (Sistema Lodo Ativado SLA), a fim de verificar a eficiência de degradação da matéria orgânica do efluente estudado através do sistema conjugado (POA- SLA). O sistema híbrido que apresentou maior eficiência teve como variáveis do processo de tratamento fotoquímico: pH = 3,5; Temperatura = 30 ºC; reagente Fenton ( 35 g H2O2 + 3,6 g Fe2+ ) e potência de radiação ultravioleta de 28 W, para um tempo de reação de 60 minutos. Para o tratamento biológico por lodo ativado, os melhores níveis das variáveis foram realizados em pH = 8 e concentração de lodo de 3,0 g L-1. Os resultados para o tratamento híbrido apresentou percentuais de reduções para COT = 94 %, DQO = 97 % e DBO = 83 %.The dairy effluent is the residue obtained from the improvement of milk and its derivatives, being considered a high pollutant. Without the due treatment, when thrown in the rivers it puts in risk the survival of the biota as a whole. The objective of this work consisted of evaluating the efficiency and application of the process photo-Fenton followed by a biological (activated sludge) treatment for the reduction of the organic load of the effluent. The characterization of the dairy effluent in natura and treated was accomplished using established methods [COD, TOC, BOD5, Nitrogen (organic and amoniacal), Total Phosphorus, Iron, and Solids (TS, FTS, VTS), phenol, analysis of elements through atomic absorption]. Through statistical designs, Taguchi, Box-Behnken and Full Factorial, the best experiments were determined for the photocatalytic and biological treatments having the reduction of TOC as their response. After the photocatalytic process, the sample of the best experiment was treated by a biological process in order to verify the efficiency of degradation of the organic matter of the effluent studied through the conjugated (AOP - AS) system. The hybrid system that presented larger efficiency had as factors of the photochemical treatment: pH = 3,5, temperature = 30 ºC, Fenton\'s reagent (35g H2O2 + 3,6 g Fe2+) and potency of ultraviolet radiation of 28 W, for 60 minutes of reaction time. As for the biological treatment, it was accomplished in pH = 8 and concentration of sludge of 3g L-1. Obtained were of the hybrid system the percentage of reductions of TOC = 94 %, COD = 97 % and BOD = 83 %

Otimização do processo de cultivo da microalga Chlorella minutissima como fonte de matéria-prima para a produção de biodiesel

O presente trabalho foi desenvolvido com a microalga Chlorella minutissima com o objetivo de determinar as melhores condições operacionais de fotobioreatores tubulares descontínuos, tipo coluna de bolhas, para o crescimento celular e a produção de lipídeos em função das variáveis de processo: fluxo de CO2 na alimentação, concentração inicial de nitrato, concentração inicial de fosfato, suplementação (metais e vitaminas), temperatura e salinidade. Os experimentos foram planejados utilizando a metodologia de Taguchi. Os resultados obtidos mostraram que a configuração do fotobioreatores tubulares descontínuos, tipo coluna de bolhas, foi adequada para o cultivo da microalga Chlorella minutíssima, apresentando bons resultados de teor de lipídeos, da ordem de 37,08 ± 1,50 % em relação à biomassa seca ao final de 7 dias de cultivo. Definidas as condições ótimas de cultivo foi realizada uma reação como o óleo obtido, empregando catalisador químico (H2SO4). O resultado obtido demonstrou que o catalisador atuou de forma eficiente, convertendo os ácidos graxos em seus respectivos ésteres de etila. Outro fator importante de ressaltar foi a ausência de pigmentos presente no material lipídico, visto que o óleo extraído apresentou coloração amarelada similar aos óleos vegetais tradicionais, como por exemplo, o óleo de soja. Pigmentos quando presentes no material lipídico podem comprometer a conversão dos triglicerídeos em ésteres alquílicos (biodiesel). Chlorella minutissima apresenta vantagens adicionais perante a diversas matérias-primas lipídicas com presença de pigmentos. Para a avaliação da velocidade de crescimento populacional das microalgas foi considerado o modelo cinético de crescimento logístico. A partir desta investigação, verificou-se que o crescimento celular e a produtividade de lipídeos são significativamente dependentes da concentração inicial de nitrato, do fluxo de dióxido de carbono, da concentração de fosfato, da suplementação do meio e da temperatura. Os melhores valores obtidos, tanto para o crescimento quanto para a produtividade de lipídeos, foram para a concentração de nitrato no nível alto e os demais parâmetros significativos no nível baixo. Dessa forma, a metodologia e os resultados apresentados neste trabalho podem ser úteis na busca pela viabilização econômica da produção de biodiesel de microalgas, uma vez que a produção de biodiesel via microalgas ainda é um processo inviável devido aos custos.The current work was developed with the microalgae Chlorella minutissima with the aim of determining the best operational conditions of discontinuous-tubular photobioreactors, bubble-column type, to the cell growth and production of lipids in relation to process variables: CO2 feed flow rate, nitrate initial concentration, phosphate initial concentration, supplements (metals and vitamins), temperature and salinity. The experiments were designed using Taguchi methodology. Results showed that the configuration of discontinuous-tubular photobioreactors, bubble-column type was adequate to the cultivation of microalgae Chlorella minutissima, presenting good results in terms of lipid content, of order of 37.08 ± 1.50% in relation to the dry biomass at the end of the 7 cultivation days. Once optimal cultivation conditions were established, a reaction with obtained oil was carried out using a chemical catalyst (H2SO4). Results showed that the catalyst acted in an efficient way, converting fatty oils in its respective ethyl esters. Another important factor worth noticing was the absence of pigments present in the lipid material, considering that the extracted oil presented a yellow color similar to traditional vegetal oils, such as soy oil. The presence of pigments in the lipid content may compromise the conversion of triglycerides in alkyl esters (biodiesel). Chlorella minutissima presents additional advantage in comparison to diverse lipid raw materials with the presence of pigments. The logistic growth was used as the kinetic model to evaluate the growth rate and speed of microalgae. From this analysis, it was possible to verify that cell growth and the productivity of lipids were significantly dependent on the initial concentration of nitrate, carbon dioxide flow rate, concentration of phosphate, supplementation of media and temperature. Best values obtained for growth as well as for lipid productivity were nitrate concentration in the high level and the other parameters were significant in the low level. Thus, the methodology and results presented in this work can be useful in seeking economic feasibility of production of microalgae biodiesel, since the production of biodiesel is currently is not viable due to the high costs associated to it.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Potencial de biorremediação de Chlorella vulgaris (Chlorophyceae) em águas residuais do processamento da mandioca, Capítulo 9

Most cassava processing industry generates a large volume of wastewater effluent with high contaminating load of COD and BOD and cyanide concentration, posing to a serious threat to the environment. A variety of processes has been tested to treat this wastewater effluent, where the effectiveness in reducing the toxicity varies greatly. Microalgae are photosynthetic microorganisms that can rapidly generate biomass from solar energy, CO2 and nutrients in water, namely those present in wastewater effluents. Also, algal biomass and algae-derived compounds are potentially useful in industrial applications, as well as for biodiesel production. Taking this into account, the aim of this work was evaluated the ability of Chlorella vulgaris to growth on cassava-processing effluent and assess the bioremediation potential by evaluating toxicity of effluent. Batch cultures, with C. vulgaris in suspended and in immobilized-cell systems, under different dilutions (20-50%) of cassava effluent were tested. The effectiveness of the process has been assessed by phytotoxicity, in germination trials of Lactuca sativa. Best results were obtained with C. vulgaris in immobilizedsystems and carried out with higher initial cell concentrations. Regarding the phytotoxicity, after biotreatment we can conclude that microalgae can reduce the toxicity of cassava effluent, leading to Germination Increase index (GI) range of 88-100%.info:eu-repo/semantics/publishedVersio

The Role of Quorum Sensing in the Development of Microcystis aeruginosa Blooms: Gene Expression

Microcystis aeruginosa (M. aeruginosa) is the dominant cyanobacterial species causing harmful algal blooms in water bodies worldwide. The blooms release potent toxins and pose severe public health hazards to water bodies, animals, and humans who are in contact with or consume this water. The interaction between M. aeruginosa and heterotrophic bacteria is thought to contribute to the development of the blooms. This study strives to provide a specific answer to whether quorum sensing is also a potential mechanism mediating the interaction of different strains/species and the expression by gene luxS or gene mcyB in M. aeruginosa growth. The luxS gene in M. aeruginosa PCC7806 is associated with quorum sensing and was tested by q-PCR throughout a 30-day growth period. The same was performed for the mcyB gene. Heterotrophic bacteria were collected from local water bodies: Cibolo Creek and Leon Creek in San Antonio, Texas. Results revealed that in algal bloom scenarios, there is a similar concentration of gene luxS that is expressed by the cyanobacteria. Gene mcyB, however, is not directly associated with algal blooms, but it is related to cyanotoxin production. Toxicity levels increased in experiments with multiple algal strains, and the HSL treatment was not effective at reducing microcystin levels