This research was established due to an increase of interest in renewable energy sources and utilisation of various wastes and biomass. Gasification is currently one of the most promising thermal-chemical conversion techniques for recovering energy from waste, and the pyrolytic behaviour of secondary refuse fuel (SRF) briquettes and biomass-derived fuels is the starting point for the process. The purpose of this study was to evaluate the pyrolytic characteristics of SRF briquettes and biomass materials, suggest a kinetic model for simulating the pyrolytic process and obtaining the kinetic parameters, and then predict the yield of volatile products in pyrolysis. Knowledge of the chemical composition, the thermal behaviour and the reactivity of SRF briquettes and their blends with other materials, such as biomass and plastic during pyrolysis is very important for the effective design operation of gasification units. The kinetics of the pyrolysis of simulated SRF briquettes, SRF briquettes and pulverised biomass samples was successfully modelled by a scheme consisting of two independent general order parallel reactions of the main components which were hemicellulose, cellulose, lignin and plastic. The kinetic parameters estimated through the model were comparable with those reported in the literature. In this research, activation energy values varied between 30 – 70 kJ/mol for lignin pyrolysis, 96 – 137 kJ/mol for hemicellulose and cellulose pyrolysis, and about 260 kJ/mol for plastic pyrolysis. Biomass has a very high volatile content. Adding biomass into SRF briquettes could increase the volatile yield. Increasing the plastic content of SRF briquettes could increase the volatile yield, the derivative thermogravimetric (DTG) peak height and the repeatability of pyrolysis. Inorganic component could shift the cellulose pyrolysis to a lower temperature and cause the hemicellulose pyrolysis and the cellulose pyrolysis highly overlapped, but it could have a positive effect by acting as catalysts and lower the activation energy in the pyrolysis of hemicellulose and cellulose. Molasses used as a binder could improve the DTG peak height and restrain the curve shifting effect of inorganic component on the hemicellulose and cellulose pyrolysis, but couldn’t restrain the lignin pyrolysis at low temperatures during the hemicellulose and cellulose pyrolysis. Molasses could restrain the effect of the lignin pyrolysis at high temperatures on the plastic pyrolysis. Mechanical biological treatment (MBT) process could highly improve the volatile yield and improve the DTG peak height of SRF briquettes.

Wastewater treatment is an energy intensive process and sustainable processes/technologies for the treatment of wastewaters need to be considered. One such contender might be the microbial fuel cell (MFC), a subset of bioelectrochemical system (BES) which generates electricity in the process of electrogenic (generating electrons) degradation of soluble organic contaminants present in the water (or wastewater) by electrogens (electron producing bacteria) at the anode in absence of oxygen. Several issues related to the power performance (also somewhat linked to the cost) of MFCs exist causing barriers in the deployment of up-scaled MFC system and the continual research from a multitude of discipline is focusing on overcoming these issues. Implementation of an MFC system for wastewater treatment would require a large array of MFCs to meet the treatment capacity of the wastewater treatment plant. Commissioning and continual operation of such MFCs would require rapid and cost-effective start-up and improvement in their performance. Optimisation of the power performance is addressed through a systems approach in this study, where improvement in the performance is sought through the system design and control strategies applied to the MFCs. The start-up rate of MFCs has been reduced by 45% using maximum power point tracking (MPPT), which is believed to be cost-effective as exogenous energy (such as in the case of poised-potential) is not required for the rapid start-up. The control of MFC power would need to be considered when up-scaled MFC system is realised. The controller implementation benefits from linearised system models. The viability of such piecewise linearisation of the nonlinear MFC system was demonstrated and the data were shown to be reasonably represented by the 1st order process models throughout its operating range. The occurrence of voltage reversal during stack operation of MFCs is a concern in large arrays particularly, and has been shown to be avoidable by adopting the hybrid stack connectivity. Further enhancement of the performance was sought through the detailed design and fluid dynamics modeling to obtain highly mixed anolyte at low input power, using improved helical anodes which increased the MFC performance at all the tested flow rates (1, 3 and 8 mL min-1) compared to previously studied helical anodes. The up-scaling of MFCs by modularisation was demonstrated and it was shown that the use of improved helical anodes can increase the modular length of the MFC without compromising the power performance. Aggregated power produced from the multi-module MFC (containing 5 modules) was 28.05 ± 3.5 mW (19.75 ± 2.47 W m-3) with an PhD Thesis – Hitesh Chandubhai Boghani 2014 V individual MFC power of 5.61 ± 0.7 mW, when fed with 10 mM sodium acetate at 3 mL min-1 flow rate and at 22 ± 3 °C. So, this thesis presents the strategies for improvement in the performance of MFCs for their applications in wastewater treatment and such strategies may also be transferable to their other applications.

The thesis deals with renewable resources, biomass a its possible uses. The work is focused on Miscanthus sinensis. It described characteristics of plants, growing technology, harvesting and possible ways to use it - mainly burning. Attention is also focused on the yield potential of plants. The practical part of the thesis describes experiments with miscanthus at the experimental site in České Budějovice. There are reported experimental results and their evaluation and comparison with the literature.

The theme of this thesis is to assess the current state of biogas business in selected parts of southern Bohemia and the possibilities for its further development. Further processed economy on the example of a selected company and undertake structured interviews with operators of biogas plants. The first research part handles the issue of biomass, biogas, their preparation - what all have to be careful before and during construction, the legislation itsef and its implementation. In the second part analyzes the economics of selected company, which operates the biogas plant. Everything is monitored from the beginning of construction in 2012 until 2016. Each year are evaluated both financially and in terms of input material consumed. The last section is devoted to the questionnaire controlled interview with executives of three companies that operate biogas plant. The questionnaire consists of three parts - before the construction, during the implementation of biogas plants and biogas into the future of business.

The search for technologies for sustainable development which meets the economic and environmental viability, has provided meetings, and conferences among all nations. Clean energy production and environmental preservation are growing issues and promoted these events worldwide. On the world stage of evolution predicts energy supply that is gradually increasing and the share of biofuels (both ethanol and biodiesel) in the energy world, notably: (i) growth in the production of coal to liquid (CTL, English coal to liquid), (ii) increased demand for unconventional transportation technologies (hybrid and flex fuel cars), and (iii) increased capacity and nuclear power generation and accelerated improvements in energy efficiency. Currently, the use of the potential energy contained in organic materials such as agricultural waste, industrial and urban are still below the potential energy that exists in these inputs. Gasification is a thermochemical process for converting biomass into a gas fuel with basic features. This technology allows and the use of combined cycle with integrated gasification (IGCC), ie, the use of gases produced in gasification Otto cycle engines or gas turbine to produce electricity, and the application of the technique of capture and storage carbon (Carbon Capture and Storage, CCS), which gives low emission of sulfur, offers ease of processing multiple inputs and results in different energy products and post-processable. The choice of gasifier must be in accordance with the abundant supplies in the region. The biggest challenges for the advancement of gasification technology are the high cost of technology compared to the current price of a barrel of oil and lack of skilled labor to operate the system. This thesis aimed to assembly and assessment experiences of a pilot plant for gasification, processing inputs pertaining to the region (coal and briquette sugar cane bagasse), as the results achieved and the production of synthesis gas analysis and the production of electricity. / Fundação de Amparo a Pesquisa do Estado de Alagoas / A procura por tecnologias para um desenvolvimento sustentável o qual satisfaça a viabilidade econômica e ambiental, tem proporcionado reuniões, encontros e conferências entre todas as nações. Produção de energia limpa e preservação ambiental são temas crescentes e fomentados nesses eventos em todo mundo. No cenário mundial de evolução da oferta de energia prognostica-se que seja crescente e gradual a participação de biocombustíveis (tanto etanol quanto biodiesel) na matriz energética mundial, destacando: (i) crescimento na produção de carvão para líquido (CTL, do inglês coal to liquid); (ii) aumento na demanda de tecnologias de transporte pouco convencionais (carros flex fuel e híbridos); e, (iii) aumento na capacidade e geração de energia nuclear e melhorias aceleradas em eficiência energética. Atualmente, o aproveitamento do potencial energético contido nos materiais orgânicos, tais como: resíduos agrícolas, industriais e urbanos ainda são aquém do potencial energético existente nesses insumos. A gaseificação é um processo termoquímico de conversão da biomassa em um gás com características basicamente combustíveis. Esta tecnologia permite a utilização do Ciclo Combinado com a Gaseificação Integrada (IGCC), isto é, a utilização dos gases produzidos na gaseificação em motores de Ciclo Otto ou turbina à gás para produção de energia elétrica, além da aplicação da técnica de captura e armazenamento de carbono, (Carbon Capture and Storage-CCS), que proporciona baixa emissão de enxofre, oferece facilidade em processar vários insumos e resulta em diversos produtos energéticos e pós processáveis. A escolha do tipo de gaseificador deve ser de acordo com os insumos abundante da região. Os maiores desafios para o avanço da tecnologia da gaseificação são os altos custos da tecnologia frente ao preço atual do barril de petróleo e a falta de mão de obra especializada para operação do sistema. Esta dissertação teve por objetivo a montagem e a avaliação experimental de uma planta piloto de gaseificação, processando insumos próprios da região (carvão e briquete de bagaço de cana), como resultados alcançaram a produção e análise dos gases de síntese e a produção de energia elétrica.

Due to the consolidation of the capitalist model, technological progress and consequently the excessive consumption of disposable products, has become the great volume of solid waste generated by society, thus creating serious environmental and public health. Beside this problem, the sharp rise in the price of fossil fuels and the possibility of depletion makes it a great demand for alternative energy sources that are renewable, abundant and economically viable. In this context, the use of municipal solid waste as an alternative source of energy emerges as one of the options appropriate for the biogas generated by the decomposition of organic waste is mainly composed by methane (CH4), one of the main greenhouse effect gases trainers and has a high potential energy. This work will focus the exploitation of the urban solid residues as alternative source of energy, mainly in its use as electric energy, identifying your benefits. The main available in the market and used technologies in Brazil for the conversion of the garbage in electric energy will also be identified, characterizing its benefits and impacts that each one can bring to the environment. Moreover, the proposals will be seen that stimulate the use of biogas as renewable energy. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Devido à consolidação do modelo capitalista, dos avanços tecnológicos e consequentemente do excessivo consumo de produtos descartáveis, tornou-se grande o volume de resíduos sólidos gerados pela sociedade, criando assim sérios problemas ambientais e de saúde pública. Ao lado desse problema, a acentuada elevação no preço dos combustíveis fósseis e a possibilidade de seu esgotamento fazem com que seja grande a procura por fontes alternativas de energia, que sejam renováveis, abundantes e economicamente viáveis. Nesse contexto, o aproveitamento dos resíduos sólidos urbanos como fonte alternativa de energia surge como uma das opções adequadas, pois o biogás gerado pela decomposição orgânica do lixo é composto principalmente pelo gás metano (CH4), um dos principais gases formadores do efeito estufa e que possui um elevado potencial energético. Este trabalho enfocará o aproveitamento dos resíduos sólidos urbanos como fonte alternativa de energia, principalmente na sua utilização como energia elétrica, identificando seus principais benefícios. Serão identificadas também as principais tecnologias disponíveis no mercado e utilizadas no Brasil para a conversão do lixo em energia elétrica, caracterizando seus benefícios e impactos que cada uma pode trazer ao meio ambiente. Além disso, serão vistas as propostas que incentivam o uso do biogás como energia renovável.

The increase in energy demand boosted Brazil to seek new sources of energy to meet the growing demand of the country. And the use of planted forests for energy purposes has stood out as a promising alternative, for being a source of generating clean, renewable energy. Eucalyptus forests have been highlighted as the most planted in the world, for being the most productive. However, due to the need for increased productivity's survey was conducted in order to assess the effects of different water conditions on the growth and physiology of eucalyptus clonal seedlings, focusing on the production of biomass for energy generation. This research was developed in the greenhouse, in the laboratory of plant physiology and forest seedlings, in the center of Agrarian Sciences (ECSC) in the Universidade Federal de Alagoas (UFAL), between the months of July to November 2015, with 120-day trial period. Eucalyptus clonal seedlings were used. The seedlings have undergone a process of transplanting, which were cultivated for a period of 60 days for acclimatization. The experimental design was completely randomized design (DIC), the treatments were arranged in factorial 3 x 2 system consisting of three clonal seedlings (144, 1407 and u 865) and two water conditions 75% of field capacity and 100% of field capacity, with five repetitions. To accompany the growth were measured weekly variables (height, number of leaves and stem diameter of clonal seedlings). At the end of the experiment evaluated the production and dry matter allocation of parts areas and roots and root/shoot ratio. Also at the end of the experiment was evaluated the issue of chlorophyll a fluorescence, at noon (Fv/Fm and Yield) and the chlorophyll content in third leaf fully developed, using the portable light modulated Fluorômetro ... and SPAD and by biochemical method. The data were subjected to analysis of variance using the software Assistat, averages were compared with each other by Tukey test at 5% probability. It can be observed that the water condition 100% of field capacity occurred significant differences for all variables, growth and production and rental of biomass, there was also a reduction of the quantum efficiency of photosystem II,green intensity of leaves(Spad) readings and chlorophyll a, chlorophyll b, total chlorophyll and carotenoid. Showed that the water condition 75% of field capacity clonal seedlings developed better. The data indicates that the clone was i144 which had less tolerance for water condition 100% of field capacity, the clones and 1407 865 were those who had a higher tolerance for water condition 100% of field capacity. / O aumento da demanda energética impulsionou o Brasil a buscar novas fontes de energia, para suprir a crescente demanda do país. E a utilização de florestas plantadas para fins energéticos tem se destacado como uma alternativa promissora, por ser uma fonte geradora de energia limpa e renovável. As florestas de eucalipto têm sido evidenciadas como a mais plantada no mundo, por ser a mais produtiva. No entanto, em razão da necessidade do aumento da produtividade está pesquisa foi realizada objetivando avaliar os efeitos das diferentes condições hídricas no crescimento e na fisiologia das mudas clonais de eucalipto, tendo como foco a produção de biomassa para geração de energia. Esta pesquisa foi desenvolvida em casa de vegetação, no Laboratório de Fisiologia Vegetal e no setor de mudas florestais, no Centro de Ciências Agrárias (CECA), pertencente à Universidade Federal de Alagoas (UFAL), entre os meses de julho à novembro de 2015, com período experimental de 120 dias. Foram utilizadas mudas clonais de eucalipto. As mudas passaram por um processo de transplantio, as quais foram cultivadas por um período de 60 dias para aclimatização. O delineamento experimental foi inteiramente casualizado (DIC), os tratamentos foram arranjados no sistema fatorial 3x2 constituído de três mudas clonais (144, 1407 e vc 865) e duas condições hídricas 75% da capacidade de campo e 100% da capacidade de campo, com cinco repetições. Para acompanhar o crescimento foram mensuradas semanalmente as variáveis (altura, número de folhas e diâmetro do caule da mudas clonais). Ao final do experimento avaliou a produção e alocação da matéria seca das partes áreas e raízes e a relação raiz/parte aérea. Também no final do experimento foi avaliado a emissão de fluorescência da clorofila a, ao meio-dia (Fv/Fm e Yield) e o teor de clorofila na terceira folha completamente desenvolvida, utilizando-se o. Fluorômetro portátil de luz modulada e SPAD e pelo método bioquímico. Os dados foram submetidos à análise de variância utilizando o software Assistat, as médias foram comparadas entre si pelo teste de Tukey a 5% de probabilidade. Pode-se observar que na condição hídrica 100% da capacidade de campo ocorreram diferenças significativas para todas as variáveis de crescimento, e para produção e a locação de biomassa, houve também redução da eficiência quântica do fotossistema II, intensidade verde (Spad )e clorofila a, clorofila b, clorofila total e carotenoide. Evidenciou que a condição hídrica 75% da capacidade de campo as mudas clonais desenvolveram-se melhor. Os dados indicam que o clone i144 foi que teve menor tolerância à condição hídrica 100% da capacidade de campo, os clones 1407 e vc 865 foram os que tiveram maior tolerância à condição hídrica 100% da capacidade de campo.

Hydrogen as a clean energy carrier has drawn great attention. Production of H2 from sustainable bio-oil is considered an alternative for conventional fossil fuel based energy system, since the overall process of bio-oil converting to H2 ideally is carbon-neutral and hence environmental friendly. This study focuses on developing an adequate catalyst for bio-oil steam reforming to produce H2. Ruthenium and/ or nickel based catalysts supported on alumina, ceria-alumina or ceria-silica were synthesized by sol-gel method or incipient wetness impregnation and characterized using BET Surface area analysis, Powder X-Ray diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscopy (SEM). Steam reforming of selected model compounds, n-propanol, glycerol and acetic acid, was investigated in a fixed bed tubular flow reactor over the prepared catalysts at 450 or 500 °C. The effects of support nature, preparation method, catalyst composition and reaction temperature on the steam reforming activity and stability of catalysts were studied. Catalysts showing better performance in terms of reactant conversion and H2 yield were selected for investigating the steam reforming of an acetic acid/glycerol aqueous mixture, consisting of acetic acid and glycerol with a weight ratio of 3/7 similar to a bio-oil generated from fast pyrolysis of cellulose. The steam-to-carbon ratio (S/C) and the flow rate of feed were constant at 4 and 0.1 ml/min, respectively. The effluent gas was monitored by GC/TCD and the evolution of carbon conversion and product gas distribution as a function of time was studied. Among all catalysts investigated, the one with nominal composition A10C10N1Rnc showed the best performance in steam reforming at 500 °C as indicated by higher and more stable H2 yields achieved regardless the reactant used. In order to investigate the sorption-enhanced steam reforming, three CaO-based CO2 absorbents were synthesized: two derived from calcium acetate with or without MgO support, noted as CAM and CA, respectively, and the other MgO-supported one derived from calcium d-gluconate, denoted as CGM. Results from the 15-carbonation/regeneration-cycle test suggested that the MgO-containing absorbent CAM has the highest CaO molar conversion and stable CO2 absorption capacity. Though significantly higher CO2 absorption capacity was shown from absorbent CA in the first one cycle, CA absorbent soon lost most of the CO2 absorption capacity due to severe sintering. In addition, the CO2 absorption capacity of absorbent CGM might be underestimated due to insufficient carbonation time. The A10C10N1Rnc catalyst and the CAM absorbent were applied in the steam reforming of acetic acid/glycerol mixture at 500°C. However, no significant improvement can be observed in the presence of absorbent CAM

With recent emphasis on development of alternatives to fossil fuels, sincere attempts are being made on finding suitable lignocellulosic feedstocks for biochemical conversion to fuels and chemicals. Sweet Sorghum is among the most widely adaptable cereal grasses, with high drought resistance, and ability to grow on low quality soils with low inputs. It is a C4 crop with high photosynthetic efficiency and biomass yield. Since sweet sorghum has many desirable traits, it has been considered as an attractive feedstock. Large scale sweet sorghum juice extraction results in excessive amounts of waste sweet sorghum bagasse (SSB), which is a promising low cost lignocellusic feed stock. The ability of two pretreatment methods namely conventional oven and microwave oven pretreatment for disrupting lignocellulosic structures of sweet sorghum bagasse with lime [Ca(OH)2] and sodium hydroxide [NaOH] was evaluated. The primary goal of this study was to determine optimal alkali pretreatment conditions to obtain higher biomass conversion (TRS yield) while achieving higher lignin reduction for biofuel production. The prime objective was achieved using central composite design (CCD) and optimization of biomass conversion and lignin removal simultaneously for each alkali separately by response surface method (RSM). Quadratic models were used to define the conditions that separately and simultaneously maximize the response variables. The SSB used in this study was composed of cellulose, hemicellulose, and lignin in the percentage of 36.9 + 1.6, 17.8 + 0.6, and 19.5 + 1.1, respectively. The optimal conditions for lime pretreatment in the conventional oven at 100 °C was 1.7 (% w/v) lime concentration (=0.0024 molL-1), 6.0% (w/v) SSB loading, 2.4 hr pretreatment time with predicted yields of 85.6% total biomass conversion and 35.5% lignin reduction. For NaOH pretreatment, 2% (w/v) alkali (=0.005 molL-1), 6.8% SSB loading and 2.3 hr duration was the optimal level with predicted biomass conversion and lignin reduction of 92.9% and 50.0%, respectively. More intensive pretreatment conditions removed higher amount of hemicelluloses and cellulose. Microwave based pretreatments were carried out in a CEM laboratory microwave oven (MARS 6-Xpress Microwave Reactions System, CEM Corporation, Matthews, NC) and with varying alkali concentration(0.3 - 3.7 % w/v) at varying temperatures (106.4 - 173.6 °C), and length of time (6.6 - 23.4 min). The NaOH pretreatment was optimized at 1.8 (% w/v) NaOH, 143 °C, 14 min time with predicted yields of 85.8% total biomass conversion and 78.7% lignin reduction. For lime pretreatment, 3.1% (w/v) lime, 138 °C and 17.5 min duration was the optimal level with predicted biomass conversion and lignin reduction of 79.9% and 61.1%, respectively. Results from this study were further supported by FTIR spectral interpretation and SEM images.

O Pampa é um bioma do tipo savana exclusivo da região Neotropical, situado na porção sul da América do Sul, cobrindo a Argentina, o Uruguai e o Brasil. O clima é quente temperado e úmido, com temperaturas anuais que variam de 0° C no inverno e mais de 24° C no verão. Os grandes distúrbios no Pampa se iniciaram a cerca de 300 anos com a chegada da colonização Europeia na região e o advento da agricultura, silvicultura, manejo sem controle pelo fogo e a criação de gado, leiteiro e de corte. Apesar de contribuir para a falta de heterogeneidade vegetal e perda na diversidade de fauna, a pecuária ainda é extensivamente indicada como manejo sustentável do Pampa. Com pesquisas e trabalhos por vezes mais focados no aumento da produtividade do rebanho que na manutenção da biodiversidade, a conservação do Pampa vem sendo negligenciada. O monitoramento de diferentes metodologias de pastejo, tradicional, em mosaico e exclusão total do gado, se faz necessário para um maior entendimento de como a diversidade de plantas e animais se comportam nestes sistemas. Para isso, são necessários bons modelos ecológicos para testes de hipóteses e diferentes manejos, o que sustenta a utilização de aranhas para estes estudos. Aranhas são rápidas colonizadoras, ótimas dispersoras, predadoras generalistas, além de estarem estritamente relacionadas à estrutura vegetal. Suscetíveis a impactos bióticos e abióticos, aranhas são ótimas medidoras de qualidade ambiental e, sendo de fácil amostragem, podem ser envolvidas em estudos sobre diversidade de espécies e indivíduos. Para tanto, este estudo foi realizado na APA do Ibirapuitã, na Campanha do Rio Grande do Sul, Brasil. Seis parcelas, de um hectare cada, foram distribuídas em pares em três fazendas. Cada par é constituído de uma parcela com pastejo, demarcadas apenas por estacas, onde o gado tem livre acesso, e uma parcela sem pastejo, cercadas desde Agosto de 2012 onde o pastejo do gado foi excluído por completo. A principal expectativa principal é que a abundancia, riqueza, biomassa e composição de aranhas serão diferentes quando áreas com e sem pastejo são comparadas forem comparados. As amostragens foram realizadas com o uso de armadilhas de queda do tipo “Pitfall traps” nas primaveras de 2011, 2012 e 2013, e sazonalmente no outono (maio), inverno (setembro) e primavera (novembro) de 2015 e verão (fevereiro) de 2016 para a captura de aranhas de hábito epígeo. Para análises estatísticas, Testes T, ANOVA e ANOSIM foram realizadas. Linyphiidae e Lycosidae foram as famílias mais abundantes e ricas em todas as coletas realizadas. Os resultados obtidos em 2011, 2012 e 2013 não demonstraram diferença significativa na fauna de aranhas, abundância e riqueza quando áreas com e sem pastejo foram comparadas. Contudo, os resultados apresentaram valores maiores nas áreas com pastejo quando comparando com áreas sem pastejo. Em 2015/2016 a abundância e a riqueza de aranhas também não foram significativamente diferentes nos dados coletados, contudo, os valores brutos também apresentaram maiores abundância e riqueza em áreas com pastejo do que nas sem pastejo. Analisando-se as estações como um todo, juntando áreas com e sem pastejo, o verão foi a estação com mais riqueza geral. Contudo, analisando as áreas com e sem pastejo separadamente, o inverno foi a estação mais rica e abundante em cada uma destas áreas. Apesar dos resultados anteriores, as espécies mais abundantes demonstraram diferença significativa em suas abundancias em cada estação do ano quando áreas com e sem pastejo foram comparados. A biomassa das aranhas não foi significativamente diferente para todos os anos entre áreas com e sem pastejo, com valores maiores em áreas com pastejo. Entretanto, espécies mais abundantes demonstraram diferenças significativas em sua biomassa sazonalmente nos anos de 2015 e 2016, com valores maiores em áreas com pastejo. Áreas com e sem pastejo ainda se mantém similares mesmo após quase quatro anos de exclusão do gado em termos de abundância total de aranhas. Apenas aranhas mais abundantes demonstram diferença entre áreas com e sem pastejo em termos de abundância e biomassa. / Pampa is a savanna-like biome, exclusively of Neotropical region, lying in southern part o South America, covering Argentina, Uruguay and Brazil. The climate is hot temperate and humid, with annual temperatures ranging of 0° C in winter and higher than 24° C in summer. The increase of disturbance at Pampa began around 300 years after Europian colonization and the advent of agriculture, silviculture, uncontrolled fire management and creation of dairy and beef cattle. Even livestock causing loss of vegetal heterogeneity and fauna diversity, it is a widely recommended methodology for sustainable management of Pampa. With studies more focused in forage properties and beef production than diversity maintenance, the Pampa conservation has been neglected. Monitoring different livestock methodologies are necessary to improve knowledge of how diversity of plants and animals change during this impact. Thus, using great ecological models, like spiders, are necessary to test hypotheses and different managements. Spiders are quick settlers, great dispersers, generalist predators and are much correlated with vegetal structure. Susceptible to biotic and abiotic impacts, spiders are great environmental quality meters, being easy to sample and to measure abundance, diversity and richness. This study was conduct at Ibirapuitã River Environmental Federal Protection Area “Área de Proteção Ambiental – APA do Rio Ibirapuitã” in Rio Grande do Sul state, Brazil. Six plots, of one hectare each, were distributed in pars in three farms. Each pair is constituted of a closed plot, a fenced plots since August 2012, with total exclusion of cattle graze; and a opened plot with only poles in the corners to demarcate the place, and cattle have free access for graze. Our main expectative is that abundance, richness, biomass and composition of arenofauna will be different when grazed and ungrazed areas were compared. Ground dwelling spiders were sampled with Pitfall traps in springs of 2011, 2012 and 2013, and seasonally in autumn (May), winter (September) and spring (November) 2015 and summer (February) 2016. Statistical analyses were performed using Stundents’ Test, ANOVA and ANOSIM. Linyphiidae and Lycosidae were the most abundant and richer families. Results of 2011, 2012 and 2013 were no significant different in spider abundance and richness when grazed and ungrazed plots were compared. However, raw data suggest higher values of abundance in grazed areas than ungrazed ones. In 2015/2016 samples, spider abundance and richness were not significant different between grazed and ungrazed areas. Raw data suggest that grazed areas abundance and richness was higher than in ungrazed though. Although summer was the richer season in general, winter was the richer season separately in grazed and ungrazed areas. Despite the previous results, abundance of the most abundant species were significant different between grazed and ungrazed areas in general and in each season. Spider biomass was not significant different in any year when grazed and ungrazed areas were compared. However, biomass of most abundant species were significant different seasonally and in each season in 2015/2016. Grazed and ungrazed areas are still very similar even after almost four years of cattle exclusion in terms of spider abundance and biomass. Only most abundant species demonstrate a significant difference between grazed and ungrazed areas in terms of abundance and biomass, with higher values in grazed plots.