ABSTRACT Objective: To analyze the prevalence and factors associated with the lifestyle profile of public basic education teachers in Minas Gerais during the COVID-19 pandemic. Method: Epidemiological websurvey carried out with public basic education teachers in Minas Gerais. Data collection took place from August to September2020 via digital form. Anthropometric, sociodemographic, work, and lifestyle characteristics were evaluated. Poisson Regression was used. Results: 15,641 teachers participated and 31.1% had inadequate health habits. There was a higher prevalence among men (PR=1.38; 95%CI:1.31;1.45), older age (PR=1.20; 95%CI: 1.07;1.34), greater weekly workload (RP=1.10; 95%CI:1.03;1.17) and those dissatisfied with work (RP=1.21; 95%CI:1.15;1.27). As a protective factor, professors with longer teaching experience (RP=0.92; 95%CI:0.87;0.98) and those hired or appointed (PR=0.89; 95%CI:0.85) ;0.94). Conclusion: Lifestyle inadequacy was found among older male teachers, with longer working hours and job dissatisfaction.

RESUMEN Objetivo: Analizar la prevalencia y los factores asociados al perfil de estilo de vida de los docentes de educación básica pública de Minas Gerais durante la pandemia de COVID-19. Método: Encuesta epidemiológica de tipo websurvey realizada con profesores de educación básica pública en Minas Gerais. La recolección de datos ocurrió de agosto a septiembre2020 a través de formulario digital. Se evaluaron características antropométricas, sociodemográficas, laborales y de estilo de vida. Se utilizó la Regresión de Poisson. Resultados: Participaron 15.641 docentes y el 31,1% presentaba hábitos de salud inadecuados. Hubo mayor prevalencia en hombres (RP=1,38; IC 95%: 1,31; 1,45), mayor edad (RP=1,20; IC 95%: 1,07; 1,34), mayor carga de trabajo semanal (RP=1,10; IC 95%: 1,03). ;1,17) y los insatisfechos con el trabajo (RP=1,21; IC95%:1,15;1,27). Como factor protector, profesores con mayor experiencia docente (RP=0,92; IC95%:0,87;0,98) y contratados o nombrados (RP=0,89; IC95%:0,85;0,94). Conclusión: Se encontró inadecuación en el estilo de vida entre los maestros hombres y mayores, con jornadas laborales más largas e insatisfacción laboral.

RESUMO Objetivo: Analisar a prevalência e fatores associados ao perfil do estilo de vida dos professores da educação básica pública de Minas Gerais na pandemia da COVID-19. Método: Inquérito epidemiológico websurvey realizado com professores da educação básica pública de Minas Gerais. A coleta de dados ocorreu de agosto a setembro/2020 via formulário digital. Foram avaliadas as características antropométricas, sociodemográficas, laborais e estilo de vida. Utilizou-se a Regressão de Poisson. Resultados: Participaram 15.641 professores e 31,1% apresentaram hábitos inadequados de saúde. Houve maior prevalência entre homens (RP=1,38; IC95%:1,31;1,45), maior idade (RP=1,20; IC95%: 1,07;1,34), maior carga semanal de trabalho (RP=1,10; IC95%:1,03;1,17) e os insatisfeitos com o trabalho (RP=1,21; IC95%:1,15;1,27). Como fator de proteção encontraram-se os professores com mais tempo de trabalho docente (RP=0,92; IC95%:0,87;0,98) e contratados ou designados (RP=0,89; IC95%:0,85;0,94). Conclusão: Verificou-se inadequação do estilo de vida entre os professores homens mais velhos, com maior jornada laboral e insatisfação com o trabalho.

Phytochemical study of the roots of Euphorbia phosphorea Mart. (Euphorbiaceae) was carried out through chromatographic techniques, resulting in the isolation of a new ent-abietane diterpene named 11β,12β-dihydroxy-ent-abieta-8(14),13(15)-dien-16,12α-olide (1), and of nine known ent-abietane diterpenes jolkinolide A (2), jolkinolide E (3), euphorin H (4), euphopilolide (5) jolkinolide F (6), ent-12-hydroxy-12[R]-abieta-8(14),13(15)-dien-16,12-olide (7), ent-11α-hydroxyabieta-8(14),13(15)-dien-16,12α-olide (8), 17-hydroxyjolkinolide B (9) and caudicifolin (10). The structures of all compounds were established using spectroscopic techniques such as 1D and 2D NMR, and the structure of the compound 1 was established also with MS, IR and ECD. All compounds were submitted to an in silico study through of a predictive model and then submitted to in vitro tests against Mycobacterium tuberculosis and M. smegmatis for evaluation of their antimycobacterial activity. Compounds 5 and 9 showed mycobacterial growth inhibition with MIC values of 62.5 μM against M. tuberculosis and M. smegmatis, respectively.

Abstract Currently, protected areas around the world have a demand for volunteer work. At the same time, people in several countries that house protected areas seek out these spaces to serve as volunteers. This process occurs in a scenario strongly influenced by the neoliberal economy, which is marked by cuts in environmental management budgets and increased protected areas visitation. Based on this context, the objective was to analyze the role of volunteer work in protected areas in the context of neoliberal paradigm predominance. For this purpose, it was established a current overview of volunteer activity through a case study in Brazil by collecting information from volunteers and managers, heads or managers of protected areas receptive to volunteer work in interviews using structured questionnaires. It was found that Parques Nacionais are the categories with the greatest demand for volunteer work. It was also found the most part of volunteers is between 20 and 30 years old, and their education level is higher education in undergraduate courses related to biological sciences. It was identified significant differences between the perceptions of managers and volunteers about volunteer work objectives. However, both groups indicated that “Environmental education/environmental interaction and interpretation” and “Support for visitation” are the most frequently performed activities, and the main form of support and trade-off for volunteer work is the offering of certificates. Thus, volunteer work seeks to contribute to the protected areas objectives by supporting the management of these areas during public use activities. However, in the current scenario, this work is palliative in the face of the impacts of the dismantling of environmental policy that affects most countries that have Protected areas and have surrendered to neoliberal conservation.

This study compares the techniques cold vapour atomic fluorescence spectrometry (CV-AFS) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of Hg in biological samples (hepatic tissue from marine tetrapods). Acid digestions were performed for the samples and aliquots of them were analysed by ICP-MS and CV-AFS. To minimize the Hg memory effect in its determination by ICP-MS, gold (200 µg L-1 in 5% v v-1 HCl) was added to the sample digests. The detection limits were 0.02 mg kg-1 for ICP-MS and 0.01 mg kg-1 for CV-AFS. Accuracy was assessed by the calculation of the recovery obtained from TORT-3 (lobster hepatopancreas) certified reference material analysis. Accurate results were obtained for both CV-AFS and ICP-MS. The comparison of the results obtained for hepatic tissue with and without lyophilization showed a significant difference among them (at 95% of confidence level), evidencing losses of Hg in the lyophilization process.

ABSTRACT Objective: Staphylococcus aureus infections remain associated with considerable morbidity and mortality in both hospitals and the community. There is little information regarding the role of ovarian hormones in infections caused by S. aureus. The aim of this study was to evaluate the effects of ovariectomy in the immune response induced by S. aureus. Methods: Female mice BALB/c were ovariectomized (OVX) to significantly reduce the level of ovarian hormones. We also used sham-operated animals. The mice were inoculated intraperitoneally with S. aureus. Blood samples were collected for leukocyte count and bacterial quantification. The uterus and spleen were removed and weighed to calculate the uterine and splenic indexes. Lungs were removed and fractionated for immunohistochemical analysis for macrophage detection (anti-CD68) and relative gene expression of IL-6, IL-1β and TNF-α by RT-PCR. Results: Ovariectomy enlarged spleen size and generally increased circulating lymphocytes. OVX females experienced a continuation of the initial reduction of lymphocytes and a monocyte and neutrophil late response compared to shams (p ≥ 0.05). Moreover, OVX females showed neutropenia after 168 h of infection (p ≥ 0.05). Macrophage response in the lungs were less pronounced in OVX females in the initial hours of infection (p ≥ 0.01). OVX females showed a higher relative gene expression of IL-1β, IL-6 and TNF-α in the lung at the beginning of the infection compared to sham females (p ≥ 0.01). Among the uninfected females, the OVX control females showed a higher expression of IL-6 in the lung compared to the sham control females (p ≥ 0.05). In this model, the lack of ovarian hormones caused a minor increase in circulating leukocytes during the initial stage of infection by S. aureus and increased pulmonary gene expression of IL-1β, IL-6, and TNF-α. Ovariectomy alone enlarged the spleen and increased circulating lymphocytes. Ovarian hormones acted as immunoprotectors against S. aureus infection.

RESUMO Objetivo: Relatar o plano de análise estatística (primeira versão) para o estudo Balanced Solutions versus Saline in Intensive Care Study (BaSICS). Métodos: O estudo BaSICS é um ensaio multicêntrico fatorial e randomizado que avaliará os efeitos da administração dos fluidos Plasma-Lyte 148 em comparação com solução salina 0,9% como fluido de escolha em pacientes críticos, assim como os efeitos de uma velocidade de infusão lenta (333mL/hora) em comparação com uma velocidade de infusão rápida (999mL/hora) durante desafios com volume, em importantes desfechos do paciente. O tipo de fluido será mantido cego para os investigadores, pacientes e nas análises. Não será possível, entretanto, ocultar dos investigadores a velocidade de infusão, mas os procedimentos de análise serão mantidos cegos quanto a esse aspecto. Resultados: O estudo BaSICS terá como parâmetro primário a mortalidade em 90 dias, que será testada com utilização de modelos de risco proporcional de Cox de efeitos mistos, considerando os centros de estudo como variável randômica (modelos de fragilidade) ajustada por idade, disfunção de órgãos e tipo de admissão. Os parâmetros secundários importantes incluem terapia de substituição renal até 90 dias, insuficiência renal aguda, disfunção de órgãos nos dias 3 e 7 e dias sem ventilação mecânica em 28 dias. Conclusão: Este artigo fornece detalhes referentes à primeira versão do plano de análise estatística para o estudo BaSICS e orientará a análise do estudo após a conclusão do seguimento.

Abstract Objective: To report the statistical analysis plan (first version) for the Balanced Solutions versus Saline in Intensive Care Study (BaSICS). Methods: BaSICS is a multicenter factorial randomized controlled trial that will assess the effects of Plasma-Lyte 148 versus 0.9% saline as the fluid of choice in critically ill patients, as well as the effects of a slow (333mL/h) versus rapid (999mL/h) infusion speed during fluid challenges, on important patient outcomes. The fluid type will be blinded for investigators, patients and the analyses. No blinding will be possible for the infusion speed for the investigators, but all analyses will be kept blinded during the analysis procedure. Results: BaSICS will have 90-day mortality as its primary endpoint, which will be tested using mixed-effects Cox proportional hazard models, considering sites as a random variable (frailty models) adjusted for age, organ dysfunction and admission type. Important secondary endpoints include renal replacement therapy up to 90 days, acute renal failure, organ dysfunction at days 3 and 7, and mechanical ventilation-free days within 28 days. Conclusion: This manuscript provides details on the first version of the statistical analysis plan for the BaSICS trial and will guide the study’s analysis when follow-up is finished.

Resumo Objetivo: Conhecer o perfil epidemiológico dos pacientes portadores da doença inflamatória intestinal no estado do Tocantins. Metodologia: Trata-se de estudo descritivo de dados secundários obtidos a partir do Sistema de Internações Hospitalares do Sistema Único de Saúde, que se compreendem entre Janeiro de 2010 e Dezembro de 2017. Os dados de interesse foram aqueles relacionados ao número total de internações, à faixa etária, sexo, raça, município de internação dos pacientes e caráter dos atendimentos. Resultados: Houve 340 internações hospitalares em razão das doenças inflamatórias intestinais em Tocantins, das quais 204 (60%) foram pacientes femininos e 136 (40%) pacientes masculinos, e a faixa etária predominante foi entre 20 e 59 anos (65,88%). Essas internações duraram em média 4,7 dias e 98,23% delas ocorreram com caráter de urgência. Conclusão: O estudo demonstrou que o perfil epidemiológico da doença inflamatória intestinal no Tocantins constitui-se por pacientes femininos, tendo de 20 a 59 anos, internações de 4,7 dias e predominantemente de urgência, o que torna necessário a implantação de medidas de rastreio de forma a tornar o diagnóstico mais precoce, prevenindo, então, possíveis complicações.

Abstract Objective: This study's objective was to understand the epidemiologic profile of the patients with inflammatory bowel disease in the state of Tocantins, Brazil. Methods: This is a descriptive study of secondary data, which was gathered by using the Informatics Department of the Brazilian Health System, and it corresponds to the cases registered from January of 2010 to December of 2017. The data of interest were those related to the total number of admissions, age range, gender, ethnicity, city of hospitalization, and type of care. Results: There were 340 hospital admissions due to inflammatory bowel diseases in Tocantins, of which 204 (60%) were female patients and 136 (40%), male patients; the predominant age group was between 20 and 59 years old (65.88%). These hospitalizations lasted an average of 4.7 days and 98.23% of them occurred as a matter of urgency. Conclusion: The study demonstrated that the epidemiological profile of the inflammatory bowel disease in the state of Tocantins consists of female patients, aged between 20 and 59 years, with hospitalizations lasting 4.7 days and mainly urgent, demonstrating that it is necessary to implement screening measures in order to make the diagnosis earlier, thus preventing possible complications.

ABSTRACT We aimed to evaluate the effects of crude glycerine purity and levels of glycerol on the fermentative profile, microorganisms counting, and nutritional value of Piatã grass silage. The experiment was carried out in a 3×3+1 completely randomized factorial design using three different types of crude glycerine [low purity (40% of glycerol), medium purity (60% glycerol), and high purity (80% glycerol)], three doses of glycerol (20, 40, and 60 g/kg DM), and a control (no crude glycerine added) as an additional treatment, which were stored for 80 days. Statistical differences were not observed on fermentative losses of the treatments tested. The increase of glycerol doses resulted in higher levels of non-fibrous carbohydrates and lower levels of fibre components. The addition of low-purity crude glycerine increased the levels of fat and in vitro digestibility of silages. The highest levels of lactic acid and acetic acid occurred in the treatments with 60 g/kg of glycerol when using crude glycerine with a low purity. The lowest lactic acid content was observed in the control treatment and in the lowest dose of glycerol. The highest glycerol dose (60 g/kg), associated with the lowest degree of crude glycerine purity (40%) resulted in the greatest nutritional value and provided the best silage conservation.

RESUMO: A co-digestão anaeróbia dos resíduos é uma alternativa para aumentar a produção de metano (CH4) e melhorar a qualidade do biofertilizante. Este estudo teve como objetivo avaliar a melhor condição de coDA dos dejetos de suínos (DS), acrescidos de batata doce (BD) ou mandioca (M) em diferentes inclusões, em biodigestores semi-contínuos. Inicialmente, utilizando biodigestores batelada, foi realizado ensaio de coDA dos DS com BD ou M, adotando-se as relações C/N iguais a 10/1, 13/1, 17/1, e 22/1. Com base nos resultados elegeu-se a relação C/N de 10/1, como sendo a proporção que apresentou maiores reduções de sólidos voláteis (SV) e produções específicas de biogás. A partir destes resultados, efetivou-se o experimento em biodigestores semi-contínuos, composto por três tratamentos (controle (DS), BD 10/1 e M 10/1) com cinco repetições cada, e tempo de retenção hidráulica (TRH) de 30 dias. Foram mensuradas as reduções de sólidos totais (ST) e sólidos voláteis (SV), produções de biogás e CH4, alcalinidade e acidez volátil. O tratamento controle diferiu dos demais e apresentou menor desempenho no rendimento de biogás (752 LN.kgSVadic -1), CH4 (449 LN.kgSVadic -1) e concentração de CH4 (59,7%). Os tratamentos em coDA (BD e M) não diferiram entre si para o rendimento de biogás (901 e 883 LN.kgSVadic -1) e CH4 (590 e 547 LN.kgSVadic -1), no entanto diferiram na concentração de CH4 (65,5 e 61,9%, respectivamente). Os tratamentos apresentaram médias gerais de reduções de 76,1 e 85,9% para ST e SV, respectivamente, não sendo encontrada diferença estatística entre eles. A coDA do DS com BD ou M aumentou a produção e a qualidade do biogás, elevando a concentração de CH4 no mesmo.

ABSTRACT: Anaerobic co-digestion (AcoD) of waste is a method of increasing methane (CH4) yield and improving biofertilizer quality. This study aimed to evaluate the best AcoD conditions for swine manure (SM) with sweet potato (SP) or cassava (C) in different amounts in semi-continuous biodigesters. Initially, using batch biodigesters, an AcoD test of the SM with SP or C was performed, adopting carbon/nitrogen (C/N) ratios of 10/1, 13/1, 17/1, and 22/1. Based on the results, a C/N ratio of 10/1 was chosen, which was the proportion that resulted in the highest reduction of volatile solids (VS) and specific biogas production. From these results, the experiment was carried out in semi-continuous biodigesters, consisting of three treatments (control (SM), SP 10/1, and C 10/1) with five replicates and a hydraulic retention time (HRT) of 30 days. Total solid (TS) and volatile solid (VS) reductions, biogas and CH4 yields, alkalinity, and volatile acidity were measured. The control treatment differed from the others and resulted in decreased biogas yield (752 LN.kgVSadded -1), CH4 (449 LN.kgVSadded -1), and CH4 content (59.7%). The AcoD treatments (SP and C) did not differ significantly for biogas yield (respectively, 901 and 883 LN.kgVSadded -1) and CH4 (respectively, 590 and 547 LN.kgVSadded -1); however, they differed in CH4 content (65.5% and 61.9% respectively). The treatments showed general reduction averages of 76.1% and 85.9% for TS and VS, respectively, with no statistical difference found between them. The AcoD of the SM with SP or C increased the production and quality of the biogas, increasing the concentration of CH4 therein.

Abstract INTRODUCTION: Leishmaniasis is a global public health concern. Currently available treatments are associated with considerable side effects. The use of nanotechnology has shown promise for improving efficacy and bioavailability and minimizing side effects. METHODS: This study investigated available literature, including patents and scientific articles, to identify advances in the use of nanotechnology for the treatment of leishmaniasis. RESULTS: Our findings revealed a stable number of patents and scientific articles published over the past five years. CONCLUSIONS: There is a need to intensify research on the use of nanotechnology for the treatment of leishmaniasis.

RESUMO: O estudo teve como objetivo avaliar o efeito da adição de caldo de cana-de-açúcar sobre a dinâmica da população de Escherichia coli e presença de E. coli shigatogixênicas (STEC) no processo de codigestão anaeróbia de dejetos de bovinos leiteiros. Foram utilizados dez biodigestores bateladas divididos em dois tratamentos, dejeto sem caldo de cana-de-açúcar (DSC) e dejeto com caldo (DCC), com tempo de retenção hidráulica (TRH) de 90 dias. Para o monitoramento periódico da dinâmica da população E. coli e presença de E. coli shigatoxigenicas, do pH e da acidez volátil, realizados a cada dez dias, foram abastecidos mais 36 biodigestores bateladas, construídos de garrafas de material plástico de um litro, sendo 18 unidades para cada tratamento. A redução das populações de E. coli no decorrer do tempo foi significativa no DSC (60 dias) e no DCC (20 dias). A inativação de E. coli shigatoxigênicas ocorreu em um período mais curto, 40 dias no DSC e menos de 10 dias no DCC. Foram obtidas diferenças significativas entre os tratamentos para os valores de pH, que foram menores, e as concentrações de ácidos voláteis, que foram maiores, com adição de caldo e contribuíram para a inativação mais rápida da E. coli e STEC. A dose de caldo de cana-de-açúcar utilizada (7%) sugere a adequada sanitização do dejeto bovino leiteiro, tendo em vista a alta redução na população de E. coli e a inativação de STEC.

ABSTRACT: The objective of this study was to evaluate the effects of the addition of sugarcane juice on the population dynamics of Escherichia coli and the presence of Shiga-toxigenic E. coli (STEC) during the anaerobic codigestion of dairy cattle manure. For the overall analyses at the end of a hydraulic retention time of 90 days, ten two-liter batch-type biodigesters were divided into two treatment groups: biodigester containing manure and water (MW) and the biodigester containing manure, water and sugarcane juice (MSC). For monitoring the population dynamics and presence of microorganisms, pH, and volatile acidity, tests were carried out every ten days, on 36 smaller-scale batch biodigesters made of one-liter plastic bottles (18 for each treatment). The reductions in E. coli population over time were significant in the MW (60 days) and MSC (20 days) biodigesters. Inactivation of STEC occurred in a shorter period (40 days in MW and <10 days in MSC). Significant differences were obtained between the two treatments, with the pH values being lower, the concentrations of volatile acids (VA) being higher, and the inactivation of E. coli and STEC being faster in the biodigester with sugarcane juice added. The amount of sugarcane juice applied (7%) suggests its suitability for the sanitization of dairy cattle manure for use as a biofertilizer, given the high reduction in the E. coli population and inactivation of STEC.

RESUMO: Objetivou-se encontrar a melhor dose de inclusão de óleo residual durante a co-digestão de substratos preparados com dejetos de bovinos leiteiros e suínos, com o intuito de maximizar as reduções de sólidos e as produções de biogás. Foram realizadas no abastecimento e desabastecimento dos biodigestores as análises de sólidos totais (ST), sólidos voláteis (SV) e fibra em detergente neutro (FDN), enquanto as mensurações de biogás duas vezes por semana. A máxima redução de SV (51,4%) foi possibilitada pela inclusão de até 54,6g de óleo de descarte kg dejetos-1, já as máximas degradações de FDN ocorreram com adições de até 69,4g de óleo de descarte kg dejetos-1. As inclusões de até 64g de óleo de descarte kg dejetos-1 possibilitaram produções específicas de biogás de 291,4 e 251,0 L de biogás.kg SV-1 adicionado, para substratos contendo dejetos de suínos e bovinos respectivamente. A adição de óleo em doses entre 45,1 e 69,4g.kg-1 a substratos contendo dejetos de bovinos ou suínos maximiza as reduções dos constituintes sólidos e fibrosos bem como potencializa as produções específicas de biogás, sendo que o dejeto de suíno ainda suporta maiores doses de inclusão de óleo residual.

ABSTRACT: This study aimed to obtain the best dose of waste cooking oil inclusion for the co-digestion of substrates prepared with dairy cattle and swine manure in order to maximize solids reductions and biogas yield. Analyses of total solids (TS), volatile solids (VS), and neutral detergent fiber (NDF) were performed during the loading and unloading of digesters, while biogas yield was measured twice a week. The maximum reduction in VS (51.4%) was reached with the inclusion of up to 54.6g waste cooking oil.kg manure-1. Maximum NDF degradation occurred with inclusions of up to 69.4g waste cooking oil.kg manure-1. Inclusions of up to 64g of waste cooking oil.kg manure-1 provided specific biogas yield of 291.4 and 251.0L biogas.kg VS-1 added to substrates with swine and cattle manure, respectively. Adding oil at doses between 45.1 and 69.4g waste cooking oil kg manure-1 to substrates composed of cattle or swine manure maximizes reductions of solids and fibrous constituents and enhances specific biogas yield. Furthermore, swine manure supports higher doses of waste cooking oil.

ABSTRACT This research aimed to evaluate enzyme supplementation in diets with different nutritional levels for pigs in their feces excretion and anaerobic digestion. Fifty four gilts were placed on diets formulated to achieve 100 or 95 or 90 % of a pig's nutrient requirements, with the addition of an enzyme complex containing amylase, β-glucanase, cellulase, pectinase, xylanase, protease and phytase (diets 100E, 95E and 90E) or without the enzymes (diets 100, 95 and 90). The trial was divided into three periods (1, 1-2 and 1-3) based on the animal weight. The enzyme complex reduced (p < 0.05) excretions per period and per unit of weight gain (residue coefficients) of organic matter (OM) in Period 1, of N, Ca, Zn and Na in Period 1-2, and of Na excretions and residue coefficients in Period 1-3. Animals fed diet 95E had lower excretions (p < 0.05) of dry (DM), organic and mineral matters, N, Ca, Fe, Mn and Cu, and lower residue coefficients (p < 0.05) of DM, OM, P, Fe, Mn and Cu compared with the animals fed diet 95, in Period 1-3. Numerically, the enzyme complex improved biogas and methane production potentials in anaerobic digestion of the feces. The use of an enzyme complex in a diet formulated to provide 95 % of the gilts' nutrient requirements reduced fecal excretion and positively affected the anaerobic digestion of feces. These data show that pig nutrition and feeding are important tools for reducing the potential environmental impact of pig production.

ABSTRACT This research aimed to evaluate the biogas production during the anaerobic biodigestion process of dairy cattle manure, with and without solids separation. Sixteen biodigesters of the batch type were used, each one with 2L of capacity, supplied with manure in four different conditions: (1) pure manure, after washing the floors of the free stall system; (2) manure after the solids separator; (3) manure after the solids separator and sand decanter and (4) manure with the solid retained in separator solids, dissolved in water. The hydraulic retention time was of 196 days. The highest reductions of volatile solids (VS) were obtained for the biodigesters supplied with manure that went through some process of solids separation. The highest potential of methane production(CH4) obtained was of 0.2686 m³ CH4 kg −1 of added VS, supplied to digesters with manure after solids separator. The best potential for biogas and methane production was observed when there was a reduction of the solids concentration in the manure and, in this case, the hydraulic retention time can be reduced, which reduces the volume of the biodigester and the cost of implementation and maintenance, but the highest biogas production occurred in the biodigesters without solids separation.

ABSTRACT This research analyzes the economic and financial feasibility of implementing a biodigester for confinement of beef cattle on a farm located in the State of São Paulo, through the approach of discounted cash flow. The anaerobic digestion technology arouses interest, due to its advantages with the generation of electricity and the pollution reduction of water resources, soil and air, from the biogas and bio-fertilizer production, high value-added products to cattle raising. It was verified that the treatment system of cattle manure with biodigesters generate biogas and fertilizer as revenue, with free cash flows that enable a return on investment in 3.8 years and return an IRR 26.40% and an MIRR of 10.69%; all above than the minimum rate of attractiveness which confirmed the economic and financial viability of the investment.