The aim of this thesis is to use differential analysis and finite volume method (FVM) to model and analyze a continuous pulp digester in order to create a detailed picture of the flow behaviour and chemical reactions in the digester. This information will be used to optimize wood chip flow and reactions and to diagnose and avoid faults such as hang-ups and channelling. As digesters increase in size, the importance of control of the liquor flow in the wood chip bed also increases. Pulping reactors are often faced with production disturbances that cause reduced fibre quality, non-uniform chemical reactions and damaging channelling phenomena. The models that are proposed in this thesis aim to consider the fluid dynamics, thermodynamics and chemical reactions together in order to create a model with more detail than has been previously reported. The digester is of the continuous type and has a circular cross-section, with a height of 60 m and a diameter that increases stepwise from 6 m at the top to 7 m at the bottom. The geometry of the digester, including an internal pipe with three different diameters, three inlet flows at three levels of the digester, inlets and outlets at the top and bottom, and a number of peripheral circulation pipes connected to the screens at three levels, is represented in simulations by a 2D axisymmetric model constructed in Gambit. The interactions between the two phases - the wood chips and the alkaline liquor - are studied using the finite volume method (FVM). Eulerian and Mixture numerical methods are evaluated for solving a mass transfer multiphase model with a porous matrix, species transport and reaction system in FLUENT. Variable porosity is used to model channelling in the digester. Comparisons of the results of simulations with real digester data indicate that the multiphase model, with the species transport and mass transfer modules accurately predict the pulping chemical reactions inside the digester and are able to evaluate pulp quality. The species transport model with reaction scheme is able to predict the mass balance equation and stoichiometry of the pulping reaction. The porous media scheme complements this approach to give a more complete view of pulp production, including the effect of faults in the process. The approaches to the FVM described in this thesis enable an accurate view of the pulping process which can contribute to improved control and optimization of the process. / CFD modellering av hydrodynamiska och kemiska reaktioner i massakokare Huvudsyftet med denna avhandling har varit att utveckla en numerisk modell som kan användas för att simulera och styra massatillverkningsprocessen. En finit volym metod har tillämpats, med hjälp av CFD (Computational Fluid Dynamics) programmet FLUENT. Även om den kontinuerliga sulfatprocessen är den dominerande kemiska massaprocessen, så är vår kunskap om vad som händer i kokaren med avseende på hydraulik och de kemiska reaktionerna på en relativt låg nivå. Anledningen är att det är mycket svårt att ta ett prov från vilken punkt som helst i kokaren för att göra olika mätningar. Speciellt, hängningar och kanalbildning i kokaren är inte väl förstådd trots att dessa fenomen orsakar betydande produktions- och kvalitetsförluster. Det finns varken en entydig förklaring till eller lösning för hur man skall kunna undvika hängning och kanalbildningar ännu. Genom CFD-simuleringar som utvecklats i denna avhandling kan vi simulera vad som kan antas hända, och hur dessa fenomen kan upptäckas genom att mäta temperaturer, tryck och Kappatal i olika positioner. CFD-modellerna kan beskriva vad som kan hända i kokaren och indirekt skapa en bild av massaprocessen. Förhoppningsvis kan simuleringarna också användas för att undersöka hur man kan motverka störningarna. Storleken på kokare ökar kontinuerligt för att tillgodose högre produktionstakt men storleksökningen gör det samtidigt ännu svårare att hantera kemiska processer inne i kokaren. Det finns både satsvis- och kontinuerliga kokare, men de modernaste är kontinuerliga kokare. Dessa har ofta komplicerade cirkulationsloopar för att kunna hålla rätt förhållande med avseende på temperatur och kemikaliekoncentrationer i olika delar av kokaren.  Problemen med kokare är bland annat ojämn fördelning av vätskeflödet genom flisen, trycket från flispelaren, fliskomprimering, flisrörelse i olika riktningar, heterogena träflisformer (och storlek på bitarna), tvättningseffektivitet, swing mellan olika vedkvaliteter och hängningar av flis längs väggarna. I denna avhandling har en matematisk 3-D modell utvecklats där alla dessa faktorer och fenomen undersöks för att förbättra kunskapen om flödet och de kemiska processerna som gör det möjligt för oss att hantera och optimera produktionen. Genom att simulera olika driftproblem och jämföra simuleringarna med processdata kan vi försöka analysera kemiska processen inne i kokaren. För att kunna kombinera en verklighetsnära simulering med en rimlig tid för att lösa problemet har en Axisymetrisk 2-D struktur använts. Det betyder att man antar att kokaren ser likadan ut i alla riktningar från centrum och utåt.

Vykdant aplinkosauginius projektus, didėja nuotekų kiekiai išleidžiami į centralizuotus nuotekų tinklus. Didėjant valomų nuotekų kiekiams, didėja ir dumblo kiekiai. Dumblo apdorojimo proceso grandinėje yra labai svarbus dumblo anaerobinis pūdymas. Pūdymas vyksta metantankuose. Efektyvus pūdymas priklauso nuo daugelio veiksnių: temperatūros, maišymo, paduodamo dumblo kiekio ir jo charakteristikų. Vienas iš daugelio, tačiau svarbus veiksnys, darantis poveikį metantankų veikimo efektyvumui, yra maišymas. Atlikus analizę nustatyta, kokios maišymo technologijos naudojamos Lietuvoje ir pasaulyje. Šiuo metu Lietuvoje renkamasi mechaninį maišymą maišyklėmis, su dvejomis mentimis, kurios gali suktis reversu. Atliktas eksperimentas Kauno nuotekų valykloje, nustatyta maišyklės įtaka biodujų susidarymui. Nustatyta kiek iš 1 m3 dumblo susidaro biodujų Utenos, Kauno, Klaipėdos nuotekų valyklose. / Pursuing environmental projects, increasing amounts of sewage waste water are discharged into district networks. With increasing quantities of waste water, quantities of sludge are increasing. Anaerobic sludge digestion is very important in sludge treatment process chain. Efficient digestion depends on many factors: temperature, mixing, flow, characteristics and content of the sludge . One of the many, but an important factor affecting the efficiency of digestion operation is mixing. The analysis of literature has shown what technologies are used in Lithuania and in the world. Curently Lithuanian wastewater treatment plans are choosing mechanical vertical shaft agitators. Agitators are with two blades, and whitch can turn back, for some time. An experiment in Kaunas wastewater treatment plant has shown that mixing can effect biogas production.

This thesis examines how the non-Newtonian characteristics of liquid hog manure affect the flow conditions within a steady-flow anaerobic digester. There are three main parts to this thesis. In the first part of this thesis, the physical properties of liquid hog manure and their variation with temperature and solids concentration are experimentally determined. Naturally¬¬-settled manure sampled from an outdoor storage lagoon is studied, and density, viscosity, and particle size distribution are measured. Hog manure with total solids concentrations of less than 3.6% exhibits Newtonian behaviour; manure between 3.6% and 6.5% total solids is pseudoplastic, and fits the power law; manure with more than 6.5% total solids exhibits non-Newtonian and time-dependent characteristics. The second part of this thesis investigates the flow of Newtonian and non-Newtonian fluids—represented by tap water and xanthan gum solution, respectively—within four lab-scale reactor geometries, using residence time distribution (RTD) experiments. The effect of reactor geometry, flow rate, and fluid viscosity are evaluated. In the third part of this thesis, flow conditions within lab-scale and pilot-scale anaerobic digester reactors are simulated using three-dimensional modeling techniques. The RTDs of lab-scale reactors as predicted by the 3D numerical models compare well to the experimental results. The 3D models are also validated using data from particle image velocimetry (PIV) experiments. Finally, the viscous properties of liquid hog manure at 3% and 8% total solids are incorporated into the models, and the results are evaluated.

This thesis examines how the non-Newtonian characteristics of liquid hog manure affect the flow conditions within a steady-flow anaerobic digester. There are three main parts to this thesis. In the first part of this thesis, the physical properties of liquid hog manure and their variation with temperature and solids concentration are experimentally determined. Naturally¬¬-settled manure sampled from an outdoor storage lagoon is studied, and density, viscosity, and particle size distribution are measured. Hog manure with total solids concentrations of less than 3.6% exhibits Newtonian behaviour; manure between 3.6% and 6.5% total solids is pseudoplastic, and fits the power law; manure with more than 6.5% total solids exhibits non-Newtonian and time-dependent characteristics. The second part of this thesis investigates the flow of Newtonian and non-Newtonian fluids—represented by tap water and xanthan gum solution, respectively—within four lab-scale reactor geometries, using residence time distribution (RTD) experiments. The effect of reactor geometry, flow rate, and fluid viscosity are evaluated. In the third part of this thesis, flow conditions within lab-scale and pilot-scale anaerobic digester reactors are simulated using three-dimensional modeling techniques. The RTDs of lab-scale reactors as predicted by the 3D numerical models compare well to the experimental results. The 3D models are also validated using data from particle image velocimetry (PIV) experiments. Finally, the viscous properties of liquid hog manure at 3% and 8% total solids are incorporated into the models, and the results are evaluated.

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 84-87).

Submitted in fulfillment of the requirements of the degree of Masters of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2018. / The anaerobic process is increasingly becoming a subject for many as it reduces greenhouse gas emissions and recovers carbon dioxide energy as methane. Even though these benefits are attainable, proper control and design of the process variables has to be done in order to optimize the system productivity and improve stability. The aim of this research was to optimize methane and biogas yields on the anaerobic co-digestion of sewage sludge using bio-chemical substrates as co-substrates. The first objective was to find the bio-chemical substrate that will generate the highest biogas and methane yields. The anaerobic digestion of these substrates was operated using 6 L digesters at 37.5℃. The substrate which generated the highest biogas and methane yield in the first batch experiment was then used for the second batch test. The objective was to optimize the anaerobic conditions (substrate to inoculum ratio, co-substrate concentration and temperature) in-order to optimize the biogas and methane yields. The second batch test was achieved using the conventional One-Factor-At-A-Time (OFAT) and the Design of Experiment (DOE) methods. Final analysis showed that the bio-chemical substrates could be substrates of interest to biogas generators. Amongst the substrates tested in the first batch experiment glycerol (Oleo-Chemical Product waste) generated the highest methane and biogas yields of 0.71 and 0.93 L. (g volatile solids added)-1, respectively. It was believed that glycerol contains significant amount of other organic substances such as lipids that have higher energy content than the other bio-chemical substrates, thus generating larger biogas and methane yields. Moreover, digestion of sewage sludge alone produced biogas yields of 0.19 L /g VS and 0.33 L/g COD, and methane yields of 0.16 L/g VS and 0.28 L/g COD. Generally, co-digestion yields were higher than digestion yields of sewage alone. Using the OFAT method the results of the second batch test on glycerol demonstrated highest amounts of volatile solids (VS) reduction, chemical oxygen demand (COD) reduction, biogas yield and methane yield of 99.7%, 100%, 0.94 L (g VS added)-1 and 0.75 L (g VS added)-1 at a temperature, substrate to inoculum ratio and glycerol volume of 50℃, 1 (on VS basis) and 10 mL, respectively. Above 22 mL and substrate to inoculum ratio of 1, the process was inhibited. The DOE results suggested that the highest methane and biogas yields were 0.75 and 0.94 L (g VS added)-1, respectively. These results were similar to the OFAT results, thus the DOE software may be used to define the biogas and methane yields equations for glycerol. In conclusion, anaerobic co-digestion of bio-chemical substrates as co-substrates on sewage sludge was successfully applied to optimize methane and biogas yields. / M

La digestion anaérobie est une succession d’étapes de dégradation de la matière organique, par l’intermédiaire de microorganismes, opérée industriellement dans des digesteurs en béton. Des métabolites microbiens (acides gras volatils (AGV), NH4+, CO2) produits au cours du processus de digestion attaquent la matrice cimentaire du béton. Afin d’assurer un développement pérenne de la filière de méthanisation, il est donc nécessaire de comprendre d’abord tous ces phénomènes d’altération pour ensuite proposer des solutions durables pour les matériaux de construction des digesteurs. Les objectifs de la thèse visaient à identifier et quantifier les agents agressifs pour le béton présents dans les milieux de la méthanisation, puis à comprendre leurs rôles dans les mécanismes d’altération des matrices cimentaires. Enfin, l’action de ces milieux a pu être comparée sur un panel de matériaux cimentaires réalisées à partir de différents liants : ciment Portland ordinaire, ciment de haut-fourneau, ciment d’aluminate de calcium et liant alcali activé. Dans des digesteurs de laboratoire, les concentrations maximales des agents chimiques agressifs mesurées pendant la digestion anaérobie d’un biodéchet modèle étaient de 3000 mg.L-1 d’AGV, de 800 mg.L-1 de NH4+, et de 140 mg.L-1 de CO2 dissous. La prolifération de microorganismes capables de métaboliser ces composés chimiques agressifs a été observée à la surface des matériaux cimentaires exposés dans le biodéchet au cours de sa digestion. La zone dégradée des matériaux cimentaires exposés est partiellement décalcifiée, vraisemblablement du fait de l’action des AGV et de l’ammonium NH4+, et carbonatée en raison de la présence de CO2 dissous. Des essais in situ, c’est à dire en conditions réelles, réalisées sur une plateforme expérimentale de méthanisation, ont permis de confirmer les phénomènes d’altération observés en laboratoire. En termes de durabilité, le ciment alumineux présente la meilleure résistance face aux attaques biochimiques lorsqu’on le compare au ciment ordinaire ou aux ciments composés de laitier de haut-fourneau au sein de systèmes de méthanisation en laboratoire ou in situ. / Anaerobic digestion consists in the degradation of organic matter by the successive actions of microorganisms, industrially operated in digesters made of concrete. Microbial metabolites (volatile fatty acids (VFA), NH4+, CO2) produced during this process attack the cementitious matrix of the concrete. To ensure the development of this new industrial field, it appears essential to understand first the alteration phenomena, then to propose durable solutions for digesters’ construction materials. The thesis’ objectives were first to identify and to quantify the aggressive agents for concrete in anaerobic digestion media, then to understand their impacts on the cementitious materials’ alteration mechanisms. Finally, the impacts of those media were compared on different cement pastes made of : ordinary Portland cement, blast furnace slag cement, calcium aluminate cement or alkali activated materials. During laboratory tests, the maximal concentration in aggressive agents measured during the digestion of a synthetic biowaste were 3 000 mg.L-1 of VFA, 800 mg.L-1 of NH4+, and 140 mg.L-1 of dissolved CO2. The colonization of the microorganisms able to produce the aggressive agents has been observed on the cementitious materials’ surfaces exposed to the biowaste during digestion. The external degraded layers of the exposed cementitious materials are partially decalcified, most likely regarding to the action of the VFA and the NH4+. Carbonation has also been detected caused by the dissolved CO2. In situ experiments, in real conditions, achieved in an experimental anaerobic digestion platform, confirmed the alteration phenomena distinguished in the laboratory tests. In terms of durability, calcium aluminate cement present the best performances against the biochemical attacks compared to ordinary cement or blast furnace slag cement in laboratory or in situ anaerobic digestion systems.

Orientador: Jorge de Lucas Júnior / Banca: Regina Maria Quintão Lana / Banca: João Antonio Galbiatti / Resumo: Objetivou-se avaliar a produção de biogás e a qualidade do biofertilizante, produzidos a partir da associação da cama de frango diluída no biofertilizante obtido com estrume de suíno em diferentes proporções. Esta dissertação está dividida em 3 capítulos: a primeira parte consiste na descrição e apresentação da problemática dos resíduos gerados, objetivo do estudo e descrição do experimento. No Capítulo 2 analisa-se ensaio de biodigestão anaeróbia em sistemas contínuos abastecidos diariamente com dejetos de suínos, por aproximadamente 60 dias, em tempo de retenção hidráulica (TRH) de 30 dias com a finalidade de obtenção de biofertilizante, sendo que este foi armazenado em um tanque aberto, para que estivesse nas mesmas condições encontradas em lagoas, isto é, sujeito aos efeitos dos processos de evaporação e precipitação pluviométrica, sendo este armazenado por aproximadamente 60 dias, conclui-se que o sistema de biodigestão anaeróbia é eficaz para produção de biogás e biofertilizante. O Capitulo 3 consiste no abastecimento de biodigestores batelada, em que o biofertilizante obtido na primeira fase serviu como diluente para a cama de frango. Foram abastecidos doze biodigestores, com três diferentes tratamentos, a saber: cama de frango+biofertilizante+água CF+B+A, a cama de frango+biofertilizante CF+B e a cama+água CF+A, operados com aproximadamente 135 dias de retenção hidráulica. Caracterizaram-se os teores de sólidos totais (ST), sólidos voláteis (SV), análise de macro e micro nutrientes, bem como produção de biogás. Observou-se que o CF+B, foi o que melhor apresentou resultados em relação à produção e composição de biogás e melhores resultados para macro e micronutrientes.No capitulo 4, estão apresentados os dados de adequação de plantéis da avicultura de corte e suinocultura, para a operação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective was to evaluate the production of biogas and the quality of fertilizer, produced from the combination of litter of broiler in diluted fertilizer obtained from pig manure in different proportions. This thesis is divided into 3 sections: the first part is the description and presentation of the problem of waste generated, objective of the study and description of the experiment. In Chapter 2 analyzes the test of anaerobic digestion in continuous systems supplied daily with pig manure, for approximately 60 days with hydraulic retention time (TRH) of 30 days with the purpose of obtaining fertilizer. The fertilizer produced during the whole period was stored in a tank open to the same conditions that were found in ponds, do then subject to the effects of the processes of evaporation and rainfall, which is stored for approximately 60 days, it appears that the system of anaerobic digestion is effective for production of biogas and fertilizer, adding values to swine. Chapter 3 is the supply of digester batch, where the biofertilizante obtained in the first round served as diluent of chicken litter. Were supplied twelve digester, with three different treatments: treatment 1 (biofertilizante+ litter of broiler + water), treatment 2 ( biofertilizante + litter of broiler) and treatment 3 (litter of broiler + water), operated at approximately 160 days of TRH. Were characterized the levels of total solids (TS), volatile solids (VS), analysis of macro and micronutrients, and production of biogas. It was observed that treatment 2, was presented the best results for production and composition of biogas, further reductions of volatile solids, and better results for macro-and micronutrients. Chapter 4 were's present adequacy by stud pigs and fowl, for the operation group digester with waste this activity from the production biogas and fertilizer. / Mestre

Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-17Bitstream added on 2014-06-13T18:57:28Z : No. of bitstreams: 1 costa_lvc_me_jabo.pdf: 349470 bytes, checksum: 39635f401178a561fc5275f262224dec (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Objetivou-se avaliar a produção de biogás e a qualidade do biofertilizante, produzidos a partir da associação da cama de frango diluída no biofertilizante obtido com estrume de suíno em diferentes proporções. Esta dissertação está dividida em 3 capítulos: a primeira parte consiste na descrição e apresentação da problemática dos resíduos gerados, objetivo do estudo e descrição do experimento. No Capítulo 2 analisa-se ensaio de biodigestão anaeróbia em sistemas contínuos abastecidos diariamente com dejetos de suínos, por aproximadamente 60 dias, em tempo de retenção hidráulica (TRH) de 30 dias com a finalidade de obtenção de biofertilizante, sendo que este foi armazenado em um tanque aberto, para que estivesse nas mesmas condições encontradas em lagoas, isto é, sujeito aos efeitos dos processos de evaporação e precipitação pluviométrica, sendo este armazenado por aproximadamente 60 dias, conclui-se que o sistema de biodigestão anaeróbia é eficaz para produção de biogás e biofertilizante. O Capitulo 3 consiste no abastecimento de biodigestores batelada, em que o biofertilizante obtido na primeira fase serviu como diluente para a cama de frango. Foram abastecidos doze biodigestores, com três diferentes tratamentos, a saber: cama de frango+biofertilizante+água CF+B+A, a cama de frango+biofertilizante CF+B e a cama+água CF+A, operados com aproximadamente 135 dias de retenção hidráulica. Caracterizaram-se os teores de sólidos totais (ST), sólidos voláteis (SV), análise de macro e micro nutrientes, bem como produção de biogás. Observou-se que o CF+B, foi o que melhor apresentou resultados em relação à produção e composição de biogás e melhores resultados para macro e micronutrientes.No capitulo 4, estão apresentados os dados de adequação de plantéis da avicultura de corte e suinocultura, para a operação... / The objective was to evaluate the production of biogas and the quality of fertilizer, produced from the combination of litter of broiler in diluted fertilizer obtained from pig manure in different proportions. This thesis is divided into 3 sections: the first part is the description and presentation of the problem of waste generated, objective of the study and description of the experiment. In Chapter 2 analyzes the test of anaerobic digestion in continuous systems supplied daily with pig manure, for approximately 60 days with hydraulic retention time (TRH) of 30 days with the purpose of obtaining fertilizer. The fertilizer produced during the whole period was stored in a tank open to the same conditions that were found in ponds, do then subject to the effects of the processes of evaporation and rainfall, which is stored for approximately 60 days, it appears that the system of anaerobic digestion is effective for production of biogas and fertilizer, adding values to swine. Chapter 3 is the supply of digester batch, where the biofertilizante obtained in the first round served as diluent of chicken litter. Were supplied twelve digester, with three different treatments: treatment 1 (biofertilizante+ litter of broiler + water), treatment 2 ( biofertilizante + litter of broiler) and treatment 3 (litter of broiler + water), operated at approximately 160 days of TRH. Were characterized the levels of total solids (TS), volatile solids (VS), analysis of macro and micronutrients, and production of biogas. It was observed that treatment 2, was presented the best results for production and composition of biogas, further reductions of volatile solids, and better results for macro-and micronutrients. Chapter 4 were’s present adequacy by stud pigs and fowl, for the operation group digester with waste this activity from the production biogas and fertilizer.

Objetivou-se avaliar o uso de nitrato de cálcio (NC) na alimentação de ruminantes com vistas à mitigação da emissão de metano. Foram utilizadas quatro fêmeas de cada subespécie, Bos taurus taurus (Holandês) e vBos taurus indicus (Nelore), com peso médio inicial de 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectivamente, alimentadas com diferentes níveis de nitrato de cálcio na dieta (0%, 1%, 2% e 3%), sendo utilizado delineamento quadrado latino 4X4 replicado. O experimento teve duração de 4 períodos de 28 dias cada. Foram avaliados, a ingestão, excreção e digestibilidade de nutrientes, por meio de marcador externo dióxido de titânio, o comportamento ingestivo, com monitoramento visual por 24 horas, parâmetros sanguíneos, dinâmica ruminal, com esvaziamento total do rumen, contagem de protozoários, fermentação ruminal, pela técnica ex-situ, parâmetros urinários e balanço de nitrogênio, com coleta manual de urina tipo spot, e a biodigestão dos dejetos, por biodigestores do tipo batelada. Os taurinos apresentaram valores superiores para CMS, ingestão e digestibilidade de nutrientes e excreção de MS, PB, FDN, FDA, N, MO e EB, e inferiores para CMS em relação ao PV e PM. Os zebuínos apresentaram maiores taxas de ingestão, ruminação e mastigação de MS e FDN em min/kg, tendo valores inferiores para as mesmas taxas em kg/min. A genética e a dose de nitrato influenciaram as variáveis séricas, porém sem valores fora da normalidade. Quanto à dinâmica ruminal, os taurinos apresentaram valores absolutos superiores, e valores em relação ao PV e PM inferiores. Os zebuínos apresentaram maiores pH médio e mínimo e menos tempo de pH abaixo de 6,2, e maior contagem de protozoários. As concentrações de N-NH3, volume e produção de CH4 foram maiores para os zebuínos. Os taurinos apresentaram valores mais elevados para N microbiano (g/dia) e balanço de N retido (g/kg N ingerido), e menores valores para balanço de N nas fezes (g/kgN ingerido) e N microbiano (mg/kgPM.d-1). O aumento no nível de NC na dieta aumentou a digestibilidade de EE e ENN, tempo médio ruminando e taxa de mastigação de MS e FDN (min/kg), e diminuiu o CMS em relação ao PV e PM e excreção de MS, EE, ENN, MO e EB. A taxa de ingestão de MS e FDN (kg/min), a concentração de creatinina na urina (mg/kgPV), o tempo total comendo e balanço de nitrogênio amoniacal o rúmen sofreram efeito quadrático com a adição de NC na dieta. A porcentagem de FDN, PB e EE nos afluentes dos bidigestores sofreram influência da dose de nitrato na alimentação das vacas. Os biodigestores contendo os dejetos de taurinos tiveram os afluentes com maiores valores de FDN e FDA e menor teor de sólidos totais (ST), com menor volume de biogás e CH4 e menor relação de CH4/quantidade de fezes. Os taurinos apresentaram melhor aproveitamento do alimento, produzindo menos CH4, com menor rendimento verdadeiro de produção de metano nos biodigestores. A adição de NC afetou o consumo, digestibilidade e utilização do nitrogênio porém, sem afetar a produção de CH4 nem a eficiencia dos biodigestores. / The aim of the present study was evaluate the use of calcium nitrate in the feeding of ruminants to mitigate of methane. Four females cattle from each subspecies of cattle, Bos taurus taurus (Holstein) and Bos taurus indicus (Nellore), with initial average weight of 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectively, were used, and they were fed with distinct levels of calcium nitrate in the diet (0%, 1%, 2% e 3%) at four periods of 28 days each. Experimental design was composed by a replicated Latin square 4X4. Were avaluated: ingestion, excretion and digestibility of nutrients, by means of external marker titanium dioxide; the observation of behavior parameters during 24 hours; serum analysis; rumen content collection, aiming assessment of fermentation; protozoa count; ruminal fermentation by the ex-situ technique; manual urine collection for measurement of urinary compounds and nitrogen balance; and the anaerobic digestion of feces using batch digesters. Holsteins presented higher values for the DMI, ingestion and digestibility of the nutrients and excretion of DM, CP, NDF, ADF, N, OM e GE, and lower values for DMI at body weight (BW) and metabolic weight (MW) basis. Nellore cattle showed higher rates of ingestion, rumination and chewing of DM e NDF min/kg, having lower values for the same rates in kg/min. Serum variables were influenced by genetics and nitrate levels, but without values beyond normality. As rumen dynamics, Holsteins presented superior absolute values and inferior values when these parameters were calculated in BW and MW basis. The zebu cattle presented medium and minimum pH larger and less time pH below 6.2, having larger count for protozoa count. Nellore had higher concentrations for NH3, CH4 and production of CH4. Holstein presented higher values for microbial N (g/day) and N retained balance (g/kg N ingested) and lower values for N balance in feces (g/kgN ingested) and microbial N (mg/kgMW.d-1). The increase in the level of CN in the diet increased linearly the digestibility of EE and NNE, average time ruminating, chewing rate for DM and NDF (min/kg), and decreased the DMI in BW and MW basis and the excretion of DM, EE, NNE, OM and GE. The intake rate of DM and NDF kg/min, creatinine in urine (mg/kgBW), the total time eating and NH3 balance showed quadratic effect by increasing the addition of CN in the diet. The levels of nitrate on animal feed influenced the percentage of NDF, CP and EE in the batch digesters afluents. The biodigestors containing the taurine feces presented the highest values of NDF/ ADF affluent and lowest values for total solids (TS), lower volume of biogas and CH4 and lower ratio of CH4/amount of feces. Taurines presented better use of the feed, producing lesser CH4, and lower ultimate methane yield at batch digesters. The CN levels affected the intake, digestibility and nitrogen metabolism, however without affecting the production of CH4 or the batch digester efficiency.