Produção de metano e hidrogênio com hidrolisados gerados no tratamento oxidativo do bagaço de cana-de-açúcar.

Programa de Pós-Graduação em Engenharia Ambiental. Núcleo de Pesquisas e Pós-Graduação em Recursos Hídricos, Pró-Reitoria de Pesquisa e Pós Graduação, Universidade Federal de Ouro Preto.Atualmente, a principal fonte de energia utilizada na grande maioria das atividades industriais é o petróleo e o gás natural, cujas quantidades e disponibilidade estão sujeitas a diferentes fatores como econômicos, ambientais e políticos. Neste sentido, o processamento de recursos renováveis, como a biomassa, é uma alternativa estratégica e sustentável para a produção de energia e combustíveis. Uma fonte de matéria prima renovável (biomassa) para conversão em biocombustível e biogás são os resíduos lignocelulósicos como o bagaço de cana. Tais materiais possuem, em suas composições, teores consideráveis de compostos poliméricos como celulose, hemiceluloses e lignina, os quais podem liberar compostos fermentescíveis para produção de energia mediante o uso de técnicas de pré-tratamento. Em geral os métodos de pré-tratamento de biomassas lignocelulósicas podem ser divididos em físicos, químicos e biológicos e seu objetivo principal é fracionar o material lignocelulósico. No presente estudo, foi avaliada a efetividade de utilização de ozônio, em diferentes valores de pH para permitir a oxidação molecular e radicalar, no pré-tratamento de bagaço de cana-de-açúcar visando à obtenção de hidrolisados fermentescíveis para produção de biogás (CH4 e H2) mediante digestão anaeróbia. As variáveis estudadas no pré-tratamento foram pH, tempo de reação (min), carga de ozônio (mg/min) e razão solido-liquido - RSL (g/mL). Os resultados mostraram que é possível remover 45,2 % da lignina e 48,3 % de hemiceluloses usando ozônio (8 mg/min) em pH 11, por 15 min, na razão RSL de 0,075 g/mL.Os hidrolisados obtidos foram caraterizados em função do teor de açúcares, carbono orgânico total, lignina solúvel, furanos e alguns outros compostos presentes identificados por cromatografia gasosa acoplada à espectrometria de massas. A Avaliação do potencial bioquímico de metano (PBM) e hidrogênio (PBH) dos hidrolisados obtidos, mostrou que é possível produzir 2,6 Nm3 CH4 e 0,2 Nm3 de H2 por kg de COD nas melhores condições. Finalmente, foi realizada uma análise energética dos pré-tratamentos, mostrando um gasto significativamente alto relacionado à produção de ozônio. No entanto, ao se considerar o uso da fração sólida pré-tratada para produção de etanol 2G, o investimento energético no pré-tratamento é compensado, garantindo assim a viabilidade do processo integrado de produção de combustíveis de 1ª e 2ª geração.Currently, the major sources of energy consumed by industrial activities include petroleum and natural gas, whose amounts and availability are both subject to economic, environmental and political factors. With this in mind, the use of renewable resources such as lignocellulosic biomass, serves as an alternative and sustainable strategy for the production of energy and fuels. Sugarcane bagasse can be considered as a good primary source of renewable energy for its conversion into biofuels and biogas. This agroindustrial material is rich in polymeric content such as cellulose, hemicellulose and lignin. After undergoing biomass pretreatments, these polymers may then liberate fermentable sugars for the production of energy. These pretreatments are generally divided into the following groups: physical, chemical and biological, all with the objective of fractionating lignocellulosic material. In the present study, the efficiency of ozone, in differents pH values to assess molecular and radicalar oxidation, was evaluated for the pretreatment of sugarcane bagasse with the objective of obtaining fermentable hydrolysates for the production of biogas (CH4 e H2) via anaerobic digestion. The variables studied included pH, reaction time (min), ozone mass flow (mg/min), and solid-to-liquid ratio - SLR (g/mL). The results show that it is possible to remove 45.2% of lignin and 48.3% of hemicelluloses with the use of ozone (8 mg/min) at pH 11 for 15 min, employing a SLR of 0.075 g/mL . The hydrolysates obtained were characterized by the following contents: sugars, total organic carbon, soluble lignin, furans, and other components identified by gas chromatography and mass spectrometry. The evaluation of biochemical potential of methane (BPM) and hydrogen (BPH) of the resulting hydrolysates show that it was possible to produce 2.6 Nm3 of CH4 and 0.2 Nm3 of H2 per kg of TOC in the best conditions. Lastly, an energetic balance of the pretreatments were made, showing that significantly high energy is needed for ozone production. Therefore, considering the use of the pretreated solid fraction for the production of 2G ethanol, the energetic investment made in the pretreatment is compensed for, guaranteeing the viability of the integrated process for the production of 1G and 2G fuels

Anaerobic-Aerobic combined system for the biological treatment of azo dye solution using residual yeast.

This study aimed to investigate the treatment efficiency of a synthetic dye solution in an anaerobic?aerobic combined reactor system, using pretreated residual yeast as a nutrient source and redox mediator. The applicability of the residual yeast as a nutrient source was firstly evaluated in anaerobic batch tests. Subsequently, two continuous bench?scale treatment settings were studied: (1) an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an activated sludge system and, (2) a UASB reactor followed by a shallow polishing pond. The two system configurations were fed with a synthetic azo dye solution of Yellow Gold Remazol (50 mg/L) and pretreated residual yeast (350 mg/L). According to the results, the UASB/shallow polishing pond?combined reactor attained the best values of chemical oxygen demand (COD) (85%) and dye removal (23%)

Synthesis and application of a new carboxylated cellulose derivative. Part II : removal of Co2+, Cu2+ and Ni2+ from bicomponent spiked aqueous solution.

In the second part of this series of studies, the competitive adsorption of three binary systems Cu2+?Co2+, Cu2+?Ni2+ and Co2+?Ni2+ on a carboxylated cellulose derivative (CTA) was evaluated in binary equimolar (1:1) metal?ion aqueous solutions. Bicomponent adsorption studies were developed as a function of contact time and initial metal ion concentration. Bicomponent adsorption kinetic data was modeled by monocomponent kinetic models of pseudo-first- (PFO) and pseudo-second-order (PSO) and a competitive kinetic model of Corsel. Bicomponent adsorption isotherm data was modeled by the ideal adsorbed solution theory (IAST) and real adsorbed solution theory (RAST) models. The monocomponent isotherm models implemented into the IAST were the Langmuir and Sips models, whereas for the RAST model only the Langmuir model was implemented because this model provided the best prediction of the bicomponent isotherm data. The surface of the CTA adsorbent after bicomponent adsorption of metal ions was also examined by SEM-EDX. The effect of one metal ion on the adsorption capacity of another metal ion was discussed in detail with basis on the kinetic and thermodynamics parameters. The selectivity and performance of the CTA adsorbent for the removal of Cu2+, Co2+ and Ni2+ was also evaluated and discussed

Influence of different thermal pretreatments and inoculum selection on the biomethanation of sugarcane bagasse by solid-state anaerobic digestion : a kinetic analysis.

The present study investigated the potential of UASB inoculum, by itself or mixed to nitrogenous residue (fresh bovine manure ? FBM) or to adapted microorganisms (bovine rumen ? BR), for biomethanation of raw and pretreated sugarcane bagasse (SB) by solid-state anaerobic digestion. The influence of autohydrolysis and organosolv pretreatment conditions on the efficiency of biomethanation process was also evaluated by means of kinetic parameters. Akaike Information Criterion was used to statistically evaluate methane production, and the multi-stage model exhibited the highest fit among the models tested. FBM addition resulted in improvements in the C/N ratio, higher yield (143.3NLCH4 kgVS ?1) and higher rate constant (3.05NLCH4 kgVS ?1day?1) for CH4 production from raw SB without any lag phase when compared to UASB inoculum itself which exhibited 5.6 days of lag phase. The FBM also led to a better inoculum adaptation to substrates which contained inhibitors such as xylooligomers and lignin fragments, and had lower C5 sugar content

Use of anaerobic co-digestion as an alternative to add value to sugarcane biorefinery wastes.

In this study the anaerobic co-digestion (AcD) of sugarcane biorefinery by-products, i.e. hemicelluloses hydrolysate (HH) (obtained by hydrothermal pretreatment of sugarcane bagasse), vinasse, yeast extract (YE) and sugarcane bagasse fly ashes (SBFA), was optimized by means of biochemical methane potential experiments. The best experimental conditions of AcD (25?75% HH-to-vinasse mixture ratio; 1.0?g?L?1 YE; 15?g?L?1 SBFA and 100?0% HH-to-Vinasse; 1.5?g?L?1 YE; 45?g?L?1 SBFA) led to the production of 0.279 and 0.267?Nm3 of CH4 per kg of chemical oxygen demand (COD) with an energy surplus of 0.43 and 0.34?MJ?kg?SB?1, respectively. Adsorption experiments using SBFA were carried out and showed this residue could adsorb up to 61.71 and 17.32?mg?g?1 of 5-hydroxymethyl-2-furfuraldehyde and 2-furfuraldehyde, thereby reducing toxicity and improving biogas production

Production of biogas (methane and hydrogen) from anaerobic digestion of hemicellulosic hydrolysate generated in the oxidative pretreatment of coffee husks.

Ozone pretreatment of coffee husks (CH) was evaluated to generate hydrolysates for biogas production and to preserve cellulose of the solid phase for 2G ethanol production. Pretreatment variables included liquid-to-solid ratio (LSR), pH and specific applied ozone load (SAOL). Considering single-stage anaerobic digestion (AD), the highest methane production (36?NmL?CH4/g?CH) was achieved with the hydrolysate generated in the experiment using LSR 10?mL/g, pH 11 and SAOL 18.5?mg?O3/g?CH, leading to 0.064?kJ/g?CH energy recovery. Due to the presence of toxic compounds in the hydrolysate, the addition of powdered activated carbon (4?g/L) to the reactor enhanced biogas production, leading to 86?NmL?CH4/g?CH yield and 0.58?kJ/g?CH energy recovery. When two-stage AD was applied, methane production resulted in 49?NmL?CH4/g?CH, with additional 19?NmL?H2/g?CH production, resulting in a net 0.26?kJ/g?CH energy recovery

Trimellitated sugarcane bagasse: A versatile adsorbent for removal of cationic dyes from aqueous solution. Part I: Batch adsorption in a monocomponent system

Trimellitated-sugarcane bagasse (STA) was used as an environmentally friendly adsorbent for removal of the basic dyes auramine-O (AO) and safranin-T (ST) from aqueous solutions at pH 4.5 and 7.0. Dye adsorption was evaluated as a function of STA dosage, agitation speed, solution pH, contact time, and initial dye concentration. Pseudo-first- and pseudo-second-order, Elovich, intraparticle diffusion, and Boyd models were used to model adsorption kinetics. Langmuir, Dubinin-Radushkevich, Redlich-Peterson, Sips, Hill-de Boer, and Fowler-Guggenheim models were used to model adsorption isotherms, while a Scatchard plot was used to evaluate the existence of different adsorption sites. Maximum adsorption capacities for removal of AO and ST were 1.005 and 0.638 mmol g−1 at pH 4.5, and 1.734 and 1.230 mmol g−1 at pH 7.0, respectively. Adsorption enthalpy changes obtained by isothermal titration calorimetry (ITC) ranged from −21.07 ± 0.25 to −7.19 ± 0.05 kJ mol−1, indicating that both dyes interacted with STA by physisorption. Dye desorption efficiencies ranged from 41 to 51%, and re-adsorption efficiencies ranged from 66 to 87%, showing that STA can be reused in new adsorption cycles. ITC data combined with isotherm studies allowed clarification of adsorption interactions

Trimellitated sugarcane bagasse : a versatile adsorbent for removal of cationic dyes from aqueous solution. Part II: batch and continuous adsorption in a bicomponent system.

In the second part of this series of studies, the bicomponent adsorption of safranin-T (ST) and auramine-O (AO) on trimellitated sugarcane bagasse (STA) was evaluated using equimolar dye aqueous solutions at two pH values. Bicomponent batch adsorption was investigated as a function of contact time, solution pH and initial concentration of dyes. Bicomponent kinetic data were fitted by the pseudo-first-order and pseudo-second-order models and the competitive model of Corsel. Bicomponent equilibrium data were fitted by the real adsorbed solution theory model. The antagonistic interactions between ST and AO in the adsorption systems studied contributed to obtain values of maximum adsorption capacity in mono- (Qmax,mono) and bicomponent (Qmax,multi) lower than unity (Qmax,multi/Qmax,mono at pH 4.5 for ST of 0.75 and AO of 0.37 and at pH 7 for ST of 0.94 and AO of 0.43). Mono- and bicomponent adsorption of dyes in a fixed-bed column was evaluated at pH 4.5. The breakthrough curves were fitted by the Thomas and Bohart-Adams original models. Desorption of ST in a fixed-bed column was studied. The results obtained from the bicomponent batch and continuous adsorption showed that the presence of ST most affected the AO adsorption than the presence of AO affected the ST adsorption

Trimellitated sugarcane bagasse : a versatile adsorbent for removal of cationic dyes from aqueous solution. Part I : batch adsorption in a monocomponent system.

Trimellitated-sugarcane bagasse (STA) was used as an environmentally friendly adsorbent for removal of the basic dyes auramine-O (AO) and safranin-T (ST) from aqueous solutions at pH 4.5 and 7.0. Dye adsorption was evaluated as a function of STA dosage, agitation speed, solution pH, contact time, and initial dye concentration. Pseudo-first- and pseudo-second-order, Elovich, intraparticle diffusion, and Boyd models were used to model adsorption kinetics. Langmuir, Dubinin-Radushkevich, Redlich-Peterson, Sips, Hill-de Boer, and Fowler-Guggenheim models were used to model adsorption isotherms, while a Scatchard plot was used to evaluate the existence of different adsorption sites. Maximum adsorption capacities for removal of AO and ST were 1.005 and 0.638 mmol g 1 at pH 4.5, and 1.734 and 1.230 mmol g 1 at pH 7.0, respectively. Adsorption enthalpy changes obtained by isothermal titration energy and entropy of adsorption were calculated. These thermodynamic parameters were also used to evaluate the adsorption mechanism at both pH values