This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pre-treatment of sugarcane straw for 2G ethanol production) in a semi-Continuous Stirred Tank Reactor (s-CSTR) aiming to provide optimum operational parameters for continuous CH 4 production. Using filter cake as co-substrate may allow the reactor to operate throughout the year, as it is available in the sugarcane off-season, unlike vinasse. A comparison was made from the microbial community of the seed sludge and the reactor sludge when CH 4 production stabilized. Lactate, butyrate and propionate fermentation routes were denoted at the start-up of the s-CSTR, characterizing the acidogenic phase: the Oxidation-Reduction Potential (ORP) values ranged from -800 to -100 mV. Once the methanogenesis was initiated, alkalizing addition was no longer needed as its demand by the microrganisms was supplied by the alkali-characteriscs of the deacetylation liquor. The gradual increase of the applied Organic Load Rates (OLR) allowed stabilization of the methanogenesis from 3.20 gVS L -1 day -1 : the highest CH 4 yield (230 NmLCH 4 gSV -1 ) and average organic matter removal efficiency (83% + 13) was achieved at ORL of 4.16 gVS L -1 day -1 . The microbial community changed along the reactor operation, presenting different metabolic routes mainly due to the used lignocellulosic substrates. Bacteria from the syntrophic acetate oxidation (SAO) process coupled to hydrogenotrophic methanogenesis were predominant (~ 2% Methanoculleus) during the CH 4 production stability. The overall results are useful as preliminary drivers in terms of visualizing the co-AD process in a sugarcane biorefinery integrated to scale.
-Solid-state cultivation (SSC) may be defined as growth of microorganisms on a solid support impregnated or not with a nutrient solution in near absence of free-water conditions. The use of sugarcane bagasse as a support for SSC usually demands that the particles are impregnated and moistened with nutrient solution. Vinasse is the main wastewater of ethanol fermentation-distillation. As there are no reports of the use of wastewater for moistening solid supports in SSC, the proposal is the development of an innovative process, with valuation of these by-products. Thus, the aim of this research was to evaluate SSC of Aspergillus niger using sugarcane bagasse and vinasse for citric acid production. The results indicate that citric acid production and glucose consumption are dependent on oxygen availability, which can be modulated by selection of bed height and air-flow in packed-bed bioreactors.
This is a pioneer study evaluating the methane (CH 4 ) production potential from residues of integrated 1 st (vinasse and filter cake) and 2 nd (deacetylation pretreatment liquor from straw) generation (1G2G) sugarcane biorefinery, providing a fully chemical characterization of them and their relation with the anaerobic digestion (AD) process.Small-scale assays provided fundamentals for basing the co-digestion optimization by assessing the optimal co-substrates synergistic conditions. Biochemical Methane Potential (BMP) tests showed co-digestion enhanced CH 4 yield of isolated substrates, reaching up to 605 NmLCH 4 gVS -1 . The association of vinasse and deacetylation liquor as co-substrates increased the BMP by ~38% mostly by nutritionally benefiting the methanogenic activity. The kinetic analysis confirmed that the deacetylation liquor was the co-substrate responsible for improving the CH 4 production in the co-digestion systems due to the highest CH 4 conversion rate. The alkaline characteristic of the liquor (pH~12) also prevented alkalizing from being added to the co-digestion, an input that normally makes the process economically unfeasible to implement on an industrial scale due to the large quantities required for buffering the reactor. The filter cake had the lowest BMP (262 NmLCH 4 gVS -1 ) and digestibility (< 40%), further limited by the required stirring to improve the mass transfer of biochemical reactions. The present study drives towards more sustainable use of vinasse, the most voluminous waste from the sugarcane industry, and lignin-rich residues derived from pre-treatment alkaline methods, aiming at an energy-efficient utilization, by at least 16% when compared to the traditional vinasse AD. The experimental and modeling elements from this work indicated the lignin-rich liquor is the main responsible for putting the co-digestion as a disruptive technological arrangement within the 1G2G sugarcane biorefineries, .
Brazil's agriculture and livestock annually generates enormous amounts of biomass, which varies in its biochemical composition. Many studies have pointed out the benefits of using this biomass as a substrate for biogas production through anaerobic digestion (AD), mostly via the co‐digestion (co‐AD) pathway. The agriculture and livestock of southeastern Brazil – sugarcane, orange, corn, soybean, coffee, cattle, swine, and poultry – have together demonstrated their potential for producing biomass that can be used for maximizing methane production. Filter cake, vinasse, straws, bagasse, mucilage, pulp, washing water, thin stillage, and manures also have specific organic matter and nutrient content that can be evaluated from an economic perspective as co‐products of biorefineries. Some are costless but others have acquisition costs in the agricultural market. Comparing the recent biochemical compositions cited in scientific literature (technical parameter) and to know the costs (valuation parameter) is crucial for farmers and investors make decisions in large‐scale. This study conducted a bibliographical survey of biomass generated in Brazilian agroindustry as a co‐substrate for energy production. The analysis summarized two tables: 1‐ a compilation of biochemical composition of the main co‐substrates, and 2‐ the acquisition or opportunity costs, discussing innovative aspects in the context of biogas production. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.
ResumoAplicação das correntes líquidas residuárias da biorrefinaria de cana-de-açúcar (1G2G) na digestão anaeróbia visando a produção de biogás e, consequentemente, bioenergia. A codigestão desses resíduos orgânicos possibilita melhorar o rendimento de metano e reduzir potenciais efeitos inibitórios de determinados resíduos.
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