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    Codigestão anaeróbia de vinhaça e melaço de cana-de-açúcar para produção de h2
    (INSTITUTO FEDERAL DE ALAGOAS - Ifal, 2023-10-23) Chaves, Taciana Carneiro; Amorim, Eduardo Lucena Cavalcante de; https://orcid.org/0000-0002-7349-9055; http://lattes.cnpq.br/5647462671079561; Almeida, Renata Maria Rosas Garcia; https://orcid.org/0000-0003-1331-8619; http://lattes.cnpq.br/3745446778086537; Silva, Carlos Eduardo de Farias; http://lattes.cnpq.br/0395823528382046; Meili, Lucas; http://lattes.cnpq.br/3802018064427795; Coelho, Dayana de Gusmão; https://orcid.org/0000-0002-5170-3449; http://lattes.cnpq.br/1255714800013638; Peiter , Fernanda Santana; http://lattes.cnpq.br/0958176908010538
    Industrial residues abundant in carbohydrates, lipids, and proteins are currently gaining prominence as alternative sources of renewable energy. Wastes from the sugar and alcohol agroindustry, such as vinasse and sugarcane molasses, are rich in organic matter and, therefore, when subjected to the anaerobic digestion process, can be converted into hydrogen, organic acids, and methane. Maintaining control of specific operational parameters enables the inhibition of methane formation and favors H2 and acid production. In this context, the objective of this study was to use the co-fermentation of vinasse and molasses to produce hydrogen. To this end, the first phase of the work (F1) consisted of the experimental planning of the Simplex Lattice mixture with batch tests to evaluate the synergistic and antagonistic effects of vinasse (V) and molasses (M). The purpose of this step was to find the percentage composition of the substrates (100% vinasse: V100/M0 = R1, 75% vinasse + 25% molasses: V75/M25 = R2, 50% vinasse + 50% molasses: V50/M50 = R3, 25% vinasse + 75% molasses: V25/M75 = R4, 100% molasses: V0/M100 = R5) that would result in maximum H2 production besides using the highest possible percentage of vinasse, given the significative environmental impact of this final residue from the sugar and alcohol industry. From the best condition verified in F1, the second phase (F2), also in batch reactors, tested the influence of the initial concentration regarding chemical oxygen demand (COD 6 and 9 g/L), temperature (T between 35 and 45 °C) and initial pH (5.5 and 6.5) based on a full factorial design (23). The study evaluated two response variables: the volumetric production rate (VHPRCODapl) and the volumetric hydrogen yield (VHYCODapl). Results obtained in F1 showed that using vinasse at 75% or more caused instability in H2 production. The maximum values of 595.63 mL- 2/g-CODapl and 50.63 mL-H2/(g-CODapl.d) occurred in the V50/M50 condition, which, according to the Tukey test, were statistically similar to those observed at V25/M75 and V0/M100. Vinasse and molasses interacted synergistically in the mixtures. Highly significant (p ≤ 0.05) quadratic models with good fits were obtained for yield (R2 = 0.98) and H2 production rate (R2 = 0.92). In F2, with the initial composition of the feed fixed at 50% of each substrate, maximum values of VHYCODapl (1.56 L-H2/g-CODapl) and VHPRDQOapl (54.98 mL-H2/g-CODapl/d) were recorded in the condition of lower temperature and higher COD and pH. pH was the factor that exerted the greatest influence with a positive effect on the response variables, while temperature revealed a negatively influential effect. The effect of COD was negligible concerning VHY and VHPR. The linear models obtained were significant and well adjusted (with R2 coefficients above 0.9), relating the factors COD, pH, and temperature.