Banca de DEFESA: TACIANA CARNEIRO CHAVES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : TACIANA CARNEIRO CHAVES
DATE: 23/10/2023
TIME: 09:00
LOCAL: Sala de Reuniões do Centro de Tecnologia - UFAL
TITLE:

Anaerobic co-digestion of vinasse and sugarcane molasses for H2 production

KEY WORDS:

anaerobic codigestion; acidogenic fermentation; hydrogen; experimental planning.

PAGES: 128
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SUMMARY:

The use of industrial waste containing abundant carbohydrates, lipids and proteins represents an alternative source of renewable energy that is gaining prominence today. Waste from the sugar and alcohol agroindustry, such as vinasse and sugar cane molasses, are rich in organic matter and, therefore, when subjected to the anaerobic digestion process, they can be converted into hydrogen, organic acids and methane. By maintaining control of specific operational parameters, it is possible to inhibit the formation of methane and favor the production of only H2 and/or acids. In this context, the objective of this study was to use the co-fermentation of vinasse and molasses to produce hydrogen. To this end, in a first phase (F1), based on the experimental design of the Simplex Lattice mixture, batch tests were carried out to evaluate the synergistic and/or antagonistic effects of vinasse (V) and molasses (M) in search of the best percentage composition of substrates (V100/M0 = R1, V75/M25 = R2, V50/M50 = R3, V25/M75 = R4, V0/M100 = R5) that resulted in maximum H2 production and used the highest possible percentage of vinasse, for This is the substrate that in the sugar and alcohol industry is the final residue of the process and has a great environmental impact. Based on the best condition observed in F1, a second phase (F2) was implemented, also in batch reactors. The influence of the initial concentration in terms of chemical oxygen demand (COD 6 and 9 g/L), temperature (T between 35 and 45 °C) and initial pH (5.5 and 6.5) were tested based on in a complete factorial design (23). At this stage, five response variables were evaluated, three of which were obtained from adjusting the data to the Modified Gompertz model (maximum production potential - P, maximum production rate - Rm and duration of the lag phase - ʎ). The other dependent variables were the volumetric production rate (VHPRDQOapl) and the volumetric hydrogen yield (VHYDQOapl). In F1, the results showed that the use of vinasse at 75% or more caused instability in H2 production. Maximum values of 595.63 mL-H2/g-DQOapl and 50.63 mL-H2/(g-DQOapl.d) were obtained, both verified in the V50/M50 condition, which, according to the Tukey test, these were results 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, the maximum values of P (925.05 mL-H2), Rm (1.24 mL-H2/h), VHYDQOapl (1.56 L-H2/g-DQOapl) and VHPRDQOapl (54.98 mL-H2/g-DQOapl/d) in the condition of lower temperature and higher COD and pH. The lag phase lasted from 0.00 hours (6 g/L, pH 6.5 and 35 °C) to 36.30 hours (9 g/L, pH 5.5 and 45 °C). pH was the most influential factor with a positive effect on the response variables, except under ʎ, which presented temperature as the most influential factor and pH with a negative effect. Temperature revealed a negative influential effect on responses, except under ʎ. The effect of COD was significantly positive for P, Rm and ʎ, but had negligible influence in relation to VHY and VHPR. Significant and well-adjusted linear models were obtained to relate the COD, pH and T factors with each response, all with R2 > 0.9.

COMMITTEE MEMBERS:
Presidente - 1456420 - RENATA MARIA ROSAS GARCIA ALMEIDA
Interno(a) - 3081569 - CARLOS EDUARDO DE FARIAS SILVA
Interno(a) - 1774383 - EDUARDO LUCENA CAVALCANTE DE AMORIM
Interno(a) - 1797785 - LUCAS MEILI
Externo(a) ao Programa - 2151064 - DAYANA DE GUSMAO COELHO - UFALExterno(a) à Instituição - FERNANDA SANTANA PEITER - F.M.Nassau