Banca de DEFESA: THAYSE FARIAS DE BARROS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : THAYSE FARIAS DE BARROS
DATE: 30/05/2022
TIME: 14:00
LOCAL: Sala de reuniões do Conselho do CTEC
TITLE:

Methane production from the co-digestion of grass juice elephant and vinasse.

KEY WORDS:

Biogas, anaerobic co-digestion, Box-Behnken planning, batch.

PAGES: 88
BIG AREA: Engenharias
AREA: Engenharia Sanitária
SUBÁREA: Tratamento de Águas de Abastecimento e Residuárias
SPECIALTY: Estudos e Caracterização de Efluentes Industriais
SUMMARY:

The production of energy by environmental sources can lead to great environmental
damage over the years. One way to reduce these damages is to use biomass as an
energy source, such as elephant grass broth (EGB) and vinasse, both of which have
great potential for energy generation. However, the use of these biomasses together
for methane still has technological challenges to be overcome. One of these obstacles
concerns the need to reduce the negative effect of the abrupt pH reduction caused by
elephant grass broth. Thus, the present study aimed to evaluate the anaerobic
codigestion of these substrates to produce methane, using batch reactors and the
sludge from a UASB reactor (Upflow Anaerobic Sludge Blanket) as inoculum. The
assembly of the reactors was carried out based on the Box-Behnken Design of
Experiment, which was chosen to optimize the experiment. This design consists of
three factors: addition of sodium bicarbonate; the proportion of substrates mix; and
inoculum concentration. Three levels of each factor were chosen: 0.05, 0.15 and 0.25
gHCO3:gCOD, for addition of sodium bicarbonate; 25:75, 50:50 and 75:25, for the
proportion of EGB and Vinasse (E:V); and 10, 15 and 20% of inoculum concentration,
in reference to the reaction volume. Through Box-Behnken planning, it was possible
to provide a response surface to evaluate the interaction between the factors and the
production of methane (CH4). The reactors were operated for 33 days, which resulted
in an accumulated production of CH4 varying between 372 and 1092 mLCH4/gSV. The
experimental design provided a quadratic regression equation with high representation
of the results given by the R2 of 0.9213. Although all factors were representative of the
model, the factor of sodium bicarbonate addition stands out, which shows its relevance
to pH buffering. Through the model, it was possible to obtain the optimal points of each
factor for the best production of accumulated CH4, being 0.19 gHCO3:gCOD,
50.78/49.22 (C/V) and 15.60%, respectively for sodium bicarbonate rate, substrates
proportion and inoculum concentration; these optimal points resemble one of the
reactors that produced the most accumulated CH4. In addition, the largest values of
CH4 production were related to the addition of sodium bicarbonate close to optimal

point, thus indicating that this factor could be a limiting factor in the increase of
accumulated CH4.

BANKING MEMBERS:
Externo à Instituição - ANDERSON CARLOS MARAFON - UFPel
Interna - 2151064 - DAYANA DE GUSMAO COELHO
Presidente - 1774383 - EDUARDO LUCENA CAVALCANTE DE AMORIM
Externa à Instituição - JULIANA SILVA MARTINS - UNICAMP