Banca de DEFESA: CANDIDA NATHALY CORDEIRO SOUTO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : CANDIDA NATHALY CORDEIRO SOUTO
DATE: 06/10/2023
TIME: 09:00
LOCAL: Pós-Graduação Engenharia Civil
TITLE:
Influence of Operating Conditions in Anaerobic Reactors with Attached Biomass to Obtain 1,3-Propanediol from Glycerol
KEY WORDS:
Glycerol fermentation. 1,3-propanediol. Ethanol. Organic load. Biofilm.Microbial consortium.
PAGES: 152
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:
In this work, the fermentation of glycerol by a bacterial consortium attached to silicone supports was studied in upflow anaerobic reactors in two configurations: R_T (anaerobic filter) and R_S (plug flow), operated continuously at different conditions of pH, HRT, and glycerol loads (pure and crude). Optimal conditions were established to obtain 1,3-PDO as the main product. In the R_T reactor, in addition to 1,3-PDO (maximum 0.47 mol.mol-gly -1), ethanol was produced, especially at pH above 8 and glycerol load (gly-LR) lower than 10 g.L-1.d-1 (maximum 0.20 mol.mol-gly-1). 1,3-PDO and ethanol productions were related to the bacteria adapted to the variations of gly-LR and pH during the operational period. The biofilm attached to the silicone (inoculum) had low diversity, with Pseudomonas, Lactobacillus, and Raoultella dominance. After 1 year of glycerol feeding, Pseudomonas were replaced by anaerobic bacteria, including 1,3-PDO producing genera: Lacrimispora and Clostridium (40% of the sequences). In the R_S reactor, operated with a progressive increase of gly-LR, the highest yields (on average) of 1,3-PDO were 0.43 mol.mol-gly-1 and 0.62 mol.mol-gly-1 , achieved with gly-LR of 18 and 46 g.L-1.d-1, when fed with pure and crude glycerol, respectively. The maximum productivity of 1,3-PDO (14.7 g.L-1.d-1) was obtained with crude glycerol. The biofilm attached to the silicone (inoculum) had low diversity, with dominance of Lactobacillus (70.6%) and Klebsiella/Raoultella (23.3%). After 293 days of feeding with pure glycerol, the abundance of Klebsiella/Raoultella decreased in the attached biomass and the suspension (9.7% and 7.4%, respectively). In addition, the genus Clostridium and members of the Ruminococcaceae family were the majority. After crude glycerol feeding, Clostridium was partially replaced by Eubacterium in the suspension. It remained the majority in the attached biomass, indicating that the attached-to-silicone bacteria converted glycerol into 1,3-PDO. In both reactors, non-degrading glycerol genera have also emerged, such as: Actinomyces and Eubacterium (in R_T), Anaerobacter, and Acetomaculum (sedimented biomass in R_S). These bacteria survived at the expense of cellular decay material. The results were very promising for scale-up application, even with high loads of crude glycerol. In addition to the studies in continuous reactors, batch experiments were carried out, and the trends observed in the production of 1,3-PDO and ethanol as a by-product in continuous mode were confirmed.
COMMITTEE MEMBERS:
Externa à Instituição - GIOVANA TOMMASO - USP
Externo à Instituição - JOSE LUIS SANZ MARTIN - UAM
Externa à Instituição - JULIANA CALABRIA DE ARAÚJO - UFMG
Externo à Instituição - OSMAR LUIZ MOREIRA PEREIRA FONSECA DE MENEZES
Externo à Instituição - RENATO CARRHA LEITAO - EMBRAPA
Interna - 1528727 - SAVIA GAVAZZA DOS SANTOS PESSOA