Propionic acid production from agro-food residues using mixed cultures
- Authors
- Venegas Ferrin, Michael Fabricio
- Format
- MasterThesis
- Status
- publishedVersion
- Description
This thesis focuses on the production of odd volatile fatty acids (VFAs) from two organic waste materials: supermarket waste (SMW) and glycerol. Particular interest was given to the selective production of propionic acid (C3) using anaerobic digestion since it usually represents the main odd VFAs produced. To achieve this, anaerobic fermentation parameters such as temperature, C3 addition and co-fermentation of SMW and glycerol were tested. The samples were fermented in batch bottles and CSTR reactors at 7% dry matter. To investigate the effect of temperature on the final product distribution, SMW was acidified at 35?C, and 40?C in batch mode. In addition, SMW that was frozen for one week was acidified and compared with these samples. The experiment resulted in similar product distribution among treatments indicating the feasibility of storing SMW under -20?C. The final concentrations of C3 after 18 days were 6.82, 6.62, and 7.21 g L-1 corresponding to 35?C, 40 ?C and frozen SMW respectively. On the other hand, 2 g L-1 and 4 g L-1 of C3 were applied to select propionic acid microorganisms in batch and CSTR reactors. The results showed that the addition of C3 caused a negative effect in the production of propionic acid. Finally, cofermentation among different concentrations of SMW and glycerol was performed. The ratio between glycerol and SMW tested were 1:3, 2:2, and 3:1 respectively. These tests were compared with acidification of crude glycerol and SMW. The co-acidification of both substrates resulted in the reduction of the concentration of total VFAs (TVFAs) linked with the increasing supply of glycerol. As a result, the final concentrations of C3 at 49 days were 4.62, 1.29 and 1.10 g L-1 corresponding to the 1:3, 2:2, and 3:1 glycerol:SMW ratios. However, acidification of crude glycerol and control SMW produced 1.67 g L-1 and 6.99 g L-1 of C3 correspondingly. In addition, analysis of soluble COD recovery showed a high percentage of non-identified COD. This result could be explained by unrecognized peaks in gas chromatography, which may belong majority to side products of glycerol fermentation like 1,2 and 1,3 propanediol.
- Publication Year
- 2014
- Language
- eng
- Topic
- TECNOLOG?A AMBIENTAL
QU?MICA
BIOTECNOLOG?A
BIOPRODUCTOS
- Repository
- Repositorio SENESCYT
- Rights
- openAccess
- License