Name: GISELE GAVAZZA LAMBERTI
Publication date: 23/03/2017
Advisor:
Name |
Role |
|---|---|
| RICARDO FRANCI GONÇALVES | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| RICARDO FRANCI GONÇALVES | Advisor * |
| SÉRVIO TÚLIO ALVES CASSINI | Internal Examiner * |
Summary: Aiming to optimize the algal biomass biodegradability during anaerobic digestion, several hydrolysis processes have been studied, promoting increase of energy production by the hydrolysis of algae cells and subproducts generation. This research has the propose to perform thermal and alkaline pretreatment of the algae biomass in order to increase the algae biodegradability in the anaerobic digestion process through the organic carbon, nitrogen and phosphorus solubilization. This project is part of the energy efficiency analysis of a wastewater treatment plant located in Vila Velha-ES, aiming to reduce the demand of energy during the treatment processes. The mixotrophic algal sludge collected for this research presented a total solids concentration of 35.1 g / L, which were analyzed for organic matter solubilization (CODs), nutrients and exopolymers. For this research, thermal hydrolysis at 90 ° C solubilized 19% of CODs, while in the alkaline process at pH 12, it increases to 21%. There was increasing solubilization of carbohydrates with the increase of temperature in thermal pretreatment, but the same pattern was not observed during the alkaline pretreatment. The color of the biomass changed from green to brown during the treatments, which suggests that Maillard reactions occurred during the reaction time, with interactions between carbohydrates and soluble proteins. A reduction of soluble phosphate concentration in the sample along the pretreatment was identified, suggesting the precipitation of these with other cations such as Ca2+ and Mg2+, leading to the precipitation of hydroxyapatite and struvite compounds. In this way, both pretreatments showed satisfactory results regarding the solubilization of organic material, nutrients, carbohydrates and proteins. Although the alkaline pretreatment indicated better results in the solubilization of organic mattter, for the general purpose of this research, thermal processes were more efficient in promoting a better solubilization of other compounds such as nutrients, carbohydrates and proteins.
