Name: GUSTAVO HENRIQUE LOUREIRO FERREIRA
Publication date: 22/03/2017
Advisor:
Name |
Role |
|---|---|
| RICARDO FRANCI GONÇALVES | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| RAQUEL MACHADO BORGES | External Examiner * |
| RICARDO FRANCI GONÇALVES | Advisor * |
| SÉRVIO TÚLIO ALVES CASSINI | Internal Examiner * |
Summary: The anaerobic digestion of microalgae is pointed out as a promising sustainable biofuel production option and hence a possible solution for the forecasted fossil fuels shortage. Besides diminishing the effects of greenhouse gas emission on the atmosphere, biogas production from anaerobic digestion of microalgae produced from wastewater treatment is also capable of preventing the eutrophication of receiving water bodies, generating a better-quality final effluent. The hydrolysis stage is considered to be the limiting stage of anaerobic digestion processes, having its effect minimized by pretreatments that can hydrolyze the substrate before its digestion. This research aims to verify pretreatment effects on the production of methane from anaerobic digestion, besides characterizing the biomass before and after the thermal and alkaline hydrolytic processes. This study is part of a conception proposal of an energy producing Wastewater Treatment Plant (WWTP), located on Araçás WWTP Vila Velha/ES. The biomass used presented 3,5% solid concentration and a mean Chemical Organic Demand (COD) value of 36,6g/L. Although presenting less organic matter and carbohydrates solubilization, the thermal hydrolysis presented a higher methane production, producing 1,10gCODCH4/gVSS.d, 61% more than the production by the biomass not submitted to any hydrolytic pretreatment (0,68gCODCH4/gVSS.d). The alkaline hydrolyzed biomass produced 0,88gCODCH4/gVSSV.d, only 29% higher than the biomass not submitted to hydrolysis. These results confirm the thermal hydrolysis as a more suitable option than the chemical alkaline hydrolysis. The energy balance generated from these results produced an Energy Return on the Investment (EROI) of 5,2 for biomass not submitted to pretreatments, 5,5 for biomass submitted to thermal hydrolysis and 5,3 for the alkaline treatment, pointing out this WWTP, based on the proposed technology, as an energy producer.
