Banca de DEFESA: ANTONIO GUSTAVO DOS SANTOS NETO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANTONIO GUSTAVO DOS SANTOS NETO
DATE: 20/04/2023
TIME: 14:00
LOCAL: Pós-Graduação Engenharia Civil
TITLE:

Formation of Microalgae-Bacterial Aggregates in High Rate Algal Ponds Aiming at the Recovery of Resources and Wastewater Treatment

KEY WORDS:

Sewage treatment; Resource recovery; High Rate Algal Ponds; Microalgae bacteria aggregates; bioflocculation.

PAGES: 136
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

High Rate Algal Ponds (HRAP) for sewage treatment and microalgae production are a technology that has been studied since the 1950s. In these systems, the biomass can be used as several value-added products. However algae harvesting is still a challenge, once it is an expensive process, which often uses chemical products or demands a lot of energy. The present work proposes a biological alternative to be applied in HRAP in order to improve the efficiency of biomass harvesting, allowing sewage treatment and resource recovery, which are the microalgae-bacteria aggregates. In the first stage, a strategy was developed for the formation of these structures, which consisted of inoculating 50L HRAPs with activated sludge, and no need for microalgae inoculation. In addition, the systems were operated with biomass recirculation. From this experiment, it was observed that the applied conditions were favorable for the formation of aggregates, which demonstrated SVI30 of 32.0±5.0 mL.g-1, flocculation efficiency of 77.5±6.3%, and COD removal and ammoniacal nitrogen around 80%. Moreover, the formed aggregates contained chlorophytes, cyanobacteria and diatoms, and the protein fraction of EPS was associated with its formation process. The second and third stages of this study evaluated the effect of inoculation with the use of activated sludge, as well as the increase in water depth, on the biomass formation process, sedimentability, sewage treatment and resource recovery. For this, 3 high-rate ponds fed with effluents from a UASB reactor were operated: the first was not inoculated, had a usable volume of 2.4m³ and a usable depth of 0.3m (LAT30SL); the second was inoculated with activated sludge, had a usable volume of 2.4m³ and usable depth of 0.3m (LAT30CL); the third, which was also inoculated with activated sludge, had a usable volume of 4m³ and a useful height of 0.5m (LAT50CL). The operational strategy at all stages consisted in an initial operation for biomass formation, followed by operation in a continuous regime. In this way, both the insertion of activated sludge and the increase in pond depth, contributed to control pH and dissolved oxygen. Filamentous microalgae were associated with the aggregate formation process in LAT30CL and LAT50CL. The sedimentability assessment demonstrated that LAT30CL and LAT50CL obtained higher efficiencies (82% and 92%) than the conventional HRAP – LAT30SL (63%). Besides, it was also observed that the increase in depth contributed to the increase in solids and chlorophyll a productivity. Ponds inoculated with sludge also indicated more efficient in organic matter removal, however they contained nitrate due to nitrification activity. The three systems behaved similarly in nutrient recovery, obtaining higher concentrations of evaluated compounds when compared to the sludge used for inoculum.

COMMITTEE MEMBERS:
Externo à Instituição - GUSTAVO HENRIQUE RIBEIRO DA SILVA - UNESP
Presidente - 3133998 - BRUNA SCANDOLARA MAGNUS
Externa ao Programa - 1061125 - ELIZABETH AMARAL PASTICH GONCALVES - nullExterno à Instituição - MARCIO GOMES BARBOZA - UFAL
Externa à Instituição - MARIA LÚCIA CALIJURI - UFV