Banca de DEFESA: LEANDRO MONTEIRO DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LEANDRO MONTEIRO DOS SANTOS
DATE: 19/03/2024
TIME: 08:00
LOCAL: Sala de Reuniões 01 - LCCV
TITLE:

Application of strategies to optimize dairy wastewater treatment in open reactor by microalgae

KEY WORDS:

microalgae, filamentous fungi, whey, effluent treatment

PAGES: 90
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

The dairy industry is experiencing significant growth in various countries due to the increasing demand for milk and its derivatives, propelling the agricultural sector in both developed and developing nations. However, this surge in dairy production has environmental consequences, such as intensive consumption of natural resources, land occupation, and the generation of highly polluting effluents. An additional challenge arises with milk whey, a liquid byproduct resulting from dairy processing, requiring proper treatment and disposal. To address these issues, various strategies have been employed to treat dairy industry effluents, including aerobic and anaerobic biological processes, which present promising alternatives. Biological treatment technology, particularly through the use of microalgae, especially during tertiary (advanced) treatment, emerges as a promising option due to its efficiency in removing organic compounds, notably residual nitrogen and phosphorus from the secondary (primary) treatment process, with reduced operational costs. In this context, the present study aims to analyze the milk whey treatment process (after primary treatment) by microalgae, targeting the removal of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), seeking compliance with discharge standards required by legislation and applying optimization strategies for the process (treatment time, semi-continuous mode, co-cultivation with filamentous fungi, and the use of 1.5 vvm aeration). The experiment was conducted using the microalga Tetradesmus obliquus, as well as co-cultivation with the filamentous fungus Cunninghamella echinulata, combined with forced aeration in semi-continuous mode in an open reactor. Two organic loads were applied, C₁ and C₂ (~ COD = 550 e 2200, TN =15 e 60 and TP = 5 e 20 mg.L^-1, respecctively), representing the experiments with microalga of C_M1 and C_M2, and for the co-cultivation with fungus of C_MF1 and C_MF2. It was evident that the consortium demonstrated greater stability and higher efficiency in contaminant removal compared to the treatment system containing only the microalga, at both volumetric replacement rates (VRR) of 40% and 60%, while only 40% was viable when the microalga was used alone. Regarding the residual COD concentration, C_MF1 exhibited a COD variation in the range of 62 to 88 mg.L^-1, staying within the limits established by the European Union standard (125 mg.L^-1), while C_MF2 obtained a residual COD between 165-250 mg.L^-1, requiring another treatment step to achieve discharge standards; however, the treatment efficiency was high in both cases (> 70%). In terms of total nitrogen, both organic loads C_MF1 and C_MF2 obtained residual concentrations between 2-10 mg.L^-1, complying with European legislation discharge standards (10 mg.L^-1). Finally, for total phosphorus, similarly to COD, C_MF1 was efficiently treated, with residual concentrations between 0.65-0.9 mg.L^-1 meeting European legislation (between 1-2 mg.L^-1), while for C_a, residual values ranged from 2-3.5 mg.L^-1, indicating the need for additional treatment. This raises a question: if total nitrogen was removed in both organic loads, COD and total phosphorus may not have been removed due to the limitation of this cellular macrocomponent, hence studying the COD:N:P ratio of the effluent is necessary in subsequent studies. The obtained dry cell weight varied between 300-900 mg.L^-1 and can be used for biotechnological applications. Finally, during co-cultivation, there was greater system buffering with less pH variation, ensuring greater system stability.

COMMITTEE MEMBERS:
Interno(a) - 3081569 - CARLOS EDUARDO DE FARIAS SILVA
Interno(a) - 1456420 - RENATA MARIA ROSAS GARCIA ALMEIDA
Externo(a) ao Programa - 1296115 - ALBANISE ENIDE DA SILVA - UFALExterno(a) à Instituição - BRIGIDA MARIA VILLAR DA GAMA - UFAL