Estratégias para recuperação de fluxo de membranas de ultrafiltração aplicadas à separação de biomassa microalgácea cultivada com esgoto sanitário

• Ano de defesa: 2023
• Autor(a) principal: Azeredo, Ludimila Zotele
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Engenharia Ambiental; Centro Tecnológico; UFES; Programa de Pós-Graduação em Engenharia Ambiental
• Palavras-chave em Português: Tratamento de esgoto sanitário; Microalgas; Ultrafiltração; Pré-tratamento; Fouling; subject.br-rjbn; Engenharia Sanitária
• Link de acesso: http://repositorio.ufes.br/handle/10/16575

The improvement of sustainable technologies based on the NEXUS and Circular Economy concepts is a strategic need to mitigate water and energy insecurity in various regions of the planet. The objective of this work was to optimize the ultrafiltration of a microalgae suspension through the implementation of flow recovery strategies using coagulants and steel industry residues to control the formation of deposits. This suspension corresponds to the effluent from a sanitary sewage treatment plant on a pilot scale through a UASB reactor and followed by two high rate lagoons. The average concentration of SSV in the suspension produced in the LAT was 120 mg/L, being composed of a heterogeneous biomass with the majority presence of Chlorella sp. In the first stage of the research, physical methods such as aeration, relaxation and backwashing were tested to recover the flow and control deposits on the ultrafiltration membranes. Aeration at the base of the membranes increased the tangential velocity by 47% compared to filtration without any technique for reducing and controlling deposits. The average flows were 68.9 L/m².h, 63.2 L/m².h and 55.7 L/m².h, aeration, relaxation and backwash, respectively. In the second stage, the use of coagulants and steel industry residues in the pre-treatment of the suspension with microalgae and their effects on flow recovery and deposit control were studied. The coagulation-flocculation-sedimentation process influenced the characteristics of the flocs, and the average final normalized fluxes of the coagulated suspensions. The tannin-based coagulant increased the resistance imposed by deposits on the membrane, even though most deposits were reversible. Finally, the influence of pre-treatment of the suspension on the ultrafiltration of microalgae grown in sanitary sewage on the physical methods of flow recovery and deposit control was verified. The use of residues rich in calcium as coagulants caused lower membrane resistance. Although there was an increase in irreversible deposits with the addition of inorganic coagulants based on aluminum and calcium, the predominant mechanism in the formation of deposits was the formation of the cake layer. For the three control strategies investigated, the lowest formation of deposits on the membrane was observed in the backwash filtration of the suspension coagulated with 10 mg/L with bag filter powder.