Method development for assessment of membrane characteristics in Membrane Bioreactor (MBR)

• Autor(a) principal: Mello, Igor Penido de
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/124059
• topic: Submerged membrane bioreactor; wastewater; fouling; critical flux; sustainable flux; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

Membrane bioreactors treat wastewater and produce effluent with quality above traditional methods. Their cost, however, remains higher than competing processes. The occurrence of membrane fouling contributes to these costs insofar as it increases the need for membrane area and air scouring. Manufacturers thus require environments comparable to real plant conditions in order to test products that overcome these drawbacks. This work aimed, in this context, to develop a filtration method that could be used to investigate the characteristics and resistance to fouling of different membranes. The project involved the identification of causes for the difficulties observed in previous attempts, the pursue of solutions, their integration in the system and finally the execution of several filtration trials. Diverse filtration protocols explored the behaviors of polyethersulfone laminated flat membrane sheets through permeation in different media: water, bentonite suspension and activated sludge. These protocols, based on flux-step methods, determined the rate of transmembrane pressure rise, which characterizes fouling, to then assess parameters such as the critical and sustainable fluxes. The method validated the different behaviors of two membrane materials, namely polyethersulfone and polyvinylidene fluoride, which had very different permeabilities, similar values for the critical flux but distinct sustainable fluxes. The higher sustainable flux of the polyvinylidene fluoride membranes was due to lower residual fouling rates, reflecting the higher resistance of this material to irreversible sorption of macromolecules and colloids. The setup built may be improved to allow the simultaneous testing of two membrane sheets. Yet, the method constructed can possibly be applied to differentiate membranes of varied materials, evaluate the effect of aeration intensity or asses sludge filterability.