RT info:eu-repo/semantics/article
T1 Fouling analysis and mitigation in a tertiary MBR operated under restricted aeration
A1 Vera Peña, Luisa María
A2 Ingeniería Química y Tecnología Farmacéutica
A2 Grupo de investigación Tratamiento y reutilización de aguas
K1 Backwashing aided by air-scouring
K1 Compressible cake
K1 Sludge bioflocculation
K1 Residual fouling control
K1 transmembrane
K1 pressure set-point
AB Operation of tertiary membrane bioreactors at low dissolved oxygen concentration (DO) reduces energyconsumption associated with biological aeration. However, low oxygen concentrations affect biological activity,sludge bioflocculation and fouling propensity. This study assesses the effectiveness of an alternative backwashinitiation strategy for fouling control in a tertiary membrane bioreactor operated under restricted oxygenation.Long-term filtration tests were carried out at five DOs (0.09–1.23 mg/L) in a pilot-scale unit operated in dead-end filtration mode (i.e. without air-scouring) under a broad-range of permeate fluxes (25–65 L/h m2 ).Bioflocculation was negatively affected at low DO ([O2]≤0.25 mg/L), resulting in relatively high values ofbiopolymeric clusters concentration (BPC ≥4.3 mg DOC/L). This produced small floc sizes (D (v,0.5)≤49 μm),poor filterability (TTF≥573 s) and low critical fluxes (Jc≤20 L/h m2 ). However, above moderate oxygenconcentrations ([O2 ]≥0.38 mg/L), sludge bioflocculation significantly increased, showing good filterability(TTF≤173 s) and relatively high critical fluxes (Jc≥45 L/h m 2). The filtration tests showed that the controlledbackwashing initiation was effective in limiting the residual fouling even at a very low oxygen concentration,since it automatically increased backwashing frequency as sludge bioflocculation decreased. The reversiblefouling, it can be described by the compressible cake model, with a specific cake resistance at zero pressuregoverned by the bioflocculation state, while the compressibility is determined by the filtration flux. Optimalsustainable conditions were established at moderate DO ([O2]=0.38 mg/L), which involves a low specific energydemand for the filtration process and biological aeration (SED=0.25 kWh/m 3), and a high net permeate flux (J=42.2 L/h m 2).
SN 0376-7388
YR 2017
FD 2017
LK http://riull.ull.es/xmlui/handle/915/39934
UL http://riull.ull.es/xmlui/handle/915/39934
LA en
DS Repositorio institucional de la Universidad de La Laguna
RD 29-nov-2024