Membrane fouling reduction and improvement of sludge characteristics by bioflocculant addition in submerged membrane bioreactor

Abstract

a b s t r a c tThe effectiveness of a green bioflocculant (Gemfloc Ò ) on enhanced performance of a submerged membrane bioreactor (SMBR) was evaluated in terms of membrane fouling reduction and sludge characterization. Two MBRs were operated parallelly in this study, namely conventional MBR (CMBR) and MBR with Gemfloc Ò addition (MBR-G). Results showed mitigated membrane fouling through Gemfloc Ò addition in terms of cake layer formation and pore blocking. When compared to the CMBR, in spite of more extracellular polymeric substances (EPS) presented in activated sludge, the MBR-G demonstrated less soluble microbial products (SMP), larger sludge flocs, higher zeta potential and greater relative hydrophobicity of sludge flocs, which decreased cake layer resistance and pore blocking resistance. The reduced cake layer resistance in the MBR-G could be also ascribed to less growth of suspended biomass, lower sludge viscosity, as well as less EPS, SMP and biopolymer clusters in the cake layer. In addition, a modified resistance-in-series model was employed by considering SMP and mixed liquor suspended solids. The simulated results implied that the model could predict the influence of sludge characteristics on membrane fouling behavior of the SMBR.

Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment

“…Where J is the permeation flux (m 3 m -2 h -1 ); P is the transmembrane pressure (Pa); is the dynamic viscosity of the permeate (Pa s); R T is total resistance (m -1 ); R M is the intrinsic membrane resistance (m -1 ); R C is the cake layer resistance (m -1 ); and R P is the pore blocking resistance (m -1 ). The method described by Deng et al [20] was adopted…”

Impact of reactor configurations on the performance of a granular anaerobic membrane bioreactor for municipal wastewater treatment

“…Based on the resistance-in-series model, fouling resistance of the G-AnMBR was determined after G-AnMBR experiments by using measurement protocol proposed by Deng et al (2015) and applying Eqs. (1) and (2) (Choo and Lee, 1996):…”

“…The accumulation of SMP P could change the surface charge and morphology of the membrane, promoting the adhesion and growth of sludge flocs as cake layer (Deng et al, 2014;Liu et al, 2012). Furthermore, the build-up of SMP C could result in irreversible fouling by forming a thin gel layer on the membrane surface (Deng et al, 2015). Results implied that EPS P , SMP P and SMP C were the main contributors to the higher R C in the SG-AnMBR.…”

Preparation, Performances, and Mechanisms of Microbial Flocculants for Wastewater Treatment

“…Due to the reduction of the surface charge of the particles, that is, the Zeta potential is reduced, the repulsive force between the particles is reduced [151,152]. By the attraction of van der Waals, colloid and suspended solids gathered to form flocs, then the colloid destabilization, after this, colloids and colloid, or colloid and microbial flocculant were flocculated into large particles [153,154]. The flocculation effect can be influenced by the pH value of the flocculation reaction system due to the change of the water colloid or flocculant [155][156][157][158].…”