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A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors.

Huang J, Wang Z, Zhang J, Zhang X, Ma J, Wu Z - Sci Rep (2015)

Bottom Line: The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation.The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR.The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092, P.R. China.

ABSTRACT
Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

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Comparison of TMP evolution between two MBR systems.
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f5: Comparison of TMP evolution between two MBR systems.

Mentions: Fig. 5 illustrates the evolution of TMP in the two MBR systems. Compared with the control MBR, membrane fouling in the electrochemical MBR (with electric field) was significantly reduced during long-term operation. At stage 1 with specific aeration demand by projected membrane area (SADm) 100 m3/(m2·h), the average mixed liquor suspended solids (MLSS) concentration was maintained at 6.4 g/L for the control MBR and 6.7 g/L for the electrochemical MBR. At this stage, the membrane in the electrochemical MBR was cleaned twice during 45 d operation, while the control MBR underwent three cleaning procedures. At stage 2, for the control MBR and the electrochemical MBR, the average MLSS concentrations were 6.7 g/L and 7.3 g/L, respectively. At this stage, the duration of an operation cycle for both two membranes was extended (Fig. 5). This was because that the SADm was increased from 100 m3/(m2·h) at stage 1 to 150 m3/(m2·h) at stage 2. An increase of SADm can lead to an increased cross-flow velocity (CFV) along membrane surfaces and thus an improved filtration performance231. A higher CFV can induce a greater shear stress along membrane surfaces, which can dislodge deposited foulants and reduce fouling32. Tran et al. reported that the cake resistances under shear stresses of 0.9, 2.6 and 4.9 kPa were 56, 27 and 9 × 1011 m−1, respectively33. It can be also observed that the operation cycle for the membrane in this electrochemical MBR was extended to 46 days, which was much longer than the membrane operated in the control MBR (25 days on average) at stage 2. The long-term performance of this electrochemical MBR again confirmed that this conductive MF membrane with electrical field could efficiently mitigate membrane fouling.


A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors.

Huang J, Wang Z, Zhang J, Zhang X, Ma J, Wu Z - Sci Rep (2015)

Comparison of TMP evolution between two MBR systems.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4363883&req=5

f5: Comparison of TMP evolution between two MBR systems.
Mentions: Fig. 5 illustrates the evolution of TMP in the two MBR systems. Compared with the control MBR, membrane fouling in the electrochemical MBR (with electric field) was significantly reduced during long-term operation. At stage 1 with specific aeration demand by projected membrane area (SADm) 100 m3/(m2·h), the average mixed liquor suspended solids (MLSS) concentration was maintained at 6.4 g/L for the control MBR and 6.7 g/L for the electrochemical MBR. At this stage, the membrane in the electrochemical MBR was cleaned twice during 45 d operation, while the control MBR underwent three cleaning procedures. At stage 2, for the control MBR and the electrochemical MBR, the average MLSS concentrations were 6.7 g/L and 7.3 g/L, respectively. At this stage, the duration of an operation cycle for both two membranes was extended (Fig. 5). This was because that the SADm was increased from 100 m3/(m2·h) at stage 1 to 150 m3/(m2·h) at stage 2. An increase of SADm can lead to an increased cross-flow velocity (CFV) along membrane surfaces and thus an improved filtration performance231. A higher CFV can induce a greater shear stress along membrane surfaces, which can dislodge deposited foulants and reduce fouling32. Tran et al. reported that the cake resistances under shear stresses of 0.9, 2.6 and 4.9 kPa were 56, 27 and 9 × 1011 m−1, respectively33. It can be also observed that the operation cycle for the membrane in this electrochemical MBR was extended to 46 days, which was much longer than the membrane operated in the control MBR (25 days on average) at stage 2. The long-term performance of this electrochemical MBR again confirmed that this conductive MF membrane with electrical field could efficiently mitigate membrane fouling.

Bottom Line: The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation.The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR.The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092, P.R. China.

ABSTRACT
Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

Show MeSH