Membrane fouling mechanisms in the process of using flat-sheet membrane for simultaneous thickening and digestion of activated sludge

Wang, Xinhua; Wu, Zhichao; Wang, Zhiwei; Du, Xingzhi; Hua, Juan

doi:10.1016/j.seppur.2008.07.013

Cited by 28 publications

(14 citation statements)

References 33 publications

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“…A sudden rise of TMP could be attributed to the irreversible fouling introduced by the deposition of biopolymers such as SMP even at sub-critical flux conditions. In our previous experiment, it has been demonstrated that the deposition of EPS on the membrane surface was uneven in the MSTD reactor [35]. The membrane surface may be divided into different parts due to the uneven deposition of EPS, i.e.…”

Section: Identification Of Sustainable Fluxmentioning

confidence: 97%

Identification of sustainable flux in the process of using flat-sheet membrane for simultaneous thickening and digestion of waste activated sludge

Wang

et al. 2009

Journal of Hazardous Materials

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Section: Identification Of Sustainable Fluxmentioning

confidence: 97%

Identification of sustainable flux in the process of using flat-sheet membrane for simultaneous thickening and digestion of waste activated sludge

Wang

et al. 2009

Journal of Hazardous Materials

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“…It was reported that SMP (as shown in Fig. 4) played an important role in formation of the fouling layer [22,23], and larger floc size was in favor of the reduction of fouling layer. Thus, the decline of R c at higher Ca:Mg ratio was mainly due to the reduction of SMP and increase of floc size by enhancing bioflocculation of Ca 2+ .…”

Section: Resistance Distributionmentioning

confidence: 96%

“…2). It has been well recognized that the higher SMP concentration results in the poorer filterability and more severe membrane fouling [22,23]. Based on the fact that the dosage of divalent cations was constant at 200 mg/L, the increase of SMP and decrease of BEPS with the decline of Ca:Mg ratio might be indicated that Ca 2+ was more beneficial to binding and bridging EPS compared with Mg 2+ .…”

Section: Epsmentioning

confidence: 99%

Impact of calcium-to-magnesium ratio on the performance of submerged membrane bioreactors

Wang

Chen

Qian

et al. 2012

Desalination and Water Treatment

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A B S T R A C TThe performances of membrane bioreactors (MBRs) were compared in bench-scale submerged MBRs treating synthetic wastewater at three Ca:Mg ratios of 3:1, 1:1, and 1:3 with constant divalent cations of 200 mg/L. The dosages of Ca 2+ were 150, 100, and 50 mg/L, corresponding to Mg 2+ of 50, 100, and 150 mg/L for Ca:Mg ratios of 3:1, 1:1, and 1:3, respectively. The results showed that Ca:Mg ratio had a slight impact on effluent quality, while membrane fouling was effectively mitigated by enlarging Ca:Mg ratio due to the decline of fouling layer resistance. When Ca:Mg ratio declined from 3:1 to 1:3, the concentration of soluble microbial products (SMP) significantly increased, while the particle size of flocs decreased. SMP and particle size correlated well with the variation of membrane fouling. The carbohydrate in SMP and bound extracellular polymeric substances (BEPS) changed significantly with the decline of Ca:Mg ratio, while the protein in SMP and BEPS varied slightly, suggesting that the divalent cations were more prone to bridging carbohydrate compared with protein. In comparison with Mg 2+ , Ca 2+ had a more significant impact on mitigating membrane fouling, because Ca 2+ was more beneficial to binding and bridging negatively charged functional groups in extracellular polymeric substances such as carbohydrate.

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“…Whilst it is generally recognised that higher mixed liquor suspended solids (MLSS) concentrations tend to depress foulant levels, manifested as soluble microbial product (SMP), such observations have tended to be limited to moderate MLSS concentrations of up to 25 g L -1 (Yeom et al, 2005;Schwarz et al, 2006). A body of work specifically on simultaneous aerobic digestion and thickening of WAS (Wang et al, 2008(Wang et al, , 2009Wu et al, 2009) was focused largely on the soluble foulant levels, manifested as soluble microbial product (SMP) and colloidal and/or soluble chemical oxygen demand (sCOD), and bulk sludge quality parameters such as viscosity and capillary suction time (CST). Results showed SMP and sCOD to significantly influence membrane fouling.…”

Section: Introductionmentioning

confidence: 99%

Biological treatment and thickening with a hollow fibre membrane bioreactor

et al. 2014

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Aerobic operation of an immersed hollow fibre membrane bioreactor, treating municipal wastewater supplemented with molasses solution, has been studied across mixed liquor suspended solids (MLSS) concentrations between 8 and 32 g L(-1), the higher concentrations being normally associated with thickening operations. Only a marginal loss in membrane permeability was noted between 8 and 18 g L(-1) when operation was conducted without clogging. The sustainable operational flux attainable above 18 g L(-1) was highly dependent upon both the MLSS concentration and the state of the membrane. A temperature-corrected flux of 28 L m(-2) h(-1) (LMH) was sustained for 18 h at an MLSS of 8 g L(-1) using membranes close to initial their virgin-state permeability. This value decreased to around 14 LMH at 20 g L(-1) and 5 LMH at 32 g L(-1) MLSS for an aged membrane whose permeability had been recovered following clogging. Below the threshold flux operation without significant clogging was possible, such that the membrane permeability could be recovered with a chemically enhanced backflush (CEB). Above this flux clogging took place at a rate of around 7-14 g solids per m(2) membrane per m(3) permeate volume passed irrespective of the MLSS concentration. The permeability of the unclogged membrane was depressed and could not be recovered using a standard CEB, indicative of irrecoverable pore clogging. The outcomes corroborated previously reported observations concerning the deleterious long-term impacts of clogging, and confirmed the critical importance of operation at a sustainable flux value.

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Membrane fouling mechanisms in the process of using flat-sheet membrane for simultaneous thickening and digestion of activated sludge

Cited by 28 publications

References 33 publications

Identification of sustainable flux in the process of using flat-sheet membrane for simultaneous thickening and digestion of waste activated sludge

Identification of sustainable flux in the process of using flat-sheet membrane for simultaneous thickening and digestion of waste activated sludge

Impact of calcium-to-magnesium ratio on the performance of submerged membrane bioreactors

Biological treatment and thickening with a hollow fibre membrane bioreactor

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