Monitoring particulate fouling in membrane systems

In this study, different processes such as flocculation with ferric chloride (FeCl 3 ) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment to microfiltration (MF) were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index (MFI) and flux decline in MF. Flux declin of MF with seawater was 45% without any pre-treatment, 42% after pre-treatment of FeCl 3 flocculation, 24% after pre-treatment of sand filtration with inline coagulation and 22% after pre-treatment of dual media filtration (sand and anthracite), respectively. MFI and SDI also indicated that deep bed filtration with in-line flocculation was better pre-treatment than flocculation alone. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510 -1180 Da), while the small molecular weights (less than 530 Da) were not removed.

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“…The MFI is determined from the gradient of the general cake filtration equation at constant pressure by plotting t/V versus V [6]. …”

Section: Sdi and Mfimentioning

confidence: 99%

Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution

et al. 2010

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“…(c -1) in Appendix) is proportional to the concentration of colloidal substances when the sample temperature is constant 6) . In addition, the MFI-UF value obtained with this method has been reported to correlate with the reduction in flux of RO and NF membranes 7) . However, measurements with this method require a long filtration time and the high cost of the UF filter modules used for measurements.…”

Section: Introductionmentioning

confidence: 97%

Evaluation of Water Quality Using a Plugging Coefficient Based on a Pore Blocking Filtration Model in the Membrane Filtration Process

2008

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We propose a new method to measure the fouling potential of feed water in the membrane separation processes.This method is using the plugging coefficient (K) in four kinds of pore blocking filtration models including the cake filtration model with clear theoretical background as values for water quality evaluation alternative to SDI（Silt Density Index) which is commonly used to assess the fouling potential in the membrane separation processes. We

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“…The MFI can be used to predict the fouling potential of the feed in membrane systems and assumes that the particulate fouling of membranes is dominated by cake filtration. The MFI is determined from the gradient of the general cake filtration equation for constant pressure in a plot of t/V versus V [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…Fouling in crossflow systems is therefore, predominantly due to the deposition of the smaller particles. SDI and MFI therefore, have been criticized for their lack of fundamental basis and the assumption of a relationship between a microfilter (used in SDI and MFI tests) and reverse osmosis membrane [11][12][13]. The contrasting features of SDI, MFI and RO systems are highlighted in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Effect of pre-treatment on fouling propensity of feed as depicted by the modified fouling index (MFI) and cross-flow sampler–modified fouling index (CFS–MFI)

et al. 2009

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The effectiveness of different pretreatment on the fouling propensity of the feed was studied using synthetic waste water. The fouling potential of the feed was characterized by standard modified fouling index (MFI) and cross-flow sampler modified fouling index (CFS-MFI).In CFS-MFI, a cross-flow sampler was used to simulate the condition of a cross-flow filtration. The results indicated that the pretreatment such as flocculation with an optimum dose of 68 mg/l FeCl 3 substantially reduced the fouling propensity of the feed. The standard MFI of flocculated wastewater was reduced by around 99% compared to that of the untreated waste water. Similarly, the adsorption with powdered activated carbon (PAC) of 1 g/l reduced the standard MFI value to more than 99 % compared to that of the untreated waste water. The CFS-MFI values were lower than the standard MFI values for both treated and untreated waste water suggesting that the standard MFI was overestimated. The over estimation of the standard MFI compared to that of the CFS-MFI value was more than 99%.The effect of molecular weight distribution (MWD) of the foulants in the wastewater on the fouling propensity of the feed was investigated. The MWD was correlated with the MFI and CFS-MFI indices. It yielded useful insights in understanding the effect of MW on MFI and CFS-MFI and fouling propensity of the feed.

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Monitoring particulate fouling in membrane systems

Cited by 97 publications

References 4 publications

Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution

Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution

Evaluation of Water Quality Using a Plugging Coefficient Based on a Pore Blocking Filtration Model in the Membrane Filtration Process

Effect of pre-treatment on fouling propensity of feed as depicted by the modified fouling index (MFI) and cross-flow sampler–modified fouling index (CFS–MFI)

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