Effects of super-powdered activated carbon pretreatment on coagulation and trans-membrane pressure buildup during microfiltration

Matsui, Yoshihiko; Hasegawa, Hiroki; Ohno, Kohei; Matsushita, Taku; Mima, Satoru; Kawase, Yuji; Aizawa, Tomoyasu

doi:10.1016/j.watres.2009.08.021

Cited by 64 publications

(23 citation statements)

References 42 publications

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“…With aeration, the PAC particle sizes not only were reduced but also broke particles coming into reactors R2 and R3 and these two reactors had less fouling, which indicates that the presence of PAC lessened smaller particle enhanced fouling and created higher porous cake layers on the membrane surfaces during filtration (R1 vs. R2 and R3), therefore, reduced the TMP [19,30]. Although the porosity of the cake formed on the MF surfaces in three reactors was not measured in this study, our speculations here are supported by Madaeni [44], who observed variable porosities inside cakes on MF membrane using wide ranges of particle sizes and correlated the flux decline.…”

Section: Changes In Particle Size Distributionmentioning

confidence: 99%

Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system

Khan

Takizawa

Lewandowski

et al. 2011

Journal of Membrane Science

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a b s t r a c tTo quantify the effect of dynamic particle size changes and degradation and accumulation of suspended solids (SS) in influents to reactors on membrane fouling frequency in hybrid powder-activated carbon (PAC)-microfiltration (MF) reactors, we operated a PAC-MF system (hollow-fiber module) for more than five months to purify river water before and after pretreatment by a biofilter. The transmembrane pressure, backwashing pressure, resistance to filtration, and SS accumulation and degradation during these dynamic changes were evaluated. The initial dose of PAC was 40 g/L of the reactor and no additional PAC was added during this continuous operational period. The presence of PAC reduced the membrane resistance to filtration even at the end of filtration period when the number of particles in the smallest range (>1.0-3.6 m) was the highest measured by the flow cytometer and microscopy image analysis. This resistance was reduced further when the river water was biofiltered prior to membrane filtration. This real-time study demonstrates that over time PAC and other particles coming into the reactors through the influents degrade and/or become smaller because of the turbulence caused by continuous aeration below the MF membrane fibers. The number of particles in the reactors with diameters less than 10 m increased with time, increasing the fouling frequency; however, the presence of PAC further reduced the particle enhanced fouling. The presence of PAC also increased SS degradation by up to 10%. The increased number of bacteria inside the PAC-MF systems did not contribute to the number of membrane fouling. Even though the particle sizes inside the reactors became smaller with time, the gradual increase in net accumulation of SS was also an important factor controlling the performance of the PAC-MF system.Published by Elsevier B.V.

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Section: Changes In Particle Size Distributionmentioning

confidence: 99%

Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system

Khan

Takizawa

Lewandowski

et al. 2011

Journal of Membrane Science

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“…Alternatively, some authors have recognized the potential benefits of a combined coagulation and PAC adsorption process before membrane filtration [33]; however, in these cases the membrane operation process lasted for only 30 min [12], or less than 5 h [17]. Matsui et al [34] found that both physically reversible and irreversible membrane fouling were reduced by a combination of PAC and polyaluminum chloride (PACl) pretreatment, because of a high NOM removal and the formation of larger and more porous flocs. Dialynas and Diamadopoulos [35] found that after the addition of PAC to a coagulation-UF system, the trans-membrane pressure increased rapidly due to the formation of the PAC cake on the membrane surface, but there was a high degree of organic matter removal.…”

Section: Introductionmentioning

confidence: 99%

Investigation of pre-coagulation and powder activate carbon adsorption on ultrafiltration membrane fouling

et al. 2014

Journal of Membrane Science

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a b s t r a c tPre-coagulation by alum before ultrafiltration without (CUF) and with (CAUF) powdered activated carbon (PAC) addition was investigated to explore the influence of PAC on membrane fouling. It was found that the continuous addition of a low dosage of PAC reduced membrane fouling for operational run periods o20 days, both for reversible and for irreversible components of fouling. The presence of PAC increased the removal of dissolved organic matter (DOM), particularly proteinaceous substances, and some fractions of humic-type substances. For a longer operation time (420 days) an increase in mainly reversible fouling was evident and was attributed to microorganism growth in the cake layer, as indicated by the enhanced concentrations of extracellular polymeric substances, such as polysaccharides and proteins. A process of crystallization of the coagulant floc in the cake layer with increasing operation time was believed to cause desorption of DOM from primary coagulation particles and a decrease in their size, and consequently a higher density of cake layer. PAC absorption of desorbed DOM within the cake layer, and residual DOM after coagulation, reduced DOM reaching the membrane surface and the extent of subsequent internal membrane fouling.Crown

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“…After five experimental runs with the laboratory-scale experimental setup, an automatic hydraulic backwash system was introduced to the MF step; the MF was performed at a normal filtration flux (6.25 cm/h), and the MF membrane was hydraulically cleaned by backwash at a pressure of 500 kPa for 10 seconds every 2 h [9].…”

Section: Laboratory-scale Experimentsmentioning

confidence: 99%

NF membrane fouling by aluminum and iron coagulant residuals after coagulation–MF pretreatment

et al. 2010

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The effects of coagulant residuals on fouling of a nanofiltration (NF) membrane were investigated. Experiments were carried out with a laboratory-scale microfiltration (MF)-NF setup and a pilot MF-NF plant. In the laboratory-scale experiments, NF feed water was pretreated with poly-aluminum chloride (PACl) or alum followed by MF. NF membrane permeability declined when the feed water contained residual aluminum at 18 µg/L or more, but not when it was lower than 9 µg/L. When pretreated with ferric chloride, no substantial decline of NF membrane permeability was observed; residual iron did not affect the permeability. When SiO2 was added to the water before the pretreatment with PACl, the NF membrane permeability declined at about double the speed. Thermodynamic calculations and elemental analysis of foulants recovered from the membranes indicated that the majority of inorganic foulants were compounds composed of aluminum, silicate, and possibly potassium. In the pilot plant, NF feed was pretreated by PACl. Transmembrane pressure for NF doubled over 4.5 months of operation. Although the aluminum concentration in the NF feed was not high (30 µg/L), analysis of membrane foulants revealed excessive accumulation of aluminum and silicate, also suggesting that aluminum residuals caused the membrane fouling by alumino-silicates or aluminum hydroxide.2

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Effects of super-powdered activated carbon pretreatment on coagulation and trans-membrane pressure buildup during microfiltration

Abstract: As a pretreatment for membrane microfiltration (MF)

Cited by 64 publications

References 42 publications

Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system

Membrane fouling due to dynamic particle size changes in the aerated hybrid PAC–MF system

Investigation of pre-coagulation and powder activate carbon adsorption on ultrafiltration membrane fouling

NF membrane fouling by aluminum and iron coagulant residuals after coagulation–MF pretreatment

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