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This research studied the effect of resistance-in-series model on Nanofiltration (NF) of combined carbonate species and natural organic matter (NOM) using crossflow nanofiltration (HL4040FN, GE water and process technology). Solution condition was controlled with ionic strength of 0.004, 0.01, 0.05 and 0.1 M Na2CO3, combined with NOM concentration of 10 mg/L. Various solution pHs of pH 4.3 (H2CO3 equiv. pt.), 6.3 (pKa1), 8.3 (HCO3- equiv. pt.), 10.3 (pKa2) and 11.3 (CO32- equiv. pt.) were studied. Experimental results revealed that cake resistance (Rc) showed the highest resistance when compared with other types of resistance (Rg and Ra). Increased ionic strengths caused a lower solution flux, possibly due to an increased concentration at the membrane surface, corresponding to higher resistance value. Increased solution pHs resulted in similar trend with increasing ionic strengths, indicating higher solution flux decline, thus resulting in increased resistance, especially cake resistance.
 Mattaraj, S. 2550. Water chemistry. Ubon Ratchathani University verlag. (in Thai)
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