Fouling characteristics of microfiltration membranes by organic and inorganic matter and evaluation of flux recovery by chemical cleaning

Publication Type:
Journal Article
Desalination and Water Treatment, 2014, 52 (37-39), pp. 6920 - 6929
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© 2013, © 2013 Balaban Desalination Publications. All rights reserved. Abstract: Characteristics of membrane fouling by organic and inorganic foulants and flux recovery by chemical cleaning were investigated in this study. Three kinds of raw water with organic matter (15 mg/L humic acid), with inorganic matter (1 mg/L Fe and 1 mg/L Mn) and a mixture of organic and inorganic matter (humic acid, Fe and Mn) were tested. The effects of Ca 2+ and pH on fouling were also investigated as well as efficiency of chemical cleaning. The results showed that raw water with the mixture reduced the final flux by 10%. On the other hand, the final fluxes were reduced by 8% for inorganic matter and by 78% for organic matter. Although, FI decreased with the existence of Ca 2+ in the mixture of humic acid, Fe and Mn, flux was recovered easily by backwashing because Ca formed a cake layer by chelating with humic substances. However, pre-treatment with sodium hypochlorite reduced the flux severely for raw water containing inorganic matter. Acid (2% nitric acid) and base (1% sodium hydroxide), were used to clean the fouled membranes. Cleaning efficiency was different by changing the cleaning sequence of the two chemicals (acid/base and base/acid). Flux recovery was 20% higher in base/acid sequence. These results showed that both raw water characteristics and cleaning method should be thoroughly investigated for appropriate operation of membrane processes.
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