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Removal of natural organic matter for drinking water treatment using electrocoagulation and ultrafiltration Froese, Emily

Abstract

This work combined iron electrocoagulation (EC) and ultrafiltration (UF) to treat synthetic and natural surface waters to remove Natural Organic Matter (NOM). Fixed EC conditions were applied to the feed water in a continuous flow EC reactor, at a flow rate of 1 LPM and an applied current of 2 A. These test conditions resulted in an average DOC and UVA-254 reduction of 33+/-4% and 57+/-8% respectively for the synthetic feed water. The EC effluent acted as the feed water for the EC/UF systems. Two UF membrane types were tested: (1) a 300kDa ceramic disk membrane; and, (2) a 0.04 um PVDF hollow-fibre membrane. Both systems were operated at a constant flux of 50 LMH. Periodic backwash cycles were applied to evaluate the effect of backwashing on the overall membrane fouling rates. Backwashing with a 30 minute filtration cycle and 5 minute backwash reduced the fouling rate by (50+/-3)% and (2+/-6)% in the ceramic and PVDF membranes, respectively. Applying backwash to the EC/UF test with natural feed water resulted in a (95+/-0.5)% lower fouling rate compared to the EC/UF test with synthetic feed water test under the same conditions. Therefore, water composition has a significant effect on the membrane fouling rates of the EC/UF system. Air sparging was also applied to the PVDF membrane system and resulted in reducing the overall fouling rate by (64+/-2)%. Comparatively, the combination of air sparging and backwashing reduced the overall fouling rate by (98+/-1)%. The EC/UF test with air sparging and backwash also resulted in additional NOM removal of the UF permeate. Air sparging has never been combined with an EC/UF system and these are promising results in the quest to develop a EC/UF drinking water treatment system for small and remote communities.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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