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Coagulation prior to membrane filtration is widely accepted as a standard hybrid processbecause it allows poorer quality source waters to be used with less fouling. But more must beunderstood about the effect of coagulation conditions on the performance of membranesystem, especially in submerged membrane system. The objectives of this research were toelucidate the relation between coagulation pretreatment and membrane performance andexplore the effect of coagulation pretreatment and microfiltration on GAC post-treatment.Experiments were conducted in pilot scale using a 500 m3/day plant with submergedmicrofilters. Raw water collected from Han River was used as feed water and ploy aluminiumchloride was used as coagulants. Granular activated carbon at EBCT of 15 min was used aspost- treatment of membrane system to control taste and odor in product water. The resultsindicate that the coagulation condition had a significant impact on membrane fouling.Coagulation pretreatment was essential to stabilize transmembrane pressure (TMP) especiallywhen the turbidity of feed water was high. As more organic matter was removed bycoagulation, membranes fouled less. On the other hand, TMP was not sensitive to feedturbidity after coagulation and sedimentation. It appears that not only the removal of particlesand organics but also the characteristics of coagulation flocs affect the membraneperformance and pretreatment efficiency. Based on the experimental results, a technique usingfouling index was suggested to control coagulation process. Coagulation was found toprolong the lifetime of GAC post-treatment by reducing dissolved organic matters up to 60 %. Includes 11 references, table, figures.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 8File Size: 1 file , 420 KB