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Characterization of Ultrafiltration Membranes and Effect of Biofouling on Their Water Treatment Performance

Abstract Details

2011, Doctor of Philosophy in Engineering, University of Toledo, College of Engineering.

To address drinking water quality concerns, membrane separation technologies have been developed, resulting in the continuous reduction of their cost and rapid extension of their application possibilities. Despite the remarkable advantages of membrane separation technologies, the drastic reduction of water flow due to membrane fouling and the high cost of membrane replacement pose a significant problem in water separation applications.

This research investigated the impact of feed water characteristics (i.e., conductivity and pH), conditioning layer formed on biofilms, and presence and activity level of a biofoulant on the membrane-solute interaction forces (i.e. hydrophobic attraction) and membrane morphology. Experiments were performed on cellulose acetate ultrafiltration (CAUF) membranes (MWCO 20,000 D) in crossflow filtration for up to 53 hours. Fouled membrane characterization from the macro- to nano-scale was effectively carried out using existing and emerging techniques including fluorescence microscopy for cell activity, image analysis for biofilm surface coverage and intensity, ATR-FTIR for biofilm chemical composition, AFM for fouled membrane surface roughness and skewness, and CFM for its relationship to adhesion forces.

As the feed water conductivity increased and the membrane surface roughness increased, the magnitude and range of the adhesion force increased and, subsequently, the permeate flux decline increased suggesting that feed water chemistry impacted membrane potential for fouling. Comprehensive biofilm characterization, specifically AFM, revealed that bacterial cells deposited, and then formed a consolidated biofilm, on the low shear rate areas of the membrane surface. And, as expected, the rate of biofilm formation was higher in the presence of a carbon source and active cells. Additional experiments were carried out to determine the contribution of abiotic fouling (conditioning layer) to cell activity and built up resistance on CAUF membranes. Regardless the degree of abiotic fouling, biotic fouling contributed most significantly to permeate flux decline. However, in the presence of active cells, abiotic fouling supported biotic fouling, by acting as a food source.

This research used and modified emerging biofilm characterization techniques to better understand the causes of biofilm formation and its impact on the water filtration performance of CAUF membranes given varied feed water characteristics.

Cyndee Gruden (Committee Chair)
Isabel Escobar (Committee Member)
Ashok Kumar (Committee Member)
Defne Apul (Committee Member)
Youngwoo Seo (Committee Member)
106 p.

Recommended Citations

Citations

  • Zaky, A. M. (2011). Characterization of Ultrafiltration Membranes and Effect of Biofouling on Their Water Treatment Performance [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1294331612

    APA Style (7th edition)

  • Zaky, Amr. Characterization of Ultrafiltration Membranes and Effect of Biofouling on Their Water Treatment Performance. 2011. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1294331612.

    MLA Style (8th edition)

  • Zaky, Amr. "Characterization of Ultrafiltration Membranes and Effect of Biofouling on Their Water Treatment Performance." Doctoral dissertation, University of Toledo, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1294331612

    Chicago Manual of Style (17th edition)