Dissertation submitted in compliance with the requirements of the Master's Degree in Technology : Biotechnology, Technikon Natal, Durban, 2001. / A woven fibre membrane unit was developed locally and used for this study. The membrane unit was submerged in the aerobic tank of an anoxic-aerobic biological treatment process to treat dairy effluent. Another unit similar to the process above was also set up but with a gravity settling tank replacing the membrane unit. Kinetic studies were done on both processes and their results compared. Effluent characteristics of both processes were also compared. For the membrane bioreactor, the effectiveness of two backflush methods ie air and water, were tested. In this study it was discovered that air backflush could remove the clogging formed at external and internal pores of the membrane better than water backflush measured in terms of rate of pressure recovery and energy consumption. The effluent quality of the membrane bioreactor (MBR) in terms of COD, nitrogen, suspended solids and turbidity was excellent under all conditions tested and was better than conventional activated sludge system. The COD removed based on the average value in MBR was 96.02 % compared to 94 % conventional system. A mass balance of the processes showed that 79 % in the form of nitrogen fed into both the MBR and conventional systems was denitrified. The effluent suspended solids from the MBR was not determinable while that of conventional system was 2.09 mglL. Maximum specific nitrification rate determined graphically was 3.0 d-I and 2.10 d-I in conventional and MBR respectively. The smaller value of nitrification rate in MBR could be attributed to large number of nitrifier volatile suspended solids in the system. The estimated true yield and decay rate coefficients of conventional system is 0.204 kgVSS/kgCOD and 0.013 d-I respectively. The flux obtained from this study is between 22 and 92 L/m2.h. However, the average flux value is 57 L/m2.h for the whole period of operation. Regular flux decline observed during operation was improved through regular backwash with air and chemical cleaning. The transmembrane pressure did not as whole increase more than 55 kPa due to frequent cleaning of the membrane surface. / M

Thesis (Ph.D.)--New Mexico State University, 2007. / Adviser: N. Nirmalakhandan. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, August 2009. / Title from PDF title page (viewed on Aug. 3, 2009). "School of Chemical Engineering and Bioengineering." Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 175-188). Also available in print.

Thesis (MScIng)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on March 18, 2009. Major professor: Ilhami Yildiz, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Agriculture, with specialization in: Agricultural Engineering Technology." "February 2009." Includes bibliographical references (p. 115-122). Also available on microfiche.

No description available.

This study focuses on the optimisation of submerged hollow fibre membrane performance by analysing the role of air sparging on the reduction of membrane fouling. In submerged hollow fibre membranes, rising bubbles have been shown to induce shear, liquid movement and fibre displacement. The interaction between fibre movement induced by bubbling and the microfiltration performance was assessed for various parameters (fibre tightness, fibre length, fibre diameter, air flowrate, nozzle size, and feed concentration). A model feed of yeast suspension and a series of isolated fibres were used. The fibre movement was assessed by monitoring the displacement using video recording. Bubble population parameters were also measured. The results suggest that bubbleinduced fibre movement plays an important role in controlling membrane fouling. Investigations of the critical flux at various operating conditions also supported these conclusions. Since energy consumption for aeration is a major contributor to the cost in submerged membranes, the potential to minimise the aeration cost has been tested by implementing intermittent aeration and different nozzle sizes. It was found that an optimum condition associated with a low fouling rate could be reached by combining various aeration intermittencies and nozzle sizes. An attempt to suppress fouling without aeration was made by incorporating vibrations into a submerged hollow fibre membrane system. The effects of vibration frequency, type of yeast (washed and unwashed) on the filtration performance were observed. The impact of coagulant addition on filtration enhancement was also analysed. The performance of microfiltration was evaluated based on its critical flux value. The findings in this preliminary study indicated potential fouling control by applying vibrations to submerged membranes. A semi-empirical model was developed to predict the filtration behaviour by taking into account the bubble-induced shear and fibre movement. The predicted critical flux values suggested that membrane fouling appears to be more prominent at low air flowrate, with tight fibres, and higher feed concentrations. The model fits the experimental data with discrepancies from approximately 0.3% to 20%. The predicted filtration profiles at different operating modes demonstrate the importance of bubble-induced shear and fibre movement in the improvement of filtration performance.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 207-215).

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 156-168). Also available on the Internet.