Thesis Archive
EVALUATION OF DRAW SOLUTIONS FOR FORWARD OSMOSIS USING A SODIUM ALGINATE-BACTERIAL CELLULOSE MEMBRANE FOR WATER RECOVERY
Alyssa Mae C. Acyatan
Czarielle Audrey G. Lim
Abstract:
Forward osmosis (FO) is an emerging membrane technology that may soon compete with industrial membrane separation processes. Its main driving force comes from the osmotic pressure difference between the feed and draw solutions which allows water to be recovered by flowing towards the draw solution through the semi-permeable membrane. Many studies have focused on fabricating a suitable membrane for the process, however there are still a number of problems concerning FO that should be addressed to improve its performance. A noticeable problem would be the lack of studies concerning draw solutions in FO which is an important factor in the process since the main driving force is dependent on the osmotic pressure of this solution with the feed. Thus, determining a compatible draw solute used for forward osmosis is crucial in enhancing its performance. Thus, important factors such as the types of draw solutions and their operating conditions are taken into consideration in this study. Three factors were looked into to attain an optimal value of the response variable, normalized water flux, which are the osmotic pressure of the draw solution, flow rate of both solutions, and the draw solute. The three selected solutes NaCl, MgCl2, and fructose were investigated as draw solutions with simulated dirty water as the feed solution using the alginate-bacterial cellulose (BCA) membrane. The osmotic pressures of these draw solutions were varied to 40, 55, and 70 bar and at flow rates of 200, 250, and 300 mL/min to determine which solute and operating conditions were most suitable in performing FO to recover water. Based on the data obtained from the experiment, the normalized water flux for each run was calculated then optimized through central composite design (CCD) using Design Expert 7.0.0. The optimal solute was determined to be fructose with operating conditions at an osmotic pressure of 70 bar and a flow rate of 300 mL/min. The normalized water flux given these optimal conditions is predicted to be 1.437 LMH∙mm with a desirability of 0.768.
Adviser:
BELTRAN, Arnel B.