Modeling Performance and Assessing Mechanisms NOMs Removal by Ozonation Coupled with Biological Activated Carbon Processes

• Main Authors: Chung-Huei Liang, 梁仲暉
• Other Authors: Pen-Chi Chiang
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/73959231052627568536

博士 === 國立臺灣大學 === 環境工程學研究所 === 94 === This research was focused on developing a non-steady-state numerical model to differentiate the adsorption and biodegradation quantities of a biological activated carbon (BAC) column. The mechanisms considered in this model included adsorption, biodegradation, convection and diffusion. The performance of adsorption and biodegradation on the BAC column was studied using continuous columns tests. Simulations were performed to evaluate the effects of some parameters such as packing media size and superficial velocity on adsorption and biodegradation performances for the removal of dissolved organic matter from water. The experimental results show that before breakthrough, adsorption should be the prevailing mechanism for removal the p-hydroxybenzoic acid, and biodegradation should be responsible for reducing the ozonation intermediates. EBCT could influence the performance of both adsorption and biodegradation in extent. Increasing EBCTs could make the equilibrium more complete for adsorption, thereby improving the performance. The ratio of adsorption to biodegradation on the BAC column increased as EBCT increased, and this implied that adsorption was dominant in an equilibrium condition. Also, the bioactivity approach of BAC can not only reveal the importance of biodegradation mechanisms for the intermediates of ozonation, but also quantify the extent of the adsorption or biodegradation reaction occurring on BAC. This model achieves a good approximation of the experimental data by adjusting the liquid-film mass transfer coefficients. Liquid-film mass transfer coefficient has a certain correlation to the Stanton number. The Freundlich isotherm exponential term and the maximum specific substrate utilization rate from Monod kinetics and the diffusion coefficient are the most sensitive variables, which provides important information to control the performance of the BAC. Decreasing particle size can improve the overall removal efficiency, especially for adsorption rather than biodegradation. Meanwhile, a lower Damköhler number permits more substrate passes the biofilm to the adsorbent and makes the adsorption ratio increase.