臭氧配合生物活性碳程序去除自來水中有機物之機制與模式之研究

本論文之重點在於發展非穩定態數學模式，以數值方法定量發生於生物活性碳的吸附以及生物降解兩種機制，所去除有機物之質量與時間變化。在實驗設計上，以連續式管柱試驗來評量生物活性碳管柱中吸附與生物降解之處理效能，並提供模式所需之輸入參數，以做為模式驗證與模擬之用。在模式應用上，本論文嘗試改變部分管柱之操作參數，例如填充介質之粒徑、管柱表面流速等，以模擬吸附與生物降解機制對於溶解性有機物處理效能之影響。實驗結果顯示，在管柱發生貫穿之前，對於高吸附性但低生物降解性的目標污染物對羥基苯甲酸p-hydroxybenzoic acid，去除的機制以吸附為主；而生物降解主要去除其臭氧副產物。另一方面，增加空床接觸時間可使吸附平衡更加完全，進而提升吸附的處理效果；同時，提高空床接觸時間亦會提高吸附對生物降解之比例，此一現象進一步驗證在高空床接觸時間下，吸附乃為主要的去除機制。利用生物活性定量的方法，除可確認生物降解為去除臭氧中間副產物之主要機制之外，還可進一步做為吸附與生物降解定量之用。本模式在適當的質傳係數修正之後，其預測之結果可與實驗結果有良好的一致性；而此一質傳係數與Stanton number之間具有特定之正比例關係。在敏感度分析結果發現，Freundlich等溫吸附線之係數、Monod方程式中的最大反應速率、以及擴散係數等，為模式中影響最為顯著的參數，此一訊息可進一步提供在實際操作上，改善處理效能之依據。降低填充介質顆粒之尺寸，對於吸附有顯著的改善，進而可提升整體的處理效能；在此同時降低Damköhler number可使更多基質穿過生物膜到達活性碳的表面，進而提高了吸附的比例。

關鍵字

吸附；生物降解；生物活性碳；粒狀活性碳；數值模式

並列摘要

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.

並列關鍵字

Adsorption ； Biodegradation ； Biological activated carbon (BAC) ； Granular activated carbon (GAC) ； Numerical model

參考文獻

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4. Andersson, A., Laurent, P., Kihn, A., Prevost, M., Servais, P., 2001. Impact of temperature on nitrification in biological activated carbon (BAC) filters used for drinking water treatment. Wat. Res. 35(12):2923-2931.

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國際替代計量

臭氧配合生物活性碳程序去除自來水中有機物之機制與模式之研究

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