| 摘要: | 本研究以掃流過濾進行海水淡化之前處理，使用多孔性粉末狀活性碳(PAC)附著在薄膜表面上，形成適當厚度的動態膜，利用其攔截與吸附能力，期望能將海水中之微生物與有機物質有效的去除，減少後續薄膜程序中薄膜結垢的發生。
首先針對PAC之吸附性能進行分析，結果顯示Freundlich isotherm是比較適合的等溫吸附模式。在模擬海水的掃流過濾實驗中，可以發現過濾阻力之來源主要為海水中之有機物及微生物附著在濾膜上所造成。因此，藉由結合PAC與海水之掃流過濾系統，當動態膜形成後，活性碳會吸附與分解海水中的有機物及微生物，水質淨化結果可從懸浮液端與濾液端的濃度、濁度、化學需氧量(COD)及溶解有機碳(DOC)進行分析。結果顯示：海水的腐質酸濃度與濁度藉由PAC動態膜過濾後皆下降至0，而COD及DOC值分別下降約67%及92%，表示在濾膜上生成的動態膜對海水中汙染物進行吸附與攔截，可以達到海水淡化前處理之效果。除了COD值，其餘指標皆達RO進水之標準，由於COD值會受還原性物質影響。
隨著動態膜厚度的增加，其汙染物的貫穿時間也隨之增加，由此可知PAC動態膜厚度越厚其達吸附平衡的時間越長，可以操作更長時間。由實驗得知最佳操作條件在掃流速度為0.3m/s、過濾壓差為100kPa且動態膜厚度為0.31公分，會有較高的濾速，其DOC去除效率可達92 %，且其達吸附平衡的時間亦愈久。由理論計算結果得知，在高過濾壓差及低掃流速度下是最有效提升整體膜過濾系統之效益，因此選擇在高過濾壓差及低掃流速度下，能使濾速較快且活性碳吸附達平衡的時間較長。
In this study, the cross-flow microfiltration in the pretreatment of seawater desalination. Using the porous powdered activated carbon (PAC) attached to the membrane surface, forming a dynamic membrane of appropriate thickness, the use of the interception and adsorption capacity, can effectively remove organic materials and microbes in the seawater to reduce the subsequent membrane fouling occurs.
First, the analysis for the adsorption capacity of PAC showed that Freundlich isotherm is more suitable for the adsorption isotherm model. In the artificial seawater cross-flow filtration experiments, filtration resistance sources can be found in seawater composition of organic matter and microbes attached to the membrane caused. Thus, by combining the PAC and seawater filtration systems, when the dynamic membrane formation, which carbon will adsorption and decomposition organic matter and microbes in seawater, the effluent quality from the filtrate side, concentration of organic, turbidity, chemical oxygen demand (COD) and dissolved organic carbon (DOC) for analysis. The results showed that the concentration and turbidity of seawater by the PAC dynamic membrane filtration are down to zero, and COD and DOC values decreased by about 67% and 92%, respectively, indicating that the dynamic membrane adsorption and interception of pollutants in seawater , you can reach the desalination the effect of pre-treatment. In addition to the COD value, the other indexes are up to standard water of the RO, because the COD value will be affected by the impact of reducing substances.
With the increase of dynamic membrane thickness, it also increases breakthrough time, it can be seen dynamic membrane thickness thicker its reach adsorption equilibrium time longer. From the experimental results, the optimum operating conditions in the cross-flow velocity of 0.3 m/s, filtration pressure is 100 kPa and dynamic membrane thickness of 0.31 cm, there will be a higher filtration rate, which DOC removal efficiency of up to 92%, and its reach adsorption equilibrium time also the longer. Calculated from the theoretical results that, at high pressure and low cross-flow velocity is the most effective to enhance the effectiveness of the overall membrane filtration system, so choose under high pressure and low cross-flow velocity, enabling faster filtration rate and activated carbon adsorption reached equilibrium time longer. |
