| 摘要: | 台南地區因原水水質pH偏鹼，在使用鋁鹽混凝劑後易產生水中殘餘鋁偏高，本研究之重點在於探討，是否會因有機物如腐植質存在，而增加溶解性鋁殘留，及對調降pH值為改善方案之淨水場，評估有機物存在對溶解性鋁殘留超出內控值之潛能。試驗原水以合成配製添加有機物方式進行硫酸鋁混凝瓶杯試驗，對原水及混凝後上澄液分析濁度、pH、UV254、溶解性鋁等水質參數，另以螢光激發/發散陣列光譜儀(Excitation/Emission Fluorescence Matrix Spectrofluorometer, EEFMs)分析有機物螢光特徵之波峰位置，觀察有機物與水中殘餘鋁之間相關性。結果顯示pH值高之原水使用硫酸鋁混凝劑易產生高濃?溶解性鋁殘留，尤其有機物(HA、FA)存在時影響加劇，調降pH值可明顯減少殘餘溶解性鋁濃?。在本研究中，調降pH 至7時，腐植質存在仍有可能使其超出0.16 mg/L之潛能，所以有高腐植質之原水，應先設法降低腐植質亦可降低殘餘溶解性鋁濃?。我們評估以實場操作模式，發現調降pH值至7時，如硫酸鋁劑量添加不足所造成殘餘鋁超出0.16 mg/L之潛能較高。由EEFM圖譜之激發/發射波長顯著位移及Stern-Volmer方程式斜率兩者評估後顯示腐植質與鋁易發生錯合現象。
The high alkalinity of raw water in Tainan area may cause the high residual aluminum after adding aluminum salts coagulant. In this study, we investigated the effect of the organics (humic substances, filvic acid) on the increasement of residual dissolved aluminum. And then, we assessed the risk whether the existence of the organics would cause the level of residual dissolved aluminum out of internal control for the water purification plants with the improvement by decreasing pH. In the experiment, we conducted the aluminum sulfate coagulation jar test by adding organic matter to prepare the synthetic raw water. Then, we analyze the water quality parameters include turbidity, pH, UV254, and soluble aluminum level, of raw water and supernatant liquid after sedimentation. In addition, we also analyzed the peak position of the fluorescent organics and to observe the relationship between the organic and residual aluminum in water by Excitation/Emission Fluorescence Matrix Spectrofluorometer (EEFMs).We found that adding aluminum sulfate coagulant into the raw water with high pH is easy to induce high residual dissolved aluminum, especially with existence of organics (HA, FA). On the other hand, lower the pH can significantly reduce the residual dissolved aluminum. In this study, even if the pH has been lowered to 7, the existence of the humic substance may still make the concentration exceed 0.16 mg/L. As a result, for the raw water with high humic substance, it should be lowered the level of humic substance so that the residual aluminum will be reduced. We evaluate the operating mode in practice, as pH being declined to 7, the insufficient of aluminum sulfate will contribute to the Potential of increasing residual aluminum. By evaluating the excitation / emission wavelengths significant shift and Stern-Volmer equation slope assessment after coagulation by the EEFM, it showed that humic substances and aluminum would form complex reaction. |
