應用固定生物法進行廢污水除氮研究

Abstract

固定化生物法在廢水處理上有許多優點，包括易於製備、菌體穩定而不易失去活性、結合強度佳、污泥體積小、操作簡單及操作費用低等優點。因而本研究以採用生活污水廠之活性污泥並以三醋酸纖維素(cellulose triacetate)包覆，並製作成固定化生物粒，以做為處理生活污水及液晶面板製程廢水，同時評估碳、氮之去除效率對於水力停留時間(hydraulic retention time，HRT)及曝氣比值(aeration ratio)對處理效率的影響。 本研究有A廠跟B廠兩組實驗，A廠以生活污水處理廠調節池原水做為實驗之進流水，而B廠則以液晶面板製造廠之製程廢水為進流水。A廠的實驗分成三個階段進行，第一階段先以原水為進流水，第二階段以原進流水並添加合成廢水(COD為300 mg/L)，而第三階段則以原進流水並添加碳酸鈣及甲醇化作為試驗。B廠實驗也是分為三個階段，全程使用廠內廢水處理單元之進流水為實驗處理原水。 實驗操作時，先以24hrs HRT進行，待穩定後再以不同HRT(12、9及6 hrs)和不同曝氣比值(連續曝氣、1ON:1OFF、1 ON:2 OFF、2 ON:1 OFF及2 ON:2 OFF)為操作條件觀察固定生物粒之處理效率。 結果顯示，在HRT為12 hrs的操作下， COD去除率(90%)最穩定；而以相同的HRT下進行，當曝氣比值A廠以1 ON:2 OFF 及B廠以2 ON:1 OFF 的操作時，則分別有86%(有添加甲醇)及40%的總氮(total nitrogen, TN)的去除率。

Biological cell entrapment technique has many advantages in the application of wastewater treatment include simple preparation, low effluent suspended solid content, better mechanical strength and low operation cost. In this study, the bio-carriers were prepared by using cellulose triacetate to entrapped aerobic sludge obtained from domestic wastewater treatment plant, domestic and Thin Film Transistor Liquid Crystal Display (TFT-LCD) industry wastewater treated with bio-carriers. Therefore, this research attempts to investigate the removal efficiency of carbon and nitrogen of application of the cell entrapment technique with different hydraulic retention time (HRT) and aeration ration. In this study, two sets of experiment were carried out for the examination of system performance. Set A use influent from domestic wastewater treatment plant and Set B use influent from TFT-LCD industry’s wastewater treatment plant, each set of experiment has three stages of test. In set A experiment, raw wastewater was used as the influent, synthetic wastewater was added with raw wastewater in stage two, calcium carbonate and methanol were added in stage three combined with raw wastewater. Site B use raw wastewater as influent during three stages of test. In order to explore the nitrogen removal efficiency of the bio-carriers, both sets of experiment were operated at different HRT (12, 9 and 6 hrs) and aeration ratio (1ON:1OFF, 1 ON:2 OFF, 2 ON:1 OFF and 2 ON:2 OFF). The results shows that the biological cell-entrapment technique at HRT 12hrs and intermitted aeration of 1 ON:2 OFF and 2 ON:1 OFF could remove COD effectively (90%) and the highest removal efficiencies of nitrogen when adding and without adding methanol were 86% and 40%, respectively.