| 摘要: | 本研究為改善水平流潛流式人工濕地(Horizontal subsurface flow constructed wetland；HSSF CW)因傳統濕地因傳氧效率不佳所衍生的低污染處理效率缺失，規劃曝氣提升各污染物之處理效能，並利用元素鐵厭氣氧化觸發自營性脫硝作用以提升含氮污染物處理效能。藉由設置實驗組(HSSF-G)與對照組(HSSF-F)二系統的水質淨化較能比較，藉此探討本研究所設計曝氣與元素鐵厭氣氧化對HSSF CW污染處理效能特性之影響，相關實驗設施地點位於嘉南藥理大學之生態池區域。系統污染處理效能的評估主要是藉由生化需氧量(Biochemical oxygen demand；BOD)、總氨氮(Total ammonia-nitrogen；TAN)、亞硝酸鹽氮(Nitrite-nitrogen；NO2─-N)、硝酸鹽氮(nitrate-nitrogen；NO3─-N)、總凱氏氮(Total kjeldahl nitrogen；TKN)、總氮(Total nitrogen；TN)、總磷(Total phosphorous；TP)、亞鐵(Ferrous iron；Fe2+)、總鐵(Total iron；TFe)等水質指標來進行，以下結果謹對本研究的重要成果簡述之。據本研究結果可得知，對照組(HSSF-F)與實驗組(HSSF-G)系統在一、二試程的BOD去除效能皆有顯著差異，在第一試程HSSF-F系統的BOD達71.5%，而HSSF-G系統之連續曝氣則將BOD去除提高至91.3%。而第二試程HSSF-G置入元素鐵厭氣氧化設施，其BOD去除率仍維持93.6 %之高去除率，而對照組僅為63.7%。可知曝氣與元素鐵厭氣氧化不但不會造成有機污染的降解形成負面影響，可能對於污染物去除有益。而HSSF-F及HSSF-G系統在NH3-N與TKN的去除效能變化特性相似。從研究結果顯示，在第一試程中HSSF-G系統NH3-N去除率為77.7 %略低於HSSF-F系統86.1%，其顯著性不高。而在第二試程加入元素鐵厭氣氧化後，HSSF-G系統在NH3-N去除效率提升至87.1%與對照86.6%並無顯著差異。而在TKN去除效率變化特性與NH3-N類似，亦即HSSF-G第一試程時TKN的去除率達72.1%，略低於HSSF-F系統83.1%，而HSSF-G在加入元素鐵厭氣氧化時，第二試程的TKN去除率提升至81%，與HSSF-F系統的80.6%相近。從本研究得知TN在HSSF-G系統去除率約63.7%，顯著低於HSSF-F的82.8%，而在加入元素鐵厭氣氧化設施的第二試程，HSSF-G的TN去除率略增為69.5%，仍明顯低於對照組的78.2 %，此一現象的起因係源於TKN與NO3─-N的去除效能不佳所致，之所以會形成此類現象的原因推測可能有機碳源的競爭有關。然而TP在HSSF-F系統及HSSF-G系統試程中的去除率有顯著差異，HSSF-G在二試程去除較率皆較差，而加入元素鐵厭氣氧化設施未能顯著提升TP的去除，其原因是亞鐵與磷酸之沉澱反應最佳pH需發生在8左右，而本系統pH值範圍介於6.58~7.06之間，不屬於此反應較佳的pH範圍，因此鐵氧化產生亞鐵離子對磷的去除效果較不明顯。
To improve the low efficiencies of pollutant degradation induced by lacking of sufficient oxygen transportation, there were two modifications of the artificial aeration and nitrate-dependent anaerobic ferrous oxidation (NAFO) was installed in a horizontal subsurface flow (HSSF) constructed wetland (CW). In the campus of Chia-Nan University of pharmacy and science, there were 2 systems established in this study which included an experimental system and a control one with identical dimension. The former (HSSF-H) installed those modifications while the other (HSSF-F) was regarded as a control system which only possessed a gravel bed and the aquatic plant (Hydrocotyle verticillata Thunb.). In the stage I of the experimental program, there only installed an artificial aeration in HSSF-G and the NAFO device added to HSSF-G in the stage II. The water quality parameters; biochemical oxygen demand (BOD), ammonia-nitrogen (ammonia-nitrogen; NH3-N), nitrate-nitrogen, nitrite- nitrogen, total Kjeldahl nitrogen (TKN), total nitrogen (TN), total Phosphorus (TP), ferrous iron (Fe2+), and total iron (TFe) were used to evaluate the removal efficiencies of HSSF-H and HSSF-F. The conclusions obtained in this study was described in the following.According the experimental results, there was significant differences between the BOD removal ratios of HSSF-G and HSSF-F. In the stage I, the removal ratios of HSSF-G and HSSF-F were 91.3 % and 71.5 %, respectively. When the NAFO device activated in the stage II, the removal ratios of HSSF-G maintained at 93.6 % and that of HSSF-F was 63.7 %. It implied that the aeration could effectively improve the BOD removal performance and the NAFO device played no negative role in the BOD removal process.It also found a similarity between the removal tendencies of NH3-N and TKN in HSSF-F and HSSF-G. In the stage I, the removal ratio of NH3-N in HSSF-G, 77.7%, was not significantly different from that in HSSF-F, 86.1%. As for the stage II, the removal ratios of NH3-N were 87.1 % and 86.6 %, respectively. No significant difference existed between these removal ratios of NH3-N. Similar tendency also occurred in the removal of TKN. In the stage I, a lower removal ratio of TKN in HSSF-G, 72.1 %, still observed and a higher one, 83.1 %, without significant difference from that of HSSF-G resulted in in HSSF-F. When coming to stage II, the removal ratios of TKN in HSSF-G and HSSF-F, 81.0% and 80.6%, were quit close to each other.As for the removal of TN in the stage I, they were 63.7 % and 82.8 % for HSSF-G and HSSF-F, respectively. In the stage II, those removal ratios became 69.5 % and 78.2 %, respectively. A lower removal ratio of HSSF-G mainly resulted from the lower removal ratio of TKN and NO3─-N which might be induced by the competition of organic carbon source. There observed a significant difference between the TP removals of HSSF-G and HSSF-F. No effective improvement of TP removal was activated by NAFO process. It was because that the suitable pH for the sedimentation of ferric phosphate was about 8 while the pH in HSSF-G ranges from 6.58 to 7.06. It was not a proper pH for the sedimentation of ferric phosphate. |
