| 摘要: | 本研究在嘉義縣大林鎮慈濟醫院污水處理廠旁約1200m2空地設置人工溼地實驗系統模場，希望能以自然生態淨水的方法，從原來的污水處理廠（二級處理水）再抽取入設計好的人工溼地實驗系統模場做生態處理（三級處理水），企圖能降低放流水中總氮（TN）能達到「農業灌溉用水標準」，和慈濟証嚴法師對水資源儘可能回收再利用環保與節約之目的。
本人工溼地設置時就針對較為實際附合自然環境處理材料與處理技術，以省能源，低成本，及儘可能降低二次污染的考量方法，又可以提供當地生態，景觀，教育等弁遄A在1200m2空地中設計總面積為782 m2人工溼地系統模場，分三單元有FWS溼地面積450 m2和SSF溼地186 m2，最後是接連生態景觀池面積146 m2，每日平均抽取30 m3/d流量污水（二級處理後放流水），相當於水力負荷（hydraulic loading rate）為0.05m/day，這些污水主要是來至大林慈濟醫院醫療及民生用水截入到污水處理廠，抽取到人工溼地實驗系統模場。
早期之操作結果顯示，雖然各項水質當初進流濃度即相當低，但經過人工溼地實驗系統模場之後，仍然有部份會有處理效果。當初在實驗前大林慈濟醫療園污水處理所排放的放流水中，除了總氮（TN）之外，其他各項水質報告均已符合「農業灌溉用水標準」。結果顯示總氮中以硝酸氮濃度最高（28.65mgN/ L），經由人工溼地處理過後，濃度可以降至15.99 mgN/L，去除效率為44％。由於剛開始模場處於啟動「適應期」，未達預期的去除效能，主要原因植物生長剛開始密度不高， 進行脫硝作用所需碳源也較不足。而在FWS溼地與SSF溼地對硝酸氮的去除效能，FWS溼地的硝酸氮去除率為15％，SSF溼地為34％，顯示SSF溼地中的去除效能上比FWS溼地更強。
實驗進行到穩定操作期(I)（半年），調高每日平均流量70m3/d，相當於水力負荷為0.11m/day，結果顯示，硝酸氮由原本進流前37.58mgN/ L，降低至11.98 mgN/ L，去除效能達68％，與其他文獻相同操作條件的溼地硝酸氮去除效能相同。再比較FWS與SSF溼地的硝酸氮的去除速率，FWS溼地硝酸氮去除率為2.48gN/m2/d，SSF的去除速率為3.61gN/m2/d。研究結果顯示，SSF溼地對於硝酸氮的去除效能比FWS溼地較好。在高濃度的硝酸塩及沒有額外碳源添加的進流條件下，無觀察到氨氮及亞硝酸氮在濕地中明顯累積，因此上述硝酸氮在濕地中的去除主要可歸因於微生物脫硝作用。
This study has set up the Artificial Wetland Experimental System Model Field for area about 1200m2 beside the wastewater treatment plant of Dalin Tzu Chi Medical Center, Chiayi Hsien, hoping to pump from the original wastewater treatment plant (secondary treatment water) into the designed artificial wetland experimental system model field for ecological treatment (tertiary treatment) with natural ecological water purification method in an attempt to reduce the total nitrogen amount to the degree of “agricultural irrigation water standard”, also to achieve the goal of environmental protection and reservation for best recycling and reuse of the water resource that Cheng Yen, the founder of Tzu Chi Foundation, intends to do all the time.
At the beginning when this Artificial Wetland Experimental System Model Field was set up, it has practically applied the treatment material and technique that better met natural environmental protection idea to achieve energy saving, low cost and reduce of second time pollution, and to display local ecological, scenic and educational, etc., functions. Of the 1200m2 area, the total designed area for the Artificial Wetland Experimental System Model Field is 782m2, which is divided into three units for FWS wetland area 450 m2, SSF wetland area 186m2, and the rest 146m2 has been connected to ecological scenic pond. The average water pumping is 30m3 of wastewater flow daily (discharged water after second degree treatment), which almost reaches 0.05m/day of the hydraulic loading rate. The discharged wastewater mainly from the medical water of Dalin Tzu Chi Medical Center and daily use water of the households has been loaded into the wastewater treatment plant and then pumped into the Artificial Wetland Experimental System Model Field.
The operation results at the earlier stage indicated that although the water quality of the incoming flow density was very low, however, after going through the Artificial Wetland Experimental System Model Field there was treatment result partially. Of the discharged water from the wastewater treatment of the Dalin Tzu Chi Medical Center before experiment, except the Total Nitrogen (TN) amount, the different kinds of water quality report from the rest have met the “agricultural irrigation water standard”. The results indicated that the Nitrogen nitrate had the highest density (28.65mg N/L) of the Total Nitrogen (TN), which might reduce to 15.99 mg N/L upon artificial wetland treatment that made a reduction rate of 44%. Due to the model field was at the activated “adaptation period” at the beginning that it did not achieve the expected reduction efficiency because the green plants has just started to grow so the density was low, while the carbon source for de-niter function was also insufficient. As to the Nitrogen nitrate ridden efficiency at the FWS wetland and SSF wetland, the former was 15% and the latter was 34%, which indicated SSF wetland has stronger ridden efficiency than FWS wetland.
When the experiment has moved to stable stage (six months), the daily water discharge rate was increased to 70m3/d, which equaled 0.11m/day of the hydraulic loading rate. The results indicated that the Nitrogen nitrate has reduced from the original 37.58 mg N/L to 11.98 mg N/L with 68% of ridden efficiency. It is the same as the other wetland Nitrogen nitrate ridden efficiency under the same conditions on the documentary records. Further, to compare the Nitrogen nitrate ridden efficiency of the FWS and SSF wetlands, the Nitrogen nitrate ridden efficiency of the FWS was 2.48 gN/m2/d, and SSF, 3.61 gN/m2/d, which indicated SSF wetland has better Nitrogen nitrate ridden efficiency than that of the FWS wetland. Such comparison proved that data of the model field at the activated “adaptation period” and the operational function after the stable stage, the performance of the FWS and SSF wetlands was the same. Due to after the wetland getting into the stable stage and flowed into the FWS and SSF wetlands, of the data obtained from different sample taking observation stations, the Nitrogen nitrate ridden speed was higher than any other station, on the contrary, the incoming flow of the wetlands at the adaptation stage had no such performance. While high N/P incoming flow density (incoming flow contained no positive phosphoric acid density), and amino nitrogen and nitrous acid showed no increasing value at the wetlands. Therefore, the nitrogen nitrate was ridden through de-niter function at the artificial wetland to leave the wetland system model field. |
