臺灣人工濕地可持續經營管理的思維與策略

Sustainable Management Strategy for Taiwan's Constructed Wetlands

賴榮一(Jung-Yi Lai)

指導教授 ： 堀込憲二 ； 郭城孟

中原大學/設計學院/設計學博士學位學程/博士(2017年)

https://doi.org/10.6840/cycu201700070

摘要

行政院環保署於我國各河川灘地補助建置的水質淨化人工濕地中，有九處受列於內政部營建署之「國家重要濕地」系統。環保署自2002年河川污染整治年起，有鑑於公共污水下水道系統的緩慢進度，開始輔助地方政府在各污染水源附近、受污染的河川支流匯流處，建置水質淨化人工濕地，人工濕地的建置目的，是為「減緩」鄰近地區在污水下水道接管率提升前的一種控制污染惡化程度的臨時性淨水設施，因該設施技術是由歐美等先進國家引入臺灣，建置初期具有臨時性、實驗性及示範性的意涵。研究者自2003年起參與隸屬九處人工濕地之一的新竹縣頭前溪竹東人工濕地總體規劃，其後為了解濕地完工運作後的淨水效益，於2009年執行「新竹頭前溪竹東高灘地第一、二期人工濕地植物變遷與水質淨化調查研究」案，並得初步水質淨化成效結論。延續前期調查基礎，本研究持續於新竹頭前溪第一、二期人工濕地的自設監測樣區進行維護管理、植群紀錄以及水質採樣，藉以瞭解人工濕地維護管理前後差異與水質淨化成效。
本研究參考環保署於人工濕地推廣初期編撰的水質自然淨化濕地操作建議，與九處人工濕地之主管機關與維護管理單位進行營運後之深度訪談，因九處人工濕地分處於臺灣之北、中、南、東不同的河川灘地，本研究再以各人工濕地之歷年成效評估文獻，交叉討論分處於臺灣不同區位環境的人工濕地所產生的各別與共同問題。調查發現，頭前溪第一二期人工濕地因長年的淤積使河道變形、變窄，可容受水體以及水力停留時間已與完工階段具極大差異、各池區單元的淨化型水生植物經自然演替與維護管理已消失3-7種；另各處人工濕地水質淨化與維護管理具有水中懸浮物（SS）去除率偏低、生化需氧量（BOD5）去除率偏低、氨氮（NH3-N）去除率不穩定、水生植物過剩與不足、清淤間隔期程過長、撈除植物就地覆蓋、棄置，以及臺灣河川特性影響淨化去除率等共通性問題；在規劃營運的問題上則具有濕地場址遭極端強降雨破壞、極端降雨頻度趨高、人工濕地闢建的先天弱勢以及河川區域植物栽植限制等共通性問題，本研究各別討論提出建議。經過污水處理場或礫間淨化設備後的水體再進入人工濕地二次淨化，會因人工濕地位處於完全開放環境，產生RPI值檢項升高的現象，判讀現階段我國營運之獨立型礫間淨化設備RPI值數據，淨化成果較串聯式佳。
因應未來污水下水道接管率提升以及極端降雨現象趨頻，本研究建議將臺灣的人工濕地導入綠色基礎設施概念，將其定位保存並推廣再建造。

關鍵字

重要濕地；新竹頭前溪；人工濕地；極端降雨；可持續經營管理；綠色基礎設施

並列摘要

Among the water-purification constructed wetlands along various local river basins subsidized by Environmental Protection Administration, Executive Yuan, R.O.C., nine of them are listed on "Important Wetland System" as determined by Construction and Planning Agency, Ministry of the Interior. The Environmental Protection Administration initiated the river clean-up remedies starting in 2002. Because of the slow development of public sewer systems, it decided to assist the local governments in building water purification systems on constructed wetlands along various polluted water sources and river tributaries. Constructed wetlands are a temporary water purification facility to slow down and to control the deterioration of pollution before the sewage treatment rate increases in neighboring areas. As this technology was introduced from developed countries in Europe and the United States to Taiwan, the early constructions were temporary, experimental and exemplary. Since 2003, the author has participated in the general planning of the "Zhudong Highland along the Hsinchu Touchien Riverside" project, which was one of the nine important national wetlands. In order to learn the effects on water purification after the construction of the wetlands, the author conducted the "Investigation and Research of Plant Transitions and Water Purification of Zhudong Highland along Hsinchu Touchien Riverside in the First and Second Stages of the Constructed Wetland Projects" and found positive results on water purification in 2009. In order to investigate the difference before and after starting maintenance management and the performance of water purification of the constructed wetland, the study has been continuously doing maintenance management, vegetation recording and water sampling in the monitoring area of the First and the Second Stages of Hsinchu Touchien Riverside Constructed Wetlands on the base of previous investigation.
According to the natural water purification wetland operation guideline written by Environmental Protection Administration during the initial development stage of constructed wetlands, his study has thoroughly interviewed the competent authorities and the maintenance management units of the nine constructed wetlands for their performance since the operation started. Because the nine constructed wetlands locate in different river basins in the north, middle, south and east of Taiwan, the study will also refer to historical evaluation reports and studies of these constructed wetlands. Cross discussions will be conducted regarding common issues faced by constructed wetlands in different areas of Taiwan. Because years of deposit has made the river channel deformed and narrow, the study shows that the water capacities and hydraulic retention times of the First and the Second Stages of Hsinchu Touchien Riverside Constructed Wetlands are significantly different from the conditions when the construction was just completed. Three to seven purifying aquatic plant species have been extinct due to natural evolution and maintenance management. Among all of the water purification process and maintenance management of constructed wetlands, several common problems occur: low suspended solid (SS) removal rate, low biochemical oxygen demand (BOD5) removal rate, instable ammonia-nitrogen (NH3-N) removal rate, surplus or deficiency of aquatic plants, long dredging interval, disposal and coverage difficulties of removed plants at the scene and affected water purification rate by the river’s characteristics in Taiwan. For planning and operation issues, some common problems also occur: wetland site destructed by heavy rainfall, increasing extreme rainfall frequency, innate weakness of constructed wetland building and planting restriction along riverside. In this study, these problems would be individually discussed and recommendations would be given. When water stream which has been treated by a wastewater treatment plant or a gravel purification facility enters the constructed wetland for secondary purification, its RPI index would rise because the constructed wetland is a completely open environment. It is found that the RPI indices of independent gravel purification facilities presently operating in Taiwan are showing better purification results than the ones connected in series.
Because the prevalence rate of sewage and the frequency of extreme rainfall are both expected to rise in the future, this study recommends that constructed wetlands shall be introduced into the green infrastructure concept, in order to identify, to reserve and to promote re-building them.

並列關鍵字

Important wetlands；Hsinchu Touchien River；Constructed Wetlands；Extreme Rainfall；Sustainable Management；Green Infrastructure

參考文獻

2002，《台灣環境復育之新方向》，國家政策研究基金會。

2005，《河川水質淨化工法設計研究計畫》，p.1-1～p.1-2、p.22，行政院環境保護署。

2006，《河川水質淨化工法設計研究計畫》，行政院環境保護署。

2007，《建立河川水質淨化工法指導原則暨評鑑計畫》，行政院環境保護署。

2005，《河川水質改善現地處理工法-礫間接觸氧化法》，行政院環境保護署水質保護處。