水生植物在人工濕地淨化作用之探討

Abstract

以現地試驗方式，進行不同水生植物對水中生化需氧量移除之效果探討。以供人工濕地自然淨化作用，採用水生植物種類，及其管理建議。於台北縣新海橋下人工濕地，選定15種優勢物種，以一有植栽試驗桶搭配一無植栽試驗桶設置。每隔固定滯留時間進行採樣，對其株高、植物密度等指標作調查，並分析其桶內與入流之生化需氧量濃度。 不同植物之一階反應速率常數如下，水龍為0.215、覆瓦狀莎草為0.450、高野黍0.386、荸薺為0.311、大安水蓑衣為0.260、馬藻為0.221、斷節莎為0.316、過長沙為0.099、田字草為0.305、水毛花為0.068、開卡蘆為0.432、異花莎草為0.211、水丁香為0.207、青萍為0.093、香蒲為0.350。斷節莎、過長沙、開卡蘆、香蒲，隨生長天數增加而移除量增加；水龍、覆瓦狀莎草、高野黍、荸薺、大安水蓑衣、馬藻、田字草、水毛花、異花莎草、水丁香、青萍，則隨生長天數增加而下降。此外，對於不同植物有不同之入流濃度限制，如對於覆瓦狀莎草，入流濃度需達51.1 mg/l，水龍是7.4 mg/l、大安水蓑衣為7.9 mg/l、馬藻為8.2 mg/l、斷節莎為43.8 mg/l、過長沙為29.9 mg/l、田字草為12.2 mg/l、水毛花為14.5 mg/l、香蒲為10.1 mg/l，才有顯著移除量之產生。而高野黍、荸薺、開卡蘆、異花莎草、水丁香、青萍，則在極低之入流BOD濃度下，即有移除量。人工濕地中移除生化需氧量之最佳植物，依其k20值作為排序，依序為k20值0.432的開卡蘆，0.386的高野黍，0.211的異花莎草。

The purpose of this study is to investigate efficiency of natural purification of aquatic plants in constructed wetland, and to manage different kinds of macrophytes. Two pots were arranged for each species, one planted and the other unplanted. Aquatic planted pots were sampled to analyze their heights densities of plants and BOD. In this study, fifteen species of aquatic plants were chosen. And, Phragmites vallatoria (Pluk. Ex L.), Eriochloa prrocera Retz., Cyperus difformis Linn., were suggested to be more suitable for reducing the concentration of BOD than other plants. The reducing rate constants were caculated 0.432, 0.386, and 0.211, respectively. However removal efficiencies of macrophytes depend on influent hydraulic loading rates. There is limitation in influent hydraulic loading rates. Some aquatic plant removal BOD as influent rate must reach a critertia concentration. And, some macrophytes don’t perform efficifiency removal of BOD until the hydraulic loading rates reach particular concentration, such as Ludwigia adscendens, Hygrophila pogonocalyx Hayata, Potamogeton crispus, Torulinium odoratum, Bacopa monnieri, Marsilea minuta, Schoenoplectus mucronatus subsp. Robustus, Typha angustifolia L.. The minimun hydraulic loading rates of this eight species are 7.4 mg/l, 7.9 mg/l, 8.2 mg/l, 43.8 mg/l, 29.9 mg/l, 12.2 mg/l, 14.5 mg/l and, 10.1 mg/l.