地下流式人工溼地對都市污水淨化之成效

Abstract

鑒於台灣本土現地參數不足，本研究於自然環境中施作一人造濕地以處理都市污水，變換不同之操作方式求取最佳處理效果。於關渡取用舊貴子坑溪溪水，為接觸曝氣及地下礫間處理複合式人工濕地，主要之污染去除機制為生物膜對污染質之分解。 研究結果顯示，移除效果最為顯著之水力停留時間為1天，平均移除率為，懸浮性固體57.4%，氨態氮13.7%，生化需氧量29.8%，磷酸鹽1.6%。而懸浮性固體的入流濃度維持在20mg/L以下，氨態氮入流濃度5.5mg/L以上則會有明顯之去除效果。本研究結果對於磷酸鹽之去除沒有顯著之效果。地下流式人工濕地持續使用約120天之後，需將槽內水放空以清洗孔隙，乾濕交替的操作維護方式可維持較佳之污染去除效率。

The purpose of this study is the use of subsurface flow constructed wetlands to treat domestic wastewater near Kuei-tzu-keng stream. Biofilm decompose on the surface is the primary removal mechanism. The gravel bed subsurface constructed wetland was used to investigate the removal efficiencies of SS, NH4+-N, BOD5, and PO43-. Results showed the removal efficiency is optimum when HRT were 1day. The averages of removal rate of SS, NH4+-N, BOD5, and PO43- were 57.4﹪, 13.7﹪,29.8%, and 1.6﹪respectively. There was a significant correlation between removal efficiency and inflow concentration of SS, NH4+-N, and BOD5. However removal efficiency significant increase as the concentration was below 20mg/L in SS and 5.5mg/L in BOD5. Removal efficiency of phosphorus in this experiment is insignificant. To avoid clogging and anaerobic, the wetlands should dry after 120days treatment and lead to aeration for treatment.