以物質流分析淡水河流域內之有機物質與懸浮固體

Abstract

近年工商業過度發展，河川自淨能力遠不及污染物排入速率，因此導致都會區河川水質日益惡化。在無法確實掌握污染物總量與分佈之條件下，想要做好河川總量管制與規劃管理，是非常困難的。緣此，本研究的主題在於將河川流域視為一個被分析的系統，透過物質流（Material Flow）的概念，計算淡水河流域某斷年(1994)由社會生活圈進入環境的有機污染物與懸浮固體物，並與2003年污水下水道系統已啟用之條件作比較。在此有機污染物的含量以五日生化需氧量(5-day Biochemical Oxygen Demand ，簡稱BOD5)代表，而懸浮固體(Suspended Solids, SS)可代表部分的地表沖刷物。 研究成果顯示選定參數值η = 0.7的條件下，可推估2003年淡水河流域在污水下水道系統未運作之條件下，BOD5實際總人為排放量約為363,460 kg/day，SS實際總人為排放量約為1,031,830 kg/day；2003年污水下水道系統BOD5去除率佔實際總人為排放量19.55 ％，SS去除率佔實際總人為排放量7.30 ％。待迪化污水處理廠二級處理工程完工、加入處理污水的行列後，在理想操作條件與實際總人為排放量不變的條件下，總計可將淡水河流域BOD5去除率提升至41.56 ％，SS去除率提升至15.06 ％。未來內湖廠若進行第二階段工程，總計可將BOD5去除率提升至51.70 ％，SS去除率提升至18.81 ％。依照淡水河流域目前所規劃的污水處理廠處理能力，最高只能去除約51.7 ％的BOD5，而剩下未處理的部分則流動至環境中，未來應考慮其他替代方案以涵蓋此部分之污染物。由本研究所引伸的規劃理念，建議在未建設下水道系統之流域，應考慮相關的物質流動問題。 本研究成果建立淡水河流域人為產生BOD5、SS的物質流系統圖，期待相關概念能應用於都市廢水的管理工作。

River pollution is one of the environmental issues concerned gravely by scientists and engineers. Due to the excessive wasteload received, the water quality of the Tamshui River deteriorated for many years. This study was made to establish a basin-wide MFA framework to calculate the manmade mass flow of BOD5 and SS in the watershed. Also evaluated in this study were the removal efficiencies of the sewage treatment plants under operation. With certain assumptions, this study showed that in the year of 2003, the basin-wide inflows of SS and BOD5 were 1,031,830 kg/day and 363,460 kg/day, respectively. The existing sewage treatment plants could only remove 51.7 % of the BOD5 and 18.8 % of the SS. Therefore the remaining proportion of the polluted flows to the basin should be carefully examined for their sources. Because the majority of BOD5 and SS was known to come from the domestic source, a follow-up management program should be planned to reduce the pollutional loads contributed by the watersheds with no sewer systems provided.