台大校園雨水再利用課題初探

Abstract

台灣雨量充沛但卻時常有缺水問題發生，因此能有效利用水資源是相當重要的課題。國立台灣大學正推動許多環境工程，對於節約用水提出了「廢水及雨水再利用」這個子題計畫來推行永續校園方案。利用收集雨水經過簡易過濾處理成為不與身體接觸之用水，是目前替代建築物自來水用水最普遍之方式。 本研究以國立台灣大學為對象，探討校園內設置雨水儲集並利用之合理性與可行性並且對於醉月湖水質做基本調查。建議以雨水排水系統管路收集雨水後匯入醉月湖以人工濕地處理系統做為前處理，再設計慢濾池處理後送至儲水槽儲存，最後再分送至各館舍再生水儲存桶儲存利用。 2006年校總區總用水量為1,965,083噸，預計雨水利用設計量為124,373噸/年，故以雨水替代之再生水用途用水量占校總區總用水量之6.94%。供水區總用水量為359,717噸/年，則雨水替代之再生水用途用水量占供水區用水量之34.58%。集雨區逕流量可得總收集雨量為272,632 m3/年，與雨水利用設計量136,373噸/年相比可發現將近有50%之收集雨量並未能有效利用到，表示可以再增加供水區域使得收集之雨水能更充分的被利用。計劃區域內可以替代的水量約為124,373噸/年，一年可省下1,119,357元(水價為9元/度計算)。

How to use rainwater more efficiently is very important in Taiwan because the problem of water shortage was maintained for past few decades. National Taiwan University (NTU) impels many projects and proposes the sub-plan, which is called “the reused of waste water and rainwater”, to accomplish sustainable campus. Using collected rainwater treated by simple filtration process to be water without coming in contact with the human body is the most common way to save the water resource. The reused of rainwater in main campus of NTU is investigated in this research. The rain water will be collected by drainage system and then entered into Zui-Yue Lake. It is also pretreated using constructed wetland and slow filtration tank then the treated water will be stored up. The collected water can be used by every building in campus. The usage of water in campus is 1,965,083 tons in year 2006, the estimated volume of the tap water is 124,373 tons/year. The rain water can be instead of the total usage of tap water at the ratio of 6.94%. The total water usage in water supply region is 359,717 tons/year and that of the ratio is at 34.58%. The total collected rain water in the water supply region is 272,632 tons/year.Comparison with the usage of designed quantity of rain water, 50% of rain water is lost. It represents the water supply region can be expanded and the rain water can be used more efficiently. The substituted water is about 124,373 tons/year. The cost of tap water in 2006 is NT 9 per cubic meter in campus. Therefore the cost of water can be saved about 1,119,357 dollars.