STRATEGY FOR OPTIMUM MANAGEMENT OF WATER PURIFICATION SYSTEM WITH CONSIDERATION OF TOTAL ENVIRONMENTAL LOAD AND COST-BENEFTT

为了最大限度地减少水库蓄水的有机化合物负荷，通过实地测量和数值模拟水质，研究了包括低通量曝气、选择性取水和沿岸植被在内的水净化系统的性能。重点研究了溶解氧、营养物和有机物的行为。建立了一个水质模型，考虑了影响水质平衡的各种生化过程，从而反映了水质的季节变化。仔细确定模型参数，以便准确地再现现场数据，其中溶解氧平衡与低氧通气相关联被考虑在内。曝气系统是一种能够产生高溶解度细气泡的微泡曝气装置。除曝气外，还考虑了选择性回收操作对溶解氧分布的调节。为了最大限度地提高水的净化性能，我们假设了各种类型的系统运行场景，包括曝气和选择性回收。优化系统运行的基本思想是使水系统和大气环境的总环境负荷最小，并使成本效益最大化。在成本效益分析中，考虑了系统建设所需的初始成本和运行成本。提出了水质净化性能、成本和总环境负荷等参数，最终提出了曝气系统和选择性回收装置的最佳运行策略。另一方面，考虑到氧的溶解度和损失依赖于热结构的季节变化，为了找到最佳的性价比操作，对曝气系统进行了间歇运行的现场实验。通过水质测量，找到间歇式曝气系统的最佳运行方式，使能耗和二氧化碳排放量降到最低。作为水体净化的另一种方式，通过对天然湖泊的野外调查，研究了海岸带植被的营养摄取性能。本文的研究成果将为今后的环境工程提供一个新的水坝水库管理方向。此外，应用本研究结果可以使流域的总环境负荷最小化。少

In order to minimize the organic compound loads on a reservoir impoundment, performance of water purification systems including hypolimnetic aeration, selective withdrawal and vegetation in littoral zones were investigated by making field measurement and a numerical simulation of water quality. Focus was placed on behaviors of dissolved oxygen, nutrients and organic matters.A water quality model was developed so that seasonal variation of water quality by considering various biochemical processes involved in the water quality balance. Model parameters were carefully determined so as to accurately reproduce the field data, where dissolved oxygen balance associated with hypolimnetic aeration was taken into consideration. The aeration system was a micro-bubble aerator unit that is able to generate fine bubbles with high solubility. In addition to the aeration, selective withdrawal operation was considered to regulate dissolved oxygen profile. Various types of system operation scenarios we … More re assumed with respect to aeration and selective withdrawal in order to maximize water purification performance. The basic idea for optimizing the system operation is to minimize total environmental loads not only on the water systems but also on the atmospheric environment as well as to maximize the cost-benefit. In the cost-benefit analysis, the initial cost necessary for the system construction and the running cost were taken into consideration. Parameters indicating the water purification performance, the cost and the total environmental loads were proposed so that an optimum strategy for the operation of the aeration system and the selective withdrawal devices was finally proposed.On the other hand, an in-situ experiment on intermittent operation of the aeration system was carried out in order to find the best cost-performance operation by considering solubility and loss of the oxygen that is dependent on the seasonalvariation of thermal structure. The best operation of the intermittent aeration system was found through water quality measurement, which is able to minimize the energy consumption and emission of carbon dioxide.As one of another ways of the water purification, nutrient intake performance of vegetation in littoral zone was investigated through a field survey in a natural lake.The results from the present research program are to provide a new direction of dam reservoir management that is useful for environmental engineering use in the next years. Additionally, the total environmental loads on a river catchment can be minimized by applying the present research results. Less