The overall efficiency evaluation of the wastewater treatment plant and grey water reclamation system

[[abstract]]國立暨南國際大學校區污水處理廠扮演著區域性水污染防治之重要角色，但隨著環保法規趨於嚴格及設備老舊問題，過去所設計之處理設備，已不符合現今所需求。因地理位置因素，水源取得受到限制，為了增加可用之水源，推動中水回收再利用計畫。在中水系統設計之初，未因地制宜，造成日後維護操作之困難。因此本研究針對污水處理廠及中水回收系統進行評估，以改善舊有設備及操作缺失，並以中水水質標準，評估提升污水廠處理效能之可行性。 評估結果顯示，污水處理廠及中水回收系統總計有九大項缺失，其中，溶氧控制、SBR反應槽之攪拌機、污泥濃縮槽、消毒單元之加藥系統及景觀池等已完成相關改善計畫，另外SBR反應槽之散氣管、雨水收集系統之機械式攔污柵、中水回收系統之輸水管線及宿舍沖廁系統則已完成相關評估但尚未落實改善。 在消毒單元以餘氯控制加藥取代現有定量加藥方式，餘氯濃度控制在2～2.5 mgl-1之間，能使放流水中大腸桿菌群符合中水標準。景觀池因優養化問題，需加強污水處理廠脫氮除磷效能，在氮系方面，控制SBR處理程序時間方法約可達到25 ％硝酸鹽氮去除率；外加醋酸鈉為缺氧相碳源方法約可達到30 ％硝酸鹽氮去除率；在磷系部分，則評估以多元氯化鋁(PAC)除磷，當加藥濃度為40 mgl-1，磷酸鹽去除率可達100 ％，其加藥量為6(噸/year)，加藥費成本為228,000(元/year)；產生化學污泥24(噸/year)，其清運成本為96,000(元/year)。[[abstract]]The wastewater treatment plant in National Chi Nan University played an important role of prevention and control of regional water pollution. As the more strict regulation of environmental protection and the outdated apparatus of treatment plant, the treatment apparatus designed in the past have already not accorded with the new demand nowadays. The source of water is limited due to the geographical factor. In order to increase the available source of water, promotion of the grey water to retrieve and reuse is necessary. The grey water reclamation system constructed in National Chi Nan University had not suited measures to local conditions, and it resulted in the difficulty of operation. Thus, this study assessed systematically the functionalities of the wastewater treatment plant and the grey water reclamation system to improve the problems of old apparatus and operational deficiency. These two systems were assessed according to the water standard of grey water and further suggested the strategies to improve their efficiencies. There were nine deficiencies in both of the wastewater treatment plant and grey water reclamation systems. The improvement of five problems, including dissolve oxygen control, mechanical agitator of Sequencing Batch Reactor (SBR), sludge thickener, injector system of disinfection unit and reservoir, had already been finished. In addition, the assessment of other problems, including coarse bubble diffuser of SBR, mechanical screener of rainwater collection system, water pipeline of grey water reclamation system and lavatory system in dormitories, had also been finished, but not been improved yet. In the study, residual chlorine concentration was controlled by chlorine measurement instrument instead of conventional fix dose control in disinfection unit. The experimental result showed that Escherichia coli in grey water can be reduced to accord with grey water quality standard while the chlorine residual concentration is maintained at the level of 2-2.5 mgl-1. Because of the reservoir has already faced to eutrophication problem. It is needed to enhance the nitrogen and phosphorus removal of the wastewater treatment plant. In the nitrogen part, 25％ removal efficiencies of nitrate can be improved by controlling the stage time of the SBR process. By using sodium acetic acid as carbon source in anoxic phase can further achieve 30％ removal efficiencies of nitrate. In phosphate part, phosphate can be removed by poly aluminum chloride (PAC). About 100％ removal efficiencies of phosphorus could be achieved when PAC demand was 40 mgl-1,. The total PAC demand is 6 ton/year, and the cost of expenses for PAC is 228,000 NT$/year. The amount of produced chemical sludge is 24 ton/year, and the cost of expenses for treatment and disposal is 96,000 NT$/year.[[note]]碩