Real-Time Transfer Efficiency Monitoring for Wastewater Aeration Systems

論文發表人: 呂紹元(加州大學洛杉磯分校土木與環工系博士班)

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本研究針對一般民生污水的處理發展了一套即時監測系統，並用以進行曝氣時能量使用與操作成本的分析：曝氣是民生廢水處理系統中最為耗能的一個單元操作流程。為了增進氧氣傳送速率，細氣泡型曝氣盤(fine-bubble diffusers)受到廣泛的採用。然而由於處理污水中充滿著各種污染物及微生物構成的活性污泥，這類的曝氣盤的氣孔在長時間的使用中很容易被堵塞；此一現象將大大減低曝氣盤的效果與使用壽命。堵塞的情形隨著污水處理廠的操作而有不同，且一般皆由人工清洗的方式來恢復處理效果；而清洗會造成操作成本的提高。本研究提供一種即時監測的方法來量化曝氣盤受到污泥所堵塞的情形，並藉以判斷何時清洗曝氣盤最符合經濟效益。逸氣測試方法(off-gas test)是現今測試氧氣傳輸效率最快且正確的方法之一，而本研究針對此測試法進行改良並使之成為一即時監測/紀錄的系統。實地測試的結果發現：1.清理前後氧氣傳輸效率確有提升 (15%→18%)；2.即時監測結果與長期觀測結果相符；3.此監測法可提供正確並即時的氧氣傳遞資訊，未來當可用於曝氣馬達的回饋控制系統中以提高能源使用的效率。

 

Aeration is the most energy intensive unit operation in municipal wastewater treatment. To improve oxygen transfer rate, fine-pore diffusers have been wildly applied in aeration practice. However, during operation, this type of diffusers suffers from fouling and scaling problems, which rapid decline in performance and significant increase in energy costs. Diffusers must be cleaned periodically to reduce energy costs. The cleaning frequency of diffusers is site-specific, and is shown by the reduction of oxygen transfer efficiency (OTE) with time in operation. Off-gas testing is the only technique that can measure real-time oxygen transfer efficiency. This paper presents time-series of off-gas testing measurements and their applications, which show the potential for full-scale implementation of energy-conservation practices. Our results include the real-time prediction of plant load and alpha factors from off-gas testing, as well as the quantification of the increased energy costs for aeration. Our off-gas analyzer is being used to develop an aeration efficiency monitoring protocol, and an aeration feedback control system for air blowing units.