脫硝處理高濃度硝酸鹽廢水流體化床程序影響之研究

楊綠村

指導教授 ： 林勝雄

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

中文摘要
化學工業排放廢水量大，而許多化學工業廢水中所含氮系污染物之超量殘留於水體，極易造成環境生態保育不平衡。目前國內現有之廢水處理設施也以好氧生物處理為主，但其所需動力及土地面積龐大，且產生大量的生物污泥，徒增許多污泥處置所造成的操作維護費用。厭氧流體化床具有高污泥濃度及良好之質傳效率，使其程序負荷和反應槽高度提高，大幅減少反應槽體積，進而減少土地的需求；此外廢棄污泥量減少，亦大幅節省污泥處置的費用。
本研究所選擇的硝化纖維製程廢水，含有高濃度的無機氮化物，一般生物方法及物化方法不易徹底去除，因此以懸浮性生物脫硝程序進行研究。研究結果除以一般有機物去除效率作為指標外，亦增加無機氮化物的去除效率進行探討，以達污染物完全去除之目的。
由厭氧脫硝流體化床程序之研究成果顯示，於模型試驗中，經過長時間的連續操作，就反應槽的處理效率而言，廢水進流量為1.77 L/hr，反應槽體積11.45 L，HRT在6.47小時，COD及NO3ˉ-N體積負荷為6.31 kgCOD/m³.day、2.64 kgNO3ˉ-N/m³.day下，COD及NO3ˉ-N的去除率分別可達到94﹪及97﹪。
依據上述的操作結果運用在實廠操作中，廢水進流量在70 m3/hr，反應槽體積320 m3，HRT在4.57小時，COD及NO3ˉ-N體積負荷為7.59 kgCOD/m³.day、2.94 kgNO3ˉ-N/m³.day，COD和NO3ˉ-N的去除率分別為72~94﹪和61~98﹪的範圍。此為目前操作上的極限，亦可為後續工程設計參考之依據。

關鍵字

脫硝 ； 流體化床 ； 厭氧 ； 硝酸鹽

並列摘要

Abstract
Chemical industries usually discharges a large amount of wastewater into a receiving water body. Many chemical wastewaters contain excessive nitrogenous pollutants that if untreated can cause considerable disturbances to a water ecosystem. Currently, aerobic digestion is a treatment method for dealing these wastewaters. The aerobic digestion not only consumes a large amount of power and land space, it also generates a large quantity of sludge. To overcome these problems, anaerobic fluidized bed (AFB) system provides an excellent alternative. The latter treatment has the advantages of operating at a high mixed liquor suspended solids concentration as well as high mass transfer efficiency. Hence the process loading and reactor height can be significantly increased, leading to a reduction of reactor volume and land space requirement. In addition, the amount of sludge produced in the anaerobic system is considerably less than the aerobic counterpart. The nitrocellulose wastewater was selected for the present work. This wastewater contains quite high nitrogenous and organic concentrations and treatment of this wastewater by aerobic digestion is extremely difficult. Therefore, pilot-scale AFB experiments were undertaken in the present investigation to analyze the efficiencies of nitrogenous and organic removal.
The experimental tests were conducted in a continuous fashion with an aim of achieving optimum operations of the AFB process. Test results indicate that 94% COD removal and 97% NO3ˉ-N removal are realized under the operating conditions of 6.47 h HRT (hydraulic retention time), 6.31 kgCOD/m3-day and 2.64 kgNO3ˉ-N/m3-day loadings. As a comparison, the HRT for real plant operations was 2.67 h, and the COD and NO3ˉ-N volume loadings were 5.32 kgCOD/m3-day and 2.64kg NO3ˉ-N/m3-day, respectively. The corresponding COD removal fluctuated between 63 and 95% and the NO3ˉ-N removal ranged from 23 to 90% for plant operations.
The experiences of plant operations indicate that the COD and NO3ˉ-N removal is not good enough. Hence adjustments of the operating parameters are necessary. After the HRT was raised to 4.57h, and the COD and NO3ˉ-N volume loadings were modified to 7.59 kgCOD/m3-day and 2.94 kgNO3ˉ-N/m3-day, the COD and NO3ˉ-N removal was elevated to between 72 and 94% and between 61 and 98%, respectively. These COD and NO3ˉ-N removal figures provide good information for engineering design.

並列關鍵字

HASH(0xbf212d8)

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