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  • 學位論文

直接接觸式薄膜蒸餾處理工業區MBR放流水與成本評估

An experimental study and cost evaluation on membrane distillation for treating membrane bioreactor effluent from Industrial district

指導教授 : 莊清榮
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摘要


由於工業用水大增及氣候變遷等影響,導致臺灣時常面臨缺水的問題,基於生活污水及工業廢水量大,近年來產製再生水技術備受關注,且政府也積極推動此技術的發展,利用廢污水產製再生水具發展潛力。 本研究針對桃園觀音工業區污水處理廠的MBR放流水,利用PVDF管式模組進行直接接觸式薄膜蒸餾( DCMD )試驗,目標為探究該類放流水以薄膜蒸餾產水之可行性,最後嘗試估算DCMD產製再生水之成本。 首先探討進料溫度變化對通量之影響,以MBR放流水作為進料,以進料流量為5 L/min進行四小時實驗,當進料溫度從50°C提升至70°C,其平均通量從2.3 提升至8.4 kg/m^2‧hr,可發現提高進料溫度對通量有明顯增加。以MBR放流水為進料,進料及滲透端溫度分別為60及30°C,進行十二小時MD實驗,探討有無進行進料預處理對膜面結/積垢與產水水質之影響,在SEM圖中可觀察到經過預處理的進料,其膜面有較少的結垢,在EDS分析中可以推測兩者的膜面結垢主要為有機化合物及少量的無機鹽類。而滲透槽水質分析中,COD及BOD等皆有下降趨勢,這表示薄膜有效阻擋非揮發性有機化合物,且滲透槽液氯離子濃度下降,顯示薄膜對離子具有良好的阻擋效果,而放流水中游離氨揮發通過膜孔至滲透端,使滲透槽內的pH值、電導度及氨氮濃度皆有上升。經二十四小時MD操作後進料未經預處理者其後段的平均通量與前段相比約有12%的衰退,而經UF預處理者則有29%的衰退,用清水掃流膜面一小時並以相同條件操作2小時,進料未經預處理者具有97%的通量回復,而經預處理者則有94%的通量回復。最後本研究嘗試估算當有充足廢餘熱作為MD進料熱源的條件下,依據此MBR放流水為MD進料之實驗通量,進料溫度為60及70°C之產水成本分別是NT$ 29.0及22.1 /m^3。

並列摘要


Due to the climate change and increased demand in water for industry leads to the problem of water shortage recently in Taiwan. Considering the large amount of industrial wastewater and domestic sewage discharged relatively stable, using this wastewater to produce reclaimed water has a great potential in the future. In this study, direct contact membrane distillation (DCMD) with self-assembled capillary PVDF membrane module was used for conducting experiments with MBR effluent from Taoyuan Guanyin Industrial District Sewage Treatment Plant. The aim was to explore the feasibility of membrane distillation technology for treating this effluent. Finally, the cost of producing reclaimed water from the waste stream with DCMD was also evaluated. When the MBR effluent was used as the feed with a rate of 5 L/min(Re=6141 in the shell side of the module) , showed the average flux of four-hour operation increases from 2.3 to 8.4 kg/m^2‧hr by increasing the feed temperature from 50 to 70°C, where the permeate side was maintained at 30°C. The effect of MBR effluent with /without UF pretreatment for feed of 12 hrs DCMD run on the fouled/scaled of the membrane surface and the quality of the water produced was also investigated, where the feed and permeate temperature were 60 and 30°C, respectively. In the SEM images, it was observed that the feed with pretreatment can give less membrane fouling. The EDS analysis showed that the organic matter and a little amount of inorganic crystals are the main deposits on the membrane. The measurements of permeate COD and BOD indicated that the membrane completely reject non-volatile organic compounds and, the measurements of permeate chloride ion concentration showed that this ion was almost completely rejected. Based on the measurement of pH, conductivity and ammonia concentration in the permeate, it is indicated that part of the ammonia nitrogen in the MBR effluent is volatilized and transported through the membrane pores to the permeate side. Experiments results showed that the average flux of later period of the 24 hours DCMD operation has a decline of about 12% for the feed without UF pretreatment, while the feed with UF pretreatment has a higher decline to 29%. Using clean water by crossflow to flush the fouled membrane after 24 hrs MD operation, it was observed that the cleaned membrane can give a 97% recovery of flux for feed with MBR effluent, and 94 % recovery for MBR effluent with UF pretreatment. Finally, based on the additional premise of sufficient waste heat provided as the heat source for MD, the water production cost by applying MD with this MBR effluent was also evaluated to be 29 and 22.1 NT$/m3 for feed temperature at 60 and 70°C, respectively.

參考文獻


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