薄膜蒸餾處理都市污水廠RO濃排液及染整廠廢水之實驗探討

An experimental study on membrane distillation for treating reverse osmosis concentrate from municipal wastewater treatment plant and for wastewater from dyeing and finishing plant

李易鴻(Yi-Hong Lee)

指導教授 ： 莊清榮

中原大學/工學院/化學工程研究所/碩士(2020年)

https://doi.org/10.6840/cycu202000468

摘要

工業用水的需求增加和人口成長快速，使得水資源匱乏成為各國重視的問題，而以薄膜技術從工業廢水及生活污水中回收再生水或海淡等為重點發展對象。薄膜蒸餾為近年漸被重視之技術，該程序可利用低階熱源或產業廢餘熱來產製高純度再生水，同時兼具水與能源的回收。
本研究利用直接接觸式薄膜蒸餾(DCMD)進行桃園北區水資源回收中心RO模廠之濃排液和染整廠廢水產製再生水之探討，實驗分為以管式模組產製再生水之試驗及以平板式模組分析長時間批次濃縮操作後的膜面積垢；另一方面也初步進行薄膜蒸餾之產水成本估算。
以桃北水資中心之RO濃排液產製再生水的試驗結果顯示，同一模組經多次試驗，整體通量逐次遞減，氯離子阻擋率從初始的99%下降並維持在約95%，經更換模組後，水質分析的各項數據如COD及氯離子等皆有下降之趨勢，並達到工業用途ClassA之標準。在長時間批次濃縮後的SEM分析結果顯示，60℃的MBR放流水之膜面有著片狀及粒狀結晶和大腸桿菌附著，50℃的RO濃排液之膜面積垢僅發現與MBR放流水相似的片狀及粒狀結晶，而70℃的RO濃排液則有著花瓣狀積垢物，從元素分析及FTIR結果發現，3者主要沉積物皆為碳酸鈣。在有充足廢餘熱作為MD之進料熱源時，MBR放流水+MD與UF+RO+MD的單位產水成本分別為29.8及32.2 NT$/m3。
以染整廠廢水為進料產製再生水的試驗結果顯示，從實驗後的滲透槽液水質分析判斷，未處理與MF前處理之水樣均會使薄膜出現潤濕的現象。經UF前處理之染整廠原始廢水及經浮除和沉降後的廢水皆可穩定產製再生水，然而不同取樣點會影響到UF模組進行前處理時的結垢程度。

關鍵字

薄膜蒸餾 ； 生活污水 ； 逆滲透濃縮液 ； 染整廠廢水 ； 再生水

並列摘要

The demand for water resources has increased dramatically with the concentration of urban population and rapid industrial development. Water scarcity has become an important issue for all countries of the world. The use of membrane technology to produce reclaimed water from industrial wastewater and urban sewage, or to desalinate seawater, is recognized as key target for water resources development. Membrane distillation is a technology that has received much attention in recent years for water and wastewater treatment. It can use low-grade heat sources or industrial waste heat to produce high-quality reclaimed water. It is a technology that can simultaneously achieves the dual effects of water and energy recovery.
In this study, experiments of direct contact membrane distillation (DCMD) was carried out to investigate the performance in producing reclaimed water from the concentrated effluent of RO pilot plant located at the Taoyuan North District Water Resources Recycling Center and from the wastewater of a dyeing and finishing plant. In this study, MD experiments with tubular modules was conducted first on the production of reclaimed water, and then used flat-sheet modules to analyze membrane fouling/scaling after long-term batchwise operation. In addition, this study also preliminarily estimates the cost of producing reclaimed water by membrane distillation.
Experimental results from the RO concentrated effluent showed that the MD flux of the same module is gradually reduced after repeated operations, and the chloride ion rejection is higher than 99% for the virgin membrane module and then gradually decrease to about 95% after repeated operation of the module. SEM analyses showed that the membrane surface has flaky and granular crystals and E.coli attached after a long time batchwise operation with MBR effluent at 60°C. When the feed was RO concentrated effluent at 50℃， only flake and granular crystals deposit were observed on the membrane surface. However, when the RO concentrate effluent was heated to 70℃ for feed of MD experiment , petal-like crystals was formed on the membrane surface after a long run. According to EDS and FTIR analysis, it is found that the above-mentioned inorganic salt deposits are mainly calcium carbonate.. Based on the sufficient waste heat provided as the heat source for MD, the water production cost is evaluated to be 29.8 and 32.2 NT$ / m3 for MD with MBR effluent and RO concentrate effluent , respectively, from Taoyuan North District Water Resources Recycling Center.
The results of MD experiments with dyeing and finishing plant wastewater as feed showed that, whether the wastewater is pre-treated with MF, membrane wetting occurs. However, if this wastewater is pre-filtered with 0.05 μm UF, the subsequent MD operation can stably produce high-quality pure water.

並列關鍵字

Membrane distillation ； urban sewage ； RO concentrate ； dyeing and finishing plant wastewater ； reclaimed water

參考文獻

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