薄膜蒸餾處理都市污水廠放流水之探討

因氣候變遷及工業用水需求增加等導致台灣近年來常發生缺水危機，因此以再生水解決缺水問題甚被重視。基於生活污水及事業廢水等之放流水是一穩定水源，以其產製再生水甚有發展之潛力。本研究利用薄膜蒸餾進行迪化污水廠之放流水產製再生水之探討，實驗分為直接接觸式薄膜蒸餾(DCMD)模場試驗及氣隔式薄膜蒸餾(AGMD)實驗室模組試驗，皆採用平板式模組，前者目的在於長效數據的取得，而後者則在於膜面結垢清洗試驗，另一方面也進行AGMD之產水能耗的模擬分析。模場DCMD試驗結果顯示，操作條件為進料溫度60℃，Re= 9500，滲透液端35℃及Re= 3200，每日操作4小時，經2個月操作其通量衰減甚微，約為15 kg/m2hr。SEM-EDS分析結果顯示，膜面有些許有機結垢物。藉由量測進料端及滲透端電導度所推算之離子阻擋率大於99%，若針對單一離子(Cl-)之濃度量測，其阻擋率達99.9%。實驗室AGMD試驗結果顯示，產水水質COD為10.32 ppm、Cl-濃度為1.55 ppm及NH4+為2.89 ppm，整體而言優於RO產水水質。膜面結垢清洗試驗結果顯示，利用0.1% NaOH及0.8% EDTA四鈉(40℃)當作清洗液，可有效將膜面上結垢物洗除並使通量回復至初始通量。本研究最後則藉由Memstill®概念，加入回流，進行平板式AGMD產水耗能模擬，薄膜有效面積為1×1 m2，進料及冷水入口溫度分別為80及30℃、流速0.01 m/s且回流比0下，有最低產水耗能為106.8 kWh/m3且通量為5.5 kg/m2hr。

關鍵字

薄膜蒸餾；都市污水；再生水

並列摘要

Due to climate change and the increasing demand of water for industry, Taiwan frequently faces an acute problem of water scarcity in recent years. Therefore, much attention has been paid for using reclaimed water to solve the problem of water shortage. Based on the effluents of domestic sewage and industrial waste water are large and stable water resources, the production of reclaimed water from these effluents will have great potential. In this study, membrane distillation was used for effluent treatment from Dihua sewage treatment plant (STP) to produce the reclaimed water. Experiments were divided into direct contact membrane distillation (DCMD) pilot test and air gap membrane distillation (AGMD) laboratory module test, the former was used for long-term data obtained while the latter was designed to implement the cleaning test for fouled membrane. In addition, simulation analysis for energy consumption of AGMD to produce reclaimed water from STP was also carried out in this study. Pilot DCMD test using flat sheet module with ePTFE membrane was conducted under feed temperature at 60℃and Re= 9500 while the permeate side at 35℃and Re=3200.The flux decline obtained by 4 hours operation per day and 2 month continuous operation is not significant, its value being about 15 kg/m²hr. Based on the measurement of conductivity in feed and permeate, respectively, to determine the ion rejection, results showed that the ion rejection reaches 99%. By measuring the Cl- ion concentration, it appeared that the rejection was 99.9%. SEM-EDS analysis for fouled membranes showed that the fouling components are mainly from organic matters. Based on the COD, Cl- and NH4+ measured from the produced water, it clearly indicated that the water quality from MD is better than that by RO. Experimental results of AGMD showed that 0.1 wt% NaOH or 0.8 wt% EDTA-4Na solution can wash away the fouling on the membrane surface and the cleaned membrane has flux nearly same as that from virgin membrane. Based on Memstill® concept for heat recovery, the thermal energy consumption of AGMD was also estimated. Under the given conditions of flat plate module 1x1 m2 , temperatures of feed inlet and after heater were at 80 and 30℃, respectively, and the superficial flow velocity in the module channel was 0.01 m/s, the thermal energy consumption estimated was 106.8 kWh/m3 and the flux was 5.5 kg/m2hr.

並列關鍵字

Membrane distillation ； domestic sewage ； reclaimed water

參考文獻

莊順興(2011) “廢污水回收再利用技術評估”，財團法人中技社。

鄭于廷(2016) “薄膜蒸餾產製再生水之實驗探討”，碩士學位論文，中原大學化學工程學系，桃園市

蔡宗佑(2013) “薄膜液體貫穿壓力(LEP)之研究”，專題研究論文，中原大學化學工程學系，桃園市

Alkhudhiri, A., et al. “Treatment of high salinity solutions:Application of air gap membrane distillation. ” Desalination,287 (2012) 55-60.

Alkhudhiri, A., Darwish, N. and Hilal, N., “Membrane distillation: A comprehensive review,” Desalination,287 (2012) 2-18.

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薄膜蒸餾處理都市污水廠放流水之探討

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