逆滲透薄膜處理二級放流水再利用實廠操作–以內湖污水處理廠為例

Municipal Reclaimed Water in NeiHu Wastewater Treatment Plant Using Reverse Osmosis Membrane in secondary Effluent.

洪榮昌(Jung-Chang Hung)

指導教授 ： 陳孝行

國立臺北科技大學/工程學院/環境規劃與管理研究所/碩士(2005年)

https://doi.org/10.6841/NTUT.2005.00334

摘要

本研究選擇以內湖廠經二級生物處理之放流水，進行逆滲透系統長時間連續運轉，藉以觀察探討逆滲透系統運轉特性、處理水量及水質，並分別在不同操作條件下，觀察比較處理水量、水質、效率、分別適用之用途及操作成本等。
運轉期間，提高逆滲透薄膜入口壓力時，流通量、回收率及去除率均會提升，滲透液水質變佳。此外，處理都市污水若未使用消毒滅菌設施，將造成快速的生物性污堵，導致薄膜入口壓力隨運轉時間而明顯降低，薄膜入口端與濃縮液端之壓差亦隨時間而明顯增加，連帶影響滲透液水質及產量，在未使用UV消毒裝置期間，流通量較原通量降低了17.5%。
砂濾槽對懸浮固體物、濁度、COD、BOD、氨氮之去除率依序分別為85.6%、74.1%、35.9%、27.1%、22.1%，TDS之去除率僅3.3%。活性碳吸附槽對懸浮固體物、濁度、COD、BOD、氨氮之去除率依序分別為31.8%、47.8%、12.0%、11.7%、11.9%， TDS去除率僅4.6%。在本逆滲透系統，活性碳吸附槽處理水質與砂濾槽處理水質差距不大，其設置目地值得再行探討。筒式過濾器對懸浮固體物及濁度之去除率分別僅為25%及6.7%，其他TDS、氮、磷等則有增加之情形，且在筒壁發現黏狀物，推測為上游活性碳吸附單元溢流高微生物處理水之故。
近十個月連續運轉，逆滲透系統產生之污堵主要為有機性及生物性之污堵，以0.5%氫氧化鈉溶液進行清洗可達到到清洗效果恢復質量傳送係數MTCW (Mass Transfer Coefficient, MTC)值，清洗過程發現，有效薄膜化學清洗必定具有色、味、泡沫之特徵，可作為操作者重要參考。依本研究檢驗項目，RO滲透液再經過氣提及消毒之後，可達飲用水標準，處理成本為41元/m3，推測應為未量化之故。砂濾槽、活性碳槽、筒式過濾器等單元處理水，亦符合短期灌溉用水標準及環境景觀用水低接觸性標準。

關鍵字

薄膜 ； 逆滲透 ； 預處理 ； 化學清洗 ； 水再利用

並列摘要

This research is based on the experiments conducted in secondary Effluent in NeiHu Wastewater Treatment Plant using Reverse Osmosis System (RO) under study for a period of 10 months in non stop operation. These experiments enabled the understanding of the operation of Reverse Osmosis System, qualitative and quantitative water treatment under different controlled environment using the system. They also afforded the analysis of water treatment volume and its quality, operation efficiency, uses of Reclaimed Water (RW) and costs of treatment.
During the experimental period, observations showed that when the pressure is increased at the input, the volume of flow, recovery rate, and rejection rate increase, the quality of the water that permeated through the membrane improves. However, urban wastewater treatment for Potable Water requires operation of the (RO) system with disinfecting chemicals, equipment, and media, without which, bio-fouling rapidly generates and spreads, resulting in reduced pressure at the input over a short period of time. The disparity in pressure between the input at the membrane and the concentrated fluid sharply increases and diminishes the quality and volume of the output of permeated water. Compared with the period prior to the installation of the auxiliary disinfecting equipment, after installation (of the auxiliary equipment) the overall volume of flow of the output decreased by 17.5%.
Utilizing Sand Filtration (SF), the rejection rates for Floating Solids, Turbidity, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and NH3 are 85.6%, 74.1%, 35.9%, 27.1%, and 22.1% respectively. There is a 3.3% Total Dissolved Solids (TDS) rejection.With Activated Carbon Filtration (ACF), the rejection rates for Floating Solids, Turbidity, (COD), (BOD), and NH3 are 31.8%, 47.8%, 12%, 11.7%, 11.9% respectively, including a 4.6% rejection of TDS.
However, when Reverse Osmosis is utilized, the water quality through (ACF) is similar to the result of (SF). Therefore the Activated Carbon Filtration does not present a significant advantage economically. Further, the Carbon Cartridge Filter rejects Floating Solids & Turbidity only at rates of 25% and 6.7%. TDS, Nitrogen and Phosphorous levels remaining in the water are much higher. And finally, there is the additional problem of algae forming on the wall of the cartridge as a result of the high volume of bacteria generated from the upstream carbon module.
In the 10 months continuous operational study of the (RO) System (including the auxiliary (SF) & (ACF), the fouling generated is primarily organic fouling and bio-fouling. This fouling could be reduced or eliminated by using 0.5% NaOH. Once the fouling is reduced or removed, the MTCw value will also be restored. (Note: In the cleaning process, it’s important for the plant operator to pay close attention to the color, smell & foaming action the chemical displays in the system.) Reverse Osmosis permeated water could meet the potable drinking water standards once processed through air stripping and disinfection. Although, the volume generated is sufficient for use in the plant, the cost of treatment is TW $41/m3 because limited volume is handling through an (RO) system.This study concludes my belief that the operational costs of (RO) treatment can be reduced if, and when, there are methods utilized to increase the volume rate. Until those methods are developed and implemented, the treated water resulting from the lower cost treatment of using only sand filtration (SF), and cartridge filtration (ACF), without (RO), are adequate to meets the significant demands for Reclaimed Water (RW) standards suitable for agricultural irrigation as well as landscape irrigation water requirements.

並列關鍵字

Reverse Osmosis ； chemical cleaning ； membrane ； Reclaimed Water

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