極微濾薄膜去除天然有機物操作效能之探討

Abstract

本研究之主要目的在探討極微濾薄膜去除天然有機物之操作效能。其中，探討各種操作變因如回收率、壓力、 濃度、離子強度及pH值等之影響，也選擇不同薄膜材質對親疏水性有機物進行定濃度過濾實驗，希望藉由操作因子與薄膜材質的探討瞭解極微濾薄膜的操作性能。另外，針對不同地區水廠水質特性選擇適當的薄膜材質與操作條件，並評估極微濾薄膜在實廠應用之整體效能。 研究結果顯示，在主要控制因子為回收率、壓力、濃度、離子強度及pH值中，當操作壓力從70psi提高到100psi時，對腐植酸去除率提高較為明顯，且隨操作壓力增加，滲流率衰減減少。對進流濃度而言去除率隨著濃度升高而升高，滲流率衰減增加。至於改變回收率、離子強度及pH值方面去除率則差異不大。 從親疏水性水樣之定濃度操作實驗顯示，聚丙烯（PP,DK1812）薄膜對疏水性有機物種之處理效果較好，而磺化聚風□(SPS,ASP50)、聚醯胺(PA,ATF 60)材質則對親水性有機物之處理較好。且一般滲流率的衰減隨著水樣之疏水性越強越嚴重。 在實際原水操作結果發現，明德及寶山淨水廠水體有機物以疏水性為主，以DK1812薄膜處理較佳。而澄清湖淨水廠水體有機物則以親水性為主，以ASP50及ATF60薄膜處理較佳。整體而言，以極微濾薄膜處理對天然有機物、濁度、色度有極佳之去除效果(約70%~93.3%)，而對TDS、NH3-N、導電度亦有去除效果(約30% ~ 60%)。

The objective of this study was to investigate the effect of operational parameters such as ,recovery, pressure, concentration ,ionic strength and pH value, on the rejection rate and permeability of nanofiltration membranes for removing natural organic matters. Also, three types of membranes were chosen in this study to evaluate the performance of membrane by investigating operational parameters and materials . Experimental results showed that the efficiency of humic acid reduction was mainly affected by operating pressure, when the pressure was increased from 70 psi to 100 psi, the reduced efficiency of humic acid and the decline of membrane permeability decreased. In addition, the removal efficiency of humic acids increased with an increasing of influent concentration. To study the effect of pH value and ionic strength on the removal of humic acid by membrane filtration, it was found that the difference between pH4 to pH9 and ionic strength of 0.005m to 0.0117m was insignificant. As for recovery, the removal was not affected. Nanofiltration experiments conducted with a constant influent concentration of NOM indicated that the DK 1812 membrane has better removal efficiency for removing hydrophobic NOM than hydrophilic NOM; the ASP 50 and ATF 60 membranes have better removal efficiency for hydrophilic NOM . The decline of flux rate increases with increasing hydrophobic characteristics. When the nanofiltration technique was applied in Ming-te and Pao-shan Water Treatment Plants, it was found that the major NOM is hydrophobic. Hence the DK1812 membrane gives a better performance in removing hydrophobic NOM for these two plants. The major composition of water sample collected from Chengching Lake Water Treatment Plants is hydrophilic. It understood that the ASP50 and ATF 60 membranes are suitable for this water sample. In conclusion, the effects of operating parameters on the removing efficiency of NOM has been studied in this research. The results reveal that the nanofiltration is a desirable method for NOM, turbidity, and color (among 73% and 93.3%)of water samples collected from Water treatment plants. In addition, it is profitable to remove TDS and NH3-N(among 30% and 60%).