| 摘要: | 本研究利用超濾（UF）與逆滲透（RO）薄膜程序處理人工染料廢水(SDW)、都市污水(DW)、食品廢水(FPW)及TFT-LCD製程廢水(TFT-LCD)經薄膜生物反應槽（Membrane Bioreactor, MBR）處理之出流水，評估UF、RO程序回收再利用MBR出流水之可行性，並探討SDW MBR出流水水質特性對RO薄膜過濾機制的影響。 研究結果顯示，四種原水的MBR出流水中，僅有微量的懸浮物質，濁度介於0.01~1.82 NTU，大多以溶解性有機物及無機鹽類存在，其中有機物主要為溶解性微生物產物(Soluble Microbial Product, SMP)，其分子量分佈受到原飼水及不同MBR程序所影響，與傳統生物程序產生的SMP分子量分佈有所差異。MBR出流水經薄膜程序處理後，可有效去除出流水中溶解性有機物及無機鹽類，SDW、DW、TFT-LCD經由RO處理之滲透液導電度、TOC及TS之去除率，分別為85~98%、85~94%及94~99%，而FPW經由UF/RO處理後，滲透液導電度、TOC及TS之去除率，分別為91.1%、93.8%、90.9%，此外，RO對SMP有很好的去除效果，尤其對分子量較大的含芳香族SMP，有較高的去除率。 在以RO處理SDW過濾機制之探討中，發現RO膜表面累積微量有機物，且溶液擴散模式可有效推測滲透液濃度，誤差範圍小於±30%以內，顯示RO膜過濾SDW仍以溶液擴散為主要去除機制。此外，利用模式推測滲透液的TOC濃度均比實際滲透液中的TOC濃度低，其原因可能是微量有機物於膜面發生濃度極化，使得模式有低估的現象。 本研究另以模場進行長效性操作評估，DW經RO程序處理之造水成本為28元/噸，各項水質指數皆可達80~90%之去除效率，且滲透液可用於半導體Ⅳ級純水，或可作為超純水進料水。但若以工業取水成本評估，其造水成本仍偏高，未來若能實施水污費徵收、調整水價及以法規規範各產業之水回收再利用率後，以 RO 程序回收MBR出流水，仍然具有優勢與可行性。 The purpose of this research is to evaluate the feasibility of water reuse treated by UF and RO membrane processes. The processes treat four types of membrane bioreactor (MBR) effluent, containing synthetic dye wastewater (SDW), domestic wastewater (DW), food processing wastewater (FPW) and organic wastewater form TFT-LCD industry (TFT-LCD). Simultanesously, the mechanism for RO process for the rejection of contaminants in SDW is also supposed. The result shows that there is slight suspend solid in the effluent of MBR, and the major contaminants are salt and solute organic substances which almost consist of Soluble Microbial Product (SMP) in the effluent of MBR. Because of complex feedwater chemistry and distinct MBR process, the molecular weight distribution of SMP in MBR effluent and in traditional biological process is different. However membrane process can remove the residual solute organic substances and salt efficiently. The conductivity, TOC and TS removal efficiencies of SDW, DW and TFT-LCD RO permeate are 85~98%, 85~94% and 94~99%. For FPW permeate, the rejections of UF/RO process in terms of conductivity, TOC and TS are 91.1%, 93.8% and 90.9%, respectively. In addition, the rejection of RO membrane for SMP which have large molecular weight is efficient. According to the experiment treating SDW by RO, we find out that slight organic substances are accumulated on RO membrane. Because of the slight blocking phenomenon of RO membrane, we simulate the permeate water quality and the permeate flux by solution diffusion model to prove that solution diffusion is the major mechanism for RO process for the rejection of contaminants in SDW. The result show that the calculated concentration values in permeate are within ±30% of the experimental, so that solution diffusion model can be considered the major mechanism. Due to the small extent polarization concentration phenomenon on membrane surface, the TOC model results are tiny lower than the TOC experimental results. In order to find the potential of application and feasibility of RO process, the long-term investigation try to analysis the pilot treatment cost of DW. The cost for DW is 28 NT/ton and the permeate can reuse to the semiconductor Ⅳ water and the feed of pure water machine. So RO process has competitive advantage to treat MBR effluent to reuse. |
