dc.description.abstract | 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. | en_US |