Water resources are increasingly precious, so wastewater reclaiming has become an important source of water nowadays. There are many types of industry including conventional and hi-tech ones in the selected industrial processing zone, where different process wastewaters are treated by a centralized wastewater treatment plant. The effluent is then discharged into the ocean (EDO). On the other hand, among several other industries backside grinding (BG) wastewater generated by the IC (integrated-circuit) packaging and testing industry is treated by their owned wastewater treatment plants and then discharged onto land (EDL). Normally, BG wastewater is huge in quantity and it contains microscale and nanoscale particles. The objectives of this research were two-fold: (1) to evaluate the feasibility of using two tubular ceramic membranes (microfiltration and ultrafiltration) coupled with the electrocoagulation/electrofiltration (EC/EF) process to effectively treat the effluent discharged into the ocean, effluent discharged onto land, and BG wastewater for the purpose of reclamation; and (2) to investigate the best time for backwashing of membranes through the analysis of components of membrane fouling using resistances in series model. The experimental results showed that the ultrafiltration (UF) membrane (i.e., tubular TiO2/Al2O3 composite membrane) outperformed the mictrofiltration (MF) membrane (i.e., tubular Al2O3 membrane) in terms of permeate quality. But, generally, the later yielded a greater membrane flux. In the case of BG wastewater by UF and EC/EF, the quality of permeate met the tap water standards in terms of water quality items analyzed. As for EDO and EDL further treated by UF and EC/EF, all the analyzed water quality items of permeate, except pH and total dissolved solids, met the tap water standards in Taiwan. Thus, more efforts have to be made to reclaim these two types of effluent. Finally, the components of membrane fouling were analyzed using resistances in series model for the tested water specimens. The results showed that generally the irreversible resistance component (Rirr) had a greater contribution to a better quality of permeate than that of the reversible resistance component (Rr). It was also found that the magnitude of Rirr of BG wastewater was greater than Rirr values of the other two effluents. This might explain why the quality of permeate of the former was better than the latter. The results further indicated that Rr increased more than Rirr as the operating time elapsed, resulting in a limited improvement of permeate quality even a longer treatment time was employed. To recover the membrane flux to its optimum, in this study the best time for backwashing of membrane was determined based on the time at which Rr was greater than Rirr. However, the flux recovery was found to be in the range of 60-77% as compared with the initial flux for a virgin membrane in treating new batch of water specimens. The fraction unable to recover by backwashing might be contributed by Rirr in the membrane pores. A further acid washing would resolve this problem.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0210110-171633 |
| Date | 10 February 2010 |
| Creators | Lai, Chih-min |
| Contributors | Hsuan-hsien Yeh, Kuo-Jen Hwang, Gordon C. C. Yang, Ching-jung Chuang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0210110-171633 |
| Rights | withheld, Copyright information available at source archive |
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