This study addresses three major parts: (1) to establish the technology for the preparation of tubular ceramic membrane substrates; (2) to establish the technology for the preparation of tubular carbon/ceramic membranes; and (3) to reclaim water from chemical mechanical polishing (CMP) wastewaters by a combined treatment system of a novel simultaneous electrocoagulation/electrofiltration (EC/EF) process coupled with laboratory-prepared tubular composite membranes (TCMs) and evaluate its feasibility of water recycling and operating cost.
First, in this work the green substrates of tubular porous ceramic membranes consisting of corn starch were prepared using the extrusion method, followed by curing, drying, and sintering processes. Experimental results have demonstrated that an addition of starch granules to the raw materials would increase the porosity, pore size, and permeability of the sintered matrices but accompanied by a decrease of the compressive strength. It revealed that the membrane substrates with desired pore sizes and permeability could be obtained by adding a proper amount of corn starch. The nominal pore sizes of the prepared membrane substrates were ranging from 1 to 2 £gm. The membrane substrates thus obtained are suitable for crossflow microfiltration applications.
Second, the carbon/alumina TCMs and carbon fibers/carbon/alumina TCMs were obtained by the chemical vapor deposition (CVD) method resulting in a pore size distribution of 2 to 20 nm and a nominal pore size ranging from 3 to 4 nm. Besides, during the CVD process the reaction temperature was found to be the main factor for influencing the pore size of carbon fibers/carbon/alumina TCMs and the type of carbon fibers. When the reaction temperature was above or equal to 1000 ¢J, the pore size of TCMs increased due to the pyrolysis of thin carbon layers. The ¡§Tip-Growth¡¨ mechanism was found for tubular carbon fibers formation under such conditions. On the other hand, ¡§Base-Growth¡¨ (also known as ¡§Root-Growth¡¨) mechanism was found for curved and irregular carbon fibers formation when reaction temperature was under or equal to 950 ¢J.
Third, for reclaiming water from CMP wastewaters, experimental results of laboratory-prepared carbon/alumina TCMs incorporated into the custom-made EC/EF treatment module used was found to be capable of treating oxide-CMP wastewater in a proper manner. Permeate thus obtained had a turbidity of below 0.5 NTU and the removal efficiencies of TS (total solids content) and Si were 80% and 93 %, respectively. Further, for understanding the applicability of fractional factorial design and Taguchi experimental design, two laboratory-prepared carbon fibers/carbon/alumina TCMs (i.e., Tube B and Tube E obtained from two different preparation conditions) incorporated into the EC/EF treatment module were chosen for evaluating the performance of CMP wastewaters treatment. Permeate obtained based on the fractional factorial design of experiments had a turbidity of below 1.0 NTU and the removal efficiencies of TOC (total organic carbon), Cu and Si were all above 80 % except for the TS (i.e., ranging from 72 to 74%). Permeate obtained based on the Taguchi experimental design had a turbidity of below 0.3 NTU and the removal efficiencies of TS, TOC, Cu and Si were ranging from 82 to 91%. Apparently, similar optimum operating conditions were obtained from the fractional factorial design and Taguchi experimental design. Permeate thus obtained could be reused as the make-up water of cooling towers. The operating cost of Cu-CMP wastewater treatment based on a total water reclaim of 600 m3 per day was determined to be NT$ 98 (i.e., US$ 3.22) and NT$ 35 (i.e., US$ 1.05) per m3 of permeate for Case 1 (i.e., the filtration area of 0.0189 m2 in one EC/EF module) and Case 2 (i.e., the filtration area of 0.0801 m2 in one EC/EF module), respectively.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0827108-150304 |
| Date | 27 August 2008 |
| Creators | Tsai, Chi-Ming |
| Contributors | Chihpin Huang, Da-Ming Wang, Kan-Sen Chou, Yuan-Yao Li, Hong-Ming Lin, Gordon C. C. Yang, Hong-Ping Lin |
| 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-0827108-150304 |
| Rights | withheld, Copyright information available at source archive |
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