| Summary: | 碩士 === 大仁科技大學 === 環境管理研究所 === 95 === In this study, a denudation wastewater from CD plate recycling process was diluted in concentrations of 100 mg-COD/L as adsorbate during a continuous isotherm adsorption of the activated carbon column. Then, thermal regeneration of the saturated activated carbons was carried out under a microwave-induced heating process. The adsorption capacity of the virgin carbon made of bituminous coal (B-AC) was measured ca. 0.5-2.2% lower than that of the virgin carbon made of coconut shell (C-AC). It may be due to various functional groups and amounts are on structures of them. The adsorption capacity of either B-AC or C-AC was also increasing with an increasing concentration of the adsorbate via batch equilibrium adsorption tests. This implies that a multi-layers adsorption may be occurred between the adsorbate and surfaces of the activated carbons. Freundlish coefficients of K and n were calculated to be 10.0786 and 2.8563 with C-AC as well as to be 13.0377 and 3.4916 with B-AC.
The adsorption capacities of the regenerated fixed-bed with either B-AC or C-AC increased with an increase of output power of microwave (PMW), gas hourly space velocity (GHSV) of carrier gas, and heating time period (tMW). The regeneration efficiency of the C-AC fixed-bed was calculated highly up to 111.53% and 114.45%, respectively, as a result of the microwave-induced regeneration process was prolonged to either 15 or 18 min. Both the adsorbate and other substances previously adsorbed onto either C-AC or B-AC may be almost desorbed during the microwave regeneration runs. The regenerated fixed-bed of either B-AC or C-AC was found with a higher adsorption capacity than that of the ones filled either virgin B-AC or virgin C-AC. In addition, adsorption capacity of both the regenerated fixed-beds would reach a maximum value at the sixth adsorption/regeneration cycle, and then decreased approximately to a constant value. This means that the field-spent carbon regenerated by microwave-induced heating method can be reused more times than the ones after traditional thermal regeneration runs. The advantage of microwave-induced heating technology is not only can significantly reduce operation time during the regeneration of activated carbon process, but also can save cost of buying virgin carbon and disposal of spent carbon. The optimum conditions for the carbon fixed-bed regeneration process were found for 15 min under microwave energy at a power level of 427.8 W as well as the inert gas at a GHSV of 287.9 h1.
Time period for the microwave-induced regeneration of either C-AC or B-AC fixed-bed is recommended for 25 min if water of the carbons is removed by the gravity only. The energy cost of the microwave-induced regeneration runs is calculated approximately 7% of the regeneration runs carried out by heating with a traditional electrical furnace. Furthermore, cost of carrier gas consumed for the microwave-induced regeneration runs is about 30% of the electrical furnace heating runs.
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