| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 89 === The purpose of this research was to treat PAC sludge of water works, biological treatment sludge, and industrial calcium fluoride chemical sludge by using melting system. By co-melting three kinds of sludge in different ratio, the effect on lowering pouring temperature could be found. On the other hand, the feasibility of using slag for resource recovery was evaluated. The experiments were divided into two parts: (1) Cone test at different ratio : ash composition was conditioned by mixing different kinds of sludge at different ratio, and the influence on lowering pouring temperature at each condition was evaluated. (2) Slag characteristics test and cement motar test: the suitability of using slag as fine aggregate was investigated, and the effect of replacing fine sand in cement motar on compressive strength and workability was studied.
Test results showed that the main composition of water works sludge was SiO2, and the pouring temperature was 1510.0℃ corresponding to the basicity（CaO/SiO2）nearly zero（0.0009）; the main composition of CaF2 sludge was CaF2, and the pouring temperature was 1242.3℃corresponding to the basicity（CaO/SiO2）of 2.703; the main composition of biological sludge was Al2O3, SiO2, and P2O5, and the poring temperature of sludge was 1574.3℃corresponding to the basicity（CaO/SiO2）of 0.243. The lowest temperature was 1146℃ by co-melting three kinds of sludge at different ratio while CaF2 sludge and water works sludge were in the ratio of 6:4. The effect of lowering pouring temperature was about 370℃ for water works sludge, and about 100℃for CaF2 sludge, respectively. The aggregate characteristics test result of 6:4 slag showed that surface dry specific gravity was 2.72, water absorption was 2.26%, and weight per unit volume was 1763kg/cm3, which all meet the CNS standards. Cement motar test result indicated that the workability of slag cement motar decreased with increasing replacement ratio as the slag re-placement ratio was in the range of 0%~50%. Moreover, the 7-day compressive strength reached highest when replacement ratio was 30%; all replacement ratios were better than pure cement motar besides 50%. 28-day compressive strength increased with increasing replacement ratio. 28-day compression strength reached highest when replacement ratio is 40%. In addition, through the evaluation of TCLP, MIP, XRD and SEM, the molten slag replacing part of the natural fine aggregate in the cement motar have the advantages of fixing heavy metals, reducing porosity ratio, better pozzolanic reaction and more hydration product. As a word, the molten slag could be a suitable replacement of the natural fine aggregate.
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