| 摘要: | 研究期間：10301~10312;Recently, many sites of soil contamination, such as dioxin-containing eggs in Changhua, hazardous waste dumping in Kaohsiung and soil contaminated by dioxin and mercury in Tainan, are discovered. These issuses have attracted much public concern. Among these cases, the contaminated soil in An-shun site simultaneously contains extremely high concentrations of PCP, PCDD/F and mercury. Different characteristics of these contaminats have caused the difficulty of effective remediation of soil. In 2013, a self-developed continuous pyrolysis system is applied to simultaneously remove PCDD/F, PCP and mercury from contaminated soil of An-shun site. The results indicate that higher than 99% of PCDD/F and PCP removal and 97% of mercury removal are achieved. Operating the system at temperature higher than 600oC, PCDD/F and mercury contents in remediated soil are lower than the limits for declaring hazardous materials (i.e., PCDD/Fs: < 1000 ng-TEQ/kg; mercury: < 20 mg/kg). Air pollution control devices are also developed in the project of 2013. Baghouse, quench tower and 3-layer bead-shape activated carbon adsorption bed are proved to effectively remove PCDD/Fs, PCP and mercury in flue gas. Removal efficiencies of PCDD/Fs, PCP and mercury achieved with the quench tower are 35-48%, 66-70% and 80-90%, respectively. In condensate discharged from the quench tower, mercury droplets are easily seen by eyes. Emission concentrations of three pollutants are lower than the emission limits (PCP: 500 μg/Nm3; PCDD/Fs: 0.1 ng-TEQ/Nm3; mercury: 50 μg/Nm3). However, contaminated soil with medium concentrations is mainly tested in the first-year project. Contaminated soils with relatively high concentrations (64.1 mg-TEQ/kg of PCDD/Fs and 3,370 mg/kg of mercury) will be tested in the second stage (2014). Moreover, PCDD/F- and mercury-containing sludges generated with the quench tower or collected from the contaminated site will also be tested in the 2nd stage. For well removing all mercury including elemental and oxided mercury, a flue gas desulfurization system will be developed and tested in the 2nd stage study. Operating parameters of the pyrolysis system, baghouse, quench tower, flue gas desulfurization and multi-layer adsoption system will be investigated. The results obtained in this study can enhance technique level for remediation of contaminated soil and provide the novel technology for PCDD/F and mercury emission control. |
