Keywords:MSW incineration fly ash Heavy metals Volatilization and leaching behavior DC arc plasma CaO -Al 2 O 3 -SiO 2 (CAS) A B S T R A C T Three fly ash samples collected from different waste incinerators were vitrified using a direct current arc plasma furnace at 1250-1400°C. The influence of water-wash extraction and wrapping pretreatment on the volatilization and leaching behavior of heavy metals was investigated. Results showed: After thermal arc plasma treatment, the volume reduction and weight loss of fly ash were in the range of 68.7-82.2% and 23.8-56.7%, respectively. The residual fractions (wt.%) of heavy metals in slag are in the following sequence: Cr < Ni < Cd < Pb < Cu < Zn. Water-washing could reduce the volatilization rate of heavy metals due to some volatile salts removed by washing, while wrapping of fly ash could most effectively resist heavy metals against volatilizing, especially for Zn and Ni. The possible CaO -Al 2 O 3 -SiO 2 (CAS) ratio for successful melting of fly ash is suggested to be CaO in range of 20-48%, Al 2 O 3 in range of 10-15%, and SiO 2 in range of 40-65%. Moreover, toxicity characteristic leaching procedure results showed that the leaching of heavy metals in slags was much lower than the standard limit of toxicity characteristic leaching procedure (TCLP).

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Ventilation corridors in cities can decrease air pollution and alleviate heat island problems but there remains a need to fully assess their effectiveness. Few urban managers have been able to take city-scale approaches to the construction of urban ventilation corridors. This study aimed to introduced the Ventilation Corridor Planning (VCP) model, which is a multi-criteria evaluation method combined with a geographical information system (GIS) to determine where the ventilated environment is most appropriate. Specifically, the VCP model took Bozhou, China as the research object and contained two scales, including mesoscale and local scale. In mesoscale scale, we got three outputs to build urban ventilation corridors, including 1) background wind environment, 2) ventilation potential, 3) heat island intensity. In local scale, we used traditional computational fluid dynamics (CFD) model to verify the impact of VCP criteria. The results revealed that compared with the traditional CFD model, the proposed VCP model has advantages in establishing a comprehensive evaluation standard. In addition, the application of VCP model in macro and micro also enhances the efficiency of ventilation corridor construction. Overall, this study introduced a effective modeling method to urban ventilation corridors planning, and provide a way to study the urban climate.

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