Effects of municipal solid waste component on gasification performance and chromium partitioning behavior under CO2 atmosphere

Municipal solid waste (MSW) consists of complex components with high chromium (Cr) content, for which CO2 gasification is an effective MSW treatment technology. Herein, the main components of mixed MSW, including kitchen waste (KW), paper, printed circuit board (PCB), plastic, pine wood (PW) and rubber, have been separated. At 700-900 degrees C, CO2 gasification performance and Cr partitioning behavior of MSW components as well as mixed MSW are investigated to determine the role of each component. KW exhibits a significant catalytic effect on rubber decomposition at 700 degrees C, which increases the CO yield of mixed MSW by 0.11 Nm(3)/kg. However, further increases in temperature can weaken this catalytic effect. According to the linear superposition parameter of MSW components, the Cr content in mixed MSW gasification ash slightly increased with increasing temperature, while the Cr enrichment ratio decreased. In fact, both quantities tend to increase with 57.36 -> 132.71 mg/kg and 41.61 % -> 62.21 %, respectively. Paper, plastic and PW gasification ash can adsorb Cr released from KW, PCB and rubber; although KW induces higher amounts of toxic Cr(VI), increasing temperature reduces its content. In addition, KW and PW contribute to the formation of glass phase, which immobilizes Cr in non-bioavailable forms. Consequently, KW, paper and plastic are the main components of mixed MSW (83.33 wt%) and the main contributors to gasification performance (>78 %), while PCB and rubber mainly result in Cr environmental risk (>61 %). Under CO2 gasification, unclassified MSW can still achieve high energy utilization and reduce Cr pollution.