Co-treatment of hazardous wastes by the thermal plasma to produce an effective catalyst

Abstract

In the past two years, a pilot-scale plasma gasification was carried out. With the help of this project, we investigated the possibility to recycle plasma gasification-derived slag as an effective catalyst by adjusting co-treatment ratio between medical waste and fly ash. As a result, when the co-treatment ratio of fly ash increased, the derived slag showed a bigger content of transition metal, together with a higher activity for selective catalytic reduction of nitric oxide. Specifically, the co-treatment slag with a best activity removed 64.4% of nitric oxide (1000 ppm) at 250 °C, 23.5% higher than the slag from single treatment of medical waste. On the other hand, almost all zinc (15.85–16.99 mg/g) and plumbum (0.72–1.16 mg/g) from raw materials were enriched in the secondary fly ash. Hence, if the secondary fly ash was treated by the plasma gasification again, these heavy metals would obtain further enrichments, which transformed the secondary fly ash into a potential resource for metallurgy. The main result of this work indicated a proper co-treatment of hazardous wastes by the plasma gasification produced high-value-added products. The plasma gasification was a “zero discharge” technology for the treatment and recycle of various hazardous wastes.