Microwave plasma torches for solid waste treatment and vitrification

Conventional thermal plasma technology used in the treatment of solid waste has a high demand for power and a high rate of heat loss during solid waste treatment. We developed a novel approach for treating and vitrifying solid waste with a low-power microwave plasma torch (MPT). Based on theoretical thermodynamic equilibrium calculations, we studied the melting temperature of the residual ash and achieved vitrification of the residual ash with an MPT by adding specified ratios of discarded glass scraps. Thermocouples and a gas analyzer were used to characterize the temperature variations and gas concentrations in the plasma treatment chambers, respectively. An organic elemental analyzer and X-ray fluorescence (XRF) analyses were used to determine the chemical proportions of the solid waste residues. The morphologies of the residues and vitreous material were analyzed using scanning electron microscopy (SEM). The results showed that the microwave plasma treatment process converted 96 wt.% of the solid wastes into nonpolluting gases, leaving a residue of pure carbon and inorganic powder. Through theoretical calculations and experiments, atmospheric MPTs with power levels less than 10 kW were identified as realistic means for treating and vitrifying solid wastes.

Automated summary

A low-power microwave plasma torch (MPT) was used to treat and vitrify solid waste, showing lower power demand and heat loss compared to conventional thermal plasma technology. By adding specified ratios of discarded glass scraps, the residual ash of solid waste can be vitrified. Through experiments, it was found that the microwave plasma treatment process can convert 96 wt.% of solid waste into nonpolluting gases.