The thermal degradation and soil recovery of thermal treatment of field-weathered decabrominated diphenyl ether-contaminated soil

Abstract

A farm at Taoyuan in Taiwan was highly contaminated with decabrominated diphenyl ether (BDE-209), a widely used commercial brominated flame retardant and persistent in the environment, more than 10 years. Since crops are able to absorb and accumulate BDE-209 from soils in our previous research, posing a hazardous risk for humans, it is essential to develop a practical method of soil treatment. Thermal treatment was studied among different approaches. In our previous study (Ko et al., 2022), we found that heating to 450 °C for 30 min achieved a complete removal of BDE-209 in soil. However, the high temperature significantly decreased the original soil organic matter (SOM) from 2.47% to 0.27%, altering the soil texture, damaging microbial biomass, and thus affecting the revegetation after the thermal treatment. Sugarcane bagasse, a common agricultural residue, served as an amendment to restore soil fertility. Current results indicate that 2.5% bagasse can improve the SOM in soil by up to 2.73% and restore its bacterial composition, making the plant growth conditions similar to those of the untreated contaminated soil. In light of the high removal efficiency provided by the 450°C-thermal treatment and the high recovery efficiency of sugarcane bagasse, the strategy presented in this study serves to be a promising method for sustainable remediation.