Performance evaluation of urea injection on the emission reduction of dioxins and furans in a commercial municipal solid waste incinerator

Abstract

Polychlorinated dibenzo-p-furans and dioxins (PCDD/Fs) that pose a great threat to human health are commonly found during the incineration of municipal solid waste. In this study, industrial urea was injected into a commercial MSW incinerator flue gas to evaluate the suppression performances of PCDD/Fs, and the possible inhibition mechanisms were proposed. The results show that the use of urea dramatically reduced the PCDD/Fs emission concentration from 8.87 to 0.63ng/Nm3, along with a significant decrease in the I-TEQ value (0.26 → 0.047ng I-TEQ/Nm3), below the Chinese national standard of 0.1ng I-TEQ/Nm3. The emission reduction cost of the industrial urea was over 41 % lower than that of using activated carbon. Urea molecule poisoned the metal ions, thus seriously inhibiting the de novo synthesis of PCDD/Fs. Furthermore, the decomposition products of urea reduced the concentration of HCl in the flue gas, thereby reducing the formation of Cl2 and hindering the chlorination reaction, which was identified from the reduction of chlorination degree and lower distribution of high-chlorinated PCDD/Fs. This research provided some practice basis and experience to reduce the emission of PCDD/Fs from municipal solid waste incineration for future commercial promotion and application.