Reduction of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans by Chemical Inhibition and Physisorption from a Municipal Solid Waste Incineration System

Abstract

This study was based on a full-scale (450 t/d) circulating fluidized bed (CFB) municipal solid waste incinerator (MSWI), focusing on the reduction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in flue gas and ash affected by S-, P-, and N-containing inhibitors and a fabric filter with active carbon injection (FF + ACI). The inhibitors injection coupled with FF + ACI effectively reduced total PCDD/F by 98.81% and toxic PCDD/F by 99.32% from flue gas, ensuring PCDD/F emissions lower than the national standard (0.1 ng I-TEQ/Nm3). The inhibitors reduced 43.51% PCDD/F in flue gas and 34.88% PCDD/F in ash, and the inhibition effect on PCDD/F formation pathways follows the order of chlorophenol (CP) route formation > de novo synthesis > dibenzo-p-dioxin and dibenzofuran (DD/F) chlorination. Sulfonating phenolic precursors is an important inhibition pathway of PCDD/F in this study. FF + ACI could effectively remove the total concentration of PCDD/F in flue gas by 97.58% and 97.92% with and without inhibitors injection, respectively, and the removal efficiencies on toxic PCDD/F are both 98.67% for two conditions. Additionally, FF + ACI had a weaker RE on congeners with two or more groups of chlorine substituents at the meta-position than those with fewer groups. The results will pave the way for further industrial optimized designs of air pollution control devices to control the PCDD/F emission from MSWI.