Dioxin and Furan Emissions from Gasification

Abstract

PCDD/Fs are a 75-member family of toxic chemicals that include congeners (members) that have serious health effects including congeners that are classified group 1 carcinogens, endocrine disruptors and weakening or damage to the immune system. Municipal solid waste (MSW) incinerations had historically been implicated as the major source of PCDD/Fs distributed by air. As a result of awareness and legislation most European MSW incinerators were either shut down or equipped with modern air pollution control systems necessary to achieve MSW incineration with PCDD/F emissions within regulatory limits set by national and international laws (typically <0.1 ng TEQ/Nm3). There is a common belief that gasification of waste and/or biomass, unlike incineration, inherently and always achieve emission below regulatory and detectable limits. However, a review of the literature suggests that the belief that the substitution of incineration with gasification would always, or necessarily, reduce PCDD/Fs emissions to acceptable levels is overly simplistic. This chapter discusses the mechanisms of PCDD/Fs formation, the operational measures and parameter ranges that can be controlled during gasification to minimize PCDD/Fs formation, and methods for post-formation PCDD/F removal are reviewed. The purpose of this chapter is to assist researchers and practitioners in formulating waste management policies and strategies, and in conducting relevant research and environmental impact studies.