Air-Polluting Emissions from Pyrolysis Plants: A Systematic Mapping

There is a growing interest in the use of pyrolysis plants for the conversion of solid waste into useful products (e.g., oil, gas, and char) and the analysis of air-polluting emissions associated with such a process is an emerging research field. This study applied a systematic mapping approach to collating, describing, and cataloging available evidence related to the type and level of air pollutants emitted from pyrolysis plants, the factors affecting emissions, and available mitigation strategies that can be adopted to reduce air pollution. The scientific literature indexed in Scopus and Google Scholar, as well as available industry reports, was interrogated to document the evidence. A database comprising 63 studies was synthesized and cataloged from which 25 air pollutants from pyrolysis plants were considered, including volatile organic compounds and persistent organic pollutants. Air pollutant levels varied depending on the scale of the pyrolysis plants, their operating conditions, and the feedstock used. Various technologies, such as wet scrubbers, electrostatic precipitators, and baghouse filters, are available and have been utilized to reduce emissions and comply with the existing EU regulations for waste incineration (2010/75/EU). The systematic mapping identified several knowledge gaps that need to be addressed to inform relevant environmental policymaking, technology development, and the adoption of best practices for the mitigation of emissions from pyrolysis plants.