Can an Old Multiple Hearth Incinerator Meet the New USEPA Sewage Sludge Incinerator Regulations?

摘要

This paper discusses the improvements made to the multiple hearth incinerator (MHI) at theadvanced water reclamation facility (AWRF) located in Brockton, Massachusetts. The MHI isused for thermal reduction of the residual solids generated at the city’s AWRF. In the past, thecity had encountered operational challenges with the MHI, including high maintenance due toslag and clinker formation, incomplete burning of the solids due to balling of the solids feed, andlimited capacity. In addition, stringent U.S. Environmental Protection Agency (USEPA) sewagesludge incinerator (SSIs) regulations had been proposed that put continued use of the MHI injeopardy.In June 2009, the city authorized CDM Smith to perform a preliminary design and eventually afinal design of upgrades to the MHI. Upgrades to the MHI included installation of a flue gasrecirculation (FGR) system to improve emissions and to reduce slag and clinker formation,replacement of the existing wet scrubber with a multi-venturi scrubber, and significant otherimprovements and repairs to the incinerator. Construction was completed in fall 2010 andemissions compliance testing was conducted on January 21 and 22, 2011.This paper will also discuss the air permitting process with the Massachusetts Department ofEnvironmental Protection (MADEP). MADEP required that air dispersion modeling of theincinerator’s emission limits be conducted. The air modeling demonstrated that the incineratormeets the MADEP’s Allowable Ambient Limits (AALs) and Threshold Effect Exposure Limits(TELs), as well as the National Ambient Air Quality Standards (NAAQS). Final compliancetesting of the incinerator emissions demonstrated that the incinerator met the recently finalizedUSEPA sewage sludge incinerator regulations (40 CFR Part 60, Subpart MMMM).