ASSESSING GREENHOUSE GASES FROM A TRIPLE BOTTOM LINE APPROACH

摘要

The St. Louis Metropolitan Sewer District (MSD) operates seven wastewater treatmentfacilities ranging in size from 40 mgd average daily flow (ADF), to over 120 mgd ADF.MSD’s biosolids disposal options have included land application, composting,landfilling, and landfill disposal of incinerated ash. In 2009, MSD faced the dauntingprospect of needing to undertake major structural renovations to the incineration facilitiesat its two largest treatment plants at a time when pending regulatory revisions to theClean Air Act (CAA) were going to significantly impact the continued use of existingmultiple hearth furnace (MHF) incineration technology. As part of a comprehensiveassessment of its entire biosolids system, MSD undertook a triple-bottom line assessmentthat also incorporated the impact greenhouse gas (GHG) production would have on itsfuture decision-making process, including opportunities to partner with energy utilities aspart of its future operations. This paper addresses the overall GHG evaluation process,the assessment of GHG emissions for various alternatives, and the reconciliation ofGHG’s as part of the triple-bottom line (TBL) evaluation and selection process at theDistrict’s largest facility.