Model development for optimizing emissions and carbon credit from integrated waste and wastewater management.

Abstract

This study examines the variability in estimating aggregated and disaggregated emissions from the solid waste sector using worldwide adopted methods for country accounting, life cycle assessment modelling, and corporate reporting. Disaggregation of emissions was conducted by source (waste management process from collection to disposal), gas (CO2, CH4, and N2O) or type (direct and indirect) to identify processes contributing most to the potential variability in estimated emissions. While similar operational data were introduced in all methods, significant variability in estimated emissions were evident across methods. The variability in aggregated emissions ranged from 3 to 65percent that dropped to 2 and 17percent when default parameters were standardized across methods. At the disaggregated level, a wider variability was discerned reaching several folds depending on the source, gas or type of emissions. The observed variability can be attributed to differences between methods in approaches and default parameters. These differences can affect emissions mitigation measures - reduction targets or influence investments in carbon credit to meet countries’ Nationally Determined Contributions under the Paris Agreement. This research presents a novel comprehensive model developed to assess the carbon footprint of integrated solid waste management systems including the diversion at source of the food waste component into the wastewater-sludge management systems using household food waste disposers. In addition to the current state of practice in developed economies, the model includes emissions from waste management processes still practiced in developing economies (such as open dumping, open burning, poorly operated landfills with flaring systems and auxiliary fuel needed to satisfy the low heating value (LHV) during incineration) commonly not considered in most life cycle assessment (LCA)-based models. It can disaggregate emissions by source (from collection to final disposal), or type (direct-operating, indirect-upstream