Evaluation of organic waste diversion alternatives for greenhouse gas reduction

• Published in: Resources, conservation and recycling conservation and recycling, 2012-03, Vol.60, p.1-9
• Main Authors: Yoshida, Hiroko, Gable, Joshua J., Park, Jae K.
• Format: Article
• Language: English
• Subjects: anaerobic digesters; Anaerobic digestion; Applied sciences; Biological and medical sciences; Biotechnology; capital; Co-digestion; energy recovery; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; General treatment and storage processes; Global warming; Greenhouse gas accounting; greenhouse gas emissions; greenhouse gases; industrial wastes; landfills; life cycle assessment; methane; Methods. Procedures. Technologies; Organic fraction of municipal solid waste; Organic waste diversion; organic wastes; Other industrial wastes. Sewage sludge; Others; outreach; Pollution; recycling; sewage sludge; Various methods and equipments; Waste-to-energy; Wastes; wastewater treatment; Wastewaters; Water treatment and pollution; windrow composting; yard wastes; zero wastes
• ISSN: 0921-3449; 1879-0658
• DOI: 10.1016/j.resconrec.2011.11.011

► We conducted a greenhouse gas emission analysis for current and alternative organic waste management practices. ► The analysis includes the necessary modifications of a collection scheme for source separation. ► Among the options considered, co-digestion of organic waste at the local wastewater treatment plant was found most favorable from both environmental and economic perspectives. ► Public participation, efficiency of collection, and waste composition affected the outcome of study. ► Local partnership between utilities is necessary for successful implementation. Greenhouse gas (GHG) emission analysis was performed for current and proposed organic waste management practices in the City of Madison, Wisconsin, United States of America (USA). Aiming for the long-term goal of zero waste, the City of Madison has been looking into an opportunity to divert its organic waste from its landfill. Previous studies suggested that organic waste diversion could result in a GHG emission reduction: Alternative treatment of organic waste would reduce GHG emissions through avoidance of landfill methane emission, nutrient replacement, and energy recovery when anaerobic digestion technologies are employed. However, organic waste diversion requires modification of collection practices and additions to the collection fleet. This would increase the GHG emissions and there is a need to balance emission reductions and the additional costs associated with a new organic waste diversion program. Collection practices are also important for the success of such a project, as it accounts for 83% of current operational cost for managing organic waste. The GHG emissions were quantified using the Life Cycle Assessment (LCA) approach. The current practice of composting of yard waste and direct disposal of other fractions of organic waste into the landfill were estimated to emit 224kgCO2-eq./ton of GHG. In contrast with the current practice, four alternatives were assessed in this study: windrow composting, high-solids anaerobic digestion, co-digestion at a large scale industrial waste anaerobic digester facility, and co-digestion at the local wastewater treatment plant. The results show that the co-digestion of source-separated organic waste would achieve the highest GHG emission reduction among the alternatives considered. The results were as follows: 81.5kgCO2-eq./ton for windrow composting; −46.0kgCO2-eq./ton for a high solids anaerobic digester; −156kgCO2-eq./ton for co-digestion wit