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(704a) Sustainable Pathways for Recovering Materials and Energy From Waste

Authors: 
Sengupta, D., Texas A&M Engineering Experiment Station
Smith, R. L., U.S. Environmental Protection Agency
Lee, C. C., U.S. Environmental Protection Agency
Takkellapati, S., U.S. Environmental Protection Agency



Municipal Solid Waste (MSW), more commonly known as trash or garbage, consists of everyday items we use and then throw away, such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries. This comes from our homes, schools, hospitals, and businesses. Waste generated by anthropogenic activity is a great source of carbon, and traditionally, it ends up in the landfill. In 2010, Americans generated about 250 million tons of trash and recycled and composted over 85 million tons of this material, equivalent to a 34.1 percent recycling rate. The purpose of this study is to evaluate various technologies to recover materials and energy from waste going to landfills. We explore two pathways, thermal and biological, to evaluate the recovery of materials from waste.

Thermal techniques of incineration of MSW reduce the volume of waste, and produce heat which can be used to produce steam and electricity. Gasification of MSW produces syngas, an important chemical intermediate, which can be converted into ethanol via catalytic methods and used as vehicle fuel. Biological techniques include separation of the MSW into an organic fraction and subsequent anaerobic digestion for obtaining biogas. Biogas can be cleaned and used for the production of electricity, or upgraded and used for natural gas applications. The organic fraction also resembles cellulosic feedstock, and can be fermented for the production of biofuels. Composting of the organic fraction is a useful way to obtain valuable materials for use in land applications.

Life cycle perspectives are used to evaluate each of these biological and thermal processes to calculate the cost, energy use, environmental releases, and societal issues for sustainability assessment of the process. The results of this research will help communities to decide on a sustainable technology for the treatment of their municipal solid waste. The research will also help them to develop strategies for waste collection, transport, materials and energy recovery, and green job creation in the community.

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