亚洲国际在线 by Dr. Jeffrey Morris, Dr. Enzo Favoino, Eric Lombardi and Kate Bailey
Zero Waste communities push for ever-higher resource recovery rates through a strong emphasis on source-separated recycling and composting, waste reduction and reuse programs. While leading communities continue to progress toward 90% recovery and better, there can still remain many thousands of tons of mixed-waste residuals (a.k.a. “leftovers”) that need to be disposed of, most commonly in landfills. The question before us and addressed in this study is: “What is the best method for managing our residuals in order to reduce the harm and risks to public health and our environment?” To answer this question we took the residual waste from a leading recycling and composting community, Seattle, Washington, and ran it through eight different residual management scenarios, based on the leading technologies in the marketplace today:
1. Landfill with landfill-gas-to-energy (LFGTE) with three different assumptions for gas collection efficiencies;
2. Waste-to-energy followed by landfilling (WTE-to-landfill) as practiced today by leading WTE companies as mass burn incineration;
3. Mechanical Recovery, Biological Treatment followed by landfilling (MRBT-to-landfill) with two different assumptions for therecovery of recyclables and two different assumptions for gas collection efficiencies.
We then used the Measuring Environmental Benefits Calculator (MEBCalcTM), created by Dr. Jeffrey Morris, to assess each leftovers management scenario across seven lifecycle environmental impacts: climate change, acidification, eutrophication, respiratory diseases, non-cancers, cancers, and ecotoxicity. The environmental impacts are caused by the pollution emitted from the various waste management activities used to handle discarded products, packaging and other materials for recycling, composting or disposal.
The study found MRBT-to-landfill had the lowest overall environmental and human health impacts of all the disposal technologies. It is reasonable to conclude that the MRBT option is not only the best environmental practice for managing residuals, but is also the best community strategic option as well.
MEBCalc™ (Measuring the Environmental Benefits Calculator) is Sound Resource Management’s proprietary software for computing the environmental footprint of a community’s municipal solid waste (MSW) management system, from collection through final disposition of each discarded product or packaging material. Environmental impacts covered in the footprint include climate change, public health (respiratory disease, cancer, and toxicity), ecosystem toxicity, waterway nutrification, and acid rain.