Additional organics processing capacity is needed to handle an increased emphasis on organics diversion in the U.S.
In the 1967 movie “The Graduate” Benjamin Braddock, a recent college graduate, is told the future is plastics. Fast forward to 2015, and that same college graduate would be told the future is organics.
Organics are playing a progressively more important role in the solid waste industry, and this trend will continue for years to come.
This article presents information on the contribution of organics in the municipal solid waste (MSW) stream, the drivers behind organics collection and processing, the changing role of organics in collection and processing, and the future role of organics in energy-from-waste (EFW) technologies.
What are organics?
Typically when we think of organics, we think of yard trimmings and food scraps. Other organic components of the waste stream include paper, manure, textiles, rubber, diapers and carpet. For the most part, food scraps and yard trimmings are the materials that are available, accessible and able to be processed for composting and energy production.
According to the U.S. Environmental Protection Agency (EPA) Waste Characterization Study, as shown in the pie chart to the left, food comprises 21 percent of the disposed municipal waste stream, with yard trimmings making up 9 percent.
Recent statewide studies also have identified high percentages of organics in the waste stream. A comparison of organics waste composition in MSW from eight recent statewide waste composition studies shows the percent of yard trimmings in the disposed waste stream ranges from 3 to 10 percent, with an average of 5 percent in this sample. Food scraps composition ranges from 10 to 22 percent, averaging 15 percent in this sample of states.
A number of drivers are creating the incentive to divert more organics from landfills, including:
- disposal bans for yard trimmings and food scraps;
- statewide diversion mandates/goals;
- growing public and political call for renewable energy;
- climate protection regulations;
- recycling and organic diversion initiatives;
- more advanced technologies; and
- subsidy and grant availability;
The following are a few examples of state initiatives that are fueling the demand for organics diversion and processing:
- Massachusetts: Beginning Oct. 1, 2014, commercial entities that generate more than 1 ton of food waste per week must divert waste from landfills/waste-to-energy (WTE) facilities.
- Connecticut: Beginning Jan. 1, 2014, commercial entities that generate more than 2 tons of food waste per week must divert waste from landfills/WTE facilities if a permitted organics processing facility is located within 20 miles of the generator.
- Vermont: Beginning July 1, 2014, entities that generate more than 2 tons of food waste per week must divert waste from landfills/WTE facilities.
- Rhode Island: Beginning Jan. 1, 2016, commercial entities that generate more than 2 tons of food waste per week must divert waste from landfills/WTE facilities, if a permitted organics processing facility is located within 15 miles of the generator.
- California: By 2016, each jurisdiction must implement an organic waste recycling program. By April 1, 2016, businesses that generate 8 cubic yards of organic waste per week must arrange for recycling services.
A recent study by the Institute for Local Self Reliance (ILSR), Washington, collected data on the types and numbers of composting facilities operating in the U.S. (Institute for Local Self-Reliance, State of Composting in the U.S., 2012). This study revealed that although there are more than 4,000 composting facilities in the U.S., the majority of which (70 percent) compost only yard trimmings. About 350 facilities compost food scraps and many facilities operate on site. For example, institutions, such as universities, prisons, etc., compost yard trimmings and some food scraps.
According to the “U.S. EPA Municipal Solid Waste Generation, Recycling and Disposal in the United States: Facts and Figures for 2012,” 34 million tons of yard trimmings were generated, with approximately 20 million tons, or nearly 60 percent, recovered. However, an estimated 36 million tons of food scraps were generated in 2012, and of that, 1.74 million tons, or less than 5 percent, were recovered.
The future of organics processing
To achieve higher levels of recovery, more processing capacity is needed, particularly for food scraps. There is potential to add food scraps to some yard trimming composting facilities, although a number of challenges must be overcome, including regulatory barriers, permitting and siting hurdles and public perception and acceptance.
Interest in the development of anaerobic digesters for processing food scraps and yard trimmings is growing in the U.S. Europe is still the global leader in this area, particularly Germany. It is estimated that if half of this organic waste were anaerobically digested, enough electricity would be generated to power 2.5 million homes each year.
The American Biogas Council (ABC), Washington, projects that up to 12,000 potential sites will be ready for development and predicts that renewable biogas could displace as much as 10 to 15 percent of fossil-fuel-based natural gas consumption by 2023.
In California, there are a number of anaerobic digestion (AD) projects operating, as well as others in various stages of construction, commissioning, permitting and analysis. Currently operating facilities include wet thermophilic, mesophilic, dry thermophilic and high-solids facilities, and they are handling feedstocks that vary from biosolids, fats, oils, grease and food scraps to yard trimmings and food scraps.
In Marina, California, the Monterey Regional Waste Management District (MRWMD) has operated a pilot research AD facility since March 2013. The facility utilizes the SmartFerm AD technology, which is a dry, thermophilic process, and is capable of processing 5,000 tons of yard trimmings (30 percent) and food scraps (70 percent) per year. This system produced more than 308,000 kilowatt hours (kwh) of electricity in the first six months, or approximately 44,000 kwh per month.
In Perris, California, CR&R Environmental Services, a municipal waste and recycling services provider, is presently constructing Phase 1 of its AD facility, using the Eisenmann technology — a dry, plug-and-flow, continuous feed process. The planned facility is permitted to process more than 80,000 tons of organic waste per year in Phase 1 and to expand to process more than 300,000 tons per year in three additional phases, making it one of the largest AD projects in the U.S. Expanding on its state-of-the-art recycling processes, CR&R will integrate the new plant into its existing operations. Feed for the new system will include green yard waste and food waste. Overall, the AD plant is projected to generate approximately 1 million diesel gallon equivalents (DGE) of compressed natural gas (CNG) per year.
Organics will continue to comprise a significant portion of the waste generated in the U.S. Diversion of this material from landfills will increase as state mandates, public acceptance and demand for green energy increases. Existing capacity to process organics is not adequate to handle the types and quantities of materials generated. Improvements at existing composting operations and advancements in new technologies will meet the capacity needs, coupled with regulatory changes, financial investments and political support.
Michelle Leonard, vice president of SCS Engineers, directs SCS’ sustainable materials management practice in California and is a recognized leader in the field of solid waste management and recycling. She has spent all of her professional career in environmental consulting with an emphasis in solid waste management planning and is currently the international board vice president of the Solid Waste Association of North America (SWANA). A version of this article first appeared in the January/February 2015 issue of Recycling Today’s sister publication Renewable Energy from Waste.