It is in society’s economic and environmental interests to expand and standardize plastics waste collection, increase recycling, and explore new applications for plastics waste in infrastructure, says a new report from the National Academies of Sciences, Engineering, and Medicine. Recycled plastics are an underutilized resource, and action from the public sector at the federal, state, and local levels will be needed to improve the plastics waste management system in the U.S., the report says. It also makes specific recommendations for how the U.S. Environmental Protection Agency and U.S. Department of Transportation can promote and sustain a coordinated government response that includes assessments of economically and socially beneficial applications of plastics waste in infrastructure.
Plastics are ubiquitous in modern society, used in everything from consumer goods and packaging to automobile parts and building construction materials. Almost wholly derived from fossil fuels, plastics are often used for short-lived, single-use applications, contributing to a marked rise in plastics waste in recent years. The waste is largely managed through disposal in landfills, incineration, and recycling. Some of it also “leaks” from the management system or is disposed of improperly, ending up as litter on land and in waterways, and then often breaking down into microplastics.
The plastics waste management system in the U.S. is at an early stage of development overall, the report finds. Activities are not well coordinated between the public and private sectors, and research and development for capture, processing, and reuse in consumer products and infrastructure is not far advanced.
Generally, plastic collection, recycling, and reuse is hindered by the large number of types and formulations of plastics; the high cost and complexity of collecting, sorting, and cleaning plastics waste; and other cost and technical challenges associated with processing plastics waste, the report notes. Post-industrial plastics waste ― scraps and off-spec material from plastics manufacturing processes ― is recycled the most, due to its uniform, reliable quality. Post-consumer plastics waste usually has to be separated from other materials, due to dominance of single-stream municipal recycling in the U.S., which leads to contamination issues that can affect the quality of the recycled plastics. Because of these complexities, demand for recycled plastics exceeds the supply of suitable material. Just 10 percent of plastics waste is recycled in the U.S., though rates vary depending on the type of plastic.
“There are isolated examples of successful plastics recycling in the U.S., but overall, there is ample opportunity for higher levels of collection, reprocessing, and reuse of plastics,” said David Dzombak, chair of the committee that wrote the report and Hamerschlag University Professor Emeritus at Carnegie Mellon University. “Determining exactly which pathways to pursue, however, depends on goals, policy, and economics. A coordinated direction for policy and research is key for advancement of plastics recycling in the U.S.”
Using Plastics Waste in Infrastructure
Recycling of plastics for infrastructure applications is a potential means of diverting plastics waste from landfills and litter. Four types of plastics — polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) — have properties that make them conducive to use in infrastructure, such as their suitable melting points and service temperature ranges, chemical resistance, and strength, the report states. These plastics are also the types most collected and recycled from waste streams. However, there are many competing uses for these plastics, such as in bottles, carpet, and clothing.
Infrastructure products using recycled plastics, including asphalt pavement mixes, drainage pipes, and railroad ties, have attracted varying levels of commercial interest, but only drainage pipes have significant demand at present. One of the greatest opportunities for using recycled plastics in infrastructure, in terms of its potential to reduce the amount of plastic waste sent to landfills, may be as a component material in pavements, the report says. Other potential infrastructure uses of note are bike paths, composite utility poles, and highway sound barriers. A range of factors inhibit adoption, however, such as a lack of familiarity, uncertainties over formulation and methods of use, unknowns regarding environmental impacts ― including the potential release of microplastics ― and effects on long-term performance.
The report says DOT should build on existing efforts to support a multiyear field-testing program to assess the environmental and health impacts, overall service life, and effects of plastics additives on the use and recyclability of asphalt pavements. It further recommends that EPA support research and data collection required to understand and evaluate the potential environmental, human health, economic, and performance implications of each new use of recycled plastics.
Improving the Plastics Waste Management System
To improve understanding of the plastics waste management system, EPA should expand the means for tracking and modeling the supply of recycled plastics and the demand that is generated by different applications, with distinctions by quality and polymer type, and accounting for geographic imbalances.
Increasing the overall supply of high-quality recycled plastics that can be used in infrastructure and other applications is also important and will require supportive policies and practices touching every part of the process, from the collection of plastics waste streams and their processing into recycled plastics, to incentives for their reuse, the report finds. Examples include state laws and regulations requiring recycling programs, increasing extended producer responsibility, and federally funded research into new product and materials design.
Market-driven processes that encourage improvements in plastics waste collection and processing in the U.S. could also increase suitable supplies. The report recommends that EPA work to identify specific policies and regulations to support and incentivize plastics recycling, and take steps to encourage and facilitate more collaboration among plastics manufacturers, suppliers, recyclers, industrial, and infrastructure users.
The report also recommends that:
- EPA should lead in strengthening interagency coordination, and work with others including DOT, the U.S. Department of Energy, the National Science Foundation, the National Institute of Standards and Technology, and the Army Corps of Engineers to consider and advise on how each can apply its research and expertise more effectively to plastics waste, recycling, and reuse.
- DOT should inventory current and prospective transportation applications of recycled plastics; work to understand impediments to their development and use; assess waste reduction impacts; and determine how to increase marketplace demand in appropriate infrastructure industries.
The study, undertaken by the Committee on Repurposing Plastics Waste in Infrastructure, was sponsored by the U.S. Department of Transportation and the U.S. Environmental Protection Agency.
The National Academies of Sciences, Engineering, and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, engineering, and medicine. They operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.