What do you need to know about recycled glass?

Recycling glass is one of the environmentally friendly methods of waste disposal supported by the solid waste management industry. Glass is used widely to package food products as well as in many other household items. In 2010, approximately 25 billion glass containers were made in the United States. Close to 80 percent were glass beverage containers and almost three-quarters were glass beer bottles. The remaining 20 percent were mostly glass food containers. Another five billion glass bottles are imported. Most of these are green-hued glass wine and glass beer bottles. Glass manufacturers depend on crushed recycled glass or cullet to make new glass products. Recycled glass is less expensive for glass manufacturers than raw materials, and saves energy for a greener environment.

Glass containers are made from sand, limestone, soda ash, cullet (crushed glass bottles), and various additives, including those used to color brown, green or blue bottles. About half of the glass bottles produced in the United States are clear (also known as flint) bottles, followed closely by brown bottles. Most remaining glass bottles are green with a small amount of blue or other colors.

Glass container use in the United States increased by 4.7 million tons between 1960 and 2005. However, the glass container market share of MSW declined in the same time period by 37 percent as lightweight aluminum and plastic containers replaced heavier glass bottles. In 2010, Americans generated 9.36 million tons of glass into the waste stream; about 33.4 percent of it was recovered for recycling. Glass bottles and jars are the most commonly recycled glass. (Some types of glass cannot be recycled, such as light bulbs, ceramics, glass mirrors, window glass and ovenware.)

Glass recycling is important for reducing overall volume in landfills as well as for saving energy and reducing air emissions. Unlike with paper, burning glass in waste-to-energy plants is not a good alternative to recycling, because glass does not provide any heat energy for making steam or electricity. And glass can be recycled over and over again, with no loss in quality or purity. Recycled glass from containers is made into new glass jars and bottles, fiberglass insulation, kitchen tiles and concrete pavement.

Today, most glass manufacturers rely on a steady supply of recycled glass (crushed glass known as "cullet") to supplement raw materials. To make glass, manufacturers mix sand, soda ash, limestone, and cullet; heat the mixture to a temperature of 2,600 to 2,800 degrees F; and mold it into the desired shape. Sand is the only material used in greater volumes than cullet to manufacture glass.

Preparing glass containers for recycling is relatively simple. Remove lids and caps, and rinse the containers in water. (Removing labels is unnecessary.) Only glass of the same color is processed together during glass recycling, because once glass has been colored, the color cannot be removed. Most curbside glass recycling is commingled (meaning glass of different colors are collected together), but some drop-off glass recyclers ask you to sort glass by color (clear, green or amber/brown).

Currently, 11 U.S. states—California, Connecticut, Delaware, Hawaii, Iowa, Maine, Massachusetts, Michigan, New York, Oregon and Vermont—offer a small cash refund for turning in glass bottles to drop-off centers. Recycling glass bottles can actually make you money.

Glass Container Municipal Solid Waste Facts:

Generated Glass: 9.36 million tons or 60.6 pounds per person per year.

Recycled Glass: 3.13 million tons, a 33.4 percent recycling rate.

Recycled Glass Content: 26 percent of bottles produced in the United States contain recycled content, and a glass bottle can have up to 70 percent recycled content.

Incinerated Glass or Landfilled Glass:

• 6.23 million tons or 3.8 percent of discarded MSW by weight.
• 5.5 million cubic yards or 1.3 percent of landfilled MSW in 1997.
• Glass is non-combustible and generally forms a slag in incinerators.

Glass Source Reduction:

• Glass bottles now weigh 50 percent less than they did in 1970.
• Substituting plastic or aluminum containers for glass resulted in five million fewer tons of glass in the waste stream in 2000

Recycling Markets

• The majority of recovered glass is made into new glass bottles.
• Fiberglass is the second largest market.
• Other markets including abrasives, “glasphalt” for roads, glass beads for reflective paint and filler in storm and French drains.

(sources: Waste Age, Current Industrial Reports, U.S. Census Bureau, Washington; Glass Packaging Institute, Alexandria, VA; “Measurement Standards and Reporting Guidelines,” National Recycling Coalition; “Municipal Solid Waste in the United States: 2010 Facts and Figures,” Office of Solid Waste, Washington; Scrap Specifications Circular 2007, Institute of Scrap Recycling Industries, Washington; EPA; Energy Information Agency)

Want to learn more?

• Click here to learn about composting.
• Click here to learn about the solid waste management process.
• Click here to learn more about how the solid waste industry facilitates recycling.