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Mining Glass from the Waste Steam

Waste Glass Processing Center - A Tool for Economic Development

Communities first understood recycling as the collection of materials. In actuality, recycling involves much more than the collection of waste. Recycling is a continual process of Collection - Processing - Transportation - Manufacture - Retail - Consumption. The most important and often the most neglected part of the chain is recycling-related manufacturing.

Recycling related manufacturing offers a community local economic development potential. In fact, manufacturers of recycled products hold a majority of the economic pay-off of the entire recycling process. Adding to the jobs and revenue that recycling collection and processing bring to an area, manufacturers of recycled products provide high-skill industrial jobs and sizable sales revenue to a community. These new factories hold the potential to revitalize a community's industrial sector, while diminishing the local waste stream through buying locally-derived feedstock. A scrap-based manufacturer tends to be a small manufacturing firm who tend to locate near sources of feedstock. Manufacturing of recycled products offers a community the opportunity of self-reliance, as manufacturing feedstock is mined from a local source - the community recycling collection programs.

Of the materials being recycled today, glass is still one of the most difficult to reuse. One of the major problems with glass recycling is the separation of clear and colored glass. To date, there have been very few applications for mixed glass. Glass made up only 6.3% of the total materials recycled in 1994. Of the total glass being recycled approximately 63% is clear glass used for remelting to produce more containers. There are few takers for refuse glass not presorted by color. In 1993, New York City collected 27,000 tons of mixed waste glass and used it to produce glasphalt-90% asphalt and 10% glass. By 1997, however, collection is expected to quadruple. Cullet may end up in landfills. More and more cities are mandating recycle programs. New ordinances in Philadelphia and Chicago require businesses and multifamily dwellings served by private haulers to implement recycling programs. With more and more glass being collected we must find new value-added uses for mixed waste glass.

For the past three years scientists and engineers at the Institute of Materials Processing of Michigan Technological University have been working on applications for the reuse of waste glass. Much of this work was sponsored by the Michigan Department of Environmental Quality. What we discovered was that glass is a natural resource that can be mined from the waste stream and be a valuable commodity to those that recover it.

Waste glass has many uses. Used as an additive in clay, glass lowers the processing temperature and therefore, lowers the costs for producing tiles and bricks. The glass chemically bonds with the clay and makes the product stronger. Used as an additive in plastic, finely ground glass readily replaces the calcium carbonate filler already in use. The glass filler increases the strength and ductility of most plastics tested. When the ground glass was mixed with a ceramic it was inexpensively processed to form finished parts that don't require machining. The glass/ceramic composite material was twice as hard as regular glass. Ground glass was used as an abrasive for water jet cutting. In most applications it performed as well as the garnet normally used. The cost of the garnet is approximately $800 ton. The glass abrasive was produced from waste glass at approximately $10 ton. In sandblasting operations, ground glass, an amorphous silica, can safely replace silica sand, a crystalline silica, and a known carcinogen. There are many uses for ground waste glass, many applications can be found in the local community.

Currently there are approximately 7200 curbside recycling programs in the United States. Curbside recycling now serves an estimated 108 million people These programs are predominantly ran by a municipality in conjunction with a waste hauler. The municipality pays to collect the waste. The cost for collection varies, but in a pilot recycling program in Kalamzoo, MI it was reported that per household curbside cost were approximately $14/yr for monthly service and $36/yr for weekly service. The waste hauler typically pays between $0 and $10 per ton for the material and sells it to an end user for 30$ to 50$ per ton. Recycling, in its present form, is a service provided to residents of the community. However, recycled materials are becoming the raw materials for future products. A recycling program which markets usable raw materials to local industry is beneficial in recouping the cost of recycling as well as helping the local economy prosper and create jobs for the future.

Recycling systems started over the past decade have diverted millions of tons of resources from disposal; however, fluctuations in market prices have meant unreliable revenue for these sources. To offset these market fluctuations communities must work to capture a greater portion of the economic benefits derived from recycling. It is through remanufacturing of recovered material that communities stop viewing solid waste as a disposal burden and seeing it as an economic opportunity.

A Waste Glass Processing Center (WGPC) is a means for local and regional recycling coalitions to bring recycling into the mainstream. The WGPC makes waste glass marketable by providing the collector of the waste glass with the information they need to process and market value-added ground glass. With our years of experience in waste glass research we can design a crushing facility to fit the needs of your community. With a database of waste glass usage we can identify potential customers of waste glass in your community. With a staff of engineers and scientists and our well equipped analytical facilities we can work with the potential users of glass to help them to incorporate waste glass into their present manufacturing process.

With the technical assistance provided through the Institute of Materials Processing of Michigan Technological University community and regional based recycling coalitions, communities, and local industry can pursue grants, loans, and other funding sources with the knowledge that recycled glass is technically feasible and within their financial scope. We would like to partner ourselves with interested parties to make recycling related manufacturing contribute to economic development.

References
  1. United States Environmental Protection Agency. Manufacturing from Recyclables: 24 Case Studies of Successful Enterprises. Manufacturing the Critical Link in the Recycling Chain. Solid Waste and Emergency response EPA530-R-95-001, February 1995.
  2. MSW Factbook, Ver. 3.0, Office of Solid waste, USEPA, Washington, D.C., 1996.
  3. Glass Packaging Institute, 1994 Glass Container Recycling Rate.
  4. ENR/ May 22, 1995
  5. Mandates for Commercial Sector Recycling.BioCycle Dec. 1994: 41-43.
  6. Occupational Safety and Health Administration. Standard Number 1910.1200, Interpretation. Crystalline Silica Considered a Carcinogen under the HCS. 09/20/1988.
  7. Steuteville, Robert,The State of Garbage in America Biocycle April 1995, 54-63.
  8. Evolution of a Recycling System,BioCycle February 1996, 33-36.
  9. The Market Page,Recycling Times 11 June 1996: Vol.8, No. 12.
  10. United States Environmental Protection Agency. Manufacturing from Recyclables: 24 Case Studies of Successful Enterprises. Manufacturing the Critical Link in the Recycling Chain. Solid Waste and Emergency response EPA530-R-95-001, February 1995.


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