Putting Plastics to Use A Second Time around Researchers See Increased Market for Recycling, but Problems Remain

Article excerpt

OF the 180 million tons of solid waste Americans throw into landfills each year, about 20 percent, by volume, is plastics. About 8 percent of the total volume of garbage is plastic packaging, everything from soda pop bottles to hamburger containers.

That 8 percent holds the greatest hope for recycling, and the collection and reuse of many plastics have significantly increased in recent years. But there's still a huge amount of room for improvement. About 6 percent of the total plastics used in packaging was recycled in 1993, according to the Plastics Institute of America.

A reason more plastics have not been recycled is economics: Making new plastic from recycled bottles and cartons has usually been more expensive than making it from the basic raw material, petroleum and natural gas. So the stuff has gone into landfills instead.

Thorny technical problems, such as separating the various kinds of plastics that get into the waste stream, pose another hurdle. A key problem, says Howard Herzog, a senior research engineer at Massachusetts Institute of Technology (MIT) in Cambridge, Mass., is the need for "very pure feed stock" to meet the specifications for many plastic products. Mr. Herzog served as an adviser to student researchers who recently wrote a "working paper" on the problems of plastics recycling.

Unlike glass bottles, plastic containers are not washed and reused, but melted down. The federal government sets very high standards for the ingredients that go into food containers, and much of the melted-down waste plastic can't meet those standards.

Only a relatively small percentage of used soft-drink containers, for instance, is recycled into new bottles, says Bill Sacks, executive director of the Plastics Institute of America. Most such containers, which carry the recycling code "1" and are made of polyethylene terephthalate (PET), get melted down and turned into carpet fiber, fill for insulated apparel, and various other nonfood-related items, Mr. Sacks says. Plastic recycling rises

A relatively high 35 to 40 percent of the PET containers sold are recycled. The heavier plastic "base cups" that encase the bottom of large soda bottles are also recycled at a relatively high rate, around 15 percent. They're made of high density polyethylene (HDPE), as are many other common containers, such as milk bottles, and carry the recycling number "2." They can be recycled into such products as irrigation drainage tiles or sheet plastic. But these categories are the exceptions, according to the working paper produced by MIT researchers. …