HDPE Recycling
HDPE bottle recycling in the U.S. exceeds PET bottle recycling both in terms of total amount. In 2002, 364 thousand tones (800 million pounds) of HDPE bottles were recycled, up from 341 thousand tones (750 million lbs) in 2001. The recycling rate increased t0 24.2% in 2002 from 23.2 percent in 2001. Growth in tonnage and in recycling rate has been slow in the past several years, but HDPE recycling has not experienced the declines that have hit PET. The recycling rate is generally higher for unpigmented containers such as milk and water bottles than for pigmented containers. However, that gap has narrowed. In 2002, natural HDPE bottles had a recycling rateof 26.1%, down from 27.6% in 2001, while the rate for pigmented HDPE bottles increased from 19.3% in 2001 t0 22.4%. Unpigmented containers sell for a price premium because they are suited for a wider variety of end uses. The value of pigmented bottles is increased by color separation.
In addition to bottles, there is some recycling of other HDPE containers and of merchandise sacks. The recycling rate in the HDPE bags, sacks & wraps category was 3.9% for a total of 27,000 tonnes in 2001. The overall recycling rate for HDPE packaging was 8.7%.
The largest use for recycled HDPE bottles is in the manufacture of new non-food HDPE containers. For a number of years, laundry detergent bottles and containers for similar products have had a three-layer structure with a core of recycled HDPE plus bottle regrind. Many motor oil bottles are made with a blend of recycled and virgin HDPE.Pallets & lumber, drainage pipe, and film are also significant uses, as can be seen. Drainage pipe was the first large-scale use for recycled milk bottles. Pipe manufacturers now use considerable amounts of pigmented HDPE bottles. Since most of the pipes are black, mixed colors do not create any problems. However, this stream contains relatively high levels of polypropylene contamination, compared with the unpigmented HDPE stream. The PP is mostly from caps that were left on the bottles, and it limits the proportions of this feedstock that can be used by at least some manufacturers. The film market consists primarily of garbage bags and merchandise sacks.
Caps also present some color contamination problems in the unpigmented HDPE stream. While consumers are requested to remove the caps before turning the bottles in for recycling, they do not always comply.The typical processing procedure for recycled HDPE does not permit separation of the PP and HDPE, since both are lighter than water. The presence of a relatively small amount of cap material can darken the reprocessed HDPE enough to lower its value by 2 t0 7 cents per kilogram.
LDPE Recycling
Recycling of LDPE packaging in the U.S. is primarily directed at stretch wrap, collected from businesses, and at merchandise sacks, collected from consumers through drop-off sites located at stores. There is very little collection of plastic bags at curbside in the U.S., though there are fairly widespread curbside bag collection programs in Ontario, Canada, and to a lesser extent in Quebec. These programs, sponsored b the Plastic Film Manufacturers Association of Canada and the Environment and Plastics Institute of Canada (EPIC) have been operating for several years. EPIC published “The Best Practices Guide for the Collection and Handling of Polyethylene Plastic Bags and Film in Municipal Curbside Recycling Programs" in 1998. This document provides valuable step-by-step guides for implementing what they have found to be the "best practices" for such systems. These programs typically collect HDPE bags as well as the more common LDPE bags. Often there is no practical way for the consumer to tell the two material apart. Although HDPE and LDPE are not totally compatible resins, despite being produced from the same monomer, the resulting blends maintain useful properties.
There is very little recycling of LDPE containers, largely because there is little use Of LDPE containers in packaging, insufficient to justify dedicated recycling programs. Some LDPE containers are collected in the relatively few curbside programs that accept all types of plastic containers, but the quantity is negligible. EPA reports that the overall U.S. recycling rate for LDPE packaging was 2.6% in 2001, for a total of136,000 tonnes. The American Plastics Council reports a 0.6% recycling rate for LDPE/LLDPE bottles in 2002, up from 0.5%.
The major market for recycled LDPE is the manufacture of trash bags. Some recycled LDPE is also used in manufacture of plastic lumber, merchandise bags, bubble wrap, plastic lumber, housewares, and other products.