Environmental Engineering Reference
In-Depth Information
of generated PET. For example, in North Carolina, recovered PET bottles are the
primary source of PET recovery. Some municipalities in North Carolina stopped
or slowed collection efforts due to low market prices. Most of the recovered PET
material was recovered through local government programs. The contribution of
the private sector in North Carolina for PET bottles recovery was very small
(NCDENR 1998). Price and capacity are the main elements of PET market
dynamics. They are very sensitive to fluctuations in virgin and off-spec markets.
These fluctuations are directly related to international economic conditions and
supply/demand balances. End users for recovered PET may include engineered
resins, fiber, food and beverage containers, nonfood containers, sheet, film, and
strapping.
4.7.2 HDPE Plastic
High-density polyethylene (HDPE) is obtained by polymerizing ethylene gas.
The most common item that is manufactured from HDPE is milk jugs. Most of
the current recovered HDPE is accomplished through local government collection
programs. The most common form of recovered of HDPE is blow-molded bottles
and HPDE grocery bags. The national generation of HDPE in MSW was 6.04
million tons in 2006. Out of these, 0.58 million tons were recovered and 5.46
million tons were discarded (U.S. EPA 2007). Milk and water bottles represent
more than 10 percent of the PET generated (0.71 million tons) in the MSW.
About 31 percent (0.22 million tons) of these bottles are recovered.
4.8
Steel Cans
According to U.S. EPA (2007), 2.75 million tons of steel packaging were gen-
erated in MSW in 2006. Out of those, 1.74 million tons, or 63.3 percent were
recovered and 1.01 million tons were discarded. Food and other steel cans rep-
resent more than 90 percent of the steel package generated (2.51 million tons) in
the MSW. The generation and recovery amounts are directly related to population
growth.
It should be noted that steel cans represent a small portion, less than 20 per-
cent, of the total ferrous metals (14.2 million tons) in MSW. Junked automobiles,
demolished structures, worn-out railroad cars and tracks, appliances, and machin-
ery are the major sources of obsolete scrap. The decrease in the percentage of the
recycled steel is due to the increase in the production of durable steel products.
The value of steel scrap is affected by the demand for finished products. As the
demand expands, the need for more scrap steel will grow. The demand for steel
is typically affected by the demand for cars. Efforts are underway to enhance
the growth of other steel markets, and new technologies in steel production have
increased the dependence on scrap. Nationally, the demand for steel can scrap is
always more than the supply. The total demand for all steel scrap is much more
than the part supplied through steel can recycling.
 
 
Search WWH ::




Custom Search