Curbside separations

The degree to which separation is feasible and the degree to which it is necessary most often are dictate by economics although legislative considerations may apply. In some communities, for example, curbside separation of paper, glass, metal, and plastics from other garbage and trash may be mandate by law. We will restrict ourselves here to dealing with a polymer waste stream ostensibly free of most non-polyn c material. 

Curbside Separations by Consumers In the last few years, manufacturers of containers (and some film products) have inttoduced an identification code which enables consumers to segregate products by polymer type [13], Thus, almost every bottle and many bags and cups now bear a recycling triangle with number and letter... 

Generally, recyclables are either coUected at curbside or deposited by consumers at various types of drop-off locations, such as local recycling centers, community service clubs, dealers, and commercial buyback centers. Curbside coUections of recyclables can be accompUshed either in conjunction with the pickup of aU MSW or as a separate activity. Co-coUection systems range from complete commingling of aU waste for later separation at a mixed waste processing facility to transporting essentially source-separated recyclables in the same tmck as MSW. 

Recycling is not the total answer to the soUd waste problem. However, efficiently operated recycling programs can easily divert 35% or more of municipal soUd waste away from disposal. Curbside coUection systems offer the opportunity to coUect the greatest amount of recyclables in the most cost-efficient manner. It is imperative that communities and recyclers operate programs that are glass-friendly and which result in color-separated, contaminant-free material. 

Recycling programs have been remarkably successful in the United States since the 1960s. In 2000, there were curbside "source separation" recycling programs in 9,250 communities. In addition, there were 3,800 separate programs for the collection of yard trimmings. As already noted, resource recovery plants had become somewhat less popular, with just over 100 such plants in operation in 2000. These plants had a total daily capacity of 95,700 short tons (87,000 metric tons) of wastes. 

Some curbside recycling programs allow the commingling of materials that are easily separated to save work for the consumer. For example, steel can easily be separated from aluminum by use of a magnet. 

Curbside recycling programs usually collect comingled materials, as seen here at a Milwaukee site. Plastics, which make up about 85% ofthis pile, must be separated and sorted for recycling. Thomas A. Holme... 

The products are recovered from the MS W stream via curbside collection, separated/ sorted at MRFs, and then cleaned and ground into chips at plastic reclaiming facilities to be remelted into recycled resin pellets. The recycled resin is used, mixed with virgin plastics, in the fabrication of plastic products. Mechanical recycling works best when applied to source-separated streams of waste plastics products. 

At the plastics processor, the baled HDPE containers are usually shredded, washed, and sent through either a float-sink tank or a hydrocyclone to separate heavy contaminants. Air classification may be done prior to washing. The clean materials are dried and then usually pelletized in an extruder equipped with a melt filter to remove residual nonplastic contaminants. If mixed colors are processed, the result from typical curbside or drop-off programs is a grayish-green color, which is most often combined with a black color concentrate to produce black products. 

Recycled HDPE is also used in manufacture of flkn, especially for merchandise bags. Often, the material used is recycled milk bottles. Other uses of recycled HDPE are manufacture of miUc crates, curbside recycling bins, and other products. TransPac uses recycled HDPE in pallets, slip sheets, and pallet separator boards. DuPont uses recycled HDPE in its Tyvek envelopes. ... 

Prior to the start of the 24 week Ontario RPC program, no curbside collection of any plastic had occurred. A separate curbside program collected PET beverage bottles (along with other recyclables) prior to the addition of RPCs for the study. Following RPC introduction, the plastics composition by weight was as follows 65% HDPE/PP, 26%... 

The Madison, Wisconsin pilot, which collected recyclables commingled in clear plastic bags, recorded the collection times shown in Table 4.4. The average collection time for all four collection trucks utilized is about 1 minute per stop. This does not include dumping time, break time, and other time spent not related to collection, but does include time driving to and from the collection routes. No separation of materials was performed at curbside. 

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