Drink bottles, recycling

FIGURE 8.22 PET soft drink bottle recycling amounts in the United States. ... 

The existence of bottle deposit legislation continues to be an important factor in PET recycling. It was estimated that, in 1997, 54% of the PET soft drink bottles recycled came from bottle-bill states, while these states accounted for only 29% of the population. Recycling rates for soft drink bottles in deposit states range from 76 to 90%. It should be noted that the low end represents California, which has a bottle refund system rather than a true deposit. The monetary incentive in California is lower than in true deposit states, and the refund system is less convenient. 

In America there are promising signs for certain polymers. For example, poly(ethylene terephthalate) drinks bottles can be cleaned and recycled to give an acceptable grade of PET resin in a process that is economically viable. The recycled polymer is used as carpet fibre, furniture stuffing, or insulation. Waste nylon can also be recycled profitably. 

Total recycled thermoplastic resin production almost tripled between 1990 and 1995 and is well over 1 billion lb per year. The percentage breakdown of the amount for recycling is the following HDPE (especially bottles), 35% PET (soft drink bottles), 34% PP (auto battery cases), 14% LDPE (film), 9% PS (packaging), 3% PVC, 0.5% other, 4%. 

The recycling of plastics also contributes to energy efficiency. Soft drink bottles made from polyethylene terephthalate reached a recycling rate of 41% in the U.S. in 1995 (19). Recycling is becoming widespread, and many studies are in progress to develop new and improved recycling practices. 

PET from post-consumer soft-drink bottles was cut into small pieces and batches of this raw material ( 40 g) were pyrolysed in a first step at 400 °C, under nitrogen atmosphere, in a 35 mm internal diameter vertical quartz reactor. Then, a second heat treatment was performed, at 725 °C for 2 hours. The distribution of the final products of the pyrolysis process was approximately 58% of gaseous compounds (CO, CO2 and a complex mixture of hydrocarbons), 20% of a yellow crystal solid that condensed in the upper part of the reactor, and 22% of a black solid residue (i.e., char, denoted as P) with a glassy sheen, retrieved from the bottom of the reactor. The characterisation of the yellow crystal solid revealed that terephthalic acid was the principal component, which can be recycled for PET synthesis. 

Recycling of unwanted polymers is the best solution, and six types of plastics in common use are frequently stamped with identifying codes assigned by the Society of the Plastics Industry (Table 31.2). After sorting by type, the items to be recycled are shredded into small chips, washed, dried, and melted for reuse. Soft-drink bottles, for instance, are made from recycled poly(ethylene terephthalate), trash bags are made from recycled low-density polyethylene, and garden furniture is made from recycled polypropylene and mixed plastics. 

Plastic lumber is made from recycled plastic, especially soft drink bottles and polyethylene waste. 

Sustaining value chains is about finding ways to make the value chains in which Shell chemicals companies participate more sustainable. Examples include the development of cool wash detergents, and the PETFix technology to recycle waste PET drinks bottles into building materials. 

IB. Measure current levels of material recycling. Some materials may be transferred from one unit to another (e.g., reuse of the final rinse in a soft-drink bottle washing plant as the initial rinse) either directly or after some modificafions/treatment. If recycled materials are not properly documented, double counting may occur in the material balance, particularly at the process or complete plant level that is, a material will be quantified as an output from one process and as an input to another. Proper attention must be paid to this issue, and care must be taken to avoid any discrepancies. 

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