Domestic waste plastics, recycling

The recycling of plastics waste is eonsidered with respect to energy recovery through incineration. It is claimed that burning solid municipal waste could produce nearly 10% of Europe s domestic electricity and heat and conserve resources by replacing, for example, over half of current coal imports to Western Europe. The potential for power from waste plastics and examples of energy from waste in action are described. 

Six samples of waste plastics were prepared for the tests. Four of them were obtained from a size reduction facility for industrial plastics recycling. The size of the plastics particles was about 2 to 10mm. The other two were obtained by being separated from domestic wastes collected in two cities and crushed to produce the size of 2 to 5 mm particles. These plastics particles were added to an asphalt mixture in quantities from 5 to 10 percent of the aggregate volume. 

Incineration of engineering and domestic wastes of inhibited plastics is inefficient in terms of energy production and leads to contamination of the atmosphere by harmful combustion products. In addition, incineration requires thorough sorting of waste, which is uneconomic. According to statistical information [25], incineration of a ton of polymer scrap is twice as expensive as recycling and five times expensive as burial. To obtain official permission to build an incineration plant is in fact improbable in many countries in the world today. 

M. Heyde and M. Kremer, Recycling and Recovery of Plastics from Packagings in Domestic Waste, LCA Documents Vol. 5, 1999. 

Recycling and Recovery of Plastics from Packaging in Domestic Waste—LCA-type Analysis of Different Strategies, Summary Report, Decanber 1998, obtainable from VKE, Frankfurt, or DSD, Cologne. 

Moreover, PP/LDPE blends are the products of plastic recycling. Since separation of PP and PE in sohd domestic waste (SDW) is very expensive, many recycling companies sell mixtures of reworked PE and PP ( polymer mix ) [13]. Thus, the study of the stmcture of blends of these materials will increase the field of application of recycled plastics. This is the reason for why PP-LDPE blends are the main subject considered in this chapter. 

Currently, only PET, high-density polyethylene (HOPE) and PP are being properly separated in municipal recycling streams in meaningful volumes across the developed world. However, it is predicted that innovations in continuous plastics detection and separation will eventually lead to materials such as PLA being easily redirected and reprocessed from domestic waste streams in the near future. 

Additives can add problems to recycling of plastics, but they can also be one of the means of identification, which might simplify the process. While analytical methods such as NIR and XRF are useful in recycling of domestic waste, LIBS finds application in case of thermoplasts (ABS, PP, PPO)... 

In Australia, a total of 167, 673 tonnes of plastics were recovered for recycling. Of this, 74 percent was processed domestically, and the remainder was exported, mostly to Asia. Plastics recycling has increased significantly in the last decade, with the 2000 amount 180 percent higher than that of 1992 and 80 percent higher than in 1997. While some of this may be due to better accounting, much of it is due to increased recycling. This amount includes both pre-consumer and post-consumer industrial and domestic waste materials. 

Deutschland System (DSD) [13] that to compete with conventional materials such as wood and concrete, plastics recycled from domestic waste would have to last 3.3 times as long as the materials they replace. From the known properties of recycled mixed plastics it is most unlikely that this could be achieved [10]. 

Contaminated mixed plastics wastes from domestic sources present a difficult challenge to traditional recycling techniques. On the other hand, the hydrocarbon portion of mixed domestic wastes can be made oxo-biodegradable by the incorporation of transition metal ions that accelerate both perooxidation and biodegradation. Oxo-biodegradable plastics thus make a realistic contribution to the recovery of value from waste packaging as fertilisers and soil-improvers for agriculture and horticulture. 

Details are given of a visit by RECOUP to BP Chemical s feedstock recycling demonstration unit in Sunbury. The feedstock recycling technology has been developed by a consortium of companies, and will enable polyolefin rich plastic waste from domestic and commercial sources to be vapourised and then condensed to form a hydrocarbon wax. This can then be used to feed existing petrochemical crackers to produce polymers indistinguishable from virgin material, it is claimed. 

An example of effective recycling of plastics waste from industrial and domestic sources is the... 

Brominated compounds will continue to hold much of the engineering plastics sector and thereby some dominance in the electrical and electronics (E E) sector. They will continue to be the most significant products because they are the most cost effective (and efficient) solution to many plastics flame retardancy applications. The EU Waste Electrical and Electronic Equipment (WEEE) directive and its effect on recycling plus the debate about fire safety versus environmental issues (especially in domestic appliances) will continue to attract much attention. 

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