Sources of plastic waste

Scenario with a recyclable ecoplastic 10.7.1. Sources of plastic waste 

In contrast to this example, we can say that the use of recycled plastic waste is limited by the difficulty in transporting it as little as possible, sorting it for the lowest possible cost and regenerating the material with as few operations and additives as possible. Another limiting factor is that it is often difficult for a transformer to obtain recycled plastics of consistent and clearly known quahty. 

If we wish to circumvent these various problems, it is necessary to use clearly identified waste products, characterize their recyclability and find an apphcation compatible with their lesser performances once recycled. 

In this example, we have looked at the recyclability, by injection, of polycarbonate (PC) waste from cutting up temporary signposts based on extmded 

One advantage of these waste products is that they are clean, clearly identified and we can expect that, by beginiiing with a plastic such as PC, which is known for its good initial mechaiucal properties, it will be possible to preserve an acceptable standard of properties for common applications after recycling. 

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It is instructive to consider the sources of plastics waste. Table 11.1 shows the types of plastics and their use in packaging, whilst Table 11.2 shows the proportion of waste classified by end use. This shows how significant packaging is in generating waste, and causing environmental problems. Applications such as furniture and electrical appliances show more acceptable use of polymers, because discard rates are low and lifetimes of the products are generally long. 

There is no shortage of sources of plastic waste on this planet (see Figure 10.24), but at present the potential resource they offer is only very partially exploited. Their use is not really a financially viable option, because while virgin plastics are inexpensive to manufacture, waste plastics need to be treated and transported, have poorer properties than the virgin material and the applications of recycled plastics have only little added value. 

The most satisfactory strategy for successful recycling of engineering polymers to durable end products is to use only one source of plastic waste whose composition and history are known. This then permits the design of a stabiliser system which will S5mergise effectively with what remains of the previous stabiliser package or, at worst, will not antagonise with it. 

The second and the biggest source of plastic wastes generation, which creates the real problem, is termed post-consumer wastes . Three kinds of wastes are generated municipal, agricultural, and uncontrolled plastic wastes. The last group of plastic wastes must not be considered in the sense of a technical problem because they can only be avoided due to common consent of users of public... 

In a rotary kiln, the burner can produce both thermal and fuel NO, if the fuel contains nitrogen. Many soHd waste streams also contain nitrogen, typically as much as 20 wt %, which contributes to the fuel NO pathway. Key sources of soHd waste fuel nitrogen include plastics, nylons, dyes, and other process wastes. Nylon, for example, is 33 wt % nitrogen. 

Biodegradable films made from edible biopolymers from renewable sources could become an important factor in reducing the environmental impact of plastic waste. Proteins, lipids, and polysaccharides are the main biopolymers employed to make edible films and coatings. Which of these components are present in different proportions and determine the properties of the material, as a barrier to water vapor, oxygen, carbon dioxide, and lipid transfer in food systems (Gomez-Guillen et al. 2002 and 2009). 

The waste management situation in Austria is presented, and it is explained that Baufeld-Austria GmbH has developed a method and concept, with the eooperation of cement plant experts, to enable some Austrian eement factories to responsibly use plastics waste as an energy source. The conditions used for developing the model, relating to fuel quality, environmental proteetion, and public health, are explained. The Baufeld model for processing of plastics waste is then described. Details of future plans are included. 

The severe limitations on the mechanical recycling of plastic wastes highlight the interest and potential of feedstock recycling, also called chemical or tertiary recycling.17,18 It is based on the decomposition of polymers by means of heat, chemical agents and catalysts to yield a variety of products ranging from the starting monomers to mixtures of compounds, mainly hydrocarbons, with possible applications as a source of chemicals or fuels. The products derived from the plastic decomposition exhibit properties and quality similar to those of their counterparts prepared by conventional methods. 

Figure 1.15 Automated sorting facility of plastic wastes based on IR radiation27 IR source (1), IR detector (2), computer with spectrum library (3), main conveyor (4), compressed air (5), solenoid valves (6), pusher (7).

If we analyze plastic consumption per sector, as we can see from Figure 10.26, for Europe in 2009, packaging was the most significant source of potential waste, followed by constmction, the automobile industry and the electronics industry. 

Over 16 million tons of post-user plastics waste is produced in Western Europe every year and more than half is produced by households (Table 4.1). Although many items of packaging are re-used at least once (notably carrier bags and bottles), this does little to reduce the burden on the municipal waste collection systems. The source of packaging waste is not always clear in published statistics. Stretch-wrap film used for packaging hay is not classified as agricultural waste nor does it appear as industrial waste but it is a severe pollution problem for the farmer and a visual blight in the countryside. 

As well as direct incineration of plastics waste, imder clean and efficient conditions, there has been some research into conversion into fuel oil, by chemical methods. The Veba Combi-Cracking (VCC) process produces synthetic crude oil under liquid phase hydration. In trials, 100 tonnes of mixed and contaminated plastics waste from normal domestic sources was hydrated to high quality oil, similar to that used as a source for diesel fuel. With metal-free granular material, costs were estimated at about DM 500/tonne. The process has also been used with polyurethane waste, producing oil that can be mixed with new oil (but costing over twice). 

Over the past years, plastics have gathered a rather bad reputation as they are able to resist degradation and therefore accumulate in the environment [1]. The fact that most of these plastic materials are derived from fossil natural sources has contributed significantly to these environmental issues since plastics are generally labelled "unsustainable . Additionally, their low cost of production renders them easily disposable, resulting in high amounts of plastic waste being discarded annually. 

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

This standard establishes the different options for the recovery of plastics waste arising from pre-consumer and post-consumer sources. It also establishes the quality requirements that should be considered in all steps of the recovery process, and provides general recommendations for inclusion in material standards, test standards and product specifications. Consequently, the process stages, requirements, recommendations and terminology presented in the standard are intended to be of general applicability. 

The waste to energy recovery route covers energy via incineration or as a fuel source in smelters, cement kilns or chalk ovens as is often the ease with plastic waste today. Past problems with standards of operation at incinerators, such as operating temperature, residence times and emissions, led to concerns over the incineration of plastics waste in the past. However, sinee that time more stringent requirements for operation have been introduced, such as a minimum of 850 °C in the combustion chamber, minimum of 2 sec residence time for the resulting flue gases at 850 °C, in the presence of at least 6% oxygen. 

Different sources (including waste) are being investigated for extracting energy. For example, Ozmotech, a major Australian company, has developed a pyrolysis process under inert-atmosphere to convert 400,000 tons of plastic waste into 350 million liters of diesel per annum (Ecos, 2006). 

It is likely that in the near future, starch, oilseed, or leguminous plants will be used to produce PHAs. Other plant materials such as cellulose and starch are already used to make plastics or plastic-like materials. Hemicelluloses have been used directly and/or converted to organic acids for PHA production at a laboratory scale. Thus any waste from the separation of PHA from plants could be hydrolyzed, fermented to lactic, acetic, and propionic acids, and then fed into bioreactors for the production of specialty PHAs. Polylactides and other polymers of organic acids could be produced in the same plant as could polysaccharides. Plant materials may become a major source of plastic materials in the next century with PHAs leading the way. 

Due to industrialization of the process, the only sure feedstock source of large quantities of plastics wastes is from urban wastes, not only in large quantity but also with a certain consistency in composition. 

Compared with synthetic sources, renewable polymer composite sources have a lot of advantages, particularly as a solution to the environmental concerns of plastic waste. Renewable polymer composites can maintain sustainable development of ecologically attractive technology that is also economic (Okamoto 2004). Eco-friendly polymer composites (EPC) are widely studied, due to the need for innovations in the development of materials from biodegradable polymers and renewable raw materials. EPC has also attracted tremendous research interest, due... 

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