Recycling of used plastics

Figure 121. Recycling of used plastics into new feedstocks (BASF)...

Recycling of Used Plastics. BASF is constructing a 15 000 t/a pilot plant for recycling of mixed, unwashed used plastics into feedstocks (Fig. 121). 

Synthesis gas, a mixture of mainly CO, CO2, and H2, has been used in chemical industry as feedstock and can be generated by gasification of coal and oil but also from biomass, municipal waste, or by recycling of used plastics (Kopke et al., 2010). Isobutanol production from synthesis gas has so far not been reported. However, Kopke et al. (2010) engineered Clostridium ljungdahlii, which is naturally able to use synthesis gas as carbon and energy source, for the production of 1-butanol by implementation of the CoA-dependent 1-butanol synthesis pathway from Clostridium acetobutylicum. The final titer of about 0.5 mM 1-butanol was rather low however, this approach demonstrated the feasibility to produce fuels and chemicals from synthesis gas. 

Recycle of Used Plastic Bottles with Supercritical Methanol... 

Supercritical fluids can be applied to remove polluting materials from the environment. Theory and practice of this technology is of increasing interest at the present time. In Supercritical fluids and reductions in environmental pollution by Koji Yamanaka and Hitoshi Ohtaki focus their attention to start with the thermodynamics and structure of supercritical fluids and then describe the supercritical water oxidation process, the extraction of pollutant from soils with supercritical carbon dioxide and other supercritical fluids, and recycle of used plastic bottles with supercritical methanol. Andrew I. Cooper et al. report on Supercritical carbon dioxide as a green solvent for... 

About 50 million tons of polyesters and 7 million tons of polyamides are produced worldwide annually. Although recycling of used plastic has become mandatory for environmental reasons, practically, it is still a challenge. Successful reuse of plastics depends heavily on a well-organized waste management system. Of all plastics, the waste logistics of polyesters is the best organized. About 50% of all PET bottles are collected for reuse in the EU. ... 

Stage 4 will involve the recycling of used plastic fuel tanks on an industrial scale. 

In recycling of used plastic products (recyclates), technical processes such as separation, purification, introduction of reinforcements, and additives, are usually included, depending on the source of the plastic, because thermoplastic products contain various different types of additives such as stabilizers, fillers, pigments, processing additives, and compatibilizers. The most common additives used for the recycling/reproduction of recyclates are phenolic antioxidants, phosphates, and costabiHzers such as anti-acids and light stabilizers. 

The results of studies are discussed into the co-combustion of plastics with respect to the recycling of scrap plastics from the building, packaging, automotive, electrical and electronic industries. Tests were carried out by APME on plastic waste from these end-use industries in a typical large scale EfW facility with respect to operational and environmental problems. 

The use of pyrolysis for the recycling of mixed plastics is discussed and it is shown that fluidised bed pyrolysis is particularly advantageous. It is demonstrated that 25 to 45% of product gas with a high heating value and 30 to 50% of an oil rich in aromatics can be recovered. The oil is found to be comparable with that of a mixture of light benzene and bituminous coal tar. Up to 60% of ethylene and propylene can be produced by using mixed polyolefins as feedstock. It is suggested that, under appropriate conditions, the pyrolysis process could be successful commercially. 23 refs. 

Methods for recycling used plastic materials are reviewed. Emphasis is placed on the research projects into chemical recycling methods for used plastics at the Leuna location. These include development of a process for the thermaL thermooxidative pretreatment of used plastic materials, utilisation of pretreated used plastic materials in the visbreaker by gasification and by hydrogenation and the production of wax oxidates from pretreated used plastics. The results are discussed. 

The EU Directive on Packaging and Packaging Waste sets a recovery target for used packaging of 25% by 2001 and 50-65% by 2005. It is likely that recycling of postconsumer plastics will require substantial polymer/additive analyses. 

Fitt, Italy s largest producer of PVC extruded and injection moulded products, recently presented a process for treating and using recycled post-use plastics from cables in the manufacture of pipe and moulded products. Tarkett Sommer, one of the world s largest PVC flooring manufacturers, processes almost 100,000 t/y of PVC at seven plants in Europe and is recycling about 8.4 tonnes of waste material a month. 

The chemical recycling of waste plastics consists of two processes the first is the degradation of waste plastics for the production of heavy oils, and the second is a catalytic cracking process that converts the heavy oils into useful hydrocarbons. To achieve these recycling goals, it remains necessary to develop efficient chemical recycling processes that can operate in a steam atmosphere. 

B. J. Milne, L. A. Behie and F. Berrnti, Recycling of waste plastics by ultrapyrolysis using an internally circulating fluidised bed reactor. Journal of Analytical and applied Pyrolysis, 51, 157-166, (1999). 

Feedstock recycling of waste plastic is an established method for recycling post-use plastics. Typically, waste plastics are recycled to naphtha, their raw material. This is... 

Production of nylons, pol5uirethanes, polyesters, polyolefins Cracking of used plastics to produce lighter molecules that can be recycled in new pol5uners... 

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