Recycling environmental aspects

Environmental Aspects. More than two-thirds of aluminum cans are recaptured and returned for recycling into more cans. Because of the heat of melting, the use of post-consumer recycled cans is safe for beverage contents. Not only does recycling save on mass of materials, it also saves the energy of manufacture from aluminum ore (see Recycling, nonferrous metals). 

Environmental aspects, as well as the requirement of efficient mixing in the mixed acid process, have led to the development of single-phase nitrations. These can be divided into Hquid- and vapor-phase nitrations. One Hquid-phase technique involves the use of > 98% by weight nitric acid, with temperatures of 20—60°C and atmospheric pressure (21). The molar ratios of nitric acid benzene are 2 1 to 4 1. After the reaction is complete, excess nitric acid is vacuum distilled and recycled. An analogous process is used to simultaneously produce a nitrobenzene and dinitrotoluene mixture (22). A conversion of 100% is obtained without the formation of nitrophenols or nitrocresols. The nitrobenzene and dinitrotoluene are separated by distillation. 

Adhesives and resins are one of the most important raw materials in wood-based panels. Thus, each question concerning the life cycle assessment and the recycling of bonded wood panels does bring into question the adhesive resins used. This includes, for example, the impact of the resin on various environmental aspects such as waste water and effluents, emission of noxious volatile chemicals during production and from the finished boards, or the reuse for energy generation of wood panels. The type of resin has also a crucial influence on feasibility and efficiency for several material recycling processes. 

Key findings are reported from a study by David Brown of Warwick Research Institute into the environmental aspects of plastics packaging used for snack foods. The four options of reduction, re-use, recycling and recovery are discussed. The original research examines OPP as the most commonly used plastic for snack food packaging. BODY SHOP... 

Environmental aspects of PVC are examined on the basis of the findings of a number of studies carried out in Europe and the USA into recycling and waste disposal and the toxicity of phthalate plasticisers used in PVC toys and medical equipment. 

Recycling clearly has an important bearing upon fibre supply. There are two important environmental aspects to waste paper recycling. The first of these is what is known as the utilisation rate of waste paper and is defined as the waste paper consumption as a proportion of total paper and board production. The second useful definition is the recovery rate, which is simply the amount of waste paper recovered as a percentage of total paper and board consumption. An example of the use of such figures is shown in Table 10.1. 

The second part deals with applications of solvent extraction in industry, and begins with a general chapter (Chapter 7) that involves both equipment, flowsheet development, economic factors, and environmental aspects. Chapter 8 is concerned with fundamental engineering concepts for multistage extraction. Chapter 9 describes contactor design. It is followed by the industrial extraction of organic and biochemical compounds for purification and pharmaceutical uses (Chapter 10), recovery of metals for industrial production (Chapter 11), applications in the nuclear fuel cycle (Chapter 12), and recycling or waste treatment (Chapter 14). Analytical applications are briefly summarized in Chapter 13. The last chapters, Chapters 15 and 16, describe some newer developments in which the principle of solvent extraction has or may come into use, and theoretical developments. 

Finally, it should be emphasized that, while the concept of recycling proves to be of value, but in evaluation of the recycled products the environmental aspects and compatibility of the recycled systems with new applications must also be assessed. 

ENVIRONMENTAL ASPECTS OF RECYCLING VALVE-REGULATED LEAD-ACID BATTERIES... 

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