The increasing awareness of the environment has raised so much concerns in the way we live and the manner to which we dispose our waste. The rapid growth in polymer production has resulted in increasing concerns about the consumption of nonrenewable resources and the environmental impacts associated with its production and disposal. Polymer waste is one of the major components in municipal solid waste and is increasingly becoming a huge burden in industrialized nations. The rise in the use of plastic, coupled with increasing concerns about its disposal, has led to a renewed interest in its recycling and recovery. The technologies involved in the recovery and recycling of polymers are rapidly growing, however, there is no specific pattern of treating polymer waste. The technology depends on the type of material used in the production and consumption pattern. This chapter, therefore, discusses the patterns of polymer consumption, the environmental concerns, and different modes of recycling polymer waste.
Top1. Introduction
Plastics are lightweight durable and inexpensive materials, which can be converted into a wide array of products that can be used in a wide range of applications. The production of plastics has dramatically increased in the last 60 years due to their wide applications and ease of molding (Jefferson et al., 2009). The amount of polymers used in the industry far exceeds that of metals and is rapidly growing due the industrialization of some developing nations (2003). Polymers are inevitable products in our lives today; they are widely used in place of alternate materials because they are inexpensive and they possess better environmental disposal options due to their light weight, minimal pressure on agricultural resources, and superior insulation abilities. Despite all the advantages, the current level of their usage and disposal pose serious danger to the environment and the health of the populace. In addition, around 4 percent of annual oil and gas production (non-renewable resource) is used as the parent material (precursor for synthesis) and the sole provider of energy for plastic production (British Plastics Federation 2008). Secondly, most of the plastic produced is directed for the production of disposable items that always end up in the landfills and in delicate habitats within short period of time. The impacts of polymer production have been sum up and depicted in Figure 1.
Figure 1. The impacts of polymer production
There are so many approaches in use to reduce the impacts of polymer disposal which include: source reduction, composting, degradation, incineration, recycling and landfilling (Richard 1992). Source reduction aim at reducing the volume or toxicity of waste generated and it is the most preferred management option, composting utilized biochemical means with the aid of microorganisms to reduce the volume of plastic waste generated, degradation uses factors such as heat, chemical or light to alter the properties of the polymers and lower its molecular weight for efficient recycling. Incineration which converts combustible waste to inert residue is a viable option because energy is generated but combustion of plastics generates significant amount of pollution. Incineration requires well-designed systems, adequate control and efficient maintenance. Disposal of plastics by landfilling is not a problem so long as space is available, however, most plastics are not biodegradable.
Recycling represents one of the most effective areas in polymer industry; it has significant advantages compared to other means of reducing polymer impacts because it reduces the consumption oil and gas, lowers emissions associated with polymer production, reduces the amount of waste generated and has ecological advantages, but its application is dependent upon the feasibility of elements of waste management i.e. handling, storage, processing, collection, sorting, and transport. Recycling of plastic materials has received rapid growth in the past few decades however, the quantities been recycled vary with locations according plastic type and application. Developments in the field of recycling are generating wide array of opportunities to people, legislators and government agencies and with proper investments, most plastic wastes been disposed to the landfills will be siphoned and directed for efficient recycling.
The recovery and recycling rate of plastics compared to other materials such as glass, paper, and metals is generally very slow. Plastic recycling even in developed nations with well-developed waste management systems in place is generally slow as compared to other materials because of the huge varieties of plastics, composites and additives used in their production. This complex nature of plastics confer added advantages when compared to other materials but it is generally problematic to recycling.
Top2. Polymer Consumption
The major producers of plastics in the world are China (23.9%), Europe (20.4%), North America (20%) and the rest of Asia excluding China (15.8%) (PlasticsEurope 2013) In the Europe, (39.4%) of the whole plastic production is directed for packaging materials, followed by construction (20.3%), automotive accounts for 8.2%, electrical and electronics accounts for 5.5% the plastic demand, agricultural applications account for 4.2% while other applications such as: medical, furniture, household and consumer products and appliances accounts for 22.4% . The world plastic production from 1950-2012 is shown in Figure 2.