Sustainability environmental

The previous sections of this chapter have examined the manufacturing of PLA, its various properties as a polymer and a fiber, and considered the potential for its use in a range of commercial applications. Additionally, the environmental aspects for producing and using PLA products must be appraised in any discussion about its significance as a sustainable commercial polymer material. 

Environmental sustainability is about making products that serve useful market and social functions with lower detrimental environmental impact than the currently available alternatives. The case for PLA in this respect 

According to Vink et al there are probably three items that are generally considered to have an increasing global importance with regard to environmental concerns fossil energy use greenhouse gas emissions and water use. 

It needs to be recognized that the data for PEAl and PEA B/WP represent engineering estimates. In addition, there is good reason to expect improvements in the actual performance versus the estimates. Despite years of development work, the commercial manufacturing process for PEA is in its infancy. If the experience from petrochemical-based polymers offers any instruction, it is that process improvements implemented in the early years of a technology typically lead to substantial cost improvements. This is because the pursuit 

Global climate change has been identified as perhaps the most important environmental issue of this century. Greenhouse gas emissions are not exactly the same as combusted fossil fuel emissions, because several noncombustion gases can contribute to global climate change as well. For example, 

Waste generation is a growing problem around the world. There is a range of international legislation in place to try and deal with it, as well as volimtary targets aimed at all sectors of society. 

In general, there are different types of wastes [ 1 ]. These include  

Solid waste collection, transfer and disposal have become a major concern worldwide [ 1,3]. In many countries, conventional systems are able to collect between 30-50% of solid wastes, and these wastes are disposed in ways detrimental to the environment. Accordingly, wastes can be diverted from disposal through a variety of means, including reuse, recycling and composting, to environmentally friendly and sustainable practices. 

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To develop new fuels and materials and to provide environmentally sustainable solutions to energy generation problems... 

All fossil fuels are considered unsustainable because someday they will reach a point of depletion when it becomes uneconomic to produce. Petroleum is the least sustainable because it is the most finite fossil fuel. Although levels of production are expected to begin declining no later than 2030 (U.S. production peaked in 1970), the U.S. and world resei ves could be further expanded by technological advances that continue to improve discoveiy rates and individual well productivity. The extraction of oils found in shales (exceeds three trillion barrels of oil equivalent worldwide) and sands (resei ves of at least two trillion barrels worldwide) could also significantly increase reserves. The reserves of natural gas are comparable to that of oil, but natural gas is considered a more sustainable resource since consumption rates are lower and it burns cleaner than petroleum products (more environmentally sustainable). 

ICI Acrylics believes that greater cooperation between companies and a revised approach to life cycle analysis are the keys to the industry s future environmental sustainability. The company has invested over 2m pounds sterling in an on-going monomer recovery project, which encompasses a joint research programme with Mitsubishi Rayon. The project focuses on increasing the efficiency of acrylic depolymerisation and overcoming technical issues such as its use in recycling flame retardant acrylics. ICI ACRYLICS... 

City of Toronto, 2000. Clean, Green and Healthy A Plan for an Environmentally Sustainable Toronto, Environmental Task Force, Proposed Environmental Plan, January 2000. 

Metz N. Contribution of passenger cars and trucks. 2001 Environmental Sustainability Conference and Exhibition, Austria Graz. 

Based on the previous studies and the above discussions, it is required to achieve environmentally sustainable development in textile industry since closing of water cycle is highly recommended [29]. It can often be done by the application of the combined membrane-biological processes, especially by the implementation of NF-biological and RO-biological processes, which enables the water reuse process, thereby the minimization of freshwater consumption. 

Sands GR, Podmore TH (2000) A generalized environmental sustainability index for agricultural systems. Agric Ecosys Environ 79 29—41... 

Closing a water loop is primarily focused on the achievement of a more environmentally sustainable production process. The treatment scenarios that have been identified as technically feasible should be further evaluated on criteria of environmental sustainability. Within the context of closing industrial water loops the following environmental effects have to be considered at a minimum ... 

A broader and more detailed evaluation can be done by performing a Life Cycle Analysis (LCA). The central idea of a LCA is that the environmental effects during the entire life cycle of a process are quantified. These environmental effects are caused by the use of fossil fuels for heating and production of electricity, the use of non-renewable raw materials for the production of materials and chemicals, and the emissions of pollutants to air, water and soil. These environmental effects can be subdivided further in various levels of detail. The five major effects mentioned are derived from the more general effects considered in the framework of the LCA. Based on the environmental sustainability of each of the complete treatment scenarios considered as technically feasible, a ranking according environmental... 

In general it is not possible to develop a complete treatment scenario that is optimal technically, financially and also with respect to environmental sustainability. A solution has to be found which is economically and technically feasible and also satisfies the criteria of environmental sustainability to the greatest possible extent. An additional criterion for the selection of a complete closed loop water system can be obtained if the net environmental benefits are compared with the extra costs of the closed loop system. In this way the extra environmental benefits per unit investment costs or operating costs can be calculated. In the final selection of a closed loop water system aspects dealing with acceptability and public environmental awareness also play an important role. 

The starting point in the development and designing of a closed water loop system is an inventory of the amounts and the quality of the process and transport water flows which are needed for the various steps in the production process. Each production step where process or transport water is involved causes a certain amount of wastewater. The pollution of this water is strongly dependent on the process step. The selection of separate treatment steps which, together, comprise a closed loop water system is complex. As already mentioned, various complete treatment scenarios can be developed and designed to satisfy the requirements set for process and transport water and treatment of wastewater. A technical and economic evaluation, in combination with environmental sustainability assessment, is necessary to determine the treatment system which is most appropriate. 

Closing the water loop is, in general, a first important step to achieve more sustainable production processes. A further improvement of the environmental sustainability of the production process can be obtained by an environmental assessment of all material and energy flows in the production process. This gives a more complete picture of possible ways to save on materials and energy use, and also how to minimise the amount of final wastes from the production process. 

A further improvement in the sustainability of an industrial production process may be achieved by closing the water loops for a number of adjacent industrial production processes. This may be achieved in a so-called eco-industrial area where the primary aim is to arrange industrial production processes in such a way that water, wastes, materials, and energy can be exchanged between the various production processes in an environmentally sustainable and cost effective manner. A shared process water production plant and wastewater treatment plant is then a crucial step. It will, however, be clear that such an approach requires a thorough and detailed study which incorporates not only technical and economical aspects but also legal, organisational and infrastructural aspects as well. 

Organisation for Economic Co-operation and Development (OECD) (2002). Policy Instruments for Achieving Environmentally Sustainable Transport. Paris OECD. 

We present a short discussion of the economic and societal backgrounds for the search of alternatives to fossil fuels or technologies that make their use environmentally sustainable. 

N-management practices to attain environmental sustainability are expected to have both low nitrate leaching potential and low nitrate leaching rate. 

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