Potential Positive Environmental Impacts

Ftill LCA studies of biodegradable plastics in comparison to conventional petroleum-based plastics are required. However, environmental benefits that may be derived from the use of biodegradable plastics compared to conventional materials are outlined below. 

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Estimates over the Central and East European countries potential in oil production [3], presented in Figure 7, show good and effective CO2 utilization possibilities, taking into account that for Romania the figures indicate a considerable quantity of 91 Mt CO2 needed to further exploit the estimated oil resources. The main source for such a substantial quantity would be the flue gas from thermal power plants that are located near the oil fields, providing low transportation costs. The utilization of the CO2 emissions recovered from flue gas in such a considerable amount to fulfill the estimate potential for the injection into the local oil fields enhancing the bulk of oil recovery, would provide a significant positive environmental impact. 

The use of green yard waste compost on farmland can lead to a positive environmental impact with lower water usage, lower fertilizer usage, lower herbicide usage, and sequestration. Life cycle impact assessments of environmental concerns from production and application of composted products provide a net positive environmental impact. The use of composting process and products provides a reduction in GHG, human toxicity potential, ecotoxicity potential, and eutrophication potential due to lower use of fertilizers, herbicides, water, and electricity (LCA for Windrow Compost 2006). 

The recovery of e-caprolactam from waste PA-6 realises the high value of PA-6 and has therefore the potential to be economically competitive with the traditional synthesis processes significant positive environmental impact should also be mentioned. A presently applied recycling process is the Zimmer AG process, which performs the depolymerisation of PA-6 with the help of steam and liquid catalysts such as phosphoric acid [a.l7]. This process can be applied only for non-mixed PA-6 materials. A disadvantage of this process is the high yield of salts and traces of phosphoric acid in the recovered E-caprolactam, which is a drawback for the production of fibres. 

It is therefore important for stakeholders not only to focus on potential negative effects and the options to mitigate these but also to explore and incorporate the positive environmental impacts as a result of a project. This concept is promoted as Building with Nature (www.ecoshape.nl) or similarly Working with Nature (www.pianc.org/workingwithnature.php). 

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

In addition to band-gap and band-edge positions, some criteria for the selection of a good semiconductor include its chemical and photochemical stability and its environmental impact. Ti02 is the most popular semiconductor because of its resistivity to strong acids and bases and its stability under illumination [15,17,18]. ZnO, although its band-edge positions are very similar to those of Ti02 [30], is less desirable due to photocorrosion induced by self-oxidization. CdS has limited potential for practical use despite its attractive spectral response to solar radiation because CdS decomposes to release environmentally harmful Cd " [15]. 

In business, a life cycle approach can help identify environmental hot-spots within the product value chain, i.e., understand which parts of a product s life cycle have the greatest environmental impact as well as improvement potential. This in turn contributes to implement resource and energy efficiency, and to create an improved market position through more sustainable products. 

Owing to its comprehensiveness, LCA is a powerful tool for comparing different options/products with respect to their potential impacts on the environment, and for identifying the critical points within the product life-cycle that contribute most to these impacts [15]. This approach can be used, for example, for comparing a product that includes ENMs with similar products without ENMs. The added benefits of the use of ENMs may be reflected in the differences in the energy consumption for production of materials or products [29, 30], or in the use of scarce resources in the production processes. In other words, LCA may be used to assess the relative environmental performance of nanoproducts in comparison with their conventional equivalents. Thereby, LCA may also quantify the expected positive potentials of nanoproducts for the substitution of hazardous chemicals, the reduction in the use of materials, and energy consumption, in addition to waste reduction. 

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