Life Cycle Assessment as a tool for green chemistry: Application to different advance oxidation processes for wastewater treatment, Munoz Ortiz Ivan
Abstract
The goal of the thesis is to contribute to the acceptance of Life Cycle Assessment (LCA) as a methodological tool for environmental evaluation of chemical processes designed by following the guidelines of Green Chemistry. This work also intends to complement and to integrate in the same framework the environmental assessment with the respective economic assessment, taking into account a life cycle perspective as well. In order to demonstrate the potential suitability of the LCA tool in this context, two case studies are carried out on the subject of Advanced Oxidation Processes (AOPs) for treating industrial wastewaters containing persistent organic pollutants. In particular, the evaluated AOP technologies are: heterogeneous photocatalysis, homogeneous photo-Fenton, and ozonation. The first case study is carried out by exclusively using data derived from laboratory experiments, while the second case study is more detailed, and carried out by using data from pilot plants and industrial plants. Both studies include, along with the environmental assessment, the corresponding economic assessment, based on Life Cycle Costing (LCC). Following these studies, a discussion is made on the suitability of LCA in the context of chemical processes depending on the scale of analysis. Finally, the overall conclusions of the thesis are outlined, which can be summarised as follows:
- In order to assess the advances derived from applying Green Chemistry principles in the design of chemicals and chemical processes, methodological tools are needed. This thesis supports that LCA can be used for such a purpose, as has been shown by means of two case studies on AOPs.
- Application of LCA can be carried out at several stages: from the most basic, namely the laboratory scale, to the most advanced, namely commercial application. However, results obtained by means LCA studies based exclusively on laboratory-derived data do not necessarily match the results obtained in a detailed LCAs, mainly due to: 1) lack of optimization of the conditions in which the chemical process takes place in laboratory tests, and 2) excluding relevant operations or life cycle phases which are hardly quantifiable when evaluated from laboratory tests. For this reason, it is suggested that laboratory-derived LCAs should be used only as a means of obtaining preliminary environmental information.
- The potential of LCA as a tool is displayed when detailed studies, based on large-scale application data, are carried out. The LCC tool, on the other hand, presents itself as a very suitable complement, mainly when performing detailed studies.
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