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Life-Cycle Assessment of Acid Mine Drainage Treatment Processes

Kevin Harding

CONTENTS

  • 8.1 Introduction................................................................................................167
  • 8.2 Performing a Life-Cycle Assessment......................................................169
  • 8.2.1 Framework......................................................................................169
  • 8.2.2 Goal and Scope...............................................................................169
  • 8.2.3 Life-Cycle Inventory Analysis.....................................................170
  • 8.2.4 Life-Cycle Impact Assessment.....................................................172
  • 8.2.4.1 Classification....................................................................172
  • 8.2.4.2 Characterisation/Normalisation..................................172
  • 8.2.4.3 Valuation..........................................................................173
  • 8.2.5 Interpretation..................................................................................174
  • 8.3 Typical Studies of Life-Cycle Assessments............................................174
  • 8.4 Concluding Remarks.................................................................................179

References.............................................................................................................179

Introduction

There is a general trend to promote products, processes, and services by claiming that these are environmentally friendly. To support these claims, several techniques and labelling mechanisms exist. These include life-cycle assessment (LCA), carbon footprinting and water footprinting (the impact on global warming and water, respectively) as well as various eco-labelling schemes, including Energy Star, the Forestry Stewardship Council (FSC) (Bratt et al., 2011) and many others. While many of the techniques have genuine claims at being 'better' for the environment, one of the most robust and popular quantitative tools for environmental comparison is LCA. This section gives details on the basic concepts of LCA.

The LCA is a method used to assess the full environmental impacts of a system. It is a quantitative tool for evaluating the full effects that a system

FIGURE 8.1

'Cradle-to-grate' representation of an LCA, including reuse/recycling. When considering the final disposal of the product, this would be a 'cradle-to-grave' flowsheet.

has on the environment, including extraction, processing, manufacturing, transportation, distribution, use, reuse, maintenance, recycling, and final disposal. As a result, the LCA typically includes the 'cradle-to-grave' impacts of the system in question, but it may also include 'cradle-to-gate' (Figure 8.1) or 'gate-to-gate' impacts.

One of the advantages of LCA is that it can focus on a product, process, or service. While LCA is known to look at the entire system, it also has the advantage of being able to look at individual parts within the system, e.g., transportation, packaging, or manufacturing. In addition, it can consider broader geographic aspects (such as continent, country, or smaller geographic aspect, depending on available data) while avoiding social or political arguments. Since LCA is quantitative, the results should be reproducible, thereby enhancing its credibility.

The LCA by its nature is data intensive. Obtaining the required data may be difficult due to the quantity of data needed, the difficulty in measurement of the data, and the sensitivity of certain data (particularly if the data is not from one's own company). As a result of high volumes of data required, LCA practitioners often manipulate data using specialised software packages. This allows easier and faster calculations and standardisation (which also allows for data transfer across databases). To standardise studies, practitioners perform LCAs according to the framework defined by ISO (ISO 14040:2006; ISO 14044:2006), thus allowing for mutual understanding amongst practitioners.

 
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