Page 53 - Materials Chemistry, Second Edition

34 Life Cycle Assessment of Wastewater Treatment

and 17% of EU territory. The EU policy paper on climate change published in 2009
highlights the need for further measures to enhance the efficiency of water use and to
increase resilience to climate change (European Commission, 2009). Concerns are
associated not only with the decreasing availability of freshwater but also with the
deterioration of water quality due to eutrophication or toxicity (Loubet et al., 2014).
Wastewater treatment plants (WWTPs) are the key stakeholders responsible
for effluent discharges into the aquatic environment. From the development of the
activated sludge process in 1914, the main focus in wastewater treatment has been
devoted to improving effluent quality, which has evolved in parallel with increas-
ingly strict discharge limits. In the European context, the conventional configuration
of WWTPs is designed to remove mainly organic matter and nitrogen. However,
the implementation of new discharge limits in accordance with the WFD requires a
search for environmentally efficient treatment schemes. In particular, the contribu-
tion of sewage treatment to climate change is considered as a major indirect environ-
mental impact. It has been estimated that around 1% of the average daily electricity
consumption in Western Europe is due to municipal and industrial wastewater treat-
ment. If hydrological management and agricultural demand are included, the con-
sumption could reach levels of 4%–5%, as reported in COST Action Water2020.
Therefore, the possibility of energy saving in WWTPs should acquire increasing
importance in the water treatment sector.
Beyond the target of reduced energy consumption, the idea of sustainable WWTPs
during conception, design, upgrading, and operation should be based on those technolo-
gies capable of maintaining a balance between desirable quality of emissions (effluent,
sludge, and gases) and recovered resources (reclaimed water, fertilizers, and energy)
in a multi-disciplinary approach. In this framework, WWTP performance needs to
be evaluated under technical, environmental, energetic, social, and economic aspects
adapted to the specific needs of each scenario (size, location, point of discharge, etc.).

3.2 LIFE CYCLE ASSESSMENT METHODOLOGY IN THE
FRAMEWORK OF WASTEWATER TREATMENT

Among the different environmental management tools, life cycle assessment (LCA)
is a method that allows the environmental impact of a product or a service to be
assessed in relation to its function over its whole life cycle, from raw material acqui-
sition to production, use, and disposal. The standard procedure for LCA developed
by the International Organization for Standardization (ISO, 1997) established the
stages of the methodology when addressing an LCA study: goal and scope definition,
the life cycle inventory (LCI) analysis phase, life cycle impact assessment (LCIA),
and the interpretation of results (Figure 3.1).

3.2.1 Goal and Scope
This is the first stage of the methodology and probably the most important, as
it includes essential elements of the study such as the purpose, scope, and main
hypotheses (ISO, 2006a,b).
To correctly set up the study, the functional unit (FU) has to be selected, that
is, the reference value to which all flows and emissions are referred. The adequate