Page 277 - Materials Chemistry, Second Edition

258 Life Cycle Assessment of Wastewater Treatment

an endpoint approach, this method is not suitable. From Figure 12.5, it is also noted
that in second and third position are ReCiPe and Eco-Indicator, respectively. The
former was developed based on CML and the Eco-Indicator model, allowing mid-
point and endpoint approaches to be integrated and harmonized, whereas the latter
follows an endpoint approach. Actually, Eco-Indicator was one of the early methods
to adopt endpoint thinking.
So, observing the three main methodologies adopted, it is noted that most
papers preferred to adopt traditional LCA methodologies. Indeed, 78% of papers
adopted one of the following LCA models: CML, Eco-Indicator, and ReCiPe. This
probably occurs due to the fact that LCA applications in most developing countries
are a recent area, which is still in development. So, the adoption of acknowledged
methodologies is justified, as it is likely to guarantee the robustness of the models
as well as to provide comparability of the studies. It seems that the choice of one
of these three methods was based on the intended approach: endpoint, midpoint,
or both.
It is important to note that other LCA methods, developed for specific regions of the
world, were also adopted, such as TRACI and LIME. For instance, Limphitakphong
et al. (2016) carried out a study in the context of Thailand adopting LIME, which is
an LCA method developed for Japan. Alarcon et al. (2011) and Garcia et al. (2011),
in turn, selected TRACI, an LCA model focused on the U.S. context, to investigate
wastewater systems. In general, the adoption of regional models is recommended, as
they can consider specific impact categories and provide regional characterization
factors, improving the accuracy of results. However, country-specific LCA models
for other countries, even those close to the home country of the LCA model, need
to be used with caution, as differences in some aspects, such as country energy mix
and normalization factors, could be strongly distinct. This is why the development of
regional LCA characterization factors on a regional level for Africa, Latin America,
and Asia is urgently recommended, as they will better represent the conditions of
these regions. Indeed, improvements provided by the regionalization of LCA models
will be very useful to support sustainable solutions in wastewater management in
developing countries.

12.4.9 iMpacT caTegories
The ten impact categories most often adopted in the studies analyzed are presented
in Figure 12.6.
It is noted that the most often used impact categories are the ones originating
from CML, which is expected, as it is the most widely used LCA model in the papers
analyzed.
The three most often used impact categories were global warming, acidification,
and eutrophication. This result is in agreement with the findings of Corominas et al.
(2013), who carried out a review involving LCA in wastewater without limiting the
papers to developing countries. For Heimerson et al. (2016), the interest in research on
these impact categories is probably linked to the emissions of N, P, and C from waste-
water treatment, which directly impact them. Indeed, the global warming category