Page 278 - Materials Chemistry, Second Edition

Support Sustainable Wastewater Treatment in Developing Countries 259

40 36
Number of publications 20 13 14 17 18 19 19 20 25 25
30

10
0
Marine aquatic ecotoxicity Terrestrial ecotoxicity Abiotic depletion Fresh water aquatic ecotoxicity Human toxicity Photochemical oxidation Ozone depletion Eutrophication Acidi cation Global warming

FIGURE 12.6 Impact categories most often adopted in the studies reviewed.

is strongly impacted by emissions of CO , CH , and N O from wastewater treatment
2
4
2
plants (Heimersson et al., 2016). Furthermore, N and P releases are important for eutro-
phication. Acidification, in turn, is impacted, for example, by hydrogen sulfide flow
from anaerobic processes, as well as by ammonia emissions from land application.
It was observed that 36 works, almost all studies analyzed, included global warm-
ing as an impact category. Indeed, some studies are dedicated to studying only this
impact category, such as Pan et al. (2011), which studied global warming–related
emissions from a wastewater treatment system in China. The interest of research
on global warming in developing countries is probably related to the fact that some
countries of this group are at the top of the list of the countries that present high
CO emission rates, such as Brazil, China, India, and Russia. Moreover, according
2
to the Intergovernmental Panel on Climate Change (IPCC, 2014), more than half of
the total amount of greenhouse gas emissions from waste comes from wastewater
management.
Acidification and eutrophication are in second position, as both presented 25
occurrences. Acidification is an important impact category in WWTPs in developing
countries because of the hydrogen sulfide emissions related to anaerobic treatment,
which is the preferred approach for treatment, as it does not demand energy related
to aeration and simplifies sludge treatment.
Furthermore, the high presence of the eutrophication impact category in several
studies is justified by the fact that it is considered a crucial impact category in LCA
applied to WWTP analysis (Corominas et al., 2013; Limphitakphong et al., 2016).
The importance of eutrophication in WWTP is explained by the fact that wastewater
treatment could prevent the release of nutrients to the environment, avoiding the
intensification of eutrophication processes (Wang et al., 2012).