Life cycle assessment (LCA) has been proved to act as a desirable tool to evaluate the environmental impacts of wastewater treatment plants (WWTPs). However, the application of LCA methodology in the field of wastewater treatment is still in progress. This ppt has made a review of the LCA studies dealing with biological (activated sludge) WWTPs, with the aim to provide qualitative interpretation of the associated environmental impact categories: eutrophication potential, global warming potential, toxicity-related impacts, energy balance, water use, land use and other impact categories.

1. Presented By Abdul Sami
Research Paper assigned by Dr. Sheeraz
Institute of Energy, Environmental
Engineering & Management
Mehran
University
of Engineering
& Technology
Jamshoro

2. Black water has come
into contact with fecal
matter. Fecal matter is a
haven for
harmful bacteria and
disease-
causing pathogens.
Gray water, on the
other hand, has not
come into contact with
solid human waste
Storm water, That
comes from Storms
and Rain

3. Life Cycle Assessment
• assessing the impacts on
human health and the
environment associated with
energy and raw material and
environmental releases.
• evaluating opportunities to
reduce energy, material
inputs, or environmental
impacts at each stage of the
product life-cycle.
• quantifying the energy and
raw material inputs and
environmental releases
associated with each stage of
production
• purpose and the expected
products of the study, and
determining the boundaries
(what is and is not included in
the study)
Goal
definition and
scoping
Life-cycle
inventory
Impact
analysis
Improvement
analysis

4. Conventional wastewater treatment Plant

5. A b s t r a c t Total words 271
Life cycle assessment (LCA) has been proved to act as a desirable tool to evaluate the environmental
impacts of wastewater treatment plants (WWTPs). However, the application of LCA methodology in the
field of wastewater treatment is still in progress. This paper has made a review of the LCA studies dealing
with biological (activated sludge) WWTPs, with the aim to provide qualitative interpretation of the
associated environmental impact categories: eutrophication potential, global warming potential,
toxicity-related impacts, energy balance, water use, land use and other impact categories. Possible
sources for each impact category of WWTPs are summarized in order to provide information about the
critical aspects in WWTP systems that might influence LCA results. Moreover, recent development and
the application status of characterization models for each impact category have been reviewed. The
analysis indicates that it is important to carry out site-specific LCA studies on WWTPs. The specificity is
most typical for the eutrophication potential and toxicity-related impact categories, which need
implementation of spatial differentiated characterization methods, considering the emission location,
spatial dimensions (transfer between environmental compartments) and even properties of pollutants.
Although remarkable progresses have been obtained, their applications in the field of wastewater
treatment are still limited. For the global warming potential impact category, it is most crucial to
calculate accurately the greenhouse gas (GHG) emissions, because nitrous oxide (N2O) and methane
(CH4), as well as fossil origin carbon dioxide (CO2) in wastewater have the potential to make considerable
contributions. In the end, prospective is made about which aspects in WWTPs are candidates for further
LCA studies. Overall, there is still room for pursuing more accurate results when applying LCA to WWTPs.
© 2015 Elsevier Ltd. All rights reserved.

6. A b s t r a c t (Improved) Total words 198
A review of the LCA studies dealing with biological (activated sludge) WWTPs has been made, to provide
qualitative interpretation of the associated environmental impact categories: eutrophication potential, global
warming potential, toxicity-related impacts, energy balance, water use and land use. Possible sources for each
impact category of WWTPs are summarized in order to provide information about the critical aspects in WWTP
systems that might influence LCA results. Moreover, recent development and the application status of
characterization models for each impact category have been reviewed. Due to specificity of the eutrophication
potential and toxicity-related impact categories, need implementation and site-specific LCA studies are
suggested, considering the emission location and properties of pollutants. While obtaining the remarkable
progress, still applications in the field of WWT are limited. For the global warming potential impact category, it is
most crucial to calculate accurately the greenhouse gas (GHG) emissions, because nitrous oxide (N2O) and
methane (CH4), as well as fossil origin carbon dioxide (CO2) in wastewater have the potential to make
considerable contributions. In the end, prospective is made about which aspects in WWTPs are candidates for
further LCA studies. Overall, there is still room for pursuing more accurate results when applying LCA to WWTPs.

7. • The environmental issue is now recognized as one of the major
concerns in many proposed projects (Dennison et al., 1998).
• Wastewater treatment plants (WWTPs) have been designed and
operated to reduce the pollution of wastewater produced by human
activities in order to minimize the negative influences on
environmental quality and human health (Wang et al., 2012).
• WWTPs bring many other adverse environmental impacts at the same
time due to material and energy consumption, various emissions to
environment, as well as the generated sludge which requires
additional treatment (Hospido et al., 2004).

8. • Thus, to achieve the objective of true sustainability, the
environmental impacts of WWTPs should not exceed the benefits of
remediation.
• Need of assessment from an integrated perspective.
• Several reviews on LCA studies dealing with WWTPs have been
published.
• Recently, following LCA methodological steps (Corominas et al.
(2013b) have taken a comprehensive analysis of LCA studies on
wastewater treatment, trying to identify what had been achieved and
depict the challenges for the future.

11. • Nevertheless, it is noted that no review is specifically conducted to
investigate the Results of WWTP-related LCA studies, on a
comprehensive scale.
• Therefore, this paper tries to fill this gap by summarizing a large
portion of the existing scientific literatures that explicitly use LCA
methodology, or a life-cycle approach, to assess the environmental
impacts of WWTPs.

13. Method
upstream processes
Comprise wastewater collection
and transport to the plant.
Core processes
include the plant construction,
operation (energy consumption
for treatment steps,
manufacture of chemicals and
maintenance material, resources
consumption and the handling of
process-related emissions and
waste, etc.)
Downstream processes
Represent the production of by-
products (e.g. electricity/heat by
biogas, residuals to recycling).
Product
Category
Rules
(PCR)
• It is noted that lots of WWTP-related LCA studies (Table 1) have expanded their system boundaries to include downstream
processes, i.e. material substitution (replacement of potable water by wastewater reuse; fertilizer production avoided by
agricultural application of sludge) or energy recovery (energy production avoided by biogas from anaerobic digestion or
incineration of sludge). we specifically focus on LCA studies best corresponding to wastewater treatment, with the main
attention being paid to biological (activated sludge) wastewater treatment technologies.

14. Input and Outputs of a Core Stream Process
wastewater
Energy
chemicals
Various emissions to the
surrounding environment, i.e.
water (mainly due to wastewater
effluent), air (CO2, CH4 and so on)
and soil (mainly due to agricultural
application or landfill of sludge,
irrigation of treated wastewater
and so on)

15. • Several researchers have focused on comparing conventional wastewater
treatment technologies with source-separation wastewater treatment
systems, which treat separately domestic sewage depending on different
sources (i.e. black and gray water)
• The benefits are related to limiting nutrient emissions to aquatic
environment (because nutrients have been separated from wastewater)
and preventing toxic substances to agricultural land (since fertilizer use has
been avoided).
• However, other environmental impacts, e.g. ammonia emissions from
digestate (i.e. anaerobic digestion of black water), emissions from multiple
infrastructure for source separating systems might impose challenges on
the application of source separation systems

17. Eutrophication
• The process by
which a body of
water becomes
enriched in
dissolved nutrients
(as phosphorus &
nitrogen) that
stimulate the
growth of aquatic
plant life usually
resulting in the
depletion of
dissolved oxygen

18. Eutrophication Potential
• Nutrients in the effluent has been considered the most relevant
environmental issue when performing environmental evaluation of
WWTPs.
• impact can be decreased immediately by implementing more
sophisticated technology to enhance the nutrient removal efficiency
• it is realized by an increasing number of researchers that today's WWTPs
LCA, which focuses on what must be removed from wastewater, should be
shifted to a new one focusing on what can be recovered
• It is reported that freshwater eutrophication is more cause by (P) emissions
in effluents whereas the Marine eutrophication is more caused by Nitrogen

19. Global warming potential
• Gradual increase in the overall temperature of the earth's
atmosphere generally attributed to the greenhouse effect caused by
increased levels of CO₂, N₂O, and other pollutants.
Direct Emissions
N2O generated from secondary
biological wastewater treatment
(denitrification)
CH4 from the anaerobic wastewater
and/or sludge treatment process.
CO2 emissions from (aerobic
biodegradation) treatment process
Indirect Emissions
GHG emissions mainly stem from
the production of electricity and
chemicals used in WWTPs,
transportation of fuel, chemicals
and wastes, degradation of
remaining constituents in the
effluent and sludge receiving
environment

20. Global warming potential
• recently found that emissions of N2O (mainly from water line) are the
most significant contributors, about 3 times more important than
electricity use.
• The dominant role of N2O in direct GHG emissions is also discovered.
• Although results from different LCA studies vary with different
assumptions, these conclusions remind us that more consideration
should be paid to N2O emissions in WWTPs.
• However, large uncertainties are associated with the emission
estimation is due to the difficulty of identifying the prominent
mechanism of wastewater nitrification-denitrification process (Foley
et al., 2010b). Numerous efforts have been made to quantify the N2O
emissions more accurately.

21. Toxicity-related impact categories
• Large discrepancies in toxic impact categories are observed.
• It has been pointed out that the differences between LCIA methods
regarding the toxicity impacts mainly lie in the phase of
characterization;
• inclusion/exclusion of specific substances.
• when comparing different LCIA methods, great distinction is found
regarding the toxic ranking of pollutants.
• Therefore, further LCA studies need to investigate whether or not the
potential impacts on ecosystems and human health are actually
reduced.

22. Conclusion
• This paper has analyzed LCA studies dealing with WWTPs, which are based on
biological (activated sludge) technologies. LCA is generally used by researchers for
comparing and optimizing the WWTP systems, as well as the resource and energy
recovery alternatives.
• Efforts have also been made to investigate further development of some specific
impact categories in the field of wastewater treatment.
• Although many variables are involved in LCA results, this paper has provided
qualitative interpretation for the associated environmental impact categories.
• The possible sources for each impact category of WWTPs are summarized in
order to provide information about the critical aspects in WWTP systems that
might influence the LCA results.
• Moreover, recent development and the application status of characterization
models for each impact category has been reviewed.
• We can deduce that the most important issue is to carry out site-specific LCA
studies on WWTPs.

23. Thank you